2012-04-15 Fabien Chêne <fabien@gcc.gnu.org>

[pf3gnuchains/gcc-fork.git] / gcc / cp / name-lookup.c

/* Definitions for C++ name lookup routines.
   Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
   Free Software Foundation, Inc.
   Contributed by Gabriel Dos Reis <gdr@integrable-solutions.net>

This file is part of GCC.

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

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

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

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "flags.h"
#include "tree.h"
#include "cp-tree.h"
#include "name-lookup.h"
#include "timevar.h"
#include "diagnostic-core.h"
#include "intl.h"
#include "debug.h"
#include "c-family/c-pragma.h"
#include "params.h"
#include "pointer-set.h"

/* The bindings for a particular name in a particular scope.  */

struct scope_binding {
  tree value;
  tree type;
};
#define EMPTY_SCOPE_BINDING { NULL_TREE, NULL_TREE }

static cp_binding_level *innermost_nonclass_level (void);
static cxx_binding *binding_for_name (cp_binding_level *, tree);
static tree push_overloaded_decl (tree, int, bool);
static bool lookup_using_namespace (tree, struct scope_binding *, tree,
                                    tree, int);
static bool qualified_lookup_using_namespace (tree, tree,
                                              struct scope_binding *, int);
static tree lookup_type_current_level (tree);
static tree push_using_directive (tree);
static tree lookup_extern_c_fun_in_all_ns (tree);
static void diagnose_name_conflict (tree, tree);

/* The :: namespace.  */

tree global_namespace;

/* The name of the anonymous namespace, throughout this translation
   unit.  */
static GTY(()) tree anonymous_namespace_name;

/* Initialize anonymous_namespace_name if necessary, and return it.  */

static tree
get_anonymous_namespace_name (void)
{
  if (!anonymous_namespace_name)
    {
      /* The anonymous namespace has to have a unique name
         if typeinfo objects are being compared by name.  */
      if (! flag_weak || ! SUPPORTS_ONE_ONLY)
       anonymous_namespace_name = get_file_function_name ("N");
      else
       /* The demangler expects anonymous namespaces to be called
          something starting with '_GLOBAL__N_'.  */
       anonymous_namespace_name = get_identifier ("_GLOBAL__N_1");
    }
  return anonymous_namespace_name;
}

/* Compute the chain index of a binding_entry given the HASH value of its
   name and the total COUNT of chains.  COUNT is assumed to be a power
   of 2.  */

#define ENTRY_INDEX(HASH, COUNT) (((HASH) >> 3) & ((COUNT) - 1))

/* A free list of "binding_entry"s awaiting for re-use.  */

static GTY((deletable)) binding_entry free_binding_entry = NULL;

/* Create a binding_entry object for (NAME, TYPE).  */

static inline binding_entry
binding_entry_make (tree name, tree type)
{
  binding_entry entry;

  if (free_binding_entry)
    {
      entry = free_binding_entry;
      free_binding_entry = entry->chain;
    }
  else
    entry = ggc_alloc_binding_entry_s ();

  entry->name = name;
  entry->type = type;
  entry->chain = NULL;

  return entry;
}

/* Put ENTRY back on the free list.  */
#if 0
static inline void
binding_entry_free (binding_entry entry)
{
  entry->name = NULL;
  entry->type = NULL;
  entry->chain = free_binding_entry;
  free_binding_entry = entry;
}
#endif

/* The datatype used to implement the mapping from names to types at
   a given scope.  */
struct GTY(()) binding_table_s {
  /* Array of chains of "binding_entry"s  */
  binding_entry * GTY((length ("%h.chain_count"))) chain;

  /* The number of chains in this table.  This is the length of the
     member "chain" considered as an array.  */
  size_t chain_count;

  /* Number of "binding_entry"s in this table.  */
  size_t entry_count;
};

/* Construct TABLE with an initial CHAIN_COUNT.  */

static inline void
binding_table_construct (binding_table table, size_t chain_count)
{
  table->chain_count = chain_count;
  table->entry_count = 0;
  table->chain = ggc_alloc_cleared_vec_binding_entry (table->chain_count);
}

