[pf3gnuchains/gcc-fork.git] / gcc / cp / 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, 2006, 2007, 2008, 2009, 2010
   Free Software Foundation, Inc.
   Contributed by Michael Tiemann (tiemann@cygnus.com)

This file is part of GCC.

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

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

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


/* 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 "tm.h"
#include "tree.h"
#include "flags.h"
#include "cp-tree.h"
#include "tree-iterator.h"
#include "tree-inline.h"
#include "decl.h"
#include "intl.h"
#include "output.h"
#include "toplev.h"
#include "hashtab.h"
#include "tm_p.h"
#include "target.h"
#include "c-family/c-common.h"
#include "c-family/c-objc.h"
#include "c-family/c-pragma.h"
#include "diagnostic.h"
#include "intl.h"
#include "debug.h"
#include "timevar.h"
#include "pointer-set.h"
#include "splay-tree.h"
#include "plugin.h"

/* Possible cases of bad specifiers type used by bad_specifiers. */
enum bad_spec_place {
  BSP_VAR,    /* variable */
  BSP_PARM,   /* parameter */
  BSP_TYPE,   /* type */
  BSP_FIELD   /* field */
};

static tree grokparms (tree parmlist, tree *);
static const char *redeclaration_error_message (tree, tree);

static int decl_jump_unsafe (tree);
static void require_complete_types_for_parms (tree);
static int ambi_op_p (enum tree_code);
static int unary_op_p (enum tree_code);
static void push_local_name (tree);
static tree grok_reference_init (tree, tree, tree, tree *);
static tree grokvardecl (tree, tree, const cp_decl_specifier_seq *,
                         int, int, tree);
static void record_unknown_type (tree, const char *);
static tree builtin_function_1 (tree, tree, bool);
static tree build_library_fn_1 (tree, enum tree_code, tree);
static int member_function_or_else (tree, tree, enum overload_flags);
static void bad_specifiers (tree, enum bad_spec_place, int, int, int, int,
                            int);
static void check_for_uninitialized_const_var (tree);
static hashval_t typename_hash (const void *);
static int typename_compare (const void *, const void *);
static tree local_variable_p_walkfn (tree *, int *, void *);
static tree record_builtin_java_type (const char *, int);
static const char *tag_name (enum tag_types);
static tree lookup_and_check_tag (enum tag_types, tree, tag_scope, bool);
static int walk_namespaces_r (tree, walk_namespaces_fn, void *);
static void maybe_deduce_size_from_array_init (tree, tree);
static void layout_var_decl (tree);
static tree check_initializer (tree, tree, int, tree *);
static void make_rtl_for_nonlocal_decl (tree, tree, const char *);
static void save_function_data (tree);
static void copy_type_enum (tree , tree);
static void check_function_type (tree, tree);
static void finish_constructor_body (void);
static void begin_destructor_body (void);
static void finish_destructor_body (void);
static void record_key_method_defined (tree);
static tree create_array_type_for_decl (tree, tree, tree);
static tree get_atexit_node (void);
static tree get_dso_handle_node (void);
static tree start_cleanup_fn (void);
static void end_cleanup_fn (void);
static tree cp_make_fname_decl (location_t, tree, int);
static void initialize_predefined_identifiers (void);
static tree check_special_function_return_type
        (special_function_kind, tree, tree);
static tree push_cp_library_fn (enum tree_code, tree);
static tree build_cp_library_fn (tree, enum tree_code, tree);
static void store_parm_decls (tree);
static void initialize_local_var (tree, tree);
static void expand_static_init (tree, tree);

/* The following symbols are subsumed in the cp_global_trees array, and
   listed here individually for documentation purposes.

   C++ extensions
        tree wchar_decl_node;

        tree vtable_entry_type;
        tree delta_type_node;
        tree __t_desc_type_node;

        tree class_type_node;
        tree unknown_type_node;

   Array type `vtable_entry_type[]'

        tree vtbl_type_node;
        tree vtbl_ptr_type_node;

   Namespaces,

        tree std_node;
        tree abi_node;

   A FUNCTION_DECL which can call `abort'.  Not necessarily the
   one that the user will declare, but sufficient to be called
   by routines that want to abort the program.

        tree abort_fndecl;

   The FUNCTION_DECL for the default `::operator delete'.

        tree global_delete_fndecl;

   Used by RTTI
        tree type_info_type_node, tinfo_decl_id, tinfo_decl_type;
        tree tinfo_var_id;  */

tree cp_global_trees[CPTI_MAX];

/* Indicates that there is a type value in some namespace, although
   that is not necessarily in scope at the moment.  */

tree global_type_node;

/* The node that holds the "name" of the global scope.  */
tree global_scope_name;

#define local_names cp_function_chain->x_local_names

/* A list of objects which have constructors or destructors
   which reside in the global scope.  The decl is stored in
   the TREE_VALUE slot and the initializer is stored
   in the TREE_PURPOSE slot.  */
tree static_aggregates;

/* -- end of C++ */

/* A node for the integer constant 2.  */

tree integer_two_node;

/* Used only for jumps to as-yet undefined labels, since jumps to
   defined labels can have their validity checked immediately.  */

struct GTY(()) named_label_use_entry {
  struct named_label_use_entry *next;
  /* The binding level to which this entry is *currently* attached.
     This is initially the binding level in which the goto appeared,
     but is modified as scopes are closed.  */
  struct cp_binding_level *binding_level;
  /* The head of the names list that was current when the goto appeared,
     or the inner scope popped.  These are the decls that will *not* be
     skipped when jumping to the label.  */
  tree names_in_scope;
  /* The location of the goto, for error reporting.  */
  location_t o_goto_locus;
  /* True if an OpenMP structured block scope has been closed since
     the goto appeared.  This means that the branch from the label will
     illegally exit an OpenMP scope.  */
  bool in_omp_scope;
};

/* A list of all LABEL_DECLs in the function that have names.  Here so
   we can clear out their names' definitions at the end of the
   function, and so we can check the validity of jumps to these labels.  */

struct GTY(()) named_label_entry {
  /* The decl itself.  */
  tree label_decl;

  /* The binding level to which the label is *currently* attached.
     This is initially set to the binding level in which the label
     is defined, but is modified as scopes are closed.  */
  struct cp_binding_level *binding_level;
  /* The head of the names list that was current when the label was
     defined, or the inner scope popped.  These are the decls that will
     be skipped when jumping to the label.  */
  tree names_in_scope;
  /* A vector of all decls from all binding levels that would be
     crossed by a backward branch to the label.  */
  VEC(tree,gc) *bad_decls;

  /* A list of uses of the label, before the label is defined.  */
  struct named_label_use_entry *uses;

  /* The following bits are set after the label is defined, and are
     updated as scopes are popped.  They indicate that a backward jump
     to the label will illegally enter a scope of the given flavor.  */
  bool in_try_scope;
  bool in_catch_scope;
  bool in_omp_scope;
};

#define named_labels cp_function_chain->x_named_labels
\f
/* The number of function bodies which we are currently processing.
   (Zero if we are at namespace scope, one inside the body of a
   function, two inside the body of a function in a local class, etc.)  */
int function_depth;

/* To avoid unwanted recursion, finish_function defers all mark_used calls
   encountered during its execution until it finishes.  */
bool defer_mark_used_calls;
VEC(tree, gc) *deferred_mark_used_calls;

/* 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_state = DEPRECATED_NORMAL;

\f
/* A list of VAR_DECLs whose type was incomplete at the time the
   variable was declared.  */

typedef struct GTY(()) incomplete_var_d {
  tree decl;
  tree incomplete_type;
} incomplete_var;

DEF_VEC_O(incomplete_var);
DEF_VEC_ALLOC_O(incomplete_var,gc);

static GTY(()) VEC(incomplete_var,gc) *incomplete_vars;
\f
/* Returns the kind of template specialization we are currently
   processing, given that it's declaration contained N_CLASS_SCOPES
   explicit scope qualifications.  */

tmpl_spec_kind
current_tmpl_spec_kind (int n_class_scopes)
{
  int n_template_parm_scopes = 0;
  int seen_specialization_p = 0;
  int innermost_specialization_p = 0;
  struct cp_binding_level *b;

  /* Scan through the template parameter scopes.  */
  for (b = current_binding_level;
       b->kind == sk_template_parms;
       b = b->level_chain)
    {
      /* If we see a specialization scope inside a parameter scope,
         then something is wrong.  That corresponds to a declaration
         like:

            template <class T> template <> ...

         which is always invalid since [temp.expl.spec] forbids the
         specialization of a class member template if the enclosing
         class templates are not explicitly specialized as well.  */
      if (b->explicit_spec_p)
        {
          if (n_template_parm_scopes == 0)
            innermost_specialization_p = 1;
          else
            seen_specialization_p = 1;
        }
      else if (seen_specialization_p == 1)
        return tsk_invalid_member_spec;

      ++n_template_parm_scopes;
    }

  /* Handle explicit instantiations.  */
  if (processing_explicit_instantiation)
    {
      if (n_template_parm_scopes != 0)
        /* We've seen a template parameter list during an explicit
           instantiation.  For example:

             template <class T> template void f(int);

           This is erroneous.  */
        return tsk_invalid_expl_inst;
      else
        return tsk_expl_inst;
    }

  if (n_template_parm_scopes < n_class_scopes)
    /* We've not seen enough template headers to match all the
       specialized classes present.  For example:

         template <class T> void R<T>::S<T>::f(int);

       This is invalid; there needs to be one set of template
       parameters for each class.  */
    return tsk_insufficient_parms;
  else if (n_template_parm_scopes == n_class_scopes)
    /* We're processing a non-template declaration (even though it may
       be a member of a template class.)  For example:

         template <class T> void S<T>::f(int);

       The `class T' matches the `S<T>', leaving no template headers
       corresponding to the `f'.  */
    return tsk_none;
  else if (n_template_parm_scopes > n_class_scopes + 1)
    /* We've got too many template headers.  For example:

         template <> template <class T> void f (T);

       There need to be more enclosing classes.  */
    return tsk_excessive_parms;
  else
    /* This must be a template.  It's of the form:

         template <class T> template <class U> void S<T>::f(U);

       This is a specialization if the innermost level was a
       specialization; otherwise it's just a definition of the
       template.  */
    return innermost_specialization_p ? tsk_expl_spec : tsk_template;
}

/* Exit the current scope.  */

void
finish_scope (void)
{
  poplevel (0, 0, 0);
}

/* When a label goes out of scope, check to see if that label was used
   in a valid manner, and issue any appropriate warnings or errors.  */

static void
pop_label (tree label, tree old_value)
{
  if (!processing_template_decl)
    {
      if (DECL_INITIAL (label) == NULL_TREE)
        {
          location_t location;

          error ("label %q+D used but not defined", label);
          location = input_location; /* FIXME want (input_filename, (line)0) */
          /* Avoid crashing later.  */
          define_label (location, DECL_NAME (label));
        }
      else 
        warn_for_unused_label (label);
    }

  SET_IDENTIFIER_LABEL_VALUE (DECL_NAME (label), old_value);
}

/* At the end of a function, all labels declared within the function
   go out of scope.  BLOCK is the top-level block for the
   function.  */

static int
pop_labels_1 (void **slot, void *data)
{
  struct named_label_entry *ent = (struct named_label_entry *) *slot;
  tree block = (tree) data;

  pop_label (ent->label_decl, NULL_TREE);

  /* Put the labels into the "variables" of the top-level block,
     so debugger can see them.  */
  DECL_CHAIN (ent->label_decl) = BLOCK_VARS (block);
  BLOCK_VARS (block) = ent->label_decl;

  htab_clear_slot (named_labels, slot);

  return 1;
}

static void
pop_labels (tree block)
{
  if (named_labels)
    {
      htab_traverse (named_labels, pop_labels_1, block);
      named_labels = NULL;
    }
}

/* At the end of a block with local labels, restore the outer definition.  */

static void
pop_local_label (tree label, tree old_value)
{
  struct named_label_entry dummy;
  void **slot;

  pop_label (label, old_value);

  dummy.label_decl = label;
  slot = htab_find_slot (named_labels, &dummy, NO_INSERT);
  htab_clear_slot (named_labels, slot);
}

/* The following two routines are used to interface to Objective-C++.
   The binding level is purposely treated as an opaque type.  */

void *
objc_get_current_scope (void)
{
  return current_binding_level;
}

/* The following routine is used by the NeXT-style SJLJ exceptions;
   variables get marked 'volatile' so as to not be clobbered by
   _setjmp()/_longjmp() calls.  All variables in the current scope,
   as well as parent scopes up to (but not including) ENCLOSING_BLK
   shall be thusly marked.  */

void
objc_mark_locals_volatile (void *enclosing_blk)
{
  struct cp_binding_level *scope;

  for (scope = current_binding_level;
       scope && scope != enclosing_blk;
       scope = scope->level_chain)
    {
      tree decl;

      for (decl = scope->names; decl; decl = TREE_CHAIN (decl))
        objc_volatilize_decl (decl);

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

/* Update data for defined and undefined labels when leaving a scope.  */

static int
poplevel_named_label_1 (void **slot, void *data)
{
  struct named_label_entry *ent = (struct named_label_entry *) *slot;
  struct cp_binding_level *bl = (struct cp_binding_level *) data;
  struct cp_binding_level *obl = bl->level_chain;

  if (ent->binding_level == bl)
    {
      tree decl;

      /* ENT->NAMES_IN_SCOPE may contain a mixture of DECLs and
         TREE_LISTs representing OVERLOADs, so be careful.  */
      for (decl = ent->names_in_scope; decl; decl = (DECL_P (decl)
                                                     ? DECL_CHAIN (decl)
                                                     : TREE_CHAIN (decl)))
        if (decl_jump_unsafe (decl))
          VEC_safe_push (tree, gc, ent->bad_decls, decl);

      ent->binding_level = obl;
      ent->names_in_scope = obl->names;
      switch (bl->kind)
        {
        case sk_try:
          ent->in_try_scope = true;
          break;
        case sk_catch:
          ent->in_catch_scope = true;
          break;
        case sk_omp:
          ent->in_omp_scope = true;
          break;
        default:
          break;
        }
    }
  else if (ent->uses)
    {
      struct named_label_use_entry *use;

      for (use = ent->uses; use ; use = use->next)
        if (use->binding_level == bl)
          {
            use->binding_level = obl;
            use->names_in_scope = obl->names;
            if (bl->kind == sk_omp)
              use->in_omp_scope = true;
          }
    }

  return 1;
}

/* Saved errorcount to avoid -Wunused-but-set-{parameter,variable} warnings
   when errors were reported, except for -Werror-unused-but-set-*.  */
static int unused_but_set_errorcount;

/* Exit a binding level.
   Pop the level off, and restore the state of the identifier-decl mappings
   that were in effect when this level was entered.

   If KEEP == 1, this level had explicit declarations, so
   and create a "block" (a BLOCK node) for the level
   to record its declarations and subblocks for symbol table output.

   If FUNCTIONBODY is nonzero, this level is the body of a function,
   so create a block as if KEEP were set and also clear out all
   label names.

   If REVERSE is nonzero, reverse the order of decls before putting
   them into the BLOCK.  */

tree
poplevel (int keep, int reverse, int functionbody)
{
  tree link;
  /* The chain of decls was accumulated in reverse order.
     Put it into forward order, just for cleanliness.  */
  tree decls;
  tree subblocks;
  tree block;
  tree decl;
  int leaving_for_scope;
  scope_kind kind;
  unsigned ix;
  cp_label_binding *label_bind;

  timevar_push (TV_NAME_LOOKUP);
 restart:

  block = NULL_TREE;

  gcc_assert (current_binding_level->kind != sk_class);

  if (current_binding_level->kind == sk_cleanup)
    functionbody = 0;
  subblocks = functionbody >= 0 ? current_binding_level->blocks : 0;

  gcc_assert (!VEC_length(cp_class_binding,
                          current_binding_level->class_shadowed));

  /* We used to use KEEP == 2 to indicate that the new block should go
     at the beginning of the list of blocks at this binding level,
     rather than the end.  This hack is no longer used.  */
  gcc_assert (keep == 0 || keep == 1);

  if (current_binding_level->keep)
    keep = 1;

  /* Any uses of undefined labels, and any defined labels, now operate
     under constraints of next binding contour.  */
  if (cfun && !functionbody && named_labels)
    htab_traverse (named_labels, poplevel_named_label_1,
                   current_binding_level);

  /* Get the decls in the order they were written.
     Usually current_binding_level->names is in reverse order.
     But parameter decls were previously put in forward order.  */

  if (reverse)
    current_binding_level->names
      = decls = nreverse (current_binding_level->names);
  else
    decls = current_binding_level->names;

  /* If there were any declarations or structure tags in that level,
     or if this level is a function body,
     create a BLOCK to record them for the life of this function.  */
  block = NULL_TREE;
  if (keep == 1 || functionbody)
    block = make_node (BLOCK);
  if (block != NULL_TREE)
    {
      BLOCK_VARS (block) = decls;
      BLOCK_SUBBLOCKS (block) = subblocks;
    }

  /* In each subblock, record that this is its superior.  */
  if (keep >= 0)
    for (link = subblocks; link; link = BLOCK_CHAIN (link))
      BLOCK_SUPERCONTEXT (link) = block;

  /* We still support the old for-scope rules, whereby the variables
     in a for-init statement were in scope after the for-statement
     ended.  We only use the new rules if flag_new_for_scope is
     nonzero.  */
  leaving_for_scope
    = current_binding_level->kind == sk_for && flag_new_for_scope == 1;

  /* Before we remove the declarations first check for unused variables.  */
  if ((warn_unused_variable || warn_unused_but_set_variable)
      && !processing_template_decl)
    for (decl = getdecls (); decl; decl = TREE_CHAIN (decl))
      if (TREE_CODE (decl) == VAR_DECL
          && (! TREE_USED (decl) || !DECL_READ_P (decl))
          && ! DECL_IN_SYSTEM_HEADER (decl)
          && DECL_NAME (decl) && ! DECL_ARTIFICIAL (decl))
        {
          if (! TREE_USED (decl))
            warning (OPT_Wunused_variable, "unused variable %q+D", decl);
          else if (DECL_CONTEXT (decl) == current_function_decl
                   && TREE_TYPE (decl) != error_mark_node
                   && TREE_CODE (TREE_TYPE (decl)) != REFERENCE_TYPE
                   && errorcount == unused_but_set_errorcount
                   && (!CLASS_TYPE_P (TREE_TYPE (decl))
                       || !TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (decl))))
            {
              warning (OPT_Wunused_but_set_variable,
                       "variable %q+D set but not used", decl); 
              unused_but_set_errorcount = errorcount;
            }
        }

