In gcc/:

[pf3gnuchains/gcc-fork.git] / gcc / objc / objc-act.c

/* Implement classes and message passing for Objective C.
   Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001,
   2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010
   Free Software Foundation, Inc.
   Contributed by Steve Naroff.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"

#ifdef OBJCPLUS
#include "cp-tree.h"
#else
#include "c-tree.h"
#include "c-lang.h"
#endif

#include "c-family/c-common.h"
#include "c-family/c-pragma.h"
#include "c-family/c-format.h"
#include "flags.h"
#include "langhooks.h"
#include "objc-act.h"
#include "input.h"
#include "function.h"
#include "output.h"
#include "toplev.h"
#include "ggc.h"
#include "debug.h"
#include "target.h"
#include "diagnostic-core.h"
#include "intl.h"
#include "cgraph.h"
#include "tree-iterator.h"
#include "hashtab.h"
#include "langhooks-def.h"

/* For default_tree_printer ().  */
#include "tree-pretty-print.h"

/* For enum gimplify_status */
#include "gimple.h"

#define OBJC_VOID_AT_END        void_list_node

static unsigned int should_call_super_dealloc = 0;

/* When building Objective-C++, we need in_late_binary_op.  */
#ifdef OBJCPLUS
bool in_late_binary_op = false;
#endif  /* OBJCPLUS */

/* When building Objective-C++, we are not linking against the C front-end
   and so need to replicate the C tree-construction functions in some way.  */
#ifdef OBJCPLUS
#define OBJCP_REMAP_FUNCTIONS
#include "objcp-decl.h"
#endif  /* OBJCPLUS */

/* This is the default way of generating a method name.  */
/* This has the problem that "test_method:argument:" and
   "test:method_argument:" will generate the same name
   ("_i_Test__test_method_argument_" for an instance method of the
   class "Test"), so you can't have them both in the same class!
   Moreover, the demangling (going from
   "_i_Test__test_method_argument" back to the original name) is
   undefined because there are two correct ways of demangling the
   name.  */
#ifndef OBJC_GEN_METHOD_LABEL
#define OBJC_GEN_METHOD_LABEL(BUF, IS_INST, CLASS_NAME, CAT_NAME, SEL_NAME, NUM) \
  do {                                      \
    char *temp;                             \
    sprintf ((BUF), "_%s_%s_%s_%s",         \
             ((IS_INST) ? "i" : "c"),       \
             (CLASS_NAME),                  \
             ((CAT_NAME)? (CAT_NAME) : ""), \
             (SEL_NAME));                   \
    for (temp = (BUF); *temp; temp++)       \
      if (*temp == ':') *temp = '_';        \
  } while (0)
#endif

/* These need specifying.  */
#ifndef OBJC_FORWARDING_STACK_OFFSET
#define OBJC_FORWARDING_STACK_OFFSET 0
#endif

#ifndef OBJC_FORWARDING_MIN_OFFSET
#define OBJC_FORWARDING_MIN_OFFSET 0
#endif
\f
/* Set up for use of obstacks.  */

#include "obstack.h"

/* This obstack is used to accumulate the encoding of a data type.  */
static struct obstack util_obstack;

/* This points to the beginning of obstack contents, so we can free
   the whole contents.  */
char *util_firstobj;

/* The version identifies which language generation and runtime
   the module (file) was compiled for, and is recorded in the
   module descriptor.  */

#define OBJC_VERSION    (flag_next_runtime ? 6 : 8)
#define PROTOCOL_VERSION 2

/* (Decide if these can ever be validly changed.) */
#define OBJC_ENCODE_INLINE_DEFS         0
#define OBJC_ENCODE_DONT_INLINE_DEFS    1

/*** Private Interface (procedures) ***/

/* Used by compile_file.  */

static void init_objc (void);
static void finish_objc (void);

/* Code generation.  */

static tree objc_build_constructor (tree, VEC(constructor_elt,gc) *);
static tree build_objc_method_call (location_t, int, tree, tree, tree, tree);
static tree get_proto_encoding (tree);
static tree lookup_interface (tree);
static tree objc_add_static_instance (tree, tree);

static tree start_class (enum tree_code, tree, tree, tree);
static tree continue_class (tree);
static void finish_class (tree);
static void start_method_def (tree);
#ifdef OBJCPLUS
static void objc_start_function (tree, tree, tree, tree);
#else
static void objc_start_function (tree, tree, tree, struct c_arg_info *);
#endif
static tree start_protocol (enum tree_code, tree, tree);
static tree build_method_decl (enum tree_code, tree, tree, tree, bool);
static tree objc_add_method (tree, tree, int, bool);
static tree add_instance_variable (tree, objc_ivar_visibility_kind, tree);
static tree build_ivar_reference (tree);
static tree is_ivar (tree, tree);

static void build_objc_exception_stuff (void);
static void build_next_objc_exception_stuff (void);

/* We only need the following for ObjC; ObjC++ will use C++'s definition
   of DERIVED_FROM_P.  */
#ifndef OBJCPLUS
static bool objc_derived_from_p (tree, tree);
#define DERIVED_FROM_P(PARENT, CHILD) objc_derived_from_p (PARENT, CHILD)
#endif

/* Property.  */
static void objc_gen_property_data (tree, tree);
static void objc_synthesize_getter (tree, tree, tree);
static void objc_synthesize_setter (tree, tree, tree);
static char *objc_build_property_setter_name (tree);
static int match_proto_with_proto (tree, tree, int);
static tree lookup_property (tree, tree);
static tree lookup_property_in_list (tree, tree);
static tree lookup_property_in_protocol_list (tree, tree);
static void build_objc_property_accessor_helpers (void);

static void objc_xref_basetypes (tree, tree);

static void build_class_template (void);
static void build_selector_template (void);
static void build_category_template (void);
static void build_super_template (void);
static tree build_protocol_initializer (tree, tree, tree, tree, tree);
static tree get_class_ivars (tree, bool);
static tree generate_protocol_list (tree);
static void build_protocol_reference (tree);

static void build_fast_enumeration_state_template (void);

#ifdef OBJCPLUS
static void objc_generate_cxx_cdtors (void);
#endif

/* objc attribute */
static void objc_decl_method_attributes (tree*, tree, int); 
static tree build_keyword_selector (tree);
static const char *synth_id_with_class_suffix (const char *, tree);

/* Hash tables to manage the global pool of method prototypes.  */

hash *nst_method_hash_list = 0;
hash *cls_method_hash_list = 0;

/* Hash tables to manage the global pool of class names.  */

hash *cls_name_hash_list = 0;
hash *als_name_hash_list = 0;

static void hash_class_name_enter (hash *, tree, tree);
static hash hash_class_name_lookup (hash *, tree);

static hash hash_lookup (hash *, tree);
static tree lookup_method (tree, tree);
static tree lookup_method_static (tree, tree, int);

static tree add_class (tree, tree);
static void add_category (tree, tree);
static inline tree lookup_category (tree, tree);

enum string_section
{
  class_names,          /* class, category, protocol, module names */
  meth_var_names,       /* method and variable names */
  meth_var_types        /* method and variable type descriptors */
};

static tree add_objc_string (tree, enum string_section);
static void build_selector_table_decl (void);

/* Protocol additions.  */

static tree lookup_protocol (tree);
static tree lookup_and_install_protocols (tree);

/* Type encoding.  */

static void encode_type_qualifiers (tree);
static void encode_type (tree, int, int);
static void encode_field_decl (tree, int, int);

#ifdef OBJCPLUS
static void really_start_method (tree, tree);
#else
static void really_start_method (tree, struct c_arg_info *);
#endif
static int comp_proto_with_proto (tree, tree, int);
static tree get_arg_type_list (tree, int, int);
static tree objc_decay_parm_type (tree);
static void objc_push_parm (tree);
#ifdef OBJCPLUS
static tree objc_get_parm_info (int);
#else
static struct c_arg_info *objc_get_parm_info (int);
#endif

/* Utilities for debugging and error diagnostics.  */

static char *gen_type_name (tree);
static char *gen_type_name_0 (tree);
static char *gen_method_decl (tree);
static char *gen_declaration (tree);

/* Everything else.  */

static tree create_field_decl (tree, const char *);
static void add_class_reference (tree);
static void build_protocol_template (void);
static tree encode_method_prototype (tree);
static void generate_classref_translation_entry (tree);
static void handle_class_ref (tree);
static void generate_struct_by_value_array (void)
     ATTRIBUTE_NORETURN;
static void mark_referenced_methods (void);
static void generate_objc_image_info (void);
static bool objc_type_valid_for_messaging (tree type, bool allow_classes);

/*** Private Interface (data) ***/

/* Reserved tag definitions.  */

#define OBJECT_TYPEDEF_NAME             "id"
#define CLASS_TYPEDEF_NAME              "Class"

#define TAG_OBJECT                      "objc_object"
#define TAG_CLASS                       "objc_class"
#define TAG_SUPER                       "objc_super"
#define TAG_SELECTOR                    "objc_selector"

#define UTAG_CLASS                      "_objc_class"
#define UTAG_IVAR                       "_objc_ivar"
#define UTAG_IVAR_LIST                  "_objc_ivar_list"
#define UTAG_METHOD                     "_objc_method"
#define UTAG_METHOD_LIST                "_objc_method_list"
#define UTAG_CATEGORY                   "_objc_category"
#define UTAG_MODULE                     "_objc_module"
#define UTAG_SYMTAB                     "_objc_symtab"
#define UTAG_SUPER                      "_objc_super"
#define UTAG_SELECTOR                   "_objc_selector"

#define UTAG_PROTOCOL                   "_objc_protocol"
#define UTAG_METHOD_PROTOTYPE           "_objc_method_prototype"
#define UTAG_METHOD_PROTOTYPE_LIST      "_objc__method_prototype_list"

/* Note that the string object global name is only needed for the
   NeXT runtime.  */
#define STRING_OBJECT_GLOBAL_FORMAT     "_%sClassReference"

#define PROTOCOL_OBJECT_CLASS_NAME      "Protocol"

#define TAG_ENUMERATION_MUTATION        "objc_enumerationMutation"
#define TAG_FAST_ENUMERATION_STATE      "__objcFastEnumerationState"

static const char *TAG_GETCLASS;
static const char *TAG_GETMETACLASS;
static const char *TAG_MSGSEND;
static const char *TAG_MSGSENDSUPER;
/* The NeXT Objective-C messenger may have two extra entry points, for use
   when returning a structure. */
static const char *TAG_MSGSEND_STRET;
static const char *TAG_MSGSENDSUPER_STRET;
static const char *default_constant_string_class_name;

/* Runtime metadata flags.  */
#define CLS_FACTORY                     0x0001L
#define CLS_META                        0x0002L
#define CLS_HAS_CXX_STRUCTORS           0x2000L

#define OBJC_MODIFIER_STATIC            0x00000001
#define OBJC_MODIFIER_FINAL             0x00000002
#define OBJC_MODIFIER_PUBLIC            0x00000004
#define OBJC_MODIFIER_PRIVATE           0x00000008
#define OBJC_MODIFIER_PROTECTED         0x00000010
#define OBJC_MODIFIER_NATIVE            0x00000020
#define OBJC_MODIFIER_SYNCHRONIZED      0x00000040
#define OBJC_MODIFIER_ABSTRACT          0x00000080
#define OBJC_MODIFIER_VOLATILE          0x00000100
#define OBJC_MODIFIER_TRANSIENT         0x00000200
#define OBJC_MODIFIER_NONE_SPECIFIED    0x80000000

/* NeXT-specific tags.  */

#define TAG_MSGSEND_NONNIL              "objc_msgSendNonNil"
#define TAG_MSGSEND_NONNIL_STRET        "objc_msgSendNonNil_stret"
#define TAG_EXCEPTIONEXTRACT            "objc_exception_extract"
#define TAG_EXCEPTIONTRYENTER           "objc_exception_try_enter"
#define TAG_EXCEPTIONTRYEXIT            "objc_exception_try_exit"
#define TAG_EXCEPTIONMATCH              "objc_exception_match"
#define TAG_EXCEPTIONTHROW              "objc_exception_throw"
#define TAG_SYNCENTER                   "objc_sync_enter"
#define TAG_SYNCEXIT                    "objc_sync_exit"
#define TAG_SETJMP                      "_setjmp"
#define UTAG_EXCDATA                    "_objc_exception_data"

#define TAG_ASSIGNIVAR                  "objc_assign_ivar"
#define TAG_ASSIGNGLOBAL                "objc_assign_global"
#define TAG_ASSIGNSTRONGCAST            "objc_assign_strongCast"

/* Branch entry points.  All that matters here are the addresses;
   functions with these names do not really exist in libobjc.  */

#define TAG_MSGSEND_FAST                "objc_msgSend_Fast"
#define TAG_ASSIGNIVAR_FAST             "objc_assign_ivar_Fast"

#define TAG_CXX_CONSTRUCT               ".cxx_construct"
#define TAG_CXX_DESTRUCT                ".cxx_destruct"

/* GNU-specific tags.  */

#define TAG_EXECCLASS                   "__objc_exec_class"
#define TAG_GNUINIT                     "__objc_gnu_init"

/* Flags for lookup_method_static().  */

/* Look for class methods.  */
#define OBJC_LOOKUP_CLASS       1
/* Do not examine superclasses.  */
#define OBJC_LOOKUP_NO_SUPER    2
/* Disable returning an instance method of a root class when a class
   method can't be found.  */
#define OBJC_LOOKUP_NO_INSTANCE_METHODS_OF_ROOT_CLASS 4 

/* The OCTI_... enumeration itself is in objc/objc-act.h.  */
tree objc_global_trees[OCTI_MAX];

static void handle_impent (struct imp_entry *);

struct imp_entry *imp_list = 0;
int imp_count = 0;      /* `@implementation' */
int cat_count = 0;      /* `@category' */

objc_ivar_visibility_kind objc_ivar_visibility;

/* Use to generate method labels.  */
static int method_slot = 0;

/* Flag to say whether methods in a protocol are optional or
   required.  */
static bool objc_method_optional_flag = false;

static int objc_collecting_ivars = 0;

#define BUFSIZE         1024

static char *errbuf;    /* Buffer for error diagnostics */

/* Data imported from tree.c.  */

extern enum debug_info_type write_symbols;

\f
static int flag_typed_selectors;

/* Store all constructed constant strings in a hash table so that
   they get uniqued properly.  */

struct GTY(()) string_descriptor {
  /* The literal argument .  */
  tree literal;

  /* The resulting constant string.  */
  tree constructor;
};

static GTY((param_is (struct string_descriptor))) htab_t string_htab;

FILE *gen_declaration_file;

/* Tells "encode_pointer/encode_aggregate" whether we are generating
   type descriptors for instance variables (as opposed to methods).
   Type descriptors for instance variables contain more information
   than methods (for static typing and embedded structures).  */

static int generating_instance_variables = 0;

/* For building an objc struct.  These may not be used when this file
   is compiled as part of obj-c++.  */

static bool objc_building_struct;
static struct c_struct_parse_info *objc_struct_info ATTRIBUTE_UNUSED;

/* Start building a struct for objc.  */

static tree
objc_start_struct (tree name)
{
  gcc_assert (!objc_building_struct);
  objc_building_struct = true;
  return start_struct (input_location, RECORD_TYPE, name, &objc_struct_info);
}

/* Finish building a struct for objc.  */

static tree
objc_finish_struct (tree type, tree fieldlist)
{
  gcc_assert (objc_building_struct);
  objc_building_struct = false;
  return finish_struct (input_location, type, fieldlist, NULL_TREE,
                        objc_struct_info);
}

static tree
build_sized_array_type (tree base_type, int size)
{
  tree index_type = build_index_type (build_int_cst (NULL_TREE, size - 1));
  return build_array_type (base_type, index_type);
}

static tree
add_field_decl (tree type, const char *name, tree **chain)
{
  tree field = create_field_decl (type, name);

  if (*chain != NULL)
    **chain = field;
  *chain = &DECL_CHAIN (field);

  return field;
}

/* Create a temporary variable of type 'type'.  If 'name' is set, uses
   the specified name, else use no name.  Returns the declaration of
   the type.  The 'name' is mostly useful for debugging.
*/
static tree
objc_create_temporary_var (tree type, const char *name)
{
  tree decl;

  if (name != NULL)
    {
      decl = build_decl (input_location,
                         VAR_DECL, get_identifier (name), type);
    }
  else
    {
      decl = build_decl (input_location,
                         VAR_DECL, NULL_TREE, type);
    }
  TREE_USED (decl) = 1;
  DECL_ARTIFICIAL (decl) = 1;
  DECL_IGNORED_P (decl) = 1;
  DECL_CONTEXT (decl) = current_function_decl;

  return decl;
}

/* Some platforms pass small structures through registers versus
   through an invisible pointer.  Determine at what size structure is
   the transition point between the two possibilities.  */

static void
generate_struct_by_value_array (void)
{
  tree type;
  tree decls;
  int i, j;
  int aggregate_in_mem[32];
  int found = 0;

  /* Presumably no platform passes 32 byte structures in a register.  */
  for (i = 1; i < 32; i++)
    {
      char buffer[5];
      tree *chain = NULL;

      /* Create an unnamed struct that has `i' character components */
      type = objc_start_struct (NULL_TREE);

      strcpy (buffer, "c1");
      decls = add_field_decl (char_type_node, buffer, &chain);

      for (j = 1; j < i; j++)
        {
          sprintf (buffer, "c%d", j + 1);
          add_field_decl (char_type_node, buffer, &chain);
        }
      objc_finish_struct (type, decls);

      aggregate_in_mem[i] = aggregate_value_p (type, 0);
      if (!aggregate_in_mem[i])
        found = 1;
    }

  /* We found some structures that are returned in registers instead of memory
     so output the necessary data.  */
  if (found)
    {
      for (i = 31; i >= 0;  i--)
        if (!aggregate_in_mem[i])
          break;
      printf ("#define OBJC_MAX_STRUCT_BY_VALUE %d\n\n", i);

      /* The first member of the structure is always 0 because we don't handle
         structures with 0 members */
      printf ("static int struct_forward_array[] = {\n  0");

      for (j = 1; j <= i; j++)
        printf (", %d", aggregate_in_mem[j]);
      printf ("\n};\n");
    }

  exit (0);
}

bool
objc_init (void)
{
#ifdef OBJCPLUS
  if (cxx_init () == false)
#else
  if (c_objc_common_init () == false)
#endif
    return false;

  /* If gen_declaration desired, open the output file.  */
  if (flag_gen_declaration)
    {
      register char * const dumpname = concat (dump_base_name, ".decl", NULL);
      gen_declaration_file = fopen (dumpname, "w");
      if (gen_declaration_file == 0)
        fatal_error ("can%'t open %s: %m", dumpname);
      free (dumpname);
    }

  if (flag_next_runtime)
    {
      TAG_GETCLASS = "objc_getClass";
      TAG_GETMETACLASS = "objc_getMetaClass";
      TAG_MSGSEND = "objc_msgSend";
      TAG_MSGSENDSUPER = "objc_msgSendSuper";
      TAG_MSGSEND_STRET = "objc_msgSend_stret";
      TAG_MSGSENDSUPER_STRET = "objc_msgSendSuper_stret";
      default_constant_string_class_name = "NSConstantString";
    }
  else
    {
      TAG_GETCLASS = "objc_get_class";
      TAG_GETMETACLASS = "objc_get_meta_class";
      TAG_MSGSEND = "objc_msg_lookup";
      TAG_MSGSENDSUPER = "objc_msg_lookup_super";
      /* GNU runtime does not provide special functions to support
         structure-returning methods.  */
      default_constant_string_class_name = "NXConstantString";
      flag_typed_selectors = 1;
      /* GNU runtime does not need the compiler to change code
         in order to do GC. */
      if (flag_objc_gc)
        {
          warning_at (0, 0, "%<-fobjc-gc%> is ignored for %<-fgnu-runtime%>");
          flag_objc_gc=0;
        }
    }

  init_objc ();

  if (print_struct_values && !flag_compare_debug)
    generate_struct_by_value_array ();

  return true;
}

/* This is called automatically (at the very end of compilation) by
   c_write_global_declarations and cp_write_global_declarations.  */
void
objc_write_global_declarations (void)
{
  mark_referenced_methods ();

  /* Finalize Objective-C runtime data.  */
  finish_objc ();

  if (gen_declaration_file)
    fclose (gen_declaration_file);
}
\f
/* Return the first occurrence of a method declaration corresponding
   to sel_name in rproto_list.  Search rproto_list recursively.
   If is_class is 0, search for instance methods, otherwise for class
   methods.  */
static tree
lookup_method_in_protocol_list (tree rproto_list, tree sel_name,
                                int is_class)
{
   tree rproto, p;
   tree fnd = 0;

   for (rproto = rproto_list; rproto; rproto = TREE_CHAIN (rproto))
     {
        p = TREE_VALUE (rproto);

        if (TREE_CODE (p) == PROTOCOL_INTERFACE_TYPE)
          {
            if ((fnd = lookup_method (is_class
                                      ? PROTOCOL_CLS_METHODS (p)
                                      : PROTOCOL_NST_METHODS (p), sel_name)))
              ;
            else if (PROTOCOL_LIST (p))
              fnd = lookup_method_in_protocol_list (PROTOCOL_LIST (p),
                                                    sel_name, is_class);
          }
        else
          {
            ; /* An identifier...if we could not find a protocol.  */
          }

        if (fnd)
          return fnd;
     }

   return 0;
}

static tree
lookup_protocol_in_reflist (tree rproto_list, tree lproto)
{
  tree rproto, p;

  /* Make sure the protocol is supported by the object on the rhs.  */
  if (TREE_CODE (lproto) == PROTOCOL_INTERFACE_TYPE)
    {
      tree fnd = 0;
      for (rproto = rproto_list; rproto; rproto = TREE_CHAIN (rproto))
        {
          p = TREE_VALUE (rproto);

          if (TREE_CODE (p) == PROTOCOL_INTERFACE_TYPE)
            {
              if (lproto == p)
                fnd = lproto;

              else if (PROTOCOL_LIST (p))
                fnd = lookup_protocol_in_reflist (PROTOCOL_LIST (p), lproto);
            }

          if (fnd)
            return fnd;
        }
    }
  else
    {
      ; /* An identifier...if we could not find a protocol.  */
    }

  return 0;
}

void
objc_start_class_interface (tree klass, tree super_class,
                            tree protos, tree attributes)
{
  if (attributes)
    {
      if (flag_objc1_only)
        error_at (input_location, "class attributes are not available in Objective-C 1.0");
      else
        warning_at (input_location, OPT_Wattributes, 
                    "class attributes are not available in this version"
                    " of the compiler, (ignored)");
    }
  objc_interface_context
    = objc_ivar_context
    = start_class (CLASS_INTERFACE_TYPE, klass, super_class, protos);
  objc_ivar_visibility = OBJC_IVAR_VIS_PROTECTED;
}

void
objc_start_category_interface (tree klass, tree categ,
                               tree protos, tree attributes)
{
  if (attributes)
    {
      if (flag_objc1_only)
        error_at (input_location, "category attributes are not available in Objective-C 1.0");
      else
        warning_at (input_location, OPT_Wattributes, 
                    "category attributes are not available in this version"
                    " of the compiler, (ignored)");
    }
  objc_interface_context
    = start_class (CATEGORY_INTERFACE_TYPE, klass, categ, protos);
  objc_ivar_chain
    = continue_class (objc_interface_context);
}

void
objc_start_protocol (tree name, tree protos, tree attributes)
{
  if (attributes)
    {
      if (flag_objc1_only)
        error_at (input_location, "protocol attributes are not available in Objective-C 1.0");  
      else
        warning_at (input_location, OPT_Wattributes, 
                    "protocol attributes are not available in this version"
                    " of the compiler, (ignored)");
    }
  objc_interface_context
    = start_protocol (PROTOCOL_INTERFACE_TYPE, name, protos);
  objc_method_optional_flag = false;
}

void
objc_continue_interface (void)
{
  objc_ivar_chain
    = continue_class (objc_interface_context);
}

void
objc_finish_interface (void)
{
  finish_class (objc_interface_context);
  objc_interface_context = NULL_TREE;
  objc_method_optional_flag = false;
}

void
objc_start_class_implementation (tree klass, tree super_class)
{
  objc_implementation_context
    = objc_ivar_context
    = start_class (CLASS_IMPLEMENTATION_TYPE, klass, super_class, NULL_TREE);
  objc_ivar_visibility = OBJC_IVAR_VIS_PROTECTED;
}

void
objc_start_category_implementation (tree klass, tree categ)
{
  objc_implementation_context
    = start_class (CATEGORY_IMPLEMENTATION_TYPE, klass, categ, NULL_TREE);
  objc_ivar_chain
    = continue_class (objc_implementation_context);
}

void
objc_continue_implementation (void)
{
  objc_ivar_chain
    = continue_class (objc_implementation_context);
}

void
objc_finish_implementation (void)
{
#ifdef OBJCPLUS
  if (flag_objc_call_cxx_cdtors)
    objc_generate_cxx_cdtors ();
#endif

  if (objc_implementation_context)
    {
      finish_class (objc_implementation_context);
      objc_ivar_chain = NULL_TREE;
      objc_implementation_context = NULL_TREE;
    }
  else
    warning (0, "%<@end%> must appear in an @implementation context");
}

void
objc_set_visibility (objc_ivar_visibility_kind visibility)
{
  if (visibility == OBJC_IVAR_VIS_PACKAGE)
    {
      if (flag_objc1_only)
        error ("%<@package%> is not available in Objective-C 1.0");
      else
        warning (0, "%<@package%> presently has the same effect as %<@public%>");
    }
  objc_ivar_visibility = visibility;
}

void
objc_set_method_opt (bool optional)
{
  if (flag_objc1_only)
    error_at (input_location, "@optional/@required are not available in Objective-C 1.0");      

  objc_method_optional_flag = optional;
  if (!objc_interface_context 
      || TREE_CODE (objc_interface_context) != PROTOCOL_INTERFACE_TYPE)
    {
      error ("@optional/@required is allowed in @protocol context only");
      objc_method_optional_flag = false;
    }
}

/* This routine looks for a given PROPERTY in a list of CLASS, CATEGORY, or
   PROTOCOL.  */
static tree
lookup_property_in_list (tree chain, tree property)
{
  tree x;
  for (x = CLASS_PROPERTY_DECL (chain); x; x = TREE_CHAIN (x))
    if (PROPERTY_NAME (x) == property)
      return x;
  return NULL_TREE;
}

/* This routine looks for a given PROPERTY in the tree chain of RPROTO_LIST. */
static tree lookup_property_in_protocol_list (tree rproto_list, tree property)
{
  tree rproto, x;
  for (rproto = rproto_list; rproto; rproto = TREE_CHAIN (rproto))
    {
      tree p = TREE_VALUE (rproto);
      if (TREE_CODE (p) == PROTOCOL_INTERFACE_TYPE)
        {
          if ((x = lookup_property_in_list (p, property)))
            return x;
          if (PROTOCOL_LIST (p))
            return lookup_property_in_protocol_list (PROTOCOL_LIST (p), property);
        }
      else
        {
          ; /* An identifier...if we could not find a protocol.  */
        }
    }
  return NULL_TREE;
}

/* This routine looks up the PROPERTY in current INTERFACE, its categories and up the
   chain of interface hierarchy.  */
static tree
lookup_property (tree interface_type, tree property)
{
  tree inter = interface_type;
  while (inter)
    {
      tree x, category;
      if ((x = lookup_property_in_list (inter, property)))
        return x;
      /* Failing that, look for the property in each category of the class.  */
      category = inter;
      while ((category = CLASS_CATEGORY_LIST (category)))
        {
          if ((x = lookup_property_in_list (category, property)))
            return x;

          /* When checking a category, also check the protocols
             attached with the category itself.  */
          if (CLASS_PROTOCOL_LIST (category)
              && (x = lookup_property_in_protocol_list
                  (CLASS_PROTOCOL_LIST (category), property)))
            return x;
        }

      /*  Failing to find in categories, look for property in protocol list. */
      if (CLASS_PROTOCOL_LIST (inter) 
          && (x = lookup_property_in_protocol_list
              (CLASS_PROTOCOL_LIST (inter), property)))
        return x;
      
      /* Failing that, climb up the inheritance hierarchy.  */
      inter = lookup_interface (CLASS_SUPER_NAME (inter));
    }
  return inter;
}

/* This routine is called by the parser when a
   @property... declaration is found.  'decl' is the declaration of
   the property (type/identifier), and the other arguments represent
   property attributes that may have been specified in the Objective-C
   declaration.  'parsed_property_readonly' is 'true' if the attribute
   'readonly' was specified, and 'false' if not; similarly for the
   other bool parameters.  'parsed_property_getter_ident' is NULL_TREE
   if the attribute 'getter' was not specified, and is the identifier
   corresponding to the specified getter if it was; similarly for
   'parsed_property_setter_ident'.  */
void
objc_add_property_declaration (location_t location, tree decl,
                               bool parsed_property_readonly, bool parsed_property_readwrite,
                               bool parsed_property_assign, bool parsed_property_retain,
                               bool parsed_property_copy, bool parsed_property_nonatomic,
                               tree parsed_property_getter_ident, tree parsed_property_setter_ident)
{
  tree property_decl;
  tree x;
  /* 'property_readonly' and 'property_assign_semantics' are the final
     attributes of the property after all parsed attributes have been
     considered (eg, if we parsed no 'readonly' and no 'readwrite', ie
     parsed_property_readonly = false and parsed_property_readwrite =
     false, then property_readonly will be false because the default
     is readwrite).  */
  bool property_readonly = false;
  objc_property_assign_semantics property_assign_semantics = OBJC_PROPERTY_ASSIGN;

  if (flag_objc1_only)
    error_at (input_location, "%<@property%> is not available in Objective-C 1.0");

  if (parsed_property_readonly && parsed_property_readwrite)
    {
      error_at (location, "%<readonly%> attribute conflicts with %<readwrite%> attribute");
      /* In case of conflicting attributes (here and below), after
         producing an error, we pick one of the attributes and keep
         going.  */
      property_readonly = false;
    }
  else
    {
      if (parsed_property_readonly)
        property_readonly = true;
  
      if (parsed_property_readwrite)
        property_readonly = false;
    }

  if (parsed_property_readonly && parsed_property_setter_ident)
    {
      error_at (location, "%<readonly%> attribute conflicts with %<setter%> attribute");
      property_readonly = false;
    }

  if (parsed_property_assign && parsed_property_retain)
    {
      error_at (location, "%<assign%> attribute conflicts with %<retain%> attribute");
      property_assign_semantics = OBJC_PROPERTY_RETAIN;
    }
  else if (parsed_property_assign && parsed_property_copy)
    {
      error_at (location, "%<assign%> attribute conflicts with %<copy%> attribute");
      property_assign_semantics = OBJC_PROPERTY_COPY;
    }
  else if (parsed_property_retain && parsed_property_copy)
    {
      error_at (location, "%<retain%> attribute conflicts with %<copy%> attribute");
      property_assign_semantics = OBJC_PROPERTY_COPY;
    }
  else
    {
      if (parsed_property_assign)
        property_assign_semantics = OBJC_PROPERTY_ASSIGN;

      if (parsed_property_retain)
        property_assign_semantics = OBJC_PROPERTY_RETAIN;

      if (parsed_property_copy)
        property_assign_semantics = OBJC_PROPERTY_COPY;
    }

  if (!objc_interface_context)
    {
      error_at (location, "property declaration not in @interface or @protocol context");
      return;
    }

  /* At this point we know that we are either in an interface, a
     category, or a protocol.  */

  /* We expect a FIELD_DECL from the parser.  Make sure we didn't get
     something else, as that would confuse the checks below.  */
  if (TREE_CODE (decl) != FIELD_DECL)
    {
      error_at (location, "invalid property declaration");
      return;      
    }

  /* Do some spot-checks for the most obvious invalid types.  */

  if (TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE)
    {
      error_at (location, "property can not be an array");
      return;
    }

  /* The C++/ObjC++ parser seems to reject the ':' for a bitfield when
     parsing, while the C/ObjC parser accepts it and gives us a
     FIELD_DECL with a DECL_INITIAL set.  So we use the DECL_INITIAL
     to check for a bitfield when doing ObjC.  */
#ifndef OBJCPLUS
  if (DECL_INITIAL (decl))
    {
      /* A @property is not an actual variable, but it is a way to
         describe a pair of accessor methods, so its type (which is
         the type of the return value of the getter and the first
         argument of the setter) can't be a bitfield (as return values
         and arguments of functions can not be bitfields).  The
         underlying instance variable could be a bitfield, but that is
         a different matter.  */
      error_at (location, "property can not be a bit-field");
      return;      
    }
#endif

  /* TODO: Check that the property type is an Objective-C object or a
     "POD".  */

  /* Implement -Wproperty-assign-default (which is enabled by default).  */
  if (warn_property_assign_default
      /* If garbage collection is not being used, then 'assign' is
         valid for objects (and typically used for delegates) but it
         is wrong in most cases (since most objects need to be
         retained or copied in setters).  Warn users when 'assign' is
         used implicitly.  */
      && property_assign_semantics == OBJC_PROPERTY_ASSIGN
      /* Read-only properties are never assigned, so the assignment
         semantics do not matter in that case.  */
      && !property_readonly
      && !flag_objc_gc)
    {
      /* Please note that it would make sense to default to 'assign'
         for non-{Objective-C objects}, and to 'retain' for
         Objective-C objects.  But that would break compatibility with
         other compilers.  */
      if (!parsed_property_assign && !parsed_property_retain && !parsed_property_copy)
        {
          /* Use 'false' so we do not warn for Class objects.  */
          if (objc_type_valid_for_messaging (TREE_TYPE (decl), false))
            {
              warning_at (location, 
                          0,
                          "object property %qD has no %<assign%>, %<retain%> or %<copy%> attribute; assuming %<assign%>", 
                          decl);
              inform (location, 
                      "%<assign%> can be unsafe for Objective-C objects; please state explicitly if you need it");
            }
        }
    }
  
  if (property_assign_semantics == OBJC_PROPERTY_RETAIN
      && !objc_type_valid_for_messaging (TREE_TYPE (decl), true))
    error_at (location, "%<retain%> attribute is only valid for Objective-C objects");
  
  if (property_assign_semantics == OBJC_PROPERTY_COPY
      && !objc_type_valid_for_messaging (TREE_TYPE (decl), true))
    error_at (location, "%<copy%> attribute is only valid for Objective-C objects");

  /* Now determine the final property getter and setter names.  They
     will be stored in the PROPERTY_DECL, from which they'll always be
     extracted and used.  */

  /* Adjust, or fill in, setter and getter names.  We overwrite the
     parsed_property_setter_ident and parsed_property_getter_ident
     with the final setter and getter identifiers that will be
     used.  */
  if (parsed_property_setter_ident)
    {
      /* The setter should be terminated by ':', but the parser only
         gives us an identifier without ':'.  So, we need to add ':'
         at the end.  */
      const char *parsed_setter = IDENTIFIER_POINTER (parsed_property_setter_ident);
      size_t length = strlen (parsed_setter);
      char *final_setter = (char *)alloca (length + 2);

      sprintf (final_setter, "%s:", parsed_setter);
      parsed_property_setter_ident = get_identifier (final_setter);
    }
  else
    {
      if (!property_readonly)
        parsed_property_setter_ident = get_identifier (objc_build_property_setter_name 
                                                       (DECL_NAME (decl)));
    }

  if (!parsed_property_getter_ident)
    parsed_property_getter_ident = DECL_NAME (decl);

  /* Check for duplicate property declarations.  We first check the
     immediate context for a property with the same name.  Any such
     declarations are an error.  */
  for (x = CLASS_PROPERTY_DECL (objc_interface_context); x; x = TREE_CHAIN (x))
    {
      if (PROPERTY_NAME (x) == DECL_NAME (decl))
        {
          location_t original_location = DECL_SOURCE_LOCATION (x);
          
          error_at (location, "redeclaration of property %qD", decl);

          if (original_location != UNKNOWN_LOCATION)
            inform (original_location, "originally specified here");
          return;
      }
    }

  /* We now need to check for existing property declarations (in the
     superclass, other categories or protocols) and check that the new
     declaration is not in conflict with existing ones.  */

  /* Search for a previous, existing declaration of a property with
     the same name in superclasses, protocols etc.  If one is found,
     it will be in the 'x' variable.  */
  x = NULL_TREE;

  /* Note that, for simplicity, the following may search again the
     local context.  That's Ok as nothing will be found (else we'd
     have thrown an error above); it's only a little inefficient, but
     the code is simpler.  */
  switch (TREE_CODE (objc_interface_context))
    {
    case CLASS_INTERFACE_TYPE:
      /* Look up the property in the current @interface (which will
         find nothing), then its protocols and categories and
         superclasses.  */
      x = lookup_property (objc_interface_context, DECL_NAME (decl));
      break;
    case CATEGORY_INTERFACE_TYPE:
      /* Look up the property in the main @interface, then protocols
         and categories (one of them is ours, and will find nothing)
         and superclasses.  */
      x = lookup_property (lookup_interface (CLASS_NAME (objc_interface_context)),
                           DECL_NAME (decl));
      break;
    case PROTOCOL_INTERFACE_TYPE:
      /* Looks up the property in any protocols attached to the
         current protocol.  */
      if (PROTOCOL_LIST (objc_interface_context))
        {
          x = lookup_property_in_protocol_list (PROTOCOL_LIST (objc_interface_context),
                                                DECL_NAME (decl));
        }
      break;
    default:
      gcc_unreachable ();
    }

  if (x != NULL_TREE)
    {
      /* An existing property was found; check that it has the same
         types, or it is compatible.  */
      location_t original_location = DECL_SOURCE_LOCATION (x);
          
      if (PROPERTY_NONATOMIC (x) != parsed_property_nonatomic)
        {
          warning_at (location, 0,
                      "'nonatomic' attribute of property %qD conflicts with previous declaration", decl);
      
          if (original_location != UNKNOWN_LOCATION)
            inform (original_location, "originally specified here");
          return;
        }

      if (PROPERTY_GETTER_NAME (x) != parsed_property_getter_ident)
        {
          warning_at (location, 0,
                      "'getter' attribute of property %qD conflicts with previous declaration", decl);
      
          if (original_location != UNKNOWN_LOCATION)
            inform (original_location, "originally specified here");
          return;
        }

      /* We can only compare the setter names if both the old and new property have a setter.  */
      if (!property_readonly  &&  !PROPERTY_READONLY(x))
        {
          if (PROPERTY_SETTER_NAME (x) != parsed_property_setter_ident)
            {
              warning_at (location, 0,
                          "'setter' attribute of property %qD conflicts with previous declaration", decl);
              
              if (original_location != UNKNOWN_LOCATION)
                inform (original_location, "originally specified here");
              return;
            }
        }

      if (PROPERTY_ASSIGN_SEMANTICS (x) != property_assign_semantics)
        {
          warning_at (location, 0,
                      "assign semantics attributes of property %qD conflict with previous declaration", decl);
      
          if (original_location != UNKNOWN_LOCATION)
            inform (original_location, "originally specified here");
          return;
        }

      /* It's ok to have a readonly property that becomes a readwrite, but not vice versa.  */
      if (PROPERTY_READONLY (x) == 0  &&  property_readonly == 1)
        {
          warning_at (location, 0,
                      "'readonly' attribute of property %qD conflicts with previous declaration", decl);
      
          if (original_location != UNKNOWN_LOCATION)
            inform (original_location, "originally specified here");
          return;
        }

      /* We now check that the new and old property declarations have
         the same types (or compatible one).  In the Objective-C
         tradition of loose type checking, we do type-checking but
         only generate warnings (not errors) if they do not match.
         For non-readonly properties, the types must match exactly;
         for readonly properties, it is allowed to use a "more
         specialized" type in the new property declaration.  Eg, the
         superclass has a getter returning (NSArray *) and the
         subclass a getter returning (NSMutableArray *).  The object's
         getter returns an (NSMutableArray *); but if you cast the
         object to the superclass, which is allowed, you'd still
         expect the getter to return an (NSArray *), which works since
         an (NSMutableArray *) is an (NSArray *) too.  So, the set of
         objects belonging to the type of the new @property should be
         a subset of the set of objects belonging to the type of the
         old @property.  This is what "specialization" means.  And the
         reason it only applies to readonly properties is that for a
         readwrite property the setter would have the opposite
         requirement - ie that the superclass type is more specialized
         then the subclass one; hence the only way to satisfy both
         constraints is that the types match.  */

      /* If the types are not the same in the C sense, we warn ...  */
      if (!comptypes (TREE_TYPE (x), TREE_TYPE (decl))
          /* ... unless the property is readonly, in which case we
             allow a new, more specialized, declaration.  */
          && (!property_readonly 
              || !objc_compare_types (TREE_TYPE (x),
                                      TREE_TYPE (decl), -5, NULL_TREE)))
        {
          warning_at (location, 0,
                      "type of property %qD conflicts with previous declaration", decl);
          if (original_location != UNKNOWN_LOCATION)
            inform (original_location, "originally specified here");
          return;
        }
    }

  /* Create a PROPERTY_DECL node.  */
  property_decl = make_node (PROPERTY_DECL);

  /* Copy the basic information from the original decl.  */
  TREE_TYPE (property_decl) = TREE_TYPE (decl);
  DECL_SOURCE_LOCATION (property_decl) = DECL_SOURCE_LOCATION (decl);
  TREE_DEPRECATED (property_decl) = TREE_DEPRECATED (decl);
  
  /* Add property-specific information.  */
  PROPERTY_NAME (property_decl) = DECL_NAME (decl);
  PROPERTY_GETTER_NAME (property_decl) = parsed_property_getter_ident;
  PROPERTY_SETTER_NAME (property_decl) = parsed_property_setter_ident;
  PROPERTY_READONLY (property_decl) = property_readonly;
  PROPERTY_NONATOMIC (property_decl) = parsed_property_nonatomic;
  PROPERTY_ASSIGN_SEMANTICS (property_decl) = property_assign_semantics;
  PROPERTY_IVAR_NAME (property_decl) = NULL_TREE;
  PROPERTY_DYNAMIC (property_decl) = 0;

  /* Note that PROPERTY_GETTER_NAME is always set for all
     PROPERTY_DECLs, and PROPERTY_SETTER_NAME is always set for all
     PROPERTY_DECLs where PROPERTY_READONLY == 0.  Any time we deal
     with a getter or setter, we should get the PROPERTY_DECL and use
     PROPERTY_GETTER_NAME and PROPERTY_SETTER_NAME to know the correct
     names.  */

  /* Add the PROPERTY_DECL to the list of properties for the class.  */
  TREE_CHAIN (property_decl) = CLASS_PROPERTY_DECL (objc_interface_context);
  CLASS_PROPERTY_DECL (objc_interface_context) = property_decl;
}

/* This is a subroutine of objc_maybe_build_component_ref.  Search the
   list of methods in the interface (and, failing that, the local list
   in the implementation, and failing that, the protocol list)
   provided for a 'setter' or 'getter' for 'component' with default
   names (ie, if 'component' is "name", then search for "name" and
   "setName:").  If any is found, then create an artificial property
   that uses them.  Return NULL_TREE if 'getter' or 'setter' could not
   be found.  */
static tree
maybe_make_artificial_property_decl (tree interface, tree implementation, 
                                     tree protocol_list, tree component, bool is_class)
{
  tree getter_name = component;
  tree setter_name = get_identifier (objc_build_property_setter_name (component));
  tree getter = NULL_TREE;
  tree setter = NULL_TREE;

  /* First, check the @interface and all superclasses.  */
  if (interface)
    {
      int flags = 0;

      /* Using instance methods of the root class as accessors is most
         likely unwanted and can be extremely confusing (and, most
         importantly, other Objective-C 2.0 compilers do not do it).
         Turn it off.  */
      if (is_class)
        flags = OBJC_LOOKUP_CLASS | OBJC_LOOKUP_NO_INSTANCE_METHODS_OF_ROOT_CLASS;
      
      getter = lookup_method_static (interface, getter_name, flags);
      setter = lookup_method_static (interface, setter_name, flags);
    }

  /* Second, check the local @implementation context.  */
  if (!getter && !setter)
    {
      if (implementation)
        {
          if (is_class)
            {
              getter = lookup_method (CLASS_CLS_METHODS (implementation), getter_name);
              setter = lookup_method (CLASS_CLS_METHODS (implementation), setter_name);
            }
          else
            {
              getter = lookup_method (CLASS_NST_METHODS (implementation), getter_name);
              setter = lookup_method (CLASS_NST_METHODS (implementation), setter_name);       
            }
        }
    }

  /* Try the protocol_list if we didn't find anything in the
     @interface and in the @implementation.  */
  if (!getter && !setter)
    {
      getter = lookup_method_in_protocol_list (protocol_list, getter_name, is_class);
      setter = lookup_method_in_protocol_list (protocol_list, setter_name, is_class);
    }

  /* There needs to be at least a getter or setter for this to be a
     valid 'object.component' syntax.  */
  if (getter || setter)
    {
      /* Yes ... determine the type of the expression.  */
      tree property_decl;
      tree type;
      
      if (getter)
        type = TREE_VALUE (TREE_TYPE (getter));
      else
        type = TREE_VALUE (TREE_TYPE (METHOD_SEL_ARGS (setter)));
      
      /* Create an artificial property declaration with the
         information we collected on the type and getter/setter
         names.  */
      property_decl = make_node (PROPERTY_DECL);
      
      TREE_TYPE (property_decl) = type;
      DECL_SOURCE_LOCATION (property_decl) = input_location;
      TREE_DEPRECATED (property_decl) = 0;
      DECL_ARTIFICIAL (property_decl) = 1;
              
      /* Add property-specific information.  Note that one of
         PROPERTY_GETTER_NAME or PROPERTY_SETTER_NAME may refer to a
         non-existing method; this will generate an error when the
         expression is later compiled.  At this stage we don't know if
         the getter or setter will be used, so we can't generate an
         error.  */
      PROPERTY_NAME (property_decl) = component;
      PROPERTY_GETTER_NAME (property_decl) = getter_name;
      PROPERTY_SETTER_NAME (property_decl) = setter_name;
      PROPERTY_READONLY (property_decl) = 0;
      PROPERTY_NONATOMIC (property_decl) = 0;
      PROPERTY_ASSIGN_SEMANTICS (property_decl) = 0;
      PROPERTY_IVAR_NAME (property_decl) = NULL_TREE;
      PROPERTY_DYNAMIC (property_decl) = 0;

      if (!getter)
        PROPERTY_HAS_NO_GETTER (property_decl) = 1;

      /* The following is currently unused, but it's nice to have
         there.  We may use it if we need in the future.  */
      if (!setter)
        PROPERTY_HAS_NO_SETTER (property_decl) = 1;

      return property_decl;
    }

  return NULL_TREE;
}

/* This hook routine is invoked by the parser when an expression such
   as 'xxx.yyy' is parsed.  We get a chance to process these
   expressions in a way that is specified to Objective-C (to implement
   the Objective-C 2.0 dot-syntax, properties, or non-fragile ivars).
   If the expression is not an Objective-C specified expression, we
   should return NULL_TREE; else we return the expression.

   At the moment this only implements dot-syntax and properties (not
   non-fragile ivars yet), ie 'object.property' or 'object.component'
   where 'component' is not a declared property, but a valid getter or
   setter for it could be found.  */
tree
objc_maybe_build_component_ref (tree object, tree property_ident)
{
  tree x = NULL_TREE;
  tree rtype;

  /* If we are in Objective-C 1.0 mode, dot-syntax and properties are
     not available.  */
  if (flag_objc1_only)
    return NULL_TREE;

  /* Try to determine if 'object' is an Objective-C object or not.  If
     not, return.  */
  if (object == NULL_TREE || object == error_mark_node 
      || (rtype = TREE_TYPE (object)) == NULL_TREE)
    return NULL_TREE;
  
  if (property_ident == NULL_TREE || property_ident == error_mark_node
      || TREE_CODE (property_ident) != IDENTIFIER_NODE)
    return NULL_TREE;

  /* The following analysis of 'object' is similar to the one used for
     the 'receiver' of a method invocation.  We need to determine what
     'object' is and find the appropriate property (either declared,
     or artificial) for it (in the same way as we need to find the
     appropriate method prototype for a method invocation).  There are
     some simplifications here though: "object.property" is invalid if
     "object" has a type of "id" or "Class"; it must at least have a
     protocol attached to it, and "object" is never a class name as
     that is done by objc_build_class_component_ref.  Finally, we
     don't know if this really is a dot-syntax expression, so we want
     to make a quick exit if it is not; for this reason, we try to
     postpone checks after determining that 'object' looks like an
     Objective-C object.  */

  if (objc_is_id (rtype))
    {
      /* This is the case that the 'object' is of type 'id' or
         'Class'.  */

      /* Check if at least it is of type 'id <Protocol>' or 'Class
         <Protocol>'; if so, look the property up in the
         protocols.  */
      if (TYPE_HAS_OBJC_INFO (TREE_TYPE (rtype)))
        {
          tree rprotos = TYPE_OBJC_PROTOCOL_LIST (TREE_TYPE (rtype));
          
          if (rprotos)
            {
              /* No point looking up declared @properties if we are
                 dealing with a class.  Classes have no declared
                 properties.  */
              if (!IS_CLASS (rtype))
                x = lookup_property_in_protocol_list (rprotos, property_ident);
              
              if (x == NULL_TREE)
                {
                  /* Ok, no property.  Maybe it was an
                     object.component dot-syntax without a declared
                     property (this is valid for classes too).  Look
                     for getter/setter methods and internally declare
                     an artifical property based on them if found.  */
                  x = maybe_make_artificial_property_decl (NULL_TREE,
                                                           NULL_TREE,
                                                           rprotos, 
                                                           property_ident,
                                                           IS_CLASS (rtype));
                }
            }
        }
      else if (objc_method_context)
        {
          /* Else, if we are inside a method it could be the case of
             'super' or 'self'.  */
          tree interface_type = NULL_TREE;
          tree t = object;
          while (TREE_CODE (t) == COMPOUND_EXPR
                 || TREE_CODE (t) == MODIFY_EXPR
                 || CONVERT_EXPR_P (t)
                 || TREE_CODE (t) == COMPONENT_REF)
            t = TREE_OPERAND (t, 0);
          
          if (t == UOBJC_SUPER_decl)
            {
              /* TODO: Check if this is correct also for 'super' in categories.  */
              interface_type = lookup_interface (CLASS_SUPER_NAME (implementation_template));
            }
          else if (t == self_decl)
            interface_type = lookup_interface (CLASS_NAME (implementation_template));

          if (interface_type)
            {
              if (TREE_CODE (objc_method_context) != CLASS_METHOD_DECL)
                x = lookup_property (interface_type, property_ident);
        
              if (x == NULL_TREE)
                {
                  /* Try the dot-syntax without a declared property.
                     If this is an access to 'self', it is possible
                     that they may refer to a setter/getter that is
                     not declared in the interface, but exists locally
                     in the implementation.  In that case, get the
                     implementation context and use it.  */
                  tree implementation = NULL_TREE;

                  if (t == self_decl)
                    implementation = objc_implementation_context;
                  
                  x = maybe_make_artificial_property_decl 
                    (interface_type, implementation, NULL_TREE,
                     property_ident,
                     (TREE_CODE (objc_method_context) == CLASS_METHOD_DECL));
                }
            }
        }
    }
  else
    {
      /* This is the case where we have more information on 'rtype'.  */
      tree basetype = TYPE_MAIN_VARIANT (rtype);

      /* Skip the pointer - if none, it's not an Objective-C object or
         class.  */
      if (basetype != NULL_TREE && TREE_CODE (basetype) == POINTER_TYPE)
        basetype = TREE_TYPE (basetype);
      else
        return NULL_TREE;

      /* Traverse typedefs.  */
      while (basetype != NULL_TREE
             && TREE_CODE (basetype) == RECORD_TYPE 
             && OBJC_TYPE_NAME (basetype)
             && TREE_CODE (OBJC_TYPE_NAME (basetype)) == TYPE_DECL
             && DECL_ORIGINAL_TYPE (OBJC_TYPE_NAME (basetype)))
        basetype = DECL_ORIGINAL_TYPE (OBJC_TYPE_NAME (basetype));

      if (basetype != NULL_TREE && TYPED_OBJECT (basetype))
        {
          tree interface_type = TYPE_OBJC_INTERFACE (basetype);
          tree protocol_list = TYPE_OBJC_PROTOCOL_LIST (basetype);

          if (interface_type 
              && (TREE_CODE (interface_type) == CLASS_INTERFACE_TYPE
                  || TREE_CODE (interface_type) == CATEGORY_INTERFACE_TYPE
                  || TREE_CODE (interface_type) == PROTOCOL_INTERFACE_TYPE))
            {
              /* Not sure 'rtype' could ever be a class here!  Just
                 for safety we keep the checks.  */
              if (!IS_CLASS (rtype))
                {
                  x = lookup_property (interface_type, property_ident);
                  
                  if (x == NULL_TREE)
                    x = lookup_property_in_protocol_list (protocol_list, 
                                                          property_ident);
                }
              
              if (x == NULL_TREE)
                {
                  /* Try the dot-syntax without a declared property.
                     If we are inside a method implementation, it is
                     possible that they may refer to a setter/getter
                     that is not declared in the interface, but exists
                     locally in the implementation.  In that case, get
                     the implementation context and use it.  */
                  tree implementation = NULL_TREE;

                  if (objc_implementation_context
                      && CLASS_NAME (objc_implementation_context) 
                      == OBJC_TYPE_NAME (interface_type))
                    implementation = objc_implementation_context;
                  
                  x = maybe_make_artificial_property_decl (interface_type,
                                                           implementation,
                                                           protocol_list, 
                                                           property_ident,
                                                           IS_CLASS (rtype));
                }
            }
        }
    }

  if (x)
    {
      tree expression;
      tree getter_call;

      /* We have an additional nasty problem here; if this
         PROPERTY_REF needs to become a 'getter', then the conversion
         from PROPERTY_REF into a getter call happens in gimplify,
         after the selector table has already been generated and when
         it is too late to add another selector to it.  To work around
         the problem, we always create the getter call at this stage,
         which puts the selector in the table.  Note that if the
         PROPERTY_REF becomes a 'setter' instead of a 'getter', then
         we have added a selector too many to the selector table.
         This is a little inefficient.

