PR c/529

[pf3gnuchains/gcc-fork.git] / gcc / c-decl.c

/* Process declarations and variables for C compiler.
   Copyright (C) 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
   2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.

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 2, 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 COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */

/* Process declarations and symbol lookup for C front end.
   Also constructs types; the standard scalar types at initialization,
   and structure, union, array and enum types when they are declared.  */

/* ??? not all decl nodes are given the most useful possible
   line numbers.  For example, the CONST_DECLs for enum values.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "input.h"
#include "tm.h"
#include "intl.h"
#include "tree.h"
#include "tree-inline.h"
#include "rtl.h"
#include "flags.h"
#include "function.h"
#include "output.h"
#include "expr.h"
#include "c-tree.h"
#include "toplev.h"
#include "ggc.h"
#include "tm_p.h"
#include "cpplib.h"
#include "target.h"
#include "debug.h"
#include "opts.h"
#include "timevar.h"
#include "c-common.h"
#include "c-pragma.h"
#include "langhooks.h"
#include "tree-mudflap.h"
#include "tree-gimple.h"
#include "diagnostic.h"
#include "tree-dump.h"
#include "cgraph.h"
#include "hashtab.h"
#include "libfuncs.h"
#include "except.h"
#include "langhooks-def.h"
#include "pointer-set.h"

/* In grokdeclarator, distinguish syntactic contexts of declarators.  */
enum decl_context
{ NORMAL,                       /* Ordinary declaration */
  FUNCDEF,                      /* Function definition */
  PARM,                         /* Declaration of parm before function body */
  FIELD,                        /* Declaration inside struct or union */
  TYPENAME};                    /* Typename (inside cast or sizeof)  */

\f
/* Nonzero if we have seen an invalid cross reference
   to a struct, union, or enum, but not yet printed the message.  */
tree pending_invalid_xref;

/* File and line to appear in the eventual error message.  */
location_t pending_invalid_xref_location;

/* True means we've initialized exception handling.  */
bool c_eh_initialized_p;

/* While defining an enum type, this is 1 plus the last enumerator
   constant value.  Note that will do not have to save this or `enum_overflow'
   around nested function definition since such a definition could only
   occur in an enum value expression and we don't use these variables in
   that case.  */

static tree enum_next_value;

/* Nonzero means that there was overflow computing enum_next_value.  */

static int enum_overflow;

/* The file and line that the prototype came from if this is an
   old-style definition; used for diagnostics in
   store_parm_decls_oldstyle.  */

static location_t current_function_prototype_locus;

/* Whether this prototype was built-in.  */

static bool current_function_prototype_built_in;

/* The argument type information of this prototype.  */

static tree current_function_prototype_arg_types;

/* The argument information structure for the function currently being
   defined.  */

static struct c_arg_info *current_function_arg_info;

/* The obstack on which parser and related data structures, which are
   not live beyond their top-level declaration or definition, are
   allocated.  */
struct obstack parser_obstack;

/* The current statement tree.  */

static GTY(()) struct stmt_tree_s c_stmt_tree;

/* State saving variables.  */
tree c_break_label;
tree c_cont_label;

/* Linked list of TRANSLATION_UNIT_DECLS for the translation units
   included in this invocation.  Note that the current translation
   unit is not included in this list.  */

static GTY(()) tree all_translation_units;

/* A list of decls to be made automatically visible in each file scope.  */
static GTY(()) tree visible_builtins;

/* Set to 0 at beginning of a function definition, set to 1 if
   a return statement that specifies a return value is seen.  */

int current_function_returns_value;

/* Set to 0 at beginning of a function definition, set to 1 if
   a return statement with no argument is seen.  */

int current_function_returns_null;

/* Set to 0 at beginning of a function definition, set to 1 if
   a call to a noreturn function is seen.  */

int current_function_returns_abnormally;

/* Set to nonzero by `grokdeclarator' for a function
   whose return type is defaulted, if warnings for this are desired.  */

static int warn_about_return_type;

/* Nonzero when starting a function declared `extern inline'.  */

static int current_extern_inline;

/* Nonzero when the current toplevel function contains a declaration
   of a nested function which is never defined.  */

static bool undef_nested_function;

/* True means global_bindings_p should return false even if the scope stack
   says we are in file scope.  */
bool c_override_global_bindings_to_false;

\f
/* Each c_binding structure describes one binding of an identifier to
   a decl.  All the decls in a scope - irrespective of namespace - are
   chained together by the ->prev field, which (as the name implies)
   runs in reverse order.  All the decls in a given namespace bound to
   a given identifier are chained by the ->shadowed field, which runs
   from inner to outer scopes.

   The ->decl field usually points to a DECL node, but there are two
   exceptions.  In the namespace of type tags, the bound entity is a
   RECORD_TYPE, UNION_TYPE, or ENUMERAL_TYPE node.  If an undeclared
   identifier is encountered, it is bound to error_mark_node to
   suppress further errors about that identifier in the current
   function.

   The ->type field stores the type of the declaration in this scope;
   if NULL, the type is the type of the ->decl field.  This is only of
   relevance for objects with external or internal linkage which may
   be redeclared in inner scopes, forming composite types that only
   persist for the duration of those scopes.  In the external scope,
   this stores the composite of all the types declared for this
   object, visible or not.  The ->inner_comp field (used only at file
   scope) stores whether an incomplete array type at file scope was
   completed at an inner scope to an array size other than 1.

   The depth field is copied from the scope structure that holds this
   decl.  It is used to preserve the proper ordering of the ->shadowed
   field (see bind()) and also for a handful of special-case checks.
   Finally, the invisible bit is true for a decl which should be
   ignored for purposes of normal name lookup, and the nested bit is
   true for a decl that's been bound a second time in an inner scope;
   in all such cases, the binding in the outer scope will have its
   invisible bit true.  */

struct c_binding GTY((chain_next ("%h.prev")))
{
  tree decl;                    /* the decl bound */
  tree type;                    /* the type in this scope */
  tree id;                      /* the identifier it's bound to */
  struct c_binding *prev;       /* the previous decl in this scope */
  struct c_binding *shadowed;   /* the innermost decl shadowed by this one */
  unsigned int depth : 28;      /* depth of this scope */
  BOOL_BITFIELD invisible : 1;  /* normal lookup should ignore this binding */
  BOOL_BITFIELD nested : 1;     /* do not set DECL_CONTEXT when popping */
  BOOL_BITFIELD inner_comp : 1; /* incomplete array completed in inner scope */
  /* one free bit */
};
#define B_IN_SCOPE(b1, b2) ((b1)->depth == (b2)->depth)
#define B_IN_CURRENT_SCOPE(b) ((b)->depth == current_scope->depth)
#define B_IN_FILE_SCOPE(b) ((b)->depth == 1 /*file_scope->depth*/)
#define B_IN_EXTERNAL_SCOPE(b) ((b)->depth == 0 /*external_scope->depth*/)

#define I_SYMBOL_BINDING(node) \
  (((struct lang_identifier *) IDENTIFIER_NODE_CHECK(node))->symbol_binding)
#define I_SYMBOL_DECL(node) \
 (I_SYMBOL_BINDING(node) ? I_SYMBOL_BINDING(node)->decl : 0)

#define I_TAG_BINDING(node) \
  (((struct lang_identifier *) IDENTIFIER_NODE_CHECK(node))->tag_binding)
#define I_TAG_DECL(node) \
 (I_TAG_BINDING(node) ? I_TAG_BINDING(node)->decl : 0)

#define I_LABEL_BINDING(node) \
  (((struct lang_identifier *) IDENTIFIER_NODE_CHECK(node))->label_binding)
#define I_LABEL_DECL(node) \
 (I_LABEL_BINDING(node) ? I_LABEL_BINDING(node)->decl : 0)

/* Each C symbol points to three linked lists of c_binding structures.
   These describe the values of the identifier in the three different
   namespaces defined by the language.  */

struct lang_identifier GTY(())
{
  struct c_common_identifier common_id;
  struct c_binding *symbol_binding; /* vars, funcs, constants, typedefs */
  struct c_binding *tag_binding;    /* struct/union/enum tags */
  struct c_binding *label_binding;  /* labels */
};

/* Validate c-lang.c's assumptions.  */
extern char C_SIZEOF_STRUCT_LANG_IDENTIFIER_isnt_accurate
[(sizeof(struct lang_identifier) == C_SIZEOF_STRUCT_LANG_IDENTIFIER) ? 1 : -1];

/* The resulting tree type.  */

union lang_tree_node
  GTY((desc ("TREE_CODE (&%h.generic) == IDENTIFIER_NODE"),
       chain_next ("TREE_CODE (&%h.generic) == INTEGER_TYPE ? (union lang_tree_node *) TYPE_NEXT_VARIANT (&%h.generic) : (union lang_tree_node *) TREE_CHAIN (&%h.generic)")))
{
  union tree_node GTY ((tag ("0"),
                        desc ("tree_node_structure (&%h)")))
    generic;
  struct lang_identifier GTY ((tag ("1"))) identifier;
};

/* Each c_scope structure describes the complete contents of one
   scope.  Four scopes are distinguished specially: the innermost or
   current scope, the innermost function scope, the file scope (always
   the second to outermost) and the outermost or external scope.

   Most declarations are recorded in the current scope.

   All normal label declarations are recorded in the innermost
   function scope, as are bindings of undeclared identifiers to
   error_mark_node.  (GCC permits nested functions as an extension,
   hence the 'innermost' qualifier.)  Explicitly declared labels
   (using the __label__ extension) appear in the current scope.

   Being in the file scope (current_scope == file_scope) causes
   special behavior in several places below.  Also, under some
   conditions the Objective-C front end records declarations in the
   file scope even though that isn't the current scope.

   All declarations with external linkage are recorded in the external
   scope, even if they aren't visible there; this models the fact that
   such declarations are visible to the entire program, and (with a
   bit of cleverness, see pushdecl) allows diagnosis of some violations
   of C99 6.2.2p7 and 6.2.7p2:

     If, within the same translation unit, the same identifier appears
     with both internal and external linkage, the behavior is
     undefined.

     All declarations that refer to the same object or function shall
     have compatible type; otherwise, the behavior is undefined.

   Initially only the built-in declarations, which describe compiler
   intrinsic functions plus a subset of the standard library, are in
   this scope.

   The order of the blocks list matters, and it is frequently appended
   to.  To avoid having to walk all the way to the end of the list on
   each insertion, or reverse the list later, we maintain a pointer to
   the last list entry.  (FIXME: It should be feasible to use a reversed
   list here.)

   The bindings list is strictly in reverse order of declarations;
   pop_scope relies on this.  */


struct c_scope GTY((chain_next ("%h.outer")))
{
  /* The scope containing this one.  */
  struct c_scope *outer;

  /* The next outermost function scope.  */
  struct c_scope *outer_function;

  /* All bindings in this scope.  */
  struct c_binding *bindings;

  /* For each scope (except the global one), a chain of BLOCK nodes
     for all the scopes that were entered and exited one level down.  */
  tree blocks;
  tree blocks_last;

  /* The depth of this scope.  Used to keep the ->shadowed chain of
     bindings sorted innermost to outermost.  */
  unsigned int depth : 28;

  /* True if we are currently filling this scope with parameter
     declarations.  */
  BOOL_BITFIELD parm_flag : 1;

  /* True if we already complained about forward parameter decls
     in this scope.  This prevents double warnings on
     foo (int a; int b; ...)  */
  BOOL_BITFIELD warned_forward_parm_decls : 1;

  /* True if this is the outermost block scope of a function body.
     This scope contains the parameters, the local variables declared
     in the outermost block, and all the labels (except those in
     nested functions, or declared at block scope with __label__).  */
  BOOL_BITFIELD function_body : 1;

  /* True means make a BLOCK for this scope no matter what.  */
  BOOL_BITFIELD keep : 1;
};

/* The scope currently in effect.  */

static GTY(()) struct c_scope *current_scope;

/* The innermost function scope.  Ordinary (not explicitly declared)
   labels, bindings to error_mark_node, and the lazily-created
   bindings of __func__ and its friends get this scope.  */

static GTY(()) struct c_scope *current_function_scope;

/* The C file scope.  This is reset for each input translation unit.  */

static GTY(()) struct c_scope *file_scope;

/* The outermost scope.  This is used for all declarations with
   external linkage, and only these, hence the name.  */

static GTY(()) struct c_scope *external_scope;

/* A chain of c_scope structures awaiting reuse.  */

static GTY((deletable)) struct c_scope *scope_freelist;

/* A chain of c_binding structures awaiting reuse.  */

static GTY((deletable)) struct c_binding *binding_freelist;

/* Append VAR to LIST in scope SCOPE.  */
#define SCOPE_LIST_APPEND(scope, list, decl) do {       \
  struct c_scope *s_ = (scope);                         \
  tree d_ = (decl);                                     \
  if (s_->list##_last)                                  \
    TREE_CHAIN (s_->list##_last) = d_;                  \
  else                                                  \
    s_->list = d_;                                      \
  s_->list##_last = d_;                                 \
} while (0)

/* Concatenate FROM in scope FSCOPE onto TO in scope TSCOPE.  */
#define SCOPE_LIST_CONCAT(tscope, to, fscope, from) do {        \
  struct c_scope *t_ = (tscope);                                \
  struct c_scope *f_ = (fscope);                                \
  if (t_->to##_last)                                            \
    TREE_CHAIN (t_->to##_last) = f_->from;                      \
  else                                                          \
    t_->to = f_->from;                                          \
  t_->to##_last = f_->from##_last;                              \
} while (0)

/* True means unconditionally make a BLOCK for the next scope pushed.  */

static bool keep_next_level_flag;

/* True means the next call to push_scope will be the outermost scope
   of a function body, so do not push a new scope, merely cease
   expecting parameter decls.  */

static bool next_is_function_body;

/* Functions called automatically at the beginning and end of execution.  */

static GTY(()) tree static_ctors;
static GTY(()) tree static_dtors;

/* Forward declarations.  */
static tree lookup_name_in_scope (tree, struct c_scope *);
static tree c_make_fname_decl (tree, int);
static tree grokdeclarator (const struct c_declarator *,
                            struct c_declspecs *,
                            enum decl_context, bool, tree *);
static tree grokparms (struct c_arg_info *, bool);
static void layout_array_type (tree);
\f
/* T is a statement.  Add it to the statement-tree.  This is the
   C/ObjC version--C++ has a slightly different version of this
   function.  */

tree
add_stmt (tree t)
{
  enum tree_code code = TREE_CODE (t);

  if (EXPR_P (t) && code != LABEL_EXPR)
    {
      if (!EXPR_HAS_LOCATION (t))
        SET_EXPR_LOCATION (t, input_location);
    }

  if (code == LABEL_EXPR || code == CASE_LABEL_EXPR)
    STATEMENT_LIST_HAS_LABEL (cur_stmt_list) = 1;