  /* Remove declarations for all the DECLs in this level.  */
  for (link = decls; link; link = TREE_CHAIN (link))
    {
      if (leaving_for_scope && TREE_CODE (link) == VAR_DECL
          && DECL_NAME (link))
        {
          tree name = DECL_NAME (link);
          cxx_binding *ob;
          tree ns_binding;

          ob = outer_binding (name,
                              IDENTIFIER_BINDING (name),
                              /*class_p=*/true);
          if (!ob)
            ns_binding = IDENTIFIER_NAMESPACE_VALUE (name);
          else
            ns_binding = NULL_TREE;

          if (ob && ob->scope == current_binding_level->level_chain)
            /* We have something like:

                 int i;
                 for (int i; ;);

               and we are leaving the `for' scope.  There's no reason to
               keep the binding of the inner `i' in this case.  */
            pop_binding (name, link);
          else if ((ob && (TREE_CODE (ob->value) == TYPE_DECL))
                   || (ns_binding && TREE_CODE (ns_binding) == TYPE_DECL))
            /* Here, we have something like:

                 typedef int I;

                 void f () {
                   for (int I; ;);
                 }

               We must pop the for-scope binding so we know what's a
               type and what isn't.  */
            pop_binding (name, link);
          else
            {
              /* Mark this VAR_DECL as dead so that we can tell we left it
                 there only for backward compatibility.  */
              DECL_DEAD_FOR_LOCAL (link) = 1;

              /* Keep track of what should have happened when we
                 popped the binding.  */
              if (ob && ob->value)
                {
                  SET_DECL_SHADOWED_FOR_VAR (link, ob->value);
                  DECL_HAS_SHADOWED_FOR_VAR_P (link) = 1;
                }

              /* Add it to the list of dead variables in the next
                 outermost binding to that we can remove these when we
                 leave that binding.  */
              VEC_safe_push (tree, gc,
                             current_binding_level->level_chain->dead_vars_from_for,
                             link);

              /* Although we don't pop the cxx_binding, we do clear
                 its SCOPE since the scope is going away now.  */
              IDENTIFIER_BINDING (name)->scope
                = current_binding_level->level_chain;
            }
        }
      else
        {
          tree name;

          /* Remove the binding.  */
          decl = link;

          if (TREE_CODE (decl) == TREE_LIST)
            decl = TREE_VALUE (decl);
          name = decl;

          if (TREE_CODE (name) == OVERLOAD)
            name = OVL_FUNCTION (name);

          gcc_assert (DECL_P (name));
          pop_binding (DECL_NAME (name), decl);
        }
    }

  /* Remove declarations for any `for' variables from inner scopes
     that we kept around.  */
  FOR_EACH_VEC_ELT_REVERSE (tree, current_binding_level->dead_vars_from_for,
                            ix, decl)
    pop_binding (DECL_NAME (decl), decl);

  /* Restore the IDENTIFIER_TYPE_VALUEs.  */
  for (link = current_binding_level->type_shadowed;
       link; link = TREE_CHAIN (link))
    SET_IDENTIFIER_TYPE_VALUE (TREE_PURPOSE (link), TREE_VALUE (link));

  /* Restore the IDENTIFIER_LABEL_VALUEs for local labels.  */
  FOR_EACH_VEC_ELT_REVERSE (cp_label_binding,
                            current_binding_level->shadowed_labels,
                            ix, label_bind)
    pop_local_label (label_bind->label, label_bind->prev_value);

  /* There may be OVERLOADs (wrapped in TREE_LISTs) on the BLOCK_VARs
     list if a `using' declaration put them there.  The debugging
     back ends won't understand OVERLOAD, so we remove them here.
     Because the BLOCK_VARS are (temporarily) shared with
     CURRENT_BINDING_LEVEL->NAMES we must do this fixup after we have
     popped all the bindings.  */
  if (block)
    {
      tree* d;

      for (d = &BLOCK_VARS (block); *d; )
        {
          if (TREE_CODE (*d) == TREE_LIST)
            *d = TREE_CHAIN (*d);
          else
            d = &DECL_CHAIN (*d);
        }
    }

  /* If the level being exited is the top level of a function,
     check over all the labels.  */
  if (functionbody)
    {
      /* Since this is the top level block of a function, the vars are
         the function's parameters.  Don't leave them in the BLOCK
         because they are found in the FUNCTION_DECL instead.  */
      BLOCK_VARS (block) = 0;
      pop_labels (block);
    }

  kind = current_binding_level->kind;
  if (kind == sk_cleanup)
    {
      tree stmt;

      /* If this is a temporary binding created for a cleanup, then we'll
         have pushed a statement list level.  Pop that, create a new
         BIND_EXPR for the block, and insert it into the stream.  */
      stmt = pop_stmt_list (current_binding_level->statement_list);
      stmt = c_build_bind_expr (input_location, block, stmt);
      add_stmt (stmt);
    }

  leave_scope ();
  if (functionbody)
    {
      /* The current function is being defined, so its DECL_INITIAL
         should be error_mark_node.  */
      gcc_assert (DECL_INITIAL (current_function_decl) == error_mark_node);
      DECL_INITIAL (current_function_decl) = block;
    }
  else if (block)
    current_binding_level->blocks
      = chainon (current_binding_level->blocks, block);

  /* If we did not make a block for the level just exited,
     any blocks made for inner levels
     (since they cannot be recorded as subblocks in that level)
     must be carried forward so they will later become subblocks
     of something else.  */
  else if (subblocks)
    current_binding_level->blocks
      = chainon (current_binding_level->blocks, subblocks);

  /* Each and every BLOCK node created here in `poplevel' is important
     (e.g. for proper debugging information) so if we created one
     earlier, mark it as "used".  */
  if (block)
    TREE_USED (block) = 1;

  /* All temporary bindings created for cleanups are popped silently.  */
  if (kind == sk_cleanup)
    goto restart;

  POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, block);
}

/* Walk all the namespaces contained NAMESPACE, including NAMESPACE
   itself, calling F for each.  The DATA is passed to F as well.  */

static int
walk_namespaces_r (tree name_space, walk_namespaces_fn f, void* data)
{
  int result = 0;
  tree current = NAMESPACE_LEVEL (name_space)->namespaces;

  result |= (*f) (name_space, data);

  for (; current; current = DECL_CHAIN (current))
    result |= walk_namespaces_r (current, f, data);

  return result;
}

/* Walk all the namespaces, calling F for each.  The DATA is passed to
   F as well.  */

int
walk_namespaces (walk_namespaces_fn f, void* data)
{
  return walk_namespaces_r (global_namespace, f, data);
}

/* Call wrapup_globals_declarations for the globals in NAMESPACE.  If
   DATA is non-NULL, this is the last time we will call
   wrapup_global_declarations for this NAMESPACE.  */

int
wrapup_globals_for_namespace (tree name_space, void* data)
{
  struct cp_binding_level *level = NAMESPACE_LEVEL (name_space);
  VEC(tree,gc) *statics = level->static_decls;
  tree *vec = VEC_address (tree, statics);
  int len = VEC_length (tree, statics);
  int last_time = (data != 0);

  if (last_time)
    {
      check_global_declarations (vec, len);
      emit_debug_global_declarations (vec, len);
      return 0;
    }

  /* Write out any globals that need to be output.  */
  return wrapup_global_declarations (vec, len);
}

\f
/* In C++, you don't have to write `struct S' to refer to `S'; you
   can just use `S'.  We accomplish this by creating a TYPE_DECL as
   if the user had written `typedef struct S S'.  Create and return
   the TYPE_DECL for TYPE.  */

tree
create_implicit_typedef (tree name, tree type)
{
  tree decl;

  decl = build_decl (input_location, TYPE_DECL, name, type);
  DECL_ARTIFICIAL (decl) = 1;
  /* There are other implicit type declarations, like the one *within*
     a class that allows you to write `S::S'.  We must distinguish
     amongst these.  */
  SET_DECL_IMPLICIT_TYPEDEF_P (decl);
  TYPE_NAME (type) = decl;
  TYPE_STUB_DECL (type) = decl;

  return decl;
}

/* Remember a local name for name-mangling purposes.  */

static void
push_local_name (tree decl)
{
  size_t i, nelts;
  tree t, name;

  timevar_push (TV_NAME_LOOKUP);

  name = DECL_NAME (decl);

  nelts = VEC_length (tree, local_names);
  for (i = 0; i < nelts; i++)
    {
      t = VEC_index (tree, local_names, i);
      if (DECL_NAME (t) == name)
        {
          if (!DECL_LANG_SPECIFIC (decl))
            retrofit_lang_decl (decl);
          DECL_LANG_SPECIFIC (decl)->u.base.u2sel = 1;
          if (DECL_LANG_SPECIFIC (t))
            DECL_DISCRIMINATOR (decl) = DECL_DISCRIMINATOR (t) + 1;
          else
            DECL_DISCRIMINATOR (decl) = 1;

          VEC_replace (tree, local_names, i, decl);
          timevar_pop (TV_NAME_LOOKUP);
          return;
        }
    }

  VEC_safe_push (tree, gc, local_names, decl);
  timevar_pop (TV_NAME_LOOKUP);
}
\f
/* Subroutine of duplicate_decls: return truthvalue of whether
   or not types of these decls match.

   For C++, we must compare the parameter list so that `int' can match
   `int&' in a parameter position, but `int&' is not confused with
   `const int&'.  */

int
decls_match (tree newdecl, tree olddecl)
{
  int types_match;

  if (newdecl == olddecl)
    return 1;

  if (TREE_CODE (newdecl) != TREE_CODE (olddecl))
    /* If the two DECLs are not even the same kind of thing, we're not
       interested in their types.  */
    return 0;

  if (TREE_CODE (newdecl) == FUNCTION_DECL)
    {
      tree f1 = TREE_TYPE (newdecl);
      tree f2 = TREE_TYPE (olddecl);
      tree p1 = TYPE_ARG_TYPES (f1);
      tree p2 = TYPE_ARG_TYPES (f2);

      /* Specializations of different templates are different functions
         even if they have the same type.  */
      tree t1 = (DECL_USE_TEMPLATE (newdecl)
                 ? DECL_TI_TEMPLATE (newdecl)
                 : NULL_TREE);
      tree t2 = (DECL_USE_TEMPLATE (olddecl)
                 ? DECL_TI_TEMPLATE (olddecl)
                 : NULL_TREE);
      if (t1 != t2)
        return 0;

      if (CP_DECL_CONTEXT (newdecl) != CP_DECL_CONTEXT (olddecl)
          && ! (DECL_EXTERN_C_P (newdecl)
                && DECL_EXTERN_C_P (olddecl)))
        return 0;

#ifdef NO_IMPLICIT_EXTERN_C
      /* A new declaration doesn't match a built-in one unless it
         is also extern "C".  */
      if (DECL_IS_BUILTIN (olddecl)
          && DECL_EXTERN_C_P (olddecl) && !DECL_EXTERN_C_P (newdecl))
        return 0;
#endif

      if (TREE_CODE (f1) != TREE_CODE (f2))
        return 0;

      if (same_type_p (TREE_TYPE (f1), TREE_TYPE (f2)))
        {
          if (p2 == NULL_TREE && DECL_EXTERN_C_P (olddecl)
              && (DECL_BUILT_IN (olddecl)
#ifndef NO_IMPLICIT_EXTERN_C
                  || (DECL_IN_SYSTEM_HEADER (newdecl) && !DECL_CLASS_SCOPE_P (newdecl))
                  || (DECL_IN_SYSTEM_HEADER (olddecl) && !DECL_CLASS_SCOPE_P (olddecl))
#endif
              ))
            {
              types_match = self_promoting_args_p (p1);
              if (p1 == void_list_node)
                TREE_TYPE (newdecl) = TREE_TYPE (olddecl);
            }
#ifndef NO_IMPLICIT_EXTERN_C
          else if (p1 == NULL_TREE
                   && (DECL_EXTERN_C_P (olddecl)
                       && DECL_IN_SYSTEM_HEADER (olddecl)
                       && !DECL_CLASS_SCOPE_P (olddecl))
                   && (DECL_EXTERN_C_P (newdecl)
                       && DECL_IN_SYSTEM_HEADER (newdecl)
                       && !DECL_CLASS_SCOPE_P (newdecl)))
            {
              types_match = self_promoting_args_p (p2);
              TREE_TYPE (newdecl) = TREE_TYPE (olddecl);
            }
#endif
          else
            types_match = compparms (p1, p2);
        }
      else
        types_match = 0;
    }
  else if (TREE_CODE (newdecl) == TEMPLATE_DECL)
    {
      if (TREE_CODE (DECL_TEMPLATE_RESULT (newdecl))
          != TREE_CODE (DECL_TEMPLATE_RESULT (olddecl)))
        return 0;

      if (!comp_template_parms (DECL_TEMPLATE_PARMS (newdecl),
                                DECL_TEMPLATE_PARMS (olddecl)))
        return 0;

      if (TREE_CODE (DECL_TEMPLATE_RESULT (newdecl)) == TYPE_DECL)
        types_match = same_type_p (TREE_TYPE (DECL_TEMPLATE_RESULT (olddecl)),
                                   TREE_TYPE (DECL_TEMPLATE_RESULT (newdecl)));
      else
        types_match = decls_match (DECL_TEMPLATE_RESULT (olddecl),
                                   DECL_TEMPLATE_RESULT (newdecl));
    }
  else
    {
      /* Need to check scope for variable declaration (VAR_DECL).
         For typedef (TYPE_DECL), scope is ignored.  */
      if (TREE_CODE (newdecl) == VAR_DECL
          && CP_DECL_CONTEXT (newdecl) != CP_DECL_CONTEXT (olddecl)
          /* [dcl.link]
             Two declarations for an object with C language linkage
             with the same name (ignoring the namespace that qualify
             it) that appear in different namespace scopes refer to
             the same object.  */
          && !(DECL_EXTERN_C_P (olddecl) && DECL_EXTERN_C_P (newdecl)))
        return 0;

      if (TREE_TYPE (newdecl) == error_mark_node)
        types_match = TREE_TYPE (olddecl) == error_mark_node;
      else if (TREE_TYPE (olddecl) == NULL_TREE)
        types_match = TREE_TYPE (newdecl) == NULL_TREE;
      else if (TREE_TYPE (newdecl) == NULL_TREE)
        types_match = 0;
      else
        types_match = comptypes (TREE_TYPE (newdecl),
                                 TREE_TYPE (olddecl),
                                 COMPARE_REDECLARATION);
    }

  return types_match;
}

/* If NEWDECL is `static' and an `extern' was seen previously,
   warn about it.  OLDDECL is the previous declaration.

   Note that this does not apply to the C++ case of declaring
   a variable `extern const' and then later `const'.

   Don't complain about built-in functions, since they are beyond
   the user's control.  */

void
warn_extern_redeclared_static (tree newdecl, tree olddecl)
{
  if (TREE_CODE (newdecl) == TYPE_DECL
      || TREE_CODE (newdecl) == TEMPLATE_DECL
      || TREE_CODE (newdecl) == CONST_DECL
      || TREE_CODE (newdecl) == NAMESPACE_DECL)
    return;

  /* Don't get confused by static member functions; that's a different
     use of `static'.  */
  if (TREE_CODE (newdecl) == FUNCTION_DECL
      && DECL_STATIC_FUNCTION_P (newdecl))
    return;

  /* If the old declaration was `static', or the new one isn't, then
     then everything is OK.  */
  if (DECL_THIS_STATIC (olddecl) || !DECL_THIS_STATIC (newdecl))
    return;

  /* It's OK to declare a builtin function as `static'.  */
  if (TREE_CODE (olddecl) == FUNCTION_DECL
      && DECL_ARTIFICIAL (olddecl))
    return;

  permerror (input_location, "%qD was declared %<extern%> and later %<static%>", newdecl);
  permerror (input_location, "previous declaration of %q+D", olddecl);
}

/* NEW_DECL is a redeclaration of OLD_DECL; both are functions or
   function templates.  If their exception specifications do not
   match, issue a diagnostic.  */

static void
check_redeclaration_exception_specification (tree new_decl,
                                             tree old_decl)
{
  tree new_type;
  tree old_type;
  tree new_exceptions;
  tree old_exceptions;

  new_type = TREE_TYPE (new_decl);
  new_exceptions = TYPE_RAISES_EXCEPTIONS (new_type);
  old_type = TREE_TYPE (old_decl);
  old_exceptions = TYPE_RAISES_EXCEPTIONS (old_type);

  /* [except.spec]

     If any declaration of a function has an exception-specification,
     all declarations, including the definition and an explicit
     specialization, of that function shall have an
     exception-specification with the same set of type-ids.  */
  if ((pedantic || ! DECL_IN_SYSTEM_HEADER (old_decl))
      && ! DECL_IS_BUILTIN (old_decl)
      && flag_exceptions
      && !comp_except_specs (new_exceptions, old_exceptions, ce_normal))
    {
      error ("declaration of %qF has a different exception specifier",
             new_decl);
      error ("from previous declaration %q+F", old_decl);
    }
}

/* Return true if OLD_DECL and NEW_DECL agree on constexprness.
   Otherwise issue diagnostics.  */

static bool
validate_constexpr_redeclaration (tree old_decl, tree new_decl)
{
  old_decl = STRIP_TEMPLATE (old_decl);
  new_decl = STRIP_TEMPLATE (new_decl);
  if (!VAR_OR_FUNCTION_DECL_P (old_decl)
      || !VAR_OR_FUNCTION_DECL_P (new_decl))
    return true;
  if (DECL_DECLARED_CONSTEXPR_P (old_decl)
      == DECL_DECLARED_CONSTEXPR_P (new_decl))
    return true;
  if (TREE_CODE (old_decl) == FUNCTION_DECL && DECL_BUILT_IN (old_decl))
    {
      /* Hide a built-in declaration.  */
      DECL_DECLARED_CONSTEXPR_P (old_decl)
        = DECL_DECLARED_CONSTEXPR_P (new_decl);
      return true;
    }
  error ("redeclaration %qD differs in %<constexpr%>", new_decl);
  error ("from previous declaration %q+D", old_decl);
  return false;
}

#define GNU_INLINE_P(fn) (DECL_DECLARED_INLINE_P (fn)                   \
                          && lookup_attribute ("gnu_inline",            \
                                               DECL_ATTRIBUTES (fn)))

/* If NEWDECL is a redeclaration of OLDDECL, merge the declarations.
   If the redeclaration is invalid, a diagnostic is issued, and the
   error_mark_node is returned.  Otherwise, OLDDECL is returned.