         Also note that method calls to 'self' and 'super' require the
         context (self_decl, UOBJS_SUPER_decl,
         objc_implementation_context etc) to be built correctly; this
         is yet another reason why building the call at the gimplify
         stage (when this context has been lost) is not very
         practical.  If we build it at this stage, we know it will
         always be built correctly.

         If the PROPERTY_HAS_NO_GETTER() (ie, it is an artificial
         property decl created to deal with a dotsyntax not really
         referring to an existing property) then do not try to build a
         call to the getter as there is no getter.  */
      if (PROPERTY_HAS_NO_GETTER (x))
        getter_call = NULL_TREE;
      else
        getter_call = objc_finish_message_expr (object,
                                                PROPERTY_GETTER_NAME (x),
                                                NULL_TREE);

      if (TREE_DEPRECATED (x))
        warn_deprecated_use (x, NULL_TREE);

      expression = build3 (PROPERTY_REF, TREE_TYPE(x), object, x, getter_call);
      SET_EXPR_LOCATION (expression, input_location);
      TREE_SIDE_EFFECTS (expression) = 1;
      
      return expression;
    }

  return NULL_TREE;
}

/* This hook routine is invoked by the parser when an expression such
   as 'xxx.yyy' is parsed, and 'xxx' is a class name.  This is the
   Objective-C 2.0 dot-syntax applied to classes, so we need to
   convert it into a setter/getter call on the class.  */
tree
objc_build_class_component_ref (tree class_name, tree property_ident)
{
  tree x = NULL_TREE;
  tree object, rtype;
  
  if (flag_objc1_only)
    error_at (input_location, "the dot syntax is not available in Objective-C 1.0");
  
  if (class_name == NULL_TREE || class_name == error_mark_node
      || TREE_CODE (class_name) != IDENTIFIER_NODE)
    return error_mark_node;
  
  if (property_ident == NULL_TREE || property_ident == error_mark_node
      || TREE_CODE (property_ident) != IDENTIFIER_NODE)
    return NULL_TREE;
  
  object = objc_get_class_reference (class_name);
  if (!object)
    {
      /* We know that 'class_name' is an Objective-C class name as the
         parser won't call this function if it is not.  This is only a
         double-check for safety.  */
      error_at (input_location, "could not find class %qE", class_name); 
      return error_mark_node;
    }

  rtype = lookup_interface (class_name);
  if (!rtype)
    {
      /* Again, this should never happen, but we do check.  */
      error_at (input_location, "could not find interface for class %qE", class_name); 
      return error_mark_node;
    }

  x = maybe_make_artificial_property_decl (rtype, NULL_TREE, NULL_TREE,
                                           property_ident,
                                           true);
  
  if (x)
    {
      tree expression;
      tree getter_call;

      if (PROPERTY_HAS_NO_GETTER (x))
        getter_call = NULL_TREE;
      else
        getter_call = objc_finish_message_expr (object,
                                                PROPERTY_GETTER_NAME (x),
                                                NULL_TREE);
      if (TREE_DEPRECATED (x))
        warn_deprecated_use (x, NULL_TREE);

      expression = build3 (PROPERTY_REF, TREE_TYPE(x), object, x, getter_call);
      SET_EXPR_LOCATION (expression, input_location);
      TREE_SIDE_EFFECTS (expression) = 1;

      return expression;
    }
  else
    {
      error_at (input_location, "could not find setter/getter for %qE in class %qE", 
                property_ident, class_name); 
      return error_mark_node;
    }

  return NULL_TREE;
}



/* This is used because we don't want to expose PROPERTY_REF to the
   C/C++ frontends.  Maybe we should!  */
bool
objc_is_property_ref (tree node)
{
  if (node  &&  TREE_CODE (node) == PROPERTY_REF)
    return true;
  else
    return false;
}

/* This hook routine is called when a MODIFY_EXPR is being built.  We
   check what is being modified; if it is a PROPERTY_REF, we need to
   generate a 'setter' function call for the property.  If this is not
   a PROPERTY_REF, we return NULL_TREE and the C/C++ frontend will go
   on creating their MODIFY_EXPR.

   This is used for example if you write

   object.count = 1;

   where 'count' is a property.  The left-hand side creates a
   PROPERTY_REF, and then the compiler tries to generate a MODIFY_EXPR
   to assign something to it.  We intercept that here, and generate a
   call to the 'setter' method instead.  */
tree
objc_maybe_build_modify_expr (tree lhs, tree rhs)
{
  if (lhs && TREE_CODE (lhs) == PROPERTY_REF)
    {
      tree object_expr = PROPERTY_REF_OBJECT (lhs);
      tree property_decl = PROPERTY_REF_PROPERTY_DECL (lhs);

      if (PROPERTY_READONLY (property_decl))
        {
          error ("readonly property can not be set");     
          return error_mark_node;
        }
      else
        {
          tree setter_argument = build_tree_list (NULL_TREE, rhs);
          tree setter;

          /* TODO: Check that the setter return type is 'void'.  */

          /* TODO: Decay argument in C.  */
          setter = objc_finish_message_expr (object_expr, 
                                             PROPERTY_SETTER_NAME (property_decl),
                                             setter_argument);
          return setter;
        }
    }
  else
    return NULL_TREE;
}

/* This hook is called by the frontend when one of the four unary
   expressions PREINCREMENT_EXPR, POSTINCREMENT_EXPR,
   PREDECREMENT_EXPR and POSTDECREMENT_EXPR is being built with an
   argument which is a PROPERTY_REF.  For example, this happens if you have

   object.count++;

   where 'count' is a property.  We need to use the 'getter' and
   'setter' for the property in an appropriate way to build the
   appropriate expression.  'code' is the code for the expression (one
   of the four mentioned above); 'argument' is the PROPERTY_REF, and
   'increment' is how much we need to add or subtract.  */   
tree
objc_build_incr_expr_for_property_ref (location_t location,
                                       enum tree_code code, 
                                       tree argument, tree increment)
{
  /* Here are the expressions that we want to build:

     For PREINCREMENT_EXPR / PREDECREMENT_EXPR:
    (temp = [object property] +/- increment, [object setProperty: temp], temp)
    
    For POSTINCREMENT_EXPR / POSTECREMENT_EXPR:
    (temp = [object property], [object setProperty: temp +/- increment], temp) */
  
  tree temp_variable_decl, bind;
  /* s1, s2 and s3 are the tree statements that we need in the
     compound expression.  */
  tree s1, s2, s3;
  
  /* Safety check.  */
  if (!argument || TREE_CODE (argument) != PROPERTY_REF)
    return error_mark_node;

  /* Declare __objc_property_temp in a local bind.  */
  temp_variable_decl = objc_create_temporary_var (TREE_TYPE (argument), "__objc_property_temp");
  DECL_SOURCE_LOCATION (temp_variable_decl) = location;
  bind = build3 (BIND_EXPR, void_type_node, temp_variable_decl, NULL, NULL);
  SET_EXPR_LOCATION (bind, location);
  TREE_SIDE_EFFECTS (bind) = 1;
  add_stmt (bind);
  
  /* Now build the compound statement.  */
  
  /* Note that the 'getter' is generated at gimplify time; at this
     time, we can simply put the property_ref (ie, argument) wherever
     we want the getter ultimately to be.  */
  
  /* s1: __objc_property_temp = [object property] <+/- increment> */
  switch (code)
    {
    case PREINCREMENT_EXPR:      
      /* __objc_property_temp = [object property] + increment */
      s1 = build2 (MODIFY_EXPR, void_type_node, temp_variable_decl,
                   build2 (PLUS_EXPR, TREE_TYPE (argument), argument, increment));
      break;
    case PREDECREMENT_EXPR:
      /* __objc_property_temp = [object property] - increment */
      s1 = build2 (MODIFY_EXPR, void_type_node, temp_variable_decl,
                   build2 (MINUS_EXPR, TREE_TYPE (argument), argument, increment));
      break;
    case POSTINCREMENT_EXPR:
    case POSTDECREMENT_EXPR:
      /* __objc_property_temp = [object property] */
      s1 = build2 (MODIFY_EXPR, void_type_node, temp_variable_decl, argument);
      break;
    default:
      gcc_unreachable ();
    }
  SET_EXPR_LOCATION (s1, location);
  
  /* s2: [object setProperty: __objc_property_temp <+/- increment>] */
  switch (code)
    {
    case PREINCREMENT_EXPR:      
    case PREDECREMENT_EXPR:
      /* [object setProperty: __objc_property_temp] */
      s2 = objc_maybe_build_modify_expr (argument, temp_variable_decl);
      break;
    case POSTINCREMENT_EXPR:
      /* [object setProperty: __objc_property_temp + increment] */
      s2 = objc_maybe_build_modify_expr (argument,
                                         build2 (PLUS_EXPR, TREE_TYPE (argument), 
                                                 temp_variable_decl, increment));
      break;
    case POSTDECREMENT_EXPR:
      /* [object setProperty: __objc_property_temp - increment] */
      s2 = objc_maybe_build_modify_expr (argument,
                                         build2 (MINUS_EXPR, TREE_TYPE (argument), 
                                                 temp_variable_decl, increment));
      break;
    default:
      gcc_unreachable ();
    }

  /* This happens if building the setter failed because the property
     is readonly.  */
  if (s2 == error_mark_node)
    return error_mark_node;

  SET_EXPR_LOCATION (s2, location); 
  
  /* s3: __objc_property_temp */
  s3 = build1 (NOP_EXPR, TREE_TYPE (argument), temp_variable_decl);
  SET_EXPR_LOCATION (s3, location); 
  
  /* Now build the compound statement (s1, s2, s3) */
  return build_compound_expr (location, build_compound_expr (location, s1, s2), s3);
}

tree
objc_build_method_signature (bool is_class_method, tree rettype, tree selector,
                             tree optparms, bool ellipsis)
{
  if (is_class_method)
    return build_method_decl (CLASS_METHOD_DECL, rettype, selector,
                              optparms, ellipsis);
  else
    return build_method_decl (INSTANCE_METHOD_DECL, rettype, selector,
                              optparms, ellipsis);
}

void
objc_add_method_declaration (bool is_class_method, tree decl, tree attributes)
{
  if (!objc_interface_context)
    {
      /* PS: At the moment, due to how the parser works, it should be
         impossible to get here.  But it's good to have the check in
         case the parser changes.
      */
      fatal_error ("method declaration not in @interface context");
    }

  if (flag_objc1_only && attributes)
    error_at (input_location, "method attributes are not available in Objective-C 1.0");

  objc_decl_method_attributes (&decl, attributes, 0);
  objc_add_method (objc_interface_context,
                   decl,
                   is_class_method,
                   objc_method_optional_flag);
}

/* Return 'true' if the method definition could be started, and
   'false' if not (because we are outside an @implementation context).
*/
bool
objc_start_method_definition (bool is_class_method, tree decl, tree attributes)
{
  if (!objc_implementation_context)
    {
      error ("method definition not in @implementation context");
      return false;
    }

  if (decl != NULL_TREE  && METHOD_SEL_NAME (decl) == error_mark_node)
    return false;

#ifndef OBJCPLUS
  /* Indicate no valid break/continue context by setting these variables
     to some non-null, non-label value.  We'll notice and emit the proper
     error message in c_finish_bc_stmt.  */
  c_break_label = c_cont_label = size_zero_node;
#endif

  if (attributes)
    warning_at (input_location, 0, "method attributes can not be specified in @implementation context");
  else
    objc_decl_method_attributes (&decl, attributes, 0);

  objc_add_method (objc_implementation_context,
                   decl,
                   is_class_method,
                   /* is optional */ false);
  start_method_def (decl);
  return true;
}

void
objc_add_instance_variable (tree decl)
{
  (void) add_instance_variable (objc_ivar_context,
                                objc_ivar_visibility,
                                decl);
}

/* Return true if TYPE is 'id'.  */

static bool
objc_is_object_id (tree type)
{
  return OBJC_TYPE_NAME (type) == objc_object_id;
}

static bool
objc_is_class_id (tree type)
{
  return OBJC_TYPE_NAME (type) == objc_class_id;
}

/* Construct a C struct with same name as KLASS, a base struct with tag
   SUPER_NAME (if any), and FIELDS indicated.  */

static tree
objc_build_struct (tree klass, tree fields, tree super_name)
{
  tree name = CLASS_NAME (klass);
  tree s = objc_start_struct (name);
  tree super = (super_name ? xref_tag (RECORD_TYPE, super_name) : NULL_TREE);
  tree t;
  VEC(tree,heap) *objc_info = NULL;
  int i;

  if (super)
    {
      /* Prepend a packed variant of the base class into the layout.  This
         is necessary to preserve ObjC ABI compatibility.  */
      tree base = build_decl (input_location,
                              FIELD_DECL, NULL_TREE, super);
      tree field = TYPE_FIELDS (super);

      while (field && DECL_CHAIN (field)
             && TREE_CODE (DECL_CHAIN (field)) == FIELD_DECL)
        field = DECL_CHAIN (field);

      /* For ObjC ABI purposes, the "packed" size of a base class is
         the sum of the offset and the size (in bits) of the last field
         in the class.  */
      DECL_SIZE (base)
        = (field && TREE_CODE (field) == FIELD_DECL
           ? size_binop (PLUS_EXPR,
                         size_binop (PLUS_EXPR,
                                     size_binop
                                     (MULT_EXPR,
                                      convert (bitsizetype,
                                               DECL_FIELD_OFFSET (field)),
                                      bitsize_int (BITS_PER_UNIT)),
                                     DECL_FIELD_BIT_OFFSET (field)),
                         DECL_SIZE (field))
           : bitsize_zero_node);
      DECL_SIZE_UNIT (base)
        = size_binop (FLOOR_DIV_EXPR, convert (sizetype, DECL_SIZE (base)),
                      size_int (BITS_PER_UNIT));
      DECL_ARTIFICIAL (base) = 1;
      DECL_ALIGN (base) = 1;
      DECL_FIELD_CONTEXT (base) = s;
#ifdef OBJCPLUS
      DECL_FIELD_IS_BASE (base) = 1;

      if (fields)
        TREE_NO_WARNING (fields) = 1;   /* Suppress C++ ABI warnings -- we   */
#endif                                  /* are following the ObjC ABI here.  */
      DECL_CHAIN (base) = fields;
      fields = base;
    }

  /* NB: Calling finish_struct() may cause type TYPE_LANG_SPECIFIC fields
     in all variants of this RECORD_TYPE to be clobbered, but it is therein
     that we store protocol conformance info (e.g., 'NSObject <MyProtocol>').
     Hence, we must squirrel away the ObjC-specific information before calling
     finish_struct(), and then reinstate it afterwards.  */

  for (t = TYPE_NEXT_VARIANT (s); t; t = TYPE_NEXT_VARIANT (t))
    {
      if (!TYPE_HAS_OBJC_INFO (t))
        {
          INIT_TYPE_OBJC_INFO (t);
          TYPE_OBJC_INTERFACE (t) = klass;
        }
      VEC_safe_push (tree, heap, objc_info, TYPE_OBJC_INFO (t));
    }

  /* Point the struct at its related Objective-C class.  */
  INIT_TYPE_OBJC_INFO (s);
  TYPE_OBJC_INTERFACE (s) = klass;

  s = objc_finish_struct (s, fields);

  for (i = 0, t = TYPE_NEXT_VARIANT (s); t; t = TYPE_NEXT_VARIANT (t), i++)
    {
      TYPE_OBJC_INFO (t) = VEC_index (tree, objc_info, i);
      /* Replace the IDENTIFIER_NODE with an actual @interface.  */
      TYPE_OBJC_INTERFACE (t) = klass;
    }
  VEC_free (tree, heap, objc_info);

  /* Use TYPE_BINFO structures to point at the super class, if any.  */
  objc_xref_basetypes (s, super);

  /* Mark this struct as a class template.  */
  CLASS_STATIC_TEMPLATE (klass) = s;

  return s;
}

/* Build a type differing from TYPE only in that TYPE_VOLATILE is set.
   Unlike tree.c:build_qualified_type(), preserve TYPE_LANG_SPECIFIC in the
   process.  */
static tree
objc_build_volatilized_type (tree type)
{
  tree t;

  /* Check if we have not constructed the desired variant already.  */
  for (t = TYPE_MAIN_VARIANT (type); t; t = TYPE_NEXT_VARIANT (t))
    {
      /* The type qualifiers must (obviously) match up.  */
      if (!TYPE_VOLATILE (t)
          || (TYPE_READONLY (t) != TYPE_READONLY (type))
          || (TYPE_RESTRICT (t) != TYPE_RESTRICT (type)))
        continue;

      /* For pointer types, the pointees (and hence their TYPE_LANG_SPECIFIC
         info, if any) must match up.  */
      if (POINTER_TYPE_P (t)
          && (TREE_TYPE (t) != TREE_TYPE (type)))
        continue;

      /* Only match up the types which were previously volatilized in similar fashion and not
         because they were declared as such. */
      if (!lookup_attribute ("objc_volatilized", TYPE_ATTRIBUTES (t)))
        continue;

      /* Everything matches up!  */
      return t;
    }

  /* Ok, we could not re-use any of the pre-existing variants.  Create
     a new one.  */
  t = build_variant_type_copy (type);
  TYPE_VOLATILE (t) = 1;

  TYPE_ATTRIBUTES (t) = merge_attributes (TYPE_ATTRIBUTES (type),
                                          tree_cons (get_identifier ("objc_volatilized"),
                                          NULL_TREE,
                                          NULL_TREE));
  if (TREE_CODE (t) == ARRAY_TYPE)
    TREE_TYPE (t) = objc_build_volatilized_type (TREE_TYPE (t));

  /* Set up the canonical type information. */
  if (TYPE_STRUCTURAL_EQUALITY_P (type))
    SET_TYPE_STRUCTURAL_EQUALITY (t);
  else if (TYPE_CANONICAL (type) != type)
    TYPE_CANONICAL (t) = objc_build_volatilized_type (TYPE_CANONICAL (type));
  else
    TYPE_CANONICAL (t) = t;

  return t;
}

/* Mark DECL as being 'volatile' for purposes of Darwin
   _setjmp()/_longjmp() exception handling.  Called from
   objc_mark_locals_volatile().  */
void
objc_volatilize_decl (tree decl)
{
  /* Do not mess with variables that are 'static' or (already)
     'volatile'.  */
  if (!TREE_THIS_VOLATILE (decl) && !TREE_STATIC (decl)
      && (TREE_CODE (decl) == VAR_DECL
          || TREE_CODE (decl) == PARM_DECL))
    {
      tree t = TREE_TYPE (decl);

      t = objc_build_volatilized_type (t);

      TREE_TYPE (decl) = t;
      TREE_THIS_VOLATILE (decl) = 1;
      TREE_SIDE_EFFECTS (decl) = 1;
      DECL_REGISTER (decl) = 0;
#ifndef OBJCPLUS
      C_DECL_REGISTER (decl) = 0;
#endif
    }
}

/* Check if protocol PROTO is adopted (directly or indirectly) by class CLS
   (including its categories and superclasses) or by object type TYP.
   Issue a warning if PROTO is not adopted anywhere and WARN is set.  */

static bool
objc_lookup_protocol (tree proto, tree cls, tree typ, bool warn)
{
  bool class_type = (cls != NULL_TREE);

  while (cls)
    {
      tree c;

      /* Check protocols adopted by the class and its categories.  */
      for (c = cls; c; c = CLASS_CATEGORY_LIST (c))
        {
          if (lookup_protocol_in_reflist (CLASS_PROTOCOL_LIST (c), proto))
            return true;
        }

      /* Repeat for superclasses.  */
      cls = lookup_interface (CLASS_SUPER_NAME (cls));
    }

  /* Check for any protocols attached directly to the object type.  */
  if (TYPE_HAS_OBJC_INFO (typ))
    {
      if (lookup_protocol_in_reflist (TYPE_OBJC_PROTOCOL_LIST (typ), proto))
        return true;
    }

  if (warn)
    {
      *errbuf = 0;
      gen_type_name_0 (class_type ? typ : TYPE_POINTER_TO (typ));
      /* NB: Types 'id' and 'Class' cannot reasonably be described as
         "implementing" a given protocol, since they do not have an
         implementation.  */
      if (class_type)
        warning (0, "class %qs does not implement the %qE protocol",
                 identifier_to_locale (errbuf), PROTOCOL_NAME (proto));
      else
        warning (0, "type %qs does not conform to the %qE protocol",
                 identifier_to_locale (errbuf), PROTOCOL_NAME (proto));
    }

  return false;
}

/* Check if class RCLS and instance struct type RTYP conform to at least the
   same protocols that LCLS and LTYP conform to.  */

static bool
objc_compare_protocols (tree lcls, tree ltyp, tree rcls, tree rtyp, bool warn)
{
  tree p;
  bool have_lproto = false;

  while (lcls)
    {
      /* NB: We do _not_ look at categories defined for LCLS; these may or
         may not get loaded in, and therefore it is unreasonable to require
         that RCLS/RTYP must implement any of their protocols.  */
      for (p = CLASS_PROTOCOL_LIST (lcls); p; p = TREE_CHAIN (p))
        {
          have_lproto = true;

          if (!objc_lookup_protocol (TREE_VALUE (p), rcls, rtyp, warn))
            return warn;
        }

      /* Repeat for superclasses.  */
      lcls = lookup_interface (CLASS_SUPER_NAME (lcls));
    }

  /* Check for any protocols attached directly to the object type.  */
  if (TYPE_HAS_OBJC_INFO (ltyp))
    {
      for (p = TYPE_OBJC_PROTOCOL_LIST (ltyp); p; p = TREE_CHAIN (p))
        {
          have_lproto = true;

          if (!objc_lookup_protocol (TREE_VALUE (p), rcls, rtyp, warn))
            return warn;
        }
    }

  /* NB: If LTYP and LCLS have no protocols to search for, return 'true'
     vacuously, _unless_ RTYP is a protocol-qualified 'id'.  We can get
     away with simply checking for 'id' or 'Class' (!RCLS), since this
     routine will not get called in other cases.  */
  return have_lproto || (rcls != NULL_TREE);
}

/* Given two types TYPE1 and TYPE2, return their least common ancestor.
   Both TYPE1 and TYPE2 must be pointers, and already determined to be
   compatible by objc_compare_types() below.  */

tree
objc_common_type (tree type1, tree type2)
{
  tree inner1 = TREE_TYPE (type1), inner2 = TREE_TYPE (type2);

  while (POINTER_TYPE_P (inner1))
    {
      inner1 = TREE_TYPE (inner1);
      inner2 = TREE_TYPE (inner2);
    }

  /* If one type is derived from another, return the base type.  */
  if (DERIVED_FROM_P (inner1, inner2))
    return type1;
  else if (DERIVED_FROM_P (inner2, inner1))
    return type2;

  /* If both types are 'Class', return 'Class'.  */
  if (objc_is_class_id (inner1) && objc_is_class_id (inner2))
    return objc_class_type;

  /* Otherwise, return 'id'.  */
  return objc_object_type;
}

/* Determine if it is permissible to assign (if ARGNO is greater than -3)
   an instance of RTYP to an instance of LTYP or to compare the two
   (if ARGNO is equal to -3), per ObjC type system rules.  Before
   returning 'true', this routine may issue warnings related to, e.g.,
   protocol conformance.  When returning 'false', the routine must
   produce absolutely no warnings; the C or C++ front-end will do so
   instead, if needed.  If either LTYP or RTYP is not an Objective-C
   type, the routine must return 'false'.

   The ARGNO parameter is encoded as follows:
     >= 1       Parameter number (CALLEE contains function being called);
     0          Return value;
     -1         Assignment;
     -2         Initialization;
     -3         Comparison (LTYP and RTYP may match in either direction);
     -4         Silent comparison (for C++ overload resolution);
     -5         Silent "specialization" comparison for RTYP to be a "specialization" 
                of LTYP (a specialization means that RTYP is LTYP plus some constraints, 
                so that each object of type RTYP is also of type LTYP).  This is used
                when comparing property types.  */

bool
objc_compare_types (tree ltyp, tree rtyp, int argno, tree callee)
{
  tree lcls, rcls, lproto, rproto;
  bool pointers_compatible;

  /* We must be dealing with pointer types */
  if (!POINTER_TYPE_P (ltyp) || !POINTER_TYPE_P (rtyp))
    return false;

  do
    {
      ltyp = TREE_TYPE (ltyp);  /* Remove indirections.  */
      rtyp = TREE_TYPE (rtyp);
    }
  while (POINTER_TYPE_P (ltyp) && POINTER_TYPE_P (rtyp));

  /* We must also handle function pointers, since ObjC is a bit more
     lenient than C or C++ on this.  */
  if (TREE_CODE (ltyp) == FUNCTION_TYPE && TREE_CODE (rtyp) == FUNCTION_TYPE)
    {
      /* Return types must be covariant.  */
      if (!comptypes (TREE_TYPE (ltyp), TREE_TYPE (rtyp))
          && !objc_compare_types (TREE_TYPE (ltyp), TREE_TYPE (rtyp),
                                  argno, callee))
      return false;

      /* Argument types must be contravariant.  */
      for (ltyp = TYPE_ARG_TYPES (ltyp), rtyp = TYPE_ARG_TYPES (rtyp);
           ltyp && rtyp; ltyp = TREE_CHAIN (ltyp), rtyp = TREE_CHAIN (rtyp))
        {
          if (!comptypes (TREE_VALUE (rtyp), TREE_VALUE (ltyp))
              && !objc_compare_types (TREE_VALUE (rtyp), TREE_VALUE (ltyp),
                                      argno, callee))
            return false;
      }

      return (ltyp == rtyp);
    }

  /* Past this point, we are only interested in ObjC class instances,
     or 'id' or 'Class'.  */
  if (TREE_CODE (ltyp) != RECORD_TYPE || TREE_CODE (rtyp) != RECORD_TYPE)
    return false;

  if (!objc_is_object_id (ltyp) && !objc_is_class_id (ltyp)
      && !TYPE_HAS_OBJC_INFO (ltyp))
    return false;

  if (!objc_is_object_id (rtyp) && !objc_is_class_id (rtyp)
      && !TYPE_HAS_OBJC_INFO (rtyp))
    return false;

  /* Past this point, we are committed to returning 'true' to the caller
     (unless performing a silent comparison; see below).  However, we can
     still warn about type and/or protocol mismatches.  */

  if (TYPE_HAS_OBJC_INFO (ltyp))
    {
      lcls = TYPE_OBJC_INTERFACE (ltyp);
      lproto = TYPE_OBJC_PROTOCOL_LIST (ltyp);
    }
  else
    lcls = lproto = NULL_TREE;

  if (TYPE_HAS_OBJC_INFO (rtyp))
    {
      rcls = TYPE_OBJC_INTERFACE (rtyp);
      rproto = TYPE_OBJC_PROTOCOL_LIST (rtyp);
    }
  else
    rcls = rproto = NULL_TREE;

  /* If we could not find an @interface declaration, we must have
     only seen a @class declaration; for purposes of type comparison,
     treat it as a stand-alone (root) class.  */

  if (lcls && TREE_CODE (lcls) == IDENTIFIER_NODE)
    lcls = NULL_TREE;

  if (rcls && TREE_CODE (rcls) == IDENTIFIER_NODE)
    rcls = NULL_TREE;

  /* If either type is an unqualified 'id', we're done.  This is because
     an 'id' can be assigned to or from any type with no warnings.  */
  if (argno != -5)
    {
      if ((!lproto && objc_is_object_id (ltyp))
          || (!rproto && objc_is_object_id (rtyp)))
        return true;
    }
  else
    {
      /* For property checks, though, an 'id' is considered the most
         general type of object, hence if you try to specialize an
         'NSArray *' (ltyp) property with an 'id' (rtyp) one, we need
         to warn.  */
      if (!lproto && objc_is_object_id (ltyp))
        return true;
    }
  
  pointers_compatible = (TYPE_MAIN_VARIANT (ltyp) == TYPE_MAIN_VARIANT (rtyp));

  /* If the underlying types are the same, and at most one of them has
     a protocol list, we do not need to issue any diagnostics.  */
  if (pointers_compatible && (!lproto || !rproto))
    return true;

  /* If exactly one of the types is 'Class', issue a diagnostic; any
     exceptions of this rule have already been handled.  */
  if (objc_is_class_id (ltyp) ^ objc_is_class_id (rtyp))
    pointers_compatible = false;
  /* Otherwise, check for inheritance relations.  */
  else
    {
      if (!pointers_compatible)
        {
          /* Again, if any of the two is an 'id', we're satisfied,
             unless we're comparing properties, in which case only an
             'id' on the left-hand side (old property) is good
             enough.  */
          if (argno != -5)
            pointers_compatible
              = (objc_is_object_id (ltyp) || objc_is_object_id (rtyp));
          else
            pointers_compatible = objc_is_object_id (ltyp);         
        }

      if (!pointers_compatible)
        pointers_compatible = DERIVED_FROM_P (ltyp, rtyp);

      if (!pointers_compatible && (argno == -3 || argno == -4))
        pointers_compatible = DERIVED_FROM_P (rtyp, ltyp);
    }

  /* If the pointers match modulo protocols, check for protocol conformance
     mismatches.  */
  if (pointers_compatible)
    {
      pointers_compatible = objc_compare_protocols (lcls, ltyp, rcls, rtyp,
                                                    argno != -3);

      if (!pointers_compatible && argno == -3)
        pointers_compatible = objc_compare_protocols (rcls, rtyp, lcls, ltyp,
                                                      argno != -3);
    }

  if (!pointers_compatible)
    {
      /* The two pointers are not exactly compatible.  Issue a warning, unless
         we are performing a silent comparison, in which case return 'false'
         instead.  */
      /* NB: For the time being, we shall make our warnings look like their
         C counterparts.  In the future, we may wish to make them more
         ObjC-specific.  */
      switch (argno)
        {
        case -5:
        case -4:
          return false;

        case -3:
          warning (0, "comparison of distinct Objective-C types lacks a cast");
          break;

        case -2:
          warning (0, "initialization from distinct Objective-C type");
          break;

        case -1:
          warning (0, "assignment from distinct Objective-C type");
          break;

        case 0:
          warning (0, "distinct Objective-C type in return");
          break;

        default:
          warning (0, "passing argument %d of %qE from distinct "
                   "Objective-C type", argno, callee);
          break;
        }
    }

  return true;
}

/* This routine is similar to objc_compare_types except that function-pointers are
   excluded. This is because, caller assumes that common types are of (id, Object*)
   variety and calls objc_common_type to obtain a common type. There is no commonolty
   between two function-pointers in this regard. */

bool 
objc_have_common_type (tree ltyp, tree rtyp, int argno, tree callee)
{
  if (objc_compare_types (ltyp, rtyp, argno, callee))
    {
      /* exclude function-pointer types. */
      do
        {
          ltyp = TREE_TYPE (ltyp);  /* Remove indirections.  */
          rtyp = TREE_TYPE (rtyp);
        }
      while (POINTER_TYPE_P (ltyp) && POINTER_TYPE_P (rtyp));
      return !(TREE_CODE (ltyp) == FUNCTION_TYPE && TREE_CODE (rtyp) == FUNCTION_TYPE);
    }
  return false;
}

/* Check if LTYP and RTYP have the same type qualifiers.  If either type
   lives in the volatilized hash table, ignore the 'volatile' bit when
   making the comparison.  */

bool
objc_type_quals_match (tree ltyp, tree rtyp)
{
  int lquals = TYPE_QUALS (ltyp), rquals = TYPE_QUALS (rtyp);

  if (lookup_attribute ("objc_volatilized", TYPE_ATTRIBUTES (ltyp)))
    lquals &= ~TYPE_QUAL_VOLATILE;

  if (lookup_attribute ("objc_volatilized", TYPE_ATTRIBUTES (rtyp)))
    rquals &= ~TYPE_QUAL_VOLATILE;

  return (lquals == rquals);
}

#ifndef OBJCPLUS
/* Determine if CHILD is derived from PARENT.  The routine assumes that
   both parameters are RECORD_TYPEs, and is non-reflexive.  */

static bool
objc_derived_from_p (tree parent, tree child)
{
  parent = TYPE_MAIN_VARIANT (parent);

  for (child = TYPE_MAIN_VARIANT (child);
       TYPE_BINFO (child) && BINFO_N_BASE_BINFOS (TYPE_BINFO (child));)
    {
      child = TYPE_MAIN_VARIANT (BINFO_TYPE (BINFO_BASE_BINFO
                                             (TYPE_BINFO (child),
                                              0)));

      if (child == parent)
        return true;
    }

  return false;
}
#endif

static tree
objc_build_component_ref (tree datum, tree component)
{
  /* If COMPONENT is NULL, the caller is referring to the anonymous
     base class field.  */
  if (!component)
    {
      tree base = TYPE_FIELDS (TREE_TYPE (datum));

      return build3 (COMPONENT_REF, TREE_TYPE (base), datum, base, NULL_TREE);
    }

  /* The 'build_component_ref' routine has been removed from the C++
     front-end, but 'finish_class_member_access_expr' seems to be
     a worthy substitute.  */
#ifdef OBJCPLUS
  return finish_class_member_access_expr (datum, component, false,
                                          tf_warning_or_error);
#else
  return build_component_ref (input_location, datum, component);
#endif
}

/* Recursively copy inheritance information rooted at BINFO.  To do this,
   we emulate the song and dance performed by cp/tree.c:copy_binfo().  */

static tree
objc_copy_binfo (tree binfo)
{
  tree btype = BINFO_TYPE (binfo);
  tree binfo2 = make_tree_binfo (BINFO_N_BASE_BINFOS (binfo));
  tree base_binfo;
  int ix;

  BINFO_TYPE (binfo2) = btype;
  BINFO_OFFSET (binfo2) = BINFO_OFFSET (binfo);
  BINFO_BASE_ACCESSES (binfo2) = BINFO_BASE_ACCESSES (binfo);

  /* Recursively copy base binfos of BINFO.  */
  for (ix = 0; BINFO_BASE_ITERATE (binfo, ix, base_binfo); ix++)
    {
      tree base_binfo2 = objc_copy_binfo (base_binfo);

      BINFO_INHERITANCE_CHAIN (base_binfo2) = binfo2;
      BINFO_BASE_APPEND (binfo2, base_binfo2);
    }

  return binfo2;
}

/* Record superclass information provided in BASETYPE for ObjC class REF.
   This is loosely based on cp/decl.c:xref_basetypes().  */

static void
objc_xref_basetypes (tree ref, tree basetype)
{
  tree binfo = make_tree_binfo (basetype ? 1 : 0);

  TYPE_BINFO (ref) = binfo;
  BINFO_OFFSET (binfo) = size_zero_node;
  BINFO_TYPE (binfo) = ref;

  if (basetype)
    {
      tree base_binfo = objc_copy_binfo (TYPE_BINFO (basetype));

      BINFO_INHERITANCE_CHAIN (base_binfo) = binfo;
      BINFO_BASE_ACCESSES (binfo) = VEC_alloc (tree, gc, 1);
      BINFO_BASE_APPEND (binfo, base_binfo);
      BINFO_BASE_ACCESS_APPEND (binfo, access_public_node);
    }
}

/* Called from finish_decl.  */

void
objc_check_decl (tree decl)
{
  tree type = TREE_TYPE (decl);

  if (TREE_CODE (type) != RECORD_TYPE)
    return;
  if (OBJC_TYPE_NAME (type) && (type = objc_is_class_name (OBJC_TYPE_NAME (type))))
    error ("statically allocated instance of Objective-C class %qE",
           type);
}

void
objc_check_global_decl (tree decl)
{
  tree id = DECL_NAME (decl);
  if (objc_is_class_name (id) && global_bindings_p())
    error ("redeclaration of Objective-C class %qs", IDENTIFIER_POINTER (id));
}

/* Return a non-volatalized version of TYPE. */

tree
objc_non_volatilized_type (tree type)
{
  if (lookup_attribute ("objc_volatilized", TYPE_ATTRIBUTES (type)))
    type = build_qualified_type (type, (TYPE_QUALS (type) & ~TYPE_QUAL_VOLATILE));
  return type;
}

/* Construct a PROTOCOLS-qualified variant of INTERFACE, where INTERFACE may
   either name an Objective-C class, or refer to the special 'id' or 'Class'
   types.  If INTERFACE is not a valid ObjC type, just return it unchanged.  */

tree
objc_get_protocol_qualified_type (tree interface, tree protocols)
{
  /* If INTERFACE is not provided, default to 'id'.  */
  tree type = (interface ? objc_is_id (interface) : objc_object_type);
  bool is_ptr = (type != NULL_TREE);

  if (!is_ptr)
    {
      type = objc_is_class_name (interface);

      if (type)
        {
          /* If looking at a typedef, retrieve the precise type it
             describes.  */
          if (TREE_CODE (interface) == IDENTIFIER_NODE)
            interface = identifier_global_value (interface);

          type = ((interface && TREE_CODE (interface) == TYPE_DECL
                   && DECL_ORIGINAL_TYPE (interface))
                  ? DECL_ORIGINAL_TYPE (interface)
                  : xref_tag (RECORD_TYPE, type));
        }
      else
        {
          /* This case happens when we are given an 'interface' which
             is not a valid class name.  For example if a typedef was
             used, and 'interface' really is the identifier of the
             typedef, but when you resolve it you don't get an
             Objective-C class, but something else, such as 'int'.
             This is an error; protocols make no sense unless you use
             them with Objective-C objects.  */
          error_at (input_location, "only Objective-C object types can be qualified with a protocol");

          /* Try to recover.  Ignore the invalid class name, and treat
             the object as an 'id' to silence further warnings about
             the class.  */
          type = objc_object_type;
          is_ptr = true;
        }
    }

  if (protocols)
    {
      type = build_variant_type_copy (type);

      /* For pointers (i.e., 'id' or 'Class'), attach the protocol(s)
         to the pointee.  */
      if (is_ptr)
        {
          tree orig_pointee_type = TREE_TYPE (type);
          TREE_TYPE (type) = build_variant_type_copy (orig_pointee_type);

          /* Set up the canonical type information. */
          TYPE_CANONICAL (type) 
            = TYPE_CANONICAL (TYPE_POINTER_TO (orig_pointee_type));

          TYPE_POINTER_TO (TREE_TYPE (type)) = type;
          type = TREE_TYPE (type);
        }

      /* Look up protocols and install in lang specific list.  */
      DUP_TYPE_OBJC_INFO (type, TYPE_MAIN_VARIANT (type));
      TYPE_OBJC_PROTOCOL_LIST (type) = lookup_and_install_protocols (protocols);

      /* For RECORD_TYPEs, point to the @interface; for 'id' and 'Class',
         return the pointer to the new pointee variant.  */
      if (is_ptr)
        type = TYPE_POINTER_TO (type);
      else
        TYPE_OBJC_INTERFACE (type)
          = TYPE_OBJC_INTERFACE (TYPE_MAIN_VARIANT (type));
    }

  return type;
}

/* Check for circular dependencies in protocols.  The arguments are
   PROTO, the protocol to check, and LIST, a list of protocol it
   conforms to.  */

static void
check_protocol_recursively (tree proto, tree list)
{
  tree p;

  for (p = list; p; p = TREE_CHAIN (p))
    {
      tree pp = TREE_VALUE (p);

      if (TREE_CODE (pp) == IDENTIFIER_NODE)
        pp = lookup_protocol (pp);

      if (pp == proto)
        fatal_error ("protocol %qE has circular dependency",
                     PROTOCOL_NAME (pp));
      if (pp)
        check_protocol_recursively (proto, PROTOCOL_LIST (pp));
    }
}

/* Look up PROTOCOLS, and return a list of those that are found.
   If none are found, return NULL.  */

static tree
lookup_and_install_protocols (tree protocols)
{
  tree proto;
  tree return_value = NULL_TREE;

  if (protocols == error_mark_node)
    return NULL;

  for (proto = protocols; proto; proto = TREE_CHAIN (proto))
    {
      tree ident = TREE_VALUE (proto);
      tree p = lookup_protocol (ident);

      if (p)
        return_value = chainon (return_value,
                                build_tree_list (NULL_TREE, p));
      else if (ident != error_mark_node)
        error ("cannot find protocol declaration for %qE",
               ident);
    }

  return return_value;
}

/* Create a declaration for field NAME of a given TYPE.  */

static tree
create_field_decl (tree type, const char *name)
{
  return build_decl (input_location,
                     FIELD_DECL, get_identifier (name), type);
}

/* Create a global, static declaration for variable NAME of a given TYPE.  The
   finish_var_decl() routine will need to be called on it afterwards.  */

static tree
start_var_decl (tree type, const char *name)
{
  tree var = build_decl (input_location,
                         VAR_DECL, get_identifier (name), type);

  TREE_STATIC (var) = 1;
  DECL_INITIAL (var) = error_mark_node;  /* A real initializer is coming... */
  DECL_IGNORED_P (var) = 1;
  DECL_ARTIFICIAL (var) = 1;
  DECL_CONTEXT (var) = NULL_TREE;
#ifdef OBJCPLUS
  DECL_THIS_STATIC (var) = 1; /* squash redeclaration errors */
#endif

  return var;
}

/* Finish off the variable declaration created by start_var_decl().  */

static void
finish_var_decl (tree var, tree initializer)
{
  finish_decl (var, input_location, initializer, NULL_TREE, NULL_TREE);
}

/* Find the decl for the constant string class reference.  This is only
   used for the NeXT runtime.  */

static tree
setup_string_decl (void)
{
  char *name;
  size_t length;

  /* %s in format will provide room for terminating null */
  length = strlen (STRING_OBJECT_GLOBAL_FORMAT)
           + strlen (constant_string_class_name);
  name = XNEWVEC (char, length);
  sprintf (name, STRING_OBJECT_GLOBAL_FORMAT,
           constant_string_class_name);
  constant_string_global_id = get_identifier (name);
  string_class_decl = lookup_name (constant_string_global_id);

  return string_class_decl;
}

/* Purpose: "play" parser, creating/installing representations
   of the declarations that are required by Objective-C.

   Model:

        type_spec--------->sc_spec
        (tree_list)        (tree_list)
            |                  |
            |                  |
        identifier_node    identifier_node  */

static void
synth_module_prologue (void)
{
  tree type;
  enum debug_info_type save_write_symbols = write_symbols;
  const struct gcc_debug_hooks *const save_hooks = debug_hooks;

  /* Suppress outputting debug symbols, because
     dbxout_init hasn't been called yet.  */
  write_symbols = NO_DEBUG;
  debug_hooks = &do_nothing_debug_hooks;

#ifdef OBJCPLUS
  push_lang_context (lang_name_c); /* extern "C" */
#endif

  /* The following are also defined in <objc/objc.h> and friends.  */

  objc_object_id = get_identifier (TAG_OBJECT);
  objc_class_id = get_identifier (TAG_CLASS);

  objc_object_reference = xref_tag (RECORD_TYPE, objc_object_id);
  objc_class_reference = xref_tag (RECORD_TYPE, objc_class_id);

  objc_object_type = build_pointer_type (objc_object_reference);
  objc_class_type = build_pointer_type (objc_class_reference);

  objc_object_name = get_identifier (OBJECT_TYPEDEF_NAME);
  objc_class_name = get_identifier (CLASS_TYPEDEF_NAME);

  /* Declare the 'id' and 'Class' typedefs.  */

  type = lang_hooks.decls.pushdecl (build_decl (input_location,
                                                TYPE_DECL,
                                                objc_object_name,
                                                objc_object_type));
  TREE_NO_WARNING (type) = 1;
  type = lang_hooks.decls.pushdecl (build_decl (input_location,
                                                TYPE_DECL,
                                                objc_class_name,
                                                objc_class_type));
  TREE_NO_WARNING (type) = 1;

  /* Forward-declare '@interface Protocol'.  */

  type = get_identifier (PROTOCOL_OBJECT_CLASS_NAME);
  objc_declare_class (tree_cons (NULL_TREE, type, NULL_TREE));
  objc_protocol_type = build_pointer_type (xref_tag (RECORD_TYPE,
                                type));

  /* Declare type of selector-objects that represent an operation name.  */

  if (flag_next_runtime)
    /* `struct objc_selector *' */
    objc_selector_type
      = build_pointer_type (xref_tag (RECORD_TYPE,
                                      get_identifier (TAG_SELECTOR)));
  else
    /* `const struct objc_selector *' */
    objc_selector_type
      = build_pointer_type
        (build_qualified_type (xref_tag (RECORD_TYPE,
                                         get_identifier (TAG_SELECTOR)),
                               TYPE_QUAL_CONST));

  /* Declare receiver type used for dispatching messages to 'super'.  */

  /* `struct objc_super *' */
  objc_super_type = build_pointer_type (xref_tag (RECORD_TYPE,
                                                  get_identifier (TAG_SUPER)));

  /* Declare pointers to method and ivar lists.  */
  objc_method_list_ptr = build_pointer_type
                         (xref_tag (RECORD_TYPE,
                                    get_identifier (UTAG_METHOD_LIST)));
  objc_method_proto_list_ptr
    = build_pointer_type (xref_tag (RECORD_TYPE,
                                    get_identifier (UTAG_METHOD_PROTOTYPE_LIST)));
  objc_ivar_list_ptr = build_pointer_type
                       (xref_tag (RECORD_TYPE,
                                  get_identifier (UTAG_IVAR_LIST)));

  /* TREE_NOTHROW is cleared for the message-sending functions,
     because the function that gets called can throw in Obj-C++, or
     could itself call something that can throw even in Obj-C.  */

  if (flag_next_runtime)
    {
      /* NB: In order to call one of the ..._stret (struct-returning)
      functions, the function *MUST* first be cast to a signature that
      corresponds to the actual ObjC method being invoked.  This is
      what is done by the build_objc_method_call() routine below.  */

      /* id objc_msgSend (id, SEL, ...); */
      /* id objc_msgSendNonNil (id, SEL, ...); */
      /* id objc_msgSend_stret (id, SEL, ...); */
      /* id objc_msgSendNonNil_stret (id, SEL, ...); */
      type
        = build_varargs_function_type_list (objc_object_type,
                                            objc_object_type,
                                            objc_selector_type,
                                            NULL_TREE);
      umsg_decl = add_builtin_function (TAG_MSGSEND,
                                        type, 0, NOT_BUILT_IN,
                                        NULL, NULL_TREE);
      umsg_nonnil_decl = add_builtin_function (TAG_MSGSEND_NONNIL,
                                               type, 0, NOT_BUILT_IN,
                                               NULL, NULL_TREE);
      umsg_stret_decl = add_builtin_function (TAG_MSGSEND_STRET,
                                              type, 0, NOT_BUILT_IN,
                                              NULL, NULL_TREE);
      umsg_nonnil_stret_decl = add_builtin_function (TAG_MSGSEND_NONNIL_STRET,
                                                     type, 0, NOT_BUILT_IN,
                                                     NULL, NULL_TREE);

      /* These can throw, because the function that gets called can throw
         in Obj-C++, or could itself call something that can throw even
         in Obj-C.  */
      TREE_NOTHROW (umsg_decl) = 0;
      TREE_NOTHROW (umsg_nonnil_decl) = 0;
      TREE_NOTHROW (umsg_stret_decl) = 0;
      TREE_NOTHROW (umsg_nonnil_stret_decl) = 0;

      /* id objc_msgSend_Fast (id, SEL, ...)
           __attribute__ ((hard_coded_address (OFFS_MSGSEND_FAST))); */
#ifdef OFFS_MSGSEND_FAST
      umsg_fast_decl = add_builtin_function (TAG_MSGSEND_FAST,
                                             type, 0, NOT_BUILT_IN,
                                             NULL, NULL_TREE);
      TREE_NOTHROW (umsg_fast_decl) = 0;
      DECL_ATTRIBUTES (umsg_fast_decl)
        = tree_cons (get_identifier ("hard_coded_address"),
                     build_int_cst (NULL_TREE, OFFS_MSGSEND_FAST),
                     NULL_TREE);
#else
      /* No direct dispatch available.  */
      umsg_fast_decl = umsg_decl;
#endif

      /* id objc_msgSendSuper (struct objc_super *, SEL, ...); */
      /* id objc_msgSendSuper_stret (struct objc_super *, SEL, ...); */
      type
        = build_varargs_function_type_list (objc_object_type,
                                            objc_super_type,
                                            objc_selector_type,
                                            NULL_TREE);
      umsg_super_decl = add_builtin_function (TAG_MSGSENDSUPER,
                                              type, 0, NOT_BUILT_IN,
                                              NULL, NULL_TREE);
      umsg_super_stret_decl = add_builtin_function (TAG_MSGSENDSUPER_STRET,
                                                    type, 0, NOT_BUILT_IN, 0,
                                                    NULL_TREE);
      TREE_NOTHROW (umsg_super_decl) = 0;
      TREE_NOTHROW (umsg_super_stret_decl) = 0;
    }
  else
    {
      /* GNU runtime messenger entry points.  */

      /* typedef id (*IMP)(id, SEL, ...); */
      tree ftype =
        build_varargs_function_type_list (objc_object_type,
                                          objc_object_type,
                                          objc_selector_type,
                                          NULL_TREE);
      tree IMP_type = build_pointer_type (ftype);

      /* IMP objc_msg_lookup (id, SEL); */
      type = build_function_type_list (IMP_type,
                                       objc_object_type,
                                       objc_selector_type,
                                       NULL_TREE);
      umsg_decl = add_builtin_function (TAG_MSGSEND,
                                        type, 0, NOT_BUILT_IN,
                                        NULL, NULL_TREE);
      TREE_NOTHROW (umsg_decl) = 0;

      /* IMP objc_msg_lookup_super (struct objc_super *, SEL); */
      type
        = build_function_type_list (IMP_type,
                                    objc_super_type,
                                    objc_selector_type,
                                    NULL_TREE);
      umsg_super_decl = add_builtin_function (TAG_MSGSENDSUPER,
                                              type, 0, NOT_BUILT_IN,
                                              NULL, NULL_TREE);
      TREE_NOTHROW (umsg_super_decl) = 0;

      /* The following GNU runtime entry point is called to initialize
         each module:

         __objc_exec_class (void *); */
      type
        = build_function_type_list (void_type_node,
                                    ptr_type_node,
                                    NULL_TREE);
      execclass_decl = add_builtin_function (TAG_EXECCLASS,
                                             type, 0, NOT_BUILT_IN,
                                             NULL, NULL_TREE);
    }

  /* id objc_getClass (const char *); */

  type = build_function_type_list (objc_object_type,
                                   const_string_type_node,
                                   NULL_TREE);

  objc_get_class_decl
    = add_builtin_function (TAG_GETCLASS, type, 0, NOT_BUILT_IN,
                            NULL, NULL_TREE);

  /* id objc_getMetaClass (const char *); */

  objc_get_meta_class_decl
    = add_builtin_function (TAG_GETMETACLASS, type, 0, NOT_BUILT_IN, NULL, NULL_TREE);

  build_class_template ();
  build_super_template ();
  build_protocol_template ();
  build_category_template ();
  build_objc_exception_stuff ();

  /* Declare objc_getProperty, object_setProperty and other property
     accessor helpers.  */
  build_objc_property_accessor_helpers ();

  if (flag_next_runtime)
    build_next_objc_exception_stuff ();

  /* static SEL _OBJC_SELECTOR_TABLE[]; */

  if (! flag_next_runtime)
    build_selector_table_decl ();

  /* Forward declare constant_string_id and constant_string_type.  */
  if (!constant_string_class_name)
    constant_string_class_name = default_constant_string_class_name;

  constant_string_id = get_identifier (constant_string_class_name);
  objc_declare_class (tree_cons (NULL_TREE, constant_string_id, NULL_TREE));

  /* Pre-build the following entities - for speed/convenience.  */
  self_id = get_identifier ("self");
  ucmd_id = get_identifier ("_cmd");

  /* Declare struct _objc_fast_enumeration_state { ... };  */
  build_fast_enumeration_state_template ();
  
  /* void objc_enumeration_mutation (id) */
  type = build_function_type (void_type_node,
                              tree_cons (NULL_TREE, objc_object_type, NULL_TREE));
  objc_enumeration_mutation_decl 
    = add_builtin_function (TAG_ENUMERATION_MUTATION, type, 0, NOT_BUILT_IN, 
                            NULL, NULL_TREE);
  TREE_NOTHROW (objc_enumeration_mutation_decl) = 0;

#ifdef OBJCPLUS
  pop_lang_context ();
#endif

  write_symbols = save_write_symbols;
  debug_hooks = save_hooks;
}

/* Ensure that the ivar list for NSConstantString/NXConstantString
   (or whatever was specified via `-fconstant-string-class')
   contains fields at least as large as the following three, so that
   the runtime can stomp on them with confidence:

   struct STRING_OBJECT_CLASS_NAME
   {
     Object isa;
     char *cString;
     unsigned int length;
   }; */

static int
check_string_class_template (void)
{
  tree field_decl = objc_get_class_ivars (constant_string_id);

#define AT_LEAST_AS_LARGE_AS(F, T) \
  (F && TREE_CODE (F) == FIELD_DECL \
     && (TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (F))) \
         >= TREE_INT_CST_LOW (TYPE_SIZE (T))))

  if (!AT_LEAST_AS_LARGE_AS (field_decl, ptr_type_node))
    return 0;

  field_decl = DECL_CHAIN (field_decl);
  if (!AT_LEAST_AS_LARGE_AS (field_decl, ptr_type_node))
    return 0;

  field_decl = DECL_CHAIN (field_decl);
  return AT_LEAST_AS_LARGE_AS (field_decl, unsigned_type_node);

#undef AT_LEAST_AS_LARGE_AS
}

/* Avoid calling `check_string_class_template ()' more than once.  */
static GTY(()) int string_layout_checked;

/* Construct an internal string layout to be used as a template for
   creating NSConstantString/NXConstantString instances.  */

static tree
objc_build_internal_const_str_type (void)
{
  tree type = (*lang_hooks.types.make_type) (RECORD_TYPE);
  tree fields = build_decl (input_location,
                            FIELD_DECL, NULL_TREE, ptr_type_node);
  tree field = build_decl (input_location,
                           FIELD_DECL, NULL_TREE, ptr_type_node);

  DECL_CHAIN (field) = fields; fields = field;
  field = build_decl (input_location,
                      FIELD_DECL, NULL_TREE, unsigned_type_node);
  DECL_CHAIN (field) = fields; fields = field;
  /* NB: The finish_builtin_struct() routine expects FIELD_DECLs in
     reverse order!  */
  finish_builtin_struct (type, "__builtin_ObjCString",
                         fields, NULL_TREE);

  return type;
}

/* Custom build_string which sets TREE_TYPE!  */

static tree
my_build_string (int len, const char *str)
{
  return fix_string_type (build_string (len, str));
}