  /* Add T to the statement-tree.  Non-side-effect statements need to be
     recorded during statement expressions.  */
  append_to_statement_list_force (t, &cur_stmt_list);

  return t;
}
\f
/* States indicating how grokdeclarator() should handle declspecs marked
   with __attribute__((deprecated)).  An object declared as
   __attribute__((deprecated)) suppresses warnings of uses of other
   deprecated items.  */

enum deprecated_states {
  DEPRECATED_NORMAL,
  DEPRECATED_SUPPRESS
};

static enum deprecated_states deprecated_state = DEPRECATED_NORMAL;

void
c_print_identifier (FILE *file, tree node, int indent)
{
  print_node (file, "symbol", I_SYMBOL_DECL (node), indent + 4);
  print_node (file, "tag", I_TAG_DECL (node), indent + 4);
  print_node (file, "label", I_LABEL_DECL (node), indent + 4);
  if (C_IS_RESERVED_WORD (node))
    {
      tree rid = ridpointers[C_RID_CODE (node)];
      indent_to (file, indent + 4);
      fprintf (file, "rid " HOST_PTR_PRINTF " \"%s\"",
               (void *) rid, IDENTIFIER_POINTER (rid));
    }
}

/* Establish a binding between NAME, an IDENTIFIER_NODE, and DECL,
   which may be any of several kinds of DECL or TYPE or error_mark_node,
   in the scope SCOPE.  */
static void
bind (tree name, tree decl, struct c_scope *scope, bool invisible, bool nested)
{
  struct c_binding *b, **here;

  if (binding_freelist)
    {
      b = binding_freelist;
      binding_freelist = b->prev;
    }
  else
    b = GGC_NEW (struct c_binding);

  b->shadowed = 0;
  b->decl = decl;
  b->id = name;
  b->depth = scope->depth;
  b->invisible = invisible;
  b->nested = nested;
  b->inner_comp = 0;

  b->type = 0;

  b->prev = scope->bindings;
  scope->bindings = b;

  if (!name)
    return;

  switch (TREE_CODE (decl))
    {
    case LABEL_DECL:     here = &I_LABEL_BINDING (name);   break;
    case ENUMERAL_TYPE:
    case UNION_TYPE:
    case RECORD_TYPE:    here = &I_TAG_BINDING (name);     break;
    case VAR_DECL:
    case FUNCTION_DECL:
    case TYPE_DECL:
    case CONST_DECL:
    case PARM_DECL:
    case ERROR_MARK:     here = &I_SYMBOL_BINDING (name);  break;

    default:
      gcc_unreachable ();
    }

  /* Locate the appropriate place in the chain of shadowed decls
     to insert this binding.  Normally, scope == current_scope and
     this does nothing.  */
  while (*here && (*here)->depth > scope->depth)
    here = &(*here)->shadowed;

  b->shadowed = *here;
  *here = b;
}

/* Clear the binding structure B, stick it on the binding_freelist,
   and return the former value of b->prev.  This is used by pop_scope
   and get_parm_info to iterate destructively over all the bindings
   from a given scope.  */
static struct c_binding *
free_binding_and_advance (struct c_binding *b)
{
  struct c_binding *prev = b->prev;

  memset (b, 0, sizeof (struct c_binding));
  b->prev = binding_freelist;
  binding_freelist = b;

  return prev;
}

\f
/* Hook called at end of compilation to assume 1 elt
   for a file-scope tentative array defn that wasn't complete before.  */

void
c_finish_incomplete_decl (tree decl)
{
  if (TREE_CODE (decl) == VAR_DECL)
    {
      tree type = TREE_TYPE (decl);
      if (type != error_mark_node
          && TREE_CODE (type) == ARRAY_TYPE
          && !DECL_EXTERNAL (decl)
          && TYPE_DOMAIN (type) == 0)
        {
          warning (0, "array %q+D assumed to have one element", decl);

          complete_array_type (&TREE_TYPE (decl), NULL_TREE, true);

          layout_decl (decl, 0);
        }
    }
}
\f
/* The Objective-C front-end often needs to determine the current scope.  */

void *
objc_get_current_scope (void)
{
  return current_scope;
}

/* The following function is used only by Objective-C.  It needs to live here
   because it accesses the innards of c_scope.  */

void
objc_mark_locals_volatile (void *enclosing_blk)
{
  struct c_scope *scope;
  struct c_binding *b;

  for (scope = current_scope;
       scope && scope != enclosing_blk;
       scope = scope->outer)
    {
      for (b = scope->bindings; b; b = b->prev)
        objc_volatilize_decl (b->decl);

      /* Do not climb up past the current function.  */
      if (scope->function_body)
        break;
    }
}

/* Nonzero if we are currently in file scope.  */

int
global_bindings_p (void)
{
  return current_scope == file_scope && !c_override_global_bindings_to_false;
}

void
keep_next_level (void)
{
  keep_next_level_flag = true;
}

/* Identify this scope as currently being filled with parameters.  */

void
declare_parm_level (void)
{
  current_scope->parm_flag = true;
}

void
push_scope (void)
{
  if (next_is_function_body)
    {
      /* This is the transition from the parameters to the top level
         of the function body.  These are the same scope
         (C99 6.2.1p4,6) so we do not push another scope structure.
         next_is_function_body is set only by store_parm_decls, which
         in turn is called when and only when we are about to
         encounter the opening curly brace for the function body.

         The outermost block of a function always gets a BLOCK node,
         because the debugging output routines expect that each
         function has at least one BLOCK.  */
      current_scope->parm_flag         = false;
      current_scope->function_body     = true;
      current_scope->keep              = true;
      current_scope->outer_function    = current_function_scope;
      current_function_scope           = current_scope;

      keep_next_level_flag = false;
      next_is_function_body = false;
    }
  else
    {
      struct c_scope *scope;
      if (scope_freelist)
        {
          scope = scope_freelist;
          scope_freelist = scope->outer;
        }
      else
        scope = GGC_CNEW (struct c_scope);

      scope->keep          = keep_next_level_flag;
      scope->outer         = current_scope;
      scope->depth         = current_scope ? (current_scope->depth + 1) : 0;

      /* Check for scope depth overflow.  Unlikely (2^28 == 268,435,456) but
         possible.  */
      if (current_scope && scope->depth == 0)
        {
          scope->depth--;
          sorry ("GCC supports only %u nested scopes", scope->depth);
        }

      current_scope        = scope;
      keep_next_level_flag = false;
    }
}

/* Set the TYPE_CONTEXT of all of TYPE's variants to CONTEXT.  */

static void
set_type_context (tree type, tree context)
{
  for (type = TYPE_MAIN_VARIANT (type); type;
       type = TYPE_NEXT_VARIANT (type))
    TYPE_CONTEXT (type) = context;
}

/* Exit a scope.  Restore the state of the identifier-decl mappings
   that were in effect when this scope was entered.  Return a BLOCK
   node containing all the DECLs in this scope that are of interest
   to debug info generation.  */

tree
pop_scope (void)
{
  struct c_scope *scope = current_scope;
  tree block, context, p;
  struct c_binding *b;

  bool functionbody = scope->function_body;
  bool keep = functionbody || scope->keep || scope->bindings;

  c_end_vm_scope (scope->depth);

  /* If appropriate, create a BLOCK to record the decls for the life
     of this function.  */
  block = 0;
  if (keep)
    {
      block = make_node (BLOCK);
      BLOCK_SUBBLOCKS (block) = scope->blocks;
      TREE_USED (block) = 1;

      /* In each subblock, record that this is its superior.  */
      for (p = scope->blocks; p; p = TREE_CHAIN (p))
        BLOCK_SUPERCONTEXT (p) = block;

      BLOCK_VARS (block) = 0;
    }

  /* The TYPE_CONTEXTs for all of the tagged types belonging to this
     scope must be set so that they point to the appropriate
     construct, i.e.  either to the current FUNCTION_DECL node, or
     else to the BLOCK node we just constructed.

     Note that for tagged types whose scope is just the formal
     parameter list for some function type specification, we can't
     properly set their TYPE_CONTEXTs here, because we don't have a
     pointer to the appropriate FUNCTION_TYPE node readily available
     to us.  For those cases, the TYPE_CONTEXTs of the relevant tagged
     type nodes get set in `grokdeclarator' as soon as we have created
     the FUNCTION_TYPE node which will represent the "scope" for these
     "parameter list local" tagged types.  */
  if (scope->function_body)
    context = current_function_decl;
  else if (scope == file_scope)
    {
      tree file_decl = build_decl (TRANSLATION_UNIT_DECL, 0, 0);
      TREE_CHAIN (file_decl) = all_translation_units;
      all_translation_units = file_decl;
      context = file_decl;
    }
  else
    context = block;

  /* Clear all bindings in this scope.  */
  for (b = scope->bindings; b; b = free_binding_and_advance (b))
    {
      p = b->decl;
      switch (TREE_CODE (p))
        {
        case LABEL_DECL:
          /* Warnings for unused labels, errors for undefined labels.  */
          if (TREE_USED (p) && !DECL_INITIAL (p))
            {
              error ("label %q+D used but not defined", p);
              DECL_INITIAL (p) = error_mark_node;
            }
          else if (!TREE_USED (p) && warn_unused_label)
            {
              if (DECL_INITIAL (p))
                warning (0, "label %q+D defined but not used", p);
              else
                warning (0, "label %q+D declared but not defined", p);
            }
          /* Labels go in BLOCK_VARS.  */
          TREE_CHAIN (p) = BLOCK_VARS (block);
          BLOCK_VARS (block) = p;
          gcc_assert (I_LABEL_BINDING (b->id) == b);
          I_LABEL_BINDING (b->id) = b->shadowed;
          break;

        case ENUMERAL_TYPE:
        case UNION_TYPE:
        case RECORD_TYPE:
          set_type_context (p, context);

          /* Types may not have tag-names, in which case the type
             appears in the bindings list with b->id NULL.  */
          if (b->id)
            {
              gcc_assert (I_TAG_BINDING (b->id) == b);
              I_TAG_BINDING (b->id) = b->shadowed;
            }
          break;

        case FUNCTION_DECL:
          /* Propagate TREE_ADDRESSABLE from nested functions to their
             containing functions.  */
          if (!TREE_ASM_WRITTEN (p)
              && DECL_INITIAL (p) != 0
              && TREE_ADDRESSABLE (p)
              && DECL_ABSTRACT_ORIGIN (p) != 0
              && DECL_ABSTRACT_ORIGIN (p) != p)
            TREE_ADDRESSABLE (DECL_ABSTRACT_ORIGIN (p)) = 1;
          if (!DECL_EXTERNAL (p)
              && DECL_INITIAL (p) == 0)
            {
              error ("nested function %q+D declared but never defined", p);
              undef_nested_function = true;
            }
          goto common_symbol;

        case VAR_DECL:
          /* Warnings for unused variables.  */
          if (!TREE_USED (p)
              && !DECL_IN_SYSTEM_HEADER (p)
              && DECL_NAME (p)
              && !DECL_ARTIFICIAL (p)
              && scope != file_scope
              && scope != external_scope) 
            warning (OPT_Wunused_variable, "unused variable %q+D", p);

          if (b->inner_comp)
            {
              error ("type of array %q+D completed incompatibly with"
                     " implicit initialization", p);
            }

          /* Fall through.  */
        case TYPE_DECL:
        case CONST_DECL:
        common_symbol:
          /* All of these go in BLOCK_VARS, but only if this is the
             binding in the home scope.  */
          if (!b->nested)
            {
              TREE_CHAIN (p) = BLOCK_VARS (block);
              BLOCK_VARS (block) = p;
            }
          /* If this is the file scope, and we are processing more
             than one translation unit in this compilation, set
             DECL_CONTEXT of each decl to the TRANSLATION_UNIT_DECL.
             This makes same_translation_unit_p work, and causes
             static declarations to be given disambiguating suffixes.  */
          if (scope == file_scope && num_in_fnames > 1)
            {
              DECL_CONTEXT (p) = context;
              if (TREE_CODE (p) == TYPE_DECL)
                set_type_context (TREE_TYPE (p), context);
            }

          /* Fall through.  */
          /* Parameters go in DECL_ARGUMENTS, not BLOCK_VARS, and have
             already been put there by store_parm_decls.  Unused-
             parameter warnings are handled by function.c.
             error_mark_node obviously does not go in BLOCK_VARS and
             does not get unused-variable warnings.  */
        case PARM_DECL:
        case ERROR_MARK:
          /* It is possible for a decl not to have a name.  We get
             here with b->id NULL in this case.  */
          if (b->id)
            {
              gcc_assert (I_SYMBOL_BINDING (b->id) == b);
              I_SYMBOL_BINDING (b->id) = b->shadowed;
              if (b->shadowed && b->shadowed->type)
                TREE_TYPE (b->shadowed->decl) = b->shadowed->type;
            }
          break;

        default:
          gcc_unreachable ();
        }
    }


  /* Dispose of the block that we just made inside some higher level.  */
  if ((scope->function_body || scope == file_scope) && context)
    {
      DECL_INITIAL (context) = block;
      BLOCK_SUPERCONTEXT (block) = context;
    }
  else if (scope->outer)
    {
      if (block)
        SCOPE_LIST_APPEND (scope->outer, blocks, block);
      /* If we did not make a block for the scope just exited, any
         blocks made for inner scopes must be carried forward so they
         will later become subblocks of something else.  */
      else if (scope->blocks)
        SCOPE_LIST_CONCAT (scope->outer, blocks, scope, blocks);
    }

  /* Pop the current scope, and free the structure for reuse.  */
  current_scope = scope->outer;
  if (scope->function_body)
    current_function_scope = scope->outer_function;

  memset (scope, 0, sizeof (struct c_scope));
  scope->outer = scope_freelist;
  scope_freelist = scope;

  return block;
}

void
push_file_scope (void)
{
  tree decl;

  if (file_scope)
    return;

  push_scope ();
  file_scope = current_scope;

  start_fname_decls ();

  for (decl = visible_builtins; decl; decl = TREE_CHAIN (decl))
    bind (DECL_NAME (decl), decl, file_scope,
          /*invisible=*/false, /*nested=*/true);
}

void
pop_file_scope (void)
{
  /* In case there were missing closebraces, get us back to the global
     binding level.  */
  while (current_scope != file_scope)
    pop_scope ();

  /* __FUNCTION__ is defined at file scope ("").  This
     call may not be necessary as my tests indicate it
     still works without it.  */
  finish_fname_decls ();

  /* This is the point to write out a PCH if we're doing that.
     In that case we do not want to do anything else.  */
  if (pch_file)
    {
      c_common_write_pch ();
      return;
    }

  /* Pop off the file scope and close this translation unit.  */
  pop_scope ();
  file_scope = 0;

  maybe_apply_pending_pragma_weaks ();
  cgraph_finalize_compilation_unit ();
}

/* Insert BLOCK at the end of the list of subblocks of the current
   scope.  This is used when a BIND_EXPR is expanded, to handle the
   BLOCK node inside the BIND_EXPR.  */

void
insert_block (tree block)
{
  TREE_USED (block) = 1;
  SCOPE_LIST_APPEND (current_scope, blocks, block);
}
\f
/* Push a definition or a declaration of struct, union or enum tag "name".
   "type" should be the type node.
   We assume that the tag "name" is not already defined.