   If NEWDECL is not a redeclaration of OLDDECL, NULL_TREE is
   returned.

   NEWDECL_IS_FRIEND is true if NEWDECL was declared as a friend.  */

tree
duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
{
  unsigned olddecl_uid = DECL_UID (olddecl);
  int olddecl_friend = 0, types_match = 0, hidden_friend = 0;
  int new_defines_function = 0;
  tree new_template_info;

  if (newdecl == olddecl)
    return olddecl;

  types_match = decls_match (newdecl, olddecl);

  /* If either the type of the new decl or the type of the old decl is an
     error_mark_node, then that implies that we have already issued an
     error (earlier) for some bogus type specification, and in that case,
     it is rather pointless to harass the user with yet more error message
     about the same declaration, so just pretend the types match here.  */
  if (TREE_TYPE (newdecl) == error_mark_node
      || TREE_TYPE (olddecl) == error_mark_node)
    return error_mark_node;

  if (DECL_P (olddecl)
      && TREE_CODE (newdecl) == FUNCTION_DECL
      && TREE_CODE (olddecl) == FUNCTION_DECL
      && (DECL_UNINLINABLE (newdecl) || DECL_UNINLINABLE (olddecl)))
    {
      if (DECL_DECLARED_INLINE_P (newdecl)
          && DECL_UNINLINABLE (newdecl)
          && lookup_attribute ("noinline", DECL_ATTRIBUTES (newdecl)))
        /* Already warned elsewhere.  */;
      else if (DECL_DECLARED_INLINE_P (olddecl)
               && DECL_UNINLINABLE (olddecl)
               && lookup_attribute ("noinline", DECL_ATTRIBUTES (olddecl)))
        /* Already warned.  */;
      else if (DECL_DECLARED_INLINE_P (newdecl)
               && DECL_UNINLINABLE (olddecl)
               && lookup_attribute ("noinline", DECL_ATTRIBUTES (olddecl)))
        {
          warning (OPT_Wattributes, "function %q+D redeclared as inline",
                   newdecl);
          warning (OPT_Wattributes, "previous declaration of %q+D "
                   "with attribute noinline", olddecl);
        }
      else if (DECL_DECLARED_INLINE_P (olddecl)
               && DECL_UNINLINABLE (newdecl)
               && lookup_attribute ("noinline", DECL_ATTRIBUTES (newdecl)))
        {
          warning (OPT_Wattributes, "function %q+D redeclared with "
                   "attribute noinline", newdecl);
          warning (OPT_Wattributes, "previous declaration of %q+D was inline",
                   olddecl);
        }
    }

  /* Check for redeclaration and other discrepancies.  */
  if (TREE_CODE (olddecl) == FUNCTION_DECL
      && DECL_ARTIFICIAL (olddecl))
    {
      gcc_assert (!DECL_HIDDEN_FRIEND_P (olddecl));
      if (TREE_CODE (newdecl) != FUNCTION_DECL)
        {
          /* Avoid warnings redeclaring built-ins which have not been
             explicitly declared.  */
          if (DECL_ANTICIPATED (olddecl))
            return NULL_TREE;

          /* If you declare a built-in or predefined function name as static,
             the old definition is overridden, but optionally warn this was a
             bad choice of name.  */
          if (! TREE_PUBLIC (newdecl))
            {
              warning (OPT_Wshadow, 
                       DECL_BUILT_IN (olddecl)
                       ? G_("shadowing built-in function %q#D")
                       : G_("shadowing library function %q#D"), olddecl);
              /* Discard the old built-in function.  */
              return NULL_TREE;
            }
          /* If the built-in is not ansi, then programs can override
             it even globally without an error.  */
          else if (! DECL_BUILT_IN (olddecl))
            warning (0, "library function %q#D redeclared as non-function %q#D",
                     olddecl, newdecl);
          else
            {
              error ("declaration of %q#D", newdecl);
              error ("conflicts with built-in declaration %q#D",
                     olddecl);
            }
          return NULL_TREE;
        }
      else if (!types_match)
        {
          /* Avoid warnings redeclaring built-ins which have not been
             explicitly declared.  */
          if (DECL_ANTICIPATED (olddecl))
            {
              /* Deal with fileptr_type_node.  FILE type is not known
                 at the time we create the builtins.  */
              tree t1, t2;

              for (t1 = TYPE_ARG_TYPES (TREE_TYPE (newdecl)),
                   t2 = TYPE_ARG_TYPES (TREE_TYPE (olddecl));
                   t1 || t2;
                   t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
                if (!t1 || !t2)
                  break;
                else if (TREE_VALUE (t2) == fileptr_type_node)
                  {
                    tree t = TREE_VALUE (t1);

                    if (TREE_CODE (t) == POINTER_TYPE
                        && TYPE_NAME (TREE_TYPE (t))
                        && DECL_NAME (TYPE_NAME (TREE_TYPE (t)))
                           == get_identifier ("FILE")
                        && compparms (TREE_CHAIN (t1), TREE_CHAIN (t2)))
                      {
                        tree oldargs = TYPE_ARG_TYPES (TREE_TYPE (olddecl));

                        TYPE_ARG_TYPES (TREE_TYPE (olddecl))
                          = TYPE_ARG_TYPES (TREE_TYPE (newdecl));
                        types_match = decls_match (newdecl, olddecl);
                        if (types_match)
                          return duplicate_decls (newdecl, olddecl,
                                                  newdecl_is_friend);
                        TYPE_ARG_TYPES (TREE_TYPE (olddecl)) = oldargs;
                      }
                  }
                else if (! same_type_p (TREE_VALUE (t1), TREE_VALUE (t2)))
                  break;
            }
          else if ((DECL_EXTERN_C_P (newdecl)
                    && DECL_EXTERN_C_P (olddecl))
                   || compparms (TYPE_ARG_TYPES (TREE_TYPE (newdecl)),
                                 TYPE_ARG_TYPES (TREE_TYPE (olddecl))))
            {
              /* A near match; override the builtin.  */

              if (TREE_PUBLIC (newdecl))
                {
                  warning (0, "new declaration %q#D", newdecl);
                  warning (0, "ambiguates built-in declaration %q#D",
                           olddecl);
                }
              else
                warning (OPT_Wshadow, 
                         DECL_BUILT_IN (olddecl)
                         ? G_("shadowing built-in function %q#D")
                         : G_("shadowing library function %q#D"), olddecl);
            }
          else
            /* Discard the old built-in function.  */
            return NULL_TREE;

          /* Replace the old RTL to avoid problems with inlining.  */
          COPY_DECL_RTL (newdecl, olddecl);
        }
      /* Even if the types match, prefer the new declarations type for
         built-ins which have not been explicitly declared, for
         exception lists, etc...  */
      else if (DECL_IS_BUILTIN (olddecl))
        {
          tree type = TREE_TYPE (newdecl);
          tree attribs = (*targetm.merge_type_attributes)
            (TREE_TYPE (olddecl), type);

          type = cp_build_type_attribute_variant (type, attribs);
          TREE_TYPE (newdecl) = TREE_TYPE (olddecl) = type;
        }

      /* If a function is explicitly declared "throw ()", propagate that to
         the corresponding builtin.  */
      if (DECL_BUILT_IN_CLASS (olddecl) == BUILT_IN_NORMAL
          && DECL_ANTICIPATED (olddecl)
          && TREE_NOTHROW (newdecl)
          && !TREE_NOTHROW (olddecl)
          && built_in_decls [DECL_FUNCTION_CODE (olddecl)] != NULL_TREE
          && built_in_decls [DECL_FUNCTION_CODE (olddecl)] != olddecl
          && types_match)
        TREE_NOTHROW (built_in_decls [DECL_FUNCTION_CODE (olddecl)]) = 1;

      /* Whether or not the builtin can throw exceptions has no
         bearing on this declarator.  */
      TREE_NOTHROW (olddecl) = 0;

      if (DECL_THIS_STATIC (newdecl) && !DECL_THIS_STATIC (olddecl))
        {
          /* If a builtin function is redeclared as `static', merge
             the declarations, but make the original one static.  */
          DECL_THIS_STATIC (olddecl) = 1;
          TREE_PUBLIC (olddecl) = 0;

          /* Make the old declaration consistent with the new one so
             that all remnants of the builtin-ness of this function
             will be banished.  */
          SET_DECL_LANGUAGE (olddecl, DECL_LANGUAGE (newdecl));
          COPY_DECL_RTL (newdecl, olddecl);
        }
    }
  else if (TREE_CODE (olddecl) != TREE_CODE (newdecl))
    {
      /* C++ Standard, 3.3, clause 4:
         "[Note: a namespace name or a class template name must be unique
         in its declarative region (7.3.2, clause 14). ]"  */
      if (TREE_CODE (olddecl) != NAMESPACE_DECL
          && TREE_CODE (newdecl) != NAMESPACE_DECL
          && (TREE_CODE (olddecl) != TEMPLATE_DECL
              || TREE_CODE (DECL_TEMPLATE_RESULT (olddecl)) != TYPE_DECL)
          && (TREE_CODE (newdecl) != TEMPLATE_DECL
              || TREE_CODE (DECL_TEMPLATE_RESULT (newdecl)) != TYPE_DECL))
        {
          if ((TREE_CODE (olddecl) == TYPE_DECL && DECL_ARTIFICIAL (olddecl)
               && TREE_CODE (newdecl) != TYPE_DECL)
              || (TREE_CODE (newdecl) == TYPE_DECL && DECL_ARTIFICIAL (newdecl)
                  && TREE_CODE (olddecl) != TYPE_DECL))
            {
              /* We do nothing special here, because C++ does such nasty
                 things with TYPE_DECLs.  Instead, just let the TYPE_DECL
                 get shadowed, and know that if we need to find a TYPE_DECL
                 for a given name, we can look in the IDENTIFIER_TYPE_VALUE
                 slot of the identifier.  */
              return NULL_TREE;
            }
            
            if ((TREE_CODE (newdecl) == FUNCTION_DECL
                 && DECL_FUNCTION_TEMPLATE_P (olddecl))
                || (TREE_CODE (olddecl) == FUNCTION_DECL
                    && DECL_FUNCTION_TEMPLATE_P (newdecl)))
              return NULL_TREE;
        }

      error ("%q#D redeclared as different kind of symbol", newdecl);
      if (TREE_CODE (olddecl) == TREE_LIST)
        olddecl = TREE_VALUE (olddecl);
      error ("previous declaration of %q+#D", olddecl);

      return error_mark_node;
    }
  else if (!types_match)
    {
      if (CP_DECL_CONTEXT (newdecl) != CP_DECL_CONTEXT (olddecl))
        /* These are certainly not duplicate declarations; they're
           from different scopes.  */
        return NULL_TREE;

      if (TREE_CODE (newdecl) == TEMPLATE_DECL)
        {
          /* The name of a class template may not be declared to refer to
             any other template, class, function, object, namespace, value,
             or type in the same scope.  */
          if (TREE_CODE (DECL_TEMPLATE_RESULT (olddecl)) == TYPE_DECL
              || TREE_CODE (DECL_TEMPLATE_RESULT (newdecl)) == TYPE_DECL)
            {
              error ("declaration of template %q#D", newdecl);
              error ("conflicts with previous declaration %q+#D", olddecl);
            }
          else if (TREE_CODE (DECL_TEMPLATE_RESULT (olddecl)) == FUNCTION_DECL
                   && TREE_CODE (DECL_TEMPLATE_RESULT (newdecl)) == FUNCTION_DECL
                   && compparms (TYPE_ARG_TYPES (TREE_TYPE (DECL_TEMPLATE_RESULT (olddecl))),
                                 TYPE_ARG_TYPES (TREE_TYPE (DECL_TEMPLATE_RESULT (newdecl))))
                   && comp_template_parms (DECL_TEMPLATE_PARMS (newdecl),
                                           DECL_TEMPLATE_PARMS (olddecl))
                   /* Template functions can be disambiguated by
                      return type.  */
                   && same_type_p (TREE_TYPE (TREE_TYPE (newdecl)),
                                   TREE_TYPE (TREE_TYPE (olddecl))))
            {
              error ("new declaration %q#D", newdecl);
              error ("ambiguates old declaration %q+#D", olddecl);
            }
          return NULL_TREE;
        }
      if (TREE_CODE (newdecl) == FUNCTION_DECL)
        {
          if (DECL_EXTERN_C_P (newdecl) && DECL_EXTERN_C_P (olddecl))
            {
              error ("declaration of C function %q#D conflicts with",
                     newdecl);
              error ("previous declaration %q+#D here", olddecl);
            }
          else if (compparms (TYPE_ARG_TYPES (TREE_TYPE (newdecl)),
                              TYPE_ARG_TYPES (TREE_TYPE (olddecl))))
            {
              error ("new declaration %q#D", newdecl);
              error ("ambiguates old declaration %q+#D", olddecl);
              return error_mark_node;
            }
          else
            return NULL_TREE;
        }
      else
        {
          error ("conflicting declaration %q#D", newdecl);
          error ("%q+D has a previous declaration as %q#D", olddecl, olddecl);
          return error_mark_node;
        }
    }
  else if (TREE_CODE (newdecl) == FUNCTION_DECL
            && ((DECL_TEMPLATE_SPECIALIZATION (olddecl)
                 && (!DECL_TEMPLATE_INFO (newdecl)
                     || (DECL_TI_TEMPLATE (newdecl)
                         != DECL_TI_TEMPLATE (olddecl))))
                || (DECL_TEMPLATE_SPECIALIZATION (newdecl)
                    && (!DECL_TEMPLATE_INFO (olddecl)
                        || (DECL_TI_TEMPLATE (olddecl)
                            != DECL_TI_TEMPLATE (newdecl))))))
    /* It's OK to have a template specialization and a non-template
       with the same type, or to have specializations of two
       different templates with the same type.  Note that if one is a
       specialization, and the other is an instantiation of the same
       template, that we do not exit at this point.  That situation
       can occur if we instantiate a template class, and then
       specialize one of its methods.  This situation is valid, but
       the declarations must be merged in the usual way.  */
    return NULL_TREE;
  else if (TREE_CODE (newdecl) == FUNCTION_DECL
           && ((DECL_TEMPLATE_INSTANTIATION (olddecl)
                && !DECL_USE_TEMPLATE (newdecl))
               || (DECL_TEMPLATE_INSTANTIATION (newdecl)
                   && !DECL_USE_TEMPLATE (olddecl))))
    /* One of the declarations is a template instantiation, and the
       other is not a template at all.  That's OK.  */
    return NULL_TREE;
  else if (TREE_CODE (newdecl) == NAMESPACE_DECL)
    {
      /* In [namespace.alias] we have:

           In a declarative region, a namespace-alias-definition can be
           used to redefine a namespace-alias declared in that declarative
           region to refer only to the namespace to which it already
           refers.

         Therefore, if we encounter a second alias directive for the same
         alias, we can just ignore the second directive.  */
      if (DECL_NAMESPACE_ALIAS (newdecl)
          && (DECL_NAMESPACE_ALIAS (newdecl)
              == DECL_NAMESPACE_ALIAS (olddecl)))
        return olddecl;
      /* [namespace.alias]

         A namespace-name or namespace-alias shall not be declared as
         the name of any other entity in the same declarative region.
         A namespace-name defined at global scope shall not be
         declared as the name of any other entity in any global scope
         of the program.  */
      error ("declaration of namespace %qD conflicts with", newdecl);
      error ("previous declaration of namespace %q+D here", olddecl);
      return error_mark_node;
    }
  else
    {
      const char *errmsg = redeclaration_error_message (newdecl, olddecl);
      if (errmsg)
        {
          error_at (DECL_SOURCE_LOCATION (newdecl), errmsg, newdecl);
          if (DECL_NAME (olddecl) != NULL_TREE)
            error ((DECL_INITIAL (olddecl) && namespace_bindings_p ())
                         ? "%q+#D previously defined here"
                         : "%q+#D previously declared here", olddecl);
          return error_mark_node;
        }
      else if (TREE_CODE (olddecl) == FUNCTION_DECL
               && DECL_INITIAL (olddecl) != NULL_TREE
               && TYPE_ARG_TYPES (TREE_TYPE (olddecl)) == NULL_TREE
               && TYPE_ARG_TYPES (TREE_TYPE (newdecl)) != NULL_TREE)
        {
          /* Prototype decl follows defn w/o prototype.  */
          warning_at (input_location, 0, "prototype for %q+#D", newdecl);
          warning_at (DECL_SOURCE_LOCATION (olddecl), 0,
                      "follows non-prototype definition here");
        }
      else if ((TREE_CODE (olddecl) == FUNCTION_DECL
                || TREE_CODE (olddecl) == VAR_DECL)
               && DECL_LANGUAGE (newdecl) != DECL_LANGUAGE (olddecl))
        {
          /* [dcl.link]
             If two declarations of the same function or object
             specify different linkage-specifications ..., the program
             is ill-formed.... Except for functions with C++ linkage,
             a function declaration without a linkage specification
             shall not precede the first linkage specification for
             that function.  A function can be declared without a
             linkage specification after an explicit linkage
             specification has been seen; the linkage explicitly
             specified in the earlier declaration is not affected by
             such a function declaration.