/* Build a string with contents STR and length LEN and convert it to a
   pointer.  */

static tree
my_build_string_pointer (int len, const char *str)
{
  tree string = my_build_string (len, str);
  tree ptrtype = build_pointer_type (TREE_TYPE (TREE_TYPE (string)));
  return build1 (ADDR_EXPR, ptrtype, string);
}

static hashval_t
string_hash (const void *ptr)
{
  const_tree const str = ((const struct string_descriptor *)ptr)->literal;
  const unsigned char *p = (const unsigned char *) TREE_STRING_POINTER (str);
  int i, len = TREE_STRING_LENGTH (str);
  hashval_t h = len;

  for (i = 0; i < len; i++)
    h = ((h * 613) + p[i]);

  return h;
}

static int
string_eq (const void *ptr1, const void *ptr2)
{
  const_tree const str1 = ((const struct string_descriptor *)ptr1)->literal;
  const_tree const str2 = ((const struct string_descriptor *)ptr2)->literal;
  int len1 = TREE_STRING_LENGTH (str1);

  return (len1 == TREE_STRING_LENGTH (str2)
          && !memcmp (TREE_STRING_POINTER (str1), TREE_STRING_POINTER (str2),
                      len1));
}

/* Given a chain of STRING_CST's, build a static instance of
   NXConstantString which points at the concatenation of those
   strings.  We place the string object in the __string_objects
   section of the __OBJC segment.  The Objective-C runtime will
   initialize the isa pointers of the string objects to point at the
   NXConstantString class object.  */

tree
objc_build_string_object (tree string)
{
  tree constant_string_class;
  int length;
  tree fields, addr;
  struct string_descriptor *desc, key;
  void **loc;

  /* Prep the string argument.  */
  string = fix_string_type (string);
  TREE_SET_CODE (string, STRING_CST);
  length = TREE_STRING_LENGTH (string) - 1;

  /* The target may have different ideas on how to construct an ObjC string 
     literal.  On Darwin (Mac OS X), for example, we may wish to obtain a 
     constant CFString reference instead.
     At present, this is only supported for the NeXT runtime.  */
  if (flag_next_runtime && targetcm.objc_construct_string_object)
    {
      tree constructor = (*targetcm.objc_construct_string_object) (string);
      if (constructor)
        return build1 (NOP_EXPR, objc_object_type, constructor);
    }

  /* Check whether the string class being used actually exists and has the
     correct ivar layout.  */
  if (!string_layout_checked)
    {
      string_layout_checked = -1;
      constant_string_class = lookup_interface (constant_string_id);
      internal_const_str_type = objc_build_internal_const_str_type ();

      if (!constant_string_class
          || !(constant_string_type
               = CLASS_STATIC_TEMPLATE (constant_string_class)))
        error ("cannot find interface declaration for %qE",
               constant_string_id);
      /* The NSConstantString/NXConstantString ivar layout is now known.  */
      else if (!check_string_class_template ())
        error ("interface %qE does not have valid constant string layout",
               constant_string_id);
      /* For the NeXT runtime, we can generate a literal reference
         to the string class, don't need to run a constructor.  */
      else if (flag_next_runtime && !setup_string_decl ())
        error ("cannot find reference tag for class %qE",
               constant_string_id);
      else
        {
          string_layout_checked = 1;  /* Success!  */
          add_class_reference (constant_string_id);
        }
    }

  if (string_layout_checked == -1)
    return error_mark_node;

  /* Perhaps we already constructed a constant string just like this one? */
  key.literal = string;
  loc = htab_find_slot (string_htab, &key, INSERT);
  desc = (struct string_descriptor *) *loc;

  if (!desc)
    {
      tree var, constructor;
      VEC(constructor_elt,gc) *v = NULL;
      *loc = desc = ggc_alloc_string_descriptor ();
      desc->literal = string;

      /* GNU:    (NXConstantString *) & ((__builtin_ObjCString) { NULL, string, length })  */
      /* NeXT:   (NSConstantString *) & ((__builtin_ObjCString) { isa, string, length })   */
      fields = TYPE_FIELDS (internal_const_str_type);
      CONSTRUCTOR_APPEND_ELT (v, fields,
                              flag_next_runtime
                              ? build_unary_op (input_location,
                                                ADDR_EXPR, string_class_decl, 0)
                              : build_int_cst (NULL_TREE, 0));
      fields = DECL_CHAIN (fields);
      CONSTRUCTOR_APPEND_ELT (v, fields,
                              build_unary_op (input_location,
                                              ADDR_EXPR, string, 1));
      fields = DECL_CHAIN (fields);
      CONSTRUCTOR_APPEND_ELT (v, fields, build_int_cst (NULL_TREE, length));
      constructor = objc_build_constructor (internal_const_str_type, v);

      if (!flag_next_runtime)
        constructor
          = objc_add_static_instance (constructor, constant_string_type);
      else
        {
          var = build_decl (input_location,
                            CONST_DECL, NULL, TREE_TYPE (constructor));
          DECL_INITIAL (var) = constructor;
          TREE_STATIC (var) = 1;
          pushdecl_top_level (var);
          constructor = var;
        }
      desc->constructor = constructor;
    }

  addr = convert (build_pointer_type (constant_string_type),
                  build_unary_op (input_location,
                                  ADDR_EXPR, desc->constructor, 1));

  return addr;
}

/* Declare a static instance of CLASS_DECL initialized by CONSTRUCTOR.  */

static GTY(()) int num_static_inst;

static tree
objc_add_static_instance (tree constructor, tree class_decl)
{
  tree *chain, decl;
  char buf[256];

  /* Find the list of static instances for the CLASS_DECL.  Create one if
     not found.  */
  for (chain = &objc_static_instances;
       *chain && TREE_VALUE (*chain) != class_decl;
       chain = &TREE_CHAIN (*chain));
  if (!*chain)
    {
      *chain = tree_cons (NULL_TREE, class_decl, NULL_TREE);
      add_objc_string (OBJC_TYPE_NAME (class_decl), class_names);
    }

  sprintf (buf, "_OBJC_INSTANCE_%d", num_static_inst++);
  decl = build_decl (input_location,
                     VAR_DECL, get_identifier (buf), class_decl);
  TREE_STATIC (decl) = 1;
  DECL_ARTIFICIAL (decl) = 1;
  TREE_USED (decl) = 1;
  DECL_INITIAL (decl) = constructor;

  /* We may be writing something else just now.
     Postpone till end of input.  */
  DECL_DEFER_OUTPUT (decl) = 1;
  pushdecl_top_level (decl);
  rest_of_decl_compilation (decl, 1, 0);

  /* Add the DECL to the head of this CLASS' list.  */
  TREE_PURPOSE (*chain) = tree_cons (NULL_TREE, decl, TREE_PURPOSE (*chain));

  return decl;
}

/* Build a static constant CONSTRUCTOR
   with type TYPE and elements ELTS.  */

static tree
objc_build_constructor (tree type, VEC(constructor_elt,gc) *elts)
{
  tree constructor = build_constructor (type, elts);

  TREE_CONSTANT (constructor) = 1;
  TREE_STATIC (constructor) = 1;
  TREE_READONLY (constructor) = 1;

#ifdef OBJCPLUS
  /* Adjust for impedance mismatch.  We should figure out how to build
     CONSTRUCTORs that consistently please both the C and C++ gods.  */
  if (!VEC_index (constructor_elt, elts, 0)->index)
    TREE_TYPE (constructor) = init_list_type_node;
#endif

  return constructor;
}
\f
/* Take care of defining and initializing _OBJC_SYMBOLS.  */

/* Predefine the following data type:

   struct _objc_symtab
   {
     long sel_ref_cnt;
     SEL *refs;
     short cls_def_cnt;
     short cat_def_cnt;
     void *defs[cls_def_cnt + cat_def_cnt];
   }; */

static void
build_objc_symtab_template (void)
{
  tree fields, *chain = NULL;

  objc_symtab_template = objc_start_struct (get_identifier (UTAG_SYMTAB));

  /* long sel_ref_cnt; */
  fields = add_field_decl (long_integer_type_node, "sel_ref_cnt", &chain);

  /* SEL *refs; */
  add_field_decl (build_pointer_type (objc_selector_type), "refs", &chain);

  /* short cls_def_cnt; */
  add_field_decl (short_integer_type_node, "cls_def_cnt", &chain);

  /* short cat_def_cnt; */
  add_field_decl (short_integer_type_node, "cat_def_cnt", &chain);

  if (imp_count || cat_count || !flag_next_runtime)
    {
      /* void *defs[imp_count + cat_count (+ 1)]; */
      /* NB: The index is one less than the size of the array.  */
      int index = imp_count + cat_count + (flag_next_runtime ? -1: 0);
      tree array_type = build_sized_array_type (ptr_type_node, index + 1);
      add_field_decl (array_type, "defs", &chain);
    }

  objc_finish_struct (objc_symtab_template, fields);
}

/* Create the initial value for the `defs' field of _objc_symtab.
   This is a CONSTRUCTOR.  */

static tree
init_def_list (tree type)
{
  tree expr;
  struct imp_entry *impent;
  VEC(constructor_elt,gc) *v = NULL;

  if (imp_count)
    for (impent = imp_list; impent; impent = impent->next)
      {
        if (TREE_CODE (impent->imp_context) == CLASS_IMPLEMENTATION_TYPE)
          {
            expr = build_unary_op (input_location,
                                   ADDR_EXPR, impent->class_decl, 0);
            CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
          }
      }

  if (cat_count)
    for (impent = imp_list; impent; impent = impent->next)
      {
        if (TREE_CODE (impent->imp_context) == CATEGORY_IMPLEMENTATION_TYPE)
          {
            expr = build_unary_op (input_location,
                                   ADDR_EXPR, impent->class_decl, 0);
            CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
          }
      }

  if (!flag_next_runtime)
    {
      /* statics = { ..., _OBJC_STATIC_INSTANCES, ... }  */
      if (static_instances_decl)
        expr = build_unary_op (input_location,
                               ADDR_EXPR, static_instances_decl, 0);
      else
        expr = integer_zero_node;

      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
    }

  return objc_build_constructor (type, v);
}

/* Construct the initial value for all of _objc_symtab.  */

static tree
init_objc_symtab (tree type)
{
  VEC(constructor_elt,gc) *v = NULL;

  /* sel_ref_cnt = { ..., 5, ... } */

  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
                          build_int_cst (long_integer_type_node, 0));

  /* refs = { ..., _OBJC_SELECTOR_TABLE, ... } */

  if (flag_next_runtime || ! sel_ref_chain)
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, convert (
                                        build_pointer_type (objc_selector_type),
                                                        integer_zero_node));
  else
    {
      tree expr = build_unary_op (input_location, ADDR_EXPR,
                                  UOBJC_SELECTOR_TABLE_decl, 1);

      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
                              convert (build_pointer_type (objc_selector_type),
                                       expr));
    }

  /* cls_def_cnt = { ..., 5, ... } */

  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, 
                          build_int_cst (short_integer_type_node, imp_count));

  /* cat_def_cnt = { ..., 5, ... } */

  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, 
                          build_int_cst (short_integer_type_node, cat_count));

  /* cls_def = { ..., { &Foo, &Bar, ...}, ... } */

  if (imp_count || cat_count || !flag_next_runtime)
    {

      tree field = TYPE_FIELDS (type);
      field = DECL_CHAIN (DECL_CHAIN (DECL_CHAIN (DECL_CHAIN (field))));

      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, init_def_list (TREE_TYPE (field)));
    }

  return objc_build_constructor (type, v);
}

/* Generate forward declarations for metadata such as
  'OBJC_CLASS_...'.  */

static tree
build_metadata_decl (const char *name, tree type)
{
  tree decl;

  /* struct TYPE NAME_<name>; */
  decl = start_var_decl (type, synth_id_with_class_suffix
                               (name,
                                objc_implementation_context));

  return decl;
}

/* Push forward-declarations of all the categories so that
   init_def_list can use them in a CONSTRUCTOR.  */

static void
forward_declare_categories (void)
{
  struct imp_entry *impent;
  tree sav = objc_implementation_context;

  for (impent = imp_list; impent; impent = impent->next)
    {
      if (TREE_CODE (impent->imp_context) == CATEGORY_IMPLEMENTATION_TYPE)
        {
          /* Set an invisible arg to synth_id_with_class_suffix.  */
          objc_implementation_context = impent->imp_context;
          /* extern struct objc_category _OBJC_CATEGORY_<name>; */
          impent->class_decl = build_metadata_decl ("_OBJC_CATEGORY",
                                                    objc_category_template);
        }
    }
  objc_implementation_context = sav;
}

/* Create the declaration of _OBJC_SYMBOLS, with type `struct _objc_symtab'
   and initialized appropriately.  */

static void
generate_objc_symtab_decl (void)
{
 
  build_objc_symtab_template ();
  UOBJC_SYMBOLS_decl = start_var_decl (objc_symtab_template, "_OBJC_SYMBOLS");
  finish_var_decl (UOBJC_SYMBOLS_decl,
                   init_objc_symtab (TREE_TYPE (UOBJC_SYMBOLS_decl)));
}
\f
static tree
init_module_descriptor (tree type)
{
  tree expr;
  VEC(constructor_elt,gc) *v = NULL;

  /* version = { 1, ... } */

  expr = build_int_cst (long_integer_type_node, OBJC_VERSION);
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);

  /* size = { ..., sizeof (struct _objc_module), ... } */

  expr = convert (long_integer_type_node,
                  size_in_bytes (objc_module_template));
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);

  /* Don't provide any file name for security reasons. */
  /* name = { ..., "", ... } */

  expr = add_objc_string (get_identifier (""), class_names);
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);

  /* symtab = { ..., _OBJC_SYMBOLS, ... } */

  if (UOBJC_SYMBOLS_decl)
    expr = build_unary_op (input_location,
                           ADDR_EXPR, UOBJC_SYMBOLS_decl, 0);
  else
    expr = null_pointer_node;
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);

  return objc_build_constructor (type, v);
}

/* Write out the data structures to describe Objective C classes defined.

   struct _objc_module { ... } _OBJC_MODULE = { ... };   */

static void
build_module_descriptor (void)
{
  tree decls, *chain = NULL;

#ifdef OBJCPLUS
  push_lang_context (lang_name_c); /* extern "C" */
#endif

  objc_module_template = objc_start_struct (get_identifier (UTAG_MODULE));

  /* long version; */
  decls = add_field_decl (long_integer_type_node, "version", &chain);

  /* long size; */
  add_field_decl (long_integer_type_node, "size", &chain);

  /* char *name; */
  add_field_decl (string_type_node, "name", &chain);

  /* struct _objc_symtab *symtab; */
  add_field_decl (build_pointer_type (xref_tag (RECORD_TYPE,
                                                get_identifier (UTAG_SYMTAB))),
                  "symtab", &chain);

  objc_finish_struct (objc_module_template, decls);

  /* Create an instance of "_objc_module".  */
  UOBJC_MODULES_decl = start_var_decl (objc_module_template, "_OBJC_MODULES");
  /* This is the root of the metadata for defined classes and categories, it
     is referenced by the runtime and, therefore, needed.  */
  DECL_PRESERVE_P (UOBJC_MODULES_decl) = 1;
  finish_var_decl (UOBJC_MODULES_decl,
                   init_module_descriptor (TREE_TYPE (UOBJC_MODULES_decl)));

#ifdef OBJCPLUS
  pop_lang_context ();
#endif
}

/* The GNU runtime requires us to provide a static initializer function
   for each module:

   static void __objc_gnu_init (void) {
     __objc_exec_class (&L_OBJC_MODULES);
   }  */

static void
build_module_initializer_routine (void)
{
  tree body;

#ifdef OBJCPLUS
  push_lang_context (lang_name_c); /* extern "C" */
#endif

  objc_push_parm (build_decl (input_location,
                              PARM_DECL, NULL_TREE, void_type_node));
#ifdef OBJCPLUS
  objc_start_function (get_identifier (TAG_GNUINIT),
                       build_function_type_list (void_type_node, NULL_TREE),
                       NULL_TREE, NULL_TREE);
#else
  objc_start_function (get_identifier (TAG_GNUINIT),
                       build_function_type_list (void_type_node, NULL_TREE),
                       NULL_TREE, objc_get_parm_info (0));
#endif
  body = c_begin_compound_stmt (true);
  add_stmt (build_function_call
            (input_location,
             execclass_decl,
             build_tree_list
             (NULL_TREE,
              build_unary_op (input_location, ADDR_EXPR,
                              UOBJC_MODULES_decl, 0))));
  add_stmt (c_end_compound_stmt (input_location, body, true));

  TREE_PUBLIC (current_function_decl) = 0;

#ifndef OBJCPLUS
  /* For Objective-C++, we will need to call __objc_gnu_init
     from objc_generate_static_init_call() below.  */
  DECL_STATIC_CONSTRUCTOR (current_function_decl) = 1;
#endif

  GNU_INIT_decl = current_function_decl;
  finish_function ();

#ifdef OBJCPLUS
    pop_lang_context ();
#endif
}

#ifdef OBJCPLUS
/* Return 1 if the __objc_gnu_init function has been synthesized and needs
   to be called by the module initializer routine.  */

int
objc_static_init_needed_p (void)
{
  return (GNU_INIT_decl != NULL_TREE);
}

/* Generate a call to the __objc_gnu_init initializer function.  */

tree
objc_generate_static_init_call (tree ctors ATTRIBUTE_UNUSED)
{
  add_stmt (build_stmt (input_location, EXPR_STMT,
                        build_function_call (input_location,
                                             GNU_INIT_decl, NULL_TREE)));

  return ctors;
}
#endif /* OBJCPLUS */

/* Return the DECL of the string IDENT in the SECTION.  */

static tree
get_objc_string_decl (tree ident, enum string_section section)
{
  tree chain;

  switch (section)
    {
    case class_names:
      chain = class_names_chain;
      break;
    case meth_var_names:
      chain = meth_var_names_chain;
      break;
    case meth_var_types:
      chain = meth_var_types_chain;
      break;
    default:
      gcc_unreachable ();
    }

  for (; chain != 0; chain = TREE_CHAIN (chain))
    if (TREE_VALUE (chain) == ident)
      return (TREE_PURPOSE (chain));

  gcc_unreachable ();
  return NULL_TREE;
}

/* Output references to all statically allocated objects.  Return the DECL
   for the array built.  */

static void
generate_static_references (void)
{
  tree expr = NULL_TREE;
  tree class_name, klass, decl;
  tree cl_chain, in_chain, type
    = build_array_type (build_pointer_type (void_type_node), NULL_TREE);
  int num_inst, num_class;
  char buf[256];
  VEC(constructor_elt,gc) *decls = NULL;

  if (flag_next_runtime)
    gcc_unreachable ();

  for (cl_chain = objc_static_instances, num_class = 0;
       cl_chain; cl_chain = TREE_CHAIN (cl_chain), num_class++)
    {
      VEC(constructor_elt,gc) *v = NULL;

      for (num_inst = 0, in_chain = TREE_PURPOSE (cl_chain);
           in_chain; num_inst++, in_chain = TREE_CHAIN (in_chain));

      sprintf (buf, "_OBJC_STATIC_INSTANCES_%d", num_class);
      decl = start_var_decl (type, buf);

      /* Output {class_name, ...}.  */
      klass = TREE_VALUE (cl_chain);
      class_name = get_objc_string_decl (OBJC_TYPE_NAME (klass), class_names);
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
                              build_unary_op (input_location, 
                                              ADDR_EXPR, class_name, 1));

      /* Output {..., instance, ...}.  */
      for (in_chain = TREE_PURPOSE (cl_chain);
           in_chain; in_chain = TREE_CHAIN (in_chain))
        {
          expr = build_unary_op (input_location,
                                 ADDR_EXPR, TREE_VALUE (in_chain), 1);
          CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
        }

      /* Output {..., NULL}.  */
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));

      expr = objc_build_constructor (TREE_TYPE (decl), v);
      finish_var_decl (decl, expr);
      CONSTRUCTOR_APPEND_ELT (decls, NULL_TREE,
                              build_unary_op (input_location,
                                              ADDR_EXPR, decl, 1));
    }

  CONSTRUCTOR_APPEND_ELT (decls, NULL_TREE, build_int_cst (NULL_TREE, 0));
  expr = objc_build_constructor (type, decls);
  static_instances_decl = start_var_decl (type, "_OBJC_STATIC_INSTANCES");
  finish_var_decl (static_instances_decl, expr);
}

static GTY(()) int selector_reference_idx;

static tree
build_selector_reference_decl (void)
{
  tree decl;
  char buf[256];

  sprintf (buf, "_OBJC_SELECTOR_REFERENCES_%d", selector_reference_idx++);
  decl = start_var_decl (objc_selector_type, buf);

  return decl;
}

static void
build_selector_table_decl (void)
{
  tree temp;

  if (flag_typed_selectors)
    {
      build_selector_template ();
      temp = build_array_type (objc_selector_template, NULL_TREE);
    }
  else
    temp = build_array_type (objc_selector_type, NULL_TREE);

  UOBJC_SELECTOR_TABLE_decl = start_var_decl (temp, "_OBJC_SELECTOR_TABLE");
}

/* Just a handy wrapper for add_objc_string.  */

static tree
build_selector (tree ident)
{
  return convert (objc_selector_type,
                  add_objc_string (ident, meth_var_names));
}

/* Used only by build_*_selector_translation_table (). */
static void
diagnose_missing_method (tree meth, location_t here)
{
  tree method_chain;
  bool found = false;
  for (method_chain = meth_var_names_chain;
       method_chain;
       method_chain = TREE_CHAIN (method_chain))
    {
      if (TREE_VALUE (method_chain) == meth)
        {
          found = true;
          break;
        }
     }

  if (!found)
    warning_at (here, 0, "creating selector for nonexistent method %qE",
                        meth);
}

static void
build_next_selector_translation_table (void)
{
  tree chain;
  for (chain = sel_ref_chain; chain; chain = TREE_CHAIN (chain))
    {
      tree expr;
      tree decl = TREE_PURPOSE (chain);
      if (warn_selector && objc_implementation_context)
        {
          location_t loc;
          if (decl) 
            loc = DECL_SOURCE_LOCATION (decl);
          else
            loc = input_location;
          diagnose_missing_method (TREE_VALUE (chain), loc);
        }

      expr = build_selector (TREE_VALUE (chain));

      if (decl)
        {
          /* Entries of this form are used for references to methods.
          The runtime re-writes these on start-up, but the compiler can't see 
          that and optimizes it away unless we force it.  */
          DECL_PRESERVE_P (decl) = 1;
          finish_var_decl (decl, expr);
        }
    }
}

static void
build_gnu_selector_translation_table (void)
{
  tree chain;
/*  int offset = 0;
  tree decl = NULL_TREE;*/
  VEC(constructor_elt,gc) *inits = NULL;

  for (chain = sel_ref_chain; chain; chain = TREE_CHAIN (chain))
    {
      tree expr;

      if (warn_selector && objc_implementation_context)
        diagnose_missing_method (TREE_VALUE (chain), input_location);

      expr = build_selector (TREE_VALUE (chain));
      /* add one for the '\0' character 
      offset += IDENTIFIER_LENGTH (TREE_VALUE (chain)) + 1;*/

        {
          if (flag_typed_selectors)
            {
              VEC(constructor_elt,gc) *v = NULL;
              tree encoding = get_proto_encoding (TREE_PURPOSE (chain));
              CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
              CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, encoding);
              expr = objc_build_constructor (objc_selector_template, v);
            }

          CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, expr);
        }
    } /* each element in the chain */

    {
      /* Cause the selector table (previously forward-declared)
         to be actually output.  */
      tree expr;

      if (flag_typed_selectors)
        {
          VEC(constructor_elt,gc) *v = NULL;
          CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, integer_zero_node);
          CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, integer_zero_node);
          expr = objc_build_constructor (objc_selector_template, v);
        }
      else
        expr = integer_zero_node;

      CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, expr);
      expr = objc_build_constructor (TREE_TYPE (UOBJC_SELECTOR_TABLE_decl),
                                     inits);
      finish_var_decl (UOBJC_SELECTOR_TABLE_decl, expr);
    }
}

static tree
get_proto_encoding (tree proto)
{
  tree encoding;
  if (proto)
    {
      if (! METHOD_ENCODING (proto))
        {
          encoding = encode_method_prototype (proto);
          METHOD_ENCODING (proto) = encoding;
        }
      else
        encoding = METHOD_ENCODING (proto);

      return add_objc_string (encoding, meth_var_types);
    }
  else
    return build_int_cst (NULL_TREE, 0);
}

/* sel_ref_chain is a list whose "value" fields will be instances of
   identifier_node that represent the selector.  LOC is the location of
   the @selector.  */

static tree
build_typed_selector_reference (location_t loc, tree ident, tree prototype)
{
  tree *chain = &sel_ref_chain;
  tree expr;
  int index = 0;

  while (*chain)
    {
      if (TREE_PURPOSE (*chain) == prototype && TREE_VALUE (*chain) == ident)
        goto return_at_index;

      index++;
      chain = &TREE_CHAIN (*chain);
    }

  *chain = tree_cons (prototype, ident, NULL_TREE);

 return_at_index:
  expr = build_unary_op (loc, ADDR_EXPR,
                         build_array_ref (loc, UOBJC_SELECTOR_TABLE_decl,
                                          build_int_cst (NULL_TREE, index)),
                         1);
  return convert (objc_selector_type, expr);
}

static tree
build_selector_reference (location_t loc, tree ident)
{
  tree *chain = &sel_ref_chain;
  tree expr;
  int index = 0;

  while (*chain)
    {
      if (TREE_VALUE (*chain) == ident)
        return (flag_next_runtime
                ? TREE_PURPOSE (*chain)
                : build_array_ref (loc, UOBJC_SELECTOR_TABLE_decl,
                                   build_int_cst (NULL_TREE, index)));

      index++;
      chain = &TREE_CHAIN (*chain);
    }

  expr = (flag_next_runtime ? build_selector_reference_decl (): NULL_TREE);

  *chain = tree_cons (expr, ident, NULL_TREE);

  return (flag_next_runtime
          ? expr
          : build_array_ref (loc, UOBJC_SELECTOR_TABLE_decl,
                             build_int_cst (NULL_TREE, index)));
}

static GTY(()) int class_reference_idx;

static tree
build_class_reference_decl (void)
{
  tree decl;
  char buf[256];

  sprintf (buf, "_OBJC_CLASS_REFERENCES_%d", class_reference_idx++);
  decl = start_var_decl (objc_class_type, buf);

  return decl;
}

/* Create a class reference, but don't create a variable to reference
   it.  */

static void
add_class_reference (tree ident)
{
  tree chain;

  if ((chain = cls_ref_chain))
    {
      tree tail;
      do
        {
          if (ident == TREE_VALUE (chain))
            return;

          tail = chain;
          chain = TREE_CHAIN (chain);
        }
      while (chain);

      /* Append to the end of the list */
      TREE_CHAIN (tail) = tree_cons (NULL_TREE, ident, NULL_TREE);
    }
  else
    cls_ref_chain = tree_cons (NULL_TREE, ident, NULL_TREE);
}

/* Get a class reference, creating it if necessary.  Also create the
   reference variable.  */

tree
objc_get_class_reference (tree ident)
{
  tree orig_ident = (DECL_P (ident)
                     ? DECL_NAME (ident)
                     : TYPE_P (ident)
                     ? OBJC_TYPE_NAME (ident)
                     : ident);
  bool local_scope = false;

#ifdef OBJCPLUS
  if (processing_template_decl)
    /* Must wait until template instantiation time.  */
    return build_min_nt (CLASS_REFERENCE_EXPR, ident);
#endif

  if (TREE_CODE (ident) == TYPE_DECL)
    ident = (DECL_ORIGINAL_TYPE (ident)
             ? DECL_ORIGINAL_TYPE (ident)
             : TREE_TYPE (ident));

#ifdef OBJCPLUS
  if (TYPE_P (ident)
      && CP_TYPE_CONTEXT (ident) != global_namespace)
    local_scope = true;
#endif

  if (local_scope || !(ident = objc_is_class_name (ident)))
    {
      error ("%qE is not an Objective-C class name or alias",
             orig_ident);
      return error_mark_node;
    }

  if (flag_next_runtime && !flag_zero_link)
    {
      tree *chain;
      tree decl;

      for (chain = &cls_ref_chain; *chain; chain = &TREE_CHAIN (*chain))
        if (TREE_VALUE (*chain) == ident)
          {
            if (! TREE_PURPOSE (*chain))
              TREE_PURPOSE (*chain) = build_class_reference_decl ();

            return TREE_PURPOSE (*chain);
          }

      decl = build_class_reference_decl ();
      *chain = tree_cons (decl, ident, NULL_TREE);
      return decl;
    }
  else
    {
      tree params;

      add_class_reference (ident);

      params = build_tree_list (NULL_TREE,
                                my_build_string_pointer
                                (IDENTIFIER_LENGTH (ident) + 1,
                                 IDENTIFIER_POINTER (ident)));

      assemble_external (objc_get_class_decl);
      return build_function_call (input_location, objc_get_class_decl, params);
    }
}

/* For each string section we have a chain which maps identifier nodes
   to decls for the strings.  */

static GTY(()) int class_names_idx;
static GTY(()) int meth_var_names_idx;
static GTY(()) int meth_var_types_idx;

static tree
add_objc_string (tree ident, enum string_section section)
{
  tree *chain, decl, type, string_expr;
  char buf[256];
  
  buf[0] = 0;
  switch (section)
    {
    case class_names:
      chain = &class_names_chain;
      sprintf (buf, "_OBJC_CLASS_NAME_%d", class_names_idx++);
      break;
    case meth_var_names:
      chain = &meth_var_names_chain;
      sprintf (buf, "_OBJC_METH_VAR_NAME_%d", meth_var_names_idx++);
      break;
    case meth_var_types:
      chain = &meth_var_types_chain;
      sprintf (buf, "_OBJC_METH_VAR_TYPE_%d", meth_var_types_idx++);
      break;
    default:
      gcc_unreachable ();
    }

  while (*chain)
    {
      if (TREE_VALUE (*chain) == ident)
        return convert (string_type_node,
                        build_unary_op (input_location,
                                        ADDR_EXPR, TREE_PURPOSE (*chain), 1));

      chain = &TREE_CHAIN (*chain);
    }

  type = build_sized_array_type (char_type_node, IDENTIFIER_LENGTH (ident) + 1);
  decl = start_var_decl (type, buf);
  string_expr = my_build_string (IDENTIFIER_LENGTH (ident) + 1,
                                 IDENTIFIER_POINTER (ident));
  TREE_CONSTANT (decl) = 1;
  finish_var_decl (decl, string_expr);

  *chain = tree_cons (decl, ident, NULL_TREE);

  return convert (string_type_node, build_unary_op (input_location,
                                                    ADDR_EXPR, decl, 1));
}

void
objc_declare_alias (tree alias_ident, tree class_ident)
{
  tree underlying_class;

#ifdef OBJCPLUS
  if (current_namespace != global_namespace) {
    error ("Objective-C declarations may only appear in global scope");
  }
#endif /* OBJCPLUS */

  if (!(underlying_class = objc_is_class_name (class_ident)))
    warning (0, "cannot find class %qE", class_ident);
  else if (objc_is_class_name (alias_ident))
    warning (0, "class %qE already exists", alias_ident);
  else
    {
      /* Implement @compatibility_alias as a typedef.  */
#ifdef OBJCPLUS
      push_lang_context (lang_name_c); /* extern "C" */
#endif
      lang_hooks.decls.pushdecl (build_decl
                                 (input_location,
                                  TYPE_DECL,
                                  alias_ident,
                                  xref_tag (RECORD_TYPE, underlying_class)));
#ifdef OBJCPLUS
      pop_lang_context ();
#endif
      hash_class_name_enter (als_name_hash_list, alias_ident, 
                             underlying_class);
    }
}

void
objc_declare_class (tree ident_list)
{
  tree list;
#ifdef OBJCPLUS
  if (current_namespace != global_namespace) {
    error ("Objective-C declarations may only appear in global scope");
  }
#endif /* OBJCPLUS */

  for (list = ident_list; list; list = TREE_CHAIN (list))
    {
      tree ident = TREE_VALUE (list);

      if (! objc_is_class_name (ident))
        {
          tree record = lookup_name (ident), type = record;

          if (record)
            {
              if (TREE_CODE (record) == TYPE_DECL)
                type = DECL_ORIGINAL_TYPE (record) ? 
                        DECL_ORIGINAL_TYPE (record) : 
                        TREE_TYPE (record);

              if (!TYPE_HAS_OBJC_INFO (type)
                  || !TYPE_OBJC_INTERFACE (type))
                {
                  error ("%qE redeclared as different kind of symbol",
                         ident);
                  error ("previous declaration of %q+D",
                         record);
                }
            }

          record = xref_tag (RECORD_TYPE, ident);
          INIT_TYPE_OBJC_INFO (record);
          TYPE_OBJC_INTERFACE (record) = ident;
          hash_class_name_enter (cls_name_hash_list, ident, NULL_TREE);
        }
    }
}

tree
objc_is_class_name (tree ident)
{
  hash target;

  if (ident && TREE_CODE (ident) == IDENTIFIER_NODE
      && identifier_global_value (ident))
    ident = identifier_global_value (ident);
  while (ident && TREE_CODE (ident) == TYPE_DECL && DECL_ORIGINAL_TYPE (ident))
    ident = OBJC_TYPE_NAME (DECL_ORIGINAL_TYPE (ident));

  if (ident && TREE_CODE (ident) == RECORD_TYPE)
    ident = OBJC_TYPE_NAME (ident);
#ifdef OBJCPLUS
  if (ident && TREE_CODE (ident) == TYPE_DECL)
    {
      tree type = TREE_TYPE (ident);
      if (type && TREE_CODE (type) == TEMPLATE_TYPE_PARM)
        return NULL_TREE;
      ident = DECL_NAME (ident);
    }
#endif
  if (!ident || TREE_CODE (ident) != IDENTIFIER_NODE)
    return NULL_TREE;

  if (lookup_interface (ident))
    return ident;

  target = hash_class_name_lookup (cls_name_hash_list, ident);
  if (target)
    return target->key;

  target = hash_class_name_lookup (als_name_hash_list, ident);
  if (target)
    {
      gcc_assert (target->list && target->list->value);
      return target->list->value;
    }

  return 0;
}

/* Check whether TYPE is either 'id' or 'Class'.  */

tree
objc_is_id (tree type)
{
  if (type && TREE_CODE (type) == IDENTIFIER_NODE
      && identifier_global_value (type))
    type = identifier_global_value (type);

  if (type && TREE_CODE (type) == TYPE_DECL)
    type = TREE_TYPE (type);

  /* NB: This function may be called before the ObjC front-end has
     been initialized, in which case OBJC_OBJECT_TYPE will (still) be NULL.  */
  return (objc_object_type && type
          && (IS_ID (type) || IS_CLASS (type) || IS_SUPER (type))
          ? type
          : NULL_TREE);
}

/* Check whether TYPE is either 'id', 'Class', or a pointer to an ObjC
   class instance.  This is needed by other parts of the compiler to
   handle ObjC types gracefully.  */

tree
objc_is_object_ptr (tree type)
{
  tree ret;

  type = TYPE_MAIN_VARIANT (type);
  if (!POINTER_TYPE_P (type))
    return 0;

  ret = objc_is_id (type);
  if (!ret)
    ret = objc_is_class_name (TREE_TYPE (type));

  return ret;
}

static int
objc_is_gcable_type (tree type, int or_strong_p)
{
  tree name;

  if (!TYPE_P (type))
    return 0;
  if (objc_is_id (TYPE_MAIN_VARIANT (type)))
    return 1;
  if (or_strong_p && lookup_attribute ("objc_gc", TYPE_ATTRIBUTES (type)))
    return 1;
  if (TREE_CODE (type) != POINTER_TYPE && TREE_CODE (type) != INDIRECT_REF)
    return 0;
  type = TREE_TYPE (type);
  if (TREE_CODE (type) != RECORD_TYPE)
    return 0;
  name = TYPE_NAME (type);
  return (objc_is_class_name (name) != NULL_TREE);
}

static tree
objc_substitute_decl (tree expr, tree oldexpr, tree newexpr)
{
  if (expr == oldexpr)
    return newexpr;

  switch (TREE_CODE (expr))
    {
    case COMPONENT_REF:
      return objc_build_component_ref
             (objc_substitute_decl (TREE_OPERAND (expr, 0),
                                    oldexpr,
                                    newexpr),
              DECL_NAME (TREE_OPERAND (expr, 1)));
    case ARRAY_REF:
      return build_array_ref (input_location,
                              objc_substitute_decl (TREE_OPERAND (expr, 0),
                                                    oldexpr,
                                                    newexpr),
                              TREE_OPERAND (expr, 1));
    case INDIRECT_REF:
      return build_indirect_ref (input_location,
                                 objc_substitute_decl (TREE_OPERAND (expr, 0),
                                                       oldexpr,
                                                       newexpr), RO_ARROW);
    default:
      return expr;
    }
}

static tree
objc_build_ivar_assignment (tree outervar, tree lhs, tree rhs)
{
  tree func_params;
  /* The LHS parameter contains the expression 'outervar->memberspec';
     we need to transform it into '&((typeof(outervar) *) 0)->memberspec',
     where memberspec may be arbitrarily complex (e.g., 'g->f.d[2].g[3]').
  */
  tree offs
    = objc_substitute_decl
      (lhs, outervar, convert (TREE_TYPE (outervar), integer_zero_node));
  tree func
    = (flag_objc_direct_dispatch
       ? objc_assign_ivar_fast_decl
       : objc_assign_ivar_decl);

  offs = convert (integer_type_node, build_unary_op (input_location,
                                                     ADDR_EXPR, offs, 0));
  offs = fold (offs);
  func_params = tree_cons (NULL_TREE,
        convert (objc_object_type, rhs),
            tree_cons (NULL_TREE, convert (objc_object_type, outervar),
                tree_cons (NULL_TREE, offs,
                    NULL_TREE)));

  assemble_external (func);
  return build_function_call (input_location, func, func_params);
}

static tree
objc_build_global_assignment (tree lhs, tree rhs)
{
  tree func_params = tree_cons (NULL_TREE,
        convert (objc_object_type, rhs),
            tree_cons (NULL_TREE, convert (build_pointer_type (objc_object_type),
                      build_unary_op (input_location, ADDR_EXPR, lhs, 0)),
                    NULL_TREE));

  assemble_external (objc_assign_global_decl);
  return build_function_call (input_location, 
                              objc_assign_global_decl, func_params);
}

static tree
objc_build_strong_cast_assignment (tree lhs, tree rhs)
{
  tree func_params = tree_cons (NULL_TREE,
        convert (objc_object_type, rhs),
            tree_cons (NULL_TREE, convert (build_pointer_type (objc_object_type),
                      build_unary_op (input_location, ADDR_EXPR, lhs, 0)),
                    NULL_TREE));

  assemble_external (objc_assign_strong_cast_decl);
  return build_function_call (input_location,
                              objc_assign_strong_cast_decl, func_params);
}

static int
objc_is_gcable_p (tree expr)
{
  return (TREE_CODE (expr) == COMPONENT_REF
          ? objc_is_gcable_p (TREE_OPERAND (expr, 1))
          : TREE_CODE (expr) == ARRAY_REF
          ? (objc_is_gcable_p (TREE_TYPE (expr))
             || objc_is_gcable_p (TREE_OPERAND (expr, 0)))
          : TREE_CODE (expr) == ARRAY_TYPE
          ? objc_is_gcable_p (TREE_TYPE (expr))
          : TYPE_P (expr)
          ? objc_is_gcable_type (expr, 1)
          : (objc_is_gcable_p (TREE_TYPE (expr))
             || (DECL_P (expr)
                 && lookup_attribute ("objc_gc", DECL_ATTRIBUTES (expr)))));
}

static int
objc_is_ivar_reference_p (tree expr)
{
  return (TREE_CODE (expr) == ARRAY_REF
          ? objc_is_ivar_reference_p (TREE_OPERAND (expr, 0))
          : TREE_CODE (expr) == COMPONENT_REF
          ? TREE_CODE (TREE_OPERAND (expr, 1)) == FIELD_DECL
          : 0);
}

static int
objc_is_global_reference_p (tree expr)
{
  return (TREE_CODE (expr) == INDIRECT_REF || TREE_CODE (expr) == PLUS_EXPR
          ? objc_is_global_reference_p (TREE_OPERAND (expr, 0))
          : DECL_P (expr)
          ? (DECL_FILE_SCOPE_P (expr) || TREE_STATIC (expr))
          : 0);
}

tree
objc_generate_write_barrier (tree lhs, enum tree_code modifycode, tree rhs)
{
  tree result = NULL_TREE, outer;
  int strong_cast_p = 0, outer_gc_p = 0, indirect_p = 0;

  /* See if we have any lhs casts, and strip them out.  NB: The lvalue casts
     will have been transformed to the form '*(type *)&expr'.  */
  if (TREE_CODE (lhs) == INDIRECT_REF)
    {
      outer = TREE_OPERAND (lhs, 0);

      while (!strong_cast_p
             && (CONVERT_EXPR_P (outer)
                 || TREE_CODE (outer) == NON_LVALUE_EXPR))
        {
          tree lhstype = TREE_TYPE (outer);

          /* Descend down the cast chain, and record the first objc_gc
             attribute found.  */
          if (POINTER_TYPE_P (lhstype))
            {
              tree attr
                = lookup_attribute ("objc_gc",
                                    TYPE_ATTRIBUTES (TREE_TYPE (lhstype)));

              if (attr)
                strong_cast_p = 1;
            }

          outer = TREE_OPERAND (outer, 0);
        }
    }

  /* If we have a __strong cast, it trumps all else.  */
  if (strong_cast_p)
    {
      if (modifycode != NOP_EXPR)
        goto invalid_pointer_arithmetic;

      if (warn_assign_intercept)
        warning (0, "strong-cast assignment has been intercepted");

      result = objc_build_strong_cast_assignment (lhs, rhs);

      goto exit_point;
    }

  /* the lhs must be of a suitable type, regardless of its underlying
     structure.  */
  if (!objc_is_gcable_p (lhs))
    goto exit_point;

  outer = lhs;

  while (outer
         && (TREE_CODE (outer) == COMPONENT_REF
             || TREE_CODE (outer) == ARRAY_REF))
    outer = TREE_OPERAND (outer, 0);

  if (TREE_CODE (outer) == INDIRECT_REF)
    {
      outer = TREE_OPERAND (outer, 0);
      indirect_p = 1;
    }

  outer_gc_p = objc_is_gcable_p (outer);

  /* Handle ivar assignments. */
  if (objc_is_ivar_reference_p (lhs))
    {
      /* if the struct to the left of the ivar is not an Objective-C object (__strong
         doesn't cut it here), the best we can do here is suggest a cast.  */
      if (!objc_is_gcable_type (TREE_TYPE (outer), 0))
        {
          /* We may still be able to use the global write barrier... */
          if (!indirect_p && objc_is_global_reference_p (outer))
            goto global_reference;

         suggest_cast:
          if (modifycode == NOP_EXPR)
            {
              if (warn_assign_intercept)
                warning (0, "strong-cast may possibly be needed");
            }

          goto exit_point;
        }

      if (modifycode != NOP_EXPR)
        goto invalid_pointer_arithmetic;

      if (warn_assign_intercept)
        warning (0, "instance variable assignment has been intercepted");

      result = objc_build_ivar_assignment (outer, lhs, rhs);

      goto exit_point;
    }

  /* Likewise, intercept assignment to global/static variables if their type is
     GC-marked.  */
  if (objc_is_global_reference_p (outer))
    {
      if (indirect_p)
        goto suggest_cast;

     global_reference:
      if (modifycode != NOP_EXPR)
        {
         invalid_pointer_arithmetic:
          if (outer_gc_p)
            warning (0, "pointer arithmetic for garbage-collected objects not allowed");

          goto exit_point;
        }

      if (warn_assign_intercept)
        warning (0, "global/static variable assignment has been intercepted");

      result = objc_build_global_assignment (lhs, rhs);
    }

  /* In all other cases, fall back to the normal mechanism.  */
 exit_point:
  return result;
}

struct GTY(()) interface_tuple {
  tree id;
  tree class_name;
};

static GTY ((param_is (struct interface_tuple))) htab_t interface_htab;

static hashval_t
hash_interface (const void *p)
{
  const struct interface_tuple *d = (const struct interface_tuple *) p;
  return IDENTIFIER_HASH_VALUE (d->id);
}

static int
eq_interface (const void *p1, const void *p2)
{
  const struct interface_tuple *d = (const struct interface_tuple *) p1;
  return d->id == p2;
}

static tree
lookup_interface (tree ident)
{
#ifdef OBJCPLUS
  if (ident && TREE_CODE (ident) == TYPE_DECL)
    ident = DECL_NAME (ident);
#endif

  if (ident == NULL_TREE || TREE_CODE (ident) != IDENTIFIER_NODE)
    return NULL_TREE;

  {
    struct interface_tuple **slot;
    tree i = NULL_TREE;

    if (interface_htab)
      {
        slot = (struct interface_tuple **)
          htab_find_slot_with_hash (interface_htab, ident,
                                    IDENTIFIER_HASH_VALUE (ident),
                                    NO_INSERT);
        if (slot && *slot)
          i = (*slot)->class_name;
      }
    return i;
  }
}

/* Implement @defs (<classname>) within struct bodies.  */

tree
objc_get_class_ivars (tree class_name)
{
  tree interface = lookup_interface (class_name);

  if (interface)
    return get_class_ivars (interface, true);

  error ("cannot find interface declaration for %qE",
         class_name);

  return error_mark_node;
}

/* Called when checking the variables in a struct.  If we are not
   doing the ivars list inside an @interface context, then returns
   fieldlist unchanged.  Else, returns the list of class ivars.
*/
tree
objc_get_interface_ivars (tree fieldlist)
{
  if (!objc_collecting_ivars || !objc_interface_context 
      || TREE_CODE (objc_interface_context) != CLASS_INTERFACE_TYPE
      || CLASS_SUPER_NAME (objc_interface_context) == NULL_TREE)
    return fieldlist;

  return get_class_ivars (objc_interface_context, true);
}

/* Used by: build_private_template, continue_class,
   and for @defs constructs.  */

static tree
get_class_ivars (tree interface, bool inherited)
{
  tree ivar_chain = copy_list (CLASS_RAW_IVARS (interface));

  /* Both CLASS_RAW_IVARS and CLASS_IVARS contain a list of ivars declared
     by the current class (i.e., they do not include super-class ivars).
     However, the CLASS_IVARS list will be side-effected by a call to
     finish_struct(), which will fill in field offsets.  */
  if (!CLASS_IVARS (interface))
    CLASS_IVARS (interface) = ivar_chain;

  if (!inherited)
    return ivar_chain;

  while (CLASS_SUPER_NAME (interface))
    {
      /* Prepend super-class ivars.  */
      interface = lookup_interface (CLASS_SUPER_NAME (interface));
      ivar_chain = chainon (copy_list (CLASS_RAW_IVARS (interface)),
                            ivar_chain);
    }

  return ivar_chain;
}

\f
/* Exception handling constructs.  We begin by having the parser do most
   of the work and passing us blocks.  What we do next depends on whether
   we're doing "native" exception handling or legacy Darwin setjmp exceptions.
   We abstract all of this in a handful of appropriately named routines.  */

/* Stack of open try blocks.  */

struct objc_try_context
{
  struct objc_try_context *outer;

  /* Statements (or statement lists) as processed by the parser.  */
  tree try_body;
  tree finally_body;

  /* Some file position locations.  */
  location_t try_locus;
  location_t end_try_locus;
  location_t end_catch_locus;
  location_t finally_locus;
  location_t end_finally_locus;

  /* A STATEMENT_LIST of CATCH_EXPRs, appropriate for sticking into op1
     of a TRY_CATCH_EXPR.  Even when doing Darwin setjmp.  */
  tree catch_list;

  /* The CATCH_EXPR of an open @catch clause.  */
  tree current_catch;

  /* The VAR_DECL holding the Darwin equivalent of __builtin_eh_pointer.  */
  tree caught_decl;
  tree stack_decl;
  tree rethrow_decl;
};

static struct objc_try_context *cur_try_context;

static GTY(()) tree objc_eh_personality_decl;

/* This hook, called via lang_eh_runtime_type, generates a runtime object
   that represents TYPE.  For Objective-C, this is just the class name.  */
/* ??? Isn't there a class object or some such?  Is it easy to get?  */

#ifndef OBJCPLUS
tree
objc_eh_runtime_type (tree type)
{
  return add_objc_string (OBJC_TYPE_NAME (TREE_TYPE (type)), class_names);
}

tree
objc_eh_personality (void)
{
  if (!flag_objc_sjlj_exceptions && !objc_eh_personality_decl)
    objc_eh_personality_decl = build_personality_function ("gnu_objc");
  return objc_eh_personality_decl;
}
#endif

/* Build __builtin_eh_pointer, or the moral equivalent.  In the case
   of Darwin, we'll arrange for it to be initialized (and associated
   with a binding) later.  */

static tree
objc_build_exc_ptr (void)
{
  if (flag_objc_sjlj_exceptions)
    {
      tree var = cur_try_context->caught_decl;
      if (!var)
        {
          var = objc_create_temporary_var (objc_object_type, NULL);
          cur_try_context->caught_decl = var;
        }
      return var;
    }
  else
    {
      tree t;
      t = built_in_decls[BUILT_IN_EH_POINTER];
      t = build_call_expr (t, 1, integer_zero_node);
      return fold_convert (objc_object_type, t);
    }
}

/* Build "objc_exception_try_exit(&_stack)".  */

static tree
next_sjlj_build_try_exit (void)
{
  tree t;
  t = build_fold_addr_expr_loc (input_location, cur_try_context->stack_decl);
  t = tree_cons (NULL, t, NULL);
  t = build_function_call (input_location,
                           objc_exception_try_exit_decl, t);
  return t;
}

/* Build
        objc_exception_try_enter (&_stack);
        if (_setjmp(&_stack.buf))
          ;
        else
          ;
   Return the COND_EXPR.  Note that the THEN and ELSE fields are left
   empty, ready for the caller to fill them in.  */

static tree
next_sjlj_build_enter_and_setjmp (void)
{
  tree t, enter, sj, cond;

  t = build_fold_addr_expr_loc (input_location, cur_try_context->stack_decl);
  t = tree_cons (NULL, t, NULL);
  enter = build_function_call (input_location,
                               objc_exception_try_enter_decl, t);

  t = objc_build_component_ref (cur_try_context->stack_decl,
                                get_identifier ("buf"));
  t = build_fold_addr_expr_loc (input_location, t);
#ifdef OBJCPLUS
  /* Convert _setjmp argument to type that is expected.  */
  if (TYPE_ARG_TYPES (TREE_TYPE (objc_setjmp_decl)))
    t = convert (TREE_VALUE (TYPE_ARG_TYPES (TREE_TYPE (objc_setjmp_decl))), t);
  else
    t = convert (ptr_type_node, t);
#else
  t = convert (ptr_type_node, t);
#endif
  t = tree_cons (NULL, t, NULL);
  sj = build_function_call (input_location,
                            objc_setjmp_decl, t);

  cond = build2 (COMPOUND_EXPR, TREE_TYPE (sj), enter, sj);
  cond = c_common_truthvalue_conversion (input_location, cond);

  return build3 (COND_EXPR, void_type_node, cond, NULL, NULL);
}

/* Build:

   DECL = objc_exception_extract(&_stack);  */

static tree
next_sjlj_build_exc_extract (tree decl)
{
  tree t;

  t = build_fold_addr_expr_loc (input_location, cur_try_context->stack_decl);
  t = tree_cons (NULL, t, NULL);
  t = build_function_call (input_location,
                           objc_exception_extract_decl, t);
  t = convert (TREE_TYPE (decl), t);
  t = build2 (MODIFY_EXPR, void_type_node, decl, t);

  return t;
}

/* Build
        if (objc_exception_match(obj_get_class(TYPE), _caught)
          BODY
        else if (...)
          ...
        else
          {
            _rethrow = _caught;
            objc_exception_try_exit(&_stack);
          }
   from the sequence of CATCH_EXPRs in the current try context.  */

static tree
next_sjlj_build_catch_list (void)
{
  tree_stmt_iterator i = tsi_start (cur_try_context->catch_list);
  tree catch_seq, t;
  tree *last = &catch_seq;
  bool saw_id = false;

  for (; !tsi_end_p (i); tsi_next (&i))
    {
      tree stmt = tsi_stmt (i);
      tree type = CATCH_TYPES (stmt);
      tree body = CATCH_BODY (stmt);

      if (type == NULL)
        {
          *last = body;
          saw_id = true;
          break;
        }
      else
        {
          tree args, cond;

          if (type == error_mark_node)
            cond = error_mark_node;
          else
            {
              args = tree_cons (NULL, cur_try_context->caught_decl, NULL);
              t = objc_get_class_reference (OBJC_TYPE_NAME (TREE_TYPE (type)));
              args = tree_cons (NULL, t, args);
              t = build_function_call (input_location,
                                       objc_exception_match_decl, args);
              cond = c_common_truthvalue_conversion (input_location, t);
            }
          t = build3 (COND_EXPR, void_type_node, cond, body, NULL);
          SET_EXPR_LOCATION (t, EXPR_LOCATION (stmt));

          *last = t;
          last = &COND_EXPR_ELSE (t);
        }
    }

  if (!saw_id)
    {
      t = build2 (MODIFY_EXPR, void_type_node, cur_try_context->rethrow_decl,
                  cur_try_context->caught_decl);
      SET_EXPR_LOCATION (t, cur_try_context->end_catch_locus);
      append_to_statement_list (t, last);

      t = next_sjlj_build_try_exit ();
      SET_EXPR_LOCATION (t, cur_try_context->end_catch_locus);
      append_to_statement_list (t, last);
    }

  return catch_seq;
}

/* Build a complete @try-@catch-@finally block for legacy Darwin setjmp
   exception handling.  We aim to build:

        {
          struct _objc_exception_data _stack;
          id _rethrow = 0;
          try
            {
              objc_exception_try_enter (&_stack);
              if (_setjmp(&_stack.buf))
                {
                  id _caught = objc_exception_extract(&_stack);
                  objc_exception_try_enter (&_stack);
                  if (_setjmp(&_stack.buf))
                    _rethrow = objc_exception_extract(&_stack);
                  else
                    CATCH-LIST
                }
              else
                TRY-BLOCK
            }
          finally
            {
              if (!_rethrow)
                objc_exception_try_exit(&_stack);
              FINALLY-BLOCK
              if (_rethrow)
                objc_exception_throw(_rethrow);
            }
        }

   If CATCH-LIST is empty, we can omit all of the block containing
   "_caught" except for the setting of _rethrow.  Note the use of
   a real TRY_FINALLY_EXPR here, which is not involved in EH per-se,
   but handles goto and other exits from the block.  */

static tree
next_sjlj_build_try_catch_finally (void)
{
  tree rethrow_decl, stack_decl, t;
  tree catch_seq, try_fin, bind;

  /* Create the declarations involved.  */
  t = xref_tag (RECORD_TYPE, get_identifier (UTAG_EXCDATA));
  stack_decl = objc_create_temporary_var (t, NULL);
  cur_try_context->stack_decl = stack_decl;

  rethrow_decl = objc_create_temporary_var (objc_object_type, NULL);
  cur_try_context->rethrow_decl = rethrow_decl;
  TREE_CHAIN (rethrow_decl) = stack_decl;

  /* Build the outermost variable binding level.  */
  bind = build3 (BIND_EXPR, void_type_node, rethrow_decl, NULL, NULL);
  SET_EXPR_LOCATION (bind, cur_try_context->try_locus);
  TREE_SIDE_EFFECTS (bind) = 1;

  /* Initialize rethrow_decl.  */
  t = build2 (MODIFY_EXPR, void_type_node, rethrow_decl,
              convert (objc_object_type, null_pointer_node));
  SET_EXPR_LOCATION (t, cur_try_context->try_locus);
  append_to_statement_list (t, &BIND_EXPR_BODY (bind));

  /* Build the outermost TRY_FINALLY_EXPR.  */
  try_fin = build2 (TRY_FINALLY_EXPR, void_type_node, NULL, NULL);
  SET_EXPR_LOCATION (try_fin, cur_try_context->try_locus);
  TREE_SIDE_EFFECTS (try_fin) = 1;
  append_to_statement_list (try_fin, &BIND_EXPR_BODY (bind));

  /* Create the complete catch sequence.  */
  if (cur_try_context->catch_list)
    {
      tree caught_decl = objc_build_exc_ptr ();
      catch_seq = build_stmt (input_location, BIND_EXPR, caught_decl, NULL, NULL);
      TREE_SIDE_EFFECTS (catch_seq) = 1;

      t = next_sjlj_build_exc_extract (caught_decl);
      append_to_statement_list (t, &BIND_EXPR_BODY (catch_seq));

      t = next_sjlj_build_enter_and_setjmp ();
      COND_EXPR_THEN (t) = next_sjlj_build_exc_extract (rethrow_decl);
      COND_EXPR_ELSE (t) = next_sjlj_build_catch_list ();
      append_to_statement_list (t, &BIND_EXPR_BODY (catch_seq));
    }
  else
    catch_seq = next_sjlj_build_exc_extract (rethrow_decl);
  SET_EXPR_LOCATION (catch_seq, cur_try_context->end_try_locus);

  /* Build the main register-and-try if statement.  */
  t = next_sjlj_build_enter_and_setjmp ();
  SET_EXPR_LOCATION (t, cur_try_context->try_locus);
  COND_EXPR_THEN (t) = catch_seq;
  COND_EXPR_ELSE (t) = cur_try_context->try_body;
  TREE_OPERAND (try_fin, 0) = t;

  /* Build the complete FINALLY statement list.  */
  t = next_sjlj_build_try_exit ();
  t = build_stmt (input_location, COND_EXPR,
                  c_common_truthvalue_conversion 
                    (input_location, rethrow_decl),
                  NULL, t);
  SET_EXPR_LOCATION (t, cur_try_context->finally_locus);
  append_to_statement_list (t, &TREE_OPERAND (try_fin, 1));

  append_to_statement_list (cur_try_context->finally_body,
                            &TREE_OPERAND (try_fin, 1));

  t = tree_cons (NULL, rethrow_decl, NULL);
  t = build_function_call (input_location,
                           objc_exception_throw_decl, t);
  t = build_stmt (input_location, COND_EXPR,
                  c_common_truthvalue_conversion (input_location, 
                                                  rethrow_decl),
                  t, NULL);
  SET_EXPR_LOCATION (t, cur_try_context->end_finally_locus);
  append_to_statement_list (t, &TREE_OPERAND (try_fin, 1));

  return bind;
}

/* Called just after parsing the @try and its associated BODY.  We now
   must prepare for the tricky bits -- handling the catches and finally.  */

void
objc_begin_try_stmt (location_t try_locus, tree body)
{
  struct objc_try_context *c = XCNEW (struct objc_try_context);
  c->outer = cur_try_context;
  c->try_body = body;
  c->try_locus = try_locus;
  c->end_try_locus = input_location;
  cur_try_context = c;

  /* -fobjc-exceptions is required to enable Objective-C exceptions.
     For example, on Darwin, ObjC exceptions require a sufficiently
     recent version of the runtime, so the user must ask for them
     explicitly.  On other platforms, at the moment -fobjc-exceptions
     triggers -fexceptions which again is required for exceptions to
     work.
  */
  if (!flag_objc_exceptions)
    {
      error_at (try_locus, "%<-fobjc-exceptions%> is required to enable Objective-C exception syntax");
    }

  if (flag_objc_sjlj_exceptions)
    objc_mark_locals_volatile (NULL);
}

/* Called just after parsing "@catch (parm)".  Open a binding level,
   enter DECL into the binding level, and initialize it.  Leave the
   binding level open while the body of the compound statement is parsed.  */

void
objc_begin_catch_clause (tree decl)
{
  tree compound, type, t;

  /* Begin a new scope that the entire catch clause will live in.  */
  compound = c_begin_compound_stmt (true);

  /* The parser passed in a PARM_DECL, but what we really want is a VAR_DECL.  */
  decl = build_decl (input_location,
                     VAR_DECL, DECL_NAME (decl), TREE_TYPE (decl));
  lang_hooks.decls.pushdecl (decl);

  /* Since a decl is required here by syntax, don't warn if its unused.  */
  /* ??? As opposed to __attribute__((unused))?  Anyway, this appears to
     be what the previous objc implementation did.  */
  TREE_USED (decl) = 1;
  DECL_READ_P (decl) = 1;

  /* Verify that the type of the catch is valid.  It must be a pointer
     to an Objective-C class, or "id" (which is catch-all).  */
  type = TREE_TYPE (decl);

  if (POINTER_TYPE_P (type) && objc_is_object_id (TREE_TYPE (type)))
    type = NULL;
  else if (!POINTER_TYPE_P (type) || !TYPED_OBJECT (TREE_TYPE (type)))
    {
      error ("@catch parameter is not a known Objective-C class type");
      type = error_mark_node;
    }
  else if (cur_try_context->catch_list)
    {
      /* Examine previous @catch clauses and see if we've already
         caught the type in question.  */
      tree_stmt_iterator i = tsi_start (cur_try_context->catch_list);
      for (; !tsi_end_p (i); tsi_next (&i))
        {
          tree stmt = tsi_stmt (i);
          t = CATCH_TYPES (stmt);
          if (t == error_mark_node)
            continue;
          if (!t || DERIVED_FROM_P (TREE_TYPE (t), TREE_TYPE (type)))
            {
              warning (0, "exception of type %<%T%> will be caught",
                       TREE_TYPE (type));
              warning_at  (EXPR_LOCATION (stmt), 0, "   by earlier handler for %<%T%>",
                           TREE_TYPE (t ? t : objc_object_type));
              break;
            }
        }
    }

  /* Record the data for the catch in the try context so that we can
     finalize it later.  */
  t = build_stmt (input_location, CATCH_EXPR, type, compound);
  cur_try_context->current_catch = t;

  /* Initialize the decl from the EXC_PTR_EXPR we get from the runtime.  */
  t = objc_build_exc_ptr ();
  t = convert (TREE_TYPE (decl), t);
  t = build2 (MODIFY_EXPR, void_type_node, decl, t);
  add_stmt (t);
}

/* Called just after parsing the closing brace of a @catch clause.  Close
   the open binding level, and record a CATCH_EXPR for it.  */

void
objc_finish_catch_clause (void)
{
  tree c = cur_try_context->current_catch;
  cur_try_context->current_catch = NULL;
  cur_try_context->end_catch_locus = input_location;

  CATCH_BODY (c) = c_end_compound_stmt (input_location, CATCH_BODY (c), 1);
  append_to_statement_list (c, &cur_try_context->catch_list);
}

/* Called after parsing a @finally clause and its associated BODY.
   Record the body for later placement.  */

void
objc_build_finally_clause (location_t finally_locus, tree body)
{
  cur_try_context->finally_body = body;
  cur_try_context->finally_locus = finally_locus;
  cur_try_context->end_finally_locus = input_location;
}

/* Called to finalize a @try construct.  */

tree
objc_finish_try_stmt (void)
{
  struct objc_try_context *c = cur_try_context;
  tree stmt;

  if (c->catch_list == NULL && c->finally_body == NULL)
    error ("%<@try%> without %<@catch%> or %<@finally%>");

  /* If we're doing Darwin setjmp exceptions, build the big nasty.  */
  if (flag_objc_sjlj_exceptions)
    {
      bool save = in_late_binary_op;
      in_late_binary_op = true;
      if (!cur_try_context->finally_body)
        {
          cur_try_context->finally_locus = input_location;
          cur_try_context->end_finally_locus = input_location;
        }
      stmt = next_sjlj_build_try_catch_finally ();
      in_late_binary_op = save;
    }
  else
    {
      /* Otherwise, nest the CATCH inside a FINALLY.  */
      stmt = c->try_body;
      if (c->catch_list)
        {
          stmt = build_stmt (input_location, TRY_CATCH_EXPR, stmt, c->catch_list);
          SET_EXPR_LOCATION (stmt, cur_try_context->try_locus);
        }
      if (c->finally_body)
        {
          stmt = build_stmt (input_location, TRY_FINALLY_EXPR, stmt, c->finally_body);
          SET_EXPR_LOCATION (stmt, cur_try_context->try_locus);
        }
    }
  add_stmt (stmt);

  cur_try_context = c->outer;
  free (c);
  return stmt;
}

tree
objc_build_throw_stmt (location_t loc, tree throw_expr)
{
  tree args;

  if (!flag_objc_exceptions)
    {
      error_at (loc, "%<-fobjc-exceptions%> is required to enable Objective-C exception syntax");
    }

  if (throw_expr == NULL)
    {
      /* If we're not inside a @catch block, there is no "current
         exception" to be rethrown.  */
      if (cur_try_context == NULL
          || cur_try_context->current_catch == NULL)
        {
          error_at (loc, "%<@throw%> (rethrow) used outside of a @catch block");
          return NULL_TREE;
        }

      /* Otherwise the object is still sitting in the EXC_PTR_EXPR
         value that we get from the runtime.  */
      throw_expr = objc_build_exc_ptr ();
    }

  /* A throw is just a call to the runtime throw function with the
     object as a parameter.  */
  args = tree_cons (NULL, throw_expr, NULL);
  return add_stmt (build_function_call (loc,
                                        objc_exception_throw_decl, args));
}

tree
objc_build_synchronized (location_t start_locus, tree mutex, tree body)
{
  tree args, call;

  /* First lock the mutex.  */
  mutex = save_expr (mutex);
  args = tree_cons (NULL, mutex, NULL);
  call = build_function_call (input_location,
                              objc_sync_enter_decl, args);
  SET_EXPR_LOCATION (call, start_locus);
  add_stmt (call);

  /* Build the mutex unlock.  */
  args = tree_cons (NULL, mutex, NULL);
  call = build_function_call (input_location,
                              objc_sync_exit_decl, args);
  SET_EXPR_LOCATION (call, input_location);

  /* Put the that and the body in a TRY_FINALLY.  */
  objc_begin_try_stmt (start_locus, body);
  objc_build_finally_clause (input_location, call);
  return objc_finish_try_stmt ();
}

\f
/* Predefine the following data type:

   struct _objc_exception_data
   {
     int buf[OBJC_JBLEN];
     void *pointers[4];
   }; */

/* The following yuckiness should prevent users from having to #include
   <setjmp.h> in their code... */

/* Define to a harmless positive value so the below code doesn't die.  */
#ifndef OBJC_JBLEN
#define OBJC_JBLEN 18
#endif

static void
build_next_objc_exception_stuff (void)
{
  tree decls, temp_type, *chain = NULL;

  objc_exception_data_template
    = objc_start_struct (get_identifier (UTAG_EXCDATA));

  /* int buf[OBJC_JBLEN]; */

  temp_type = build_sized_array_type (integer_type_node, OBJC_JBLEN);
  decls = add_field_decl (temp_type, "buf", &chain);

  /* void *pointers[4]; */

  temp_type = build_sized_array_type (ptr_type_node, 4);
  add_field_decl (temp_type, "pointers", &chain);

  objc_finish_struct (objc_exception_data_template, decls);

  /* int _setjmp(...); */
  /* If the user includes <setjmp.h>, this shall be superseded by
     'int _setjmp(jmp_buf);' */
  temp_type = build_varargs_function_type_list (integer_type_node, NULL_TREE);
  objc_setjmp_decl
    = add_builtin_function (TAG_SETJMP, temp_type, 0, NOT_BUILT_IN, NULL, NULL_TREE);

  /* id objc_exception_extract(struct _objc_exception_data *); */
  temp_type
    = build_function_type_list (objc_object_type,
                                build_pointer_type (objc_exception_data_template),
                                NULL_TREE);
  objc_exception_extract_decl
    = add_builtin_function (TAG_EXCEPTIONEXTRACT, temp_type, 0, NOT_BUILT_IN, NULL,
                            NULL_TREE);
  /* void objc_exception_try_enter(struct _objc_exception_data *); */
  /* void objc_exception_try_exit(struct _objc_exception_data *); */
  temp_type
    = build_function_type_list (void_type_node,
                                build_pointer_type (objc_exception_data_template),
                                NULL_TREE);
  objc_exception_try_enter_decl
    = add_builtin_function (TAG_EXCEPTIONTRYENTER, temp_type, 0, NOT_BUILT_IN, NULL,
                            NULL_TREE);
  objc_exception_try_exit_decl
    = add_builtin_function (TAG_EXCEPTIONTRYEXIT, temp_type, 0, NOT_BUILT_IN, NULL,
                            NULL_TREE);

  /* int objc_exception_match(id, id); */
  temp_type
    = build_function_type_list (integer_type_node,
                                objc_object_type, objc_object_type, NULL_TREE);
  objc_exception_match_decl
    = add_builtin_function (TAG_EXCEPTIONMATCH, temp_type, 0, NOT_BUILT_IN, NULL,
                            NULL_TREE);

  /* id objc_assign_ivar (id, id, unsigned int); */
  /* id objc_assign_ivar_Fast (id, id, unsigned int)
       __attribute__ ((hard_coded_address (OFFS_ASSIGNIVAR_FAST))); */
  temp_type
    = build_function_type_list (objc_object_type,
                                objc_object_type,
                                objc_object_type,
                                unsigned_type_node,
                                NULL_TREE);
  objc_assign_ivar_decl
    = add_builtin_function (TAG_ASSIGNIVAR, temp_type, 0, NOT_BUILT_IN,
                            NULL, NULL_TREE);
#ifdef OFFS_ASSIGNIVAR_FAST
  objc_assign_ivar_fast_decl
    = add_builtin_function (TAG_ASSIGNIVAR_FAST, temp_type, 0,
                            NOT_BUILT_IN, NULL, NULL_TREE);
  DECL_ATTRIBUTES (objc_assign_ivar_fast_decl)
    = tree_cons (get_identifier ("hard_coded_address"),
                 build_int_cst (NULL_TREE, OFFS_ASSIGNIVAR_FAST),
                 NULL_TREE);
#else
  /* Default to slower ivar method.  */
  objc_assign_ivar_fast_decl = objc_assign_ivar_decl;
#endif

  /* id objc_assign_global (id, id *); */
  /* id objc_assign_strongCast (id, id *); */
  temp_type = build_function_type_list (objc_object_type,
                                        objc_object_type,
                                        build_pointer_type (objc_object_type),
                                        NULL_TREE);
  objc_assign_global_decl
        = add_builtin_function (TAG_ASSIGNGLOBAL, temp_type, 0, NOT_BUILT_IN, NULL,
                                NULL_TREE);
  objc_assign_strong_cast_decl
        = add_builtin_function (TAG_ASSIGNSTRONGCAST, temp_type, 0, NOT_BUILT_IN, NULL,
                                NULL_TREE);
}

static void
build_objc_exception_stuff (void)
{
  tree noreturn_list, nothrow_list, temp_type;

  noreturn_list = tree_cons (get_identifier ("noreturn"), NULL, NULL);
  nothrow_list = tree_cons (get_identifier ("nothrow"), NULL, NULL);

  /* void objc_exception_throw(id) __attribute__((noreturn)); */
  /* void objc_sync_enter(id); */
  /* void objc_sync_exit(id); */
  temp_type = build_function_type_list (void_type_node,
                                        objc_object_type,
                                        NULL_TREE);
  objc_exception_throw_decl
    = add_builtin_function (TAG_EXCEPTIONTHROW, temp_type, 0, NOT_BUILT_IN, NULL,
                            noreturn_list);
  objc_sync_enter_decl
    = add_builtin_function (TAG_SYNCENTER, temp_type, 0, NOT_BUILT_IN,
                            NULL, nothrow_list);
  objc_sync_exit_decl
    = add_builtin_function (TAG_SYNCEXIT, temp_type, 0, NOT_BUILT_IN,
                            NULL, nothrow_list);
}

/* Construct a C struct corresponding to ObjC class CLASS, with the same
   name as the class:

   struct <classname> {
     struct _objc_class *isa;
     ...
   };  */

static void
build_private_template (tree klass)
{
  if (!CLASS_STATIC_TEMPLATE (klass))
    {
      tree record = objc_build_struct (klass,
                                       get_class_ivars (klass, false),
                                       CLASS_SUPER_NAME (klass));

      /* Set the TREE_USED bit for this struct, so that stab generator
         can emit stabs for this struct type.  */
      if (flag_debug_only_used_symbols && TYPE_STUB_DECL (record))
        TREE_USED (TYPE_STUB_DECL (record)) = 1;
    }
}
\f
/* Begin code generation for protocols...  */

/* struct _objc_protocol {
     struct _objc_class *isa;
     char *protocol_name;
     struct _objc_protocol **protocol_list;
     struct _objc__method_prototype_list *instance_methods;
     struct _objc__method_prototype_list *class_methods;
   };  */

static void
build_protocol_template (void)
{
  tree ptype, decls, *chain = NULL;

  objc_protocol_template = objc_start_struct (get_identifier (UTAG_PROTOCOL));

  /* struct _objc_class *isa; */
  ptype = build_pointer_type (xref_tag (RECORD_TYPE,
                                        get_identifier (UTAG_CLASS)));
  decls = add_field_decl (ptype, "isa", &chain);

  /* char *protocol_name; */
  add_field_decl (string_type_node, "protocol_name", &chain);

  /* struct _objc_protocol **protocol_list; */
  ptype = build_pointer_type (build_pointer_type (objc_protocol_template));
  add_field_decl (ptype, "protocol_list", &chain);

  /* struct _objc__method_prototype_list *instance_methods; */
  add_field_decl (objc_method_proto_list_ptr, "instance_methods", &chain);

  /* struct _objc__method_prototype_list *class_methods; */
  add_field_decl (objc_method_proto_list_ptr, "class_methods", &chain);

  objc_finish_struct (objc_protocol_template, decls);
}

static tree
build_descriptor_table_initializer (tree type, tree entries)
{
  VEC(constructor_elt,gc) *inits = NULL;

  do
    {
      VEC(constructor_elt,gc) *elts = NULL;

      CONSTRUCTOR_APPEND_ELT (elts, NULL_TREE,
                              build_selector (METHOD_SEL_NAME (entries)));
      CONSTRUCTOR_APPEND_ELT (elts, NULL_TREE,
                              add_objc_string (METHOD_ENCODING (entries),
                                               meth_var_types));

      CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE,
                              objc_build_constructor (type, elts));

      entries = DECL_CHAIN (entries);
    }
  while (entries);

  return objc_build_constructor (build_array_type (type, 0), inits);
}

/* struct objc_method_prototype_list {
     int count;
     struct objc_method_prototype {
        SEL name;
        char *types;
     } list[1];
   };  */

static tree
build_method_prototype_list_template (tree list_type, int size)
{
  tree objc_ivar_list_record;
  tree array_type, decls, *chain = NULL;

  /* Generate an unnamed struct definition.  */

  objc_ivar_list_record = objc_start_struct (NULL_TREE);

  /* int method_count; */
  decls = add_field_decl (integer_type_node, "method_count", &chain);

  /* struct objc_method method_list[]; */
  array_type = build_sized_array_type (list_type, size);
  add_field_decl (array_type, "method_list", &chain);

  objc_finish_struct (objc_ivar_list_record, decls);

  return objc_ivar_list_record;
}

static tree
build_method_prototype_template (void)
{
  tree proto_record;
  tree decls, *chain = NULL;

  proto_record = objc_start_struct (get_identifier (UTAG_METHOD_PROTOTYPE));

  /* SEL _cmd; */
  decls = add_field_decl (objc_selector_type, "_cmd", &chain);

  /* char *method_types; */
  add_field_decl (string_type_node, "method_types", &chain);

  objc_finish_struct (proto_record, decls);

  return proto_record;
}

static tree
objc_method_parm_type (tree type)
{
  type = TREE_VALUE (TREE_TYPE (type));
  if (TREE_CODE (type) == TYPE_DECL)
    type = TREE_TYPE (type);
  return type;
}

static int
objc_encoded_type_size (tree type)
{
  int sz = int_size_in_bytes (type);

  /* Make all integer and enum types at least as large
     as an int.  */
  if (sz > 0 && INTEGRAL_TYPE_P (type))
    sz = MAX (sz, int_size_in_bytes (integer_type_node));
  /* Treat arrays as pointers, since that's how they're
     passed in.  */
  else if (TREE_CODE (type) == ARRAY_TYPE)
    sz = int_size_in_bytes (ptr_type_node);
  return sz;
}

/* Encode a method prototype.

   The format is described in gcc/doc/objc.texi, section 'Method
   signatures'.
 */
static tree
encode_method_prototype (tree method_decl)
{
  tree parms;
  int parm_offset, i;
  char buf[40];
  tree result;

  /* ONEWAY and BYCOPY, for remote object are the only method qualifiers.  */
  encode_type_qualifiers (TREE_PURPOSE (TREE_TYPE (method_decl)));

  /* Encode return type.  */
  encode_type (objc_method_parm_type (method_decl),
               obstack_object_size (&util_obstack),
               OBJC_ENCODE_INLINE_DEFS);

  /* Stack size.  */
  /* The first two arguments (self and _cmd) are pointers; account for
     their size.  */
  i = int_size_in_bytes (ptr_type_node);
  parm_offset = 2 * i;
  for (parms = METHOD_SEL_ARGS (method_decl); parms;
       parms = DECL_CHAIN (parms))
    {
      tree type = objc_method_parm_type (parms);
      int sz = objc_encoded_type_size (type);

      /* If a type size is not known, bail out.  */
      if (sz < 0)
        {
          error ("type %q+D does not have a known size",
                 type);
          /* Pretend that the encoding succeeded; the compilation will
             fail nevertheless.  */
          goto finish_encoding;
        }
      parm_offset += sz;
    }

  sprintf (buf, "%d@0:%d", parm_offset, i);
  obstack_grow (&util_obstack, buf, strlen (buf));

  /* Argument types.  */
  parm_offset = 2 * i;
  for (parms = METHOD_SEL_ARGS (method_decl); parms;
       parms = DECL_CHAIN (parms))
    {
      tree type = objc_method_parm_type (parms);

      /* Process argument qualifiers for user supplied arguments.  */
      encode_type_qualifiers (TREE_PURPOSE (TREE_TYPE (parms)));

      /* Type.  */
      encode_type (type, obstack_object_size (&util_obstack),
                   OBJC_ENCODE_INLINE_DEFS);

      /* Compute offset.  */
      sprintf (buf, "%d", parm_offset);
      parm_offset += objc_encoded_type_size (type);

      obstack_grow (&util_obstack, buf, strlen (buf));
    }

  finish_encoding:
  obstack_1grow (&util_obstack, '\0');
  result = get_identifier (XOBFINISH (&util_obstack, char *));
  obstack_free (&util_obstack, util_firstobj);
  return result;
}

static tree
generate_descriptor_table (tree type, const char *name, int size, tree list,
                           tree proto)
{
  tree decl;
  VEC(constructor_elt,gc) *v = NULL;

  decl = start_var_decl (type, synth_id_with_class_suffix (name, proto));

  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, size));
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, list);

  finish_var_decl (decl, objc_build_constructor (type, v));

  return decl;
}

static void
generate_method_descriptors (tree protocol)
{
  tree initlist, chain, method_list_template;
  int size;

  if (!objc_method_prototype_template)
    objc_method_prototype_template = build_method_prototype_template ();

  chain = PROTOCOL_CLS_METHODS (protocol);
  if (chain)
    {
      size = list_length (chain);

      method_list_template
        = build_method_prototype_list_template (objc_method_prototype_template,
                                                size);

      initlist
        = build_descriptor_table_initializer (objc_method_prototype_template,
                                              chain);

      UOBJC_CLASS_METHODS_decl
        = generate_descriptor_table (method_list_template,
                                     "_OBJC_PROTOCOL_CLASS_METHODS",
                                     size, initlist, protocol);
    }
  else
    UOBJC_CLASS_METHODS_decl = 0;

  chain = PROTOCOL_NST_METHODS (protocol);
  if (chain)
    {
      size = list_length (chain);

      method_list_template
        = build_method_prototype_list_template (objc_method_prototype_template,
                                                size);
      initlist
        = build_descriptor_table_initializer (objc_method_prototype_template,
                                              chain);

      UOBJC_INSTANCE_METHODS_decl
        = generate_descriptor_table (method_list_template,
                                     "_OBJC_PROTOCOL_INSTANCE_METHODS",
                                     size, initlist, protocol);
    }
  else
    UOBJC_INSTANCE_METHODS_decl = 0;
}

static void
generate_protocol_references (tree plist)
{
  tree lproto;

  /* Forward declare protocols referenced.  */
  for (lproto = plist; lproto; lproto = TREE_CHAIN (lproto))
    {
      tree proto = TREE_VALUE (lproto);

      if (TREE_CODE (proto) == PROTOCOL_INTERFACE_TYPE
          && PROTOCOL_NAME (proto))
        {
          if (! PROTOCOL_FORWARD_DECL (proto))
            build_protocol_reference (proto);

          if (PROTOCOL_LIST (proto))
            generate_protocol_references (PROTOCOL_LIST (proto));
        }
    }
}

/* Generate either '- .cxx_construct' or '- .cxx_destruct' for the
   current class.  */
#ifdef OBJCPLUS
static void
objc_generate_cxx_ctor_or_dtor (bool dtor)
{
  tree fn, body, compound_stmt, ivar;

  /* - (id) .cxx_construct { ... return self; } */
  /* - (void) .cxx_construct { ... }            */

  objc_start_method_definition
    (false /* is_class_method */,
     objc_build_method_signature (false /* is_class_method */,
                                  build_tree_list (NULL_TREE,
                                                   dtor
                                                   ? void_type_node
                                                   : objc_object_type),
                                  get_identifier (dtor
                                                  ? TAG_CXX_DESTRUCT
                                                  : TAG_CXX_CONSTRUCT),
                                  make_node (TREE_LIST),
                                  false), NULL);
  body = begin_function_body ();
  compound_stmt = begin_compound_stmt (0);

  ivar = CLASS_IVARS (implementation_template);
  /* Destroy ivars in reverse order.  */
  if (dtor)
    ivar = nreverse (copy_list (ivar));

  for (; ivar; ivar = TREE_CHAIN (ivar))
    {
      if (TREE_CODE (ivar) == FIELD_DECL)
        {
          tree type = TREE_TYPE (ivar);

          /* Call the ivar's default constructor or destructor.  Do not
             call the destructor unless a corresponding constructor call
             has also been made (or is not needed).  */
          if (MAYBE_CLASS_TYPE_P (type)
              && (dtor
                  ? (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
                     && (!TYPE_NEEDS_CONSTRUCTING (type)
                         || TYPE_HAS_DEFAULT_CONSTRUCTOR (type)))
                  : (TYPE_NEEDS_CONSTRUCTING (type)
                     && TYPE_HAS_DEFAULT_CONSTRUCTOR (type))))
            finish_expr_stmt
             (build_special_member_call
              (build_ivar_reference (DECL_NAME (ivar)),
               dtor ? complete_dtor_identifier : complete_ctor_identifier,
               NULL, type, LOOKUP_NORMAL, tf_warning_or_error));
        }
    }

  /* The constructor returns 'self'.  */
  if (!dtor)
    finish_return_stmt (self_decl);

  finish_compound_stmt (compound_stmt);
  finish_function_body (body);
  fn = current_function_decl;
  finish_function ();
  objc_finish_method_definition (fn);
}

/* The following routine will examine the current @interface for any
   non-POD C++ ivars requiring non-trivial construction and/or
   destruction, and then synthesize special '- .cxx_construct' and/or
   '- .cxx_destruct' methods which will run the appropriate
   construction or destruction code.  Note that ivars inherited from
   super-classes are _not_ considered.  */
static void
objc_generate_cxx_cdtors (void)
{
  bool need_ctor = false, need_dtor = false;
  tree ivar;

  /* Error case, due to possibly an extra @end. */
  if (!objc_implementation_context)
    return;

  /* We do not want to do this for categories, since they do not have
     their own ivars.  */

  if (TREE_CODE (objc_implementation_context) != CLASS_IMPLEMENTATION_TYPE)
    return;

  /* First, determine if we even need a constructor and/or destructor.  */

  for (ivar = CLASS_IVARS (implementation_template); ivar;
       ivar = TREE_CHAIN (ivar))
    {
      if (TREE_CODE (ivar) == FIELD_DECL)
        {
          tree type = TREE_TYPE (ivar);

          if (MAYBE_CLASS_TYPE_P (type))
            {
              if (TYPE_NEEDS_CONSTRUCTING (type)
                  && TYPE_HAS_DEFAULT_CONSTRUCTOR (type))
                /* NB: If a default constructor is not available, we will not
                   be able to initialize this ivar; the add_instance_variable()
                   routine will already have warned about this.  */
                need_ctor = true;

              if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
                  && (!TYPE_NEEDS_CONSTRUCTING (type)
                      || TYPE_HAS_DEFAULT_CONSTRUCTOR (type)))
                /* NB: If a default constructor is not available, we will not
                   call the destructor either, for symmetry.  */
                need_dtor = true;
            }
        }
    }

  /* Generate '- .cxx_construct' if needed.  */

  if (need_ctor)
    objc_generate_cxx_ctor_or_dtor (false);

  /* Generate '- .cxx_destruct' if needed.  */

  if (need_dtor)
    objc_generate_cxx_ctor_or_dtor (true);

  /* The 'imp_list' variable points at an imp_entry record for the current
     @implementation.  Record the existence of '- .cxx_construct' and/or
     '- .cxx_destruct' methods therein; it will be included in the
     metadata for the class.  */
  if (flag_next_runtime)
    imp_list->has_cxx_cdtors = (need_ctor || need_dtor);
}
#endif

/* For each protocol which was referenced either from a @protocol()
   expression, or because a class/category implements it (then a
   pointer to the protocol is stored in the struct describing the
   class/category), we create a statically allocated instance of the
   Protocol class.  The code is written in such a way as to generate
   as few Protocol objects as possible; we generate a unique Protocol
   instance for each protocol, and we don't generate a Protocol
   instance if the protocol is never referenced (either from a
   @protocol() or from a class/category implementation).  These
   statically allocated objects can be referred to via the static
   (that is, private to this module) symbols _OBJC_PROTOCOL_n.

   The statically allocated Protocol objects that we generate here
   need to be fixed up at runtime in order to be used: the 'isa'
   pointer of the objects need to be set up to point to the 'Protocol'
   class, as known at runtime.

   The NeXT runtime fixes up all protocols at program startup time,
   before main() is entered.  It uses a low-level trick to look up all
   those symbols, then loops on them and fixes them up.

   The GNU runtime as well fixes up all protocols before user code
   from the module is executed; it requires pointers to those symbols
   to be put in the objc_symtab (which is then passed as argument to
   the function __objc_exec_class() which the compiler sets up to be
   executed automatically when the module is loaded); setup of those
   Protocol objects happen in two ways in the GNU runtime: all
   Protocol objects referred to by a class or category implementation
   are fixed up when the class/category is loaded; all Protocol
   objects referred to by a @protocol() expression are added by the
   compiler to the list of statically allocated instances to fixup
   (the same list holding the statically allocated constant string
   objects).  Because, as explained above, the compiler generates as
   few Protocol objects as possible, some Protocol object might end up
   being referenced multiple times when compiled with the GNU runtime,
   and end up being fixed up multiple times at runtime initialization.
   But that doesn't hurt, it's just a little inefficient.  */

static void
generate_protocols (void)
{
  tree p, encoding;
  tree decl;
  tree initlist, protocol_name_expr, refs_decl, refs_expr;

  /* If a protocol was directly referenced, pull in indirect references.  */
  for (p = protocol_chain; p; p = TREE_CHAIN (p))
    if (PROTOCOL_FORWARD_DECL (p) && PROTOCOL_LIST (p))
      generate_protocol_references (PROTOCOL_LIST (p));

  for (p = protocol_chain; p; p = TREE_CHAIN (p))
    {
      tree nst_methods = PROTOCOL_NST_METHODS (p);
      tree cls_methods = PROTOCOL_CLS_METHODS (p);

      /* If protocol wasn't referenced, don't generate any code.  */
      decl = PROTOCOL_FORWARD_DECL (p);

      if (!decl)
        continue;

      /* Make sure we link in the Protocol class.  */
      add_class_reference (get_identifier (PROTOCOL_OBJECT_CLASS_NAME));

      while (nst_methods)
        {
          if (! METHOD_ENCODING (nst_methods))
            {
              encoding = encode_method_prototype (nst_methods);
              METHOD_ENCODING (nst_methods) = encoding;
            }
          nst_methods = DECL_CHAIN (nst_methods);
        }

      while (cls_methods)
        {
          if (! METHOD_ENCODING (cls_methods))
            {
              encoding = encode_method_prototype (cls_methods);
              METHOD_ENCODING (cls_methods) = encoding;
            }

          cls_methods = DECL_CHAIN (cls_methods);
        }
      generate_method_descriptors (p);

      if (PROTOCOL_LIST (p))
        refs_decl = generate_protocol_list (p);
      else
        refs_decl = 0;

      /* static struct objc_protocol _OBJC_PROTOCOL_<mumble>; */
      protocol_name_expr = add_objc_string (PROTOCOL_NAME (p), class_names);

      if (refs_decl)
        refs_expr = convert (build_pointer_type (build_pointer_type
                                                 (objc_protocol_template)),
                             build_unary_op (input_location,
                                             ADDR_EXPR, refs_decl, 0));
      else
        refs_expr = build_int_cst (NULL_TREE, 0);

      /* UOBJC_INSTANCE_METHODS_decl/UOBJC_CLASS_METHODS_decl are set
         by generate_method_descriptors, which is called above.  */
      initlist = build_protocol_initializer (TREE_TYPE (decl),
                                             protocol_name_expr, refs_expr,
                                             UOBJC_INSTANCE_METHODS_decl,
                                             UOBJC_CLASS_METHODS_decl);
      finish_var_decl (decl, initlist);
    }
}

static tree
build_protocol_initializer (tree type, tree protocol_name,
                            tree protocol_list, tree instance_methods,
                            tree class_methods)
{
  tree expr;
  tree cast_type = build_pointer_type
                   (xref_tag (RECORD_TYPE,
                              get_identifier (UTAG_CLASS)));
  VEC(constructor_elt,gc) *inits = NULL;

  /* Filling the "isa" in with one allows the runtime system to
     detect that the version change...should remove before final release.  */

  expr = build_int_cst (cast_type, PROTOCOL_VERSION);
  CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, expr);
  CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, protocol_name);
  CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, protocol_list);

  if (!instance_methods)
    CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      expr = convert (objc_method_proto_list_ptr,
                      build_unary_op (input_location, 
                                      ADDR_EXPR, instance_methods, 0));
      CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, expr);
    }

  if (!class_methods)
    CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      expr = convert (objc_method_proto_list_ptr,
                      build_unary_op (input_location, 
                                      ADDR_EXPR, class_methods, 0));
      CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, expr);
    }

  return objc_build_constructor (type, inits);
}
\f
/* struct _objc_category {
     char *category_name;
     char *class_name;
     struct _objc_method_list *instance_methods;
     struct _objc_method_list *class_methods;
     struct _objc_protocol_list *protocols;
   };   */

static void
build_category_template (void)
{
  tree ptype, decls, *chain = NULL;

  objc_category_template = objc_start_struct (get_identifier (UTAG_CATEGORY));

  /* char *category_name; */
  decls = add_field_decl (string_type_node, "category_name", &chain);

  /* char *class_name; */
  add_field_decl (string_type_node, "class_name", &chain);

  /* struct _objc_method_list *instance_methods; */
  add_field_decl (objc_method_list_ptr, "instance_methods", &chain);

  /* struct _objc_method_list *class_methods; */
  add_field_decl (objc_method_list_ptr, "class_methods", &chain);

  /* struct _objc_protocol **protocol_list; */
  ptype = build_pointer_type (build_pointer_type (objc_protocol_template));
  add_field_decl (ptype, "protocol_list", &chain);

  objc_finish_struct (objc_category_template, decls);
}

/* struct _objc_selector {
     SEL sel_id;
     char *sel_type;
   }; */

static void
build_selector_template (void)
{
  tree decls, *chain = NULL;

  objc_selector_template = objc_start_struct (get_identifier (UTAG_SELECTOR));

  /* SEL sel_id; */
  decls = add_field_decl (objc_selector_type, "sel_id", &chain);

  /* char *sel_type; */
  add_field_decl (string_type_node, "sel_type", &chain);

  objc_finish_struct (objc_selector_template, decls);
}

/* struct _objc_class {
     struct _objc_class *isa;
     struct _objc_class *super_class;
     char *name;
     long version;
     long info;
     long instance_size;
     struct _objc_ivar_list *ivars;
     struct _objc_method_list *methods;
     #ifdef __NEXT_RUNTIME__
       struct objc_cache *cache;
     #else
       struct sarray *dtable;
       struct _objc_class *subclass_list;
       struct _objc_class *sibling_class;
     #endif
     struct _objc_protocol_list *protocols;
     #ifdef __NEXT_RUNTIME__
       void *sel_id;
     #endif
     void *gc_object_type;
   };  */

/* NB: The 'sel_id' and 'gc_object_type' fields are not being used by
   the NeXT/Apple runtime; still, the compiler must generate them to
   maintain backward binary compatibility (and to allow for future
   expansion).  */

static void
build_class_template (void)
{
  tree ptype, decls, *chain = NULL;

  objc_class_template = objc_start_struct (get_identifier (UTAG_CLASS));

  /* struct _objc_class *isa; */
  decls = add_field_decl (build_pointer_type (objc_class_template),
                          "isa", &chain);

  /* struct _objc_class *super_class; */
  add_field_decl (build_pointer_type (objc_class_template),
                  "super_class", &chain);

  /* char *name; */
  add_field_decl (string_type_node, "name", &chain);

  /* long version; */
  add_field_decl (long_integer_type_node, "version", &chain);

  /* long info; */
  add_field_decl (long_integer_type_node, "info", &chain);

  /* long instance_size; */
  add_field_decl (long_integer_type_node, "instance_size", &chain);

  /* struct _objc_ivar_list *ivars; */
  add_field_decl (objc_ivar_list_ptr,"ivars", &chain);

  /* struct _objc_method_list *methods; */
  add_field_decl (objc_method_list_ptr, "methods", &chain);

  if (flag_next_runtime)
    {
      /* struct objc_cache *cache; */
      ptype = build_pointer_type (xref_tag (RECORD_TYPE,
                                            get_identifier ("objc_cache")));
      add_field_decl (ptype, "cache", &chain);
    }
  else
    {
      /* struct sarray *dtable; */
      ptype = build_pointer_type(xref_tag (RECORD_TYPE,
                                           get_identifier ("sarray")));
      add_field_decl (ptype, "dtable", &chain);

      /* struct objc_class *subclass_list; */
      ptype = build_pointer_type (objc_class_template);
      add_field_decl (ptype, "subclass_list", &chain);

      /* struct objc_class *sibling_class; */
      ptype = build_pointer_type (objc_class_template);
      add_field_decl (ptype, "sibling_class", &chain);
    }

  /* struct _objc_protocol **protocol_list; */
  ptype = build_pointer_type (build_pointer_type
                              (xref_tag (RECORD_TYPE,
                                         get_identifier (UTAG_PROTOCOL))));
  add_field_decl (ptype, "protocol_list", &chain);

  if (flag_next_runtime)
    {
      /* void *sel_id; */
      add_field_decl (build_pointer_type (void_type_node), "sel_id", &chain);
    }

  /* void *gc_object_type; */
  add_field_decl (build_pointer_type (void_type_node),
                  "gc_object_type", &chain);

  objc_finish_struct (objc_class_template, decls);
}

/* Generate appropriate forward declarations for an implementation.  */

static void
synth_forward_declarations (void)
{
  tree an_id;

  /* static struct objc_class _OBJC_CLASS_<my_name>; */
  UOBJC_CLASS_decl = build_metadata_decl ("_OBJC_CLASS",
                                          objc_class_template);

  /* static struct objc_class _OBJC_METACLASS_<my_name>; */
  UOBJC_METACLASS_decl = build_metadata_decl ("_OBJC_METACLASS",
                                                  objc_class_template);

  /* Pre-build the following entities - for speed/convenience.  */

  an_id = get_identifier ("super_class");
  ucls_super_ref = objc_build_component_ref (UOBJC_CLASS_decl, an_id);
  uucls_super_ref = objc_build_component_ref (UOBJC_METACLASS_decl, an_id);
}

static void
error_with_ivar (const char *message, tree decl)
{
  error_at (DECL_SOURCE_LOCATION (decl), "%s %qs",
            message, identifier_to_locale (gen_declaration (decl)));

}

static void
check_ivars (tree inter, tree imp)
{
  tree intdecls = CLASS_RAW_IVARS (inter);
  tree impdecls = CLASS_RAW_IVARS (imp);

  while (1)
    {
      tree t1, t2;

#ifdef OBJCPLUS
      if (intdecls && TREE_CODE (intdecls) == TYPE_DECL)
        intdecls = TREE_CHAIN (intdecls);
#endif
      if (intdecls == 0 && impdecls == 0)
        break;
      if (intdecls == 0 || impdecls == 0)
        {
          error ("inconsistent instance variable specification");
          break;
        }

      t1 = TREE_TYPE (intdecls); t2 = TREE_TYPE (impdecls);

      if (!comptypes (t1, t2)
          || !tree_int_cst_equal (DECL_INITIAL (intdecls),
                                  DECL_INITIAL (impdecls)))
        {
          if (DECL_NAME (intdecls) == DECL_NAME (impdecls))
            {
              error_with_ivar ("conflicting instance variable type",
                               impdecls);
              error_with_ivar ("previous declaration of",
                               intdecls);
            }
          else                  /* both the type and the name don't match */
            {
              error ("inconsistent instance variable specification");
              break;
            }
        }

      else if (DECL_NAME (intdecls) != DECL_NAME (impdecls))
        {
          error_with_ivar ("conflicting instance variable name",
                           impdecls);
          error_with_ivar ("previous declaration of",
                           intdecls);
        }

      intdecls = DECL_CHAIN (intdecls);
      impdecls = DECL_CHAIN (impdecls);
    }
}

/* Set 'objc_super_template' to the data type node for 'struct _objc_super'.
   This needs to be done just once per compilation.  */

/* struct _objc_super {
     struct _objc_object *self;
     struct _objc_class *super_class;
   };  */

static void
build_super_template (void)
{
  tree decls, *chain = NULL;

  objc_super_template = objc_start_struct (get_identifier (UTAG_SUPER));

  /* struct _objc_object *self; */
  decls = add_field_decl (objc_object_type, "self", &chain);

  /* struct _objc_class *super_class; */
  add_field_decl (build_pointer_type (objc_class_template),
                  "super_class", &chain);

  objc_finish_struct (objc_super_template, decls);
}

/* struct _objc_ivar {
     char *ivar_name;
     char *ivar_type;
     int ivar_offset;
   };  */

static tree
build_ivar_template (void)
{
  tree objc_ivar_id, objc_ivar_record;
  tree decls, *chain = NULL;

  objc_ivar_id = get_identifier (UTAG_IVAR);
  objc_ivar_record = objc_start_struct (objc_ivar_id);

  /* char *ivar_name; */
  decls = add_field_decl (string_type_node, "ivar_name", &chain);

  /* char *ivar_type; */
  add_field_decl (string_type_node, "ivar_type", &chain);

  /* int ivar_offset; */
  add_field_decl (integer_type_node, "ivar_offset", &chain);

  objc_finish_struct (objc_ivar_record, decls);

  return objc_ivar_record;
}

/* struct {
     int ivar_count;
     struct objc_ivar ivar_list[ivar_count];
   };  */

static tree
build_ivar_list_template (tree list_type, int size)
{
  tree objc_ivar_list_record;
  tree array_type, decls, *chain = NULL;

  objc_ivar_list_record = objc_start_struct (NULL_TREE);

  /* int ivar_count; */
  decls = add_field_decl (integer_type_node, "ivar_count", &chain);

  /* struct objc_ivar ivar_list[]; */
  array_type = build_sized_array_type (list_type, size);
  add_field_decl (array_type, "ivar_list", &chain);

  objc_finish_struct (objc_ivar_list_record, decls);

  return objc_ivar_list_record;
}

/* struct {
     struct _objc__method_prototype_list *method_next;
     int method_count;
     struct objc_method method_list[method_count];
   };  */

static tree
build_method_list_template (tree list_type, int size)
{
  tree objc_ivar_list_record;
  tree array_type, decls, *chain = NULL;

  objc_ivar_list_record = objc_start_struct (NULL_TREE);

  /* struct _objc__method_prototype_list *method_next; */
  decls = add_field_decl (objc_method_proto_list_ptr, "method_next", &chain);

  /* int method_count; */
  add_field_decl (integer_type_node, "method_count", &chain);

  /* struct objc_method method_list[]; */
  array_type = build_sized_array_type (list_type, size);
  add_field_decl (array_type, "method_list", &chain);

  objc_finish_struct (objc_ivar_list_record, decls);

  return objc_ivar_list_record;
}

static tree
build_ivar_list_initializer (tree type, tree field_decl)
{
  VEC(constructor_elt,gc) *inits = NULL;

  do
    {
      VEC(constructor_elt,gc) *ivar = NULL;
      tree id;

      /* Set name.  */
      if (DECL_NAME (field_decl))
        CONSTRUCTOR_APPEND_ELT (ivar, NULL_TREE,
                                add_objc_string (DECL_NAME (field_decl),
                                                 meth_var_names));
      else
        /* Unnamed bit-field ivar (yuck).  */
        CONSTRUCTOR_APPEND_ELT (ivar, NULL_TREE, build_int_cst (NULL_TREE, 0));

      /* Set type.  */
      encode_field_decl (field_decl,
                         obstack_object_size (&util_obstack),
                         OBJC_ENCODE_DONT_INLINE_DEFS);

      /* Null terminate string.  */
      obstack_1grow (&util_obstack, 0);
      id = add_objc_string (get_identifier (XOBFINISH (&util_obstack, char *)),
                            meth_var_types);
      CONSTRUCTOR_APPEND_ELT (ivar, NULL_TREE, id);
      obstack_free (&util_obstack, util_firstobj);

      /* Set offset.  */
      CONSTRUCTOR_APPEND_ELT (ivar, NULL_TREE, byte_position (field_decl));
      CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE,
                              objc_build_constructor (type, ivar));
      do
        field_decl = DECL_CHAIN (field_decl);
      while (field_decl && TREE_CODE (field_decl) != FIELD_DECL);
    }
  while (field_decl);

  return objc_build_constructor (build_array_type (type, 0), inits);
}

static tree
generate_ivars_list (tree type, const char *name, int size, tree list)
{
  tree decl;
  VEC(constructor_elt,gc) *inits = NULL;

  decl = start_var_decl (type, synth_id_with_class_suffix
                               (name, objc_implementation_context));

  CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, build_int_cst (NULL_TREE, size));
  CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE, list);

  finish_var_decl (decl,
                   objc_build_constructor (TREE_TYPE (decl), inits));

  return decl;
}

/* Count only the fields occurring in T.  */

static int
ivar_list_length (tree t)
{
  int count = 0;

  for (; t; t = DECL_CHAIN (t))
    if (TREE_CODE (t) == FIELD_DECL)
      ++count;

  return count;
}

static void
generate_ivar_lists (void)
{
  tree initlist, ivar_list_template, chain;
  int size;

  generating_instance_variables = 1;

  if (!objc_ivar_template)
    objc_ivar_template = build_ivar_template ();

  /* Only generate class variables for the root of the inheritance
     hierarchy since these will be the same for every class.  */

  if (CLASS_SUPER_NAME (implementation_template) == NULL_TREE
      && (chain = TYPE_FIELDS (objc_class_template)))
    {
      size = ivar_list_length (chain);

      ivar_list_template = build_ivar_list_template (objc_ivar_template, size);
      initlist = build_ivar_list_initializer (objc_ivar_template, chain);

      UOBJC_CLASS_VARIABLES_decl
        = generate_ivars_list (ivar_list_template, "_OBJC_CLASS_VARIABLES",
                               size, initlist);
    }
  else
    UOBJC_CLASS_VARIABLES_decl = 0;

  chain = CLASS_IVARS (implementation_template);
  if (chain)
    {
      size = ivar_list_length (chain);
      ivar_list_template = build_ivar_list_template (objc_ivar_template, size);
      initlist = build_ivar_list_initializer (objc_ivar_template, chain);

      UOBJC_INSTANCE_VARIABLES_decl
        = generate_ivars_list (ivar_list_template, "_OBJC_INSTANCE_VARIABLES",
                               size, initlist);
    }
  else
    UOBJC_INSTANCE_VARIABLES_decl = 0;

  generating_instance_variables = 0;
}

static tree
build_dispatch_table_initializer (tree type, tree entries)
{
  VEC(constructor_elt,gc) *inits = NULL;

  do
    {
      VEC(constructor_elt,gc) *elems = NULL;
      tree expr;

      CONSTRUCTOR_APPEND_ELT (elems, NULL_TREE,
                              build_selector (METHOD_SEL_NAME (entries)));

      /* Generate the method encoding if we don't have one already.  */
      if (! METHOD_ENCODING (entries))
        METHOD_ENCODING (entries) =
          encode_method_prototype (entries);

      CONSTRUCTOR_APPEND_ELT (elems, NULL_TREE,
                              add_objc_string (METHOD_ENCODING (entries),
                                               meth_var_types));

      expr = convert (ptr_type_node,
                      build_unary_op (input_location, ADDR_EXPR,
                                      METHOD_DEFINITION (entries), 1));
      CONSTRUCTOR_APPEND_ELT (elems, NULL_TREE, expr);

      CONSTRUCTOR_APPEND_ELT (inits, NULL_TREE,
                              objc_build_constructor (type, elems));

      entries = DECL_CHAIN (entries);
    }
  while (entries);

  return objc_build_constructor (build_array_type (type, 0), inits);
}

/* To accomplish method prototyping without generating all kinds of
   inane warnings, the definition of the dispatch table entries were
   changed from:

        struct objc_method { SEL _cmd; ...; id (*_imp)(); };
   to:
        struct objc_method { SEL _cmd; ...; void *_imp; };  */

static tree
build_method_template (void)
{
  tree _SLT_record;
  tree decls, *chain = NULL;

  _SLT_record = objc_start_struct (get_identifier (UTAG_METHOD));

  /* SEL _cmd; */
  decls = add_field_decl (objc_selector_type, "_cmd", &chain);

  /* char *method_types; */
  add_field_decl (string_type_node, "method_types", &chain);

  /* void *_imp; */
  add_field_decl (build_pointer_type (void_type_node), "_imp", &chain);

  objc_finish_struct (_SLT_record, decls);

  return _SLT_record;
}


static tree
generate_dispatch_table (tree type, const char *name, int size, tree list)
{
  tree decl;
  VEC(constructor_elt,gc) *v = NULL;

  decl = start_var_decl (type, synth_id_with_class_suffix
                               (name, objc_implementation_context));

  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, integer_zero_node);
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (integer_type_node, size));
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, list);

  finish_var_decl (decl,
                   objc_build_constructor (TREE_TYPE (decl), v));

  return decl;
}

static void
mark_referenced_methods (void)
{
  struct imp_entry *impent;
  tree chain;

  for (impent = imp_list; impent; impent = impent->next)
    {
      chain = CLASS_CLS_METHODS (impent->imp_context);
      while (chain)
        {
          cgraph_mark_needed_node (cgraph_node (METHOD_DEFINITION (chain)));
          chain = DECL_CHAIN (chain);
        }

      chain = CLASS_NST_METHODS (impent->imp_context);
      while (chain)
        {
          cgraph_mark_needed_node (cgraph_node (METHOD_DEFINITION (chain)));
          chain = DECL_CHAIN (chain);
        }
    }
}

static void
generate_dispatch_tables (void)
{
  tree initlist, chain, method_list_template;
  int size;

  if (!objc_method_template)
    objc_method_template = build_method_template ();

  chain = CLASS_CLS_METHODS (objc_implementation_context);
  if (chain)
    {
      size = list_length (chain);

      method_list_template
        = build_method_list_template (objc_method_template, size);
      initlist
        = build_dispatch_table_initializer (objc_method_template, chain);