/* Make TABLE's entries ready for reuse.  */
#if 0
static void
binding_table_free (binding_table table)
{
  size_t i;
  size_t count;

  if (table == NULL)
    return;

  for (i = 0, count = table->chain_count; i < count; ++i)
    {
      binding_entry temp = table->chain[i];
      while (temp != NULL)
        {
          binding_entry entry = temp;
          temp = entry->chain;
          binding_entry_free (entry);
        }
      table->chain[i] = NULL;
    }
  table->entry_count = 0;
}
#endif

/* Allocate a table with CHAIN_COUNT, assumed to be a power of two.  */

static inline binding_table
binding_table_new (size_t chain_count)
{
  binding_table table = ggc_alloc_binding_table_s ();
  table->chain = NULL;
  binding_table_construct (table, chain_count);
  return table;
}

/* Expand TABLE to twice its current chain_count.  */

static void
binding_table_expand (binding_table table)
{
  const size_t old_chain_count = table->chain_count;
  const size_t old_entry_count = table->entry_count;
  const size_t new_chain_count = 2 * old_chain_count;
  binding_entry *old_chains = table->chain;
  size_t i;

  binding_table_construct (table, new_chain_count);
  for (i = 0; i < old_chain_count; ++i)
    {
      binding_entry entry = old_chains[i];
      for (; entry != NULL; entry = old_chains[i])
        {
          const unsigned int hash = IDENTIFIER_HASH_VALUE (entry->name);
          const size_t j = ENTRY_INDEX (hash, new_chain_count);

          old_chains[i] = entry->chain;
          entry->chain = table->chain[j];
          table->chain[j] = entry;
        }
    }
  table->entry_count = old_entry_count;
}

/* Insert a binding for NAME to TYPE into TABLE.  */

static void
binding_table_insert (binding_table table, tree name, tree type)
{
  const unsigned int hash = IDENTIFIER_HASH_VALUE (name);
  const size_t i = ENTRY_INDEX (hash, table->chain_count);
  binding_entry entry = binding_entry_make (name, type);

  entry->chain = table->chain[i];
  table->chain[i] = entry;
  ++table->entry_count;

  if (3 * table->chain_count < 5 * table->entry_count)
    binding_table_expand (table);
}

/* Return the binding_entry, if any, that maps NAME.  */

binding_entry
binding_table_find (binding_table table, tree name)
{
  const unsigned int hash = IDENTIFIER_HASH_VALUE (name);
  binding_entry entry = table->chain[ENTRY_INDEX (hash, table->chain_count)];

  while (entry != NULL && entry->name != name)
    entry = entry->chain;

  return entry;
}

/* Apply PROC -- with DATA -- to all entries in TABLE.  */

void
binding_table_foreach (binding_table table, bt_foreach_proc proc, void *data)
{
  const size_t chain_count = table->chain_count;
  size_t i;

  for (i = 0; i < chain_count; ++i)
    {
      binding_entry entry = table->chain[i];
      for (; entry != NULL; entry = entry->chain)
        proc (entry, data);
    }
}
\f
#ifndef ENABLE_SCOPE_CHECKING
#  define ENABLE_SCOPE_CHECKING 0
#else
#  define ENABLE_SCOPE_CHECKING 1
#endif

/* A free list of "cxx_binding"s, connected by their PREVIOUS.  */

static GTY((deletable)) cxx_binding *free_bindings;

/* Initialize VALUE and TYPE field for BINDING, and set the PREVIOUS
   field to NULL.  */

static inline void
cxx_binding_init (cxx_binding *binding, tree value, tree type)
{
  binding->value = value;
  binding->type = type;
  binding->previous = NULL;
}

/* (GC)-allocate a binding object with VALUE and TYPE member initialized.  */

static cxx_binding *
cxx_binding_make (tree value, tree type)
{
  cxx_binding *binding;
  if (free_bindings)
    {
      binding = free_bindings;
      free_bindings = binding->previous;
    }
  else
    binding = ggc_alloc_cxx_binding ();

  cxx_binding_init (binding, value, type);

  return binding;
}

/* Put BINDING back on the free list.  */

static inline void
cxx_binding_free (cxx_binding *binding)
{
  binding->scope = NULL;
  binding->previous = free_bindings;
  free_bindings = binding;
}