             DR 563 raises the question why the restrictions on
             functions should not also apply to objects.  Older
             versions of G++ silently ignore the linkage-specification
             for this example:

               namespace N { 
                 extern int i;
                 extern "C" int i;
               }

             which is clearly wrong.  Therefore, we now treat objects
             like functions.  */
          if (current_lang_depth () == 0)
            {
              /* There is no explicit linkage-specification, so we use
                 the linkage from the previous declaration.  */
              if (!DECL_LANG_SPECIFIC (newdecl))
                retrofit_lang_decl (newdecl);
              SET_DECL_LANGUAGE (newdecl, DECL_LANGUAGE (olddecl));
            }
          else
            {
              error ("previous declaration of %q+#D with %qL linkage",
                     olddecl, DECL_LANGUAGE (olddecl));
              error ("conflicts with new declaration with %qL linkage",
                     DECL_LANGUAGE (newdecl));
            }
        }

      if (DECL_LANG_SPECIFIC (olddecl) && DECL_USE_TEMPLATE (olddecl))
        ;
      else if (TREE_CODE (olddecl) == FUNCTION_DECL)
        {
          tree t1 = TYPE_ARG_TYPES (TREE_TYPE (olddecl));
          tree t2 = TYPE_ARG_TYPES (TREE_TYPE (newdecl));
          int i = 1;

          if (TREE_CODE (TREE_TYPE (newdecl)) == METHOD_TYPE)
            t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2);

          for (; t1 && t1 != void_list_node;
               t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2), i++)
            if (TREE_PURPOSE (t1) && TREE_PURPOSE (t2))
              {
                if (1 == simple_cst_equal (TREE_PURPOSE (t1),
                                           TREE_PURPOSE (t2)))
                  {
                    permerror (input_location, "default argument given for parameter %d of %q#D",
                               i, newdecl);
                    permerror (input_location, "after previous specification in %q+#D", olddecl);
                  }
                else
                  {
                    error ("default argument given for parameter %d of %q#D",
                           i, newdecl);
                    error ("after previous specification in %q+#D",
                                 olddecl);
                  }
              }
        }
    }

  /* Do not merge an implicit typedef with an explicit one.  In:

       class A;
       ...
       typedef class A A __attribute__ ((foo));

     the attribute should apply only to the typedef.  */
  if (TREE_CODE (olddecl) == TYPE_DECL
      && (DECL_IMPLICIT_TYPEDEF_P (olddecl)
          || DECL_IMPLICIT_TYPEDEF_P (newdecl)))
    return NULL_TREE;

  /* If new decl is `static' and an `extern' was seen previously,
     warn about it.  */
  warn_extern_redeclared_static (newdecl, olddecl);

  if (!validate_constexpr_redeclaration (olddecl, newdecl))
    return error_mark_node;

  /* We have committed to returning 1 at this point.  */
  if (TREE_CODE (newdecl) == FUNCTION_DECL)
    {
      /* Now that functions must hold information normally held
         by field decls, there is extra work to do so that
         declaration information does not get destroyed during
         definition.  */
      if (DECL_VINDEX (olddecl))
        DECL_VINDEX (newdecl) = DECL_VINDEX (olddecl);
      if (DECL_CONTEXT (olddecl))
        DECL_CONTEXT (newdecl) = DECL_CONTEXT (olddecl);
      DECL_STATIC_CONSTRUCTOR (newdecl) |= DECL_STATIC_CONSTRUCTOR (olddecl);
      DECL_STATIC_DESTRUCTOR (newdecl) |= DECL_STATIC_DESTRUCTOR (olddecl);
      DECL_PURE_VIRTUAL_P (newdecl) |= DECL_PURE_VIRTUAL_P (olddecl);
      DECL_VIRTUAL_P (newdecl) |= DECL_VIRTUAL_P (olddecl);
      DECL_INVALID_OVERRIDER_P (newdecl) |= DECL_INVALID_OVERRIDER_P (olddecl);
      DECL_THIS_STATIC (newdecl) |= DECL_THIS_STATIC (olddecl);
      if (DECL_OVERLOADED_OPERATOR_P (olddecl) != ERROR_MARK)
        SET_OVERLOADED_OPERATOR_CODE
          (newdecl, DECL_OVERLOADED_OPERATOR_P (olddecl));
      new_defines_function = DECL_INITIAL (newdecl) != NULL_TREE;

      /* Optionally warn about more than one declaration for the same
         name, but don't warn about a function declaration followed by a
         definition.  */
      if (warn_redundant_decls && ! DECL_ARTIFICIAL (olddecl)
          && !(new_defines_function && DECL_INITIAL (olddecl) == NULL_TREE)
          /* Don't warn about extern decl followed by definition.  */
          && !(DECL_EXTERNAL (olddecl) && ! DECL_EXTERNAL (newdecl))
          /* Don't warn about friends, let add_friend take care of it.  */
          && ! (newdecl_is_friend || DECL_FRIEND_P (olddecl)))
        {
          warning (OPT_Wredundant_decls, "redundant redeclaration of %qD in same scope", newdecl);
          warning (OPT_Wredundant_decls, "previous declaration of %q+D", olddecl);
        }

      if (DECL_DELETED_FN (newdecl))
        {
          error ("deleted definition of %qD", newdecl);
          error ("after previous declaration %q+D", olddecl);
        }
    }

  /* Deal with C++: must preserve virtual function table size.  */
  if (TREE_CODE (olddecl) == TYPE_DECL)
    {
      tree newtype = TREE_TYPE (newdecl);
      tree oldtype = TREE_TYPE (olddecl);

      if (newtype != error_mark_node && oldtype != error_mark_node
          && TYPE_LANG_SPECIFIC (newtype) && TYPE_LANG_SPECIFIC (oldtype))
        CLASSTYPE_FRIEND_CLASSES (newtype)
          = CLASSTYPE_FRIEND_CLASSES (oldtype);

      DECL_ORIGINAL_TYPE (newdecl) = DECL_ORIGINAL_TYPE (olddecl);
    }

  /* Copy all the DECL_... slots specified in the new decl
     except for any that we copy here from the old type.  */
  DECL_ATTRIBUTES (newdecl)
    = (*targetm.merge_decl_attributes) (olddecl, newdecl);

  if (TREE_CODE (newdecl) == TEMPLATE_DECL)
    {
      tree old_result;
      tree new_result;
      old_result = DECL_TEMPLATE_RESULT (olddecl);
      new_result = DECL_TEMPLATE_RESULT (newdecl);
      TREE_TYPE (olddecl) = TREE_TYPE (old_result);
      DECL_TEMPLATE_SPECIALIZATIONS (olddecl)
        = chainon (DECL_TEMPLATE_SPECIALIZATIONS (olddecl),
                   DECL_TEMPLATE_SPECIALIZATIONS (newdecl));

      DECL_ATTRIBUTES (old_result)
        = (*targetm.merge_decl_attributes) (old_result, new_result);

      if (DECL_FUNCTION_TEMPLATE_P (newdecl))
        {
          if (GNU_INLINE_P (old_result) != GNU_INLINE_P (new_result)
              && DECL_INITIAL (new_result))
            {
              if (DECL_INITIAL (old_result))
                DECL_UNINLINABLE (old_result) = 1;
              else
                DECL_UNINLINABLE (old_result) = DECL_UNINLINABLE (new_result);
              DECL_EXTERNAL (old_result) = DECL_EXTERNAL (new_result);
              DECL_NOT_REALLY_EXTERN (old_result)
                = DECL_NOT_REALLY_EXTERN (new_result);
              DECL_INTERFACE_KNOWN (old_result)
                = DECL_INTERFACE_KNOWN (new_result);
              DECL_DECLARED_INLINE_P (old_result)
                = DECL_DECLARED_INLINE_P (new_result);
              DECL_DISREGARD_INLINE_LIMITS (old_result)
                |= DECL_DISREGARD_INLINE_LIMITS (new_result);

            }
          else
            {
              DECL_DECLARED_INLINE_P (old_result)
                |= DECL_DECLARED_INLINE_P (new_result);
              DECL_DISREGARD_INLINE_LIMITS (old_result)
                |= DECL_DISREGARD_INLINE_LIMITS (new_result);
              check_redeclaration_exception_specification (newdecl, olddecl);
            }
        }

      /* If the new declaration is a definition, update the file and
         line information on the declaration, and also make
         the old declaration the same definition.  */
      if (DECL_INITIAL (new_result) != NULL_TREE)
        {
          DECL_SOURCE_LOCATION (olddecl)
            = DECL_SOURCE_LOCATION (old_result)
            = DECL_SOURCE_LOCATION (newdecl);
          DECL_INITIAL (old_result) = DECL_INITIAL (new_result);
          if (DECL_FUNCTION_TEMPLATE_P (newdecl))
            {
              tree parm;
              DECL_ARGUMENTS (old_result)
                = DECL_ARGUMENTS (new_result);
              for (parm = DECL_ARGUMENTS (old_result); parm;
                   parm = DECL_CHAIN (parm))
                DECL_CONTEXT (parm) = old_result;
            }
        }

      return olddecl;
    }

  if (types_match)
    {
      /* Automatically handles default parameters.  */
      tree oldtype = TREE_TYPE (olddecl);
      tree newtype;

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

      /* If merge_types produces a non-typedef type, just use the old type.  */
      if (TREE_CODE (newdecl) == TYPE_DECL
          && newtype == DECL_ORIGINAL_TYPE (newdecl))
        newtype = oldtype;

      if (TREE_CODE (newdecl) == VAR_DECL)
        {
          DECL_THIS_EXTERN (newdecl) |= DECL_THIS_EXTERN (olddecl);
          DECL_INITIALIZED_P (newdecl) |= DECL_INITIALIZED_P (olddecl);
          DECL_NONTRIVIALLY_INITIALIZED_P (newdecl)
            |= DECL_NONTRIVIALLY_INITIALIZED_P (olddecl);
          DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (newdecl)
            |= DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (olddecl);

          /* Merge the threadprivate attribute from OLDDECL into NEWDECL.  */
          if (DECL_LANG_SPECIFIC (olddecl)
              && CP_DECL_THREADPRIVATE_P (olddecl))
            {
              /* Allocate a LANG_SPECIFIC structure for NEWDECL, if needed.  */
              if (!DECL_LANG_SPECIFIC (newdecl))
                retrofit_lang_decl (newdecl);

              DECL_TLS_MODEL (newdecl) = DECL_TLS_MODEL (olddecl);
              CP_DECL_THREADPRIVATE_P (newdecl) = 1;
            }
        }

      /* Do this after calling `merge_types' so that default
         parameters don't confuse us.  */
      else if (TREE_CODE (newdecl) == FUNCTION_DECL)
        check_redeclaration_exception_specification (newdecl, olddecl);
      TREE_TYPE (newdecl) = TREE_TYPE (olddecl) = newtype;

      if (TREE_CODE (newdecl) == FUNCTION_DECL)
        check_default_args (newdecl);

      /* Lay the type out, unless already done.  */
      if (! same_type_p (newtype, oldtype)
          && TREE_TYPE (newdecl) != error_mark_node
          && !(processing_template_decl && uses_template_parms (newdecl)))
        layout_type (TREE_TYPE (newdecl));

      if ((TREE_CODE (newdecl) == VAR_DECL
           || TREE_CODE (newdecl) == PARM_DECL
           || TREE_CODE (newdecl) == RESULT_DECL
           || TREE_CODE (newdecl) == FIELD_DECL
           || TREE_CODE (newdecl) == TYPE_DECL)
          && !(processing_template_decl && uses_template_parms (newdecl)))
        layout_decl (newdecl, 0);

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

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

      /* Preserve function specific target and optimization options */
      if (TREE_CODE (newdecl) == FUNCTION_DECL)
        {
          if (DECL_FUNCTION_SPECIFIC_TARGET (olddecl)
              && !DECL_FUNCTION_SPECIFIC_TARGET (newdecl))
            DECL_FUNCTION_SPECIFIC_TARGET (newdecl)
              = DECL_FUNCTION_SPECIFIC_TARGET (olddecl);

          if (DECL_FUNCTION_SPECIFIC_OPTIMIZATION (olddecl)
              && !DECL_FUNCTION_SPECIFIC_OPTIMIZATION (newdecl))
            DECL_FUNCTION_SPECIFIC_OPTIMIZATION (newdecl)
              = DECL_FUNCTION_SPECIFIC_OPTIMIZATION (olddecl);
        }

      /* Merge the initialization information.  */
      if (DECL_INITIAL (newdecl) == NULL_TREE
          && DECL_INITIAL (olddecl) != NULL_TREE)
        {
          DECL_INITIAL (newdecl) = DECL_INITIAL (olddecl);
          DECL_SOURCE_LOCATION (newdecl) = DECL_SOURCE_LOCATION (olddecl);
          if (TREE_CODE (newdecl) == FUNCTION_DECL)
            {
              DECL_SAVED_TREE (newdecl) = DECL_SAVED_TREE (olddecl);
              DECL_STRUCT_FUNCTION (newdecl) = DECL_STRUCT_FUNCTION (olddecl);
            }
        }

      /* 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);

      if (TREE_CODE (newdecl) == FUNCTION_DECL)
        {
          DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (newdecl)
            |= DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (olddecl);
          DECL_NO_LIMIT_STACK (newdecl) |= DECL_NO_LIMIT_STACK (olddecl);
          TREE_THIS_VOLATILE (newdecl) |= TREE_THIS_VOLATILE (olddecl);
          TREE_NOTHROW (newdecl) |= TREE_NOTHROW (olddecl);
          DECL_IS_MALLOC (newdecl) |= DECL_IS_MALLOC (olddecl);
          DECL_IS_OPERATOR_NEW (newdecl) |= DECL_IS_OPERATOR_NEW (olddecl);
          DECL_PURE_P (newdecl) |= DECL_PURE_P (olddecl);
          TREE_READONLY (newdecl) |= TREE_READONLY (olddecl);
          DECL_LOOPING_CONST_OR_PURE_P (newdecl) 
            |= DECL_LOOPING_CONST_OR_PURE_P (olddecl);
          /* Keep the old RTL.  */
          COPY_DECL_RTL (olddecl, newdecl);
        }
      else if (TREE_CODE (newdecl) == VAR_DECL
               && (DECL_SIZE (olddecl) || !DECL_SIZE (newdecl)))
        {
          /* Keep the old RTL.  We cannot keep the old RTL if the old
             declaration was for an incomplete object and the new
             declaration is not since many attributes of the RTL will
             change.  */
          COPY_DECL_RTL (olddecl, newdecl);
        }
    }
  /* If cannot merge, then use the new type and qualifiers,
     and don't preserve the old rtl.  */
  else
    {
      /* Clean out any memory we had of the old declaration.  */
      tree oldstatic = value_member (olddecl, static_aggregates);
      if (oldstatic)
        TREE_VALUE (oldstatic) = error_mark_node;

      TREE_TYPE (olddecl) = TREE_TYPE (newdecl);
      TREE_READONLY (olddecl) = TREE_READONLY (newdecl);
      TREE_THIS_VOLATILE (olddecl) = TREE_THIS_VOLATILE (newdecl);
      TREE_SIDE_EFFECTS (olddecl) = TREE_SIDE_EFFECTS (newdecl);
    }

  /* Merge the storage class information.  */
  merge_weak (newdecl, olddecl);

  if (DECL_ONE_ONLY (olddecl))
    DECL_COMDAT_GROUP (newdecl) = DECL_COMDAT_GROUP (olddecl);

  DECL_DEFER_OUTPUT (newdecl) |= DECL_DEFER_OUTPUT (olddecl);
  TREE_PUBLIC (newdecl) = TREE_PUBLIC (olddecl);
  TREE_STATIC (olddecl) = TREE_STATIC (newdecl) |= TREE_STATIC (olddecl);
  if (! DECL_EXTERNAL (olddecl))
    DECL_EXTERNAL (newdecl) = 0;

  new_template_info = NULL_TREE;
  if (DECL_LANG_SPECIFIC (newdecl) && DECL_LANG_SPECIFIC (olddecl))
    {
      bool new_redefines_gnu_inline = false;

      if (new_defines_function
          && ((DECL_INTERFACE_KNOWN (olddecl)
               && TREE_CODE (olddecl) == FUNCTION_DECL)
              || (TREE_CODE (olddecl) == TEMPLATE_DECL
                  && (TREE_CODE (DECL_TEMPLATE_RESULT (olddecl))
                      == FUNCTION_DECL))))
        {
          tree fn = olddecl;

          if (TREE_CODE (fn) == TEMPLATE_DECL)
            fn = DECL_TEMPLATE_RESULT (olddecl);

          new_redefines_gnu_inline = GNU_INLINE_P (fn) && DECL_INITIAL (fn);
        }

      if (!new_redefines_gnu_inline)
        {
          DECL_INTERFACE_KNOWN (newdecl) |= DECL_INTERFACE_KNOWN (olddecl);
          DECL_NOT_REALLY_EXTERN (newdecl) |= DECL_NOT_REALLY_EXTERN (olddecl);
          DECL_COMDAT (newdecl) |= DECL_COMDAT (olddecl);
        }
      DECL_TEMPLATE_INSTANTIATED (newdecl)
        |= DECL_TEMPLATE_INSTANTIATED (olddecl);
      DECL_ODR_USED (newdecl) |= DECL_ODR_USED (olddecl);

      /* If the OLDDECL is an instantiation and/or specialization,
         then the NEWDECL must be too.  But, it may not yet be marked
         as such if the caller has created NEWDECL, but has not yet
         figured out that it is a redeclaration.  */
      if (!DECL_USE_TEMPLATE (newdecl))
        DECL_USE_TEMPLATE (newdecl) = DECL_USE_TEMPLATE (olddecl);