      UOBJC_CLASS_METHODS_decl
        = generate_dispatch_table (method_list_template,
                                   ((TREE_CODE (objc_implementation_context)
                                     == CLASS_IMPLEMENTATION_TYPE)
                                    ? "_OBJC_CLASS_METHODS"
                                    : "_OBJC_CATEGORY_CLASS_METHODS"),
                                   size, initlist);
    }
  else
    UOBJC_CLASS_METHODS_decl = 0;

  chain = CLASS_NST_METHODS (objc_implementation_context);
  if (chain)
    {
      size = list_length (chain);

      method_list_template
        = build_method_list_template (objc_method_template, size);
      initlist
        = build_dispatch_table_initializer (objc_method_template, chain);

      if (TREE_CODE (objc_implementation_context) == CLASS_IMPLEMENTATION_TYPE)
        UOBJC_INSTANCE_METHODS_decl
          = generate_dispatch_table (method_list_template,
                                     "_OBJC_INSTANCE_METHODS",
                                     size, initlist);
      else
        /* We have a category.  */
        UOBJC_INSTANCE_METHODS_decl
          = generate_dispatch_table (method_list_template,
                                     "_OBJC_CATEGORY_INSTANCE_METHODS",
                                     size, initlist);
    }
  else
    UOBJC_INSTANCE_METHODS_decl = 0;
}

static tree
generate_protocol_list (tree i_or_p)
{
  tree array_type, ptype, refs_decl, lproto, e, plist;
  int size = 0;
  const char *ref_name;
  VEC(constructor_elt,gc) *v = NULL;

  switch (TREE_CODE (i_or_p))
    {
    case CLASS_INTERFACE_TYPE:
    case CATEGORY_INTERFACE_TYPE:
      plist = CLASS_PROTOCOL_LIST (i_or_p);
      break;
    case PROTOCOL_INTERFACE_TYPE:
      plist = PROTOCOL_LIST (i_or_p);
      break;
    default:
      gcc_unreachable ();
    }

  /* Compute size.  */
  for (lproto = plist; lproto; lproto = TREE_CHAIN (lproto))
    if (TREE_CODE (TREE_VALUE (lproto)) == PROTOCOL_INTERFACE_TYPE
        && PROTOCOL_FORWARD_DECL (TREE_VALUE (lproto)))
      size++;

  /* Build initializer.  */
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
  e = build_int_cst (build_pointer_type (objc_protocol_template), size);
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, e);

  for (lproto = plist; lproto; lproto = TREE_CHAIN (lproto))
    {
      tree pval = TREE_VALUE (lproto);

      if (TREE_CODE (pval) == PROTOCOL_INTERFACE_TYPE
          && PROTOCOL_FORWARD_DECL (pval))
        {
          e = build_unary_op (input_location, ADDR_EXPR, 
                              PROTOCOL_FORWARD_DECL (pval), 0);
          CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, e);
        }
    }

  /* static struct objc_protocol *refs[n]; */

  switch (TREE_CODE (i_or_p))
    {
    case PROTOCOL_INTERFACE_TYPE:
      ref_name = synth_id_with_class_suffix ("_OBJC_PROTOCOL_REFS", i_or_p);
      break;
    case CLASS_INTERFACE_TYPE:
      ref_name = synth_id_with_class_suffix ("_OBJC_CLASS_PROTOCOLS", i_or_p);
      break;
    case CATEGORY_INTERFACE_TYPE:
      ref_name = synth_id_with_class_suffix ("_OBJC_CATEGORY_PROTOCOLS", i_or_p);
      break;
    default:
      gcc_unreachable ();
    }

  ptype = build_pointer_type (objc_protocol_template);
  array_type = build_sized_array_type (ptype, size + 3);
  refs_decl = start_var_decl (array_type, ref_name);

  finish_var_decl (refs_decl,
                   objc_build_constructor (TREE_TYPE (refs_decl), v));

  return refs_decl;
}

static tree
build_category_initializer (tree type, tree cat_name, tree class_name,
                            tree instance_methods, tree class_methods,
                            tree protocol_list)
{
  tree expr;
  VEC(constructor_elt,gc) *v = NULL;

  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, cat_name);
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, class_name);

  if (!instance_methods)
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      expr = convert (objc_method_list_ptr,
                      build_unary_op (input_location, ADDR_EXPR, 
                                      instance_methods, 0));
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
    }
  if (!class_methods)
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      expr = convert (objc_method_list_ptr,
                      build_unary_op (input_location, ADDR_EXPR, 
                                      class_methods, 0));
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
    }

  /* protocol_list = */
  if (!protocol_list)
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      expr = convert (build_pointer_type
                      (build_pointer_type
                       (objc_protocol_template)),
                      build_unary_op (input_location, ADDR_EXPR, 
                                      protocol_list, 0));
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
    }

  return objc_build_constructor (type, v);
}

/* struct _objc_class {
     struct objc_class *isa;
     struct objc_class *super_class;
     char *name;
     long version;
     long info;
     long instance_size;
     struct objc_ivar_list *ivars;
     struct objc_method_list *methods;
     if (flag_next_runtime)
       struct objc_cache *cache;
     else {
       struct sarray *dtable;
       struct objc_class *subclass_list;
       struct objc_class *sibling_class;
     }
     struct objc_protocol_list *protocols;
     if (flag_next_runtime)
       void *sel_id;
     void *gc_object_type;
   };  */

static tree
build_shared_structure_initializer (tree type, tree isa, tree super,
                                    tree name, tree size, int status,
                                    tree dispatch_table, tree ivar_list,
                                    tree protocol_list)
{
  tree expr;
  VEC(constructor_elt,gc) *v = NULL;

  /* isa = */
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, isa);

  /* super_class = */
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, super);

  /* name = */
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, default_conversion (name));

  /* version = */
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
                          build_int_cst (long_integer_type_node, 0));

  /* info = */
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
                          build_int_cst (long_integer_type_node, status));

  /* instance_size = */
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
                          convert (long_integer_type_node, size));

  /* objc_ivar_list = */
  if (!ivar_list)
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      expr = convert (objc_ivar_list_ptr,
                      build_unary_op (input_location, ADDR_EXPR, 
                                      ivar_list, 0));
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
    }

  /* objc_method_list = */
  if (!dispatch_table)
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      expr = convert (objc_method_list_ptr,
                      build_unary_op (input_location, ADDR_EXPR, 
                                      dispatch_table, 0));
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
    }

  if (flag_next_runtime)
    /* method_cache = */
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      /* dtable = */
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));

      /* subclass_list = */
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));

      /* sibling_class = */
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
    }

  /* protocol_list = */
  if (! protocol_list)
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));
  else
    {
      expr = convert (build_pointer_type
                      (build_pointer_type
                       (objc_protocol_template)),
                      build_unary_op (input_location, ADDR_EXPR, 
                                      protocol_list, 0));
      CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, expr);
    }

  if (flag_next_runtime)
    /* sel_id = NULL */
    CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));

  /* gc_object_type = NULL */
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (NULL_TREE, 0));

  return objc_build_constructor (type, v);
}

/* Retrieve category interface CAT_NAME (if any) associated with CLASS.  */

static inline tree
lookup_category (tree klass, tree cat_name)
{
  tree category = CLASS_CATEGORY_LIST (klass);

  while (category && CLASS_SUPER_NAME (category) != cat_name)
    category = CLASS_CATEGORY_LIST (category);
  return category;
}

/* static struct objc_category _OBJC_CATEGORY_<name> = { ... };  */

static void
generate_category (struct imp_entry *impent)
{
  tree initlist, cat_name_expr, class_name_expr;
  tree protocol_decl, category;
  tree cat = impent->imp_context;

  implementation_template = impent->imp_template;
  UOBJC_CLASS_decl = impent->class_decl;
  UOBJC_METACLASS_decl = impent->meta_decl;

  add_class_reference (CLASS_NAME (cat));
  cat_name_expr = add_objc_string (CLASS_SUPER_NAME (cat), class_names);

  class_name_expr = add_objc_string (CLASS_NAME (cat), class_names);

  category = lookup_category (implementation_template,
                                CLASS_SUPER_NAME (cat));

  if (category && CLASS_PROTOCOL_LIST (category))
    {
      generate_protocol_references (CLASS_PROTOCOL_LIST (category));
      protocol_decl = generate_protocol_list (category);
    }
  else
    protocol_decl = 0;

  initlist = build_category_initializer (TREE_TYPE (UOBJC_CLASS_decl),
                                         cat_name_expr, class_name_expr,
                                         UOBJC_INSTANCE_METHODS_decl,
                                         UOBJC_CLASS_METHODS_decl,
                                         protocol_decl);
  /* Finish and initialize the forward decl.  */
  finish_var_decl (UOBJC_CLASS_decl, initlist);
}

/* static struct objc_class _OBJC_METACLASS_Foo={ ... };
   static struct objc_class _OBJC_CLASS_Foo={ ... };  */

static void
generate_shared_structures (struct imp_entry *impent)
{
  tree name_expr, super_expr, root_expr;
  tree my_root_id, my_super_id;
  tree cast_type, initlist, protocol_decl;
  int cls_flags;
  
  objc_implementation_context = impent->imp_context;
  implementation_template = impent->imp_template;
  UOBJC_CLASS_decl = impent->class_decl;
  UOBJC_METACLASS_decl = impent->meta_decl;
  cls_flags = impent->has_cxx_cdtors ? CLS_HAS_CXX_STRUCTORS : 0 ;
  
  my_super_id = CLASS_SUPER_NAME (implementation_template);
  if (my_super_id)
    {
      add_class_reference (my_super_id);

      /* Compute "my_root_id" - this is required for code generation.
         the "isa" for all meta class structures points to the root of
         the inheritance hierarchy (e.g. "__Object")...  */
      my_root_id = my_super_id;
      do
        {
          tree my_root_int = lookup_interface (my_root_id);

          if (my_root_int && CLASS_SUPER_NAME (my_root_int))
            my_root_id = CLASS_SUPER_NAME (my_root_int);
          else
            break;
        }
      while (1);
    }
  else
    /* No super class.  */
    my_root_id = CLASS_NAME (implementation_template);

  cast_type = build_pointer_type (objc_class_template);
  name_expr = add_objc_string (CLASS_NAME (implementation_template),
                               class_names);

  /* Install class `isa' and `super' pointers at runtime.  */
  if (my_super_id)
    super_expr = add_objc_string (my_super_id, class_names);
  else
    super_expr = integer_zero_node;
    
  super_expr = build_c_cast (input_location,
                                 cast_type, super_expr); /* cast! */

  root_expr = add_objc_string (my_root_id, class_names);
  root_expr = build_c_cast (input_location, cast_type, root_expr); /* cast! */

  if (CLASS_PROTOCOL_LIST (implementation_template))
    {
      generate_protocol_references
        (CLASS_PROTOCOL_LIST (implementation_template));
      protocol_decl = generate_protocol_list (implementation_template);
    }
  else
    protocol_decl = 0;

  /* static struct objc_class _OBJC_METACLASS_Foo = { ... }; */

  initlist
    = build_shared_structure_initializer
      (TREE_TYPE (UOBJC_METACLASS_decl),
       root_expr, super_expr, name_expr,
       convert (integer_type_node, TYPE_SIZE_UNIT (objc_class_template)),
       2 /*CLS_META*/,
       UOBJC_CLASS_METHODS_decl,
       UOBJC_CLASS_VARIABLES_decl,
       protocol_decl);

  finish_var_decl (UOBJC_METACLASS_decl, initlist);

  /* static struct objc_class _OBJC_CLASS_Foo={ ... }; */

  initlist
    = build_shared_structure_initializer
      (TREE_TYPE (UOBJC_CLASS_decl),
       build_unary_op (input_location, ADDR_EXPR, UOBJC_METACLASS_decl, 0),
       super_expr, name_expr,
       convert (integer_type_node,
                TYPE_SIZE_UNIT (CLASS_STATIC_TEMPLATE
                                (implementation_template))),
       1 /*CLS_FACTORY*/ | cls_flags,
       UOBJC_INSTANCE_METHODS_decl,
       UOBJC_INSTANCE_VARIABLES_decl,
       protocol_decl);

  finish_var_decl (UOBJC_CLASS_decl, initlist);
}


static const char *
synth_id_with_class_suffix (const char *preamble, tree ctxt)
{
  static char string[BUFSIZE];

  switch (TREE_CODE (ctxt))
    {
    case CLASS_IMPLEMENTATION_TYPE:
    case CLASS_INTERFACE_TYPE:
      sprintf (string, "%s_%s", preamble,
               IDENTIFIER_POINTER (CLASS_NAME (ctxt)));
      break;
    case CATEGORY_IMPLEMENTATION_TYPE:
    case CATEGORY_INTERFACE_TYPE:
      {
        /* We have a category.  */
        const char *const class_name
          = IDENTIFIER_POINTER (CLASS_NAME (objc_implementation_context));
        const char *const class_super_name
          = IDENTIFIER_POINTER (CLASS_SUPER_NAME (objc_implementation_context));
        sprintf (string, "%s_%s_%s", preamble, class_name, class_super_name);
        break;
    }
    case PROTOCOL_INTERFACE_TYPE:
      {
        const char *protocol_name = IDENTIFIER_POINTER (PROTOCOL_NAME (ctxt));
        sprintf (string, "%s_%s", preamble, protocol_name);
        break;
      }
    default:
      gcc_unreachable ();
    }

  return string;
}

/* If type is empty or only type qualifiers are present, add default
   type of id (otherwise grokdeclarator will default to int).  */
static inline tree
adjust_type_for_id_default (tree type)
{
  if (!type)
    type = make_node (TREE_LIST);

  if (!TREE_VALUE (type))
    TREE_VALUE (type) = objc_object_type;
  else if (TREE_CODE (TREE_VALUE (type)) == RECORD_TYPE
           && TYPED_OBJECT (TREE_VALUE (type)))
    error ("can not use an object as parameter to a method");

  return type;
}

/* Return a KEYWORD_DECL built using the specified key_name, arg_type,
   arg_name and attributes. (TODO: Rename KEYWORD_DECL to
   OBJC_METHOD_PARM_DECL ?)

   A KEYWORD_DECL is a tree representing the declaration of a
   parameter of an Objective-C method.  It is produced when parsing a
   fragment of Objective-C method declaration of the form

   keyworddecl:
     selector ':' '(' typename ')' identifier

   For example, take the Objective-C method

   -(NSString *)pathForResource:(NSString *)resource ofType:(NSString *)type; 

   the two fragments "pathForResource:(NSString *)resource" and
   "ofType:(NSString *)type" will generate a KEYWORD_DECL each.  The
   KEYWORD_DECL stores the 'key_name' (eg, identifier for
   "pathForResource"), the 'arg_type' (eg, tree representing a
   NSString *), the 'arg_name' (eg identifier for "resource") and
   potentially some attributes (for example, a tree representing
   __attribute__ ((unused)) if such an attribute was attached to a
   certain parameter).  You can access this information using the
   TREE_TYPE (for arg_type), KEYWORD_ARG_NAME (for arg_name),
   KEYWORD_KEY_NAME (for key_name), DECL_ATTRIBUTES (for attributes).

   'key_name' is an identifier node (and is optional as you can omit
   it in Objective-C methods).
   'arg_type' is a tree list (and is optional too if no parameter type
   was specified).
   'arg_name' is an identifier node and is required.
   'attributes' is an optional tree containing parameter attributes.  */
tree
objc_build_keyword_decl (tree key_name, tree arg_type, 
                         tree arg_name, tree attributes)
{
  tree keyword_decl;

  if (flag_objc1_only && attributes)
    error_at (input_location, "method argument attributes are not available in Objective-C 1.0");

  /* If no type is specified, default to "id".  */
  arg_type = adjust_type_for_id_default (arg_type);

  keyword_decl = make_node (KEYWORD_DECL);

  TREE_TYPE (keyword_decl) = arg_type;
  KEYWORD_ARG_NAME (keyword_decl) = arg_name;
  KEYWORD_KEY_NAME (keyword_decl) = key_name;
  DECL_ATTRIBUTES (keyword_decl) = attributes;

  return keyword_decl;
}

/* Given a chain of keyword_decl's, synthesize the full keyword selector.  */
static tree
build_keyword_selector (tree selector)
{
  int len = 0;
  tree key_chain, key_name;
  char *buf;

  /* Scan the selector to see how much space we'll need.  */
  for (key_chain = selector; key_chain; key_chain = TREE_CHAIN (key_chain))
    {
      switch (TREE_CODE (selector))
        {
        case KEYWORD_DECL:
          key_name = KEYWORD_KEY_NAME (key_chain);
          break;
        case TREE_LIST:
          key_name = TREE_PURPOSE (key_chain);
          break;
        default:
          gcc_unreachable ();
        }

      if (key_name)
        len += IDENTIFIER_LENGTH (key_name) + 1;
      else
        /* Just a ':' arg.  */
        len++;
    }

  buf = (char *) alloca (len + 1);
  /* Start the buffer out as an empty string.  */
  buf[0] = '\0';

  for (key_chain = selector; key_chain; key_chain = TREE_CHAIN (key_chain))
    {
      switch (TREE_CODE (selector))
        {
        case KEYWORD_DECL:
          key_name = KEYWORD_KEY_NAME (key_chain);
          break;
        case TREE_LIST:
          key_name = TREE_PURPOSE (key_chain);
          /* The keyword decl chain will later be used as a function
             argument chain.  Unhook the selector itself so as to not
             confuse other parts of the compiler.  */
          TREE_PURPOSE (key_chain) = NULL_TREE;
          break;
        default:
          gcc_unreachable ();
        }

      if (key_name)
        strcat (buf, IDENTIFIER_POINTER (key_name));
      strcat (buf, ":");
    }

  return get_identifier (buf);
}

/* Used for declarations and definitions.  */

static tree
build_method_decl (enum tree_code code, tree ret_type, tree selector,
                   tree add_args, bool ellipsis)
{
  tree method_decl;

  /* If no type is specified, default to "id".  */
  ret_type = adjust_type_for_id_default (ret_type);

  /* Note how a method_decl has a TREE_TYPE which is not the function
     type of the function implementing the method, but only the return
     type of the method.  We may want to change this, and store the
     entire function type in there (eg, it may be used to simplify
     dealing with attributes below).  */
  method_decl = make_node (code);
  TREE_TYPE (method_decl) = ret_type;

  /* If we have a keyword selector, create an identifier_node that
     represents the full selector name (`:' included)...  */
  if (TREE_CODE (selector) == KEYWORD_DECL)
    {
      METHOD_SEL_NAME (method_decl) = build_keyword_selector (selector);
      METHOD_SEL_ARGS (method_decl) = selector;
      METHOD_ADD_ARGS (method_decl) = add_args;
      METHOD_ADD_ARGS_ELLIPSIS_P (method_decl) = ellipsis;
    }
  else
    {
      METHOD_SEL_NAME (method_decl) = selector;
      METHOD_SEL_ARGS (method_decl) = NULL_TREE;
      METHOD_ADD_ARGS (method_decl) = NULL_TREE;
    }

  return method_decl;
}

#define METHOD_DEF 0
#define METHOD_REF 1

/* This routine processes objective-c method attributes. */

static void
objc_decl_method_attributes (tree *node, tree attributes, int flags)
{
  /* TODO: Replace the hackery below.  An idea would be to store the
     full function type in the method declaration (for example in
     TREE_TYPE) and then expose ObjC method declarations to c-family
     and they could deal with them by simply treating them as
     functions.  */

  /* Because of the dangers in the hackery below, we filter out any
     attribute that we do not know about.  For the ones we know about,
     we know that they work with the hackery.  For the other ones,
     there is no guarantee, so we have to filter them out.  */
  tree filtered_attributes = NULL_TREE;

  if (attributes)
    {
      tree attribute;
      for (attribute = attributes; attribute; attribute = TREE_CHAIN (attribute))
        {
          tree name = TREE_PURPOSE (attribute);
          
          if (is_attribute_p  ("deprecated", name)
              || is_attribute_p ("sentinel", name)
              || is_attribute_p ("noreturn", name))
            {
              /* An attribute that we support; add it to the filtered
                 attributes.  */
              filtered_attributes = chainon (filtered_attributes, 
                                             copy_node (attribute));
            }
          else if (is_attribute_p ("format", name))
            {
              /* "format" is special because before adding it to the
                 filtered attributes we need to adjust the specified
                 format by adding the hidden function parameters for
                 an Objective-C method (self, _cmd).  */
              tree new_attribute = copy_node (attribute);

              /* Check the arguments specified with the attribute, and
                 modify them adding 2 for the two hidden arguments.
                 Note how this differs from C++; according to the
                 specs, C++ does not do it so you have to add the +1
                 yourself.  For Objective-C, instead, the compiler
                 adds the +2 for you.  */

              /* The attribute arguments have not been checked yet, so
                 we need to be careful as they could be missing or
                 invalid.  If anything looks wrong, we skip the
                 process and the compiler will complain about it later
                 when it validates the attribute.  */
              /* Check that we have at least three arguments.  */
              if (TREE_VALUE (new_attribute)
                  && TREE_CHAIN (TREE_VALUE (new_attribute))
                  && TREE_CHAIN (TREE_CHAIN (TREE_VALUE (new_attribute))))
                {
                  tree second_argument = TREE_CHAIN (TREE_VALUE (new_attribute));
                  tree third_argument = TREE_CHAIN (second_argument);
                  tree number;

                  /* This is the second argument, the "string-index",
                     which specifies the index of the format string
                     argument.  Add 2.  */
                  number = TREE_VALUE (second_argument);
                  if (number
                      && TREE_CODE (number) == INTEGER_CST
                      && TREE_INT_CST_HIGH (number) == 0)
                    {
                      TREE_VALUE (second_argument) 
                        = build_int_cst (integer_type_node,
                                         TREE_INT_CST_LOW (number) + 2);
                    }
                  
                  /* This is the third argument, the "first-to-check",
                     which specifies the index of the first argument to
                     check.  This could be 0, meaning it is not available,
                     in which case we don't need to add 2.  Add 2 if not
                     0.  */
                  number = TREE_VALUE (third_argument);
                  if (number
                      && TREE_CODE (number) == INTEGER_CST
                      && TREE_INT_CST_HIGH (number) == 0
                      && TREE_INT_CST_LOW (number) != 0)
                    {
                      TREE_VALUE (third_argument) 
                        = build_int_cst (integer_type_node,
                                         TREE_INT_CST_LOW (number) + 2);
                    }
                }
              filtered_attributes = chainon (filtered_attributes,
                                             new_attribute);
            }
          else
            warning (OPT_Wattributes, "%qE attribute directive ignored", name);
        }
    }

  if (filtered_attributes)
    {
      /* This hackery changes the TREE_TYPE of the ObjC method
         declaration to be a function type, so that decl_attributes
         will treat the ObjC method as if it was a function.  Some
         attributes (sentinel, format) will be applied to the function
         type, changing it in place; so after calling decl_attributes,
         we extract the function type attributes and store them in
         METHOD_TYPE_ATTRIBUTES.  Some other attributes (noreturn,
         deprecated) are applied directly to the method declaration
         (by setting TREE_DEPRECATED and TREE_THIS_VOLATILE) so there
         is nothing to do.  */
      tree saved_type = TREE_TYPE (*node);
      TREE_TYPE (*node) = build_function_type 
        (TREE_VALUE (saved_type), get_arg_type_list (*node, METHOD_REF, 0));
      decl_attributes (node, filtered_attributes, flags);
      METHOD_TYPE_ATTRIBUTES (*node) = TYPE_ATTRIBUTES (TREE_TYPE (*node));
      TREE_TYPE (*node) = saved_type;
    }
}

bool 
objc_method_decl (enum tree_code opcode)
{
  return opcode == INSTANCE_METHOD_DECL || opcode == CLASS_METHOD_DECL;
}

/* Used by `build_objc_method_call' and `comp_proto_with_proto'.  Return
   an argument list for method METH.  CONTEXT is either METHOD_DEF or
   METHOD_REF, saying whether we are trying to define a method or call
   one.  SUPERFLAG says this is for a send to super; this makes a
   difference for the NeXT calling sequence in which the lookup and
   the method call are done together.  If METH is null, user-defined
   arguments (i.e., beyond self and _cmd) shall be represented by `...'.  */

static tree
get_arg_type_list (tree meth, int context, int superflag)
{
  tree arglist, akey;

  /* Receiver type.  */
  if (flag_next_runtime && superflag)
    arglist = build_tree_list (NULL_TREE, objc_super_type);
  else if (context == METHOD_DEF && TREE_CODE (meth) == INSTANCE_METHOD_DECL)
    arglist = build_tree_list (NULL_TREE, objc_instance_type);
  else
    arglist = build_tree_list (NULL_TREE, objc_object_type);

  /* Selector type - will eventually change to `int'.  */
  chainon (arglist, build_tree_list (NULL_TREE, objc_selector_type));

  /* No actual method prototype given -- assume that remaining arguments
     are `...'.  */
  if (!meth)
    return arglist;

  /* Build a list of argument types.  */
  for (akey = METHOD_SEL_ARGS (meth); akey; akey = DECL_CHAIN (akey))
    {
      tree arg_type = TREE_VALUE (TREE_TYPE (akey));

      /* Decay argument types for the underlying C function as appropriate.  */
      arg_type = objc_decay_parm_type (arg_type);

      chainon (arglist, build_tree_list (NULL_TREE, arg_type));
    }

  if (METHOD_ADD_ARGS (meth))
    {
      for (akey = TREE_CHAIN (METHOD_ADD_ARGS (meth));
           akey; akey = TREE_CHAIN (akey))
        {
          tree arg_type = TREE_TYPE (TREE_VALUE (akey));

          arg_type = objc_decay_parm_type (arg_type);

          chainon (arglist, build_tree_list (NULL_TREE, arg_type));
        }

      if (!METHOD_ADD_ARGS_ELLIPSIS_P (meth))
        goto lack_of_ellipsis;
    }
  else
    {
     lack_of_ellipsis:
      chainon (arglist, OBJC_VOID_AT_END);
    }

  return arglist;
}

static tree
check_duplicates (hash hsh, int methods, int is_class)
{
  tree meth = NULL_TREE;

  if (hsh)
    {
      meth = hsh->key;

      if (hsh->list)
        {
          /* We have two or more methods with the same name but
             different types.  */
          attr loop;

          /* But just how different are those types?  If
             -Wno-strict-selector-match is specified, we shall not
             complain if the differences are solely among types with
             identical size and alignment.  */
          if (!warn_strict_selector_match)
            {
              for (loop = hsh->list; loop; loop = loop->next)
                if (!comp_proto_with_proto (meth, loop->value, 0))
                  goto issue_warning;

              return meth;
            }

        issue_warning:
          if (methods)
            {
              bool type = TREE_CODE (meth) == INSTANCE_METHOD_DECL;

              warning_at (input_location, 0,
                          "multiple methods named %<%c%E%> found",
                          (is_class ? '+' : '-'),
                          METHOD_SEL_NAME (meth));
              inform (DECL_SOURCE_LOCATION (meth), "using %<%c%s%>",
                      (type ? '-' : '+'),
                      identifier_to_locale (gen_method_decl (meth)));
            }
          else
            {
              bool type = TREE_CODE (meth) == INSTANCE_METHOD_DECL;

              warning_at (input_location, 0,
                          "multiple selectors named %<%c%E%> found",
                          (is_class ? '+' : '-'),
                          METHOD_SEL_NAME (meth));
              inform (DECL_SOURCE_LOCATION (meth), "found %<%c%s%>",
                      (type ? '-' : '+'),
                      identifier_to_locale (gen_method_decl (meth)));
            }

          for (loop = hsh->list; loop; loop = loop->next)
            {
              bool type = TREE_CODE (loop->value) == INSTANCE_METHOD_DECL;

              inform (DECL_SOURCE_LOCATION (loop->value), "also found %<%c%s%>",
                      (type ? '-' : '+'),
                      identifier_to_locale (gen_method_decl (loop->value)));
            }
        }
    }
  return meth;
}

/* If RECEIVER is a class reference, return the identifier node for
   the referenced class.  RECEIVER is created by objc_get_class_reference,
   so we check the exact form created depending on which runtimes are
   used.  */

static tree
receiver_is_class_object (tree receiver, int self, int super)
{
  tree chain, exp, arg;

  /* The receiver is 'self' or 'super' in the context of a class method.  */
  if (objc_method_context
      && TREE_CODE (objc_method_context) == CLASS_METHOD_DECL
      && (self || super))
    return (super
            ? CLASS_SUPER_NAME (implementation_template)
            : CLASS_NAME (implementation_template));

  if (flag_next_runtime)
    {
      /* The receiver is a variable created by
         build_class_reference_decl.  */
      if (TREE_CODE (receiver) == VAR_DECL && IS_CLASS (TREE_TYPE (receiver)))
        /* Look up the identifier.  */
        for (chain = cls_ref_chain; chain; chain = TREE_CHAIN (chain))
          if (TREE_PURPOSE (chain) == receiver)
            return TREE_VALUE (chain);
    }

  /* The receiver is a function call that returns an id.  Check if
     it is a call to objc_getClass, if so, pick up the class name.  */
  if (TREE_CODE (receiver) == CALL_EXPR
      && (exp = CALL_EXPR_FN (receiver))
      && TREE_CODE (exp) == ADDR_EXPR
      && (exp = TREE_OPERAND (exp, 0))
      && TREE_CODE (exp) == FUNCTION_DECL
      /* For some reason, we sometimes wind up with multiple FUNCTION_DECL
         prototypes for objc_get_class().  Thankfully, they seem to share the
         same function type.  */
      && TREE_TYPE (exp) == TREE_TYPE (objc_get_class_decl)
      && !strcmp (IDENTIFIER_POINTER (DECL_NAME (exp)), TAG_GETCLASS)
      /* We have a call to objc_get_class/objc_getClass!  */
      && (arg = CALL_EXPR_ARG (receiver, 0)))
    {
      STRIP_NOPS (arg);
      if (TREE_CODE (arg) == ADDR_EXPR
          && (arg = TREE_OPERAND (arg, 0))
          && TREE_CODE (arg) == STRING_CST)
        /* Finally, we have the class name.  */
        return get_identifier (TREE_STRING_POINTER (arg));
    }
  return 0;
}
\f
/* If we are currently building a message expr, this holds
   the identifier of the selector of the message.  This is
   used when printing warnings about argument mismatches.  */

static tree current_objc_message_selector = 0;

tree
objc_message_selector (void)
{
  return current_objc_message_selector;
}

/* Construct an expression for sending a message.
   MESS has the object to send to in TREE_PURPOSE
   and the argument list (including selector) in TREE_VALUE.

   (*(<abstract_decl>(*)())_msg)(receiver, selTransTbl[n], ...);
   (*(<abstract_decl>(*)())_msgSuper)(receiver, selTransTbl[n], ...);  */

tree
objc_build_message_expr (tree mess)
{
  tree receiver = TREE_PURPOSE (mess);
  tree sel_name;
#ifdef OBJCPLUS
  tree args = TREE_PURPOSE (TREE_VALUE (mess));
#else
  tree args = TREE_VALUE (mess);
#endif
  tree method_params = NULL_TREE;

  if (TREE_CODE (receiver) == ERROR_MARK || TREE_CODE (args) == ERROR_MARK)
    return error_mark_node;

  /* Obtain the full selector name.  */
  switch (TREE_CODE (args))
    {
    case IDENTIFIER_NODE:
      /* A unary selector.  */
      sel_name = args;
      break;
    case TREE_LIST:
      sel_name = build_keyword_selector (args);
      break;
    default:
      gcc_unreachable ();
    }

  /* Build the parameter list to give to the method.  */
  if (TREE_CODE (args) == TREE_LIST)
#ifdef OBJCPLUS
    method_params = chainon (args, TREE_VALUE (TREE_VALUE (mess)));
#else
    {
      tree chain = args, prev = NULL_TREE;

      /* We have a keyword selector--check for comma expressions.  */
      while (chain)
        {
          tree element = TREE_VALUE (chain);

          /* We have a comma expression, must collapse...  */
          if (TREE_CODE (element) == TREE_LIST)
            {
              if (prev)
                TREE_CHAIN (prev) = element;
              else
                args = element;
            }
          prev = chain;
          chain = TREE_CHAIN (chain);
        }
      method_params = args;
    }
#endif

#ifdef OBJCPLUS
  if (processing_template_decl)
    /* Must wait until template instantiation time.  */
    return build_min_nt (MESSAGE_SEND_EXPR, receiver, sel_name,
                         method_params);
#endif

  return objc_finish_message_expr (receiver, sel_name, method_params);
}

/* Look up method SEL_NAME that would be suitable for receiver
   of type 'id' (if IS_CLASS is zero) or 'Class' (if IS_CLASS is
   nonzero), and report on any duplicates.  */

static tree
lookup_method_in_hash_lists (tree sel_name, int is_class)
{
  hash method_prototype = NULL;

  if (!is_class)
    method_prototype = hash_lookup (nst_method_hash_list,
                                    sel_name);

  if (!method_prototype)
    {
      method_prototype = hash_lookup (cls_method_hash_list,
                                      sel_name);
      is_class = 1;
    }

  return check_duplicates (method_prototype, 1, is_class);
}

/* The 'objc_finish_message_expr' routine is called from within
   'objc_build_message_expr' for non-template functions.  In the case of
   C++ template functions, it is called from 'build_expr_from_tree'
   (in decl2.c) after RECEIVER and METHOD_PARAMS have been expanded.  */

tree
objc_finish_message_expr (tree receiver, tree sel_name, tree method_params)
{
  tree method_prototype = NULL_TREE, rprotos = NULL_TREE, rtype;
  tree selector, retval, class_tree;
  int self, super, have_cast;

  /* We have used the receiver, so mark it as read.  */
  mark_exp_read (receiver);

  /* Extract the receiver of the message, as well as its type
     (where the latter may take the form of a cast or be inferred
     from the implementation context).  */
  rtype = receiver;
  while (TREE_CODE (rtype) == COMPOUND_EXPR
              || TREE_CODE (rtype) == MODIFY_EXPR
              || CONVERT_EXPR_P (rtype)
              || TREE_CODE (rtype) == COMPONENT_REF)
    rtype = TREE_OPERAND (rtype, 0);

  self = (rtype == self_decl);
  super = (rtype == UOBJC_SUPER_decl);
  rtype = TREE_TYPE (receiver);

  have_cast = (TREE_CODE (receiver) == NOP_EXPR
               || (TREE_CODE (receiver) == COMPOUND_EXPR
                   && !IS_SUPER (rtype)));

  /* If we are calling [super dealloc], reset our warning flag.  */
  if (super && !strcmp ("dealloc", IDENTIFIER_POINTER (sel_name)))
    should_call_super_dealloc = 0;

  /* If the receiver is a class object, retrieve the corresponding
     @interface, if one exists. */
  class_tree = receiver_is_class_object (receiver, self, super);

  /* Now determine the receiver type (if an explicit cast has not been
     provided).  */
  if (!have_cast)
    {
      if (class_tree)
        rtype = lookup_interface (class_tree);
      /* Handle `self' and `super'.  */
      else if (super)
        {
          if (!CLASS_SUPER_NAME (implementation_template))
            {
              error ("no super class declared in @interface for %qE",
                     CLASS_NAME (implementation_template));
              return error_mark_node;
            }
          rtype = lookup_interface (CLASS_SUPER_NAME (implementation_template));
        }
      else if (self)
        rtype = lookup_interface (CLASS_NAME (implementation_template));
    }

  /* If receiver is of type `id' or `Class' (or if the @interface for a
     class is not visible), we shall be satisfied with the existence of
     any instance or class method. */
  if (objc_is_id (rtype))
    {
      class_tree = (IS_CLASS (rtype) ? objc_class_name : NULL_TREE);
      rprotos = (TYPE_HAS_OBJC_INFO (TREE_TYPE (rtype))
                 ? TYPE_OBJC_PROTOCOL_LIST (TREE_TYPE (rtype))
                 : NULL_TREE);
      rtype = NULL_TREE;

      if (rprotos)
        {
          /* If messaging 'id <Protos>' or 'Class <Proto>', first search
             in protocols themselves for the method prototype.  */
          method_prototype
            = lookup_method_in_protocol_list (rprotos, sel_name,
                                              class_tree != NULL_TREE);

          /* If messaging 'Class <Proto>' but did not find a class method
             prototype, search for an instance method instead, and warn
             about having done so.  */
          if (!method_prototype && !rtype && class_tree != NULL_TREE)
            {
              method_prototype
                = lookup_method_in_protocol_list (rprotos, sel_name, 0);

              if (method_prototype)
                warning (0, "found %<-%E%> instead of %<+%E%> in protocol(s)",
                         sel_name, sel_name);
            }
        }
    }
  else if (rtype)
    {
      tree orig_rtype = rtype;

      if (TREE_CODE (rtype) == POINTER_TYPE)
        rtype = TREE_TYPE (rtype);
      /* Traverse typedef aliases */
      while (TREE_CODE (rtype) == RECORD_TYPE && OBJC_TYPE_NAME (rtype)
             && TREE_CODE (OBJC_TYPE_NAME (rtype)) == TYPE_DECL
             && DECL_ORIGINAL_TYPE (OBJC_TYPE_NAME (rtype)))
        rtype = DECL_ORIGINAL_TYPE (OBJC_TYPE_NAME (rtype));
      if (TYPED_OBJECT (rtype))
        {
          rprotos = TYPE_OBJC_PROTOCOL_LIST (rtype);
          rtype = TYPE_OBJC_INTERFACE (rtype);
        }
      /* If we could not find an @interface declaration, we must have
         only seen a @class declaration; so, we cannot say anything
         more intelligent about which methods the receiver will
         understand. */
      if (!rtype || TREE_CODE (rtype) == IDENTIFIER_NODE)
        {
          rtype = NULL_TREE;
          /* We could not find an @interface declaration, yet Message maybe in a 
             @class's protocol. */
          if (!method_prototype && rprotos)
            method_prototype
              = lookup_method_in_protocol_list (rprotos, sel_name, 0);
        }
      else if (TREE_CODE (rtype) == CLASS_INTERFACE_TYPE
          || TREE_CODE (rtype) == CLASS_IMPLEMENTATION_TYPE)
        {
          /* We have a valid ObjC class name.  Look up the method name
             in the published @interface for the class (and its
             superclasses). */
          method_prototype
            = lookup_method_static (rtype, sel_name, class_tree != NULL_TREE);

          /* If the method was not found in the @interface, it may still
             exist locally as part of the @implementation.  */
          if (!method_prototype && objc_implementation_context
             && CLASS_NAME (objc_implementation_context)
                == OBJC_TYPE_NAME (rtype))
            method_prototype
              = lookup_method
                ((class_tree
                  ? CLASS_CLS_METHODS (objc_implementation_context)
                  : CLASS_NST_METHODS (objc_implementation_context)),
                  sel_name);

          /* If we haven't found a candidate method by now, try looking for
             it in the protocol list.  */
          if (!method_prototype && rprotos)
            method_prototype
              = lookup_method_in_protocol_list (rprotos, sel_name,
                                                class_tree != NULL_TREE);
        }
      else
        {
          warning (0, "invalid receiver type %qs",
                   identifier_to_locale (gen_type_name (orig_rtype)));
          /* After issuing the "invalid receiver" warning, perform method
             lookup as if we were messaging 'id'.  */
          rtype = rprotos = NULL_TREE;
        }
    }


  /* For 'id' or 'Class' receivers, search in the global hash table
     as a last resort.  For all receivers, warn if protocol searches
     have failed.  */
  if (!method_prototype)
    {
      if (rprotos)
        warning (0, "%<%c%E%> not found in protocol(s)",
                 (class_tree ? '+' : '-'),
                 sel_name);

      if (!rtype)
        method_prototype
          = lookup_method_in_hash_lists (sel_name, class_tree != NULL_TREE);
    }

  if (!method_prototype) 
    {
      static bool warn_missing_methods = false;

      if (rtype)
        warning (0, "%qE may not respond to %<%c%E%>",
                 OBJC_TYPE_NAME (rtype),
                 (class_tree ? '+' : '-'),
                 sel_name);
      /* If we are messaging an 'id' or 'Class' object and made it here,
         then we have failed to find _any_ instance or class method,
         respectively.  */
      else
        warning (0, "no %<%c%E%> method found",
                 (class_tree ? '+' : '-'),
                 sel_name);

      if (!warn_missing_methods)
        {
          warning_at (input_location, 
                      0, "(Messages without a matching method signature");
          warning_at (input_location, 
                      0, "will be assumed to return %<id%> and accept");
          warning_at (input_location, 
                      0, "%<...%> as arguments.)");
          warn_missing_methods = true;
        }
    }
  else
    {
      /* Warn if the method is deprecated, but not if the receiver is
         a generic 'id'.  'id' is used to cast an object to a generic
         object of an unspecified class; in that case, we'll use
         whatever method prototype we can find to get the method
         argument and return types, but it is not appropriate to
         produce deprecation warnings since we don't know the class
         that the object will be of at runtime.  The @interface(s) for
         that class may not even be available to the compiler right
         now, and it is perfectly possible that the method is marked
         as non-deprecated in such @interface(s).

         In practice this makes sense since casting an object to 'id'
         is often used precisely to turn off warnings associated with
         the object being of a particular class.  */
      if (TREE_DEPRECATED (method_prototype)  &&  rtype != NULL_TREE)
        warn_deprecated_use (method_prototype, NULL_TREE);
    }


  /* Save the selector name for printing error messages.  */
  current_objc_message_selector = sel_name;

  /* Build the parameters list for looking up the method.
     These are the object itself and the selector.  */

  if (flag_typed_selectors)
    selector = build_typed_selector_reference (input_location,
                                               sel_name, method_prototype);
  else
    selector = build_selector_reference (input_location, sel_name);

  retval = build_objc_method_call (input_location, super, method_prototype,
                                   receiver,
                                   selector, method_params);

  current_objc_message_selector = 0;

  return retval;
}
\f
/* Build a tree expression to send OBJECT the operation SELECTOR,
   looking up the method on object LOOKUP_OBJECT (often same as OBJECT),
   assuming the method has prototype METHOD_PROTOTYPE.
   (That is an INSTANCE_METHOD_DECL or CLASS_METHOD_DECL.)
   LOC is the location of the expression to build.
   Use METHOD_PARAMS as list of args to pass to the method.
   If SUPER_FLAG is nonzero, we look up the superclass's method.  */

static tree
build_objc_method_call (location_t loc, int super_flag, tree method_prototype,
                        tree lookup_object, tree selector,
                        tree method_params)
{
  tree sender = (super_flag ? umsg_super_decl :
                 (!flag_next_runtime || flag_nil_receivers
                  ? (flag_objc_direct_dispatch
                     ? umsg_fast_decl
                     : umsg_decl)
                  : umsg_nonnil_decl));
  tree rcv_p = (super_flag ? objc_super_type : objc_object_type);
  VEC(tree, gc) *parms = NULL;
  unsigned nparm = (method_params ? list_length (method_params) : 0);

  /* If a prototype for the method to be called exists, then cast
     the sender's return type and arguments to match that of the method.
     Otherwise, leave sender as is.  */
  tree ret_type
    = (method_prototype
       ? TREE_VALUE (TREE_TYPE (method_prototype))
       : objc_object_type);

  tree method_param_types = 
                get_arg_type_list (method_prototype, METHOD_REF, super_flag);
  tree ftype = build_function_type (ret_type, method_param_types);
  tree sender_cast;
  tree method, t;

  if (method_prototype && METHOD_TYPE_ATTRIBUTES (method_prototype))
    ftype = build_type_attribute_variant (ftype, 
                                          METHOD_TYPE_ATTRIBUTES 
                                          (method_prototype));

  sender_cast = build_pointer_type (ftype);

  lookup_object = build_c_cast (loc, rcv_p, lookup_object);

  /* Use SAVE_EXPR to avoid evaluating the receiver twice.  */
  lookup_object = save_expr (lookup_object);

  /* Param list + 2 slots for object and selector.  */
  parms = VEC_alloc (tree, gc, nparm + 2);

  if (flag_next_runtime)
    {
      /* If we are returning a struct in memory, and the address
         of that memory location is passed as a hidden first
         argument, then change which messenger entry point this
         expr will call.  NB: Note that sender_cast remains
         unchanged (it already has a struct return type).  */
      if (!targetm.calls.struct_value_rtx (0, 0)
          && (TREE_CODE (ret_type) == RECORD_TYPE
              || TREE_CODE (ret_type) == UNION_TYPE)
          && targetm.calls.return_in_memory (ret_type, 0))
        sender = (super_flag ? umsg_super_stret_decl :
                flag_nil_receivers ? umsg_stret_decl : umsg_nonnil_stret_decl);

      method = build_fold_addr_expr_loc (input_location, sender);
      /* Pass the object to the method.  */
      VEC_quick_push (tree, parms, lookup_object);
    }
  else
    {
      /* This is the portable (GNU) way.  */
      /* First, call the lookup function to get a pointer to the method,
         then cast the pointer, then call it with the method arguments.  */
      VEC(tree, gc) *tv = VEC_alloc (tree, gc, 2);
      VEC_quick_push (tree, tv, lookup_object);
      VEC_quick_push (tree, tv, selector);
      method = build_function_call_vec (loc, sender, tv, NULL);
      VEC_free (tree, gc, tv);

      /* Pass the appropriate object to the method.  */
      VEC_quick_push (tree, parms, (super_flag ? self_decl : lookup_object));
    }

  /* Pass the selector to the method.  */
  VEC_quick_push (tree, parms, selector);
  /* Now append the remainder of the parms.  */
  if (nparm)
    for (; method_params; method_params = TREE_CHAIN (method_params))
      VEC_quick_push (tree, parms, TREE_VALUE (method_params));

  /* Build an obj_type_ref, with the correct cast for the method call.  */
  t = build3 (OBJ_TYPE_REF, sender_cast, method, 
                            lookup_object, size_zero_node);
  t = build_function_call_vec (loc, t, parms, NULL);\
  VEC_free (tree, gc, parms);
  return t;
}

static void
build_protocol_reference (tree p)
{
  tree decl;
  const char *proto_name;

  /* static struct _objc_protocol _OBJC_PROTOCOL_<mumble>; */

  proto_name = synth_id_with_class_suffix ("_OBJC_PROTOCOL", p);
  decl = start_var_decl (objc_protocol_template, proto_name);

  PROTOCOL_FORWARD_DECL (p) = decl;
}

/* This function is called by the parser when (and only when) a
   @protocol() expression is found, in order to compile it.  */
tree
objc_build_protocol_expr (tree protoname)
{
  tree expr;
  tree p = lookup_protocol (protoname);

  if (!p)
    {
      error ("cannot find protocol declaration for %qE",
             protoname);
      return error_mark_node;
    }

  if (!PROTOCOL_FORWARD_DECL (p))
    build_protocol_reference (p);

  expr = build_unary_op (input_location, 
                         ADDR_EXPR, PROTOCOL_FORWARD_DECL (p), 0);

  /* ??? Ideally we'd build the reference with objc_protocol_type directly,
     if we have it, rather than converting it here.  */
  expr = convert (objc_protocol_type, expr);

  /* The @protocol() expression is being compiled into a pointer to a
     statically allocated instance of the Protocol class.  To become
     usable at runtime, the 'isa' pointer of the instance need to be
     fixed up at runtime by the runtime library, to point to the
     actual 'Protocol' class.  */

  /* For the GNU runtime, put the static Protocol instance in the list
     of statically allocated instances, so that we make sure that its
     'isa' pointer is fixed up at runtime by the GNU runtime library
     to point to the Protocol class (at runtime, when loading the
     module, the GNU runtime library loops on the statically allocated
     instances (as found in the defs field in objc_symtab) and fixups
     all the 'isa' pointers of those objects).  */
  if (! flag_next_runtime)
    {
      /* This type is a struct containing the fields of a Protocol
        object.  (Cfr. objc_protocol_type instead is the type of a pointer
        to such a struct).  */
      tree protocol_struct_type = xref_tag
       (RECORD_TYPE, get_identifier (PROTOCOL_OBJECT_CLASS_NAME));
      tree *chain;

      /* Look for the list of Protocol statically allocated instances
        to fixup at runtime.  Create a new list to hold Protocol
        statically allocated instances, if the list is not found.  At
        present there is only another list, holding NSConstantString
        static instances to be fixed up at runtime.  */
      for (chain = &objc_static_instances;
           *chain && TREE_VALUE (*chain) != protocol_struct_type;
           chain = &TREE_CHAIN (*chain));
      if (!*chain)
        {
         *chain = tree_cons (NULL_TREE, protocol_struct_type, NULL_TREE);
         add_objc_string (OBJC_TYPE_NAME (protocol_struct_type),
                          class_names);
       }

      /* Add this statically allocated instance to the Protocol list.  */
      TREE_PURPOSE (*chain) = tree_cons (NULL_TREE,
                                         PROTOCOL_FORWARD_DECL (p),
                                         TREE_PURPOSE (*chain));
    }


  return expr;
}

/* This function is called by the parser when a @selector() expression
   is found, in order to compile it.  It is only called by the parser
   and only to compile a @selector().  LOC is the location of the
   @selector.  */
tree
objc_build_selector_expr (location_t loc, tree selnamelist)
{
  tree selname;

  /* Obtain the full selector name.  */
  switch (TREE_CODE (selnamelist))
    {
    case IDENTIFIER_NODE:
      /* A unary selector.  */
      selname = selnamelist;
      break;
    case TREE_LIST:
      selname = build_keyword_selector (selnamelist);
      break;
    default:
      gcc_unreachable ();
    }

  /* If we are required to check @selector() expressions as they
     are found, check that the selector has been declared.  */
  if (warn_undeclared_selector)
    {
      /* Look the selector up in the list of all known class and
         instance methods (up to this line) to check that the selector
         exists.  */
      hash hsh;

      /* First try with instance methods.  */
      hsh = hash_lookup (nst_method_hash_list, selname);

      /* If not found, try with class methods.  */
      if (!hsh)
        {
          hsh = hash_lookup (cls_method_hash_list, selname);
        }

      /* If still not found, print out a warning.  */
      if (!hsh)
        {
          warning (0, "undeclared selector %qE", selname);
        }
    }


  if (flag_typed_selectors)
    return build_typed_selector_reference (loc, selname, 0);
  else
    return build_selector_reference (loc, selname);
}

/* This is used to implement @encode().  See gcc/doc/objc.texi,
   section '@encode'.  */
tree
objc_build_encode_expr (tree type)
{
  tree result;
  const char *string;

  encode_type (type, obstack_object_size (&util_obstack),
               OBJC_ENCODE_INLINE_DEFS);
  obstack_1grow (&util_obstack, 0);    /* null terminate string */
  string = XOBFINISH (&util_obstack, const char *);

  /* Synthesize a string that represents the encoded struct/union.  */
  result = my_build_string (strlen (string) + 1, string);
  obstack_free (&util_obstack, util_firstobj);
  return result;
}

static tree
build_ivar_reference (tree id)
{
  if (TREE_CODE (objc_method_context) == CLASS_METHOD_DECL)
    {
      /* Historically, a class method that produced objects (factory
         method) would assign `self' to the instance that it
         allocated.  This would effectively turn the class method into
         an instance method.  Following this assignment, the instance
         variables could be accessed.  That practice, while safe,
         violates the simple rule that a class method should not refer
         to an instance variable.  It's better to catch the cases
         where this is done unknowingly than to support the above
         paradigm.  */
      warning (0, "instance variable %qE accessed in class method",
               id);
      self_decl = convert (objc_instance_type, self_decl); /* cast */
    }

  return objc_build_component_ref (build_indirect_ref (input_location,
                                                       self_decl, RO_ARROW),
                                   id);
}
\f
/* Compute a hash value for a given method SEL_NAME.  */

static size_t
hash_func (tree sel_name)
{
  const unsigned char *s
    = (const unsigned char *)IDENTIFIER_POINTER (sel_name);
  size_t h = 0;

  while (*s)
    h = h * 67 + *s++ - 113;
  return h;
}

static void
hash_init (void)
{
  nst_method_hash_list = ggc_alloc_cleared_vec_hash (SIZEHASHTABLE);
  cls_method_hash_list = ggc_alloc_cleared_vec_hash (SIZEHASHTABLE);

  cls_name_hash_list = ggc_alloc_cleared_vec_hash (SIZEHASHTABLE);
  als_name_hash_list = ggc_alloc_cleared_vec_hash (SIZEHASHTABLE);

  /* Initialize the hash table used to hold the constant string objects.  */
  string_htab = htab_create_ggc (31, string_hash,
                                   string_eq, NULL);
}

/* This routine adds sel_name to the hash list. sel_name  is a class or alias
   name for the class. If alias name, then value is its underlying class.
   If class, the value is NULL_TREE. */

static void
hash_class_name_enter (hash *hashlist, tree sel_name, tree value)
{
  hash obj;
  int slot = hash_func (sel_name) % SIZEHASHTABLE;

  obj = ggc_alloc_hashed_entry ();
  if (value != NULL_TREE)
    {
      /* Save the underlying class for the 'alias' in the hash table */
      attr obj_attr = ggc_alloc_hashed_attribute ();
      obj_attr->value = value;
      obj->list = obj_attr;
    }
  else
    obj->list = 0;
  obj->next = hashlist[slot];
  obj->key = sel_name;

  hashlist[slot] = obj;         /* append to front */

}

/*
   Searches in the hash table looking for a match for class or alias name.
*/

static hash
hash_class_name_lookup (hash *hashlist, tree sel_name)
{
  hash target;

  target = hashlist[hash_func (sel_name) % SIZEHASHTABLE];

  while (target)
    {
      if (sel_name == target->key)
        return target;

      target = target->next;
    }
  return 0;
}

/* WARNING!!!!  hash_enter is called with a method, and will peek
   inside to find its selector!  But hash_lookup is given a selector
   directly, and looks for the selector that's inside the found
   entry's key (method) for comparison.  */

static void
hash_enter (hash *hashlist, tree method)
{
  hash obj;
  int slot = hash_func (METHOD_SEL_NAME (method)) % SIZEHASHTABLE;

  obj = ggc_alloc_hashed_entry ();
  obj->list = 0;
  obj->next = hashlist[slot];
  obj->key = method;

  hashlist[slot] = obj;         /* append to front */
}

static hash
hash_lookup (hash *hashlist, tree sel_name)
{
  hash target;

  target = hashlist[hash_func (sel_name) % SIZEHASHTABLE];

  while (target)
    {
      if (sel_name == METHOD_SEL_NAME (target->key))
        return target;

      target = target->next;
    }
  return 0;
}

static void
hash_add_attr (hash entry, tree value)
{
  attr obj;

  obj = ggc_alloc_hashed_attribute ();
  obj->next = entry->list;
  obj->value = value;

  entry->list = obj;            /* append to front */
}
\f
static tree
lookup_method (tree mchain, tree method)
{
  tree key;

  if (TREE_CODE (method) == IDENTIFIER_NODE)
    key = method;
  else
    key = METHOD_SEL_NAME (method);

  while (mchain)
    {
      if (METHOD_SEL_NAME (mchain) == key)
        return mchain;

      mchain = DECL_CHAIN (mchain);
    }
  return NULL_TREE;
}

/* Look up a class (if OBJC_LOOKUP_CLASS is set in FLAGS) or instance
   method in INTERFACE, along with any categories and protocols
   attached thereto.  If method is not found, and the
   OBJC_LOOKUP_NO_SUPER is _not_ set in FLAGS, recursively examine the
   INTERFACE's superclass.  If OBJC_LOOKUP_CLASS is set,
   OBJC_LOOKUP_NO_SUPER is clear, and no suitable class method could
   be found in INTERFACE or any of its superclasses, look for an
   _instance_ method of the same name in the root class as a last
   resort.  This behaviour can be turned off by using
   OBJC_LOOKUP_NO_INSTANCE_METHODS_OF_ROOT_CLASS.