/* Create a new binding for NAME (with the indicated VALUE and TYPE
   bindings) in the class scope indicated by SCOPE.  */

static cxx_binding *
new_class_binding (tree name, tree value, tree type, cp_binding_level *scope)
{
  cp_class_binding *cb;
  cxx_binding *binding;

    cb = VEC_safe_push (cp_class_binding, gc, scope->class_shadowed, NULL);

  cb->identifier = name;
  cb->base = binding = cxx_binding_make (value, type);
  binding->scope = scope;
  return binding;
}

/* Make DECL the innermost binding for ID.  The LEVEL is the binding
   level at which this declaration is being bound.  */

static void
push_binding (tree id, tree decl, cp_binding_level* level)
{
  cxx_binding *binding;

  if (level != class_binding_level)
    {
      binding = cxx_binding_make (decl, NULL_TREE);
      binding->scope = level;
    }
  else
    binding = new_class_binding (id, decl, /*type=*/NULL_TREE, level);

  /* Now, fill in the binding information.  */
  binding->previous = IDENTIFIER_BINDING (id);
  INHERITED_VALUE_BINDING_P (binding) = 0;
  LOCAL_BINDING_P (binding) = (level != class_binding_level);

  /* And put it on the front of the list of bindings for ID.  */
  IDENTIFIER_BINDING (id) = binding;
}

/* Remove the binding for DECL which should be the innermost binding
   for ID.  */

void
pop_binding (tree id, tree decl)
{
  cxx_binding *binding;

  if (id == NULL_TREE)
    /* It's easiest to write the loops that call this function without
       checking whether or not the entities involved have names.  We
       get here for such an entity.  */
    return;

  /* Get the innermost binding for ID.  */
  binding = IDENTIFIER_BINDING (id);

  /* The name should be bound.  */
  gcc_assert (binding != NULL);

  /* The DECL will be either the ordinary binding or the type
     binding for this identifier.  Remove that binding.  */
  if (binding->value == decl)
    binding->value = NULL_TREE;
  else
    {
      gcc_assert (binding->type == decl);
      binding->type = NULL_TREE;
    }

  if (!binding->value && !binding->type)
    {
      /* We're completely done with the innermost binding for this
         identifier.  Unhook it from the list of bindings.  */
      IDENTIFIER_BINDING (id) = binding->previous;

      /* Add it to the free list.  */
      cxx_binding_free (binding);
    }
}

/* Strip non dependent using declarations.  */

tree
strip_using_decl (tree decl)
{
  if (decl == NULL_TREE)
    return NULL_TREE;

  while (TREE_CODE (decl) == USING_DECL && !DECL_DEPENDENT_P (decl))
    decl = USING_DECL_DECLS (decl);
  return decl;
}

/* BINDING records an existing declaration for a name in the current scope.
   But, DECL is another declaration for that same identifier in the
   same scope.  This is the `struct stat' hack whereby a non-typedef
   class name or enum-name can be bound at the same level as some other
   kind of entity.
   3.3.7/1

     A class name (9.1) or enumeration name (7.2) can be hidden by the
     name of an object, function, or enumerator declared in the same scope.
     If a class or enumeration name and an object, function, or enumerator
     are declared in the same scope (in any order) with the same name, the
     class or enumeration name is hidden wherever the object, function, or
     enumerator name is visible.

   It's the responsibility of the caller to check that
   inserting this name is valid here.  Returns nonzero if the new binding
   was successful.  */

static bool
supplement_binding_1 (cxx_binding *binding, tree decl)
{
  tree bval = binding->value;
  bool ok = true;
  tree target_bval = strip_using_decl (bval);
  tree target_decl = strip_using_decl (decl);