      /* Don't really know how much of the language-specific
         values we should copy from old to new.  */
      DECL_IN_AGGR_P (newdecl) = DECL_IN_AGGR_P (olddecl);
      DECL_REPO_AVAILABLE_P (newdecl) = DECL_REPO_AVAILABLE_P (olddecl);
      DECL_INITIALIZED_IN_CLASS_P (newdecl)
        |= DECL_INITIALIZED_IN_CLASS_P (olddecl);

      if (LANG_DECL_HAS_MIN (newdecl))
        {
          DECL_LANG_SPECIFIC (newdecl)->u.min.u2 =
            DECL_LANG_SPECIFIC (olddecl)->u.min.u2;
          if (DECL_TEMPLATE_INFO (newdecl))
            new_template_info = DECL_TEMPLATE_INFO (newdecl);
          DECL_TEMPLATE_INFO (newdecl) = DECL_TEMPLATE_INFO (olddecl);
        }
      /* Only functions have these fields.  */
      if (TREE_CODE (newdecl) == FUNCTION_DECL
          || DECL_FUNCTION_TEMPLATE_P (newdecl))
        {
          DECL_NONCONVERTING_P (newdecl) = DECL_NONCONVERTING_P (olddecl);
          olddecl_friend = DECL_FRIEND_P (olddecl);
          hidden_friend = (DECL_ANTICIPATED (olddecl)
                           && DECL_HIDDEN_FRIEND_P (olddecl)
                           && newdecl_is_friend);
          DECL_BEFRIENDING_CLASSES (newdecl)
            = chainon (DECL_BEFRIENDING_CLASSES (newdecl),
                       DECL_BEFRIENDING_CLASSES (olddecl));
          /* DECL_THUNKS is only valid for virtual functions,
             otherwise it is a DECL_FRIEND_CONTEXT.  */
          if (DECL_VIRTUAL_P (newdecl))
            DECL_THUNKS (newdecl) = DECL_THUNKS (olddecl);
        }
      /* Only variables have this field.  */
      else if (TREE_CODE (newdecl) == VAR_DECL
               && VAR_HAD_UNKNOWN_BOUND (olddecl))
        SET_VAR_HAD_UNKNOWN_BOUND (newdecl);
    }

  if (TREE_CODE (newdecl) == FUNCTION_DECL)
    {
      tree parm;

      /* Merge parameter attributes. */
      tree oldarg, newarg;
      for (oldarg = DECL_ARGUMENTS(olddecl), 
               newarg = DECL_ARGUMENTS(newdecl);
           oldarg && newarg;
           oldarg = DECL_CHAIN(oldarg), newarg = DECL_CHAIN(newarg)) {
          DECL_ATTRIBUTES (newarg)
              = (*targetm.merge_decl_attributes) (oldarg, newarg);
          DECL_ATTRIBUTES (oldarg) = DECL_ATTRIBUTES (newarg);
      }
      
      if (DECL_TEMPLATE_INSTANTIATION (olddecl)
          && !DECL_TEMPLATE_INSTANTIATION (newdecl))
        {
          /* If newdecl is not a specialization, then it is not a
             template-related function at all.  And that means that we
             should have exited above, returning 0.  */
          gcc_assert (DECL_TEMPLATE_SPECIALIZATION (newdecl));

          if (DECL_ODR_USED (olddecl))
            /* From [temp.expl.spec]:

               If a template, a member template or the member of a class
               template is explicitly specialized then that
               specialization shall be declared before the first use of
               that specialization that would cause an implicit
               instantiation to take place, in every translation unit in
               which such a use occurs.  */
            error ("explicit specialization of %qD after first use",
                      olddecl);

          SET_DECL_TEMPLATE_SPECIALIZATION (olddecl);

          /* Don't propagate visibility from the template to the
             specialization here.  We'll do that in determine_visibility if
             appropriate.  */
          DECL_VISIBILITY_SPECIFIED (olddecl) = 0;

          /* [temp.expl.spec/14] We don't inline explicit specialization
             just because the primary template says so.  */
        }
      else if (new_defines_function && DECL_INITIAL (olddecl))
        {
          /* Never inline re-defined extern inline functions.
             FIXME: this could be better handled by keeping both
             function as separate declarations.  */
          DECL_UNINLINABLE (newdecl) = 1;
        }
      else
        {
          if (DECL_PENDING_INLINE_INFO (newdecl) == 0)
            DECL_PENDING_INLINE_INFO (newdecl) = DECL_PENDING_INLINE_INFO (olddecl);

          DECL_DECLARED_INLINE_P (newdecl) |= DECL_DECLARED_INLINE_P (olddecl);

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

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

      /* Preserve abstractness on cloned [cd]tors.  */
      DECL_ABSTRACT (newdecl) = DECL_ABSTRACT (olddecl);

      /* Update newdecl's parms to point at olddecl.  */
      for (parm = DECL_ARGUMENTS (newdecl); parm;
           parm = DECL_CHAIN (parm))
        DECL_CONTEXT (parm) = olddecl;

      if (! types_match)
        {
          SET_DECL_LANGUAGE (olddecl, DECL_LANGUAGE (newdecl));
          COPY_DECL_ASSEMBLER_NAME (newdecl, olddecl);
          COPY_DECL_RTL (newdecl, olddecl);
        }
      if (! types_match || new_defines_function)
        {
          /* These need to be copied so that the names are available.
             Note that if the types do match, we'll preserve inline
             info and other bits, but if not, we won't.  */
          DECL_ARGUMENTS (olddecl) = DECL_ARGUMENTS (newdecl);
          DECL_RESULT (olddecl) = DECL_RESULT (newdecl);
        }
      if (new_defines_function)
        /* If defining a function declared with other language
           linkage, use the previously declared language linkage.  */
        SET_DECL_LANGUAGE (newdecl, DECL_LANGUAGE (olddecl));
      else if (types_match)
        {
          /* If redeclaring a builtin function, and not a definition,
             it stays built in.  */
          if (DECL_BUILT_IN (olddecl))
            {
              DECL_BUILT_IN_CLASS (newdecl) = DECL_BUILT_IN_CLASS (olddecl);
              DECL_FUNCTION_CODE (newdecl) = DECL_FUNCTION_CODE (olddecl);
              /* If we're keeping the built-in definition, keep the rtl,
                 regardless of declaration matches.  */
              COPY_DECL_RTL (olddecl, newdecl);
            }

          DECL_RESULT (newdecl) = DECL_RESULT (olddecl);
          /* Don't clear out the arguments if we're just redeclaring a
             function.  */
          if (DECL_ARGUMENTS (olddecl))
            DECL_ARGUMENTS (newdecl) = DECL_ARGUMENTS (olddecl);
        }
    }
  else if (TREE_CODE (newdecl) == NAMESPACE_DECL)
    NAMESPACE_LEVEL (newdecl) = NAMESPACE_LEVEL (olddecl);

  /* Now preserve various other info from the definition.  */
  TREE_ADDRESSABLE (newdecl) = TREE_ADDRESSABLE (olddecl);
  TREE_ASM_WRITTEN (newdecl) = TREE_ASM_WRITTEN (olddecl);
  DECL_COMMON (newdecl) = DECL_COMMON (olddecl);
  COPY_DECL_ASSEMBLER_NAME (olddecl, newdecl);

  /* Warn about conflicting visibility specifications.  */
  if (DECL_VISIBILITY_SPECIFIED (olddecl)
      && DECL_VISIBILITY_SPECIFIED (newdecl)
      && DECL_VISIBILITY (newdecl) != DECL_VISIBILITY (olddecl))
    {
      warning_at (input_location, OPT_Wattributes,
                  "%q+D: visibility attribute ignored because it", newdecl);
      warning_at (DECL_SOURCE_LOCATION (olddecl), OPT_Wattributes,
                  "conflicts with previous declaration here");
    }
  /* Choose the declaration which specified visibility.  */
  if (DECL_VISIBILITY_SPECIFIED (olddecl))
    {
      DECL_VISIBILITY (newdecl) = DECL_VISIBILITY (olddecl);
      DECL_VISIBILITY_SPECIFIED (newdecl) = 1;
    }
  /* Init priority used to be merged from newdecl to olddecl by the memcpy,
     so keep this behavior.  */
  if (TREE_CODE (newdecl) == VAR_DECL && DECL_HAS_INIT_PRIORITY_P (newdecl))
    {
      SET_DECL_INIT_PRIORITY (olddecl, DECL_INIT_PRIORITY (newdecl));
      DECL_HAS_INIT_PRIORITY_P (olddecl) = 1;
    }
  /* Likewise for DECL_USER_ALIGN and DECL_PACKED.  */
  DECL_USER_ALIGN (olddecl) = DECL_USER_ALIGN (newdecl);
  if (TREE_CODE (newdecl) == FIELD_DECL)
    DECL_PACKED (olddecl) = DECL_PACKED (newdecl);

  /* The DECL_LANG_SPECIFIC information in OLDDECL will be replaced
     with that from NEWDECL below.  */
  if (DECL_LANG_SPECIFIC (olddecl))
    {
      gcc_assert (DECL_LANG_SPECIFIC (olddecl)
                  != DECL_LANG_SPECIFIC (newdecl));
      ggc_free (DECL_LANG_SPECIFIC (olddecl));
    }

  /* Merge the USED information.  */
  if (TREE_USED (olddecl))
    TREE_USED (newdecl) = 1;
  else if (TREE_USED (newdecl))
    TREE_USED (olddecl) = 1;
  if (TREE_CODE (newdecl) == VAR_DECL)
    {
      if (DECL_READ_P (olddecl))
        DECL_READ_P (newdecl) = 1;
      else if (DECL_READ_P (newdecl))
        DECL_READ_P (olddecl) = 1;
    }
  if (DECL_PRESERVE_P (olddecl))
    DECL_PRESERVE_P (newdecl) = 1;
  else if (DECL_PRESERVE_P (newdecl))
    DECL_PRESERVE_P (olddecl) = 1;

  if (TREE_CODE (newdecl) == FUNCTION_DECL)
    {
      int function_size;

      function_size = sizeof (struct tree_decl_common);

      memcpy ((char *) olddecl + sizeof (struct tree_common),
              (char *) newdecl + sizeof (struct tree_common),
              function_size - sizeof (struct tree_common));

      memcpy ((char *) olddecl + sizeof (struct tree_decl_common),
              (char *) newdecl + sizeof (struct tree_decl_common),
              sizeof (struct tree_function_decl) - sizeof (struct tree_decl_common));
      if (new_template_info)
        /* If newdecl is a template instantiation, it is possible that
           the following sequence of events has occurred:

           o A friend function was declared in a class template.  The
           class template was instantiated.

           o The instantiation of the friend declaration was
           recorded on the instantiation list, and is newdecl.

           o Later, however, instantiate_class_template called pushdecl
           on the newdecl to perform name injection.  But, pushdecl in
           turn called duplicate_decls when it discovered that another
           declaration of a global function with the same name already
           existed.

           o Here, in duplicate_decls, we decided to clobber newdecl.

           If we're going to do that, we'd better make sure that
           olddecl, and not newdecl, is on the list of
           instantiations so that if we try to do the instantiation
           again we won't get the clobbered declaration.  */
        reregister_specialization (newdecl,
                                   new_template_info,
                                   olddecl);
    }
  else
    {
      size_t size = tree_code_size (TREE_CODE (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 LABEL_DECL:
        case VAR_DECL:
        case RESULT_DECL:
        case PARM_DECL:
        case FIELD_DECL:
        case TYPE_DECL:
        case CONST_DECL:
          {
            memcpy ((char *) olddecl + sizeof (struct tree_decl_common),
                    (char *) newdecl + sizeof (struct tree_decl_common),
                    size - sizeof (struct tree_decl_common)
                    + TREE_CODE_LENGTH (TREE_CODE (newdecl)) * sizeof (char *));
          }
          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)
                  + TREE_CODE_LENGTH (TREE_CODE (newdecl)) * sizeof (char *));
          break;
        }
    }
  DECL_UID (olddecl) = olddecl_uid;
  if (olddecl_friend)
    DECL_FRIEND_P (olddecl) = 1;
  if (hidden_friend)
    {
      DECL_ANTICIPATED (olddecl) = 1;
      DECL_HIDDEN_FRIEND_P (olddecl) = 1;
    }

  /* NEWDECL contains the merged attribute lists.
     Update OLDDECL to be the same.  */
  DECL_ATTRIBUTES (olddecl) = DECL_ATTRIBUTES (newdecl);

  /* 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);

  /* The NEWDECL will no longer be needed.  Because every out-of-class
     declaration of a member results in a call to duplicate_decls,
     freeing these nodes represents in a significant savings.  */
  ggc_free (newdecl);

  return olddecl;
}
\f
/* Return zero if the declaration NEWDECL is valid
   when the declaration OLDDECL (assumed to be for the same name)
   has already been seen.
   Otherwise return an error message format string with a %s
   where the identifier should go.  */

static const char *
redeclaration_error_message (tree newdecl, tree olddecl)
{
  if (TREE_CODE (newdecl) == TYPE_DECL)
    {
      /* Because C++ can put things into name space for free,
         constructs like "typedef struct foo { ... } foo"
         would look like an erroneous redeclaration.  */
      if (same_type_p (TREE_TYPE (newdecl), TREE_TYPE (olddecl)))
        return NULL;
      else
        return G_("redefinition of %q#D");
    }
  else if (TREE_CODE (newdecl) == FUNCTION_DECL)
    {
      /* If this is a pure function, its olddecl will actually be
         the original initialization to `0' (which we force to call
         abort()).  Don't complain about redefinition in this case.  */
      if (DECL_LANG_SPECIFIC (olddecl) && DECL_PURE_VIRTUAL_P (olddecl)
          && DECL_INITIAL (olddecl) == NULL_TREE)
        return NULL;

      /* If both functions come from different namespaces, this is not
         a redeclaration - this is a conflict with a used function.  */
      if (DECL_NAMESPACE_SCOPE_P (olddecl)
          && DECL_CONTEXT (olddecl) != DECL_CONTEXT (newdecl)
          && ! decls_match (olddecl, newdecl))
        return G_("%qD conflicts with used function");

      /* We'll complain about linkage mismatches in
         warn_extern_redeclared_static.  */

      /* Defining the same name twice is no good.  */
      if (DECL_INITIAL (olddecl) != NULL_TREE
          && DECL_INITIAL (newdecl) != NULL_TREE)
        {
          if (DECL_NAME (olddecl) == NULL_TREE)
            return G_("%q#D not declared in class");
          else if (!GNU_INLINE_P (olddecl)
                   || GNU_INLINE_P (newdecl))
            return G_("redefinition of %q#D");
        }

      if (DECL_DECLARED_INLINE_P (olddecl) && DECL_DECLARED_INLINE_P (newdecl))
        {
          bool olda = GNU_INLINE_P (olddecl);
          bool newa = GNU_INLINE_P (newdecl);

          if (olda != newa)
            {
              if (newa)
                return G_("%q+D redeclared inline with "
                          "%<gnu_inline%> attribute");
              else
                return G_("%q+D redeclared inline without "
                          "%<gnu_inline%> attribute");
            }
        }

      return NULL;
    }
  else if (TREE_CODE (newdecl) == TEMPLATE_DECL)
    {
      tree nt, ot;

      if (TREE_CODE (DECL_TEMPLATE_RESULT (newdecl)) == TYPE_DECL)
        {
          if (COMPLETE_TYPE_P (TREE_TYPE (newdecl))
              && COMPLETE_TYPE_P (TREE_TYPE (olddecl)))
            return G_("redefinition of %q#D");
          return NULL;
        }

      if (TREE_CODE (DECL_TEMPLATE_RESULT (newdecl)) != FUNCTION_DECL
          || (DECL_TEMPLATE_RESULT (newdecl)
              == DECL_TEMPLATE_RESULT (olddecl)))
        return NULL;

      nt = DECL_TEMPLATE_RESULT (newdecl);
      if (DECL_TEMPLATE_INFO (nt))
        nt = DECL_TEMPLATE_RESULT (template_for_substitution (nt));
      ot = DECL_TEMPLATE_RESULT (olddecl);
      if (DECL_TEMPLATE_INFO (ot))
        ot = DECL_TEMPLATE_RESULT (template_for_substitution (ot));
      if (DECL_INITIAL (nt) && DECL_INITIAL (ot)
          && (!GNU_INLINE_P (ot) || GNU_INLINE_P (nt)))
        return G_("redefinition of %q#D");

      if (DECL_DECLARED_INLINE_P (ot) && DECL_DECLARED_INLINE_P (nt))
        {
          bool olda = GNU_INLINE_P (ot);
          bool newa = GNU_INLINE_P (nt);

          if (olda != newa)
            {
              if (newa)
                return G_("%q+D redeclared inline with "
                          "%<gnu_inline%> attribute");
              else
                return G_("%q+D redeclared inline without "
                          "%<gnu_inline%> attribute");
            }
        }

      /* Core issue #226 (C++0x): 
           
           If a friend function template declaration specifies a
           default template-argument, that declaration shall be a
           definition and shall be the only declaration of the
           function template in the translation unit.  */
      if ((cxx_dialect != cxx98) 
          && TREE_CODE (ot) == FUNCTION_DECL && DECL_FRIEND_P (ot)
          && !check_default_tmpl_args (nt, DECL_TEMPLATE_PARMS (newdecl), 
                                       /*is_primary=*/1, /*is_partial=*/0,
                                       /*is_friend_decl=*/2))
        return G_("redeclaration of friend %q#D "
                  "may not have default template arguments");

      return NULL;
    }
  else if (TREE_CODE (newdecl) == VAR_DECL
           && DECL_THREAD_LOCAL_P (newdecl) != DECL_THREAD_LOCAL_P (olddecl)
           && (! DECL_LANG_SPECIFIC (olddecl)
               || ! CP_DECL_THREADPRIVATE_P (olddecl)
               || DECL_THREAD_LOCAL_P (newdecl)))
    {
      /* Only variables can be thread-local, and all declarations must
         agree on this property.  */
      if (DECL_THREAD_LOCAL_P (newdecl))
        return G_("thread-local declaration of %q#D follows "
                  "non-thread-local declaration");
      else
        return G_("non-thread-local declaration of %q#D follows "
                  "thread-local declaration");
    }
  else if (toplevel_bindings_p () || DECL_NAMESPACE_SCOPE_P (newdecl))
    {
      /* The objects have been declared at namespace scope.  If either
         is a member of an anonymous union, then this is an invalid
         redeclaration.  For example:

           int i;
           union { int i; };

           is invalid.  */
      if ((TREE_CODE (newdecl) == VAR_DECL && DECL_ANON_UNION_VAR_P (newdecl))
          || (TREE_CODE (olddecl) == VAR_DECL && DECL_ANON_UNION_VAR_P (olddecl)))
        return G_("redeclaration of %q#D");
      /* If at least one declaration is a reference, there is no
         conflict.  For example:

           int i = 3;
           extern int i;

         is valid.  */
      if (DECL_EXTERNAL (newdecl) || DECL_EXTERNAL (olddecl))
        return NULL;
      /* Reject two definitions.  */
      return G_("redefinition of %q#D");
    }
  else
    {
      /* Objects declared with block scope:  */
      /* Reject two definitions, and reject a definition
         together with an external reference.  */
      if (!(DECL_EXTERNAL (newdecl) && DECL_EXTERNAL (olddecl)))
        return G_("redeclaration of %q#D");
      return NULL;
    }
}
\f
/* Hash and equality functions for the named_label table.  */

static hashval_t
named_label_entry_hash (const void *data)
{
  const struct named_label_entry *ent = (const struct named_label_entry *) data;
  return DECL_UID (ent->label_decl);
}

static int
named_label_entry_eq (const void *a, const void *b)
{
  const struct named_label_entry *ent_a = (const struct named_label_entry *) a;
  const struct named_label_entry *ent_b = (const struct named_label_entry *) b;
  return ent_a->label_decl == ent_b->label_decl;
}