   If a suitable method cannot be found, return NULL_TREE.  */

static tree
lookup_method_static (tree interface, tree ident, int flags)
{
  tree meth = NULL_TREE, root_inter = NULL_TREE;
  tree inter = interface;
  int is_class = (flags & OBJC_LOOKUP_CLASS);
  int no_superclasses = (flags & OBJC_LOOKUP_NO_SUPER);
  int no_instance_methods_of_root_class = (flags & OBJC_LOOKUP_NO_INSTANCE_METHODS_OF_ROOT_CLASS);

  while (inter)
    {
      tree chain = is_class ? CLASS_CLS_METHODS (inter) : CLASS_NST_METHODS (inter);
      tree category = inter;

      /* First, look up the method in the class itself.  */
      if ((meth = lookup_method (chain, ident)))
        return meth;

      /* Failing that, look for the method in each category of the class.  */
      while ((category = CLASS_CATEGORY_LIST (category)))
        {
          chain = is_class ? CLASS_CLS_METHODS (category) : CLASS_NST_METHODS (category);

          /* Check directly in each category.  */
          if ((meth = lookup_method (chain, ident)))
            return meth;

          /* Failing that, check in each category's protocols.  */
          if (CLASS_PROTOCOL_LIST (category))
            {
              if ((meth = (lookup_method_in_protocol_list
                           (CLASS_PROTOCOL_LIST (category), ident, is_class))))
                return meth;
            }
        }

      /* If not found in categories, check in protocols of the main class.  */
      if (CLASS_PROTOCOL_LIST (inter))
        {
          if ((meth = (lookup_method_in_protocol_list
                       (CLASS_PROTOCOL_LIST (inter), ident, is_class))))
            return meth;
        }

      /* If we were instructed not to look in superclasses, don't.  */
      if (no_superclasses)
        return NULL_TREE;

      /* Failing that, climb up the inheritance hierarchy.  */
      root_inter = inter;
      inter = lookup_interface (CLASS_SUPER_NAME (inter));
    }
  while (inter);

  if (is_class && !no_instance_methods_of_root_class)
    {
      /* If no class (factory) method was found, check if an _instance_
         method of the same name exists in the root class.  This is what
         the Objective-C runtime will do.  */
      return lookup_method_static (root_inter, ident, 0);
    }
  else
    {
      /* If an instance method was not found, return 0.  */      
      return NULL_TREE;
    }
}

/* Add the method to the hash list if it doesn't contain an identical
   method already. */

static void
add_method_to_hash_list (hash *hash_list, tree method)
{
  hash hsh;

  if (!(hsh = hash_lookup (hash_list, METHOD_SEL_NAME (method))))
    {
      /* Install on a global chain.  */
      hash_enter (hash_list, method);
    }
  else
    {
      /* Check types against those; if different, add to a list.  */
      attr loop;
      int already_there = comp_proto_with_proto (method, hsh->key, 1);
      for (loop = hsh->list; !already_there && loop; loop = loop->next)
        already_there |= comp_proto_with_proto (method, loop->value, 1);
      if (!already_there)
        hash_add_attr (hsh, method);
    }
}

static tree
objc_add_method (tree klass, tree method, int is_class, bool is_optional)
{
  tree mth;

  /* @optional methods are added to protocol's OPTIONAL list */
  if (is_optional)
    {
      gcc_assert (TREE_CODE (klass) == PROTOCOL_INTERFACE_TYPE);
      if (!(mth = lookup_method (is_class
                                ? PROTOCOL_OPTIONAL_CLS_METHODS (klass)
                                : PROTOCOL_OPTIONAL_NST_METHODS (klass), 
                                                                method)))
        {
          if (is_class)
            {
              TREE_CHAIN (method) = PROTOCOL_OPTIONAL_CLS_METHODS (klass);
              PROTOCOL_OPTIONAL_CLS_METHODS (klass) = method;
            }
          else
            {
              TREE_CHAIN (method) = PROTOCOL_OPTIONAL_NST_METHODS (klass);
              PROTOCOL_OPTIONAL_NST_METHODS (klass) = method;
            }
        }
    }
  else if (!(mth = lookup_method (is_class
                             ? CLASS_CLS_METHODS (klass)
                             : CLASS_NST_METHODS (klass), method)))
    {
      /* put method on list in reverse order */
      if (is_class)
        {
          DECL_CHAIN (method) = CLASS_CLS_METHODS (klass);
          CLASS_CLS_METHODS (klass) = method;
        }
      else
        {
          DECL_CHAIN (method) = CLASS_NST_METHODS (klass);
          CLASS_NST_METHODS (klass) = method;
        }
    }
  else
    {
      /* When processing an @interface for a class or category, give hard
         errors on methods with identical selectors but differing argument
         and/or return types. We do not do this for @implementations, because
         C/C++ will do it for us (i.e., there will be duplicate function
         definition errors).  */
      if ((TREE_CODE (klass) == CLASS_INTERFACE_TYPE
           || TREE_CODE (klass) == CATEGORY_INTERFACE_TYPE)
          && !comp_proto_with_proto (method, mth, 1))
        error ("duplicate declaration of method %<%c%E%>",
                is_class ? '+' : '-',
                METHOD_SEL_NAME (mth));
    }

  if (is_class)
    add_method_to_hash_list (cls_method_hash_list, method);
  else
    {
      add_method_to_hash_list (nst_method_hash_list, method);

      /* Instance methods in root classes (and categories thereof)
         may act as class methods as a last resort.  We also add
         instance methods listed in @protocol declarations to
         the class hash table, on the assumption that @protocols
         may be adopted by root classes or categories.  */
      if (TREE_CODE (klass) == CATEGORY_INTERFACE_TYPE
          || TREE_CODE (klass) == CATEGORY_IMPLEMENTATION_TYPE)
        klass = lookup_interface (CLASS_NAME (klass));

      if (TREE_CODE (klass) == PROTOCOL_INTERFACE_TYPE
          || !CLASS_SUPER_NAME (klass))
        add_method_to_hash_list (cls_method_hash_list, method);
    }

  return method;
}

static tree
add_class (tree class_name, tree name)
{
  struct interface_tuple **slot;

  /* Put interfaces on list in reverse order.  */
  TREE_CHAIN (class_name) = interface_chain;
  interface_chain = class_name;

  if (interface_htab == NULL)
    interface_htab = htab_create_ggc (31, hash_interface, eq_interface, NULL);
  slot = (struct interface_tuple **)
    htab_find_slot_with_hash (interface_htab, name,
                              IDENTIFIER_HASH_VALUE (name),
                              INSERT);
  if (!*slot)
    {
      *slot = ggc_alloc_cleared_interface_tuple ();
      (*slot)->id = name;
    }
  (*slot)->class_name = class_name;

  return interface_chain;
}

static void
add_category (tree klass, tree category)
{
  /* Put categories on list in reverse order.  */
  tree cat = lookup_category (klass, CLASS_SUPER_NAME (category));

  if (cat)
    {
      warning (0, "duplicate interface declaration for category %<%E(%E)%>",
               CLASS_NAME (klass),
               CLASS_SUPER_NAME (category));
    }
  else
    {
      CLASS_CATEGORY_LIST (category) = CLASS_CATEGORY_LIST (klass);
      CLASS_CATEGORY_LIST (klass) = category;
    }
}

/* Called after parsing each instance variable declaration. Necessary to
   preserve typedefs and implement public/private...

   VISIBILITY is 1 for public, 0 for protected, and 2 for private.  */

static tree
add_instance_variable (tree klass, objc_ivar_visibility_kind visibility, 
                       tree field_decl)
{
  tree field_type = TREE_TYPE (field_decl);
  const char *ivar_name = DECL_NAME (field_decl)
                          ? identifier_to_locale (IDENTIFIER_POINTER (DECL_NAME (field_decl)))
                          : _("<unnamed>");

#ifdef OBJCPLUS
  if (TREE_CODE (field_type) == REFERENCE_TYPE)
    {
      error ("illegal reference type specified for instance variable %qs",
             ivar_name);
      /* Return class as is without adding this ivar.  */
      return klass;
    }
#endif

  if (field_type == error_mark_node || !TYPE_SIZE (field_type)
      || TYPE_SIZE (field_type) == error_mark_node)
      /* 'type[0]' is allowed, but 'type[]' is not! */
    {
      error ("instance variable %qs has unknown size", ivar_name);
      /* Return class as is without adding this ivar.  */
      return klass;
    }

#ifdef OBJCPLUS
  /* Check if the ivar being added has a non-POD C++ type.   If so, we will
     need to either (1) warn the user about it or (2) generate suitable
     constructor/destructor call from '- .cxx_construct' or '- .cxx_destruct'
     methods (if '-fobjc-call-cxx-cdtors' was specified).  */
  if (MAYBE_CLASS_TYPE_P (field_type)
      && (TYPE_NEEDS_CONSTRUCTING (field_type)
          || TYPE_HAS_NONTRIVIAL_DESTRUCTOR (field_type)
          || TYPE_POLYMORPHIC_P (field_type)))
    {
      tree type_name = OBJC_TYPE_NAME (field_type);

      if (flag_objc_call_cxx_cdtors)
        {
          /* Since the ObjC runtime will be calling the constructors and
             destructors for us, the only thing we can't handle is the lack
             of a default constructor.  */
          if (TYPE_NEEDS_CONSTRUCTING (field_type)
              && !TYPE_HAS_DEFAULT_CONSTRUCTOR (field_type))
            {
              warning (0, "type %qE has no default constructor to call",
                       type_name);

              /* If we cannot call a constructor, we should also avoid
                 calling the destructor, for symmetry.  */
              if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (field_type))
                warning (0, "destructor for %qE shall not be run either",
                         type_name);
            }
        }
      else
        {
          static bool warn_cxx_ivars = false;

          if (TYPE_POLYMORPHIC_P (field_type))
            {
              /* Vtable pointers are Real Bad(tm), since Obj-C cannot
                 initialize them.  */
              error ("type %qE has virtual member functions", type_name);
              error ("illegal aggregate type %qE specified "
                     "for instance variable %qs",
                     type_name, ivar_name);
              /* Return class as is without adding this ivar.  */
              return klass;
            }

          /* User-defined constructors and destructors are not known to Obj-C
             and hence will not be called.  This may or may not be a problem. */
          if (TYPE_NEEDS_CONSTRUCTING (field_type))
            warning (0, "type %qE has a user-defined constructor", type_name);
          if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (field_type))
            warning (0, "type %qE has a user-defined destructor", type_name);

          if (!warn_cxx_ivars)
            {
              warning (0, "C++ constructors and destructors will not "
                       "be invoked for Objective-C fields");
              warn_cxx_ivars = true;
            }
        }
    }
#endif

  /* Overload the public attribute, it is not used for FIELD_DECLs.  */
  switch (visibility)
    {
    case OBJC_IVAR_VIS_PROTECTED:
      TREE_PUBLIC (field_decl) = 0;
      TREE_PRIVATE (field_decl) = 0;
      TREE_PROTECTED (field_decl) = 1;
      break;

    case OBJC_IVAR_VIS_PACKAGE:
    /* TODO: Implement the package variant.  */
    case OBJC_IVAR_VIS_PUBLIC:
      TREE_PUBLIC (field_decl) = 1;
      TREE_PRIVATE (field_decl) = 0;
      TREE_PROTECTED (field_decl) = 0;
      break;

    case OBJC_IVAR_VIS_PRIVATE:
      TREE_PUBLIC (field_decl) = 0;
      TREE_PRIVATE (field_decl) = 1;
      TREE_PROTECTED (field_decl) = 0;
      break;

    }

  CLASS_RAW_IVARS (klass) = chainon (CLASS_RAW_IVARS (klass), field_decl);

  return klass;
}
\f

static tree
is_ivar (tree decl_chain, tree ident)
{
  for ( ; decl_chain; decl_chain = DECL_CHAIN (decl_chain))
    if (DECL_NAME (decl_chain) == ident)
      return decl_chain;
  return NULL_TREE;
}

/* True if the ivar is private and we are not in its implementation.  */

static int
is_private (tree decl)
{
  return (TREE_PRIVATE (decl)
          && ! is_ivar (CLASS_IVARS (implementation_template),
                        DECL_NAME (decl)));
}

/* We have an instance variable reference;, check to see if it is public.  */

int
objc_is_public (tree expr, tree identifier)
{
  tree basetype, decl;

#ifdef OBJCPLUS
  if (processing_template_decl)
    return 1;
#endif

  if (TREE_TYPE (expr) == error_mark_node)
    return 1;

  basetype = TYPE_MAIN_VARIANT (TREE_TYPE (expr));

  if (basetype && TREE_CODE (basetype) == RECORD_TYPE)
    {
      if (TYPE_HAS_OBJC_INFO (basetype) && TYPE_OBJC_INTERFACE (basetype))
        {
          tree klass = lookup_interface (OBJC_TYPE_NAME (basetype));

          if (!klass)
            {
              error ("cannot find interface declaration for %qE",
                     OBJC_TYPE_NAME (basetype));
              return 0;
            }

          if ((decl = is_ivar (get_class_ivars (klass, true), identifier)))
            {
              if (TREE_PUBLIC (decl))
                return 1;

              /* Important difference between the Stepstone translator:
                 all instance variables should be public within the context
                 of the implementation.  */
              if (objc_implementation_context
                 && ((TREE_CODE (objc_implementation_context)
                      == CLASS_IMPLEMENTATION_TYPE)
                     || (TREE_CODE (objc_implementation_context)
                         == CATEGORY_IMPLEMENTATION_TYPE)))
                {
                  tree curtype = TYPE_MAIN_VARIANT
                                 (CLASS_STATIC_TEMPLATE
                                  (implementation_template));

                  if (basetype == curtype
                      || DERIVED_FROM_P (basetype, curtype))
                    {
                      int priv = is_private (decl);

                      if (priv)
                        error ("instance variable %qE is declared private",
                               DECL_NAME (decl));

                      return !priv;
                    }
                }

              /* The 2.95.2 compiler sometimes allowed C functions to access
                 non-@public ivars.  We will let this slide for now...  */
              if (!objc_method_context)
              {
                warning (0, "instance variable %qE is %s; "
                         "this will be a hard error in the future",
                         identifier,
                         TREE_PRIVATE (decl) ? "@private" : "@protected");
                return 1;
              }

              error ("instance variable %qE is declared %s",
                     identifier,
                     TREE_PRIVATE (decl) ? "private" : "protected");
              return 0;
            }
        }
    }

  return 1;
}
\f
/* Make sure all methods in CHAIN (a list of method declarations from
   an @interface or a @protocol) are in IMPLEMENTATION (the
   implementation context).  This is used to check for example that
   all methods declared in an @interface were implemented in an
   @implementation.

   Some special methods (property setters/getters) are special and if
   they are not found in IMPLEMENTATION, we look them up in its
   superclasses.  */

static int
check_methods (tree chain, tree implementation, int mtype)
{
  int first = 1;
  tree list;

  if (mtype == (int)'+')
    list = CLASS_CLS_METHODS (implementation);
  else
    list = CLASS_NST_METHODS (implementation);

  while (chain)
    {
      /* If the method is associated with a dynamic property, then it
         is Ok not to have the method implementation, as it will be
         generated dynamically at runtime.  To decide if the method is
         associated with a @dynamic property, we search the list of
         @synthesize and @dynamic for this implementation, and look
         for any @dynamic property with the same setter or getter name
         as this method.  */
      tree x;
      for (x = IMPL_PROPERTY_DECL (implementation); x; x = TREE_CHAIN (x))
        if (PROPERTY_DYNAMIC (x)
            && (PROPERTY_GETTER_NAME (x) == METHOD_SEL_NAME (chain)
                || PROPERTY_SETTER_NAME (x) == METHOD_SEL_NAME (chain)))
          break;
      
      if (x != NULL_TREE)
        {
          chain = TREE_CHAIN (chain); /* next method...  */
          continue;
        }

      if (!lookup_method (list, chain))
        {
          /* If the method is a property setter/getter, we'll still
             allow it to be missing if it is implemented by
             'interface' or any of its superclasses.  */
          tree property = METHOD_PROPERTY_CONTEXT (chain);
          if (property)
            {
              /* Note that since this is a property getter/setter, it
                 is obviously an instance method.  */
              tree interface = NULL_TREE;

              /* For a category, first check the main class
                 @interface.  */
              if (TREE_CODE (implementation) == CATEGORY_IMPLEMENTATION_TYPE)
                {
                  interface = lookup_interface (CLASS_NAME (implementation));

                  /* If the method is found in the main class, it's Ok.  */
                  if (lookup_method (CLASS_NST_METHODS (interface), chain))
                    {
                      chain = DECL_CHAIN (chain);
                      continue;               
                    }

                  /* Else, get the superclass.  */
                  if (CLASS_SUPER_NAME (interface))
                    interface = lookup_interface (CLASS_SUPER_NAME (interface));
                  else
                    interface = NULL_TREE;
                }

              /* Get the superclass for classes.  */
              if (TREE_CODE (implementation) == CLASS_IMPLEMENTATION_TYPE)
                {
                  if (CLASS_SUPER_NAME (implementation))
                    interface = lookup_interface (CLASS_SUPER_NAME (implementation));
                  else
                    interface = NULL_TREE;
                }

              /* Now, interface is the superclass, if any; go check it.  */
              if (interface)
                {
                  if (lookup_method_static (interface, chain, 0))
                    {
                      chain = DECL_CHAIN (chain);
                      continue;
                    }
                }
              /* Else, fall through - warn.  */
            }
          if (first)
            {
              switch (TREE_CODE (implementation))
                {
                case CLASS_IMPLEMENTATION_TYPE:
                  warning (0, "incomplete implementation of class %qE",
                           CLASS_NAME (implementation));
                  break;
                case CATEGORY_IMPLEMENTATION_TYPE:
                  warning (0, "incomplete implementation of category %qE",
                           CLASS_SUPER_NAME (implementation));
                  break;
                default:
                  gcc_unreachable ();
                }
              first = 0;
            }

          warning (0, "method definition for %<%c%E%> not found",
                   mtype, METHOD_SEL_NAME (chain));
        }

      chain = DECL_CHAIN (chain);
    }

    return first;
}

/* Check if KLASS, or its superclasses, explicitly conforms to PROTOCOL.  */

static int
conforms_to_protocol (tree klass, tree protocol)
{
   if (TREE_CODE (protocol) == PROTOCOL_INTERFACE_TYPE)
     {
       tree p = CLASS_PROTOCOL_LIST (klass);
       while (p && TREE_VALUE (p) != protocol)
         p = TREE_CHAIN (p);

       if (!p)
         {
           tree super = (CLASS_SUPER_NAME (klass)
                         ? lookup_interface (CLASS_SUPER_NAME (klass))
                         : NULL_TREE);
           int tmp = super ? conforms_to_protocol (super, protocol) : 0;
           if (!tmp)
             return 0;
         }
     }

   return 1;
}

/* Make sure all methods in CHAIN are accessible as MTYPE methods in
   CONTEXT.  This is one of two mechanisms to check protocol integrity.  */

static int
check_methods_accessible (tree chain, tree context, int mtype)
{
  int first = 1;
  tree list;
  tree base_context = context;

  while (chain)
    {
      /* If the method is associated with a dynamic property, then it
         is Ok not to have the method implementation, as it will be
         generated dynamically at runtime.  Search for any @dynamic
         property with the same setter or getter name as this
         method.  TODO: Use a hashtable lookup.  */
      tree x;
      for (x = IMPL_PROPERTY_DECL (base_context); x; x = TREE_CHAIN (x))
        if (PROPERTY_DYNAMIC (x)
            && (PROPERTY_GETTER_NAME (x) == METHOD_SEL_NAME (chain)
                || PROPERTY_SETTER_NAME (x) == METHOD_SEL_NAME (chain)))
          break;
      
      if (x != NULL_TREE)
        {
          chain = TREE_CHAIN (chain); /* next method...  */
          continue;
        }       

      context = base_context;
      while (context)
        {
          if (mtype == '+')
            list = CLASS_CLS_METHODS (context);
          else
            list = CLASS_NST_METHODS (context);

          if (lookup_method (list, chain))
              break;

          switch (TREE_CODE (context))
            {
            case CLASS_IMPLEMENTATION_TYPE:
            case CLASS_INTERFACE_TYPE:
              context = (CLASS_SUPER_NAME (context)
                         ? lookup_interface (CLASS_SUPER_NAME (context))
                         : NULL_TREE);
              break;
            case CATEGORY_IMPLEMENTATION_TYPE:
            case CATEGORY_INTERFACE_TYPE:
              context = (CLASS_NAME (context)
                         ? lookup_interface (CLASS_NAME (context))
                         : NULL_TREE);
              break;
            default:
              gcc_unreachable ();
            }
        }

      if (context == NULL_TREE)
        {
          if (first)
            {
              switch (TREE_CODE (objc_implementation_context))
                {
                case CLASS_IMPLEMENTATION_TYPE:
                  warning (0, "incomplete implementation of class %qE",
                           CLASS_NAME (objc_implementation_context));
                  break;
                case CATEGORY_IMPLEMENTATION_TYPE:
                  warning (0, "incomplete implementation of category %qE",
                           CLASS_SUPER_NAME (objc_implementation_context));
                  break;
                default:
                  gcc_unreachable ();
                }
              first = 0;
            }
          warning (0, "method definition for %<%c%E%> not found",
                   mtype, METHOD_SEL_NAME (chain));
        }

      chain = TREE_CHAIN (chain); /* next method...  */
    }
  return first;
}

/* Check whether the current interface (accessible via
   'objc_implementation_context') actually implements protocol P, along
   with any protocols that P inherits.  */

static void
check_protocol (tree p, const char *type, tree name)
{
  if (TREE_CODE (p) == PROTOCOL_INTERFACE_TYPE)
    {
      int f1, f2;

      /* Ensure that all protocols have bodies!  */
      if (warn_protocol)
        {
          f1 = check_methods (PROTOCOL_CLS_METHODS (p),
                              objc_implementation_context,
                              '+');
          f2 = check_methods (PROTOCOL_NST_METHODS (p),
                              objc_implementation_context,
                              '-');
        }
      else
        {
          f1 = check_methods_accessible (PROTOCOL_CLS_METHODS (p),
                                         objc_implementation_context,
                                         '+');
          f2 = check_methods_accessible (PROTOCOL_NST_METHODS (p),
                                         objc_implementation_context,
                                         '-');
        }

      if (!f1 || !f2)
        warning (0, "%s %qE does not fully implement the %qE protocol",
                 type, name, PROTOCOL_NAME (p));
    }

  /* Check protocols recursively.  */
  if (PROTOCOL_LIST (p))
    {
      tree subs = PROTOCOL_LIST (p);
      tree super_class =
        lookup_interface (CLASS_SUPER_NAME (implementation_template));

      while (subs)
        {
          tree sub = TREE_VALUE (subs);

          /* If the superclass does not conform to the protocols
             inherited by P, then we must!  */
          if (!super_class || !conforms_to_protocol (super_class, sub))
            check_protocol (sub, type, name);
          subs = TREE_CHAIN (subs);
        }
    }
}

/* Check whether the current interface (accessible via
   'objc_implementation_context') actually implements the protocols listed
   in PROTO_LIST.  */

static void
check_protocols (tree proto_list, const char *type, tree name)
{
  for ( ; proto_list; proto_list = TREE_CHAIN (proto_list))
    {
      tree p = TREE_VALUE (proto_list);

      check_protocol (p, type, name);
    }
}
\f
/* Make sure that the class CLASS_NAME is defined
   CODE says which kind of thing CLASS_NAME ought to be.
   It can be CLASS_INTERFACE_TYPE, CLASS_IMPLEMENTATION_TYPE,
   CATEGORY_INTERFACE_TYPE, or CATEGORY_IMPLEMENTATION_TYPE.  */

static tree
start_class (enum tree_code code, tree class_name, tree super_name,
             tree protocol_list)
{
  tree klass, decl;

#ifdef OBJCPLUS
  if (current_namespace != global_namespace) {
    error ("Objective-C declarations may only appear in global scope");
  }
#endif /* OBJCPLUS */

  if (objc_implementation_context)
    {
      warning (0, "%<@end%> missing in implementation context");
      finish_class (objc_implementation_context);
      objc_ivar_chain = NULL_TREE;
      objc_implementation_context = NULL_TREE;
    }

  klass = make_node (code);
  TYPE_LANG_SLOT_1 (klass) = make_tree_vec (CLASS_LANG_SLOT_ELTS);

  /* Check for existence of the super class, if one was specified.  Note
     that we must have seen an @interface, not just a @class.  If we
     are looking at a @compatibility_alias, traverse it first.  */
  if ((code == CLASS_INTERFACE_TYPE || code == CLASS_IMPLEMENTATION_TYPE)
      && super_name)
    {
      tree super = objc_is_class_name (super_name);

      if (!super || !lookup_interface (super))
        {
          error ("cannot find interface declaration for %qE, superclass of %qE",
                 super ? super : super_name,
                 class_name);
          super_name = NULL_TREE;
        }
      else
        super_name = super;
    }

  CLASS_NAME (klass) = class_name;
  CLASS_SUPER_NAME (klass) = super_name;
  CLASS_CLS_METHODS (klass) = NULL_TREE;

  if (! objc_is_class_name (class_name)
      && (decl = lookup_name (class_name)))
    {
      error ("%qE redeclared as different kind of symbol",
             class_name);
      error ("previous declaration of %q+D",
             decl);
    }

  switch (code)
    {
    case CLASS_IMPLEMENTATION_TYPE:
      {
        tree chain;
        
        for (chain = implemented_classes; chain; chain = TREE_CHAIN (chain))
          if (TREE_VALUE (chain) == class_name)
            {
              error ("reimplementation of class %qE",
                     class_name);
              return error_mark_node;
            }
        implemented_classes = tree_cons (NULL_TREE, class_name,
                                         implemented_classes);
      }

      /* Reset for multiple classes per file.  */
      method_slot = 0;

      objc_implementation_context = klass;

      /* Lookup the interface for this implementation.  */

      if (!(implementation_template = lookup_interface (class_name)))
        {
          warning (0, "cannot find interface declaration for %qE",
                   class_name);
          add_class (implementation_template = objc_implementation_context,
                     class_name);
        }

      /* If a super class has been specified in the implementation,
         insure it conforms to the one specified in the interface.  */

      if (super_name
          && (super_name != CLASS_SUPER_NAME (implementation_template)))
        {
          tree previous_name = CLASS_SUPER_NAME (implementation_template);
          error ("conflicting super class name %qE",
                 super_name);
          if (previous_name)
            error ("previous declaration of %qE", previous_name);
          else
            error ("previous declaration");
        }

      else if (! super_name)
        {
          CLASS_SUPER_NAME (objc_implementation_context)
            = CLASS_SUPER_NAME (implementation_template);
        }
      break;

    case CLASS_INTERFACE_TYPE:
      if (lookup_interface (class_name))
#ifdef OBJCPLUS
        error ("duplicate interface declaration for class %qE", class_name);
#else
        warning (0, "duplicate interface declaration for class %qE", class_name);
#endif
      else
        add_class (klass, class_name);
       
      if (protocol_list)
        CLASS_PROTOCOL_LIST (klass)
          = lookup_and_install_protocols (protocol_list);
      break;     

    case CATEGORY_INTERFACE_TYPE:
      {
        tree class_category_is_assoc_with;
        
        /* For a category, class_name is really the name of the class that
           the following set of methods will be associated with. We must
           find the interface so that can derive the objects template.  */
        if (!(class_category_is_assoc_with = lookup_interface (class_name)))
          {
            error ("cannot find interface declaration for %qE",
                   class_name);
            exit (FATAL_EXIT_CODE);
          }
        else
          add_category (class_category_is_assoc_with, klass);
        
        if (protocol_list)
          CLASS_PROTOCOL_LIST (klass)
            = lookup_and_install_protocols (protocol_list);
      }
      break;

    case CATEGORY_IMPLEMENTATION_TYPE:
      /* Reset for multiple classes per file.  */
      method_slot = 0;

      objc_implementation_context = klass;

      /* For a category, class_name is really the name of the class that
         the following set of methods will be associated with.  We must
         find the interface so that can derive the objects template.  */

      if (!(implementation_template = lookup_interface (class_name)))
        {
          error ("cannot find interface declaration for %qE",
                 class_name);
          exit (FATAL_EXIT_CODE);
        }
      break;
    default:
      gcc_unreachable ();
    }
  return klass;
}

static tree
continue_class (tree klass)
{
  switch (TREE_CODE (klass))
    {
    case CLASS_IMPLEMENTATION_TYPE:
    case CATEGORY_IMPLEMENTATION_TYPE:
      {
        struct imp_entry *imp_entry;

        /* Check consistency of the instance variables.  */

        if (CLASS_RAW_IVARS (klass))
          check_ivars (implementation_template, klass);
        
        /* code generation */
#ifdef OBJCPLUS
        push_lang_context (lang_name_c);
#endif
        build_private_template (implementation_template);
        uprivate_record = CLASS_STATIC_TEMPLATE (implementation_template);
        objc_instance_type = build_pointer_type (uprivate_record);

        imp_entry = ggc_alloc_imp_entry ();

        imp_entry->next = imp_list;
        imp_entry->imp_context = klass;
        imp_entry->imp_template = implementation_template;

        synth_forward_declarations ();
        imp_entry->class_decl = UOBJC_CLASS_decl;
        imp_entry->meta_decl = UOBJC_METACLASS_decl;
        imp_entry->has_cxx_cdtors = 0;

        /* Append to front and increment count.  */
        imp_list = imp_entry;
        if (TREE_CODE (klass) == CLASS_IMPLEMENTATION_TYPE)
          imp_count++;
        else
          cat_count++;
#ifdef OBJCPLUS
        pop_lang_context ();
#endif /* OBJCPLUS */
        
        return get_class_ivars (implementation_template, true);
        break;
      }
    case CLASS_INTERFACE_TYPE:
      {
#ifdef OBJCPLUS
        push_lang_context (lang_name_c);
#endif /* OBJCPLUS */
        objc_collecting_ivars = 1;
        build_private_template (klass);
        objc_collecting_ivars = 0;
#ifdef OBJCPLUS
        pop_lang_context ();
#endif /* OBJCPLUS */
        return NULL_TREE;
        break;
      }
    default:
      return error_mark_node;
    }
}

/* This routine builds name of the setter synthesized function. */
static char *
objc_build_property_setter_name (tree ident)
{
  /* TODO: Use alloca to allocate buffer of appropriate size.  */
  static char string[BUFSIZE];
  sprintf (string, "set%s:", IDENTIFIER_POINTER (ident));
  string[3] = TOUPPER (string[3]);
  return string;
}

/* This routine prepares the declarations of the property accessor
   helper functions (objc_getProperty(), etc) that are used when
   @synthesize is used.  */
static void 
build_objc_property_accessor_helpers (void)
{
  tree type;

  /* Declare the following function:
     id
     objc_getProperty (id self, SEL _cmd, 
                       ptrdiff_t offset, BOOL is_atomic);  */
  type = build_function_type_list (objc_object_type,
                                   objc_object_type,
                                   objc_selector_type,
                                   ptrdiff_type_node,
                                   boolean_type_node,
                                   NULL_TREE);
  objc_getProperty_decl = add_builtin_function ("objc_getProperty",
                                                type, 0, NOT_BUILT_IN,
                                                NULL, NULL_TREE);
  TREE_NOTHROW (objc_getProperty_decl) = 0;
  
  /* Declare the following function:
     void
     objc_setProperty (id self, SEL _cmd, 
                       ptrdiff_t offset, id new_value, 
                       BOOL is_atomic, BOOL should_copy);  */
  type = build_function_type_list (void_type_node,
                                   objc_object_type,
                                   objc_selector_type,
                                   ptrdiff_type_node,
                                   objc_object_type,
                                   boolean_type_node,
                                   boolean_type_node,
                                   NULL_TREE);
  objc_setProperty_decl = add_builtin_function ("objc_setProperty",
                                                type, 0, NOT_BUILT_IN,
                                                NULL, NULL_TREE);
  TREE_NOTHROW (objc_setProperty_decl) = 0;

  /* This is the type of all of the following functions
     (objc_copyStruct(), objc_getPropertyStruct() and
     objc_setPropertyStruct()).  */
  type = build_function_type_list (void_type_node,
                                   ptr_type_node,
                                   const_ptr_type_node,
                                   ptrdiff_type_node,       
                                   boolean_type_node,
                                   boolean_type_node,
                                   NULL_TREE);

  if (flag_next_runtime)
    {
      /* Declare the following function:
         void
         objc_copyStruct (void *destination, const void *source, 
                          ptrdiff_t size, BOOL is_atomic, BOOL has_strong);  */
      objc_copyStruct_decl = add_builtin_function ("objc_copyStruct",
                                                   type, 0, NOT_BUILT_IN,
                                                   NULL, NULL_TREE);
      TREE_NOTHROW (objc_copyStruct_decl) = 0;
      objc_getPropertyStruct_decl = NULL_TREE;
      objc_setPropertyStruct_decl = NULL_TREE;
    }
  else
    {
      objc_copyStruct_decl = NULL_TREE;

      /* Declare the following function:
         void
         objc_getPropertyStruct (void *destination, const void *source, 
                                 ptrdiff_t size, BOOL is_atomic, BOOL has_strong);  */
      objc_getPropertyStruct_decl = add_builtin_function ("objc_getPropertyStruct",
                                                          type, 0, NOT_BUILT_IN,
                                                          NULL, NULL_TREE);
      TREE_NOTHROW (objc_getPropertyStruct_decl) = 0;
      /* Declare the following function:
         void
         objc_setPropertyStruct (void *destination, const void *source, 
                                 ptrdiff_t size, BOOL is_atomic, BOOL has_strong);  */
      objc_setPropertyStruct_decl = add_builtin_function ("objc_setPropertyStruct",
                                                          type, 0, NOT_BUILT_IN,
                                                          NULL, NULL_TREE);
      TREE_NOTHROW (objc_setPropertyStruct_decl) = 0;
    }
}

/* This looks up an ivar in a class (including superclasses).  */
static tree
lookup_ivar (tree interface, tree instance_variable_name)
{
  while (interface)
    {
      tree decl_chain;
      
      for (decl_chain = CLASS_IVARS (interface); decl_chain; decl_chain = DECL_CHAIN (decl_chain))
        if (DECL_NAME (decl_chain) == instance_variable_name)
          return decl_chain;
      
      /* Not found.  Search superclass if any.  */
      if (CLASS_SUPER_NAME (interface))
        interface = lookup_interface (CLASS_SUPER_NAME (interface));
    }
  
  return NULL_TREE;
}

/* This routine synthesizes a 'getter' method.  This is only called
   for @synthesize properties.  */
static void
objc_synthesize_getter (tree klass, tree class_methods ATTRIBUTE_UNUSED, tree property)
{
  location_t location = DECL_SOURCE_LOCATION (property);
  tree fn, decl;
  tree body;
  tree ret_val;

  /* If user has implemented a getter with same name then do nothing.  */
  if (lookup_method (CLASS_NST_METHODS (objc_implementation_context),
                     PROPERTY_GETTER_NAME (property)))
    return;

  /* Find declaration of the property getter in the interface (or
     superclass, or protocol). There must be one.  */
  decl = lookup_method_static (klass, PROPERTY_GETTER_NAME (property), 0);

  /* If one not declared in the interface, this condition has already
     been reported as user error (because property was not declared in
     the interface).  */
  if (!decl)
    return;

  /* Adapt the 'decl'.  Use the source location of the @synthesize
     statement for error messages.  */
  decl = copy_node (decl);
  DECL_SOURCE_LOCATION (decl) = location;

  objc_start_method_definition (false /* is_class_method */, decl, NULL_TREE);
  body = c_begin_compound_stmt (true);

  /* Now we need to decide how we build the getter.  There are three
     cases:

     for 'copy' or 'retain' properties we need to use the
     objc_getProperty() accessor helper which knows about retain and
     copy.  It supports both 'nonatomic' and 'atomic' access.

     for 'nonatomic, assign' properties we can access the instance
     variable directly.  'nonatomic' means we don't have to use locks,
     and 'assign' means we don't have to worry about retain or copy.
     If you combine the two, it means we can just access the instance
     variable directly.

     for 'atomic, assign' properties we use objc_copyStruct() (for the
     next runtime) or objc_getPropertyStruct() (for the GNU runtime).  */
  switch (PROPERTY_ASSIGN_SEMANTICS (property))
    {
    case OBJC_PROPERTY_RETAIN:
    case OBJC_PROPERTY_COPY:
      {
        /* We build "return objc_getProperty (self, _cmd, offset, is_atomic);"  */
        tree cmd, ivar, offset, is_atomic;
        cmd = TREE_CHAIN (DECL_ARGUMENTS (current_function_decl));

        /* Find the ivar to compute the offset.  */
        ivar = lookup_ivar (klass, PROPERTY_IVAR_NAME (property));
        if (!ivar || is_private (ivar))
          {
            /* This should never happen.  */
            error_at (location,
                      "can not find instance variable associated with property");
            ret_val = error_mark_node;
            break;
          }
        offset = byte_position (ivar);

        if (PROPERTY_NONATOMIC (property))
          is_atomic = boolean_false_node;
        else
          is_atomic = boolean_true_node;

        ret_val = build_function_call
          (location,
           /* Function prototype.  */
           objc_getProperty_decl,
           /* Parameters.  */
           tree_cons    /* self */
           (NULL_TREE, self_decl,
            tree_cons   /* _cmd */
            (NULL_TREE, cmd,
             tree_cons  /* offset */
             (NULL_TREE, offset,
              tree_cons /* is_atomic */
              (NULL_TREE, is_atomic, NULL_TREE)))));
      }
      break;
    case OBJC_PROPERTY_ASSIGN:    
      if (PROPERTY_NONATOMIC (property))
        {
          /* We build "return self->PROPERTY_IVAR_NAME;"  */
          ret_val = objc_lookup_ivar (NULL_TREE, PROPERTY_IVAR_NAME (property));
          break;
        }
      else
        {
          /* We build
               <property type> __objc_property_temp;
               objc_getPropertyStruct (&__objc_property_temp,
                                       &(self->PROPERTY_IVAR_NAME),
                                       sizeof (type of self->PROPERTY_IVAR_NAME),
                                       is_atomic,
                                       false)
               return __objc_property_temp;

             For the NeXT runtime, we need to use objc_copyStruct
             instead of objc_getPropertyStruct.  */
          tree objc_property_temp_decl, function_decl, function_call;
          tree size_of, is_atomic;

          objc_property_temp_decl = objc_create_temporary_var (TREE_TYPE (property), "__objc_property_temp");
          DECL_SOURCE_LOCATION (objc_property_temp_decl) = location;
          objc_property_temp_decl = lang_hooks.decls.pushdecl (objc_property_temp_decl);

          /* sizeof (ivar type).  Since the ivar and the property have
             the same type, there is no need to lookup the ivar.  */
          size_of = c_sizeof_or_alignof_type (location, TREE_TYPE (property),
                                              true /* is_sizeof */,
                                              false /* complain */);
          
          if (PROPERTY_NONATOMIC (property))
            is_atomic = boolean_false_node;
          else
            is_atomic = boolean_true_node;
          
          if (flag_next_runtime)
            function_decl = objc_copyStruct_decl;
          else
            function_decl = objc_getPropertyStruct_decl;

          function_call = build_function_call
            (location,
             /* Function prototype.  */
             function_decl,
             /* Parameters.  */
             tree_cons /* &__objc_property_temp_decl */
             /* Warning: note that using build_fold_addr_expr_loc()
                here causes invalid code to be generated.  */
             (NULL_TREE, build_unary_op (location, ADDR_EXPR, objc_property_temp_decl, 0),
              tree_cons /* &(self->PROPERTY_IVAR_NAME); */
              (NULL_TREE, build_fold_addr_expr_loc (location, 
                                                    objc_lookup_ivar 
                                                    (NULL_TREE, PROPERTY_IVAR_NAME (property))),
               tree_cons /* sizeof (PROPERTY_IVAR) */
               (NULL_TREE, size_of,
                tree_cons /* is_atomic */
                (NULL_TREE, is_atomic,
                 /* TODO: This is currently ignored by the GNU
                    runtime, but what about the next one ? */
                 tree_cons /* has_strong */
                 (NULL_TREE, boolean_true_node, NULL_TREE))))));

          add_stmt (function_call);

          ret_val = objc_property_temp_decl;
        }
      break;
    default:
      gcc_unreachable ();
    }

  gcc_assert (ret_val);

#ifdef OBJCPLUS
  finish_return_stmt (ret_val);
#else
  c_finish_return (location, ret_val, NULL_TREE);
#endif

  add_stmt (c_end_compound_stmt (location, body, true));
  fn = current_function_decl;
#ifdef OBJCPLUS
  finish_function ();
#endif
  objc_finish_method_definition (fn);
}

/* This routine synthesizes a 'setter' method.  */

static void
objc_synthesize_setter (tree klass, tree class_methods ATTRIBUTE_UNUSED, tree property)
{
  location_t location = DECL_SOURCE_LOCATION (property);
  tree fn, decl;
  tree body;
  tree new_value, statement;

  /* If user has implemented a setter with same name then do nothing.  */
  if (lookup_method (CLASS_NST_METHODS (objc_implementation_context),
                     PROPERTY_SETTER_NAME (property)))
    return;

  /* Find declaration of the property setter in the interface (or
     superclass, or protocol). There must be one.  */
  decl = lookup_method_static (klass, PROPERTY_SETTER_NAME (property), 0);

  /* If one not declared in the interface, this condition has already
     been reported as user error (because property was not declared in
     the interface).  */
  if (!decl)
    return;

  /* Adapt the 'decl'.  Use the source location of the @synthesize
     statement for error messages.  */
  decl = copy_node (decl);
  DECL_SOURCE_LOCATION (decl) = DECL_SOURCE_LOCATION (property);

  objc_start_method_definition (false /* is_class_method */, decl, NULL_TREE);

  body = c_begin_compound_stmt (true);

  /* The 'new_value' is the only argument to the method, which is the
     3rd argument of the function, after self and _cmd.  We use twice
     TREE_CHAIN to move forward two arguments.  */
  new_value = TREE_CHAIN (TREE_CHAIN (DECL_ARGUMENTS (current_function_decl)));

  /* This would presumably happen if the user has specified a
     prototype for the setter that does not have an argument!  */
  if (new_value == NULL_TREE)
    {
      /* TODO: This should be caught much earlier than this.  */
      error_at (DECL_SOURCE_LOCATION (decl), "invalid setter, it must have one argument");
      /* Try to recover somehow.  */
      new_value = error_mark_node;
    }

  /* Now we need to decide how we build the setter.  There are three
     cases:

     for 'copy' or 'retain' properties we need to use the
     objc_setProperty() accessor helper which knows about retain and
     copy.  It supports both 'nonatomic' and 'atomic' access.

     for 'nonatomic, assign' properties we can access the instance
     variable directly.  'nonatomic' means we don't have to use locks,
     and 'assign' means we don't have to worry about retain or copy.
     If you combine the two, it means we can just access the instance
     variable directly.

     for 'atomic, assign' properties we use objc_copyStruct() (for the
     next runtime) or objc_setPropertyStruct() (for the GNU runtime).  */
  switch (PROPERTY_ASSIGN_SEMANTICS (property))
    {
    case OBJC_PROPERTY_RETAIN:
    case OBJC_PROPERTY_COPY:
      {
        /* We build "objc_setProperty (self, _cmd, new_value, offset, is_atomic, should_copy);"  */
        tree cmd, ivar, offset, is_atomic, should_copy;
        cmd = TREE_CHAIN (DECL_ARGUMENTS (current_function_decl));

        /* Find the ivar to compute the offset.  */
        ivar = lookup_ivar (klass, PROPERTY_IVAR_NAME (property));
        if (!ivar || is_private (ivar))
          {
            error_at (location,
                      "can not find instance variable associated with property");
            statement = error_mark_node;
            break;
          }
        offset = byte_position (ivar);

        if (PROPERTY_NONATOMIC (property))
          is_atomic = boolean_false_node;
        else
          is_atomic = boolean_true_node;
        
        if (PROPERTY_ASSIGN_SEMANTICS (property) == OBJC_PROPERTY_COPY)
          should_copy = boolean_true_node;
        else
          should_copy = boolean_false_node;

        statement = build_function_call
          (location,
           /* Function prototype.  */
           objc_setProperty_decl,
           /* Parameters.  */
           tree_cons    /* self */
           (NULL_TREE, self_decl,
            tree_cons   /* _cmd */
            (NULL_TREE, cmd,
             tree_cons  /* offset */
             (NULL_TREE, offset,
              tree_cons /* new_value */
              (NULL_TREE, new_value,
               tree_cons /* is_atomic */
               (NULL_TREE, is_atomic, 
                tree_cons /* should_copy */
                (NULL_TREE, should_copy, NULL_TREE)))))));
      }
      break;
    case OBJC_PROPERTY_ASSIGN:    
      if (PROPERTY_NONATOMIC (property))
        {
          /* We build "self->PROPERTY_IVAR_NAME = new_value;"  */
          statement = build_modify_expr
            (location,
             objc_lookup_ivar (NULL_TREE, PROPERTY_IVAR_NAME (property)),
             NULL_TREE, NOP_EXPR, 
             location, new_value, NULL_TREE);
          break;
        }
      else
        {
          /* We build
               objc_setPropertyStruct (&(self->PROPERTY_IVAR_NAME),
                                       &new_value,
                                       sizeof (type of self->PROPERTY_IVAR_NAME),
                                       is_atomic,
                                       false)

             For the NeXT runtime, we need to use objc_copyStruct
             instead of objc_getPropertyStruct.  */
          tree function_decl, size_of, is_atomic;

          /* sizeof (ivar type).  Since the ivar and the property have
             the same type, there is no need to lookup the ivar.  */
          size_of = c_sizeof_or_alignof_type (location, TREE_TYPE (property),
                                              true /* is_sizeof */,
                                              false /* complain */);
          
          if (PROPERTY_NONATOMIC (property))
            is_atomic = boolean_false_node;
          else
            is_atomic = boolean_true_node;
          
          if (flag_next_runtime)
            function_decl = objc_copyStruct_decl;
          else
            function_decl = objc_setPropertyStruct_decl;

          statement = build_function_call 
            (location,
             /* Function prototype.  */
             function_decl,
             /* Parameters.  */
             tree_cons /* &(self->PROPERTY_IVAR_NAME); */
             (NULL_TREE, build_fold_addr_expr_loc (location, 
                                                   objc_lookup_ivar 
                                                   (NULL_TREE, PROPERTY_IVAR_NAME (property))),
              tree_cons /* &new_value */
              (NULL_TREE, build_fold_addr_expr_loc (location, new_value),
               tree_cons /* sizeof (PROPERTY_IVAR) */
               (NULL_TREE, size_of,
                tree_cons /* is_atomic */
                (NULL_TREE, is_atomic,
                 /* TODO: This is currently ignored by the GNU
                    runtime, but what about the next one ? */
                 tree_cons /* has_strong */
                 (NULL_TREE, boolean_true_node, NULL_TREE))))));
        }
      break;
    default:
      gcc_unreachable ();
    }
  gcc_assert (statement);

  add_stmt (statement);  
  add_stmt (c_end_compound_stmt (location, body, true));
  fn = current_function_decl;
#ifdef OBJCPLUS
  finish_function ();
#endif
  objc_finish_method_definition (fn);
}

/* This function is a sub-routine of objc_add_synthesize_declaration.
   It is called for each property to synthesize once we have
   determined that the context is Ok.  */
static void
objc_add_synthesize_declaration_for_property (location_t location, tree interface,
                                              tree property_name, tree ivar_name)
{
  /* Find the @property declaration.  */
  tree property;
  tree x;

  /* Check that synthesize or dynamic has not already been used for
     the same property.  */
  for (property = IMPL_PROPERTY_DECL (objc_implementation_context); property; property = TREE_CHAIN (property))
    if (PROPERTY_NAME (property) == property_name)
      {
        location_t original_location = DECL_SOURCE_LOCATION (property);
        
        if (PROPERTY_DYNAMIC (property))
          error_at (location, "property %qs already specified in %<@dynamic%>", 
                    IDENTIFIER_POINTER (property_name));
        else
          error_at (location, "property %qs already specified in %<@synthesize%>", 
                    IDENTIFIER_POINTER (property_name));
        
        if (original_location != UNKNOWN_LOCATION)
          inform (original_location, "originally specified here");
        return;
      }

  /* Check that the property is declared in the interface.  It could
     also be declared in a superclass or protocol.  */
  property = lookup_property (interface, property_name);

  if (!property)
    {
      error_at (location, "no declaration of property %qs found in the interface", 
                IDENTIFIER_POINTER (property_name));
      return;
    }
  else
    {
      /* We have to copy the property, because we want to chain it to
         the implementation context, and we want to store the source
         location of the @synthesize, not of the original
         @property.  */
      property = copy_node (property);
      DECL_SOURCE_LOCATION (property) = location;
    }

  /* Determine PROPERTY_IVAR_NAME.  */
  if (ivar_name == NULL_TREE)
    ivar_name = property_name;

  /* Check that the instance variable exists.  You can only use an
     instance variable from the same class, not one from the
     superclass (this makes sense as it allows us to check that an
     instance variable is only used in one synthesized property).  */
  {
    tree ivar = is_ivar (CLASS_IVARS (interface), ivar_name);
    tree type_of_ivar;
    if (!ivar)
      {
        error_at (location, "ivar %qs used by %<@synthesize%> declaration must be an existing ivar", 
                  IDENTIFIER_POINTER (property_name));
        return;
      }

    if (DECL_BIT_FIELD_TYPE (ivar))
      type_of_ivar = DECL_BIT_FIELD_TYPE (ivar);
    else
      type_of_ivar = TREE_TYPE (ivar);
    
    /* If the instance variable has a different C type, we throw an error ...  */
    if (!comptypes (TREE_TYPE (property), type_of_ivar)
        /* ... unless the property is readonly, in which case we allow
           the instance variable to be more specialized (this means we
           can generate the getter all right and it works).  */
        && (!PROPERTY_READONLY (property)
            || !objc_compare_types (TREE_TYPE (property),
                                    type_of_ivar, -5, NULL_TREE)))
      {
        location_t original_location = DECL_SOURCE_LOCATION (ivar);
        
        error_at (location, "property %qs is using instance variable %qs of incompatible type",
                  IDENTIFIER_POINTER (property_name),
                  IDENTIFIER_POINTER (ivar_name));
        
        if (original_location != UNKNOWN_LOCATION)
          inform (original_location, "originally specified here");
      }

    /* If the instance variable is a bitfield, the property must be
       'assign', 'nonatomic' because the runtime getter/setter helper
       do not work with bitfield instance variables.  */
    if (DECL_BIT_FIELD_TYPE (ivar))
      {
        /* If there is an error, we return and not generate any
           getter/setter because trying to set up the runtime
           getter/setter helper calls with bitfields is at high risk
           of ICE.  */

        if (PROPERTY_ASSIGN_SEMANTICS (property) != OBJC_PROPERTY_ASSIGN)
          {
            location_t original_location = DECL_SOURCE_LOCATION (ivar);
            
            error_at (location, "'assign' property %qs is using bit-field instance variable %qs",
                      IDENTIFIER_POINTER (property_name),
                      IDENTIFIER_POINTER (ivar_name));
        
            if (original_location != UNKNOWN_LOCATION)
              inform (original_location, "originally specified here");
            return;
          }

        if (!PROPERTY_NONATOMIC (property))
          {
            location_t original_location = DECL_SOURCE_LOCATION (ivar);
            
            error_at (location, "'atomic' property %qs is using bit-field instance variable %qs",
                      IDENTIFIER_POINTER (property_name),
                      IDENTIFIER_POINTER (ivar_name));
            
            if (original_location != UNKNOWN_LOCATION)
              inform (original_location, "originally specified here");
            return;
          }
      }
  }

  /* Check that no other property is using the same instance
     variable.  */
  for (x = IMPL_PROPERTY_DECL (objc_implementation_context); x; x = TREE_CHAIN (x))
    if (PROPERTY_IVAR_NAME (x) == ivar_name)
      {
        location_t original_location = DECL_SOURCE_LOCATION (x);
        
        error_at (location, "property %qs is using the same instance variable as property %qs",
                  IDENTIFIER_POINTER (property_name),
                  IDENTIFIER_POINTER (PROPERTY_NAME (x)));
        
        if (original_location != UNKNOWN_LOCATION)
          inform (original_location, "originally specified here");
        
        /* We keep going on.  This won't cause the compiler to fail;
           the failure would most likely be at runtime.  */
      }

  /* Note that a @synthesize (and only a @synthesize) always sets
     PROPERTY_IVAR_NAME to a non-NULL_TREE.  You can recognize a
     @synthesize by that.  */
  PROPERTY_IVAR_NAME (property) = ivar_name;
  
  /* PROPERTY_SETTER_NAME and PROPERTY_GETTER_NAME are copied from the
     original declaration; they are always set (with the exception of
     PROPERTY_SETTER_NAME not being set if PROPERTY_READONLY == 1).  */