  if (TREE_CODE (target_decl) == TYPE_DECL && DECL_ARTIFICIAL (target_decl)
      && target_decl != target_bval
      && (TREE_CODE (target_bval) != TYPE_DECL
          /* We allow pushing an enum multiple times in a class
             template in order to handle late matching of underlying
             type on an opaque-enum-declaration followed by an
             enum-specifier.  */
          || (TREE_CODE (TREE_TYPE (target_decl)) == ENUMERAL_TYPE
              && TREE_CODE (TREE_TYPE (target_bval)) == ENUMERAL_TYPE
              && (dependent_type_p (ENUM_UNDERLYING_TYPE
                                    (TREE_TYPE (target_decl)))
                  || dependent_type_p (ENUM_UNDERLYING_TYPE
                                       (TREE_TYPE (target_bval)))))))
    /* The new name is the type name.  */
    binding->type = decl;
  else if (/* TARGET_BVAL is null when push_class_level_binding moves
              an inherited type-binding out of the way to make room
              for a new value binding.  */
           !target_bval
           /* TARGET_BVAL is error_mark_node when TARGET_DECL's name
              has been used in a non-class scope prior declaration.
              In that case, we should have already issued a
              diagnostic; for graceful error recovery purpose, pretend
              this was the intended declaration for that name.  */
           || target_bval == error_mark_node
           /* If TARGET_BVAL is anticipated but has not yet been
              declared, pretend it is not there at all.  */
           || (TREE_CODE (target_bval) == FUNCTION_DECL
               && DECL_ANTICIPATED (target_bval)
               && !DECL_HIDDEN_FRIEND_P (target_bval)))
    binding->value = decl;
  else if (TREE_CODE (target_bval) == TYPE_DECL
           && DECL_ARTIFICIAL (target_bval)
           && target_decl != target_bval
           && (TREE_CODE (target_decl) != TYPE_DECL
               || same_type_p (TREE_TYPE (target_decl),
                               TREE_TYPE (target_bval))))
    {
      /* The old binding was a type name.  It was placed in
         VALUE field because it was thought, at the point it was
         declared, to be the only entity with such a name.  Move the
         type name into the type slot; it is now hidden by the new
         binding.  */
      binding->type = bval;
      binding->value = decl;
      binding->value_is_inherited = false;
    }
  else if (TREE_CODE (target_bval) == TYPE_DECL
           && TREE_CODE (target_decl) == TYPE_DECL
           && DECL_NAME (target_decl) == DECL_NAME (target_bval)
           && binding->scope->kind != sk_class
           && (same_type_p (TREE_TYPE (target_decl), TREE_TYPE (target_bval))
               /* If either type involves template parameters, we must
                  wait until instantiation.  */
               || uses_template_parms (TREE_TYPE (target_decl))
               || uses_template_parms (TREE_TYPE (target_bval))))
    /* We have two typedef-names, both naming the same type to have
       the same name.  In general, this is OK because of:

         [dcl.typedef]

         In a given scope, a typedef specifier can be used to redefine
         the name of any type declared in that scope to refer to the
         type to which it already refers.

       However, in class scopes, this rule does not apply due to the
       stricter language in [class.mem] prohibiting redeclarations of
       members.  */
    ok = false;
  /* There can be two block-scope declarations of the same variable,
     so long as they are `extern' declarations.  However, there cannot
     be two declarations of the same static data member:

       [class.mem]

       A member shall not be declared twice in the
       member-specification.  */
  else if (TREE_CODE (target_decl) == VAR_DECL
           && TREE_CODE (target_bval) == VAR_DECL
           && DECL_EXTERNAL (target_decl) && DECL_EXTERNAL (target_bval)
           && !DECL_CLASS_SCOPE_P (target_decl))
    {
      duplicate_decls (decl, binding->value, /*newdecl_is_friend=*/false);
      ok = false;
    }
  else if (TREE_CODE (decl) == NAMESPACE_DECL
           && TREE_CODE (bval) == NAMESPACE_DECL
           && DECL_NAMESPACE_ALIAS (decl)
           && DECL_NAMESPACE_ALIAS (bval)
           && ORIGINAL_NAMESPACE (bval) == ORIGINAL_NAMESPACE (decl))
    /* [namespace.alias]

      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.  */
    ok = false;
  else
    {
      diagnose_name_conflict (decl, bval);
      ok = false;
    }

  return ok;
}

/* Diagnose a name conflict between DECL and BVAL.  */

static void
diagnose_name_conflict (tree decl, tree bval)
{
  if (TREE_CODE (decl) == TREE_CODE (bval)
      && (TREE_CODE (decl) != TYPE_DECL
          || (DECL_ARTIFICIAL (decl) && DECL_ARTIFICIAL (bval))
          || (!DECL_ARTIFICIAL (decl) && !DECL_ARTIFICIAL (bval)))
      && !is_overloaded_fn (decl))
    error ("redeclaration of %q#D", decl);
  else
    error ("%q#D conflicts with a previous declaration", decl);

  inform (input_location, "previous declaration %q+#D", bval);
}

/* Wrapper for supplement_binding_1.  */

static bool
supplement_binding (cxx_binding *binding, tree decl)
{
  bool ret;
  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  ret = supplement_binding_1 (binding, decl);
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
  return ret;
}