   Note that the definition may really be just a forward reference.
   In that case, the TYPE_SIZE will be zero.  */

static void
pushtag (tree name, tree type)
{
  /* Record the identifier as the type's name if it has none.  */
  if (name && !TYPE_NAME (type))
    TYPE_NAME (type) = name;
  bind (name, type, current_scope, /*invisible=*/false, /*nested=*/false);

  /* Create a fake NULL-named TYPE_DECL node whose TREE_TYPE will be the
     tagged type we just added to the current scope.  This fake
     NULL-named TYPE_DECL node helps dwarfout.c to know when it needs
     to output a representation of a tagged type, and it also gives
     us a convenient place to record the "scope start" address for the
     tagged type.  */

  TYPE_STUB_DECL (type) = pushdecl (build_decl (TYPE_DECL, NULL_TREE, type));

  /* An approximation for now, so we can tell this is a function-scope tag.
     This will be updated in pop_scope.  */
  TYPE_CONTEXT (type) = DECL_CONTEXT (TYPE_STUB_DECL (type));
}
\f
/* Subroutine of compare_decls.  Allow harmless mismatches in return
   and argument types provided that the type modes match.  This function
   return a unified type given a suitable match, and 0 otherwise.  */

static tree
match_builtin_function_types (tree newtype, tree oldtype)
{
  tree newrettype, oldrettype;
  tree newargs, oldargs;
  tree trytype, tryargs;

  /* Accept the return type of the new declaration if same modes.  */
  oldrettype = TREE_TYPE (oldtype);
  newrettype = TREE_TYPE (newtype);

  if (TYPE_MODE (oldrettype) != TYPE_MODE (newrettype))
    return 0;

  oldargs = TYPE_ARG_TYPES (oldtype);
  newargs = TYPE_ARG_TYPES (newtype);
  tryargs = newargs;

  while (oldargs || newargs)
    {
      if (!oldargs
          || !newargs
          || !TREE_VALUE (oldargs)
          || !TREE_VALUE (newargs)
          || TYPE_MODE (TREE_VALUE (oldargs))
             != TYPE_MODE (TREE_VALUE (newargs)))
        return 0;

      oldargs = TREE_CHAIN (oldargs);
      newargs = TREE_CHAIN (newargs);
    }

  trytype = build_function_type (newrettype, tryargs);
  return build_type_attribute_variant (trytype, TYPE_ATTRIBUTES (oldtype));
}

/* Subroutine of diagnose_mismatched_decls.  Check for function type
   mismatch involving an empty arglist vs a nonempty one and give clearer
   diagnostics.  */
static void
diagnose_arglist_conflict (tree newdecl, tree olddecl,
                           tree newtype, tree oldtype)
{
  tree t;

  if (TREE_CODE (olddecl) != FUNCTION_DECL
      || !comptypes (TREE_TYPE (oldtype), TREE_TYPE (newtype))
      || !((TYPE_ARG_TYPES (oldtype) == 0 && DECL_INITIAL (olddecl) == 0)
           ||
           (TYPE_ARG_TYPES (newtype) == 0 && DECL_INITIAL (newdecl) == 0)))
    return;

  t = TYPE_ARG_TYPES (oldtype);
  if (t == 0)
    t = TYPE_ARG_TYPES (newtype);
  for (; t; t = TREE_CHAIN (t))
    {
      tree type = TREE_VALUE (t);

      if (TREE_CHAIN (t) == 0
          && TYPE_MAIN_VARIANT (type) != void_type_node)
        {
          inform ("a parameter list with an ellipsis can%'t match "
                  "an empty parameter name list declaration");
          break;
        }

      if (c_type_promotes_to (type) != type)
        {
          inform ("an argument type that has a default promotion can%'t match "
                  "an empty parameter name list declaration");
          break;
        }
    }
}

/* Another subroutine of diagnose_mismatched_decls.  OLDDECL is an
   old-style function definition, NEWDECL is a prototype declaration.
   Diagnose inconsistencies in the argument list.  Returns TRUE if
   the prototype is compatible, FALSE if not.  */
static bool
validate_proto_after_old_defn (tree newdecl, tree newtype, tree oldtype)
{
  tree newargs, oldargs;
  int i;

#define END_OF_ARGLIST(t) ((t) == void_type_node)

  oldargs = TYPE_ACTUAL_ARG_TYPES (oldtype);
  newargs = TYPE_ARG_TYPES (newtype);
  i = 1;

  for (;;)
    {
      tree oldargtype = TYPE_MAIN_VARIANT (TREE_VALUE (oldargs));
      tree newargtype = TYPE_MAIN_VARIANT (TREE_VALUE (newargs));

      if (END_OF_ARGLIST (oldargtype) && END_OF_ARGLIST (newargtype))
        break;

      /* Reaching the end of just one list means the two decls don't
         agree on the number of arguments.  */
      if (END_OF_ARGLIST (oldargtype))
        {
          error ("prototype for %q+D declares more arguments "
                 "than previous old-style definition", newdecl);
          return false;
        }
      else if (END_OF_ARGLIST (newargtype))
        {
          error ("prototype for %q+D declares fewer arguments "
                 "than previous old-style definition", newdecl);
          return false;
        }

      /* Type for passing arg must be consistent with that declared
         for the arg.  */
      else if (!comptypes (oldargtype, newargtype))
        {
          error ("prototype for %q+D declares argument %d"
                 " with incompatible type",
                 newdecl, i);
          return false;
        }

      oldargs = TREE_CHAIN (oldargs);
      newargs = TREE_CHAIN (newargs);
      i++;
    }

  /* If we get here, no errors were found, but do issue a warning
     for this poor-style construct.  */
  warning (0, "prototype for %q+D follows non-prototype definition",
           newdecl);
  return true;
#undef END_OF_ARGLIST
}

/* Subroutine of diagnose_mismatched_decls.  Report the location of DECL,
   first in a pair of mismatched declarations, using the diagnostic
   function DIAG.  */
static void
locate_old_decl (tree decl, void (*diag)(const char *, ...) ATTRIBUTE_GCC_CDIAG(1,2))
{
  if (TREE_CODE (decl) == FUNCTION_DECL && DECL_BUILT_IN (decl))
    ;
  else if (DECL_INITIAL (decl))
    diag (G_("previous definition of %q+D was here"), decl);
  else if (C_DECL_IMPLICIT (decl))
    diag (G_("previous implicit declaration of %q+D was here"), decl);
  else
    diag (G_("previous declaration of %q+D was here"), decl);
}

/* Subroutine of duplicate_decls.  Compare NEWDECL to OLDDECL.
   Returns true if the caller should proceed to merge the two, false
   if OLDDECL should simply be discarded.  As a side effect, issues
   all necessary diagnostics for invalid or poor-style combinations.
   If it returns true, writes the types of NEWDECL and OLDDECL to
   *NEWTYPEP and *OLDTYPEP - these may have been adjusted from
   TREE_TYPE (NEWDECL, OLDDECL) respectively.  */

static bool
diagnose_mismatched_decls (tree newdecl, tree olddecl,
                           tree *newtypep, tree *oldtypep)
{
  tree newtype, oldtype;
  bool pedwarned = false;
  bool warned = false;
  bool retval = true;

#define DECL_EXTERN_INLINE(DECL) (DECL_DECLARED_INLINE_P (DECL)  \
                                  && DECL_EXTERNAL (DECL))

  /* If we have error_mark_node for either decl or type, just discard
     the previous decl - we're in an error cascade already.  */
  if (olddecl == error_mark_node || newdecl == error_mark_node)
    return false;
  *oldtypep = oldtype = TREE_TYPE (olddecl);
  *newtypep = newtype = TREE_TYPE (newdecl);
  if (oldtype == error_mark_node || newtype == error_mark_node)
    return false;

  /* Two different categories of symbol altogether.  This is an error
     unless OLDDECL is a builtin.  OLDDECL will be discarded in any case.  */
  if (TREE_CODE (olddecl) != TREE_CODE (newdecl))
    {
      if (!(TREE_CODE (olddecl) == FUNCTION_DECL
            && DECL_BUILT_IN (olddecl)
            && !C_DECL_DECLARED_BUILTIN (olddecl)))
        {
          error ("%q+D redeclared as different kind of symbol", newdecl);
          locate_old_decl (olddecl, error);
        }
      else if (TREE_PUBLIC (newdecl))
        warning (0, "built-in function %q+D declared as non-function",
                 newdecl);
      else
        warning (OPT_Wshadow, "declaration of %q+D shadows "
                 "a built-in function", newdecl);
      return false;
    }

  /* Enumerators have no linkage, so may only be declared once in a
     given scope.  */
  if (TREE_CODE (olddecl) == CONST_DECL)
    {
      error ("redeclaration of enumerator %q+D", newdecl);
      locate_old_decl (olddecl, error);
      return false;
    }

  if (!comptypes (oldtype, newtype))
    {
      if (TREE_CODE (olddecl) == FUNCTION_DECL
          && DECL_BUILT_IN (olddecl) && !C_DECL_DECLARED_BUILTIN (olddecl))
        {
          /* Accept harmless mismatch in function types.
             This is for the ffs and fprintf builtins.  */
          tree trytype = match_builtin_function_types (newtype, oldtype);

          if (trytype && comptypes (newtype, trytype))
            *oldtypep = oldtype = trytype;
          else
            {
              /* If types don't match for a built-in, throw away the
                 built-in.  No point in calling locate_old_decl here, it
                 won't print anything.  */
              warning (0, "conflicting types for built-in function %q+D",
                       newdecl);
              return false;
            }
        }
      else if (TREE_CODE (olddecl) == FUNCTION_DECL
               && DECL_IS_BUILTIN (olddecl))
        {
          /* A conflicting function declaration for a predeclared
             function that isn't actually built in.  Objective C uses
             these.  The new declaration silently overrides everything
             but the volatility (i.e. noreturn) indication.  See also
             below.  FIXME: Make Objective C use normal builtins.  */
          TREE_THIS_VOLATILE (newdecl) |= TREE_THIS_VOLATILE (olddecl);
          return false;
        }
      /* Permit void foo (...) to match int foo (...) if the latter is
         the definition and implicit int was used.  See
         c-torture/compile/920625-2.c.  */
      else if (TREE_CODE (newdecl) == FUNCTION_DECL && DECL_INITIAL (newdecl)
               && TYPE_MAIN_VARIANT (TREE_TYPE (oldtype)) == void_type_node
               && TYPE_MAIN_VARIANT (TREE_TYPE (newtype)) == integer_type_node
               && C_FUNCTION_IMPLICIT_INT (newdecl) && !DECL_INITIAL (olddecl))
        {
          pedwarn ("conflicting types for %q+D", newdecl);
          /* Make sure we keep void as the return type.  */
          TREE_TYPE (newdecl) = *newtypep = newtype = oldtype;
          C_FUNCTION_IMPLICIT_INT (newdecl) = 0;
          pedwarned = true;
        }
      /* Permit void foo (...) to match an earlier call to foo (...) with
         no declared type (thus, implicitly int).  */
      else if (TREE_CODE (newdecl) == FUNCTION_DECL
               && TYPE_MAIN_VARIANT (TREE_TYPE (newtype)) == void_type_node
               && TYPE_MAIN_VARIANT (TREE_TYPE (oldtype)) == integer_type_node
               && C_DECL_IMPLICIT (olddecl) && !DECL_INITIAL (olddecl))
        {
          pedwarn ("conflicting types for %q+D", newdecl);
          /* Make sure we keep void as the return type.  */
          TREE_TYPE (olddecl) = *oldtypep = oldtype = newtype;
          pedwarned = true;
        }
      else
        {
          if (TYPE_QUALS (newtype) != TYPE_QUALS (oldtype))
            error ("conflicting type qualifiers for %q+D", newdecl);
          else
            error ("conflicting types for %q+D", newdecl);
          diagnose_arglist_conflict (newdecl, olddecl, newtype, oldtype);
          locate_old_decl (olddecl, error);
          return false;
        }
    }

  /* Redeclaration of a type is a constraint violation (6.7.2.3p1),
     but silently ignore the redeclaration if either is in a system
     header.  (Conflicting redeclarations were handled above.)  */
  if (TREE_CODE (newdecl) == TYPE_DECL)
    {
      if (DECL_IN_SYSTEM_HEADER (newdecl) || DECL_IN_SYSTEM_HEADER (olddecl))
        return true;  /* Allow OLDDECL to continue in use.  */

      error ("redefinition of typedef %q+D", newdecl);
      locate_old_decl (olddecl, error);
      return false;
    }

  /* Function declarations can either be 'static' or 'extern' (no
     qualifier is equivalent to 'extern' - C99 6.2.2p5) and therefore
     can never conflict with each other on account of linkage (6.2.2p4).
     Multiple definitions are not allowed (6.9p3,5) but GCC permits
     two definitions if one is 'extern inline' and one is not.  The non-
     extern-inline definition supersedes the extern-inline definition.  */

  else if (TREE_CODE (newdecl) == FUNCTION_DECL)
    {
      /* If you declare a built-in function name as static, or
         define the built-in with an old-style definition (so we
         can't validate the argument list) the built-in definition is
         overridden, but optionally warn this was a bad choice of name.  */
      if (DECL_BUILT_IN (olddecl)
          && !C_DECL_DECLARED_BUILTIN (olddecl)
          && (!TREE_PUBLIC (newdecl)
              || (DECL_INITIAL (newdecl)
                  && !TYPE_ARG_TYPES (TREE_TYPE (newdecl)))))
        {
          warning (OPT_Wshadow, "declaration of %q+D shadows "
                   "a built-in function", newdecl);
          /* Discard the old built-in function.  */
          return false;
        }

      if (DECL_INITIAL (newdecl))
        {
          if (DECL_INITIAL (olddecl))
            {
              /* If both decls are in the same TU and the new declaration
                 isn't overriding an extern inline reject the new decl.
                 When we handle c99 style inline rules we'll want to reject
                 the following:

                 DECL_EXTERN_INLINE (olddecl)
                 && !DECL_EXTERN_INLINE (newdecl)

                 if they're in the same translation unit. Until we implement
                 the full semantics we accept the construct.  */
              if (!(DECL_EXTERN_INLINE (olddecl)
                    && !DECL_EXTERN_INLINE (newdecl))
                  && same_translation_unit_p (newdecl, olddecl))
                {
                  error ("redefinition of %q+D", newdecl);
                  locate_old_decl (olddecl, error);
                  return false;
                }
            }
        }
      /* If we have a prototype after an old-style function definition,
         the argument types must be checked specially.  */
      else if (DECL_INITIAL (olddecl)
               && !TYPE_ARG_TYPES (oldtype) && TYPE_ARG_TYPES (newtype)
               && TYPE_ACTUAL_ARG_TYPES (oldtype)
               && !validate_proto_after_old_defn (newdecl, newtype, oldtype))
        {
          locate_old_decl (olddecl, error);
          return false;
        }
      /* A non-static declaration (even an "extern") followed by a
         static declaration is undefined behavior per C99 6.2.2p3-5,7.
         The same is true for a static forward declaration at block
         scope followed by a non-static declaration/definition at file
         scope.  Static followed by non-static at the same scope is
         not undefined behavior, and is the most convenient way to get
         some effects (see e.g.  what unwind-dw2-fde-glibc.c does to
         the definition of _Unwind_Find_FDE in unwind-dw2-fde.c), but
         we do diagnose it if -Wtraditional.  */
      if (TREE_PUBLIC (olddecl) && !TREE_PUBLIC (newdecl))
        {
          /* Two exceptions to the rule.  If olddecl is an extern
             inline, or a predeclared function that isn't actually
             built in, newdecl silently overrides olddecl.  The latter
             occur only in Objective C; see also above.  (FIXME: Make
             Objective C use normal builtins.)  */
          if (!DECL_IS_BUILTIN (olddecl)
              && !DECL_EXTERN_INLINE (olddecl))
            {
              error ("static declaration of %q+D follows "
                     "non-static declaration", newdecl);
              locate_old_decl (olddecl, error);
            }
          return false;
        }
      else if (TREE_PUBLIC (newdecl) && !TREE_PUBLIC (olddecl))
        {
          if (DECL_CONTEXT (olddecl))
            {
              error ("non-static declaration of %q+D follows "
                     "static declaration", newdecl);
              locate_old_decl (olddecl, error);
              return false;
            }
          else if (warn_traditional)
            {
              warning (OPT_Wtraditional, "non-static declaration of %q+D "
                       "follows static declaration", newdecl);
              warned = true;
            }
        }
    }
  else if (TREE_CODE (newdecl) == VAR_DECL)
    {
      /* Only variables can be thread-local, and all declarations must
         agree on this property.  */
      if (DECL_THREAD_LOCAL_P (newdecl) != DECL_THREAD_LOCAL_P (olddecl))
        {
          if (DECL_THREAD_LOCAL_P (newdecl))
            error ("thread-local declaration of %q+D follows "
                   "non-thread-local declaration", newdecl);
          else
            error ("non-thread-local declaration of %q+D follows "
                   "thread-local declaration", newdecl);

          locate_old_decl (olddecl, error);
          return false;
        }

      /* Multiple initialized definitions are not allowed (6.9p3,5).  */
      if (DECL_INITIAL (newdecl) && DECL_INITIAL (olddecl))
        {
          error ("redefinition of %q+D", newdecl);
          locate_old_decl (olddecl, error);
          return false;
        }

      /* Objects declared at file scope: if the first declaration had
         external linkage (even if it was an external reference) the
         second must have external linkage as well, or the behavior is
         undefined.  If the first declaration had internal linkage, then
         the second must too, or else be an external reference (in which
         case the composite declaration still has internal linkage).
         As for function declarations, we warn about the static-then-
         extern case only for -Wtraditional.  See generally 6.2.2p3-5,7.  */
      if (DECL_FILE_SCOPE_P (newdecl)
          && TREE_PUBLIC (newdecl) != TREE_PUBLIC (olddecl))
        {
          if (DECL_EXTERNAL (newdecl))
            {
              if (!DECL_FILE_SCOPE_P (olddecl))
                {
                  error ("extern declaration of %q+D follows "
                         "declaration with no linkage", newdecl);
                  locate_old_decl (olddecl, error);
                  return false;
                }
              else if (warn_traditional)
                {
                  warning (OPT_Wtraditional, "non-static declaration of %q+D "
                           "follows static declaration", newdecl);
                  warned = true;
                }
            }
          else
            {
              if (TREE_PUBLIC (newdecl))
                error ("non-static declaration of %q+D follows "
                       "static declaration", newdecl);
              else
                error ("static declaration of %q+D follows "
                       "non-static declaration", newdecl);

              locate_old_decl (olddecl, error);
              return false;
            }
        }
      /* Two objects with the same name declared at the same block
         scope must both be external references (6.7p3).  */
      else if (!DECL_FILE_SCOPE_P (newdecl))
        {
          if (DECL_EXTERNAL (newdecl))
            {
              /* Extern with initializer at block scope, which will
                 already have received an error.  */
            }
          else if (DECL_EXTERNAL (olddecl))
            {
              error ("declaration of %q+D with no linkage follows "
                     "extern declaration", newdecl);
              locate_old_decl (olddecl, error);
            }
          else
            {
              error ("redeclaration of %q+D with no linkage", newdecl);
              locate_old_decl (olddecl, error);
            }

          return false;
        }
    }

  /* warnings */
  /* All decls must agree on a visibility.  */
  if (CODE_CONTAINS_STRUCT (TREE_CODE (newdecl), TS_DECL_WITH_VIS) 
      && DECL_VISIBILITY_SPECIFIED (newdecl) && DECL_VISIBILITY_SPECIFIED (olddecl)
      && DECL_VISIBILITY (newdecl) != DECL_VISIBILITY (olddecl))
    {
      warning (0, "redeclaration of %q+D with different visibility "
               "(old visibility preserved)", newdecl);
      warned = true;
    }

  if (TREE_CODE (newdecl) == FUNCTION_DECL)
    {
      /* Diagnose inline __attribute__ ((noinline)) which is silly.  */
      if (DECL_DECLARED_INLINE_P (newdecl)
          && lookup_attribute ("noinline", DECL_ATTRIBUTES (olddecl)))
        {
          warning (OPT_Wattributes, "inline declaration of %qD follows "
                   "declaration with attribute noinline", newdecl);
          warned = true;
        }
      else if (DECL_DECLARED_INLINE_P (olddecl)
               && lookup_attribute ("noinline", DECL_ATTRIBUTES (newdecl)))
        {
          warning (OPT_Wattributes, "declaration of %q+D with attribute "
                   "noinline follows inline declaration ", newdecl);
          warned = true;
        }

      /* Inline declaration after use or definition.
         ??? Should we still warn about this now we have unit-at-a-time
         mode and can get it right?
         Definitely don't complain if the decls are in different translation
         units.  */
      if (DECL_DECLARED_INLINE_P (newdecl) && !DECL_DECLARED_INLINE_P (olddecl)
          && same_translation_unit_p (olddecl, newdecl))
        {
          if (TREE_USED (olddecl))
            {
              warning (0, "%q+D declared inline after being called", olddecl);
              warned = true;
            }
          else if (DECL_INITIAL (olddecl))
            {
              warning (0, "%q+D declared inline after its definition", olddecl);
              warned = true;
            }
        }
    }
  else /* PARM_DECL, VAR_DECL */
    {
      /* Redeclaration of a parameter is a constraint violation (this is
         not explicitly stated, but follows from C99 6.7p3 [no more than
         one declaration of the same identifier with no linkage in the
         same scope, except type tags] and 6.2.2p6 [parameters have no
         linkage]).  We must check for a forward parameter declaration,
         indicated by TREE_ASM_WRITTEN on the old declaration - this is
         an extension, the mandatory diagnostic for which is handled by
         mark_forward_parm_decls.  */

      if (TREE_CODE (newdecl) == PARM_DECL
          && (!TREE_ASM_WRITTEN (olddecl) || TREE_ASM_WRITTEN (newdecl)))
        {
          error ("redefinition of parameter %q+D", newdecl);
          locate_old_decl (olddecl, error);
          return false;
        }
    }

  /* Optional warning for completely redundant decls.  */
  if (!warned && !pedwarned
      && warn_redundant_decls
      /* Don't warn about a function declaration followed by a
         definition.  */
      && !(TREE_CODE (newdecl) == FUNCTION_DECL
           && DECL_INITIAL (newdecl) && !DECL_INITIAL (olddecl))
      /* Don't warn about redundant redeclarations of builtins.  */
      && !(TREE_CODE (newdecl) == FUNCTION_DECL
           && !DECL_BUILT_IN (newdecl)
           && DECL_BUILT_IN (olddecl)
           && !C_DECL_DECLARED_BUILTIN (olddecl))
      /* Don't warn about an extern followed by a definition.  */
      && !(DECL_EXTERNAL (olddecl) && !DECL_EXTERNAL (newdecl))
      /* Don't warn about forward parameter decls.  */
      && !(TREE_CODE (newdecl) == PARM_DECL
           && TREE_ASM_WRITTEN (olddecl) && !TREE_ASM_WRITTEN (newdecl)))
    {
      warning (OPT_Wredundant_decls, "redundant redeclaration of %q+D",
               newdecl);
      warned = true;
    }

  /* Report location of previous decl/defn in a consistent manner.  */
  if (warned || pedwarned)
    locate_old_decl (olddecl, pedwarned ? pedwarn : warning0);

#undef DECL_EXTERN_INLINE

  return retval;
}

/* Subroutine of duplicate_decls.  NEWDECL has been found to be
   consistent with OLDDECL, but carries new information.  Merge the
   new information into OLDDECL.  This function issues no
   diagnostics.  */

static void
merge_decls (tree newdecl, tree olddecl, tree newtype, tree oldtype)
{
  int new_is_definition = (TREE_CODE (newdecl) == FUNCTION_DECL
                           && DECL_INITIAL (newdecl) != 0);
  int new_is_prototype = (TREE_CODE (newdecl) == FUNCTION_DECL
                          && TYPE_ARG_TYPES (TREE_TYPE (newdecl)) != 0);
  int old_is_prototype = (TREE_CODE (olddecl) == FUNCTION_DECL
                          && TYPE_ARG_TYPES (TREE_TYPE (olddecl)) != 0);

  /* For real parm decl following a forward decl, rechain the old decl
     in its new location and clear TREE_ASM_WRITTEN (it's not a
     forward decl anymore).  */
  if (TREE_CODE (newdecl) == PARM_DECL
      && TREE_ASM_WRITTEN (olddecl) && !TREE_ASM_WRITTEN (newdecl))
    {
      struct c_binding *b, **here;

      for (here = &current_scope->bindings; *here; here = &(*here)->prev)
        if ((*here)->decl == olddecl)
          goto found;
      gcc_unreachable ();

    found:
      b = *here;
      *here = b->prev;
      b->prev = current_scope->bindings;
      current_scope->bindings = b;

      TREE_ASM_WRITTEN (olddecl) = 0;
    }

  DECL_ATTRIBUTES (newdecl)
    = targetm.merge_decl_attributes (olddecl, newdecl);

  /* Merge the data types specified in the two decls.  */
  TREE_TYPE (newdecl)
    = TREE_TYPE (olddecl)
    = composite_type (newtype, oldtype);

  /* Lay the type out, unless already done.  */
  if (!comptypes (oldtype, TREE_TYPE (newdecl)))
    {
      if (TREE_TYPE (newdecl) != error_mark_node)
        layout_type (TREE_TYPE (newdecl));
      if (TREE_CODE (newdecl) != FUNCTION_DECL
          && TREE_CODE (newdecl) != TYPE_DECL
          && TREE_CODE (newdecl) != CONST_DECL)
        layout_decl (newdecl, 0);
    }
  else
    {
      /* Since the type is OLDDECL's, make OLDDECL's size go with.  */
      DECL_SIZE (newdecl) = DECL_SIZE (olddecl);
      DECL_SIZE_UNIT (newdecl) = DECL_SIZE_UNIT (olddecl);
      DECL_MODE (newdecl) = DECL_MODE (olddecl);
      if (TREE_CODE (olddecl) != FUNCTION_DECL)
        if (DECL_ALIGN (olddecl) > DECL_ALIGN (newdecl))
          {
            DECL_ALIGN (newdecl) = DECL_ALIGN (olddecl);
            DECL_USER_ALIGN (newdecl) |= DECL_ALIGN (olddecl);
          }
    }


  /* Merge the type qualifiers.  */
  if (TREE_READONLY (newdecl))
    TREE_READONLY (olddecl) = 1;

  if (TREE_THIS_VOLATILE (newdecl))
    {
      TREE_THIS_VOLATILE (olddecl) = 1;
      if (TREE_CODE (newdecl) == VAR_DECL)
        make_var_volatile (newdecl);
    }

  /* Merge deprecatedness.  */
  if (TREE_DEPRECATED (newdecl))
    TREE_DEPRECATED (olddecl) = 1;

  /* Keep source location of definition rather than declaration and of
     prototype rather than non-prototype unless that prototype is
     built-in.  */
  if ((DECL_INITIAL (newdecl) == 0 && DECL_INITIAL (olddecl) != 0)
      || (old_is_prototype && !new_is_prototype
          && !C_DECL_BUILTIN_PROTOTYPE (olddecl)))
    DECL_SOURCE_LOCATION (newdecl) = DECL_SOURCE_LOCATION (olddecl);

  /* Merge the unused-warning information.  */
  if (DECL_IN_SYSTEM_HEADER (olddecl))
    DECL_IN_SYSTEM_HEADER (newdecl) = 1;
  else if (DECL_IN_SYSTEM_HEADER (newdecl))
    DECL_IN_SYSTEM_HEADER (olddecl) = 1;

  /* Merge the initialization information.  */
   if (DECL_INITIAL (newdecl) == 0)
    DECL_INITIAL (newdecl) = DECL_INITIAL (olddecl);

   if (CODE_CONTAINS_STRUCT (TREE_CODE (olddecl), TS_DECL_WITH_VIS))
     {
       /* Merge the section attribute.
          We want to issue an error if the sections conflict but that must be
          done later in decl_attributes since we are called before attributes
          are assigned.  */
       if (DECL_SECTION_NAME (newdecl) == NULL_TREE)
         DECL_SECTION_NAME (newdecl) = DECL_SECTION_NAME (olddecl);
       
       /* Copy the assembler name.
          Currently, it can only be defined in the prototype.  */
       COPY_DECL_ASSEMBLER_NAME (olddecl, newdecl);

       /* Use visibility of whichever declaration had it specified */
       if (DECL_VISIBILITY_SPECIFIED (olddecl))
         {
           DECL_VISIBILITY (newdecl) = DECL_VISIBILITY (olddecl);
           DECL_VISIBILITY_SPECIFIED (newdecl) = 1;
         }
       
       if (TREE_CODE (newdecl) == FUNCTION_DECL)
         {
           DECL_STATIC_CONSTRUCTOR(newdecl) |= DECL_STATIC_CONSTRUCTOR(olddecl);
           DECL_STATIC_DESTRUCTOR (newdecl) |= DECL_STATIC_DESTRUCTOR (olddecl);
           DECL_NO_LIMIT_STACK (newdecl) |= DECL_NO_LIMIT_STACK (olddecl);
           DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (newdecl)
             |= DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (olddecl);
           TREE_THIS_VOLATILE (newdecl) |= TREE_THIS_VOLATILE (olddecl);
           TREE_READONLY (newdecl) |= TREE_READONLY (olddecl);
           DECL_IS_MALLOC (newdecl) |= DECL_IS_MALLOC (olddecl);
           DECL_IS_PURE (newdecl) |= DECL_IS_PURE (olddecl);
           DECL_IS_NOVOPS (newdecl) |= DECL_IS_NOVOPS (olddecl);
         }
       
       /* Merge the storage class information.  */
       merge_weak (newdecl, olddecl);