  /* Add the property to the list of properties for current implementation. */
  TREE_CHAIN (property) = IMPL_PROPERTY_DECL (objc_implementation_context);
  IMPL_PROPERTY_DECL (objc_implementation_context) = property;

  /* Note how we don't actually synthesize the getter/setter here; it
     would be very natural, but we may miss the fact that the user has
     implemented his own getter/setter later on in the @implementation
     (in which case we shouldn't generate getter/setter).  We wait
     until we have parsed it all before generating the code.  */
}

/* This function is called by the parser after a @synthesize
   expression is parsed.  'location' is the location of the
   @synthesize expression, and 'property_and_ivar_list' is a chained
   list of the property and ivar names.  */
void
objc_add_synthesize_declaration (location_t location, tree property_and_ivar_list)
{
  tree interface, chain;

  if (flag_objc1_only)
    error_at (input_location, "%<@synthesize%> is not available in Objective-C 1.0");

  if (property_and_ivar_list == error_mark_node)
    return;

  if (!objc_implementation_context)
    {
      /* We can get here only in Objective-C; the Objective-C++ parser
         detects the problem while parsing, outputs the error
         "misplaced '@synthesize' Objective-C++ construct" and skips
         the declaration.  */
      error_at (location, "%<@synthesize%> not in @implementation context");
      return;
    }

  if (TREE_CODE (objc_implementation_context) == CATEGORY_IMPLEMENTATION_TYPE)
    {
      error_at (location, "%<@synthesize%> can not be used in categories");
      return;
    }

  interface = lookup_interface (CLASS_NAME (objc_implementation_context));
  if (!interface)
    {
      /* I can't see how this could happen, but it is good as a safety check.  */
      error_at (location, 
                "%<@synthesize%> requires the @interface of the class to be available");
      return;
    }

  /* Now, iterate over the properties and do each of them.  */
  for (chain = property_and_ivar_list; chain; chain = TREE_CHAIN (chain))
    {
      objc_add_synthesize_declaration_for_property (location, interface, TREE_VALUE (chain), 
                                                    TREE_PURPOSE (chain));
    }
}

/* This function is a sub-routine of objc_add_dynamic_declaration.  It
   is called for each property to mark as dynamic once we have
   determined that the context is Ok.  */
static void
objc_add_dynamic_declaration_for_property (location_t location, tree interface,
                                           tree property_name)
{
  /* Find the @property declaration.  */
  tree property;

  /* Check that synthesize or dynamic has not already been used for
     the same property.  */
  for (property = IMPL_PROPERTY_DECL (objc_implementation_context); property; property = TREE_CHAIN (property))
    if (PROPERTY_NAME (property) == property_name)
      {
        location_t original_location = DECL_SOURCE_LOCATION (property);
        
        if (PROPERTY_DYNAMIC (property))
          error_at (location, "property %qs already specified in %<@dynamic%>", 
                    IDENTIFIER_POINTER (property_name));
        else
          error_at (location, "property %qs already specified in %<@synthesize%>",
                    IDENTIFIER_POINTER (property_name));

        if (original_location != UNKNOWN_LOCATION)
          inform (original_location, "originally specified here");
        return;
      }

  /* Check that the property is declared in the interface.  It could
     also be declared in a superclass or protocol.  */
  property = lookup_property (interface, property_name);

  if (!property)
    {
      error_at (location, "no declaration of property %qs found in the interface",
                IDENTIFIER_POINTER (property_name));
      return;
    }
  else
    {
      /* We have to copy the property, because we want to chain it to
         the implementation context, and we want to store the source
         location of the @synthesize, not of the original
         @property.  */
      property = copy_node (property);
      DECL_SOURCE_LOCATION (property) = location;
    }

  /* Note that a @dynamic (and only a @dynamic) always sets
     PROPERTY_DYNAMIC to 1.  You can recognize a @dynamic by that.
     (actually, as explained above, PROPERTY_DECL generated by
     @property and associated with a @dynamic property are also marked
     as PROPERTY_DYNAMIC).  */
  PROPERTY_DYNAMIC (property) = 1;

  /* Add the property to the list of properties for current implementation. */
  TREE_CHAIN (property) = IMPL_PROPERTY_DECL (objc_implementation_context);
  IMPL_PROPERTY_DECL (objc_implementation_context) = property;
}

/* This function is called by the parser after a @dynamic expression
   is parsed.  'location' is the location of the @dynamic expression,
   and 'property_list' is a chained list of all the property
   names.  */
void
objc_add_dynamic_declaration (location_t location, tree property_list)
{
  tree interface, chain;

  if (flag_objc1_only)
    error_at (input_location, "%<@dynamic%> is not available in Objective-C 1.0");

  if (property_list == error_mark_node)
    return;

  if (!objc_implementation_context)
    {
      /* We can get here only in Objective-C; the Objective-C++ parser
         detects the problem while parsing, outputs the error
         "misplaced '@dynamic' Objective-C++ construct" and skips the
         declaration.  */
      error_at (location, "%<@dynamic%> not in @implementation context");
      return;
    }

  /* @dynamic is allowed in categories.  */
  switch (TREE_CODE (objc_implementation_context))
    {
    case CLASS_IMPLEMENTATION_TYPE:
      interface = lookup_interface (CLASS_NAME (objc_implementation_context));
      break;
    case CATEGORY_IMPLEMENTATION_TYPE:
      interface = lookup_category (implementation_template, 
                                   CLASS_SUPER_NAME (objc_implementation_context));
      break;
    default:
      gcc_unreachable ();
    }

  if (!interface)
    {
      /* I can't see how this could happen, but it is good as a safety check.  */
      error_at (location,
                "%<@dynamic%> requires the @interface of the class to be available");
      return;
    }

  /* Now, iterate over the properties and do each of them.  */
  for (chain = property_list; chain; chain = TREE_CHAIN (chain))
    {
      objc_add_dynamic_declaration_for_property (location, interface, TREE_VALUE (chain));
    }
}

/* Main routine to generate code/data for all the property information for 
   current implementation (class or category). CLASS is the interface where
   ivars are declared.  CLASS_METHODS is where methods are found which
   could be a class or a category depending on whether we are implementing
   property of a class or a category.  */

static void
objc_gen_property_data (tree klass, tree class_methods)
{
  tree x;

  for (x = IMPL_PROPERTY_DECL (objc_implementation_context); x; x = TREE_CHAIN (x))
    {
      /* @dynamic property - nothing to check or synthesize.  */
      if (PROPERTY_DYNAMIC (x))
        continue;
      
      /* @synthesize property - need to synthesize the accessors.  */
      if (PROPERTY_IVAR_NAME (x))
        {
          objc_synthesize_getter (klass, class_methods, x);
          
          if (PROPERTY_READONLY (x) == 0)
            objc_synthesize_setter (klass, class_methods, x);

          continue;
        }

      gcc_unreachable ();
    }
}

/* This is called once we see the "@end" in an interface/implementation.  */

static void
finish_class (tree klass)
{
  switch (TREE_CODE (klass))
    {
    case CLASS_IMPLEMENTATION_TYPE:
      {
        /* All code generation is done in finish_objc.  */
        
        /* Generate what needed for property; setters, getters, etc. */
        objc_gen_property_data (implementation_template, implementation_template);

        if (implementation_template != objc_implementation_context)
          {
            /* Ensure that all method listed in the interface contain bodies.  */
            check_methods (CLASS_CLS_METHODS (implementation_template),
                           objc_implementation_context, '+');
            check_methods (CLASS_NST_METHODS (implementation_template),
                           objc_implementation_context, '-');

            if (CLASS_PROTOCOL_LIST (implementation_template))
              check_protocols (CLASS_PROTOCOL_LIST (implementation_template),
                               "class",
                               CLASS_NAME (objc_implementation_context));
          }
        break;
      }
    case CATEGORY_IMPLEMENTATION_TYPE:
      {
        tree category = lookup_category (implementation_template, CLASS_SUPER_NAME (klass));
        
        if (category)
          {
            /* Generate what needed for property; setters, getters, etc. */
            objc_gen_property_data (implementation_template, category);

            /* Ensure all method listed in the interface contain bodies.  */
            check_methods (CLASS_CLS_METHODS (category),
                           objc_implementation_context, '+');
            check_methods (CLASS_NST_METHODS (category),
                           objc_implementation_context, '-');
            
            if (CLASS_PROTOCOL_LIST (category))
              check_protocols (CLASS_PROTOCOL_LIST (category),
                               "category",
                               CLASS_SUPER_NAME (objc_implementation_context));
          }
        break;
      }
    case CLASS_INTERFACE_TYPE:
    case CATEGORY_INTERFACE_TYPE:
    case PROTOCOL_INTERFACE_TYPE:
      {
        /* Process properties of the class. */
        tree x;
        for (x = CLASS_PROPERTY_DECL (objc_interface_context); x; x = TREE_CHAIN (x))
          {
            /* Now we check that the appropriate getter is declared,
               and if not, we declare one ourselves.  */
            tree getter_decl = lookup_method (CLASS_NST_METHODS (klass),
                                              PROPERTY_GETTER_NAME (x));
            
            if (getter_decl)
              {
                /* TODO: Check that the declaration is consistent with the property.  */
                ;
              }
            else
              {
                /* Generate an instance method declaration for the
                   getter; for example "- (id) name;".  In general it
                   will be of the form
                   -(type)property_getter_name;  */
                tree rettype = build_tree_list (NULL_TREE, TREE_TYPE (x));
                getter_decl = build_method_decl (INSTANCE_METHOD_DECL, 
                                                 rettype, PROPERTY_GETTER_NAME (x), 
                                                 NULL_TREE, false);
                objc_add_method (objc_interface_context, getter_decl, false, false);
                METHOD_PROPERTY_CONTEXT (getter_decl) = x;
              }

            if (PROPERTY_READONLY (x) == 0)
              {
                /* Now we check that the appropriate setter is declared,
                   and if not, we declare on ourselves.  */
                tree setter_decl = lookup_method (CLASS_NST_METHODS (klass), 
                                                  PROPERTY_SETTER_NAME (x));
                
                if (setter_decl)
                  {
                    /* TODO: Check that the declaration is consistent with the property.  */
                    ;
                  }
                else
                  {
                    /* The setter name is something like 'setName:'.
                       We need the substring 'setName' to build the
                       method declaration due to how the declaration
                       works.  TODO: build_method_decl() will then
                       generate back 'setName:' from 'setName'; it
                       would be more efficient to hook into there.  */
                    const char *full_setter_name = IDENTIFIER_POINTER (PROPERTY_SETTER_NAME (x));
                    size_t length = strlen (full_setter_name);
                    char *setter_name = (char *) alloca (length);
                    tree ret_type, selector, arg_type, arg_name;
                    
                    strcpy (setter_name, full_setter_name);
                    setter_name[length - 1] = '\0';
                    ret_type = build_tree_list (NULL_TREE, void_type_node);
                    arg_type = build_tree_list (NULL_TREE, TREE_TYPE (x));
                    arg_name = get_identifier ("_value");
                    selector = objc_build_keyword_decl (get_identifier (setter_name),
                                                        arg_type, arg_name, NULL);
                    setter_decl = build_method_decl (INSTANCE_METHOD_DECL, 
                                                     ret_type, selector,
                                                     build_tree_list (NULL_TREE, NULL_TREE),
                                                     false);
                    objc_add_method (objc_interface_context, setter_decl, false, false);
                    METHOD_PROPERTY_CONTEXT (setter_decl) = x;
                  }            
              }
          }
        break;
      }
    default:
      gcc_unreachable ();
      break;
    }
}

static tree
add_protocol (tree protocol)
{
  /* Put protocol on list in reverse order.  */
  TREE_CHAIN (protocol) = protocol_chain;
  protocol_chain = protocol;
  return protocol_chain;
}

static tree
lookup_protocol (tree ident)
{
  tree chain;

  for (chain = protocol_chain; chain; chain = TREE_CHAIN (chain))
    if (ident == PROTOCOL_NAME (chain))
      return chain;

  return NULL_TREE;
}

/* This function forward declares the protocols named by NAMES.  If
   they are already declared or defined, the function has no effect.  */

void
objc_declare_protocols (tree names)
{
  tree list;

#ifdef OBJCPLUS
  if (current_namespace != global_namespace) {
    error ("Objective-C declarations may only appear in global scope");
  }
#endif /* OBJCPLUS */

  for (list = names; list; list = TREE_CHAIN (list))
    {
      tree name = TREE_VALUE (list);

      if (lookup_protocol (name) == NULL_TREE)
        {
          tree protocol = make_node (PROTOCOL_INTERFACE_TYPE);

          TYPE_LANG_SLOT_1 (protocol)
            = make_tree_vec (PROTOCOL_LANG_SLOT_ELTS);
          PROTOCOL_NAME (protocol) = name;
          PROTOCOL_LIST (protocol) = NULL_TREE;
          add_protocol (protocol);
          PROTOCOL_DEFINED (protocol) = 0;
          PROTOCOL_FORWARD_DECL (protocol) = NULL_TREE;
        }
    }
}

static tree
start_protocol (enum tree_code code, tree name, tree list)
{
  tree protocol;

#ifdef OBJCPLUS
  if (current_namespace != global_namespace) {
    error ("Objective-C declarations may only appear in global scope");
  }
#endif /* OBJCPLUS */

  protocol = lookup_protocol (name);

  if (!protocol)
    {
      protocol = make_node (code);
      TYPE_LANG_SLOT_1 (protocol) = make_tree_vec (PROTOCOL_LANG_SLOT_ELTS);

      PROTOCOL_NAME (protocol) = name;
      PROTOCOL_LIST (protocol) = lookup_and_install_protocols (list);
      add_protocol (protocol);
      PROTOCOL_DEFINED (protocol) = 1;
      PROTOCOL_FORWARD_DECL (protocol) = NULL_TREE;

      check_protocol_recursively (protocol, list);
    }
  else if (! PROTOCOL_DEFINED (protocol))
    {
      PROTOCOL_DEFINED (protocol) = 1;
      PROTOCOL_LIST (protocol) = lookup_and_install_protocols (list);

      check_protocol_recursively (protocol, list);
    }
  else
    {
      warning (0, "duplicate declaration for protocol %qE",
               name);
    }
  return protocol;
}

\f
/* "Encode" a data type into a string, which grows in util_obstack.

   The format is described in gcc/doc/objc.texi, section 'Type
   encoding'.

   Most of the encode_xxx functions have a 'type' argument, which is
   the type to encode, and an integer 'curtype' argument, which is the
   index in the encoding string of the beginning of the encoding of
   the current type, and allows you to find what characters have
   already been written for the current type (they are the ones in the
   current encoding string starting from 'curtype').

   For example, if we are encoding a method which returns 'int' and
   takes a 'char **' argument, then when we get to the point of
   encoding the 'char **' argument, the encoded string already
   contains 'i12@0:4' (assuming a pointer size of 4 bytes).  So,
   'curtype' will be set to 7 when starting to encode 'char **'.
   During the whole of the encoding of 'char **', 'curtype' will be
   fixed at 7, so the routine encoding the second pointer can find out
   that it's actually encoding a pointer to a pointer by looking
   backwards at what has already been encoded for the current type,
   and seeing there is a "^" (meaning a pointer) in there.
*/


/* Encode type qualifiers encodes one of the "PQ" Objective-C
   keywords, ie 'in', 'out', 'inout', 'bycopy', 'byref', 'oneway'.
   'const', instead, is encoded directly as part of the type.
 */

static void
encode_type_qualifiers (tree declspecs)
{
  tree spec;

  for (spec = declspecs; spec; spec = TREE_CHAIN (spec))
    {
      /* FIXME: Shouldn't we use token->keyword here ? */
      if (ridpointers[(int) RID_IN] == TREE_VALUE (spec))
        obstack_1grow (&util_obstack, 'n');
      else if (ridpointers[(int) RID_INOUT] == TREE_VALUE (spec))
        obstack_1grow (&util_obstack, 'N');
      else if (ridpointers[(int) RID_OUT] == TREE_VALUE (spec))
        obstack_1grow (&util_obstack, 'o');
      else if (ridpointers[(int) RID_BYCOPY] == TREE_VALUE (spec))
        obstack_1grow (&util_obstack, 'O');
      else if (ridpointers[(int) RID_BYREF] == TREE_VALUE (spec))
        obstack_1grow (&util_obstack, 'R');
      else if (ridpointers[(int) RID_ONEWAY] == TREE_VALUE (spec))
        obstack_1grow (&util_obstack, 'V');
      else
        gcc_unreachable ();
    }
}

/* Determine if a pointee is marked read-only.  Only used by the NeXT
   runtime to be compatible with gcc-3.3.  */

static bool
pointee_is_readonly (tree pointee)
{
  while (POINTER_TYPE_P (pointee))
    pointee = TREE_TYPE (pointee);

  return TYPE_READONLY (pointee);
}

/* Encode a pointer type.  */

static void
encode_pointer (tree type, int curtype, int format)
{
  tree pointer_to = TREE_TYPE (type);

  if (flag_next_runtime)
    {
      /* This code is used to be compatible with gcc-3.3.  */
      /* For historical/compatibility reasons, the read-only qualifier
         of the pointee gets emitted _before_ the '^'.  The read-only
         qualifier of the pointer itself gets ignored, _unless_ we are
         looking at a typedef!  Also, do not emit the 'r' for anything
         but the outermost type!  */
      if (!generating_instance_variables
          && (obstack_object_size (&util_obstack) - curtype <= 1)
          && (TYPE_NAME (type) && TREE_CODE (TYPE_NAME (type)) == TYPE_DECL
              ? TYPE_READONLY (type)
              : pointee_is_readonly (pointer_to)))
        obstack_1grow (&util_obstack, 'r');
    }

  if (TREE_CODE (pointer_to) == RECORD_TYPE)
    {
      if (OBJC_TYPE_NAME (pointer_to)
          && TREE_CODE (OBJC_TYPE_NAME (pointer_to)) == IDENTIFIER_NODE)
        {
          const char *name = IDENTIFIER_POINTER (OBJC_TYPE_NAME (pointer_to));

          if (strcmp (name, TAG_OBJECT) == 0) /* '@' */
            {
              obstack_1grow (&util_obstack, '@');
              return;
            }
          else if (TYPE_HAS_OBJC_INFO (pointer_to)
                   && TYPE_OBJC_INTERFACE (pointer_to))
            {
              if (generating_instance_variables)
                {
                  obstack_1grow (&util_obstack, '@');
                  obstack_1grow (&util_obstack, '"');
                  obstack_grow (&util_obstack, name, strlen (name));
                  obstack_1grow (&util_obstack, '"');
                  return;
                }
              else
                {
                  obstack_1grow (&util_obstack, '@');
                  return;
                }
            }
          else if (strcmp (name, TAG_CLASS) == 0) /* '#' */
            {
              obstack_1grow (&util_obstack, '#');
              return;
            }
          else if (strcmp (name, TAG_SELECTOR) == 0) /* ':' */
            {
              obstack_1grow (&util_obstack, ':');
              return;
            }
        }
    }
  else if (TREE_CODE (pointer_to) == INTEGER_TYPE
           && TYPE_MODE (pointer_to) == QImode)
    {
      tree pname = TREE_CODE (OBJC_TYPE_NAME (pointer_to)) == IDENTIFIER_NODE
                  ? OBJC_TYPE_NAME (pointer_to)
                  : DECL_NAME (OBJC_TYPE_NAME (pointer_to));

      /* (BOOL *) are an exception and are encoded as ^c, while all
         other pointers to char are encoded as *.   */
      if (strcmp (IDENTIFIER_POINTER (pname), "BOOL"))
        {
          if (!flag_next_runtime)
            {
              /* The NeXT runtime adds the 'r' before getting here.  */

              /* It appears that "r*" means "const char *" rather than
                 "char *const".  "char *const" is encoded as "*",
                 which is identical to "char *", so the "const" is
                 unfortunately lost.  */                 
              if (TYPE_READONLY (pointer_to))
                obstack_1grow (&util_obstack, 'r');
            }

          obstack_1grow (&util_obstack, '*');
          return;
        }
    }

  /* We have a normal pointer type that does not get special treatment.  */
  obstack_1grow (&util_obstack, '^');
  encode_type (pointer_to, curtype, format);
}

static void
encode_array (tree type, int curtype, int format)
{
  tree an_int_cst = TYPE_SIZE (type);
  tree array_of = TREE_TYPE (type);
  char buffer[40];
  
  if (an_int_cst == NULL)
    {
      /* We are trying to encode an incomplete array.  An incomplete
         array is forbidden as part of an instance variable.  */
      if (generating_instance_variables)
        {
          /* TODO: Detect this error earlier.  */
          error ("instance variable has unknown size");
          return;
        }

      /* So the only case in which an incomplete array could occur is
         if we are encoding the arguments or return value of a method.
         In that case, an incomplete array argument or return value
         (eg, -(void)display: (char[])string) is treated like a
         pointer because that is how the compiler does the function
         call.  A special, more complicated case, is when the
         incomplete array is the last member of a struct (eg, if we
         are encoding "struct { unsigned long int a;double b[];}"),
         which is again part of a method argument/return value.  In
         that case, we really need to communicate to the runtime that
         there is an incomplete array (not a pointer!) there.  So, we
         detect that special case and encode it as a zero-length
         array.

         Try to detect that we are part of a struct.  We do this by
         searching for '=' in the type encoding for the current type.
         NB: This hack assumes that you can't use '=' as part of a C
         identifier.
      */
      {
        char *enc = obstack_base (&util_obstack) + curtype;
        if (memchr (enc, '=', 
                    obstack_object_size (&util_obstack) - curtype) == NULL)
          {
            /* We are not inside a struct.  Encode the array as a
               pointer.  */
            encode_pointer (type, curtype, format);
            return;
          }
      }

      /* Else, we are in a struct, and we encode it as a zero-length
         array.  */
      sprintf (buffer, "[" HOST_WIDE_INT_PRINT_DEC, (HOST_WIDE_INT)0);
    }
  else if (TREE_INT_CST_LOW (TYPE_SIZE (array_of)) == 0)
   sprintf (buffer, "[" HOST_WIDE_INT_PRINT_DEC, (HOST_WIDE_INT)0);
  else
    sprintf (buffer, "[" HOST_WIDE_INT_PRINT_DEC,
             TREE_INT_CST_LOW (an_int_cst)
              / TREE_INT_CST_LOW (TYPE_SIZE (array_of)));

  obstack_grow (&util_obstack, buffer, strlen (buffer));
  encode_type (array_of, curtype, format);
  obstack_1grow (&util_obstack, ']');
  return;
}

/* Encode a vector.  The vector type is a GCC extension to C.  */
static void
encode_vector (tree type, int curtype, int format)
{
  tree vector_of = TREE_TYPE (type);
  char buffer[40];

  /* Vectors are like simple fixed-size arrays.  */

  /* Output ![xx,yy,<code>] where xx is the vector_size, yy is the
     alignment of the vector, and <code> is the base type.  Eg, int
     __attribute__ ((vector_size (16))) gets encoded as ![16,32,i]
     assuming that the alignment is 32 bytes.  We include size and
     alignment in bytes so that the runtime does not have to have any
     knowledge of the actual types.
  */
  sprintf (buffer, "![" HOST_WIDE_INT_PRINT_DEC ",%d",
           /* We want to compute the equivalent of sizeof (<vector>).
              Code inspired by c_sizeof_or_alignof_type.  */
           ((TREE_INT_CST_LOW (TYPE_SIZE_UNIT (type)) 
             / (TYPE_PRECISION (char_type_node) / BITS_PER_UNIT))),
           /* We want to compute the equivalent of __alignof__
              (<vector>).  Code inspired by
              c_sizeof_or_alignof_type.  */
           TYPE_ALIGN_UNIT (type));
  obstack_grow (&util_obstack, buffer, strlen (buffer));
  encode_type (vector_of, curtype, format);
  obstack_1grow (&util_obstack, ']');
  return;
}
\f
static void
encode_aggregate_fields (tree type, bool pointed_to, int curtype, int format)
{
  tree field = TYPE_FIELDS (type);

  for (; field; field = DECL_CHAIN (field))
    {
#ifdef OBJCPLUS
      /* C++ static members, and things that are not field at all,
         should not appear in the encoding.  */
      if (TREE_CODE (field) != FIELD_DECL || TREE_STATIC (field))
        continue;
#endif

      /* Recursively encode fields of embedded base classes.  */
      if (DECL_ARTIFICIAL (field) && !DECL_NAME (field)
          && TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE)
        {
          encode_aggregate_fields (TREE_TYPE (field),
                                   pointed_to, curtype, format);
          continue;
        }

      if (generating_instance_variables && !pointed_to)
        {
          tree fname = DECL_NAME (field);

          obstack_1grow (&util_obstack, '"');

          if (fname && TREE_CODE (fname) == IDENTIFIER_NODE)
            obstack_grow (&util_obstack,
                          IDENTIFIER_POINTER (fname),
                          strlen (IDENTIFIER_POINTER (fname)));

          obstack_1grow (&util_obstack, '"');
        }

      encode_field_decl (field, curtype, format);
    }
}

static void
encode_aggregate_within (tree type, int curtype, int format, int left,
                         int right)
{
  tree name;
  /* NB: aggregates that are pointed to have slightly different encoding
     rules in that you never encode the names of instance variables.  */
  int ob_size = obstack_object_size (&util_obstack);
  bool inline_contents = false;
  bool pointed_to = false;

  if (flag_next_runtime)
    {
      if (ob_size > 0  &&  *(obstack_next_free (&util_obstack) - 1) == '^')
        pointed_to = true;

      if ((format == OBJC_ENCODE_INLINE_DEFS || generating_instance_variables)
          && (!pointed_to || ob_size - curtype == 1
              || (ob_size - curtype == 2
                  && *(obstack_next_free (&util_obstack) - 2) == 'r')))
        inline_contents = true;
    }
  else
    {
      /* c0 and c1 are the last two characters in the encoding of the
         current type; if the last two characters were '^' or '^r',
         then we are encoding an aggregate that is "pointed to".  The
         comment above applies: in that case we should avoid encoding
         the names of instance variables.
      */
      char c1 = ob_size > 1 ? *(obstack_next_free (&util_obstack) - 2) : 0;
      char c0 = ob_size > 0 ? *(obstack_next_free (&util_obstack) - 1) : 0;
      
      if (c0 == '^' || (c1 == '^' && c0 == 'r'))
        pointed_to = true;
      
      if (format == OBJC_ENCODE_INLINE_DEFS || generating_instance_variables)
        {
          if (!pointed_to)
            inline_contents = true;
          else
            {
              /* Note that the check (ob_size - curtype < 2) prevents
                 infinite recursion when encoding a structure which is
                 a linked list (eg, struct node { struct node *next;
                 }).  Each time we follow a pointer, we add one
                 character to ob_size, and curtype is fixed, so after
                 at most two pointers we stop inlining contents and
                 break the loop.

                 The other case where we don't inline is "^r", which
                 is a pointer to a constant struct.
              */
              if ((ob_size - curtype <= 2) && !(c0 == 'r'))
                inline_contents = true;
            }
        }
    }

  /* Traverse struct aliases; it is important to get the
     original struct and its tag name (if any).  */
  type = TYPE_MAIN_VARIANT (type);
  name = OBJC_TYPE_NAME (type);
  /* Open parenth/bracket.  */
  obstack_1grow (&util_obstack, left);

  /* Encode the struct/union tag name, or '?' if a tag was
     not provided.  Typedef aliases do not qualify.  */
#ifdef OBJCPLUS
  /* For compatibility with the NeXT runtime, ObjC++ encodes template
     args as a composite struct tag name. */
  if (name && TREE_CODE (name) == IDENTIFIER_NODE
      /* Did this struct have a tag?  */
      && !TYPE_WAS_ANONYMOUS (type))
    obstack_grow (&util_obstack,
                  decl_as_string (type, TFF_DECL_SPECIFIERS | TFF_UNQUALIFIED_NAME),
                  strlen (decl_as_string (type, TFF_DECL_SPECIFIERS | TFF_UNQUALIFIED_NAME)));
#else
  if (name && TREE_CODE (name) == IDENTIFIER_NODE)
    obstack_grow (&util_obstack,
                  IDENTIFIER_POINTER (name),
                  strlen (IDENTIFIER_POINTER (name)));
#endif
  else
    obstack_1grow (&util_obstack, '?');

  /* Encode the types (and possibly names) of the inner fields,
     if required.  */
  if (inline_contents)
    {
      obstack_1grow (&util_obstack, '=');
      encode_aggregate_fields (type, pointed_to, curtype, format);
    }
  /* Close parenth/bracket.  */
  obstack_1grow (&util_obstack, right);
}

/* Encode a bitfield NeXT-style (i.e., without a bit offset or the underlying
   field type.  */

static void
encode_next_bitfield (int width)
{
  char buffer[40];
  sprintf (buffer, "b%d", width);
  obstack_grow (&util_obstack, buffer, strlen (buffer));
}
\f

/* Encodes 'type', ignoring type qualifiers (which you should encode
   beforehand if needed) with the exception of 'const', which is
   encoded by encode_type.  See above for the explanation of
   'curtype'.  'format' can be OBJC_ENCODE_INLINE_DEFS or
   OBJC_ENCODE_DONT_INLINE_DEFS.
*/
static void
encode_type (tree type, int curtype, int format)
{
  enum tree_code code = TREE_CODE (type);

  /* Ignore type qualifiers other than 'const' when encoding a
     type.  */

  if (type == error_mark_node)
    return;

  if (!flag_next_runtime)
    {
      if (TYPE_READONLY (type))
        obstack_1grow (&util_obstack, 'r');
    }

  switch (code)
    {
    case ENUMERAL_TYPE:
      if (flag_next_runtime)
        {
          /* Kludge for backwards-compatibility with gcc-3.3: enums
             are always encoded as 'i' no matter what type they
             actually are (!).  */
          obstack_1grow (&util_obstack, 'i');
          break;
        }
      /* Else, they are encoded exactly like the integer type that is
         used by the compiler to store them.  */
    case INTEGER_TYPE:
      {
        char c;
        switch (GET_MODE_BITSIZE (TYPE_MODE (type)))
          {
          case 8:  c = TYPE_UNSIGNED (type) ? 'C' : 'c'; break;
          case 16: c = TYPE_UNSIGNED (type) ? 'S' : 's'; break;
          case 32:
            {
              tree int_type = type;
              if (flag_next_runtime)
                {
                  /* Another legacy kludge for compatiblity with
                     gcc-3.3: 32-bit longs are encoded as 'l' or 'L',
                     but not always.  For typedefs, we need to use 'i'
                     or 'I' instead if encoding a struct field, or a
                     pointer!  */
                  int_type =  ((!generating_instance_variables
                                && (obstack_object_size (&util_obstack)
                                    == (unsigned) curtype))
                               ? TYPE_MAIN_VARIANT (type)
                               : type);
                }
              if (int_type == long_unsigned_type_node
                  || int_type == long_integer_type_node)
                c = TYPE_UNSIGNED (type) ? 'L' : 'l';
              else
                c = TYPE_UNSIGNED (type) ? 'I' : 'i';
            }
            break;
          case 64:  c = TYPE_UNSIGNED (type) ? 'Q' : 'q'; break;
          case 128: c = TYPE_UNSIGNED (type) ? 'T' : 't'; break;
          default: gcc_unreachable ();
          }
        obstack_1grow (&util_obstack, c);
        break;
      }
    case REAL_TYPE:
      {
        char c;
        /* Floating point types.  */
        switch (GET_MODE_BITSIZE (TYPE_MODE (type)))
          {
          case 32:  c = 'f'; break;
          case 64:  c = 'd'; break;
          case 96:
          case 128: c = 'D'; break;
          default: gcc_unreachable ();
          }
        obstack_1grow (&util_obstack, c);
        break;
      }
    case VOID_TYPE:
      obstack_1grow (&util_obstack, 'v');
      break;

    case BOOLEAN_TYPE:
      obstack_1grow (&util_obstack, 'B');
      break;

    case ARRAY_TYPE:
      encode_array (type, curtype, format);
      break;

    case POINTER_TYPE:
#ifdef OBJCPLUS
    case REFERENCE_TYPE:
#endif
      encode_pointer (type, curtype, format);
      break;

    case RECORD_TYPE:
      encode_aggregate_within (type, curtype, format, '{', '}');
      break;

    case UNION_TYPE:
      encode_aggregate_within (type, curtype, format, '(', ')');
      break;

    case FUNCTION_TYPE: /* '?' means an unknown type.  */
      obstack_1grow (&util_obstack, '?');
      break;

    case COMPLEX_TYPE:
      /* A complex is encoded as 'j' followed by the inner type (eg,
         "_Complex int" is encoded as 'ji').  */
      obstack_1grow (&util_obstack, 'j');
      encode_type (TREE_TYPE (type), curtype, format);
      break;

    case VECTOR_TYPE:
      encode_vector (type, curtype, format);
      break;

    default:
      warning (0, "unknown type %s found during Objective-C encoding",
               gen_type_name (type));
      obstack_1grow (&util_obstack, '?');
      break;
    }
  
  if (flag_next_runtime)
    {
      /* Super-kludge.  Some ObjC qualifier and type combinations need
         to be rearranged for compatibility with gcc-3.3.  */
      if (code == POINTER_TYPE && obstack_object_size (&util_obstack) >= 3)
        {
          char *enc = obstack_base (&util_obstack) + curtype;
          
          /* Rewrite "in const" from "nr" to "rn".  */
          if (curtype >= 1 && !strncmp (enc - 1, "nr", 2))
            strncpy (enc - 1, "rn", 2);
        }
    }
}

static void
encode_gnu_bitfield (int position, tree type, int size)
{
  enum tree_code code = TREE_CODE (type);
  char buffer[40];
  char charType = '?';

  /* This code is only executed for the GNU runtime, so we can ignore
     the NeXT runtime kludge of always encoding enums as 'i' no matter
     what integers they actually are.  */
  if (code == INTEGER_TYPE  ||  code == ENUMERAL_TYPE)
    {
      if (integer_zerop (TYPE_MIN_VALUE (type)))
        /* Unsigned integer types.  */
        {
          switch (TYPE_MODE (type))
            {
            case QImode:
              charType = 'C'; break;
            case HImode:
              charType = 'S'; break;
            case SImode:
              {
                if (type == long_unsigned_type_node)
                  charType = 'L';
                else
                  charType = 'I';
                break;
              }
            case DImode:
              charType = 'Q'; break;
            default:
              gcc_unreachable ();
            }
        }
      else
        /* Signed integer types.  */
        {
          switch (TYPE_MODE (type))
            {
            case QImode:
              charType = 'c'; break;
            case HImode:
              charType = 's'; break;
            case SImode:
              {
                if (type == long_integer_type_node)
                  charType = 'l';
                else
                  charType = 'i';
                break;
              }
            case DImode:
              charType = 'q'; break;
            default:
              gcc_unreachable ();
            }
        }
    }
  else
    {
      /* Do not do any encoding, produce an error and keep going.  */
      error ("trying to encode non-integer type as a bitfield");
      return;
    }

  sprintf (buffer, "b%d%c%d", position, charType, size);
  obstack_grow (&util_obstack, buffer, strlen (buffer));
}

static void
encode_field_decl (tree field_decl, int curtype, int format)
{
#ifdef OBJCPLUS
  /* C++ static members, and things that are not fields at all,
     should not appear in the encoding.  */
  if (TREE_CODE (field_decl) != FIELD_DECL || TREE_STATIC (field_decl))
    return;
#endif

  /* Generate the bitfield typing information, if needed.  Note the difference
     between GNU and NeXT runtimes.  */
  if (DECL_BIT_FIELD_TYPE (field_decl))
    {
      int size = tree_low_cst (DECL_SIZE (field_decl), 1);

      if (flag_next_runtime)
        encode_next_bitfield (size);
      else
        encode_gnu_bitfield (int_bit_position (field_decl),
                             DECL_BIT_FIELD_TYPE (field_decl), size);
    }
  else
    encode_type (TREE_TYPE (field_decl), curtype, format);
}

/* Decay array and function parameters into pointers.  */

static tree
objc_decay_parm_type (tree type)
{
  if (TREE_CODE (type) == ARRAY_TYPE || TREE_CODE (type) == FUNCTION_TYPE)
    type = build_pointer_type (TREE_CODE (type) == ARRAY_TYPE
                               ? TREE_TYPE (type)
                               : type);

  return type;
}

static GTY(()) tree objc_parmlist = NULL_TREE;

/* Append PARM to a list of formal parameters of a method, making a necessary
   array-to-pointer adjustment along the way.  */

static void
objc_push_parm (tree parm)
{
  tree type;

  if (TREE_TYPE (parm) == error_mark_node)
    {
      objc_parmlist = chainon (objc_parmlist, parm);
      return;
    }

  /* Decay arrays and functions into pointers.  */
  type = objc_decay_parm_type (TREE_TYPE (parm));

  /* If the parameter type has been decayed, a new PARM_DECL needs to be
     built as well.  */
  if (type != TREE_TYPE (parm))
    parm = build_decl (input_location, PARM_DECL, DECL_NAME (parm), type);

  DECL_ARG_TYPE (parm)
    = lang_hooks.types.type_promotes_to (TREE_TYPE (parm));

  /* Record constancy and volatility.  */
  c_apply_type_quals_to_decl
  ((TYPE_READONLY (TREE_TYPE (parm)) ? TYPE_QUAL_CONST : 0)
   | (TYPE_RESTRICT (TREE_TYPE (parm)) ? TYPE_QUAL_RESTRICT : 0)
   | (TYPE_VOLATILE (TREE_TYPE (parm)) ? TYPE_QUAL_VOLATILE : 0), parm);

  objc_parmlist = chainon (objc_parmlist, parm);
}

/* Retrieve the formal parameter list constructed via preceding calls to
   objc_push_parm().  */

#ifdef OBJCPLUS
static tree
objc_get_parm_info (int have_ellipsis ATTRIBUTE_UNUSED)
#else
static struct c_arg_info *
objc_get_parm_info (int have_ellipsis)
#endif
{
#ifdef OBJCPLUS
  tree parm_info = objc_parmlist;
  objc_parmlist = NULL_TREE;

  return parm_info;
#else
  tree parm_info = objc_parmlist;
  struct c_arg_info *arg_info;
  /* The C front-end requires an elaborate song and dance at
     this point.  */
  push_scope ();
  declare_parm_level ();
  while (parm_info)
    {
      tree next = DECL_CHAIN (parm_info);

      DECL_CHAIN (parm_info) = NULL_TREE;
      parm_info = pushdecl (parm_info);
      finish_decl (parm_info, input_location, NULL_TREE, NULL_TREE, NULL_TREE);
      parm_info = next;
    }
  arg_info = get_parm_info (have_ellipsis);
  pop_scope ();
  objc_parmlist = NULL_TREE;
  return arg_info;
#endif
}

/* Synthesize the formal parameters 'id self' and 'SEL _cmd' needed for ObjC
   method definitions.  In the case of instance methods, we can be more
   specific as to the type of 'self'.  */

static void
synth_self_and_ucmd_args (void)
{
  tree self_type;

  if (objc_method_context
      && TREE_CODE (objc_method_context) == INSTANCE_METHOD_DECL)
    self_type = objc_instance_type;
  else
    /* Really a `struct objc_class *'. However, we allow people to
       assign to self, which changes its type midstream.  */
    self_type = objc_object_type;

  /* id self; */
  objc_push_parm (build_decl (input_location,
                              PARM_DECL, self_id, self_type));

  /* SEL _cmd; */
  objc_push_parm (build_decl (input_location,
                              PARM_DECL, ucmd_id, objc_selector_type));
}

/* Transform an Objective-C method definition into a static C function
   definition, synthesizing the first two arguments, "self" and "_cmd",
   in the process.  */

static void
start_method_def (tree method)
{
  tree parmlist;
#ifdef OBJCPLUS
  tree parm_info;
#else
  struct c_arg_info *parm_info;
#endif
  int have_ellipsis = 0;

  /* If we are defining a "dealloc" method in a non-root class, we
     will need to check if a [super dealloc] is missing, and warn if
     it is.  */
  if(CLASS_SUPER_NAME (objc_implementation_context)
     && !strcmp ("dealloc", IDENTIFIER_POINTER (METHOD_SEL_NAME (method))))
    should_call_super_dealloc = 1;
  else
    should_call_super_dealloc = 0;

  /* Required to implement _msgSuper.  */
  objc_method_context = method;
  UOBJC_SUPER_decl = NULL_TREE;

  /* Generate prototype declarations for arguments..."new-style".  */
  synth_self_and_ucmd_args ();

  /* Generate argument declarations if a keyword_decl.  */
  parmlist = METHOD_SEL_ARGS (method);
  while (parmlist)
    {
      /* parmlist is a KEYWORD_DECL.  */
      tree type = TREE_VALUE (TREE_TYPE (parmlist));
      tree parm;

      parm = build_decl (input_location,
                         PARM_DECL, KEYWORD_ARG_NAME (parmlist), type);
      decl_attributes (&parm, DECL_ATTRIBUTES (parmlist), 0);
      objc_push_parm (parm);
      parmlist = DECL_CHAIN (parmlist);
    }

  if (METHOD_ADD_ARGS (method))
    {
      tree akey;

      for (akey = TREE_CHAIN (METHOD_ADD_ARGS (method));
           akey; akey = TREE_CHAIN (akey))
        {
          objc_push_parm (TREE_VALUE (akey));
        }

      if (METHOD_ADD_ARGS_ELLIPSIS_P (method))
        have_ellipsis = 1;
    }

  parm_info = objc_get_parm_info (have_ellipsis);

  really_start_method (objc_method_context, parm_info);
}

/* Return 1 if TYPE1 is equivalent to TYPE2
   for purposes of method overloading.  */

static int
objc_types_are_equivalent (tree type1, tree type2)
{
  if (type1 == type2)
    return 1;

  /* Strip away indirections.  */
  while ((TREE_CODE (type1) == ARRAY_TYPE || TREE_CODE (type1) == POINTER_TYPE)
         && (TREE_CODE (type1) == TREE_CODE (type2)))
    type1 = TREE_TYPE (type1), type2 = TREE_TYPE (type2);
  if (TYPE_MAIN_VARIANT (type1) != TYPE_MAIN_VARIANT (type2))
    return 0;

  type1 = (TYPE_HAS_OBJC_INFO (type1)
           ? TYPE_OBJC_PROTOCOL_LIST (type1)
           : NULL_TREE);
  type2 = (TYPE_HAS_OBJC_INFO (type2)
           ? TYPE_OBJC_PROTOCOL_LIST (type2)
           : NULL_TREE);

  if (list_length (type1) == list_length (type2))
    {
      for (; type2; type2 = TREE_CHAIN (type2))
        if (!lookup_protocol_in_reflist (type1, TREE_VALUE (type2)))
          return 0;
      return 1;
    }
  return 0;
}

/* Return 1 if TYPE1 has the same size and alignment as TYPE2.  */

static int
objc_types_share_size_and_alignment (tree type1, tree type2)
{
  return (simple_cst_equal (TYPE_SIZE (type1), TYPE_SIZE (type2))
          && TYPE_ALIGN (type1) == TYPE_ALIGN (type2));
}

/* Return 1 if PROTO1 is equivalent to PROTO2
   for purposes of method overloading.  Ordinarily, the type signatures
   should match up exactly, unless STRICT is zero, in which case we
   shall allow differences in which the size and alignment of a type
   is the same.  */

static int
comp_proto_with_proto (tree proto1, tree proto2, int strict)
{
  /* The following test is needed in case there are hashing
     collisions.  */
  if (METHOD_SEL_NAME (proto1) != METHOD_SEL_NAME (proto2))
    return 0;

  return match_proto_with_proto (proto1, proto2, strict);
}

static int
match_proto_with_proto (tree proto1, tree proto2, int strict)
{
  tree type1, type2;

  /* Compare return types.  */
  type1 = TREE_VALUE (TREE_TYPE (proto1));
  type2 = TREE_VALUE (TREE_TYPE (proto2));

  if (!objc_types_are_equivalent (type1, type2)
      && (strict || !objc_types_share_size_and_alignment (type1, type2)))
    return 0;

  /* Compare argument types.  */
  for (type1 = get_arg_type_list (proto1, METHOD_REF, 0),
       type2 = get_arg_type_list (proto2, METHOD_REF, 0);
       type1 && type2;
       type1 = TREE_CHAIN (type1), type2 = TREE_CHAIN (type2))
    {
      if (!objc_types_are_equivalent (TREE_VALUE (type1), TREE_VALUE (type2))
          && (strict
              || !objc_types_share_size_and_alignment (TREE_VALUE (type1),
                                                       TREE_VALUE (type2))))
        return 0;
    }

  return (!type1 && !type2);
}

/* Fold an OBJ_TYPE_REF expression for ObjC method dispatches, where
   this occurs.  ObjC method dispatches are _not_ like C++ virtual
   member function dispatches, and we account for the difference here.  */
tree
#ifdef OBJCPLUS
objc_fold_obj_type_ref (tree ref, tree known_type)
#else
objc_fold_obj_type_ref (tree ref ATTRIBUTE_UNUSED,
                        tree known_type ATTRIBUTE_UNUSED)
#endif
{
#ifdef OBJCPLUS
  tree v = BINFO_VIRTUALS (TYPE_BINFO (known_type));

  /* If the receiver does not have virtual member functions, there
     is nothing we can (or need to) do here.  */
  if (!v)
    return NULL_TREE;

  /* Let C++ handle C++ virtual functions.  */
  return cp_fold_obj_type_ref (ref, known_type);
#else
  /* For plain ObjC, we currently do not need to do anything.  */
  return NULL_TREE;
#endif
}

static void
objc_start_function (tree name, tree type, tree attrs,
#ifdef OBJCPLUS
                     tree params
#else
                     struct c_arg_info *params
#endif
                     )
{
  tree fndecl = build_decl (input_location,
                            FUNCTION_DECL, name, type);

#ifdef OBJCPLUS
  DECL_ARGUMENTS (fndecl) = params;
  DECL_INITIAL (fndecl) = error_mark_node;
  DECL_EXTERNAL (fndecl) = 0;
  TREE_STATIC (fndecl) = 1;
  retrofit_lang_decl (fndecl);
  cplus_decl_attributes (&fndecl, attrs, 0);
  start_preparsed_function (fndecl, attrs, /*flags=*/SF_DEFAULT);
#else
  current_function_returns_value = 0;  /* Assume, until we see it does.  */
  current_function_returns_null = 0;
  decl_attributes (&fndecl, attrs, 0);
  announce_function (fndecl);
  DECL_INITIAL (fndecl) = error_mark_node;
  DECL_EXTERNAL (fndecl) = 0;
  TREE_STATIC (fndecl) = 1;
  current_function_decl = pushdecl (fndecl);
  push_scope ();
  declare_parm_level ();
  DECL_RESULT (current_function_decl)
    = build_decl (input_location,
                  RESULT_DECL, NULL_TREE,
                  TREE_TYPE (TREE_TYPE (current_function_decl)));
  DECL_ARTIFICIAL (DECL_RESULT (current_function_decl)) = 1;
  DECL_IGNORED_P (DECL_RESULT (current_function_decl)) = 1;
  start_fname_decls ();
  store_parm_decls_from (params);
#endif

  TREE_USED (current_function_decl) = 1;
}

/* - Generate an identifier for the function. the format is "_n_cls",
     where 1 <= n <= nMethods, and cls is the name the implementation we
     are processing.
   - Install the return type from the method declaration.
   - If we have a prototype, check for type consistency.  */

static void
really_start_method (tree method,
#ifdef OBJCPLUS
                     tree parmlist
#else
                     struct c_arg_info *parmlist
#endif
                     )
{
  tree ret_type, meth_type;
  tree method_id;
  const char *sel_name, *class_name, *cat_name;
  char *buf;

  /* Synth the storage class & assemble the return type.  */
  ret_type = TREE_VALUE (TREE_TYPE (method));

  sel_name = IDENTIFIER_POINTER (METHOD_SEL_NAME (method));
  class_name = IDENTIFIER_POINTER (CLASS_NAME (objc_implementation_context));
  cat_name = ((TREE_CODE (objc_implementation_context)
               == CLASS_IMPLEMENTATION_TYPE)
              ? NULL
              : IDENTIFIER_POINTER (CLASS_SUPER_NAME (objc_implementation_context)));
  method_slot++;

  /* Make sure this is big enough for any plausible method label.  */
  buf = (char *) alloca (50 + strlen (sel_name) + strlen (class_name)
                         + (cat_name ? strlen (cat_name) : 0));

  OBJC_GEN_METHOD_LABEL (buf, TREE_CODE (method) == INSTANCE_METHOD_DECL,
                         class_name, cat_name, sel_name, method_slot);

  method_id = get_identifier (buf);

#ifdef OBJCPLUS
  /* Objective-C methods cannot be overloaded, so we don't need
     the type encoding appended.  It looks bad anyway... */
  push_lang_context (lang_name_c);
#endif

  meth_type
    = build_function_type (ret_type,
                           get_arg_type_list (method, METHOD_DEF, 0));
  objc_start_function (method_id, meth_type, NULL_TREE, parmlist);

  /* Set self_decl from the first argument.  */
  self_decl = DECL_ARGUMENTS (current_function_decl);

  /* Suppress unused warnings.  */
  TREE_USED (self_decl) = 1;
  DECL_READ_P (self_decl) = 1;
  TREE_USED (DECL_CHAIN (self_decl)) = 1;
  DECL_READ_P (DECL_CHAIN (self_decl)) = 1;
#ifdef OBJCPLUS
  pop_lang_context ();
#endif

  METHOD_DEFINITION (method) = current_function_decl;

  /* Check consistency...start_function, pushdecl, duplicate_decls.  */

  if (implementation_template != objc_implementation_context)
    {
      tree proto
        = lookup_method_static (implementation_template,
                                METHOD_SEL_NAME (method),
                                ((TREE_CODE (method) == CLASS_METHOD_DECL)
                                 | OBJC_LOOKUP_NO_SUPER));

      if (proto)
        {
          if (!comp_proto_with_proto (method, proto, 1))
            {
              bool type = TREE_CODE (method) == INSTANCE_METHOD_DECL;

              warning_at (DECL_SOURCE_LOCATION (method), 0,
                          "conflicting types for %<%c%s%>",
                          (type ? '-' : '+'),
                          identifier_to_locale (gen_method_decl (method)));
              inform (DECL_SOURCE_LOCATION (proto),
                      "previous declaration of %<%c%s%>",
                      (type ? '-' : '+'),
                      identifier_to_locale (gen_method_decl (proto)));
            }
          else
            {
              /* If the method in the @interface was deprecated, mark
                 the implemented method as deprecated too.  It should
                 never be used for messaging (when the deprecation
                 warnings are produced), but just in case.  */
              if (TREE_DEPRECATED (proto))
                TREE_DEPRECATED (method) = 1;

              /* If the method in the @interface was marked as
                 'noreturn', mark the function implementing the method
                 as 'noreturn' too.  */
              TREE_THIS_VOLATILE (current_function_decl) = TREE_THIS_VOLATILE (proto);
            }
        }
      else
        {
          /* We have a method @implementation even though we did not
             see a corresponding @interface declaration (which is allowed
             by Objective-C rules).  Go ahead and place the method in
             the @interface anyway, so that message dispatch lookups
             will see it.  */
          tree interface = implementation_template;

          if (TREE_CODE (objc_implementation_context)
              == CATEGORY_IMPLEMENTATION_TYPE)
            interface = lookup_category
                        (interface,
                         CLASS_SUPER_NAME (objc_implementation_context));

          if (interface)
            objc_add_method (interface, copy_node (method),
                             TREE_CODE (method) == CLASS_METHOD_DECL, 
                             /* is_optional= */ false);
        }
    }
}

static void *UOBJC_SUPER_scope = 0;

/* _n_Method (id self, SEL sel, ...)
     {
       struct objc_super _S;
       _msgSuper ((_S.self = self, _S.class = _cls, &_S), ...);
     }  */

static tree
get_super_receiver (void)
{
  if (objc_method_context)
    {
      tree super_expr, super_expr_list;

      if (!UOBJC_SUPER_decl)
      {
        UOBJC_SUPER_decl = build_decl (input_location,
                                       VAR_DECL, get_identifier (TAG_SUPER),
                                       objc_super_template);
        /* This prevents `unused variable' warnings when compiling with -Wall.  */
        TREE_USED (UOBJC_SUPER_decl) = 1;
        DECL_READ_P (UOBJC_SUPER_decl) = 1;
        lang_hooks.decls.pushdecl (UOBJC_SUPER_decl);
        finish_decl (UOBJC_SUPER_decl, input_location, NULL_TREE, NULL_TREE,
                     NULL_TREE);
        UOBJC_SUPER_scope = objc_get_current_scope ();
      }

      /* Set receiver to self.  */
      super_expr = objc_build_component_ref (UOBJC_SUPER_decl, self_id);
      super_expr = build_modify_expr (input_location, super_expr, NULL_TREE,
                                      NOP_EXPR, input_location, self_decl,
                                      NULL_TREE);
      super_expr_list = super_expr;

      /* Set class to begin searching.  */
      super_expr = objc_build_component_ref (UOBJC_SUPER_decl,
                                             get_identifier ("super_class"));

      if (TREE_CODE (objc_implementation_context) == CLASS_IMPLEMENTATION_TYPE)
        {
          /* [_cls, __cls]Super are "pre-built" in
             synth_forward_declarations.  */

          super_expr = build_modify_expr (input_location, super_expr,
                                          NULL_TREE, NOP_EXPR,
                                          input_location,
                                          ((TREE_CODE (objc_method_context)
                                            == INSTANCE_METHOD_DECL)
                                           ? ucls_super_ref
                                           : uucls_super_ref),
                                          NULL_TREE);
        }

      else
        /* We have a category.  */
        {
          tree super_name = CLASS_SUPER_NAME (implementation_template);
          tree super_class;