/* Add DECL to the list of things declared in B.  */

static void
add_decl_to_level (tree decl, cp_binding_level *b)
{
  /* We used to record virtual tables as if they were ordinary
     variables, but no longer do so.  */
  gcc_assert (!(TREE_CODE (decl) == VAR_DECL && DECL_VIRTUAL_P (decl)));

  if (TREE_CODE (decl) == NAMESPACE_DECL
      && !DECL_NAMESPACE_ALIAS (decl))
    {
      DECL_CHAIN (decl) = b->namespaces;
      b->namespaces = decl;
    }
  else
    {
      /* We build up the list in reverse order, and reverse it later if
         necessary.  */
      TREE_CHAIN (decl) = b->names;
      b->names = decl;

      /* If appropriate, add decl to separate list of statics.  We
         include extern variables because they might turn out to be
         static later.  It's OK for this list to contain a few false
         positives.  */
      if (b->kind == sk_namespace)
        if ((TREE_CODE (decl) == VAR_DECL
             && (TREE_STATIC (decl) || DECL_EXTERNAL (decl)))
            || (TREE_CODE (decl) == FUNCTION_DECL
                && (!TREE_PUBLIC (decl) || DECL_DECLARED_INLINE_P (decl))))
          VEC_safe_push (tree, gc, b->static_decls, decl);
    }
}

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

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

static tree
pushdecl_maybe_friend_1 (tree x, bool is_friend)
{
  tree t;
  tree name;
  int need_new_binding;

  if (x == error_mark_node)
    return error_mark_node;

  need_new_binding = 1;

  if (DECL_TEMPLATE_PARM_P (x))
    /* Template parameters have no context; they are not X::T even
       when declared within a class or namespace.  */
    ;
  else
    {
      if (current_function_decl && x != current_function_decl
          /* A local declaration for a function doesn't constitute
             nesting.  */
          && TREE_CODE (x) != FUNCTION_DECL
          /* A local declaration for an `extern' variable is in the
             scope of the current namespace, not the current
             function.  */
          && !(TREE_CODE (x) == VAR_DECL && DECL_EXTERNAL (x))
          /* When parsing the parameter list of a function declarator,
             don't set DECL_CONTEXT to an enclosing function.  When we
             push the PARM_DECLs in order to process the function body,
             current_binding_level->this_entity will be set.  */
          && !(TREE_CODE (x) == PARM_DECL
               && current_binding_level->kind == sk_function_parms
               && current_binding_level->this_entity == NULL)
          && !DECL_CONTEXT (x))
        DECL_CONTEXT (x) = current_function_decl;

      /* If this is the declaration for a namespace-scope function,
         but the declaration itself is in a local scope, mark the
         declaration.  */
      if (TREE_CODE (x) == FUNCTION_DECL
          && DECL_NAMESPACE_SCOPE_P (x)
          && current_function_decl
          && x != current_function_decl)
        DECL_LOCAL_FUNCTION_P (x) = 1;
    }

  name = DECL_NAME (x);
  if (name)
    {
      int different_binding_level = 0;

      if (TREE_CODE (name) == TEMPLATE_ID_EXPR)
        name = TREE_OPERAND (name, 0);

      /* In case this decl was explicitly namespace-qualified, look it
         up in its namespace context.  */
      if (DECL_NAMESPACE_SCOPE_P (x) && namespace_bindings_p ())
        t = namespace_binding (name, DECL_CONTEXT (x));
      else
        t = lookup_name_innermost_nonclass_level (name);