       /* For functions, static overrides non-static.  */
       if (TREE_CODE (newdecl) == FUNCTION_DECL)
         {
           TREE_PUBLIC (newdecl) &= TREE_PUBLIC (olddecl);
           /* This is since we don't automatically
              copy the attributes of NEWDECL into OLDDECL.  */
           TREE_PUBLIC (olddecl) = TREE_PUBLIC (newdecl);
           /* If this clears `static', clear it in the identifier too.  */
           if (!TREE_PUBLIC (olddecl))
             TREE_PUBLIC (DECL_NAME (olddecl)) = 0;
         }
     }
   
   if (DECL_EXTERNAL (newdecl))
     {
       TREE_STATIC (newdecl) = TREE_STATIC (olddecl);
       DECL_EXTERNAL (newdecl) = DECL_EXTERNAL (olddecl);

       /* An extern decl does not override previous storage class.  */
       TREE_PUBLIC (newdecl) = TREE_PUBLIC (olddecl);
       if (!DECL_EXTERNAL (newdecl))
         {
           DECL_CONTEXT (newdecl) = DECL_CONTEXT (olddecl);
           DECL_COMMON (newdecl) = DECL_COMMON (olddecl);
         }
     }
   else
     {
       TREE_STATIC (olddecl) = TREE_STATIC (newdecl);
       TREE_PUBLIC (olddecl) = TREE_PUBLIC (newdecl);
     }
   
   if (TREE_CODE (newdecl) == FUNCTION_DECL) 
     {
       /* If we're redefining a function previously defined as extern
          inline, make sure we emit debug info for the inline before we
          throw it away, in case it was inlined into a function that hasn't
          been written out yet.  */
       if (new_is_definition && DECL_INITIAL (olddecl))
         {
           if (TREE_USED (olddecl)
               /* In unit-at-a-time mode we never inline re-defined extern
                  inline functions.  */
               && !flag_unit_at_a_time
               && cgraph_function_possibly_inlined_p (olddecl))
             (*debug_hooks->outlining_inline_function) (olddecl);

           /* The new defn must not be inline.  */
           DECL_INLINE (newdecl) = 0;
           DECL_UNINLINABLE (newdecl) = 1;
         }
       else
         {
           /* If either decl says `inline', this fn is inline,
              unless its definition was passed already.  */
           if (DECL_DECLARED_INLINE_P (newdecl)
               || DECL_DECLARED_INLINE_P (olddecl))
             DECL_DECLARED_INLINE_P (newdecl) = 1;

           DECL_UNINLINABLE (newdecl) = DECL_UNINLINABLE (olddecl)
             = (DECL_UNINLINABLE (newdecl) || DECL_UNINLINABLE (olddecl));
         }

       if (DECL_BUILT_IN (olddecl))
         {
           /* If redeclaring a builtin function, it stays built in.
              But it gets tagged as having been declared.  */
           DECL_BUILT_IN_CLASS (newdecl) = DECL_BUILT_IN_CLASS (olddecl);
           DECL_FUNCTION_CODE (newdecl) = DECL_FUNCTION_CODE (olddecl);
           C_DECL_DECLARED_BUILTIN (newdecl) = 1;
           if (new_is_prototype)
             C_DECL_BUILTIN_PROTOTYPE (newdecl) = 0;
           else
             C_DECL_BUILTIN_PROTOTYPE (newdecl)
               = C_DECL_BUILTIN_PROTOTYPE (olddecl);
         }

       /* Also preserve various other info from the definition.  */
       if (!new_is_definition)
         {
           DECL_RESULT (newdecl) = DECL_RESULT (olddecl);
           DECL_INITIAL (newdecl) = DECL_INITIAL (olddecl);
           DECL_STRUCT_FUNCTION (newdecl) = DECL_STRUCT_FUNCTION (olddecl);
           DECL_SAVED_TREE (newdecl) = DECL_SAVED_TREE (olddecl);
           DECL_ARGUMENTS (newdecl) = DECL_ARGUMENTS (olddecl);

           /* Set DECL_INLINE on the declaration if we've got a body
              from which to instantiate.  */
           if (DECL_INLINE (olddecl) && !DECL_UNINLINABLE (newdecl))
             {
               DECL_INLINE (newdecl) = 1;
               DECL_ABSTRACT_ORIGIN (newdecl)
                 = DECL_ABSTRACT_ORIGIN (olddecl);
             }
         }
       else
         {
           /* If a previous declaration said inline, mark the
              definition as inlinable.  */
           if (DECL_DECLARED_INLINE_P (newdecl)
               && !DECL_UNINLINABLE (newdecl))
             DECL_INLINE (newdecl) = 1;
         }
     }
   
   /* Copy most of the decl-specific fields of NEWDECL into OLDDECL.
     But preserve OLDDECL's DECL_UID and DECL_CONTEXT.  */
  {
    unsigned olddecl_uid = DECL_UID (olddecl);
    tree olddecl_context = DECL_CONTEXT (olddecl);
    
    memcpy ((char *) olddecl + sizeof (struct tree_common),
            (char *) newdecl + sizeof (struct tree_common),
            sizeof (struct tree_decl_common) - sizeof (struct tree_common));
    switch (TREE_CODE (olddecl))
      {
      case FIELD_DECL:
      case VAR_DECL:
      case PARM_DECL:
      case LABEL_DECL:
      case RESULT_DECL:
      case CONST_DECL:
      case TYPE_DECL:
      case FUNCTION_DECL:
        memcpy ((char *) olddecl + sizeof (struct tree_decl_common),
                (char *) newdecl + sizeof (struct tree_decl_common),
                tree_code_size (TREE_CODE (olddecl)) - sizeof (struct tree_decl_common));
        break;

      default:
        
        memcpy ((char *) olddecl + sizeof (struct tree_decl_common),
                (char *) newdecl + sizeof (struct tree_decl_common),
                sizeof (struct tree_decl_non_common) - sizeof (struct tree_decl_common));
      }
    DECL_UID (olddecl) = olddecl_uid;
    DECL_CONTEXT (olddecl) = olddecl_context;
  }

  /* If OLDDECL had its DECL_RTL instantiated, re-invoke make_decl_rtl
     so that encode_section_info has a chance to look at the new decl
     flags and attributes.  */
  if (DECL_RTL_SET_P (olddecl)
      && (TREE_CODE (olddecl) == FUNCTION_DECL
          || (TREE_CODE (olddecl) == VAR_DECL
              && TREE_STATIC (olddecl))))
    make_decl_rtl (olddecl);
}

/* Handle when a new declaration NEWDECL has the same name as an old
   one OLDDECL in the same binding contour.  Prints an error message
   if appropriate.

   If safely possible, alter OLDDECL to look like NEWDECL, and return
   true.  Otherwise, return false.  */

static bool
duplicate_decls (tree newdecl, tree olddecl)
{
  tree newtype = NULL, oldtype = NULL;

  if (!diagnose_mismatched_decls (newdecl, olddecl, &newtype, &oldtype))
    return false;

  merge_decls (newdecl, olddecl, newtype, oldtype);
  return true;
}

\f
/* Check whether decl-node NEW_DECL shadows an existing declaration.  */
static void
warn_if_shadowing (tree new_decl)
{
  struct c_binding *b;

  /* Shadow warnings wanted?  */
  if (!warn_shadow
      /* No shadow warnings for internally generated vars.  */
      || DECL_IS_BUILTIN (new_decl)
      /* No shadow warnings for vars made for inlining.  */
      || DECL_FROM_INLINE (new_decl))
    return;

  /* Is anything being shadowed?  Invisible decls do not count.  */
  for (b = I_SYMBOL_BINDING (DECL_NAME (new_decl)); b; b = b->shadowed)
    if (b->decl && b->decl != new_decl && !b->invisible)
      {
        tree old_decl = b->decl;

        if (old_decl == error_mark_node)
          {
            warning (OPT_Wshadow, "declaration of %q+D shadows previous "
                     "non-variable", new_decl);
            break;
          }
        else if (TREE_CODE (old_decl) == PARM_DECL)
          warning (OPT_Wshadow, "declaration of %q+D shadows a parameter",
                   new_decl);
        else if (DECL_FILE_SCOPE_P (old_decl))
          warning (OPT_Wshadow, "declaration of %q+D shadows a global "
                   "declaration", new_decl);
        else if (TREE_CODE (old_decl) == FUNCTION_DECL
                 && DECL_BUILT_IN (old_decl))
          {
            warning (OPT_Wshadow, "declaration of %q+D shadows "
                     "a built-in function", new_decl);
            break;
          }
        else
          warning (OPT_Wshadow, "declaration of %q+D shadows a previous local",
                   new_decl);

        warning (OPT_Wshadow, "%Jshadowed declaration is here", old_decl);

        break;
      }
}


/* Subroutine of pushdecl.

   X is a TYPE_DECL for a typedef statement.  Create a brand new
   ..._TYPE node (which will be just a variant of the existing
   ..._TYPE node with identical properties) and then install X
   as the TYPE_NAME of this brand new (duplicate) ..._TYPE node.

   The whole point here is to end up with a situation where each
   and every ..._TYPE node the compiler creates will be uniquely
   associated with AT MOST one node representing a typedef name.
   This way, even though the compiler substitutes corresponding
   ..._TYPE nodes for TYPE_DECL (i.e. "typedef name") nodes very
   early on, later parts of the compiler can always do the reverse
   translation and get back the corresponding typedef name.  For
   example, given:

        typedef struct S MY_TYPE;
        MY_TYPE object;

   Later parts of the compiler might only know that `object' was of
   type `struct S' if it were not for code just below.  With this
   code however, later parts of the compiler see something like:

        struct S' == struct S
        typedef struct S' MY_TYPE;
        struct S' object;

    And they can then deduce (from the node for type struct S') that
    the original object declaration was:

                MY_TYPE object;

    Being able to do this is important for proper support of protoize,
    and also for generating precise symbolic debugging information
    which takes full account of the programmer's (typedef) vocabulary.

    Obviously, we don't want to generate a duplicate ..._TYPE node if
    the TYPE_DECL node that we are now processing really represents a
    standard built-in type.

    Since all standard types are effectively declared at line zero
    in the source file, we can easily check to see if we are working
    on a standard type by checking the current value of lineno.  */

static void
clone_underlying_type (tree x)
{
  if (DECL_IS_BUILTIN (x))
    {
      if (TYPE_NAME (TREE_TYPE (x)) == 0)
        TYPE_NAME (TREE_TYPE (x)) = x;
    }
  else if (TREE_TYPE (x) != error_mark_node
           && DECL_ORIGINAL_TYPE (x) == NULL_TREE)
    {
      tree tt = TREE_TYPE (x);
      DECL_ORIGINAL_TYPE (x) = tt;
      tt = build_variant_type_copy (tt);
      TYPE_NAME (tt) = x;
      TREE_USED (tt) = TREE_USED (x);
      TREE_TYPE (x) = tt;
    }
}

/* Record a decl-node X as belonging to the current lexical scope.
   Check for errors (such as an incompatible declaration for the same
   name already seen in the same scope).

   Returns either X or an old decl for the same name.
   If an old decl is returned, it may have been smashed
   to agree with what X says.  */

tree
pushdecl (tree x)
{
  tree name = DECL_NAME (x);
  struct c_scope *scope = current_scope;
  struct c_binding *b;
  bool nested = false;

  /* Functions need the lang_decl data.  */
  if (TREE_CODE (x) == FUNCTION_DECL && !DECL_LANG_SPECIFIC (x))
    DECL_LANG_SPECIFIC (x) = GGC_CNEW (struct lang_decl);

  /* Must set DECL_CONTEXT for everything not at file scope or
     DECL_FILE_SCOPE_P won't work.  Local externs don't count
     unless they have initializers (which generate code).  */
  if (current_function_decl
      && ((TREE_CODE (x) != FUNCTION_DECL && TREE_CODE (x) != VAR_DECL)
          || DECL_INITIAL (x) || !DECL_EXTERNAL (x)))
    DECL_CONTEXT (x) = current_function_decl;

  /* If this is of variably modified type, prevent jumping into its
     scope.  */
  if ((TREE_CODE (x) == VAR_DECL || TREE_CODE (x) == TYPE_DECL)
      && variably_modified_type_p (TREE_TYPE (x), NULL_TREE))
    c_begin_vm_scope (scope->depth);

  /* Anonymous decls are just inserted in the scope.  */
  if (!name)
    {
      bind (name, x, scope, /*invisible=*/false, /*nested=*/false);
      return x;
    }

  /* First, see if there is another declaration with the same name in
     the current scope.  If there is, duplicate_decls may do all the
     work for us.  If duplicate_decls returns false, that indicates
     two incompatible decls in the same scope; we are to silently
     replace the old one (duplicate_decls has issued all appropriate
     diagnostics).  In particular, we should not consider possible
     duplicates in the external scope, or shadowing.  */
  b = I_SYMBOL_BINDING (name);
  if (b && B_IN_SCOPE (b, scope))
    {
      struct c_binding *b_ext, *b_use;
      tree type = TREE_TYPE (x);
      tree visdecl = b->decl;
      tree vistype = TREE_TYPE (visdecl);
      if (TREE_CODE (TREE_TYPE (x)) == ARRAY_TYPE
          && COMPLETE_TYPE_P (TREE_TYPE (x)))
        b->inner_comp = false;
      b_use = b;
      b_ext = b;
      /* If this is an external linkage declaration, we should check
         for compatibility with the type in the external scope before
         setting the type at this scope based on the visible
         information only.  */
      if (TREE_PUBLIC (x) && TREE_PUBLIC (visdecl))
        {
          while (b_ext && !B_IN_EXTERNAL_SCOPE (b_ext))
            b_ext = b_ext->shadowed;
          if (b_ext)
            {
              b_use = b_ext;
              if (b_use->type)
                TREE_TYPE (b_use->decl) = b_use->type;
            }
        }
      if (duplicate_decls (x, b_use->decl))
        {
          if (b_use != b)
            {
              /* Save the updated type in the external scope and
                 restore the proper type for this scope.  */
              tree thistype;
              if (comptypes (vistype, type))
                thistype = composite_type (vistype, type);
              else
                thistype = TREE_TYPE (b_use->decl);
              b_use->type = TREE_TYPE (b_use->decl);
              if (TREE_CODE (b_use->decl) == FUNCTION_DECL
                  && DECL_BUILT_IN (b_use->decl))
                thistype
                  = build_type_attribute_variant (thistype,
                                                  TYPE_ATTRIBUTES
                                                  (b_use->type));
              TREE_TYPE (b_use->decl) = thistype;
            }
          return b_use->decl;
        }
      else
        goto skip_external_and_shadow_checks;
    }

  /* All declarations with external linkage, and all external
     references, go in the external scope, no matter what scope is
     current.  However, the binding in that scope is ignored for
     purposes of normal name lookup.  A separate binding structure is
     created in the requested scope; this governs the normal
     visibility of the symbol.