/* Create a new label, named ID.  */

static tree
make_label_decl (tree id, int local_p)
{
  struct named_label_entry *ent;
  void **slot;
  tree decl;

  decl = build_decl (input_location, LABEL_DECL, id, void_type_node);

  DECL_CONTEXT (decl) = current_function_decl;
  DECL_MODE (decl) = VOIDmode;
  C_DECLARED_LABEL_FLAG (decl) = local_p;

  /* Say where one reference is to the label, for the sake of the
     error if it is not defined.  */
  DECL_SOURCE_LOCATION (decl) = input_location;

  /* Record the fact that this identifier is bound to this label.  */
  SET_IDENTIFIER_LABEL_VALUE (id, decl);

  /* Create the label htab for the function on demand.  */
  if (!named_labels)
    named_labels = htab_create_ggc (13, named_label_entry_hash,
                                    named_label_entry_eq, NULL);

  /* Record this label on the list of labels used in this function.
     We do this before calling make_label_decl so that we get the
     IDENTIFIER_LABEL_VALUE before the new label is declared.  */
  ent = ggc_alloc_cleared_named_label_entry ();
  ent->label_decl = decl;

  slot = htab_find_slot (named_labels, ent, INSERT);
  gcc_assert (*slot == NULL);
  *slot = ent;

  return decl;
}

/* Look for a label named ID in the current function.  If one cannot
   be found, create one.  (We keep track of used, but undefined,
   labels, and complain about them at the end of a function.)  */

tree
lookup_label (tree id)
{
  tree decl;

  timevar_push (TV_NAME_LOOKUP);
  /* You can't use labels at global scope.  */
  if (current_function_decl == NULL_TREE)
    {
      error ("label %qE referenced outside of any function", id);
      POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, NULL_TREE);
    }

  /* See if we've already got this label.  */
  decl = IDENTIFIER_LABEL_VALUE (id);
  if (decl != NULL_TREE && DECL_CONTEXT (decl) == current_function_decl)
    POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, decl);

  decl = make_label_decl (id, /*local_p=*/0);
  POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, decl);
}

/* Declare a local label named ID.  */

tree
declare_local_label (tree id)
{
  tree decl;
  cp_label_binding *bind;

  /* Add a new entry to the SHADOWED_LABELS list so that when we leave
     this scope we can restore the old value of IDENTIFIER_TYPE_VALUE.  */
  bind = VEC_safe_push (cp_label_binding, gc,
                        current_binding_level->shadowed_labels, NULL);
  bind->prev_value = IDENTIFIER_LABEL_VALUE (id);

  decl = make_label_decl (id, /*local_p=*/1);
  bind->label = decl;

  return decl;
}

/* Returns nonzero if it is ill-formed to jump past the declaration of
   DECL.  Returns 2 if it's also a real problem.  */

static int
decl_jump_unsafe (tree decl)
{
  /* [stmt.dcl]/3: A program that jumps from a point where a local variable
     with automatic storage duration is not in scope to a point where it is
     in scope is ill-formed unless the variable has scalar type, class type
     with a trivial default constructor and a trivial destructor, a
     cv-qualified version of one of these types, or an array of one of the
     preceding types and is declared without an initializer (8.5).  */
  tree type = TREE_TYPE (decl);

  if (TREE_CODE (decl) != VAR_DECL || TREE_STATIC (decl)
      || type == error_mark_node)
    return 0;

  type = strip_array_types (type);

  if (type_has_nontrivial_default_init (TREE_TYPE (decl))
      || DECL_NONTRIVIALLY_INITIALIZED_P (decl))
    return 2;

  if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (decl)))
    return 1;

  return 0;
}

/* A subroutine of check_previous_goto_1 to identify a branch to the user.  */

static void
identify_goto (tree decl, const location_t *locus)
{
  if (decl)
    permerror (input_location, "jump to label %qD", decl);
  else
    permerror (input_location, "jump to case label");
  if (locus)
    permerror (*locus, "  from here");
}

/* Check that a single previously seen jump to a newly defined label
   is OK.  DECL is the LABEL_DECL or 0; LEVEL is the binding_level for
   the jump context; NAMES are the names in scope in LEVEL at the jump
   context; LOCUS is the source position of the jump or 0.  Returns
   true if all is well.  */

static bool
check_previous_goto_1 (tree decl, struct cp_binding_level* level, tree names,
                       bool exited_omp, const location_t *locus)
{
  struct cp_binding_level *b;
  bool identified = false, saw_eh = false, saw_omp = false;

  if (exited_omp)
    {
      identify_goto (decl, locus);
      error ("  exits OpenMP structured block");
      identified = saw_omp = true;
    }

  for (b = current_binding_level; b ; b = b->level_chain)
    {
      tree new_decls, old_decls = (b == level ? names : NULL_TREE);

      for (new_decls = b->names; new_decls != old_decls;
           new_decls = DECL_CHAIN (new_decls))
        {
          int problem = decl_jump_unsafe (new_decls);
          if (! problem)
            continue;

          if (!identified)
            {
              identify_goto (decl, locus);
              identified = true;
            }
          if (problem > 1)
            error ("  crosses initialization of %q+#D", new_decls);
          else
            permerror (input_location, "  enters scope of %q+#D which has "
                       "non-trivial destructor", new_decls);
        }

      if (b == level)
        break;
      if ((b->kind == sk_try || b->kind == sk_catch) && !saw_eh)
        {
          if (!identified)
            {
              identify_goto (decl, locus);
              identified = true;
            }
          if (b->kind == sk_try)
            error ("  enters try block");
          else
            error ("  enters catch block");
          saw_eh = true;
        }
      if (b->kind == sk_omp && !saw_omp)
        {
          if (!identified)
            {
              identify_goto (decl, locus);
              identified = true;
            }
          error ("  enters OpenMP structured block");
          saw_omp = true;
        }
    }

  return !identified;
}

static void
check_previous_goto (tree decl, struct named_label_use_entry *use)
{
  check_previous_goto_1 (decl, use->binding_level,
                         use->names_in_scope, use->in_omp_scope,
                         &use->o_goto_locus);
}

static bool
check_switch_goto (struct cp_binding_level* level)
{
  return check_previous_goto_1 (NULL_TREE, level, level->names, false, NULL);
}

/* Check that a new jump to a label DECL is OK.  Called by
   finish_goto_stmt.  */

void
check_goto (tree decl)
{
  struct named_label_entry *ent, dummy;
  bool saw_catch = false, identified = false;
  tree bad;
  unsigned ix;

  /* We can't know where a computed goto is jumping.
     So we assume that it's OK.  */
  if (TREE_CODE (decl) != LABEL_DECL)
    return;

  /* We didn't record any information about this label when we created it,
     and there's not much point since it's trivial to analyze as a return.  */
  if (decl == cdtor_label)
    return;

  dummy.label_decl = decl;
  ent = (struct named_label_entry *) htab_find (named_labels, &dummy);
  gcc_assert (ent != NULL);

  /* If the label hasn't been defined yet, defer checking.  */
  if (! DECL_INITIAL (decl))
    {
      struct named_label_use_entry *new_use;

      /* Don't bother creating another use if the last goto had the
         same data, and will therefore create the same set of errors.  */
      if (ent->uses
          && ent->uses->names_in_scope == current_binding_level->names)
        return;

      new_use = ggc_alloc_named_label_use_entry ();
      new_use->binding_level = current_binding_level;
      new_use->names_in_scope = current_binding_level->names;
      new_use->o_goto_locus = input_location;
      new_use->in_omp_scope = false;

      new_use->next = ent->uses;
      ent->uses = new_use;
      return;
    }

  if (ent->in_try_scope || ent->in_catch_scope
      || ent->in_omp_scope || !VEC_empty (tree, ent->bad_decls))
    {
      permerror (input_location, "jump to label %q+D", decl);
      permerror (input_location, "  from here");
      identified = true;
    }

  FOR_EACH_VEC_ELT (tree, ent->bad_decls, ix, bad)
    {
      int u = decl_jump_unsafe (bad);

      if (u > 1 && DECL_ARTIFICIAL (bad))
        {
          /* Can't skip init of __exception_info.  */
          error_at (DECL_SOURCE_LOCATION (bad), "  enters catch block");
          saw_catch = true;
        }
      else if (u > 1)
        error ("  skips initialization of %q+#D", bad);
      else
        permerror (input_location, "  enters scope of %q+#D which has "
                   "non-trivial destructor", bad);
    }

  if (ent->in_try_scope)
    error ("  enters try block");
  else if (ent->in_catch_scope && !saw_catch)
    error ("  enters catch block");

  if (ent->in_omp_scope)
    error ("  enters OpenMP structured block");
  else if (flag_openmp)
    {
      struct cp_binding_level *b;
      for (b = current_binding_level; b ; b = b->level_chain)
        {
          if (b == ent->binding_level)
            break;
          if (b->kind == sk_omp)
            {
              if (!identified)
                {
                  permerror (input_location, "jump to label %q+D", decl);
                  permerror (input_location, "  from here");
                  identified = true;
                }
              error ("  exits OpenMP structured block");
              break;
            }
        }
    }
}

/* Check that a return is ok wrt OpenMP structured blocks.
   Called by finish_return_stmt.  Returns true if all is well.  */

bool
check_omp_return (void)
{
  struct cp_binding_level *b;
  for (b = current_binding_level; b ; b = b->level_chain)
    if (b->kind == sk_omp)
      {
        error ("invalid exit from OpenMP structured block");
        return false;
      }
  return true;
}

/* Define a label, specifying the location in the source file.
   Return the LABEL_DECL node for the label.  */

tree
define_label (location_t location, tree name)
{
  struct named_label_entry *ent, dummy;
  struct cp_binding_level *p;
  tree decl;

  timevar_push (TV_NAME_LOOKUP);

  decl = lookup_label (name);

  dummy.label_decl = decl;
  ent = (struct named_label_entry *) htab_find (named_labels, &dummy);
  gcc_assert (ent != NULL);

  /* After labels, make any new cleanups in the function go into their
     own new (temporary) binding contour.  */
  for (p = current_binding_level;
       p->kind != sk_function_parms;
       p = p->level_chain)
    p->more_cleanups_ok = 0;

  if (name == get_identifier ("wchar_t"))
    permerror (input_location, "label named wchar_t");

  if (DECL_INITIAL (decl) != NULL_TREE)
    {
      error ("duplicate label %qD", decl);
      POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, error_mark_node);
    }
  else
    {
      struct named_label_use_entry *use;

      /* Mark label as having been defined.  */
      DECL_INITIAL (decl) = error_mark_node;
      /* Say where in the source.  */
      DECL_SOURCE_LOCATION (decl) = location;

      ent->binding_level = current_binding_level;
      ent->names_in_scope = current_binding_level->names;

      for (use = ent->uses; use ; use = use->next)
        check_previous_goto (decl, use);
      ent->uses = NULL;
    }

  POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, decl);
}

struct cp_switch
{
  struct cp_binding_level *level;
  struct cp_switch *next;
  /* The SWITCH_STMT being built.  */
  tree switch_stmt;
  /* A splay-tree mapping the low element of a case range to the high
     element, or NULL_TREE if there is no high element.  Used to
     determine whether or not a new case label duplicates an old case
     label.  We need a tree, rather than simply a hash table, because
     of the GNU case range extension.  */
  splay_tree cases;
};

/* A stack of the currently active switch statements.  The innermost
   switch statement is on the top of the stack.  There is no need to
   mark the stack for garbage collection because it is only active
   during the processing of the body of a function, and we never
   collect at that point.  */

static struct cp_switch *switch_stack;

/* Called right after a switch-statement condition is parsed.
   SWITCH_STMT is the switch statement being parsed.  */

void
push_switch (tree switch_stmt)
{
  struct cp_switch *p = XNEW (struct cp_switch);
  p->level = current_binding_level;
  p->next = switch_stack;
  p->switch_stmt = switch_stmt;
  p->cases = splay_tree_new (case_compare, NULL, NULL);
  switch_stack = p;
}

void
pop_switch (void)
{
  struct cp_switch *cs = switch_stack;
  location_t switch_location;

  /* Emit warnings as needed.  */
  switch_location = EXPR_LOC_OR_HERE (cs->switch_stmt);
  if (!processing_template_decl)
    c_do_switch_warnings (cs->cases, switch_location,
                          SWITCH_STMT_TYPE (cs->switch_stmt),
                          SWITCH_STMT_COND (cs->switch_stmt));

  splay_tree_delete (cs->cases);
  switch_stack = switch_stack->next;
  free (cs);
}

/* Note that we've seen a definition of a case label, and complain if this
   is a bad place for one.  */

tree
finish_case_label (location_t loc, tree low_value, tree high_value)
{
  tree cond, r;
  struct cp_binding_level *p;

  if (processing_template_decl)
    {
      tree label;

      /* For templates, just add the case label; we'll do semantic
         analysis at instantiation-time.  */
      label = build_decl (loc, LABEL_DECL, NULL_TREE, NULL_TREE);
      return add_stmt (build_case_label (loc, low_value, high_value, label));
    }

  /* Find the condition on which this switch statement depends.  */
  cond = SWITCH_STMT_COND (switch_stack->switch_stmt);
  if (cond && TREE_CODE (cond) == TREE_LIST)
    cond = TREE_VALUE (cond);

  if (!check_switch_goto (switch_stack->level))
    return error_mark_node;

  if (low_value)
    low_value = cxx_constant_value (low_value);
  if (high_value)
    high_value = cxx_constant_value (high_value);

  r = c_add_case_label (loc, switch_stack->cases, cond,
                        SWITCH_STMT_TYPE (switch_stack->switch_stmt),
                        low_value, high_value);

  /* After labels, make any new cleanups in the function go into their
     own new (temporary) binding contour.  */
  for (p = current_binding_level;
       p->kind != sk_function_parms;
       p = p->level_chain)
    p->more_cleanups_ok = 0;

  return r;
}
\f
/* Hash a TYPENAME_TYPE.  K is really of type `tree'.  */

static hashval_t
typename_hash (const void* k)
{
  hashval_t hash;
  const_tree const t = (const_tree) k;

  hash = (htab_hash_pointer (TYPE_CONTEXT (t))
          ^ htab_hash_pointer (DECL_NAME (TYPE_NAME (t))));

  return hash;
}

typedef struct typename_info {
  tree scope;
  tree name;
  tree template_id;
  bool enum_p;
  bool class_p;
} typename_info;

/* Compare two TYPENAME_TYPEs.  K1 is really of type `tree', K2 is
   really of type `typename_info*'  */

static int
typename_compare (const void * k1, const void * k2)
{
  const_tree const t1 = (const_tree) k1;
  const typename_info *const t2 = (const typename_info *) k2;

  return (DECL_NAME (TYPE_NAME (t1)) == t2->name
          && TYPE_CONTEXT (t1) == t2->scope
          && TYPENAME_TYPE_FULLNAME (t1) == t2->template_id
          && TYPENAME_IS_ENUM_P (t1) == t2->enum_p
          && TYPENAME_IS_CLASS_P (t1) == t2->class_p);
}

/* Build a TYPENAME_TYPE.  If the type is `typename T::t', CONTEXT is
   the type of `T', NAME is the IDENTIFIER_NODE for `t'.