      /* [basic.link] If there is a visible declaration of an entity
         with linkage having the same name and type, ignoring entities
         declared outside the innermost enclosing namespace scope, the
         block scope declaration declares that same entity and
         receives the linkage of the previous declaration.  */
      if (! t && current_function_decl && x != current_function_decl
          && (TREE_CODE (x) == FUNCTION_DECL || TREE_CODE (x) == VAR_DECL)
          && DECL_EXTERNAL (x))
        {
          /* Look in block scope.  */
          t = innermost_non_namespace_value (name);
          /* Or in the innermost namespace.  */
          if (! t)
            t = namespace_binding (name, DECL_CONTEXT (x));
          /* Does it have linkage?  Note that if this isn't a DECL, it's an
             OVERLOAD, which is OK.  */
          if (t && DECL_P (t) && ! (TREE_STATIC (t) || DECL_EXTERNAL (t)))
            t = NULL_TREE;
          if (t)
            different_binding_level = 1;
        }

      /* If we are declaring a function, and the result of name-lookup
         was an OVERLOAD, look for an overloaded instance that is
         actually the same as the function we are declaring.  (If
         there is one, we have to merge our declaration with the
         previous declaration.)  */
      if (t && TREE_CODE (t) == OVERLOAD)
        {
          tree match;

          if (TREE_CODE (x) == FUNCTION_DECL)
            for (match = t; match; match = OVL_NEXT (match))
              {
                if (decls_match (OVL_CURRENT (match), x))
                  break;
              }
          else
            /* Just choose one.  */
            match = t;

          if (match)
            t = OVL_CURRENT (match);
          else
            t = NULL_TREE;
        }

      if (t && t != error_mark_node)
        {
          if (different_binding_level)
            {
              if (decls_match (x, t))
                /* The standard only says that the local extern
                   inherits linkage from the previous decl; in
                   particular, default args are not shared.  Add
                   the decl into a hash table to make sure only
                   the previous decl in this case is seen by the
                   middle end.  */
                {
                  struct cxx_int_tree_map *h;
                  void **loc;

                  TREE_PUBLIC (x) = TREE_PUBLIC (t);

                  if (cp_function_chain->extern_decl_map == NULL)
                    cp_function_chain->extern_decl_map
                      = htab_create_ggc (20, cxx_int_tree_map_hash,
                                         cxx_int_tree_map_eq, NULL);

                  h = ggc_alloc_cxx_int_tree_map ();
                  h->uid = DECL_UID (x);
                  h->to = t;
                  loc = htab_find_slot_with_hash
                          (cp_function_chain->extern_decl_map, h,
                           h->uid, INSERT);
                  *(struct cxx_int_tree_map **) loc = h;
                }
            }
          else if (TREE_CODE (t) == PARM_DECL)
            {
              /* Check for duplicate params.  */
              tree d = duplicate_decls (x, t, is_friend);
              if (d)
                return d;
            }
          else if ((DECL_EXTERN_C_FUNCTION_P (x)
                    || DECL_FUNCTION_TEMPLATE_P (x))
                   && is_overloaded_fn (t))
            /* Don't do anything just yet.  */;
          else if (t == wchar_decl_node)
            {
              if (! DECL_IN_SYSTEM_HEADER (x))
                pedwarn (input_location, OPT_pedantic, "redeclaration of %<wchar_t%> as %qT",
                         TREE_TYPE (x));
              
              /* Throw away the redeclaration.  */
              return t;
            }
          else
            {
              tree olddecl = duplicate_decls (x, t, is_friend);

              /* If the redeclaration failed, we can stop at this
                 point.  */
              if (olddecl == error_mark_node)
                return error_mark_node;

              if (olddecl)
                {
                  if (TREE_CODE (t) == TYPE_DECL)
                    SET_IDENTIFIER_TYPE_VALUE (name, TREE_TYPE (t));

                  return t;
                }
              else if (DECL_MAIN_P (x) && TREE_CODE (t) == FUNCTION_DECL)
                {
                  /* A redeclaration of main, but not a duplicate of the
                     previous one.

                     [basic.start.main]

                     This function shall not be overloaded.  */
                  error ("invalid redeclaration of %q+D", t);
                  error ("as %qD", x);
                  /* We don't try to push this declaration since that
                     causes a crash.  */
                  return x;
                }
            }
        }