     The binding in the externals scope is used exclusively for
     detecting duplicate declarations of the same object, no matter
     what scope they are in; this is what we do here.  (C99 6.2.7p2:
     All declarations that refer to the same object or function shall
     have compatible type; otherwise, the behavior is undefined.)  */
  if (DECL_EXTERNAL (x) || scope == file_scope)
    {
      tree type = TREE_TYPE (x);
      tree vistype = 0;
      tree visdecl = 0;
      bool type_saved = false;
      if (b && !B_IN_EXTERNAL_SCOPE (b)
          && (TREE_CODE (b->decl) == FUNCTION_DECL
              || TREE_CODE (b->decl) == VAR_DECL)
          && DECL_FILE_SCOPE_P (b->decl))
        {
          visdecl = b->decl;
          vistype = TREE_TYPE (visdecl);
        }
      if (scope != file_scope
          && !DECL_IN_SYSTEM_HEADER (x))
        warning (OPT_Wnested_externs, "nested extern declaration of %qD", x);

      while (b && !B_IN_EXTERNAL_SCOPE (b))
        {
          /* If this decl might be modified, save its type.  This is
             done here rather than when the decl is first bound
             because the type may change after first binding, through
             being completed or through attributes being added.  If we
             encounter multiple such decls, only the first should have
             its type saved; the others will already have had their
             proper types saved and the types will not have changed as
             their scopes will not have been re-entered.  */
          if (DECL_P (b->decl) && DECL_FILE_SCOPE_P (b->decl) && !type_saved)
            {
              b->type = TREE_TYPE (b->decl);
              type_saved = true;
            }
          if (B_IN_FILE_SCOPE (b)
              && TREE_CODE (b->decl) == VAR_DECL
              && TREE_STATIC (b->decl)
              && TREE_CODE (TREE_TYPE (b->decl)) == ARRAY_TYPE
              && !TYPE_DOMAIN (TREE_TYPE (b->decl))
              && TREE_CODE (type) == ARRAY_TYPE
              && TYPE_DOMAIN (type)
              && TYPE_MAX_VALUE (TYPE_DOMAIN (type))
              && !integer_zerop (TYPE_MAX_VALUE (TYPE_DOMAIN (type))))
            {
              /* Array type completed in inner scope, which should be
                 diagnosed if the completion does not have size 1 and
                 it does not get completed in the file scope.  */
              b->inner_comp = true;
            }
          b = b->shadowed;
        }

      /* If a matching external declaration has been found, set its
         type to the composite of all the types of that declaration.
         After the consistency checks, it will be reset to the
         composite of the visible types only.  */
      if (b && (TREE_PUBLIC (x) || same_translation_unit_p (x, b->decl))
          && b->type)
        TREE_TYPE (b->decl) = b->type;

      /* The point of the same_translation_unit_p check here is,
         we want to detect a duplicate decl for a construct like
         foo() { extern bar(); } ... static bar();  but not if
         they are in different translation units.  In any case,
         the static does not go in the externals scope.  */
      if (b
          && (TREE_PUBLIC (x) || same_translation_unit_p (x, b->decl))
          && duplicate_decls (x, b->decl))
        {
          tree thistype;
          if (vistype)
            {
              if (comptypes (vistype, type))
                thistype = composite_type (vistype, type);
              else
                thistype = TREE_TYPE (b->decl);
            }
          else
            thistype = type;
          b->type = TREE_TYPE (b->decl);
          if (TREE_CODE (b->decl) == FUNCTION_DECL && DECL_BUILT_IN (b->decl))
            thistype
              = build_type_attribute_variant (thistype,
                                              TYPE_ATTRIBUTES (b->type));
          TREE_TYPE (b->decl) = thistype;
          bind (name, b->decl, scope, /*invisible=*/false, /*nested=*/true);
          return b->decl;
        }
      else if (TREE_PUBLIC (x))
        {
          if (visdecl && !b && duplicate_decls (x, visdecl))
            {
              /* An external declaration at block scope referring to a
                 visible entity with internal linkage.  The composite
                 type will already be correct for this scope, so we
                 just need to fall through to make the declaration in
                 this scope.  */
              nested = true;
              x = visdecl;
            }
          else
            {
              bind (name, x, external_scope, /*invisible=*/true,
                    /*nested=*/false);
              nested = true;
            }
        }
    }

  if (TREE_CODE (x) != PARM_DECL)
    warn_if_shadowing (x);

 skip_external_and_shadow_checks:
  if (TREE_CODE (x) == TYPE_DECL)
    clone_underlying_type (x);

  bind (name, x, scope, /*invisible=*/false, nested);

  /* If x's type is incomplete because it's based on a
     structure or union which has not yet been fully declared,
     attach it to that structure or union type, so we can go
     back and complete the variable declaration later, if the
     structure or union gets fully declared.

     If the input is erroneous, we can have error_mark in the type
     slot (e.g. "f(void a, ...)") - that doesn't count as an
     incomplete type.  */
  if (TREE_TYPE (x) != error_mark_node
      && !COMPLETE_TYPE_P (TREE_TYPE (x)))
    {
      tree element = TREE_TYPE (x);

      while (TREE_CODE (element) == ARRAY_TYPE)
        element = TREE_TYPE (element);
      element = TYPE_MAIN_VARIANT (element);

      if ((TREE_CODE (element) == RECORD_TYPE
           || TREE_CODE (element) == UNION_TYPE)
          && (TREE_CODE (x) != TYPE_DECL
              || TREE_CODE (TREE_TYPE (x)) == ARRAY_TYPE)
          && !COMPLETE_TYPE_P (element))
        C_TYPE_INCOMPLETE_VARS (element)
          = tree_cons (NULL_TREE, x, C_TYPE_INCOMPLETE_VARS (element));
    }
  return x;
}

/* Record X as belonging to file scope.
   This is used only internally by the Objective-C front end,
   and is limited to its needs.  duplicate_decls is not called;
   if there is any preexisting decl for this identifier, it is an ICE.  */

tree
pushdecl_top_level (tree x)
{
  tree name;
  bool nested = false;
  gcc_assert (TREE_CODE (x) == VAR_DECL || TREE_CODE (x) == CONST_DECL);

  name = DECL_NAME (x);

 gcc_assert (TREE_CODE (x) == CONST_DECL || !I_SYMBOL_BINDING (name));

  if (TREE_PUBLIC (x))
    {
      bind (name, x, external_scope, /*invisible=*/true, /*nested=*/false);
      nested = true;
    }
  if (file_scope)
    bind (name, x, file_scope, /*invisible=*/false, nested);

  return x;
}
\f
static void
implicit_decl_warning (tree id, tree olddecl)
{
  void (*diag) (const char *, ...) ATTRIBUTE_GCC_CDIAG(1,2);
  switch (mesg_implicit_function_declaration)
    {
    case 0: return;
    case 1: diag = warning0; break;
    case 2: diag = error;   break;
    default: gcc_unreachable ();
    }

  diag (G_("implicit declaration of function %qE"), id);
  if (olddecl)
    locate_old_decl (olddecl, diag);
}

/* Generate an implicit declaration for identifier FUNCTIONID as a
   function of type int ().  */

tree
implicitly_declare (tree functionid)
{
  struct c_binding *b;
  tree decl = 0;
  tree asmspec_tree;

  for (b = I_SYMBOL_BINDING (functionid); b; b = b->shadowed)
    {
      if (B_IN_SCOPE (b, external_scope))
        {
          decl = b->decl;
          break;
        }
    }

  if (decl)
    {
      if (decl == error_mark_node)
        return decl;

      /* FIXME: Objective-C has weird not-really-builtin functions
         which are supposed to be visible automatically.  They wind up
         in the external scope because they're pushed before the file
         scope gets created.  Catch this here and rebind them into the
         file scope.  */
      if (!DECL_BUILT_IN (decl) && DECL_IS_BUILTIN (decl))
        {
          bind (functionid, decl, file_scope,
                /*invisible=*/false, /*nested=*/true);
          return decl;
        }
      else
        {
          tree newtype = default_function_type;
          if (b->type)
            TREE_TYPE (decl) = b->type;
          /* Implicit declaration of a function already declared
             (somehow) in a different scope, or as a built-in.
             If this is the first time this has happened, warn;
             then recycle the old declaration but with the new type.  */
          if (!C_DECL_IMPLICIT (decl))
            {
              implicit_decl_warning (functionid, decl);
              C_DECL_IMPLICIT (decl) = 1;
            }
          if (DECL_BUILT_IN (decl))
            {
              newtype = build_type_attribute_variant (newtype,
                                                      TYPE_ATTRIBUTES
                                                      (TREE_TYPE (decl)));
              if (!comptypes (newtype, TREE_TYPE (decl)))
                {
                  warning (0, "incompatible implicit declaration of built-in"
                           " function %qD", decl);
                  newtype = TREE_TYPE (decl);
                }
            }
          else
            {
              if (!comptypes (newtype, TREE_TYPE (decl)))
                {
                  error ("incompatible implicit declaration of function %qD",
                         decl);
                  locate_old_decl (decl, error);
                }
            }
          b->type = TREE_TYPE (decl);
          TREE_TYPE (decl) = newtype;
          bind (functionid, decl, current_scope,
                /*invisible=*/false, /*nested=*/true);
          return decl;
        }
    }

  /* Not seen before.  */
  decl = build_decl (FUNCTION_DECL, functionid, default_function_type);
  DECL_EXTERNAL (decl) = 1;
  TREE_PUBLIC (decl) = 1;
  C_DECL_IMPLICIT (decl) = 1;
  implicit_decl_warning (functionid, 0);
  asmspec_tree = maybe_apply_renaming_pragma (decl, /*asmname=*/NULL);
  if (asmspec_tree)
    set_user_assembler_name (decl, TREE_STRING_POINTER (asmspec_tree));

  /* C89 says implicit declarations are in the innermost block.
     So we record the decl in the standard fashion.  */
  decl = pushdecl (decl);

  /* No need to call objc_check_decl here - it's a function type.  */
  rest_of_decl_compilation (decl, 0, 0);

  /* Write a record describing this implicit function declaration
     to the prototypes file (if requested).  */
  gen_aux_info_record (decl, 0, 1, 0);

  /* Possibly apply some default attributes to this implicit declaration.  */
  decl_attributes (&decl, NULL_TREE, 0);

  return decl;
}

/* Issue an error message for a reference to an undeclared variable
   ID, including a reference to a builtin outside of function-call
   context.  Establish a binding of the identifier to error_mark_node
   in an appropriate scope, which will suppress further errors for the
   same identifier.  The error message should be given location LOC.  */
void
undeclared_variable (tree id, location_t loc)
{
  static bool already = false;
  struct c_scope *scope;

  if (current_function_decl == 0)
    {
      error ("%H%qE undeclared here (not in a function)", &loc, id);
      scope = current_scope;
    }
  else
    {
      error ("%H%qE undeclared (first use in this function)", &loc, id);

      if (!already)
        {
          error ("%H(Each undeclared identifier is reported only once", &loc);
          error ("%Hfor each function it appears in.)", &loc);
          already = true;
        }

      /* If we are parsing old-style parameter decls, current_function_decl
         will be nonnull but current_function_scope will be null.  */
      scope = current_function_scope ? current_function_scope : current_scope;
    }
  bind (id, error_mark_node, scope, /*invisible=*/false, /*nested=*/false);
}
\f
/* Subroutine of lookup_label, declare_label, define_label: construct a
   LABEL_DECL with all the proper frills.  */

static tree
make_label (tree name, location_t location)
{
  tree label = build_decl (LABEL_DECL, name, void_type_node);

  DECL_CONTEXT (label) = current_function_decl;
  DECL_MODE (label) = VOIDmode;
  DECL_SOURCE_LOCATION (label) = location;

  return label;
}

/* Get the LABEL_DECL corresponding to identifier NAME as a label.
   Create one if none exists so far for the current function.
   This is called when a label is used in a goto expression or
   has its address taken.  */

tree
lookup_label (tree name)
{
  tree label;

  if (current_function_decl == 0)
    {
      error ("label %qE referenced outside of any function", name);
      return 0;
    }

  /* Use a label already defined or ref'd with this name, but not if
     it is inherited from a containing function and wasn't declared
     using __label__.  */
  label = I_LABEL_DECL (name);
  if (label && (DECL_CONTEXT (label) == current_function_decl
                || C_DECLARED_LABEL_FLAG (label)))
    {
      /* If the label has only been declared, update its apparent
         location to point here, for better diagnostics if it
         turns out not to have been defined.  */
      if (!TREE_USED (label))
        DECL_SOURCE_LOCATION (label) = input_location;
      return label;
    }

  /* No label binding for that identifier; make one.  */
  label = make_label (name, input_location);

  /* Ordinary labels go in the current function scope.  */
  bind (name, label, current_function_scope,
        /*invisible=*/false, /*nested=*/false);
  return label;
}

/* Make a label named NAME in the current function, shadowing silently
   any that may be inherited from containing functions or containing
   scopes.  This is called for __label__ declarations.  */

tree
declare_label (tree name)
{
  struct c_binding *b = I_LABEL_BINDING (name);
  tree label;

  /* Check to make sure that the label hasn't already been declared
     at this scope */
  if (b && B_IN_CURRENT_SCOPE (b))
    {
      error ("duplicate label declaration %qE", name);
      locate_old_decl (b->decl, error);

      /* Just use the previous declaration.  */
      return b->decl;
    }

  label = make_label (name, input_location);
  C_DECLARED_LABEL_FLAG (label) = 1;

  /* Declared labels go in the current scope.  */
  bind (name, label, current_scope,
        /*invisible=*/false, /*nested=*/false);
  return label;
}

/* Define a label, specifying the location in the source file.
   Return the LABEL_DECL node for the label, if the definition is valid.
   Otherwise return 0.  */

tree
define_label (location_t location, tree name)
{
  /* Find any preexisting label with this name.  It is an error
     if that label has already been defined in this function, or
     if there is a containing function with a declared label with
     the same name.  */
  tree label = I_LABEL_DECL (name);
  struct c_label_list *nlist_se, *nlist_vm;

  if (label
      && ((DECL_CONTEXT (label) == current_function_decl
           && DECL_INITIAL (label) != 0)
          || (DECL_CONTEXT (label) != current_function_decl
              && C_DECLARED_LABEL_FLAG (label))))
    {
      error ("%Hduplicate label %qD", &location, label);
      locate_old_decl (label, error);
      return 0;
    }
  else if (label && DECL_CONTEXT (label) == current_function_decl)
    {
      /* The label has been used or declared already in this function,
         but not defined.  Update its location to point to this
         definition.  */
      if (C_DECL_UNDEFINABLE_STMT_EXPR (label))
        error ("%Jjump into statement expression", label);
      if (C_DECL_UNDEFINABLE_VM (label))
        error ("%Jjump into scope of identifier with variably modified type",
               label);
      DECL_SOURCE_LOCATION (label) = location;
    }
  else
    {
      /* No label binding for that identifier; make one.  */
      label = make_label (name, location);

      /* Ordinary labels go in the current function scope.  */
      bind (name, label, current_function_scope,
            /*invisible=*/false, /*nested=*/false);
    }

  if (!in_system_header && lookup_name (name))
    warning (OPT_Wtraditional, "%Htraditional C lacks a separate namespace "
             "for labels, identifier %qE conflicts", &location, name);

  nlist_se = XOBNEW (&parser_obstack, struct c_label_list);
  nlist_se->next = label_context_stack_se->labels_def;
  nlist_se->label = label;
  label_context_stack_se->labels_def = nlist_se;

  nlist_vm = XOBNEW (&parser_obstack, struct c_label_list);
  nlist_vm->next = label_context_stack_vm->labels_def;
  nlist_vm->label = label;
  label_context_stack_vm->labels_def = nlist_vm;