   Returns the new TYPENAME_TYPE.  */

static GTY ((param_is (union tree_node))) htab_t typename_htab;

static tree
build_typename_type (tree context, tree name, tree fullname,
                     enum tag_types tag_type)
{
  tree t;
  tree d;
  typename_info ti;
  void **e;
  hashval_t hash;

  if (typename_htab == NULL)
    typename_htab = htab_create_ggc (61, &typename_hash,
                                     &typename_compare, NULL);

  ti.scope = FROB_CONTEXT (context);
  ti.name = name;
  ti.template_id = fullname;
  ti.enum_p = tag_type == enum_type;
  ti.class_p = (tag_type == class_type
                || tag_type == record_type
                || tag_type == union_type);
  hash =  (htab_hash_pointer (ti.scope)
           ^ htab_hash_pointer (ti.name));

  /* See if we already have this type.  */
  e = htab_find_slot_with_hash (typename_htab, &ti, hash, INSERT);
  if (*e)
    t = (tree) *e;
  else
    {
      /* Build the TYPENAME_TYPE.  */
      t = cxx_make_type (TYPENAME_TYPE);
      TYPE_CONTEXT (t) = ti.scope;
      TYPENAME_TYPE_FULLNAME (t) = ti.template_id;
      TYPENAME_IS_ENUM_P (t) = ti.enum_p;
      TYPENAME_IS_CLASS_P (t) = ti.class_p;

      /* Build the corresponding TYPE_DECL.  */
      d = build_decl (input_location, TYPE_DECL, name, t);
      TYPE_NAME (TREE_TYPE (d)) = d;
      TYPE_STUB_DECL (TREE_TYPE (d)) = d;
      DECL_CONTEXT (d) = FROB_CONTEXT (context);
      DECL_ARTIFICIAL (d) = 1;

      /* Store it in the hash table.  */
      *e = t;

      /* TYPENAME_TYPEs must always be compared structurally, because
         they may or may not resolve down to another type depending on
         the currently open classes. */
      SET_TYPE_STRUCTURAL_EQUALITY (t);
    }

  return t;
}

/* Resolve `typename CONTEXT::NAME'.  TAG_TYPE indicates the tag
   provided to name the type.  Returns an appropriate type, unless an
   error occurs, in which case error_mark_node is returned.  If we
   locate a non-artificial TYPE_DECL and TF_KEEP_TYPE_DECL is set, we
   return that, rather than the _TYPE it corresponds to, in other
   cases we look through the type decl.  If TF_ERROR is set, complain
   about errors, otherwise be quiet.  */

tree
make_typename_type (tree context, tree name, enum tag_types tag_type,
                    tsubst_flags_t complain)
{
  tree fullname;
  tree t;
  bool want_template;

  if (name == error_mark_node
      || context == NULL_TREE
      || context == error_mark_node)
    return error_mark_node;

  if (TYPE_P (name))
    {
      if (!(TYPE_LANG_SPECIFIC (name)
            && (CLASSTYPE_IS_TEMPLATE (name)
                || CLASSTYPE_USE_TEMPLATE (name))))
        name = TYPE_IDENTIFIER (name);
      else
        /* Create a TEMPLATE_ID_EXPR for the type.  */
        name = build_nt (TEMPLATE_ID_EXPR,
                         CLASSTYPE_TI_TEMPLATE (name),
                         CLASSTYPE_TI_ARGS (name));
    }
  else if (TREE_CODE (name) == TYPE_DECL)
    name = DECL_NAME (name);

  fullname = name;

  if (TREE_CODE (name) == TEMPLATE_ID_EXPR)
    {
      name = TREE_OPERAND (name, 0);
      if (TREE_CODE (name) == TEMPLATE_DECL)
        name = TREE_OPERAND (fullname, 0) = DECL_NAME (name);
      else if (TREE_CODE (name) == OVERLOAD)
        {
          error ("%qD is not a type", name);
          return error_mark_node;
        }
    }
  if (TREE_CODE (name) == TEMPLATE_DECL)
    {
      error ("%qD used without template parameters", name);
      return error_mark_node;
    }
  gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE);
  gcc_assert (TYPE_P (context));

  if (!MAYBE_CLASS_TYPE_P (context))
    {
      if (complain & tf_error)
        error ("%q#T is not a class", context);
      return error_mark_node;
    }
  
  /* When the CONTEXT is a dependent type,  NAME could refer to a
     dependent base class of CONTEXT.  But look inside it anyway
     if CONTEXT is a currently open scope, in case it refers to a
     member of the current instantiation or a non-dependent base;
     lookup will stop when we hit a dependent base.  */
  if (!dependent_scope_p (context))
    /* We should only set WANT_TYPE when we're a nested typename type.
       Then we can give better diagnostics if we find a non-type.  */
    t = lookup_field (context, name, 2, /*want_type=*/true);
  else
    t = NULL_TREE;

  if ((!t || TREE_CODE (t) == TREE_LIST) && dependent_type_p (context))
    return build_typename_type (context, name, fullname, tag_type);

  want_template = TREE_CODE (fullname) == TEMPLATE_ID_EXPR;
  
  if (!t)
    {
      if (complain & tf_error)
        error (want_template ? "no class template named %q#T in %q#T"
               : "no type named %q#T in %q#T", name, context);
      return error_mark_node;
    }
  
  /* Pull out the template from an injected-class-name (or multiple).  */
  if (want_template)
    t = maybe_get_template_decl_from_type_decl (t);

  if (TREE_CODE (t) == TREE_LIST)
    {
      if (complain & tf_error)
        {
          error ("lookup of %qT in %qT is ambiguous", name, context);
          print_candidates (t);
        }
      return error_mark_node;
    }

  if (want_template && !DECL_CLASS_TEMPLATE_P (t))
    {
      if (complain & tf_error)
        error ("%<typename %T::%D%> names %q#T, which is not a class template",
               context, name, t);
      return error_mark_node;
    }
  if (!want_template && TREE_CODE (t) != TYPE_DECL)
    {
      if (complain & tf_error)
        error ("%<typename %T::%D%> names %q#T, which is not a type",
               context, name, t);
      return error_mark_node;
    }
  
  if (complain & tf_error)
    perform_or_defer_access_check (TYPE_BINFO (context), t, t);

  /* If we are currently parsing a template and if T is a typedef accessed
     through CONTEXT then we need to remember and check access of T at
     template instantiation time.  */
  add_typedef_to_current_template_for_access_check (t, context, input_location);

  if (want_template)
    return lookup_template_class (t, TREE_OPERAND (fullname, 1),
                                  NULL_TREE, context,
                                  /*entering_scope=*/0,
                                  tf_warning_or_error | tf_user);
  
  if (DECL_ARTIFICIAL (t) || !(complain & tf_keep_type_decl))
    t = TREE_TYPE (t);
  
  return t;
}

/* Resolve `CONTEXT::template NAME'.  Returns a TEMPLATE_DECL if the name
   can be resolved or an UNBOUND_CLASS_TEMPLATE, unless an error occurs,
   in which case error_mark_node is returned.

   If PARM_LIST is non-NULL, also make sure that the template parameter
   list of TEMPLATE_DECL matches.

   If COMPLAIN zero, don't complain about any errors that occur.  */

tree
make_unbound_class_template (tree context, tree name, tree parm_list,
                             tsubst_flags_t complain)
{
  tree t;
  tree d;

  if (TYPE_P (name))
    name = TYPE_IDENTIFIER (name);
  else if (DECL_P (name))
    name = DECL_NAME (name);
  gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE);

  if (!dependent_type_p (context)
      || currently_open_class (context))
    {
      tree tmpl = NULL_TREE;

      if (MAYBE_CLASS_TYPE_P (context))
        tmpl = lookup_field (context, name, 0, false);

      if (tmpl && TREE_CODE (tmpl) == TYPE_DECL)
        tmpl = maybe_get_template_decl_from_type_decl (tmpl);

      if (!tmpl || !DECL_CLASS_TEMPLATE_P (tmpl))
        {
          if (complain & tf_error)
            error ("no class template named %q#T in %q#T", name, context);
          return error_mark_node;
        }

      if (parm_list
          && !comp_template_parms (DECL_TEMPLATE_PARMS (tmpl), parm_list))
        {
          if (complain & tf_error)
            {
              error ("template parameters do not match template");
              error ("%q+D declared here", tmpl);
            }
          return error_mark_node;
        }

      if (complain & tf_error)
        perform_or_defer_access_check (TYPE_BINFO (context), tmpl, tmpl);

      return tmpl;
    }

  /* Build the UNBOUND_CLASS_TEMPLATE.  */
  t = cxx_make_type (UNBOUND_CLASS_TEMPLATE);
  TYPE_CONTEXT (t) = FROB_CONTEXT (context);
  TREE_TYPE (t) = NULL_TREE;
  SET_TYPE_STRUCTURAL_EQUALITY (t);

  /* Build the corresponding TEMPLATE_DECL.  */
  d = build_decl (input_location, TEMPLATE_DECL, name, t);
  TYPE_NAME (TREE_TYPE (d)) = d;
  TYPE_STUB_DECL (TREE_TYPE (d)) = d;
  DECL_CONTEXT (d) = FROB_CONTEXT (context);
  DECL_ARTIFICIAL (d) = 1;
  DECL_TEMPLATE_PARMS (d) = parm_list;

  return t;
}

\f

/* Push the declarations of builtin types into the namespace.
   RID_INDEX is the index of the builtin type in the array
   RID_POINTERS.  NAME is the name used when looking up the builtin
   type.  TYPE is the _TYPE node for the builtin type.  */

void
record_builtin_type (enum rid rid_index,
                     const char* name,
                     tree type)
{
  tree rname = NULL_TREE, tname = NULL_TREE;
  tree tdecl = NULL_TREE;

  if ((int) rid_index < (int) RID_MAX)
    rname = ridpointers[(int) rid_index];
  if (name)
    tname = get_identifier (name);

  /* The calls to SET_IDENTIFIER_GLOBAL_VALUE below should be
     eliminated.  Built-in types should not be looked up name; their
     names are keywords that the parser can recognize.  However, there
     is code in c-common.c that uses identifier_global_value to look
     up built-in types by name.  */
  if (tname)
    {
      tdecl = build_decl (BUILTINS_LOCATION, TYPE_DECL, tname, type);
      DECL_ARTIFICIAL (tdecl) = 1;
      SET_IDENTIFIER_GLOBAL_VALUE (tname, tdecl);
    }
  if (rname)
    {
      if (!tdecl)
        {
          tdecl = build_decl (BUILTINS_LOCATION, TYPE_DECL, rname, type);
          DECL_ARTIFICIAL (tdecl) = 1;
        }
      SET_IDENTIFIER_GLOBAL_VALUE (rname, tdecl);
    }

  if (!TYPE_NAME (type))
    TYPE_NAME (type) = tdecl;

  if (tdecl)
    debug_hooks->type_decl (tdecl, 0);
}

/* Record one of the standard Java types.
 * Declare it as having the given NAME.
 * If SIZE > 0, it is the size of one of the integral types;
 * otherwise it is the negative of the size of one of the other types.  */

static tree
record_builtin_java_type (const char* name, int size)
{
  tree type, decl;
  if (size > 0)
    type = build_nonstandard_integer_type (size, 0);
  else if (size > -32)
    {
      tree stype;
      /* "__java_char" or ""__java_boolean".  */
      type = build_nonstandard_integer_type (-size, 1);
      /* Get the signed type cached and attached to the unsigned type,
         so it doesn't get garbage-collected at "random" times,
         causing potential codegen differences out of different UIDs
         and different alias set numbers.  */
      stype = build_nonstandard_integer_type (-size, 0);
      TREE_CHAIN (type) = stype;
      /*if (size == -1) TREE_SET_CODE (type, BOOLEAN_TYPE);*/
    }
  else
    { /* "__java_float" or ""__java_double".  */
      type = make_node (REAL_TYPE);
      TYPE_PRECISION (type) = - size;
      layout_type (type);
    }
  record_builtin_type (RID_MAX, name, type);
  decl = TYPE_NAME (type);

  /* Suppress generate debug symbol entries for these types,
     since for normal C++ they are just clutter.
     However, push_lang_context undoes this if extern "Java" is seen.  */
  DECL_IGNORED_P (decl) = 1;

  TYPE_FOR_JAVA (type) = 1;
  return type;
}

/* Push a type into the namespace so that the back ends ignore it.  */

static void
record_unknown_type (tree type, const char* name)
{
  tree decl = pushdecl (build_decl (UNKNOWN_LOCATION,
                                    TYPE_DECL, get_identifier (name), type));
  /* Make sure the "unknown type" typedecl gets ignored for debug info.  */
  DECL_IGNORED_P (decl) = 1;
  TYPE_DECL_SUPPRESS_DEBUG (decl) = 1;
  TYPE_SIZE (type) = TYPE_SIZE (void_type_node);
  TYPE_ALIGN (type) = 1;
  TYPE_USER_ALIGN (type) = 0;
  SET_TYPE_MODE (type, TYPE_MODE (void_type_node));
}

/* A string for which we should create an IDENTIFIER_NODE at
   startup.  */

typedef struct predefined_identifier
{
  /* The name of the identifier.  */
  const char *const name;
  /* The place where the IDENTIFIER_NODE should be stored.  */
  tree *const node;
  /* Nonzero if this is the name of a constructor or destructor.  */
  const int ctor_or_dtor_p;
} predefined_identifier;

/* Create all the predefined identifiers.  */

static void
initialize_predefined_identifiers (void)
{
  const predefined_identifier *pid;

  /* A table of identifiers to create at startup.  */
  static const predefined_identifier predefined_identifiers[] = {
    { "C++", &lang_name_cplusplus, 0 },
    { "C", &lang_name_c, 0 },
    { "Java", &lang_name_java, 0 },
    /* Some of these names have a trailing space so that it is
       impossible for them to conflict with names written by users.  */
    { "__ct ", &ctor_identifier, 1 },
    { "__base_ctor ", &base_ctor_identifier, 1 },
    { "__comp_ctor ", &complete_ctor_identifier, 1 },
    { "__dt ", &dtor_identifier, 1 },
    { "__comp_dtor ", &complete_dtor_identifier, 1 },
    { "__base_dtor ", &base_dtor_identifier, 1 },
    { "__deleting_dtor ", &deleting_dtor_identifier, 1 },
    { IN_CHARGE_NAME, &in_charge_identifier, 0 },
    { "nelts", &nelts_identifier, 0 },
    { THIS_NAME, &this_identifier, 0 },
    { VTABLE_DELTA_NAME, &delta_identifier, 0 },
    { VTABLE_PFN_NAME, &pfn_identifier, 0 },
    { "_vptr", &vptr_identifier, 0 },
    { "__vtt_parm", &vtt_parm_identifier, 0 },
    { "::", &global_scope_name, 0 },
    { "std", &std_identifier, 0 },
    { NULL, NULL, 0 }
  };

  for (pid = predefined_identifiers; pid->name; ++pid)
    {
      *pid->node = get_identifier (pid->name);
      if (pid->ctor_or_dtor_p)
        IDENTIFIER_CTOR_OR_DTOR_P (*pid->node) = 1;
    }
}

/* Create the predefined scalar types of C,
   and some nodes representing standard constants (0, 1, (void *)0).
   Initialize the global binding level.
   Make definitions for built-in primitive functions.  */

void
cxx_init_decl_processing (void)
{
  tree void_ftype;
  tree void_ftype_ptr;

  build_common_tree_nodes (flag_signed_char);

  /* Create all the identifiers we need.  */
  initialize_predefined_identifiers ();

  /* Create the global variables.  */
  push_to_top_level ();

  current_function_decl = NULL_TREE;
  current_binding_level = NULL;
  /* Enter the global namespace.  */
  gcc_assert (global_namespace == NULL_TREE);
  global_namespace = build_lang_decl (NAMESPACE_DECL, global_scope_name,
                                      void_type_node);
  DECL_CONTEXT (global_namespace) = build_translation_unit_decl (NULL_TREE);
  TREE_PUBLIC (global_namespace) = 1;
  begin_scope (sk_namespace, global_namespace);

  current_lang_name = NULL_TREE;

  if (flag_visibility_ms_compat)
    default_visibility = VISIBILITY_HIDDEN;

  /* Initially, C.  */
  current_lang_name = lang_name_c;

  /* Create the `std' namespace.  */
  push_namespace (std_identifier);
  std_node = current_namespace;
  pop_namespace ();

  c_common_nodes_and_builtins ();

  java_byte_type_node = record_builtin_java_type ("__java_byte", 8);
  java_short_type_node = record_builtin_java_type ("__java_short", 16);
  java_int_type_node = record_builtin_java_type ("__java_int", 32);
  java_long_type_node = record_builtin_java_type ("__java_long", 64);
  java_float_type_node = record_builtin_java_type ("__java_float", -32);
  java_double_type_node = record_builtin_java_type ("__java_double", -64);
  java_char_type_node = record_builtin_java_type ("__java_char", -16);
  java_boolean_type_node = record_builtin_java_type ("__java_boolean", -1);

  integer_two_node = build_int_cst (NULL_TREE, 2);

  record_builtin_type (RID_BOOL, "bool", boolean_type_node);
  truthvalue_type_node = boolean_type_node;
  truthvalue_false_node = boolean_false_node;
  truthvalue_true_node = boolean_true_node;

  empty_except_spec = build_tree_list (NULL_TREE, NULL_TREE);
  noexcept_true_spec = build_tree_list (boolean_true_node, NULL_TREE);
  noexcept_false_spec = build_tree_list (boolean_false_node, NULL_TREE);

#if 0
  record_builtin_type (RID_MAX, NULL, string_type_node);
#endif

  delta_type_node = ptrdiff_type_node;
  vtable_index_type = ptrdiff_type_node;

  vtt_parm_type = build_pointer_type (const_ptr_type_node);
  void_ftype = build_function_type_list (void_type_node, NULL_TREE);
  void_ftype_ptr = build_function_type_list (void_type_node,
                                             ptr_type_node, NULL_TREE);
  void_ftype_ptr
    = build_exception_variant (void_ftype_ptr, empty_except_spec);

  /* C++ extensions */

  unknown_type_node = make_node (LANG_TYPE);
  record_unknown_type (unknown_type_node, "unknown type");

  /* Indirecting an UNKNOWN_TYPE node yields an UNKNOWN_TYPE node.  */
  TREE_TYPE (unknown_type_node) = unknown_type_node;

  /* Looking up TYPE_POINTER_TO and TYPE_REFERENCE_TO yield the same
     result.  */
  TYPE_POINTER_TO (unknown_type_node) = unknown_type_node;
  TYPE_REFERENCE_TO (unknown_type_node) = unknown_type_node;

  init_list_type_node = make_node (LANG_TYPE);
  record_unknown_type (init_list_type_node, "init list");

  {
    /* Make sure we get a unique function type, so we can give
       its pointer type a name.  (This wins for gdb.) */
    tree vfunc_type = make_node (FUNCTION_TYPE);
    TREE_TYPE (vfunc_type) = integer_type_node;
    TYPE_ARG_TYPES (vfunc_type) = NULL_TREE;
    layout_type (vfunc_type);

    vtable_entry_type = build_pointer_type (vfunc_type);
  }
  record_builtin_type (RID_MAX, VTBL_PTR_TYPE, vtable_entry_type);

  vtbl_type_node
    = build_cplus_array_type (vtable_entry_type, NULL_TREE);
  layout_type (vtbl_type_node);
  vtbl_type_node = cp_build_qualified_type (vtbl_type_node, TYPE_QUAL_CONST);
  record_builtin_type (RID_MAX, NULL, vtbl_type_node);
  vtbl_ptr_type_node = build_pointer_type (vtable_entry_type);
  layout_type (vtbl_ptr_type_node);
  record_builtin_type (RID_MAX, NULL, vtbl_ptr_type_node);

  push_namespace (get_identifier ("__cxxabiv1"));
  abi_node = current_namespace;
  pop_namespace ();

  global_type_node = make_node (LANG_TYPE);
  record_unknown_type (global_type_node, "global type");

  /* Now, C++.  */
  current_lang_name = lang_name_cplusplus;