      /* If x has C linkage-specification, (extern "C"),
         lookup its binding, in case it's already bound to an object.
         The lookup is done in all namespaces.
         If we find an existing binding, make sure it has the same
         exception specification as x, otherwise, bail in error [7.5, 7.6].  */
      if ((TREE_CODE (x) == FUNCTION_DECL)
          && DECL_EXTERN_C_P (x)
          /* We should ignore declarations happening in system headers.  */
          && !DECL_ARTIFICIAL (x)
          && !DECL_IN_SYSTEM_HEADER (x))
        {
          tree previous = lookup_extern_c_fun_in_all_ns (x);
          if (previous
              && !DECL_ARTIFICIAL (previous)
              && !DECL_IN_SYSTEM_HEADER (previous)
              && DECL_CONTEXT (previous) != DECL_CONTEXT (x))
            {
              /* In case either x or previous is declared to throw an exception,
                 make sure both exception specifications are equal.  */
              if (decls_match (x, previous))
                {
                  tree x_exception_spec = NULL_TREE;
                  tree previous_exception_spec = NULL_TREE;

                  x_exception_spec =
                                TYPE_RAISES_EXCEPTIONS (TREE_TYPE (x));
                  previous_exception_spec =
                                TYPE_RAISES_EXCEPTIONS (TREE_TYPE (previous));
                  if (!comp_except_specs (previous_exception_spec,
                                          x_exception_spec,
                                          ce_normal))
                    {
                      pedwarn (input_location, 0,
                               "declaration of %q#D with C language linkage",
                               x);
                      pedwarn (input_location, 0,
                               "conflicts with previous declaration %q+#D",
                               previous);
                      pedwarn (input_location, 0,
                               "due to different exception specifications");
                      return error_mark_node;
                    }
                  if (DECL_ASSEMBLER_NAME_SET_P (previous))
                    SET_DECL_ASSEMBLER_NAME (x,
                                             DECL_ASSEMBLER_NAME (previous));
                }
              else
                {
                  pedwarn (input_location, 0,
                           "declaration of %q#D with C language linkage", x);
                  pedwarn (input_location, 0,
                           "conflicts with previous declaration %q+#D",
                           previous);
                }
            }
        }

      check_template_shadow (x);

      /* If this is a function conjured up by the back end, massage it
         so it looks friendly.  */
      if (DECL_NON_THUNK_FUNCTION_P (x) && ! DECL_LANG_SPECIFIC (x))
        {
          retrofit_lang_decl (x);
          SET_DECL_LANGUAGE (x, lang_c);
        }

      t = x;
      if (DECL_NON_THUNK_FUNCTION_P (x) && ! DECL_FUNCTION_MEMBER_P (x))
        {
          t = push_overloaded_decl (x, PUSH_LOCAL, is_friend);
          if (!namespace_bindings_p ())
            /* We do not need to create a binding for this name;
               push_overloaded_decl will have already done so if
               necessary.  */
            need_new_binding = 0;
        }
      else if (DECL_FUNCTION_TEMPLATE_P (x) && DECL_NAMESPACE_SCOPE_P (x))
        {
          t = push_overloaded_decl (x, PUSH_GLOBAL, is_friend);
          if (t == x)
            add_decl_to_level (x, NAMESPACE_LEVEL (CP_DECL_CONTEXT (t)));
        }

      if (TREE_CODE (t) == FUNCTION_DECL || DECL_FUNCTION_TEMPLATE_P (t))
        check_default_args (t);

      if (t != x || DECL_FUNCTION_TEMPLATE_P (t))
        return t;

      /* If declaring a type as a typedef, copy the type (unless we're
         at line 0), and install this TYPE_DECL as the new type's typedef
         name.  See the extensive comment of set_underlying_type ().  */
      if (TREE_CODE (x) == TYPE_DECL)
        {
          tree type = TREE_TYPE (x);

          if (DECL_IS_BUILTIN (x)
              || (TREE_TYPE (x) != error_mark_node
                  && TYPE_NAME (type) != x
                  /* We don't want to copy the type when all we're
                     doing is making a TYPE_DECL for the purposes of
                     inlining.  */
                  && (!TYPE_NAME (type)
                      || TYPE_NAME (type) != DECL_ABSTRACT_ORIGIN (x))))
            set_underlying_type (x);

          if (type != error_mark_node
              && TYPE_NAME (type)
              && TYPE_IDENTIFIER (type))
            set_identifier_type_value (DECL_NAME (x), x);

          /* If this is a locally defined typedef in a function that
             is not a template instantation, record it to implement
             -Wunused-local-typedefs.  */
          if (current_instantiation () == NULL
              || (current_instantiation ()->decl != current_function_decl))
          record_locally_defined_typedef (x);
        }

      /* Multiple external decls of the same identifier ought to match.