  /* Mark label as having been defined.  */
  DECL_INITIAL (label) = error_mark_node;
  return label;
}
\f
/* Given NAME, an IDENTIFIER_NODE,
   return the structure (or union or enum) definition for that name.
   If THISLEVEL_ONLY is nonzero, searches only the current_scope.
   CODE says which kind of type the caller wants;
   it is RECORD_TYPE or UNION_TYPE or ENUMERAL_TYPE.
   If the wrong kind of type is found, an error is reported.  */

static tree
lookup_tag (enum tree_code code, tree name, int thislevel_only)
{
  struct c_binding *b = I_TAG_BINDING (name);
  int thislevel = 0;

  if (!b || !b->decl)
    return 0;

  /* We only care about whether it's in this level if
     thislevel_only was set or it might be a type clash.  */
  if (thislevel_only || TREE_CODE (b->decl) != code)
    {
      /* For our purposes, a tag in the external scope is the same as
         a tag in the file scope.  (Primarily relevant to Objective-C
         and its builtin structure tags, which get pushed before the
         file scope is created.)  */
      if (B_IN_CURRENT_SCOPE (b)
          || (current_scope == file_scope && B_IN_EXTERNAL_SCOPE (b)))
        thislevel = 1;
    }

  if (thislevel_only && !thislevel)
    return 0;

  if (TREE_CODE (b->decl) != code)
    {
      /* Definition isn't the kind we were looking for.  */
      pending_invalid_xref = name;
      pending_invalid_xref_location = input_location;

      /* If in the same binding level as a declaration as a tag
         of a different type, this must not be allowed to
         shadow that tag, so give the error immediately.
         (For example, "struct foo; union foo;" is invalid.)  */
      if (thislevel)
        pending_xref_error ();
    }
  return b->decl;
}

/* Print an error message now
   for a recent invalid struct, union or enum cross reference.
   We don't print them immediately because they are not invalid
   when used in the `struct foo;' construct for shadowing.  */

void
pending_xref_error (void)
{
  if (pending_invalid_xref != 0)
    error ("%H%qE defined as wrong kind of tag",
           &pending_invalid_xref_location, pending_invalid_xref);
  pending_invalid_xref = 0;
}

\f
/* Look up NAME in the current scope and its superiors
   in the namespace of variables, functions and typedefs.
   Return a ..._DECL node of some kind representing its definition,
   or return 0 if it is undefined.  */

tree
lookup_name (tree name)
{
  struct c_binding *b = I_SYMBOL_BINDING (name);
  if (b && !b->invisible)
    return b->decl;
  return 0;
}

/* Similar to `lookup_name' but look only at the indicated scope.  */

static tree
lookup_name_in_scope (tree name, struct c_scope *scope)
{
  struct c_binding *b;

  for (b = I_SYMBOL_BINDING (name); b; b = b->shadowed)
    if (B_IN_SCOPE (b, scope))
      return b->decl;
  return 0;
}
\f
/* Create the predefined scalar types of C,
   and some nodes representing standard constants (0, 1, (void *) 0).
   Initialize the global scope.
   Make definitions for built-in primitive functions.  */

void
c_init_decl_processing (void)
{
  location_t save_loc = input_location;

  /* Initialize reserved words for parser.  */
  c_parse_init ();

  current_function_decl = 0;

  gcc_obstack_init (&parser_obstack);

  /* Make the externals scope.  */
  push_scope ();
  external_scope = current_scope;

  /* Declarations from c_common_nodes_and_builtins must not be associated
     with this input file, lest we get differences between using and not
     using preprocessed headers.  */
#ifdef USE_MAPPED_LOCATION
  input_location = BUILTINS_LOCATION;
#else
  input_location.file = "<built-in>";
  input_location.line = 0;
#endif

  build_common_tree_nodes (flag_signed_char, false);

  c_common_nodes_and_builtins ();

  /* In C, comparisons and TRUTH_* expressions have type int.  */
  truthvalue_type_node = integer_type_node;
  truthvalue_true_node = integer_one_node;
  truthvalue_false_node = integer_zero_node;

  /* Even in C99, which has a real boolean type.  */
  pushdecl (build_decl (TYPE_DECL, get_identifier ("_Bool"),
                        boolean_type_node));

  input_location = save_loc;

  pedantic_lvalues = true;

  make_fname_decl = c_make_fname_decl;
  start_fname_decls ();
}

/* Create the VAR_DECL for __FUNCTION__ etc. ID is the name to give the
   decl, NAME is the initialization string and TYPE_DEP indicates whether
   NAME depended on the type of the function.  As we don't yet implement
   delayed emission of static data, we mark the decl as emitted
   so it is not placed in the output.  Anything using it must therefore pull
   out the STRING_CST initializer directly.  FIXME.  */

static tree
c_make_fname_decl (tree id, int type_dep)
{
  const char *name = fname_as_string (type_dep);
  tree decl, type, init;
  size_t length = strlen (name);

  type = build_array_type (char_type_node,
                           build_index_type (size_int (length)));
  type = c_build_qualified_type (type, TYPE_QUAL_CONST);

  decl = build_decl (VAR_DECL, id, type);

  TREE_STATIC (decl) = 1;
  TREE_READONLY (decl) = 1;
  DECL_ARTIFICIAL (decl) = 1;

  init = build_string (length + 1, name);
  free ((char *) name);
  TREE_TYPE (init) = type;
  DECL_INITIAL (decl) = init;

  TREE_USED (decl) = 1;

  if (current_function_decl)
    {
      DECL_CONTEXT (decl) = current_function_decl;
      bind (id, decl, current_function_scope,
            /*invisible=*/false, /*nested=*/false);
    }

  finish_decl (decl, init, NULL_TREE);

  return decl;
}

/* Return a definition for a builtin function named NAME and whose data type
   is TYPE.  TYPE should be a function type with argument types.
   FUNCTION_CODE tells later passes how to compile calls to this function.
   See tree.h for its possible values.

   If LIBRARY_NAME is nonzero, use that for DECL_ASSEMBLER_NAME,
   the name to be called if we can't opencode the function.  If
   ATTRS is nonzero, use that for the function's attribute list.  */

tree
builtin_function (const char *name, tree type, int function_code,
                  enum built_in_class cl, const char *library_name,
                  tree attrs)
{
  tree id = get_identifier (name);
  tree decl = build_decl (FUNCTION_DECL, id, type);
  TREE_PUBLIC (decl) = 1;
  DECL_EXTERNAL (decl) = 1;
  DECL_LANG_SPECIFIC (decl) = GGC_CNEW (struct lang_decl);
  DECL_BUILT_IN_CLASS (decl) = cl;
  DECL_FUNCTION_CODE (decl) = function_code;
  C_DECL_BUILTIN_PROTOTYPE (decl) = (TYPE_ARG_TYPES (type) != 0);
  if (library_name)
    SET_DECL_ASSEMBLER_NAME (decl, get_identifier (library_name));

  /* Should never be called on a symbol with a preexisting meaning.  */
  gcc_assert (!I_SYMBOL_BINDING (id));

  bind (id, decl, external_scope, /*invisible=*/true, /*nested=*/false);

  /* Builtins in the implementation namespace are made visible without
     needing to be explicitly declared.  See push_file_scope.  */
  if (name[0] == '_' && (name[1] == '_' || ISUPPER (name[1])))
    {
      TREE_CHAIN (decl) = visible_builtins;
      visible_builtins = decl;
    }

  /* Possibly apply some default attributes to this built-in function.  */
  if (attrs)
    decl_attributes (&decl, attrs, ATTR_FLAG_BUILT_IN);
  else
    decl_attributes (&decl, NULL_TREE, 0);

  return decl;
}
\f
/* Called when a declaration is seen that contains no names to declare.
   If its type is a reference to a structure, union or enum inherited
   from a containing scope, shadow that tag name for the current scope
   with a forward reference.
   If its type defines a new named structure or union
   or defines an enum, it is valid but we need not do anything here.
   Otherwise, it is an error.  */

void
shadow_tag (const struct c_declspecs *declspecs)
{
  shadow_tag_warned (declspecs, 0);
}

/* WARNED is 1 if we have done a pedwarn, 2 if we have done a warning,
   but no pedwarn.  */
void
shadow_tag_warned (const struct c_declspecs *declspecs, int warned)
{
  bool found_tag = false;

  if (declspecs->type && !declspecs->default_int_p && !declspecs->typedef_p)
    {
      tree value = declspecs->type;
      enum tree_code code = TREE_CODE (value);

      if (code == RECORD_TYPE || code == UNION_TYPE || code == ENUMERAL_TYPE)
        /* Used to test also that TYPE_SIZE (value) != 0.
           That caused warning for `struct foo;' at top level in the file.  */
        {
          tree name = TYPE_NAME (value);
          tree t;

          found_tag = true;

          if (name == 0)
            {
              if (warned != 1 && code != ENUMERAL_TYPE)
                /* Empty unnamed enum OK */
                {
                  pedwarn ("unnamed struct/union that defines no instances");
                  warned = 1;
                }
            }
          else if (!declspecs->tag_defined_p
                   && declspecs->storage_class != csc_none)
            {
              if (warned != 1)
                pedwarn ("empty declaration with storage class specifier "
                         "does not redeclare tag");
              warned = 1;
              pending_xref_error ();
            }
          else if (!declspecs->tag_defined_p
                   && (declspecs->const_p
                       || declspecs->volatile_p
                       || declspecs->restrict_p))
            {
              if (warned != 1)
                pedwarn ("empty declaration with type qualifier "
                         "does not redeclare tag");
              warned = 1;
              pending_xref_error ();
            }
          else
            {
              pending_invalid_xref = 0;
              t = lookup_tag (code, name, 1);

              if (t == 0)
                {
                  t = make_node (code);
                  pushtag (name, t);
                }
            }
        }
      else
        {
          if (warned != 1 && !in_system_header)
            {
              pedwarn ("useless type name in empty declaration");
              warned = 1;
            }
        }
    }
  else if (warned != 1 && !in_system_header && declspecs->typedef_p)
    {
      pedwarn ("useless type name in empty declaration");
      warned = 1;
    }

  pending_invalid_xref = 0;

  if (declspecs->inline_p)
    {
      error ("%<inline%> in empty declaration");
      warned = 1;
    }

  if (current_scope == file_scope && declspecs->storage_class == csc_auto)
    {
      error ("%<auto%> in file-scope empty declaration");
      warned = 1;
    }

  if (current_scope == file_scope && declspecs->storage_class == csc_register)
    {
      error ("%<register%> in file-scope empty declaration");
      warned = 1;
    }

  if (!warned && !in_system_header && declspecs->storage_class != csc_none)
    {
      warning (0, "useless storage class specifier in empty declaration");
      warned = 2;
    }

  if (!warned && !in_system_header && declspecs->thread_p)
    {
      warning (0, "useless %<__thread%> in empty declaration");
      warned = 2;
    }

  if (!warned && !in_system_header && (declspecs->const_p
                                       || declspecs->volatile_p
                                       || declspecs->restrict_p))
    {
      warning (0, "useless type qualifier in empty declaration");
      warned = 2;
    }

  if (warned != 1)
    {
      if (!found_tag)
        pedwarn ("empty declaration");
    }
}
\f

/* Return the qualifiers from SPECS as a bitwise OR of TYPE_QUAL_*
   bits.  SPECS represents declaration specifiers that the grammar
   only permits to contain type qualifiers and attributes.  */

int
quals_from_declspecs (const struct c_declspecs *specs)
{
  int quals = ((specs->const_p ? TYPE_QUAL_CONST : 0)
               | (specs->volatile_p ? TYPE_QUAL_VOLATILE : 0)
               | (specs->restrict_p ? TYPE_QUAL_RESTRICT : 0));
  gcc_assert (!specs->type
              && !specs->decl_attr
              && specs->typespec_word == cts_none
              && specs->storage_class == csc_none
              && !specs->typedef_p
              && !specs->explicit_signed_p
              && !specs->deprecated_p
              && !specs->long_p
              && !specs->long_long_p
              && !specs->short_p
              && !specs->signed_p
              && !specs->unsigned_p
              && !specs->complex_p
              && !specs->inline_p
              && !specs->thread_p);
  return quals;
}

/* Construct an array declarator.  EXPR is the expression inside [], or
   NULL_TREE.  QUALS are the type qualifiers inside the [] (to be applied
   to the pointer to which a parameter array is converted).  STATIC_P is
   true if "static" is inside the [], false otherwise.  VLA_UNSPEC_P
   is true if the array is [*], a VLA of unspecified length which is
   nevertheless a complete type (not currently implemented by GCC),
   false otherwise.  The field for the contained declarator is left to be
   filled in by set_array_declarator_inner.  */

struct c_declarator *
build_array_declarator (tree expr, struct c_declspecs *quals, bool static_p,
                        bool vla_unspec_p)
{
  struct c_declarator *declarator = XOBNEW (&parser_obstack,
                                            struct c_declarator);
  declarator->kind = cdk_array;
  declarator->declarator = 0;
  declarator->u.array.dimen = expr;
  if (quals)
    {
      declarator->u.array.attrs = quals->attrs;
      declarator->u.array.quals = quals_from_declspecs (quals);
    }
  else
    {
      declarator->u.array.attrs = NULL_TREE;
      declarator->u.array.quals = 0;
    }
  declarator->u.array.static_p = static_p;
  declarator->u.array.vla_unspec_p = vla_unspec_p;
  if (pedantic && !flag_isoc99)
    {
      if (static_p || quals != NULL)
        pedwarn ("ISO C90 does not support %<static%> or type "
                 "qualifiers in parameter array declarators");
      if (vla_unspec_p)
        pedwarn ("ISO C90 does not support %<[*]%> array declarators");
    }
  if (vla_unspec_p)
    warning (0, "GCC does not yet properly implement %<[*]%> array declarators");
  return declarator;
}

/* Set the contained declarator of an array declarator.  DECL is the
   declarator, as constructed by build_array_declarator; INNER is what
   appears on the left of the [].  ABSTRACT_P is true if it is an
   abstract declarator, false otherwise; this is used to reject static
   and type qualifiers in abstract declarators, where they are not in
   the C99 grammar (subject to possible change in DR#289).  */

struct c_declarator *
set_array_declarator_inner (struct c_declarator *decl,
                            struct c_declarator *inner, bool abstract_p)
{
  decl->declarator = inner;
  if (abstract_p && (decl->u.array.quals != TYPE_UNQUALIFIED
                     || decl->u.array.attrs != NULL_TREE
                     || decl->u.array.static_p))
    error ("static or type qualifiers in abstract declarator");
  return decl;
}
\f
/* Decode a "typename", such as "int **", returning a ..._TYPE node.  */

tree
groktypename (struct c_type_name *type_name)
{
  tree type;
  tree attrs = type_name->specs->attrs;

  type_name->specs->attrs = NULL_TREE;

  type = grokdeclarator (type_name->declarator, type_name->specs, TYPENAME,
                         false, NULL);

  /* Apply attributes.  */
  decl_attributes (&type, attrs, 0);

  return type;
}

/* Decode a declarator in an ordinary declaration or data definition.
   This is called as soon as the type information and variable name
   have been parsed, before parsing the initializer if any.
   Here we create the ..._DECL node, fill in its type,
   and put it on the list of decls for the current context.
   The ..._DECL node is returned as the value.