  {
    tree newtype, deltype;
    tree ptr_ftype_sizetype;
    tree new_eh_spec;

    ptr_ftype_sizetype
      = build_function_type_list (ptr_type_node, size_type_node, NULL_TREE);
    if (cxx_dialect == cxx98)
      {
        tree bad_alloc_id;
        tree bad_alloc_type_node;
        tree bad_alloc_decl;

        push_namespace (std_identifier);
        bad_alloc_id = get_identifier ("bad_alloc");
        bad_alloc_type_node = make_class_type (RECORD_TYPE);
        TYPE_CONTEXT (bad_alloc_type_node) = current_namespace;
        bad_alloc_decl
          = create_implicit_typedef (bad_alloc_id, bad_alloc_type_node);
        DECL_CONTEXT (bad_alloc_decl) = current_namespace;
        pop_namespace ();

        new_eh_spec
          = add_exception_specifier (NULL_TREE, bad_alloc_type_node, -1);
      }
    else
      new_eh_spec = noexcept_false_spec;

    newtype = build_exception_variant (ptr_ftype_sizetype, new_eh_spec);
    deltype = build_exception_variant (void_ftype_ptr, empty_except_spec);
    push_cp_library_fn (NEW_EXPR, newtype);
    push_cp_library_fn (VEC_NEW_EXPR, newtype);
    global_delete_fndecl = push_cp_library_fn (DELETE_EXPR, deltype);
    push_cp_library_fn (VEC_DELETE_EXPR, deltype);

    nullptr_type_node = make_node (NULLPTR_TYPE);
    TYPE_SIZE (nullptr_type_node) = bitsize_int (GET_MODE_BITSIZE (ptr_mode));
    TYPE_SIZE_UNIT (nullptr_type_node) = size_int (GET_MODE_SIZE (ptr_mode));
    TYPE_UNSIGNED (nullptr_type_node) = 1;
    TYPE_PRECISION (nullptr_type_node) = GET_MODE_BITSIZE (ptr_mode);
    SET_TYPE_MODE (nullptr_type_node, Pmode);
    record_builtin_type (RID_MAX, "decltype(nullptr)", nullptr_type_node);
    nullptr_node = build_int_cst (nullptr_type_node, 0);
  }

  abort_fndecl
    = build_library_fn_ptr ("__cxa_pure_virtual", void_ftype);

  /* Perform other language dependent initializations.  */
  init_class_processing ();
  init_rtti_processing ();
  init_template_processing ();

  if (flag_exceptions)
    init_exception_processing ();

  if (! supports_one_only ())
    flag_weak = 0;

  make_fname_decl = cp_make_fname_decl;
  start_fname_decls ();

  /* Show we use EH for cleanups.  */
  if (flag_exceptions)
    using_eh_for_cleanups ();
}

/* Generate an initializer for a function naming variable from
   NAME. NAME may be NULL, to indicate a dependent name.  TYPE_P is
   filled in with the type of the init.  */

tree
cp_fname_init (const char* name, tree *type_p)
{
  tree domain = NULL_TREE;
  tree type;
  tree init = NULL_TREE;
  size_t length = 0;

  if (name)
    {
      length = strlen (name);
      domain = build_index_type (size_int (length));
      init = build_string (length + 1, name);
    }

  type = cp_build_qualified_type (char_type_node, TYPE_QUAL_CONST);
  type = build_cplus_array_type (type, domain);

  *type_p = type;

  if (init)
    TREE_TYPE (init) = type;
  else
    init = error_mark_node;

  return init;
}

/* Create the VAR_DECL for __FUNCTION__ etc. ID is the name to give
   the decl, LOC is the location to give the decl, NAME is the
   initialization string and TYPE_DEP indicates whether NAME depended
   on the type of the function. We make use of that to detect
   __PRETTY_FUNCTION__ inside a template fn. This is being done lazily
   at the point of first use, so we mustn't push the decl now.  */

static tree
cp_make_fname_decl (location_t loc, tree id, int type_dep)
{
  const char *const name = (type_dep && processing_template_decl
                            ? NULL : fname_as_string (type_dep));
  tree type;
  tree init = cp_fname_init (name, &type);
  tree decl = build_decl (loc, VAR_DECL, id, type);

  if (name)
    free (CONST_CAST (char *, name));

  /* As we're using pushdecl_with_scope, we must set the context.  */
  DECL_CONTEXT (decl) = current_function_decl;
  DECL_PRETTY_FUNCTION_P (decl) = type_dep;

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

  TREE_USED (decl) = 1;

  if (current_function_decl)
    {
      struct cp_binding_level *b = current_binding_level;
      if (b->kind == sk_function_parms)
        return error_mark_node;
      while (b->level_chain->kind != sk_function_parms)
        b = b->level_chain;
      pushdecl_with_scope (decl, b, /*is_friend=*/false);
      cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,
                      LOOKUP_ONLYCONVERTING);
    }
  else
    pushdecl_top_level_and_finish (decl, init);

  return decl;
}

static tree
builtin_function_1 (tree decl, tree context, bool is_global)
{
  tree          id = DECL_NAME (decl);
  const char *name = IDENTIFIER_POINTER (id);

  retrofit_lang_decl (decl);

  DECL_ARTIFICIAL (decl) = 1;
  SET_OVERLOADED_OPERATOR_CODE (decl, ERROR_MARK);
  SET_DECL_LANGUAGE (decl, lang_c);
  /* Runtime library routines are, by definition, available in an
     external shared object.  */
  DECL_VISIBILITY (decl) = VISIBILITY_DEFAULT;
  DECL_VISIBILITY_SPECIFIED (decl) = 1;

  DECL_CONTEXT (decl) = context;

  if (is_global)
    pushdecl_top_level (decl);
  else
    pushdecl (decl);

  /* A function in the user's namespace should have an explicit
     declaration before it is used.  Mark the built-in function as
     anticipated but not actually declared.  */
  if (name[0] != '_' || name[1] != '_')
    DECL_ANTICIPATED (decl) = 1;
  else if (strncmp (name + 2, "builtin_", strlen ("builtin_")) != 0)
    {
      size_t len = strlen (name);

      /* Treat __*_chk fortification functions as anticipated as well,
         unless they are __builtin_*.  */
      if (len > strlen ("___chk")
          && memcmp (name + len - strlen ("_chk"),
                     "_chk", strlen ("_chk") + 1) == 0)
        DECL_ANTICIPATED (decl) = 1;
    }

  return decl;
}

tree
cxx_builtin_function (tree decl)
{
  tree          id = DECL_NAME (decl);
  const char *name = IDENTIFIER_POINTER (id);
  /* All builtins that don't begin with an '_' should additionally
     go in the 'std' namespace.  */
  if (name[0] != '_')
    {
      tree decl2 = copy_node(decl);
      push_namespace (std_identifier);
      builtin_function_1 (decl2, std_node, false);
      pop_namespace ();
    }

  return builtin_function_1 (decl, NULL_TREE, false);
}

/* Like cxx_builtin_function, but guarantee the function is added to the global
   scope.  This is to allow function specific options to add new machine
   dependent builtins when the target ISA changes via attribute((target(...)))
   which saves space on program startup if the program does not use non-generic
   ISAs.  */

tree
cxx_builtin_function_ext_scope (tree decl)
{

  tree          id = DECL_NAME (decl);
  const char *name = IDENTIFIER_POINTER (id);
  /* All builtins that don't begin with an '_' should additionally
     go in the 'std' namespace.  */
  if (name[0] != '_')
    {
      tree decl2 = copy_node(decl);
      push_namespace (std_identifier);
      builtin_function_1 (decl2, std_node, true);
      pop_namespace ();
    }

  return builtin_function_1 (decl, NULL_TREE, true);
}

/* Generate a FUNCTION_DECL with the typical flags for a runtime library
   function.  Not called directly.  */

static tree
build_library_fn_1 (tree name, enum tree_code operator_code, tree type)
{
  tree fn = build_lang_decl (FUNCTION_DECL, name, type);
  DECL_EXTERNAL (fn) = 1;
  TREE_PUBLIC (fn) = 1;
  DECL_ARTIFICIAL (fn) = 1;
  SET_OVERLOADED_OPERATOR_CODE (fn, operator_code);
  SET_DECL_LANGUAGE (fn, lang_c);
  /* Runtime library routines are, by definition, available in an
     external shared object.  */
  DECL_VISIBILITY (fn) = VISIBILITY_DEFAULT;
  DECL_VISIBILITY_SPECIFIED (fn) = 1;
  return fn;
}

/* Returns the _DECL for a library function with C linkage.
   We assume that such functions never throw; if this is incorrect,
   callers should unset TREE_NOTHROW.  */

static tree
build_library_fn (tree name, tree type)
{
  tree fn = build_library_fn_1 (name, ERROR_MARK, type);
  TREE_NOTHROW (fn) = 1;
  return fn;
}

/* Returns the _DECL for a library function with C++ linkage.  */

static tree
build_cp_library_fn (tree name, enum tree_code operator_code, tree type)
{
  tree fn = build_library_fn_1 (name, operator_code, type);
  TREE_NOTHROW (fn) = TYPE_NOTHROW_P (type);
  DECL_CONTEXT (fn) = FROB_CONTEXT (current_namespace);
  SET_DECL_LANGUAGE (fn, lang_cplusplus);
  return fn;
}

/* Like build_library_fn, but takes a C string instead of an
   IDENTIFIER_NODE.  */

tree
build_library_fn_ptr (const char* name, tree type)
{
  return build_library_fn (get_identifier (name), type);
}

/* Like build_cp_library_fn, but takes a C string instead of an
   IDENTIFIER_NODE.  */

tree
build_cp_library_fn_ptr (const char* name, tree type)
{
  return build_cp_library_fn (get_identifier (name), ERROR_MARK, type);
}

/* Like build_library_fn, but also pushes the function so that we will
   be able to find it via IDENTIFIER_GLOBAL_VALUE.  Also, the function
   may throw exceptions listed in RAISES.  */

tree
push_library_fn (tree name, tree type, tree raises)
{
  tree fn;

  if (raises)
    type = build_exception_variant (type, raises);

  fn = build_library_fn (name, type);
  pushdecl_top_level (fn);
  return fn;
}

/* Like build_cp_library_fn, but also pushes the function so that it
   will be found by normal lookup.  */

static tree
push_cp_library_fn (enum tree_code operator_code, tree type)
{
  tree fn = build_cp_library_fn (ansi_opname (operator_code),
                                 operator_code,
                                 type);
  pushdecl (fn);
  return fn;
}

/* Like push_library_fn, but takes a TREE_LIST of parm types rather than
   a FUNCTION_TYPE.  */

tree
push_void_library_fn (tree name, tree parmtypes)
{
  tree type = build_function_type (void_type_node, parmtypes);
  return push_library_fn (name, type, NULL_TREE);
}

/* Like push_library_fn, but also note that this function throws
   and does not return.  Used for __throw_foo and the like.  */

tree
push_throw_library_fn (tree name, tree type)
{
  tree fn = push_library_fn (name, type, NULL_TREE);
  TREE_THIS_VOLATILE (fn) = 1;
  TREE_NOTHROW (fn) = 0;
  return fn;
}
\f
/* When we call finish_struct for an anonymous union, we create
   default copy constructors and such.  But, an anonymous union
   shouldn't have such things; this function undoes the damage to the
   anonymous union type T.

   (The reason that we create the synthesized methods is that we don't
   distinguish `union { int i; }' from `typedef union { int i; } U'.
   The first is an anonymous union; the second is just an ordinary
   union type.)  */

void
fixup_anonymous_aggr (tree t)
{
  tree *q;

  /* Wipe out memory of synthesized methods.  */
  TYPE_HAS_USER_CONSTRUCTOR (t) = 0;
  TYPE_HAS_DEFAULT_CONSTRUCTOR (t) = 0;
  TYPE_HAS_COPY_CTOR (t) = 0;
  TYPE_HAS_CONST_COPY_CTOR (t) = 0;
  TYPE_HAS_COPY_ASSIGN (t) = 0;
  TYPE_HAS_CONST_COPY_ASSIGN (t) = 0;

  /* Splice the implicitly generated functions out of the TYPE_METHODS
     list.  */
  q = &TYPE_METHODS (t);
  while (*q)
    {
      if (DECL_ARTIFICIAL (*q))
        *q = TREE_CHAIN (*q);
      else
        q = &DECL_CHAIN (*q);
    }

  /* ISO C++ 9.5.3.  Anonymous unions may not have function members.  */
  if (TYPE_METHODS (t))
    {
      tree decl = TYPE_MAIN_DECL (t);

      if (TREE_CODE (t) != UNION_TYPE)
        error_at (DECL_SOURCE_LOCATION (decl), 
                  "an anonymous struct cannot have function members");
      else
        error_at (DECL_SOURCE_LOCATION (decl),
                  "an anonymous union cannot have function members");
    }

  /* Anonymous aggregates cannot have fields with ctors, dtors or complex
     assignment operators (because they cannot have these methods themselves).
     For anonymous unions this is already checked because they are not allowed
     in any union, otherwise we have to check it.  */
  if (TREE_CODE (t) != UNION_TYPE)
    {
      tree field, type;

      for (field = TYPE_FIELDS (t); field; field = DECL_CHAIN (field))
        if (TREE_CODE (field) == FIELD_DECL)
          {
            type = TREE_TYPE (field);
            if (CLASS_TYPE_P (type))
              {
                if (TYPE_NEEDS_CONSTRUCTING (type))
                  error ("member %q+#D with constructor not allowed "
                         "in anonymous aggregate", field);
                if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type))
                  error ("member %q+#D with destructor not allowed "
                         "in anonymous aggregate", field);
                if (TYPE_HAS_COMPLEX_COPY_ASSIGN (type))
                  error ("member %q+#D with copy assignment operator "
                         "not allowed in anonymous aggregate", field);
              }
          }
    }
}

/* Make sure that a declaration with no declarator is well-formed, i.e.
   just declares a tagged type or anonymous union.

   Returns the type declared; or NULL_TREE if none.  */

tree
check_tag_decl (cp_decl_specifier_seq *declspecs)
{
  int saw_friend = declspecs->specs[(int)ds_friend] != 0;
  int saw_typedef = declspecs->specs[(int)ds_typedef] != 0;
  /* If a class, struct, or enum type is declared by the DECLSPECS
     (i.e, if a class-specifier, enum-specifier, or non-typename
     elaborated-type-specifier appears in the DECLSPECS),
     DECLARED_TYPE is set to the corresponding type.  */
  tree declared_type = NULL_TREE;
  bool error_p = false;

  if (declspecs->multiple_types_p)
    error ("multiple types in one declaration");
  else if (declspecs->redefined_builtin_type)
    {
      if (!in_system_header)
        permerror (input_location, "redeclaration of C++ built-in type %qT",
                   declspecs->redefined_builtin_type);
      return NULL_TREE;
    }

  if (declspecs->type
      && TYPE_P (declspecs->type)
      && ((TREE_CODE (declspecs->type) != TYPENAME_TYPE
           && MAYBE_CLASS_TYPE_P (declspecs->type))
          || TREE_CODE (declspecs->type) == ENUMERAL_TYPE))
    declared_type = declspecs->type;
  else if (declspecs->type == error_mark_node)
    error_p = true;
  if (declared_type == NULL_TREE && ! saw_friend && !error_p)
    permerror (input_location, "declaration does not declare anything");
  /* Check for an anonymous union.  */
  else if (declared_type && RECORD_OR_UNION_CODE_P (TREE_CODE (declared_type))
           && TYPE_ANONYMOUS_P (declared_type))
    {
      /* 7/3 In a simple-declaration, the optional init-declarator-list
         can be omitted only when declaring a class (clause 9) or
         enumeration (7.2), that is, when the decl-specifier-seq contains
         either a class-specifier, an elaborated-type-specifier with
         a class-key (9.1), or an enum-specifier.  In these cases and
         whenever a class-specifier or enum-specifier is present in the
         decl-specifier-seq, the identifiers in these specifiers are among
         the names being declared by the declaration (as class-name,
         enum-names, or enumerators, depending on the syntax).  In such
         cases, and except for the declaration of an unnamed bit-field (9.6),
         the decl-specifier-seq shall introduce one or more names into the
         program, or shall redeclare a name introduced by a previous
         declaration.  [Example:
             enum { };                  // ill-formed
             typedef class { };         // ill-formed
         --end example]  */
      if (saw_typedef)
        {
          error ("missing type-name in typedef-declaration");
          return NULL_TREE;
        }
      /* Anonymous unions are objects, so they can have specifiers.  */;
      SET_ANON_AGGR_TYPE_P (declared_type);

      if (TREE_CODE (declared_type) != UNION_TYPE && !in_system_header)
        pedwarn (input_location, OPT_pedantic, "ISO C++ prohibits anonymous structs");
    }

  else
    {
      if (declspecs->specs[(int)ds_inline]
          || declspecs->specs[(int)ds_virtual])
        error ("%qs can only be specified for functions",
               declspecs->specs[(int)ds_inline]
               ? "inline" : "virtual");
      else if (saw_friend
               && (!current_class_type
                   || current_scope () != current_class_type))
        error ("%<friend%> can only be specified inside a class");
      else if (declspecs->specs[(int)ds_explicit])
        error ("%<explicit%> can only be specified for constructors");
      else if (declspecs->storage_class)
        error ("a storage class can only be specified for objects "
               "and functions");
      else if (declspecs->specs[(int)ds_const]
               || declspecs->specs[(int)ds_volatile]
               || declspecs->specs[(int)ds_restrict]
               || declspecs->specs[(int)ds_thread])
        error ("qualifiers can only be specified for objects "
               "and functions");
      else if (saw_typedef)
        warning (0, "%<typedef%> was ignored in this declaration");
      else if (declspecs->specs[(int) ds_constexpr])
        error ("%<constexpr%> cannot be used for type declarations");
    }

  return declared_type;
}

/* 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.

   C++: may have to grok the declspecs to learn about static,
   complain for anonymous unions.

   Returns the TYPE declared -- or NULL_TREE if none.  */

tree
shadow_tag (cp_decl_specifier_seq *declspecs)
{
  tree t = check_tag_decl (declspecs);

  if (!t)
    return NULL_TREE;

  if (declspecs->attributes)
    {
      warning (0, "attribute ignored in declaration of %q+#T", t);
      warning (0, "attribute for %q+#T must follow the %qs keyword",
               t, class_key_or_enum_as_string (t));

    }

  if (maybe_process_partial_specialization (t) == error_mark_node)
    return NULL_TREE;

  /* This is where the variables in an anonymous union are
     declared.  An anonymous union declaration looks like:
     union { ... } ;
     because there is no declarator after the union, the parser
     sends that declaration here.  */
  if (ANON_AGGR_TYPE_P (t))
    {
      fixup_anonymous_aggr (t);

      if (TYPE_FIELDS (t))
        {
          tree decl = grokdeclarator (/*declarator=*/NULL,
                                      declspecs, NORMAL, 0, NULL);