          /* Barf if super used in a category of Object.  */
          if (!super_name)
            {
              error ("no super class declared in interface for %qE",
                     CLASS_NAME (implementation_template));
              return error_mark_node;
            }

          if (flag_next_runtime && !flag_zero_link)
            {
              super_class = objc_get_class_reference (super_name);
              if (TREE_CODE (objc_method_context) == CLASS_METHOD_DECL)
                /* If we are in a class method, we must retrieve the
                   _metaclass_ for the current class, pointed at by
                   the class's "isa" pointer.  The following assumes that
                   "isa" is the first ivar in a class (which it must be).  */
                super_class
                  = build_indirect_ref
                      (input_location,
                       build_c_cast (input_location,
                                     build_pointer_type (objc_class_type),
                                     super_class), RO_UNARY_STAR);
            }
          else
            {
              add_class_reference (super_name);
              super_class = (TREE_CODE (objc_method_context) == INSTANCE_METHOD_DECL
                             ? objc_get_class_decl : objc_get_meta_class_decl);
              assemble_external (super_class);
              super_class
                = build_function_call
                  (input_location,
                   super_class,
                   build_tree_list
                   (NULL_TREE,
                    my_build_string_pointer
                    (IDENTIFIER_LENGTH (super_name) + 1,
                     IDENTIFIER_POINTER (super_name))));
            }

          super_expr
            = build_modify_expr (input_location, super_expr, NULL_TREE,
                                 NOP_EXPR,
                                 input_location,
                                 build_c_cast (input_location, 
                                               TREE_TYPE (super_expr),
                                               super_class),
                                 NULL_TREE);
        }

      super_expr_list = build_compound_expr (input_location, 
                                             super_expr_list, super_expr);

      super_expr = build_unary_op (input_location, 
                                   ADDR_EXPR, UOBJC_SUPER_decl, 0);
      super_expr_list = build_compound_expr (input_location,
                                             super_expr_list, super_expr);

      return super_expr_list;
    }
  else
    {
      error ("[super ...] must appear in a method context");
      return error_mark_node;
    }
}

/* When exiting a scope, sever links to a 'super' declaration (if any)
   therein contained.  */

void
objc_clear_super_receiver (void)
{
  if (objc_method_context
      && UOBJC_SUPER_scope == objc_get_current_scope ()) {
    UOBJC_SUPER_decl = 0;
    UOBJC_SUPER_scope = 0;
  }
}

void
objc_finish_method_definition (tree fndecl)
{
  /* We cannot validly inline ObjC methods, at least not without a language
     extension to declare that a method need not be dynamically
     dispatched, so suppress all thoughts of doing so.  */
  DECL_UNINLINABLE (fndecl) = 1;

#ifndef OBJCPLUS
  /* The C++ front-end will have called finish_function() for us.  */
  finish_function ();
#endif

  METHOD_ENCODING (objc_method_context)
    = encode_method_prototype (objc_method_context);

  /* Required to implement _msgSuper. This must be done AFTER finish_function,
     since the optimizer may find "may be used before set" errors.  */
  objc_method_context = NULL_TREE;

  if (should_call_super_dealloc)
    warning (0, "method possibly missing a [super dealloc] call");
}

/* Given a tree DECL node, produce a printable description of it in the given
   buffer, overwriting the buffer.  */

static char *
gen_declaration (tree decl)
{
  errbuf[0] = '\0';

  if (DECL_P (decl))
    {
      gen_type_name_0 (TREE_TYPE (decl));

      if (DECL_NAME (decl))
        {
          if (!POINTER_TYPE_P (TREE_TYPE (decl)))
            strcat (errbuf, " ");

          strcat (errbuf, IDENTIFIER_POINTER (DECL_NAME (decl)));
        }

      if (DECL_INITIAL (decl)
          && TREE_CODE (DECL_INITIAL (decl)) == INTEGER_CST)
        sprintf (errbuf + strlen (errbuf), ": " HOST_WIDE_INT_PRINT_DEC,
                 TREE_INT_CST_LOW (DECL_INITIAL (decl)));
    }

  return errbuf;
}

/* Given a tree TYPE node, produce a printable description of it in the given
   buffer, overwriting the buffer.  */

static char *
gen_type_name_0 (tree type)
{
  tree orig = type, proto;

  if (TYPE_P (type) && TYPE_NAME (type))
    type = TYPE_NAME (type);
  else if (POINTER_TYPE_P (type) || TREE_CODE (type) == ARRAY_TYPE)
    {
      tree inner = TREE_TYPE (type);

      while (TREE_CODE (inner) == ARRAY_TYPE)
        inner = TREE_TYPE (inner);

      gen_type_name_0 (inner);

      if (!POINTER_TYPE_P (inner))
        strcat (errbuf, " ");

      if (POINTER_TYPE_P (type))
        strcat (errbuf, "*");
      else
        while (type != inner)
          {
            strcat (errbuf, "[");

            if (TYPE_DOMAIN (type))
              {
                char sz[20];

                sprintf (sz, HOST_WIDE_INT_PRINT_DEC,
                         (TREE_INT_CST_LOW
                          (TYPE_MAX_VALUE (TYPE_DOMAIN (type))) + 1));
                strcat (errbuf, sz);
              }

            strcat (errbuf, "]");
            type = TREE_TYPE (type);
          }

      goto exit_function;
    }

  if (TREE_CODE (type) == TYPE_DECL && DECL_NAME (type))
    type = DECL_NAME (type);

  strcat (errbuf, TREE_CODE (type) == IDENTIFIER_NODE
                  ? IDENTIFIER_POINTER (type)
                  : "");

  /* For 'id' and 'Class', adopted protocols are stored in the pointee.  */
  if (objc_is_id (orig))
    orig = TREE_TYPE (orig);

  proto = TYPE_HAS_OBJC_INFO (orig) ? TYPE_OBJC_PROTOCOL_LIST (orig) : NULL_TREE;

  if (proto)
    {
      strcat (errbuf, " <");

      while (proto) {
        strcat (errbuf,
                IDENTIFIER_POINTER (PROTOCOL_NAME (TREE_VALUE (proto))));
        proto = TREE_CHAIN (proto);
        strcat (errbuf, proto ? ", " : ">");
      }
    }

 exit_function:
  return errbuf;
}

static char *
gen_type_name (tree type)
{
  errbuf[0] = '\0';

  return gen_type_name_0 (type);
}

/* Given a method tree, put a printable description into the given
   buffer (overwriting) and return a pointer to the buffer.  */

static char *
gen_method_decl (tree method)
{
  tree chain;

  strcpy (errbuf, "(");  /* NB: Do _not_ call strcat() here.  */
  gen_type_name_0 (TREE_VALUE (TREE_TYPE (method)));
  strcat (errbuf, ")");
  chain = METHOD_SEL_ARGS (method);

  if (chain)
    {
      /* We have a chain of keyword_decls.  */
      do
        {
          if (KEYWORD_KEY_NAME (chain))
            strcat (errbuf, IDENTIFIER_POINTER (KEYWORD_KEY_NAME (chain)));

          strcat (errbuf, ":(");
          gen_type_name_0 (TREE_VALUE (TREE_TYPE (chain)));
          strcat (errbuf, ")");

          strcat (errbuf, IDENTIFIER_POINTER (KEYWORD_ARG_NAME (chain)));
          if ((chain = DECL_CHAIN (chain)))
            strcat (errbuf, " ");
        }
      while (chain);

      if (METHOD_ADD_ARGS (method))
        {
          chain = TREE_CHAIN (METHOD_ADD_ARGS (method));

          /* Know we have a chain of parm_decls.  */
          while (chain)
            {
              strcat (errbuf, ", ");
              gen_type_name_0 (TREE_TYPE (TREE_VALUE (chain)));
              chain = TREE_CHAIN (chain);
            }

          if (METHOD_ADD_ARGS_ELLIPSIS_P (method))
            strcat (errbuf, ", ...");
        }
    }

  else
    /* We have a unary selector.  */
    strcat (errbuf, IDENTIFIER_POINTER (METHOD_SEL_NAME (method)));

  return errbuf;
}
\f
/* Debug info.  */


/* Dump an @interface declaration of the supplied class CHAIN to the
   supplied file FP.  Used to implement the -gen-decls option (which
   prints out an @interface declaration of all classes compiled in
   this run); potentially useful for debugging the compiler too.  */
static void
dump_interface (FILE *fp, tree chain)
{
  /* FIXME: A heap overflow here whenever a method (or ivar)
     declaration is so long that it doesn't fit in the buffer.  The
     code and all the related functions should be rewritten to avoid
     using fixed size buffers.  */
  const char *my_name = IDENTIFIER_POINTER (CLASS_NAME (chain));
  tree ivar_decls = CLASS_RAW_IVARS (chain);
  tree nst_methods = CLASS_NST_METHODS (chain);
  tree cls_methods = CLASS_CLS_METHODS (chain);

  fprintf (fp, "\n@interface %s", my_name);

  /* CLASS_SUPER_NAME is used to store the superclass name for
     classes, and the category name for categories.  */
  if (CLASS_SUPER_NAME (chain))
    {
      const char *name = IDENTIFIER_POINTER (CLASS_SUPER_NAME (chain));

      switch (TREE_CODE (chain))
        {
        case CATEGORY_IMPLEMENTATION_TYPE:
        case CATEGORY_INTERFACE_TYPE:
          fprintf (fp, " (%s)\n", name);
          break;
        default:
          fprintf (fp, " : %s\n", name);
          break;
        }
    }
  else
    fprintf (fp, "\n");

  /* FIXME - the following doesn't seem to work at the moment.  */
  if (ivar_decls)
    {
      fprintf (fp, "{\n");
      do
        {
          fprintf (fp, "\t%s;\n", gen_declaration (ivar_decls));
          ivar_decls = TREE_CHAIN (ivar_decls);
        }
      while (ivar_decls);
      fprintf (fp, "}\n");
    }

  while (nst_methods)
    {
      fprintf (fp, "- %s;\n", gen_method_decl (nst_methods));
      nst_methods = TREE_CHAIN (nst_methods);
    }

  while (cls_methods)
    {
      fprintf (fp, "+ %s;\n", gen_method_decl (cls_methods));
      cls_methods = TREE_CHAIN (cls_methods);
    }

  fprintf (fp, "@end\n");
}

#if 0
/* Produce the pretty printing for an Objective-C method.  This is
   currently unused, but could be handy while reorganizing the pretty
   printing to be more robust.  */
static const char *
objc_pretty_print_method (bool is_class_method,
                          const char *class_name,
                          const char *category_name,
                          const char *selector)
{
  if (category_name)
    {
      char *result = XNEWVEC (char, strlen (class_name) + strlen (category_name) 
                              + strlen (selector) + 7);

      if (is_class_method)
        sprintf (result, "+[%s(%s) %s]", class_name, category_name, selector);
      else
        sprintf (result, "-[%s(%s) %s]", class_name, category_name, selector);

      return result;
    }
  else
    {
      char *result = XNEWVEC (char, strlen (class_name)
                              + strlen (selector) + 5);

      if (is_class_method)
        sprintf (result, "+[%s %s]", class_name, selector);
      else
        sprintf (result, "-[%s %s]", class_name, selector);

      return result;      
    }
}
#endif

/* Demangle function for Objective-C.  Attempt to demangle the
   function name associated with a method (eg, going from
   "_i_NSObject__class" to "-[NSObject class]"); usually for the
   purpose of pretty printing or error messages.  Return the demangled
   name, or NULL if the string is not an Objective-C mangled method
   name.

   Because of how the mangling is done, any method that has a '_' in
   its original name is at risk of being demangled incorrectly.  In
   some cases there are multiple valid ways to demangle a method name
   and there is no way we can decide.

   TODO: objc_demangle() can't always get it right; the right way to
   get this correct for all method names would be to store the
   Objective-C method name somewhere in the function decl.  Then,
   there is no demangling to do; we'd just pull the method name out of
   the decl.  As an additional bonus, when printing error messages we
   could check for such a method name, and if we find it, we know the
   function is actually an Objective-C method and we could print error
   messages saying "In method '+[NSObject class]" instead of "In
   function '+[NSObject class]" as we do now.  */
static const char *
objc_demangle (const char *mangled)
{
  char *demangled, *cp;

  if (mangled[0] == '_' &&
      (mangled[1] == 'i' || mangled[1] == 'c') &&
      mangled[2] == '_')
    {
      cp = demangled = XNEWVEC (char, strlen(mangled) + 2);
      if (mangled[1] == 'i')
        *cp++ = '-';            /* for instance method */
      else
        *cp++ = '+';            /* for class method */
      *cp++ = '[';              /* opening left brace */
      strcpy(cp, mangled+3);    /* tack on the rest of the mangled name */
      while (*cp && *cp == '_')
        cp++;                   /* skip any initial underbars in class name */
      cp = strchr(cp, '_');     /* find first non-initial underbar */
      if (cp == NULL)
        {
          free(demangled);      /* not mangled name */
          return NULL;
        }
      if (cp[1] == '_')  /* easy case: no category name */
        {
          *cp++ = ' ';            /* replace two '_' with one ' ' */
          strcpy(cp, mangled + (cp - demangled) + 2);
        }
      else
        {
          *cp++ = '(';            /* less easy case: category name */
          cp = strchr(cp, '_');
          if (cp == 0)
            {
              free(demangled);    /* not mangled name */
              return NULL;
            }
          *cp++ = ')';
          *cp++ = ' ';            /* overwriting 1st char of method name... */
          strcpy(cp, mangled + (cp - demangled)); /* get it back */
        }
      /* Now we have the method name.  We need to generally replace
         '_' with ':' but trying to preserve '_' if it could only have
         been in the mangled string because it was already in the
         original name.  In cases where it's ambiguous, we assume that
         any '_' originated from a ':'.  */

      /* Initial '_'s in method name can't have been generating by
         converting ':'s.  Skip them.  */
      while (*cp && *cp == '_')
        cp++;

      /* If the method name does not end with '_', then it has no
         arguments and there was no replacement of ':'s with '_'s
         during mangling.  Check for that case, and skip any
         replacement if so.  This at least guarantees that methods
         with no arguments are always demangled correctly (unless the
         original name ends with '_').  */
      if (*(mangled + strlen (mangled) - 1) != '_')
        {
          /* Skip to the end.  */
          for (; *cp; cp++)
            ;
        }
      else
        {
          /* Replace remaining '_' with ':'.  This may get it wrong if
             there were '_'s in the original name.  In most cases it
             is impossible to disambiguate.  */
          for (; *cp; cp++)
            if (*cp == '_')
              *cp = ':';         
        }
      *cp++ = ']';              /* closing right brace */
      *cp++ = 0;                /* string terminator */
      return demangled;
    }
  else
    return NULL;             /* not an objc mangled name */
}

/* Try to pretty-print a decl.  If the 'decl' is an Objective-C
   specific decl, return the printable name for it.  If not, return
   NULL.  */
const char *
objc_maybe_printable_name (tree decl, int v ATTRIBUTE_UNUSED)
{
  switch (TREE_CODE (decl))
    {
    case FUNCTION_DECL:
      return objc_demangle (IDENTIFIER_POINTER (DECL_NAME (decl)));
      break;

      /* The following happens when we are printing a deprecation
         warning for a method.  The warn_deprecation() will end up
         trying to print the decl for INSTANCE_METHOD_DECL or
         CLASS_METHOD_DECL.  It would be nice to be able to print
         "-[NSObject autorelease] is deprecated", but to do that, we'd
         need to store the class and method name in the method decl,
         which we currently don't do.  For now, just return the name
         of the method.  We don't return NULL, because that may
         trigger further attempts to pretty-print the decl in C/C++,
         but they wouldn't know how to pretty-print it.  */
    case INSTANCE_METHOD_DECL:
    case CLASS_METHOD_DECL:
      return IDENTIFIER_POINTER (DECL_NAME (decl));
      break;
      /* This happens when printing a deprecation warning for a
         property.  We may want to consider some sort of pretty
         printing (eg, include the class name where it was declared
         ?).  */
    case PROPERTY_DECL:
      return IDENTIFIER_POINTER (PROPERTY_NAME (decl));
      break;
    default:
      return NULL;
      break;
    }
}

/* Return a printable name for 'decl'.  This first tries
   objc_maybe_printable_name(), and if that fails, it returns the name
   in the decl.  This is used as LANG_HOOKS_DECL_PRINTABLE_NAME for
   Objective-C; in Objective-C++, setting the hook is not enough
   because lots of C++ Front-End code calls cxx_printable_name,
   dump_decl and other C++ functions directly.  So instead we have
   modified dump_decl to call objc_maybe_printable_name directly.  */
const char *
objc_printable_name (tree decl, int v)
{
  const char *demangled_name = objc_maybe_printable_name (decl, v);

  if (demangled_name != NULL)
    return demangled_name;
  else
    return IDENTIFIER_POINTER (DECL_NAME (decl));
}

static void
init_objc (void)
{
  gcc_obstack_init (&util_obstack);
  util_firstobj = (char *) obstack_finish (&util_obstack);

  errbuf = XNEWVEC (char, 1024 * 10);
  hash_init ();
  synth_module_prologue ();
}
\f
static void
finish_objc (void)
{
  struct imp_entry *impent;
  tree chain;
  /* The internally generated initializers appear to have missing braces.
     Don't warn about this.  */
  int save_warn_missing_braces = warn_missing_braces;
  warn_missing_braces = 0;

  /* A missing @end may not be detected by the parser.  */
  if (objc_implementation_context)
    {
      warning (0, "%<@end%> missing in implementation context");
      finish_class (objc_implementation_context);
      objc_ivar_chain = NULL_TREE;
      objc_implementation_context = NULL_TREE;
    }

  /* Process the static instances here because initialization of objc_symtab
     depends on them.  */
  if (objc_static_instances)
    generate_static_references ();

  /* forward declare categories */
  if (cat_count)
    forward_declare_categories ();

  for (impent = imp_list; impent; impent = impent->next)
    {
      objc_implementation_context = impent->imp_context;
      implementation_template = impent->imp_template;

      /* FIXME: This needs reworking to be more obvious.  */

      UOBJC_CLASS_decl = impent->class_decl;
      UOBJC_METACLASS_decl = impent->meta_decl;

      /* Dump the @interface of each class as we compile it, if the
         -gen-decls option is in use.  TODO: Dump the classes in the
         order they were found, rather than in reverse order as we
         are doing now.  */
      if (flag_gen_declaration)
        {
          dump_interface (gen_declaration_file, objc_implementation_context);
        }

      if (TREE_CODE (objc_implementation_context) == CLASS_IMPLEMENTATION_TYPE)
        {
          /* all of the following reference the string pool...  */
          generate_ivar_lists ();
          generate_dispatch_tables ();
          generate_shared_structures (impent);
        }
      else
        {
          generate_dispatch_tables ();
          generate_category (impent);
        }

      impent->class_decl = UOBJC_CLASS_decl;
      impent->meta_decl = UOBJC_METACLASS_decl;
    }

  /* If we are using an array of selectors, we must always
     finish up the array decl even if no selectors were used.  */
  if (flag_next_runtime)
    build_next_selector_translation_table ();
  else
    build_gnu_selector_translation_table ();

  if (protocol_chain)
    generate_protocols ();

  if (flag_next_runtime)
    generate_objc_image_info ();

  if (imp_list || class_names_chain
      || meth_var_names_chain || meth_var_types_chain || sel_ref_chain)
    generate_objc_symtab_decl ();

  /* Arrange for ObjC data structures to be initialized at run time.  */
  if (objc_implementation_context || class_names_chain || objc_static_instances
      || meth_var_names_chain || meth_var_types_chain || sel_ref_chain)
    {
      build_module_descriptor ();

      if (!flag_next_runtime)
        build_module_initializer_routine ();
    }

  /* Dump the class references.  This forces the appropriate classes
     to be linked into the executable image, preserving unix archive
     semantics.  This can be removed when we move to a more dynamically
     linked environment.  */

  for (chain = cls_ref_chain; chain; chain = TREE_CHAIN (chain))
    {
      handle_class_ref (chain);
      if (TREE_PURPOSE (chain))
        generate_classref_translation_entry (chain);
    }

  for (impent = imp_list; impent; impent = impent->next)
    handle_impent (impent);

  if (warn_selector)
    {
      int slot;
      hash hsh;

      /* Run through the selector hash tables and print a warning for any
         selector which has multiple methods.  */

      for (slot = 0; slot < SIZEHASHTABLE; slot++)
        {
          for (hsh = cls_method_hash_list[slot]; hsh; hsh = hsh->next)
            check_duplicates (hsh, 0, 1);
          for (hsh = nst_method_hash_list[slot]; hsh; hsh = hsh->next)
            check_duplicates (hsh, 0, 1);
        }
    }

  warn_missing_braces = save_warn_missing_braces;
}
\f
/* Subroutines of finish_objc.  */

static void
generate_classref_translation_entry (tree chain)
{
  tree expr, decl, type;

  decl = TREE_PURPOSE (chain);
  type = TREE_TYPE (decl);

  expr = add_objc_string (TREE_VALUE (chain), class_names);
  expr = convert (type, expr); /* cast! */

  /* This is a class reference.  It is re-written by the runtime,
     but will be optimized away unless we force it.  */
  DECL_PRESERVE_P (decl) = 1;
  finish_var_decl (decl, expr);
  return;
}

static void
handle_class_ref (tree chain)
{
  const char *name = IDENTIFIER_POINTER (TREE_VALUE (chain));
  char *string = (char *) alloca (strlen (name) + 30);
  tree decl;
  tree exp;

  sprintf (string, "%sobjc_class_name_%s",
           (flag_next_runtime ? "." : "__"), name);

#ifdef ASM_DECLARE_UNRESOLVED_REFERENCE
  if (flag_next_runtime)
    {
      ASM_DECLARE_UNRESOLVED_REFERENCE (asm_out_file, string);
      return;
    }
#endif

  /* Make a decl for this name, so we can use its address in a tree.  */
  decl = build_decl (input_location,
                     VAR_DECL, get_identifier (string), TREE_TYPE (integer_zero_node));
  DECL_EXTERNAL (decl) = 1;
  TREE_PUBLIC (decl) = 1;
  pushdecl (decl);
  finish_var_decl (decl, 0);

  /* Make a decl for the address.  */
  sprintf (string, "%sobjc_class_ref_%s",
           (flag_next_runtime ? "." : "__"), name);
  exp = build1 (ADDR_EXPR, string_type_node, decl);
  decl = build_decl (input_location,
                     VAR_DECL, get_identifier (string), string_type_node);
  TREE_STATIC (decl) = 1;
  TREE_USED (decl) = 1;
  DECL_READ_P (decl) = 1;
  DECL_ARTIFICIAL (decl) = 1;
  DECL_INITIAL (decl) = error_mark_node;
 
  /* We must force the reference.  */
  DECL_PRESERVE_P (decl) = 1;

  pushdecl (decl);
  finish_var_decl (decl, exp);
}

static void
handle_impent (struct imp_entry *impent)
{
  char *string;

  objc_implementation_context = impent->imp_context;
  implementation_template = impent->imp_template;

  switch (TREE_CODE (impent->imp_context))
    {
    case CLASS_IMPLEMENTATION_TYPE:
      {
        const char *const class_name =
          IDENTIFIER_POINTER (CLASS_NAME (impent->imp_context));
        
        string = (char *) alloca (strlen (class_name) + 30);
        
        sprintf (string, "%sobjc_class_name_%s",
                 (flag_next_runtime ? "." : "__"), class_name);
        break;
      }
    case CATEGORY_IMPLEMENTATION_TYPE:
      {
        const char *const class_name =
          IDENTIFIER_POINTER (CLASS_NAME (impent->imp_context));
        const char *const class_super_name =
          IDENTIFIER_POINTER (CLASS_SUPER_NAME (impent->imp_context));
        
        string = (char *) alloca (strlen (class_name)
                                  + strlen (class_super_name) + 30);
        
        /* Do the same for categories.  Even though no references to
           these symbols are generated automatically by the compiler,
           it gives you a handle to pull them into an archive by
           hand.  */
        sprintf (string, "*%sobjc_category_name_%s_%s",
                 (flag_next_runtime ? "." : "__"), class_name, class_super_name);
        break;
      }
    default:
      return;
    }

#ifdef ASM_DECLARE_CLASS_REFERENCE
  if (flag_next_runtime)
    {
      ASM_DECLARE_CLASS_REFERENCE (asm_out_file, string);
      return;
    }
  else
#endif
    {
      tree decl, init;

      init = integer_zero_node;
      decl = build_decl (input_location,
                         VAR_DECL, get_identifier (string), TREE_TYPE (init));
      TREE_PUBLIC (decl) = 1;
      TREE_READONLY (decl) = 1;
      TREE_USED (decl) = 1;
      TREE_CONSTANT (decl) = 1;
      DECL_CONTEXT (decl) = NULL_TREE;
      DECL_ARTIFICIAL (decl) = 1;
      TREE_STATIC (decl) = 1;
      DECL_INITIAL (decl) = error_mark_node; /* A real initializer is coming... */
      /* We must force the reference.  */
      DECL_PRESERVE_P (decl) = 1;

      finish_var_decl(decl, init) ;
    }
}
\f
/* The Fix-and-Continue functionality available in Mac OS X 10.3 and
   later requires that ObjC translation units participating in F&C be
   specially marked.  The following routine accomplishes this.  */

/* static int _OBJC_IMAGE_INFO[2] = { 0, 1 }; */

static void
generate_objc_image_info (void)
{
  tree decl;
  int flags
    = ((flag_replace_objc_classes && imp_count ? 1 : 0)
       | (flag_objc_gc ? 2 : 0));
  VEC(constructor_elt,gc) *v = NULL;
  tree array_type;
  
   if (!flags)
    return; /* No need for an image_info entry.  */
  
  array_type  = build_sized_array_type (integer_type_node, 2);

  decl = start_var_decl (array_type, "_OBJC_IMAGE_INFO");

  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, integer_zero_node);
  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (integer_type_node, flags));
  /* If we need this (determined above) it is because the runtime wants to
     refer to it in a manner hidden from the compiler.  So we must force the 
     output.  */
  DECL_PRESERVE_P (decl) = 1;
  finish_var_decl (decl, objc_build_constructor (TREE_TYPE (decl), v));
}

/* Routine is called to issue diagnostic when reference to a private 
   ivar is made and no other variable with same name is found in 
   current scope.  */
bool
objc_diagnose_private_ivar (tree id)
{
  tree ivar;
  if (!objc_method_context)
    return false;
  ivar = is_ivar (objc_ivar_chain, id);
  if (ivar && is_private (ivar))
    {
      error ("instance variable %qs is declared private", 
             IDENTIFIER_POINTER (id));
      return true;
    }
  return false;
}

/* Look up ID as an instance variable.  OTHER contains the result of
   the C or C++ lookup, which we may want to use instead.  */
/* To use properties inside an instance method, use self.property.  */
tree
objc_lookup_ivar (tree other, tree id)
{
  tree ivar;

  /* If we are not inside of an ObjC method, ivar lookup makes no sense.  */
  if (!objc_method_context)
    return other;

  if (!strcmp (IDENTIFIER_POINTER (id), "super"))
    /* We have a message to super.  */
    return get_super_receiver ();

  /* In a class method, look up an instance variable only as a last
     resort.  */
  if (TREE_CODE (objc_method_context) == CLASS_METHOD_DECL
      && other && other != error_mark_node)
    return other;

  /* Look up the ivar, but do not use it if it is not accessible.  */
  ivar = is_ivar (objc_ivar_chain, id);
  
  if (!ivar || is_private (ivar))
    return other;

  /* In an instance method, a local variable (or parameter) may hide the
     instance variable.  */
  if (TREE_CODE (objc_method_context) == INSTANCE_METHOD_DECL
      && other && other != error_mark_node
#ifdef OBJCPLUS
      && CP_DECL_CONTEXT (other) != global_namespace)
#else
      && !DECL_FILE_SCOPE_P (other))
#endif
    {
      warning (0, "local declaration of %qE hides instance variable", id);

      return other;
    }

  /* At this point, we are either in an instance method with no obscuring
     local definitions, or in a class method with no alternate definitions
     at all.  */
  return build_ivar_reference (id);
}

/* Possibly rewrite a function CALL into an OBJ_TYPE_REF expression.  This
   needs to be done if we are calling a function through a cast.  */

tree
objc_rewrite_function_call (tree function, tree first_param)
{
  if (TREE_CODE (function) == NOP_EXPR
      && TREE_CODE (TREE_OPERAND (function, 0)) == ADDR_EXPR
      && TREE_CODE (TREE_OPERAND (TREE_OPERAND (function, 0), 0))
         == FUNCTION_DECL)
    {
      function = build3 (OBJ_TYPE_REF, TREE_TYPE (function),
                         TREE_OPERAND (function, 0),
                         first_param, size_zero_node);
    }

  return function;
}

/* This is called to "gimplify" a PROPERTY_REF node.  It builds the
   corresponding 'getter' function call.  Note that we assume the
   PROPERTY_REF to be valid since we generated it while parsing.  */
static void
objc_gimplify_property_ref (tree *expr_p)
{
  tree getter = PROPERTY_REF_GETTER_CALL (*expr_p);
  tree call_exp;

  if (getter == NULL_TREE)
    {
      tree property_decl = PROPERTY_REF_PROPERTY_DECL (*expr_p);
      /* This can happen if DECL_ARTIFICIAL (*expr_p), but
         should be impossible for real properties, which always
         have a getter.  */
      error_at (EXPR_LOCATION (*expr_p), "no %qs getter found",
                IDENTIFIER_POINTER (PROPERTY_NAME (property_decl)));
      /* Try to recover from the error to prevent an ICE.  We take
         zero and cast it to the type of the property.  */
      *expr_p = convert (TREE_TYPE (property_decl),
                         integer_zero_node);
      return;
    }

  call_exp = getter;
#ifdef OBJCPLUS
  /* In C++, a getter which returns an aggregate value results in a
     target_expr which initializes a temporary to the call
     expression.  */
  if (TREE_CODE (getter) == TARGET_EXPR)
    {
      gcc_assert (MAYBE_CLASS_TYPE_P (TREE_TYPE (getter)));
      gcc_assert (TREE_CODE (TREE_OPERAND (getter, 0)) == VAR_DECL);
      call_exp = TREE_OPERAND (getter, 1);
    }
#endif
  gcc_assert (TREE_CODE (call_exp) == CALL_EXPR);
  
  *expr_p = call_exp;
}

/* This is called when "gimplifying" the trees.  We need to gimplify
   the Objective-C/Objective-C++ specific trees, then hand over the
   process to C/C++.  */
int
objc_gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
{
  enum tree_code code = TREE_CODE (*expr_p);
  switch (code)
    {
      /* Look for the special case of OBJC_TYPE_REF with the address
         of a function in OBJ_TYPE_REF_EXPR (presumably objc_msgSend
         or one of its cousins).  */
    case OBJ_TYPE_REF:
      if (TREE_CODE (OBJ_TYPE_REF_EXPR (*expr_p)) == ADDR_EXPR
          && TREE_CODE (TREE_OPERAND (OBJ_TYPE_REF_EXPR (*expr_p), 0))
          == FUNCTION_DECL)
        {
          enum gimplify_status r0, r1;

          /* Postincrements in OBJ_TYPE_REF_OBJECT don't affect the
             value of the OBJ_TYPE_REF, so force them to be emitted
             during subexpression evaluation rather than after the
             OBJ_TYPE_REF. This permits objc_msgSend calls in
             Objective C to use direct rather than indirect calls when
             the object expression has a postincrement.  */
          r0 = gimplify_expr (&OBJ_TYPE_REF_OBJECT (*expr_p), pre_p, NULL,
                              is_gimple_val, fb_rvalue);
          r1 = gimplify_expr (&OBJ_TYPE_REF_EXPR (*expr_p), pre_p, post_p,
                              is_gimple_val, fb_rvalue);
          
          return MIN (r0, r1);
        }
      break;
    case PROPERTY_REF:
      objc_gimplify_property_ref (expr_p);
      /* Do not return yet; let C/C++ gimplify the resulting expression.  */
      break;
    default:
      break;
    }

#ifdef OBJCPLUS
  return (enum gimplify_status) cp_gimplify_expr (expr_p, pre_p, post_p);
#else
  return (enum gimplify_status) c_gimplify_expr (expr_p, pre_p, post_p);
#endif
}

/* This routine returns true if TYPE is a valid objc object type,
   suitable for messaging; false otherwise.  If 'accept_class' is
   'true', then a Class object is considered valid for messaging and
   'true' is returned if 'type' refers to a Class.  If 'accept_class'
   is 'false', then a Class object is not considered valid for
   messaging and 'false' is returned in that case.  */

static bool
objc_type_valid_for_messaging (tree type, bool accept_classes)
{
  if (!POINTER_TYPE_P (type))
    return false;

  /* Remove the pointer indirection; don't remove more than one
     otherwise we'd consider "NSObject **" a valid type for messaging,
     which it isn't.  */
  type = TREE_TYPE (type);

  if (TREE_CODE (type) != RECORD_TYPE)
    return false;

  if (objc_is_object_id (type))
    return true;

  if (objc_is_class_id (type))
    return accept_classes;

  if (TYPE_HAS_OBJC_INFO (type))
    return true;

  return false;
}

/* Begin code generation for fast enumeration (foreach) ... */

/* Defines

  struct __objcFastEnumerationState
   {
     unsigned long state;
     id            *itemsPtr;
     unsigned long *mutationsPtr;
     unsigned long extra[5];
   };

   Confusingly enough, NSFastEnumeration is then defined by libraries
   to be the same structure.  
*/

static void
build_fast_enumeration_state_template (void)
{
  tree decls, *chain = NULL;

  /* { */
  objc_fast_enumeration_state_template = objc_start_struct (get_identifier 
                                                            (TAG_FAST_ENUMERATION_STATE));

  /* unsigned long state; */
  decls = add_field_decl (long_unsigned_type_node, "state", &chain);

  /* id            *itemsPtr; */
  add_field_decl (build_pointer_type (objc_object_type), 
                  "itemsPtr", &chain);

  /* unsigned long *mutationsPtr; */
  add_field_decl (build_pointer_type (long_unsigned_type_node), 
                  "mutationsPtr", &chain);

  /* unsigned long extra[5]; */
  add_field_decl (build_sized_array_type (long_unsigned_type_node, 5), 
                  "extra", &chain);

  /* } */
  objc_finish_struct (objc_fast_enumeration_state_template, decls);
}

/*
  'objc_finish_foreach_loop()' generates the code for an Objective-C
  foreach loop.  The 'location' argument is the location of the 'for'
  that starts the loop.  The 'object_expression' is the expression of
  the 'object' that iterates; the 'collection_expression' is the
  expression of the collection that we iterate over (we need to make
  sure we evaluate this only once); the 'for_body' is the set of
  statements to be executed in each iteration; 'break_label' and
  'continue_label' are the break and continue labels which we need to
  emit since the <statements> may be jumping to 'break_label' (if they
  contain 'break') or to 'continue_label' (if they contain
  'continue').

  The syntax is
  
  for (<object expression> in <collection expression>)
    <statements>

  which is compiled into the following blurb:

  {
    id __objc_foreach_collection;
    __objc_fast_enumeration_state __objc_foreach_enum_state;
    unsigned long __objc_foreach_batchsize;
    id __objc_foreach_items[16];
    __objc_foreach_collection = <collection expression>;
    __objc_foreach_enum_state = { 0 };
    __objc_foreach_batchsize = [__objc_foreach_collection countByEnumeratingWithState: &__objc_foreach_enum_state  objects: __objc_foreach_items  count: 16];
    
    if (__objc_foreach_batchsize == 0)
      <object expression> = nil;
    else
      {
        unsigned long __objc_foreach_mutations_pointer = *__objc_foreach_enum_state.mutationsPtr;
        next_batch:
          {
            unsigned long __objc_foreach_index;
            __objc_foreach_index = 0;

            next_object:
            if (__objc_foreach_mutation_pointer != *__objc_foreach_enum_state.mutationsPtr) objc_enumeration_mutation (<collection expression>);
            <object expression> = enumState.itemsPtr[__objc_foreach_index];
            <statements> [PS: inside <statments>, 'break' jumps to break_label and 'continue' jumps to continue_label]

            continue_label:
            __objc_foreach_index++;
            if (__objc_foreach_index < __objc_foreach_batchsize) goto next_object;
            __objc_foreach_batchsize = [__objc_foreach_collection countByEnumeratingWithState: &__objc_foreach_enum_state  objects: __objc_foreach_items  count: 16];
         }
       if (__objc_foreach_batchsize != 0) goto next_batch;
       <object expression> = nil;
       break_label:
      }
  }

  'statements' may contain a 'continue' or 'break' instruction, which
  the user expects to 'continue' or 'break' the entire foreach loop.
  We are provided the labels that 'break' and 'continue' jump to, so
  we place them where we want them to jump to when they pick them.
  
  Optimization TODO: we could cache the IMP of
  countByEnumeratingWithState:objects:count:.
*/

/* If you need to debug objc_finish_foreach_loop(), uncomment the following line.  */
/* #define DEBUG_OBJC_FINISH_FOREACH_LOOP 1 */

#ifdef DEBUG_OBJC_FINISH_FOREACH_LOOP
#include "tree-pretty-print.h"
#endif

void
objc_finish_foreach_loop (location_t location, tree object_expression, tree collection_expression, tree for_body, 
                          tree break_label, tree continue_label)
{
  /* A tree representing the __objcFastEnumerationState struct type,
     or NSFastEnumerationState struct, whatever we are using.  */
  tree objc_fast_enumeration_state_type;

  /* The trees representing the declarations of each of the local variables.  */
  tree objc_foreach_collection_decl;
  tree objc_foreach_enum_state_decl;
  tree objc_foreach_items_decl;
  tree objc_foreach_batchsize_decl;
  tree objc_foreach_mutations_pointer_decl;
  tree objc_foreach_index_decl;

  /* A tree representing the selector countByEnumeratingWithState:objects:count:.  */
  tree selector_name;

  /* A tree representing the local bind.  */
  tree bind;

  /* A tree representing the external 'if (__objc_foreach_batchsize)' */
  tree first_if;

  /* A tree representing the 'else' part of 'first_if'  */
  tree first_else;

  /* A tree representing the 'next_batch' label.  */
  tree next_batch_label_decl;

  /* A tree representing the binding after the 'next_batch' label.  */
  tree next_batch_bind;

  /* A tree representing the 'next_object' label.  */
  tree next_object_label_decl;

  /* Temporary variables.  */
  tree t;
  int i;

  if (flag_objc1_only)
    error_at (location, "fast enumeration is not available in Objective-C 1.0");

  if (object_expression == error_mark_node)
    return;

  if (collection_expression == error_mark_node)
    return;

  if (!objc_type_valid_for_messaging (TREE_TYPE (object_expression), true))
    {
      error ("iterating variable in fast enumeration is not an object");
      return;
    }

  if (!objc_type_valid_for_messaging (TREE_TYPE (collection_expression), true))
    {
      error ("collection in fast enumeration is not an object");
      return;
    }

  /* TODO: Check that object_expression is either a variable
     declaration, or an lvalue.  */

  /* This kludge is an idea from apple.  We use the
     __objcFastEnumerationState struct implicitly defined by the
     compiler, unless a NSFastEnumerationState struct has been defined
     (by a Foundation library such as GNUstep Base) in which case, we
     use that one.
  */
  objc_fast_enumeration_state_type = objc_fast_enumeration_state_template;
  {
    tree objc_NSFastEnumeration_type = lookup_name (get_identifier ("NSFastEnumerationState"));

    if (objc_NSFastEnumeration_type)
      {
        /* TODO: We really need to check that
           objc_NSFastEnumeration_type is the same as ours!  */
        if (TREE_CODE (objc_NSFastEnumeration_type) == TYPE_DECL)
          {
            /* If it's a typedef, use the original type.  */
            if (DECL_ORIGINAL_TYPE (objc_NSFastEnumeration_type))
              objc_fast_enumeration_state_type = DECL_ORIGINAL_TYPE (objc_NSFastEnumeration_type);
            else
              objc_fast_enumeration_state_type = TREE_TYPE (objc_NSFastEnumeration_type);             
          }
      }
  }

  /* { */
  /* Done by c-parser.c.  */

  /* type object; */
  /* Done by c-parser.c.  */

  /*  id __objc_foreach_collection */
  objc_foreach_collection_decl = objc_create_temporary_var (objc_object_type, "__objc_foreach_collection");

  /*  __objcFastEnumerationState __objc_foreach_enum_state; */
  objc_foreach_enum_state_decl = objc_create_temporary_var (objc_fast_enumeration_state_type, "__objc_foreach_enum_state");
  TREE_CHAIN (objc_foreach_enum_state_decl) = objc_foreach_collection_decl;

  /* id __objc_foreach_items[16]; */
  objc_foreach_items_decl = objc_create_temporary_var (build_sized_array_type (objc_object_type, 16), "__objc_foreach_items");
  TREE_CHAIN (objc_foreach_items_decl) = objc_foreach_enum_state_decl;

  /* unsigned long __objc_foreach_batchsize; */
  objc_foreach_batchsize_decl = objc_create_temporary_var (long_unsigned_type_node, "__objc_foreach_batchsize");
  TREE_CHAIN (objc_foreach_batchsize_decl) = objc_foreach_items_decl;

  /* Generate the local variable binding.  */
  bind = build3 (BIND_EXPR, void_type_node, objc_foreach_batchsize_decl, NULL, NULL);
  SET_EXPR_LOCATION (bind, location);
  TREE_SIDE_EFFECTS (bind) = 1;
  
  /*  __objc_foreach_collection = <collection expression>; */
  t = build2 (MODIFY_EXPR, void_type_node, objc_foreach_collection_decl, collection_expression);
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (bind));

  /*  __objc_foreach_enum_state.state = 0; */
  t = build2 (MODIFY_EXPR, void_type_node, objc_build_component_ref (objc_foreach_enum_state_decl, 
                                                                     get_identifier ("state")),
              build_int_cst (long_unsigned_type_node, 0));
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (bind));

  /*  __objc_foreach_enum_state.itemsPtr = NULL; */
  t = build2 (MODIFY_EXPR, void_type_node, objc_build_component_ref (objc_foreach_enum_state_decl, 
                                                                     get_identifier ("itemsPtr")),
              null_pointer_node);
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (bind));

  /*  __objc_foreach_enum_state.mutationsPtr = NULL; */
  t = build2 (MODIFY_EXPR, void_type_node, objc_build_component_ref (objc_foreach_enum_state_decl, 
                                                                     get_identifier ("mutationsPtr")),
              null_pointer_node);
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (bind));

  /*  __objc_foreach_enum_state.extra[0] = 0; */
  /*  __objc_foreach_enum_state.extra[1] = 0; */
  /*  __objc_foreach_enum_state.extra[2] = 0; */
  /*  __objc_foreach_enum_state.extra[3] = 0; */
  /*  __objc_foreach_enum_state.extra[4] = 0; */
  for (i = 0; i < 5 ; i++)
    {
      t = build2 (MODIFY_EXPR, void_type_node,
                  build_array_ref (location, objc_build_component_ref (objc_foreach_enum_state_decl, 
                                                                       get_identifier ("extra")),
                                   build_int_cst (NULL_TREE, i)),
                  build_int_cst (long_unsigned_type_node, 0));
      SET_EXPR_LOCATION (t, location);
      append_to_statement_list (t, &BIND_EXPR_BODY (bind));
    }
    
  /* __objc_foreach_batchsize = [__objc_foreach_collection countByEnumeratingWithState: &__objc_foreach_enum_state  objects: __objc_foreach_items  count: 16]; */
  selector_name = get_identifier ("countByEnumeratingWithState:objects:count:");
#ifdef OBJCPLUS
  t = objc_finish_message_expr (objc_foreach_collection_decl, selector_name,
                                /* Parameters.  */
                                tree_cons    /* &__objc_foreach_enum_state */
                                (NULL_TREE, build_fold_addr_expr_loc (location, objc_foreach_enum_state_decl),
                                 tree_cons   /* __objc_foreach_items  */
                                 (NULL_TREE, objc_foreach_items_decl,
                                  tree_cons  /* 16 */
                                  (NULL_TREE, build_int_cst (NULL_TREE, 16), NULL_TREE))));
#else
  /* In C, we need to decay the __objc_foreach_items array that we are passing.  */
  {
    struct c_expr array;
    array.value = objc_foreach_items_decl;
    t = objc_finish_message_expr (objc_foreach_collection_decl, selector_name,
                                  /* Parameters.  */
                                  tree_cons    /* &__objc_foreach_enum_state */
                                  (NULL_TREE, build_fold_addr_expr_loc (location, objc_foreach_enum_state_decl),
                                   tree_cons   /* __objc_foreach_items  */
                                   (NULL_TREE, default_function_array_conversion (location, array).value,
                                    tree_cons  /* 16 */
                                    (NULL_TREE, build_int_cst (NULL_TREE, 16), NULL_TREE))));
  }
#endif
  t = build2 (MODIFY_EXPR, void_type_node, objc_foreach_batchsize_decl,
              convert (long_unsigned_type_node, t));
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (bind));

  /* if (__objc_foreach_batchsize == 0) */
  first_if = build3 (COND_EXPR, void_type_node, 
                     /* Condition.  */
                     c_fully_fold 
                     (c_common_truthvalue_conversion 
                      (location, 
                       build_binary_op (location,
                                        EQ_EXPR, 
                                        objc_foreach_batchsize_decl,
                                        build_int_cst (long_unsigned_type_node, 0), 1)),
                      false, NULL),
                     /* Then block (we fill it in later).  */
                     NULL_TREE,
                     /* Else block (we fill it in later).  */
                     NULL_TREE);
  SET_EXPR_LOCATION (first_if, location);
  append_to_statement_list (first_if, &BIND_EXPR_BODY (bind));

  /* then <object expression> = nil; */
  t = build2 (MODIFY_EXPR, void_type_node, object_expression, convert (objc_object_type, null_pointer_node));
  SET_EXPR_LOCATION (t, location);
  COND_EXPR_THEN (first_if) = t;

  /* Now we build the 'else' part of the if; once we finish building
     it, we attach it to first_if as the 'else' part.  */

  /* else */
  /* { */

  /* unsigned long __objc_foreach_mutations_pointer; */
  objc_foreach_mutations_pointer_decl = objc_create_temporary_var (long_unsigned_type_node, "__objc_foreach_mutations_pointer");

  /* Generate the local variable binding.  */
  first_else = build3 (BIND_EXPR, void_type_node, objc_foreach_mutations_pointer_decl, NULL, NULL);
  SET_EXPR_LOCATION (first_else, location);
  TREE_SIDE_EFFECTS (first_else) = 1;

  /* __objc_foreach_mutations_pointer = *__objc_foreach_enum_state.mutationsPtr; */
  t = build2 (MODIFY_EXPR, void_type_node, objc_foreach_mutations_pointer_decl, 
              build_indirect_ref (location, objc_build_component_ref (objc_foreach_enum_state_decl, 
                                                                      get_identifier ("mutationsPtr")),
                                  RO_UNARY_STAR));
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (first_else));

  /* next_batch: */
  next_batch_label_decl = create_artificial_label (location);
  t = build1 (LABEL_EXPR, void_type_node, next_batch_label_decl); 
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (first_else));
  
  /* { */

  /* unsigned long __objc_foreach_index; */
  objc_foreach_index_decl = objc_create_temporary_var (long_unsigned_type_node, "__objc_foreach_index");

  /* Generate the local variable binding.  */
  next_batch_bind = build3 (BIND_EXPR, void_type_node, objc_foreach_index_decl, NULL, NULL);
  SET_EXPR_LOCATION (next_batch_bind, location);
  TREE_SIDE_EFFECTS (next_batch_bind) = 1;
  append_to_statement_list (next_batch_bind, &BIND_EXPR_BODY (first_else));

  /* __objc_foreach_index = 0; */
  t = build2 (MODIFY_EXPR, void_type_node, objc_foreach_index_decl,
              build_int_cst (long_unsigned_type_node, 0));
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (next_batch_bind));

  /* next_object: */
  next_object_label_decl = create_artificial_label (location);
  t = build1 (LABEL_EXPR, void_type_node, next_object_label_decl);
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (next_batch_bind));

  /* if (__objc_foreach_mutation_pointer != *__objc_foreach_enum_state.mutationsPtr) objc_enumeration_mutation (<collection expression>); */
  t = build3 (COND_EXPR, void_type_node, 
              /* Condition.  */
              c_fully_fold 
              (c_common_truthvalue_conversion 
               (location, 
                build_binary_op 
                (location,
                 NE_EXPR, 
                 objc_foreach_mutations_pointer_decl,
                 build_indirect_ref (location, 
                                     objc_build_component_ref (objc_foreach_enum_state_decl, 
                                                               get_identifier ("mutationsPtr")),
                                     RO_UNARY_STAR), 1)),
               false, NULL),
              /* Then block.  */
              build_function_call (input_location,
                                   objc_enumeration_mutation_decl,
                                   tree_cons (NULL, collection_expression, NULL)),
              /* Else block.  */
              NULL_TREE);
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (next_batch_bind));

  /* <object expression> = enumState.itemsPtr[__objc_foreach_index]; */
  t = build2 (MODIFY_EXPR, void_type_node, object_expression, 
              build_array_ref (location, objc_build_component_ref (objc_foreach_enum_state_decl, 
                                                                   get_identifier ("itemsPtr")),
                               objc_foreach_index_decl));
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (next_batch_bind));

  /* <statements> [PS: in <statments>, 'break' jumps to break_label and 'continue' jumps to continue_label] */
  append_to_statement_list (for_body, &BIND_EXPR_BODY (next_batch_bind));

  /* continue_label: */
  if (continue_label)
    {
      t = build1 (LABEL_EXPR, void_type_node, continue_label);
      SET_EXPR_LOCATION (t, location);
      append_to_statement_list (t, &BIND_EXPR_BODY (next_batch_bind));
    }

  /* __objc_foreach_index++; */
  t = build2 (MODIFY_EXPR, void_type_node, objc_foreach_index_decl, 
              build_binary_op (location,
                               PLUS_EXPR,
                               objc_foreach_index_decl,
                               build_int_cst (long_unsigned_type_node, 1), 1));
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (next_batch_bind));

  /* if (__objc_foreach_index < __objc_foreach_batchsize) goto next_object; */
  t = build3 (COND_EXPR, void_type_node, 
              /* Condition.  */
              c_fully_fold 
              (c_common_truthvalue_conversion 
               (location, 
                build_binary_op (location,
                                 LT_EXPR, 
                                 objc_foreach_index_decl,
                                 objc_foreach_batchsize_decl, 1)),
               false, NULL),
              /* Then block.  */
              build1 (GOTO_EXPR, void_type_node, next_object_label_decl),
              /* Else block.  */
              NULL_TREE);
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (next_batch_bind));
  
  /* __objc_foreach_batchsize = [__objc_foreach_collection countByEnumeratingWithState: &__objc_foreach_enum_state  objects: __objc_foreach_items  count: 16]; */
#ifdef OBJCPLUS
  t = objc_finish_message_expr (objc_foreach_collection_decl, selector_name,
                                /* Parameters.  */
                                tree_cons    /* &__objc_foreach_enum_state */
                                (NULL_TREE, build_fold_addr_expr_loc (location, objc_foreach_enum_state_decl),
                                 tree_cons   /* __objc_foreach_items  */
                                 (NULL_TREE, objc_foreach_items_decl,
                                  tree_cons  /* 16 */
                                  (NULL_TREE, build_int_cst (NULL_TREE, 16), NULL_TREE))));
#else
  /* In C, we need to decay the __objc_foreach_items array that we are passing.  */
  {
    struct c_expr array;
    array.value = objc_foreach_items_decl;
    t = objc_finish_message_expr (objc_foreach_collection_decl, selector_name,
                                  /* Parameters.  */
                                  tree_cons    /* &__objc_foreach_enum_state */
                                  (NULL_TREE, build_fold_addr_expr_loc (location, objc_foreach_enum_state_decl),
                                   tree_cons   /* __objc_foreach_items  */
                                   (NULL_TREE, default_function_array_conversion (location, array).value,
                                    tree_cons  /* 16 */
                                    (NULL_TREE, build_int_cst (NULL_TREE, 16), NULL_TREE))));
  }
#endif
  t = build2 (MODIFY_EXPR, void_type_node, objc_foreach_batchsize_decl, 
              convert (long_unsigned_type_node, t));
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (next_batch_bind));

  /* } */

  /* if (__objc_foreach_batchsize != 0) goto next_batch; */
  t = build3 (COND_EXPR, void_type_node, 
              /* Condition.  */
              c_fully_fold 
              (c_common_truthvalue_conversion 
               (location, 
                build_binary_op (location,
                                 NE_EXPR, 
                                 objc_foreach_batchsize_decl,
                                 build_int_cst (long_unsigned_type_node, 0), 1)),
               false, NULL),
              /* Then block.  */
              build1 (GOTO_EXPR, void_type_node, next_batch_label_decl),
              /* Else block.  */
              NULL_TREE);
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (first_else));

  /* <object expression> = nil; */
  t = build2 (MODIFY_EXPR, void_type_node, object_expression, convert (objc_object_type, null_pointer_node));
  SET_EXPR_LOCATION (t, location);
  append_to_statement_list (t, &BIND_EXPR_BODY (first_else));

  /* break_label: */
  if (break_label)
    {
      t = build1 (LABEL_EXPR, void_type_node, break_label);
      SET_EXPR_LOCATION (t, location);
      append_to_statement_list (t, &BIND_EXPR_BODY (first_else));
    }

  /* } */
  COND_EXPR_ELSE (first_if) = first_else;

  /* Do the whole thing.  */
  add_stmt (bind);

#ifdef DEBUG_OBJC_FINISH_FOREACH_LOOP
  /* This will print to stderr the whole blurb generated by the
     compiler while compiling (assuming the compiler doesn't crash
     before getting here).
   */
  debug_generic_stmt (bind);
#endif

  /* } */
  /* Done by c-parser.c  */
}

/* Return true if we have an NxString object pointer.  */

bool
objc_string_ref_type_p (tree strp)
{
  tree tmv;
  if (!strp || TREE_CODE (strp) != POINTER_TYPE)
    return false;

  tmv = TYPE_MAIN_VARIANT (TREE_TYPE (strp));
  tmv = OBJC_TYPE_NAME (tmv);
  return (tmv
          && TREE_CODE (tmv) == IDENTIFIER_NODE
          && IDENTIFIER_POINTER (tmv)
          && !strncmp (IDENTIFIER_POINTER (tmv), "NSString", 8));
}

/* At present the behavior of this is undefined and it does nothing.  */
void
objc_check_format_arg (tree ARG_UNUSED (format_arg), 
                       tree ARG_UNUSED (args_list))
{
}

#include "gt-objc-objc-act.h"