   Exception: for arrays where the length is not specified,
   the type is left null, to be filled in by `finish_decl'.

   Function definitions do not come here; they go to start_function
   instead.  However, external and forward declarations of functions
   do go through here.  Structure field declarations are done by
   grokfield and not through here.  */

tree
start_decl (struct c_declarator *declarator, struct c_declspecs *declspecs,
            bool initialized, tree attributes)
{
  tree decl;
  tree tem;

  /* An object declared as __attribute__((deprecated)) suppresses
     warnings of uses of other deprecated items.  */
  if (lookup_attribute ("deprecated", attributes))
    deprecated_state = DEPRECATED_SUPPRESS;

  decl = grokdeclarator (declarator, declspecs,
                         NORMAL, initialized, NULL);
  if (!decl)
    return 0;

  deprecated_state = DEPRECATED_NORMAL;

  if (warn_main > 0 && TREE_CODE (decl) != FUNCTION_DECL
      && MAIN_NAME_P (DECL_NAME (decl)))
    warning (OPT_Wmain, "%q+D is usually a function", decl);

  if (initialized)
    /* Is it valid for this decl to have an initializer at all?
       If not, set INITIALIZED to zero, which will indirectly
       tell 'finish_decl' to ignore the initializer once it is parsed.  */
    switch (TREE_CODE (decl))
      {
      case TYPE_DECL:
        error ("typedef %qD is initialized (use __typeof__ instead)", decl);
        initialized = 0;
        break;

      case FUNCTION_DECL:
        error ("function %qD is initialized like a variable", decl);
        initialized = 0;
        break;

      case PARM_DECL:
        /* DECL_INITIAL in a PARM_DECL is really DECL_ARG_TYPE.  */
        error ("parameter %qD is initialized", decl);
        initialized = 0;
        break;

      default:
        /* Don't allow initializations for incomplete types except for
           arrays which might be completed by the initialization.  */

        /* This can happen if the array size is an undefined macro.
           We already gave a warning, so we don't need another one.  */
        if (TREE_TYPE (decl) == error_mark_node)
          initialized = 0;
        else if (COMPLETE_TYPE_P (TREE_TYPE (decl)))
          {
            /* A complete type is ok if size is fixed.  */

            if (TREE_CODE (TYPE_SIZE (TREE_TYPE (decl))) != INTEGER_CST
                || C_DECL_VARIABLE_SIZE (decl))
              {
                error ("variable-sized object may not be initialized");
                initialized = 0;
              }
          }
        else if (TREE_CODE (TREE_TYPE (decl)) != ARRAY_TYPE)
          {
            error ("variable %qD has initializer but incomplete type", decl);
            initialized = 0;
          }
        else if (C_DECL_VARIABLE_SIZE (decl))
          {
            /* Although C99 is unclear about whether incomplete arrays
               of VLAs themselves count as VLAs, it does not make
               sense to permit them to be initialized given that
               ordinary VLAs may not be initialized.  */
            error ("variable-sized object may not be initialized");
            initialized = 0;
          }
      }

  if (initialized)
    {
      if (current_scope == file_scope)
        TREE_STATIC (decl) = 1;

      /* Tell 'pushdecl' this is an initialized decl
         even though we don't yet have the initializer expression.
         Also tell 'finish_decl' it may store the real initializer.  */
      DECL_INITIAL (decl) = error_mark_node;
    }

  /* If this is a function declaration, write a record describing it to the
     prototypes file (if requested).  */

  if (TREE_CODE (decl) == FUNCTION_DECL)
    gen_aux_info_record (decl, 0, 0, TYPE_ARG_TYPES (TREE_TYPE (decl)) != 0);

  /* ANSI specifies that a tentative definition which is not merged with
     a non-tentative definition behaves exactly like a definition with an
     initializer equal to zero.  (Section 3.7.2)

     -fno-common gives strict ANSI behavior, though this tends to break
     a large body of code that grew up without this rule.

     Thread-local variables are never common, since there's no entrenched
     body of code to break, and it allows more efficient variable references
     in the presence of dynamic linking.  */

  if (TREE_CODE (decl) == VAR_DECL
      && !initialized
      && TREE_PUBLIC (decl)
      && !DECL_THREAD_LOCAL_P (decl)
      && !flag_no_common)
    DECL_COMMON (decl) = 1;

  /* Set attributes here so if duplicate decl, will have proper attributes.  */
  decl_attributes (&decl, attributes, 0);

  if (TREE_CODE (decl) == FUNCTION_DECL
      && targetm.calls.promote_prototypes (TREE_TYPE (decl)))
    {
      struct c_declarator *ce = declarator;

      if (ce->kind == cdk_pointer)
        ce = declarator->declarator;
      if (ce->kind == cdk_function)
        {
          tree args = ce->u.arg_info->parms;
          for (; args; args = TREE_CHAIN (args))
            {
              tree type = TREE_TYPE (args);
              if (type && INTEGRAL_TYPE_P (type)
                  && TYPE_PRECISION (type) < TYPE_PRECISION (integer_type_node))
                DECL_ARG_TYPE (args) = integer_type_node;
            }
        }
    }

  if (TREE_CODE (decl) == FUNCTION_DECL
      && DECL_DECLARED_INLINE_P (decl)
      && DECL_UNINLINABLE (decl)
      && lookup_attribute ("noinline", DECL_ATTRIBUTES (decl)))
    warning (OPT_Wattributes, "inline function %q+D given attribute noinline",
             decl);

  /* Add this decl to the current scope.
     TEM may equal DECL or it may be a previous decl of the same name.  */
  tem = pushdecl (decl);

  if (initialized && DECL_EXTERNAL (tem))
    {
      DECL_EXTERNAL (tem) = 0;
      TREE_STATIC (tem) = 1;
    }

  return tem;
}

/* Finish processing of a declaration;
   install its initial value.
   If the length of an array type is not known before,
   it must be determined now, from the initial value, or it is an error.  */

void
finish_decl (tree decl, tree init, tree asmspec_tree)
{
  tree type = TREE_TYPE (decl);
  int was_incomplete = (DECL_SIZE (decl) == 0);
  const char *asmspec = 0;

  /* If a name was specified, get the string.  */
  if ((TREE_CODE (decl) == FUNCTION_DECL || TREE_CODE (decl) == VAR_DECL)
      && DECL_FILE_SCOPE_P (decl))
    asmspec_tree = maybe_apply_renaming_pragma (decl, asmspec_tree);
  if (asmspec_tree)
    asmspec = TREE_STRING_POINTER (asmspec_tree);

  /* If `start_decl' didn't like having an initialization, ignore it now.  */
  if (init != 0 && DECL_INITIAL (decl) == 0)
    init = 0;

  /* Don't crash if parm is initialized.  */
  if (TREE_CODE (decl) == PARM_DECL)
    init = 0;

  if (init)
    store_init_value (decl, init);

  if (c_dialect_objc () && (TREE_CODE (decl) == VAR_DECL
                            || TREE_CODE (decl) == FUNCTION_DECL
                            || TREE_CODE (decl) == FIELD_DECL))
    objc_check_decl (decl);

  /* Deduce size of array from initialization, if not already known.  */
  if (TREE_CODE (type) == ARRAY_TYPE
      && TYPE_DOMAIN (type) == 0
      && TREE_CODE (decl) != TYPE_DECL)
    {
      bool do_default
        = (TREE_STATIC (decl)
           /* Even if pedantic, an external linkage array
              may have incomplete type at first.  */
           ? pedantic && !TREE_PUBLIC (decl)
           : !DECL_EXTERNAL (decl));
      int failure
        = complete_array_type (&TREE_TYPE (decl), DECL_INITIAL (decl),
                               do_default);

      /* Get the completed type made by complete_array_type.  */
      type = TREE_TYPE (decl);

      switch (failure)
        {
        case 1:
          error ("initializer fails to determine size of %q+D", decl);
          break;

        case 2:
          if (do_default)
            error ("array size missing in %q+D", decl);
          /* If a `static' var's size isn't known,
             make it extern as well as static, so it does not get
             allocated.
             If it is not `static', then do not mark extern;
             finish_incomplete_decl will give it a default size
             and it will get allocated.  */
          else if (!pedantic && TREE_STATIC (decl) && !TREE_PUBLIC (decl))
            DECL_EXTERNAL (decl) = 1;
          break;

        case 3:
          error ("zero or negative size array %q+D", decl);
          break;

        case 0:
          /* For global variables, update the copy of the type that
             exists in the binding.  */
          if (TREE_PUBLIC (decl))
            {
              struct c_binding *b_ext = I_SYMBOL_BINDING (DECL_NAME (decl));
              while (b_ext && !B_IN_EXTERNAL_SCOPE (b_ext))
                b_ext = b_ext->shadowed;
              if (b_ext)
                {
                  if (b_ext->type)
                    b_ext->type = composite_type (b_ext->type, type);
                  else
                    b_ext->type = type;
                }
            }
          break;

        default:
          gcc_unreachable ();
        }

      if (DECL_INITIAL (decl))
        TREE_TYPE (DECL_INITIAL (decl)) = type;

      layout_decl (decl, 0);
    }

  if (TREE_CODE (decl) == VAR_DECL)
    {
      if (DECL_SIZE (decl) == 0 && TREE_TYPE (decl) != error_mark_node
          && COMPLETE_TYPE_P (TREE_TYPE (decl)))
        layout_decl (decl, 0);

      if (DECL_SIZE (decl) == 0
          /* Don't give an error if we already gave one earlier.  */
          && TREE_TYPE (decl) != error_mark_node
          && (TREE_STATIC (decl)
              /* A static variable with an incomplete type
                 is an error if it is initialized.
                 Also if it is not file scope.
                 Otherwise, let it through, but if it is not `extern'
                 then it may cause an error message later.  */
              ? (DECL_INITIAL (decl) != 0
                 || !DECL_FILE_SCOPE_P (decl))
              /* An automatic variable with an incomplete type
                 is an error.  */
              : !DECL_EXTERNAL (decl)))
         {
           error ("storage size of %q+D isn%'t known", decl);
           TREE_TYPE (decl) = error_mark_node;
         }

      if ((DECL_EXTERNAL (decl) || TREE_STATIC (decl))
          && DECL_SIZE (decl) != 0)
        {
          if (TREE_CODE (DECL_SIZE (decl)) == INTEGER_CST)
            constant_expression_warning (DECL_SIZE (decl));
          else
            error ("storage size of %q+D isn%'t constant", decl);
        }

      if (TREE_USED (type))
        TREE_USED (decl) = 1;
    }

  /* If this is a function and an assembler name is specified, reset DECL_RTL
     so we can give it its new name.  Also, update built_in_decls if it
     was a normal built-in.  */
  if (TREE_CODE (decl) == FUNCTION_DECL && asmspec)
    {
      if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL)
        set_builtin_user_assembler_name (decl, asmspec);
      set_user_assembler_name (decl, asmspec);
    }

  /* If #pragma weak was used, mark the decl weak now.  */
  maybe_apply_pragma_weak (decl);

  /* If this is a variable definition, determine its ELF visibility.  */
  if (TREE_CODE (decl) == VAR_DECL 
      && TREE_STATIC (decl) 
      && !DECL_EXTERNAL (decl))
    c_determine_visibility (decl);

  /* Output the assembler code and/or RTL code for variables and functions,
     unless the type is an undefined structure or union.
     If not, it will get done when the type is completed.  */

  if (TREE_CODE (decl) == VAR_DECL || TREE_CODE (decl) == FUNCTION_DECL)
    {
      /* This is a no-op in c-lang.c or something real in objc-act.c.  */
      if (c_dialect_objc ())
        objc_check_decl (decl);

      if (asmspec) 
        {
          /* If this is not a static variable, issue a warning.
             It doesn't make any sense to give an ASMSPEC for an
             ordinary, non-register local variable.  Historically,
             GCC has accepted -- but ignored -- the ASMSPEC in
             this case.  */
          if (!DECL_FILE_SCOPE_P (decl)
              && TREE_CODE (decl) == VAR_DECL
              && !C_DECL_REGISTER (decl)
              && !TREE_STATIC (decl))
            warning (0, "ignoring asm-specifier for non-static local "
                     "variable %q+D", decl);
          else if (C_DECL_REGISTER (decl))
            change_decl_assembler_name (decl, get_identifier (asmspec));
          else
            set_user_assembler_name (decl, asmspec);
        }
      
      if (DECL_FILE_SCOPE_P (decl))
        {
          if (DECL_INITIAL (decl) == NULL_TREE
              || DECL_INITIAL (decl) == error_mark_node)
            /* Don't output anything
               when a tentative file-scope definition is seen.
               But at end of compilation, do output code for them.  */
            DECL_DEFER_OUTPUT (decl) = 1;
          rest_of_decl_compilation (decl, true, 0);
        }
      else
        {
          /* In conjunction with an ASMSPEC, the `register'
             keyword indicates that we should place the variable
             in a particular register.  */
          if (asmspec && C_DECL_REGISTER (decl))
            {
              DECL_HARD_REGISTER (decl) = 1;
              /* This cannot be done for a structure with volatile
                 fields, on which DECL_REGISTER will have been
                 reset.  */
              if (!DECL_REGISTER (decl))
                error ("cannot put object with volatile field into register");
            }

          if (TREE_CODE (decl) != FUNCTION_DECL)
            {
              /* If we're building a variable sized type, and we might be
                 reachable other than via the top of the current binding
                 level, then create a new BIND_EXPR so that we deallocate
                 the object at the right time.  */
              /* Note that DECL_SIZE can be null due to errors.  */
              if (DECL_SIZE (decl)
                  && !TREE_CONSTANT (DECL_SIZE (decl))
                  && STATEMENT_LIST_HAS_LABEL (cur_stmt_list))
                {
                  tree bind;
                  bind = build3 (BIND_EXPR, void_type_node, NULL, NULL, NULL);
                  TREE_SIDE_EFFECTS (bind) = 1;
                  add_stmt (bind);
                  BIND_EXPR_BODY (bind) = push_stmt_list ();
                }
              add_stmt (build_stmt (DECL_EXPR, decl));
            }
        }
  

      if (!DECL_FILE_SCOPE_P (decl))
        {
          /* Recompute the RTL of a local array now
             if it used to be an incomplete type.  */
          if (was_incomplete
              && !TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
            {
              /* If we used it already as memory, it must stay in memory.  */
              TREE_ADDRESSABLE (decl) = TREE_USED (decl);
              /* If it's still incomplete now, no init will save it.  */