         We get warnings about inline functions where they are defined.
         We get warnings about other functions from push_overloaded_decl.

         Avoid duplicate warnings where they are used.  */
      if (TREE_PUBLIC (x) && TREE_CODE (x) != FUNCTION_DECL)
        {
          tree decl;

          decl = IDENTIFIER_NAMESPACE_VALUE (name);
          if (decl && TREE_CODE (decl) == OVERLOAD)
            decl = OVL_FUNCTION (decl);

          if (decl && decl != error_mark_node
              && (DECL_EXTERNAL (decl) || TREE_PUBLIC (decl))
              /* If different sort of thing, we already gave an error.  */
              && TREE_CODE (decl) == TREE_CODE (x)
              && !same_type_p (TREE_TYPE (x), TREE_TYPE (decl)))
            {
              permerror (input_location, "type mismatch with previous external decl of %q#D", x);
              permerror (input_location, "previous external decl of %q+#D", decl);
            }
        }

      if (TREE_CODE (x) == FUNCTION_DECL
          && is_friend
          && !flag_friend_injection)
        {
          /* This is a new declaration of a friend function, so hide
             it from ordinary function lookup.  */
          DECL_ANTICIPATED (x) = 1;
          DECL_HIDDEN_FRIEND_P (x) = 1;
        }

      /* This name is new in its binding level.
         Install the new declaration and return it.  */
      if (namespace_bindings_p ())
        {
          /* Install a global value.  */

          /* If the first global decl has external linkage,
             warn if we later see static one.  */
          if (IDENTIFIER_GLOBAL_VALUE (name) == NULL_TREE && TREE_PUBLIC (x))
            TREE_PUBLIC (name) = 1;

          /* Bind the name for the entity.  */
          if (!(TREE_CODE (x) == TYPE_DECL && DECL_ARTIFICIAL (x)
                && t != NULL_TREE)
              && (TREE_CODE (x) == TYPE_DECL
                  || TREE_CODE (x) == VAR_DECL
                  || TREE_CODE (x) == NAMESPACE_DECL
                  || TREE_CODE (x) == CONST_DECL
                  || TREE_CODE (x) == TEMPLATE_DECL))
            SET_IDENTIFIER_NAMESPACE_VALUE (name, x);

          /* If new decl is `static' and an `extern' was seen previously,
             warn about it.  */
          if (x != NULL_TREE && t != NULL_TREE && decls_match (x, t))
            warn_extern_redeclared_static (x, t);
        }
      else
        {
          /* Here to install a non-global value.  */
          tree oldglobal = IDENTIFIER_NAMESPACE_VALUE (name);
          tree oldlocal = NULL_TREE;
          cp_binding_level *oldscope = NULL;
          cxx_binding *oldbinding = outer_binding (name, NULL, true);
          if (oldbinding)
            {
              oldlocal = oldbinding->value;
              oldscope = oldbinding->scope;
            }

          if (need_new_binding)
            {
              push_local_binding (name, x, 0);
              /* Because push_local_binding will hook X on to the
                 current_binding_level's name list, we don't want to
                 do that again below.  */
              need_new_binding = 0;
            }

          /* If this is a TYPE_DECL, push it into the type value slot.  */
          if (TREE_CODE (x) == TYPE_DECL)
            set_identifier_type_value (name, x);

          /* Clear out any TYPE_DECL shadowed by a namespace so that
             we won't think this is a type.  The C struct hack doesn't
             go through namespaces.  */
          if (TREE_CODE (x) == NAMESPACE_DECL)
            set_identifier_type_value (name, NULL_TREE);

          if (oldlocal)
            {
              tree d = oldlocal;

              while (oldlocal
                     && TREE_CODE (oldlocal) == VAR_DECL
                     && DECL_DEAD_FOR_LOCAL (oldlocal))
                oldlocal = DECL_SHADOWED_FOR_VAR (oldlocal);

              if (oldlocal == NULL_TREE)
                oldlocal = IDENTIFIER_NAMESPACE_VALUE (DECL_NAME (d));
            }

          /* If this is an extern function declaration, see if we
             have a global definition or declaration for the function.  */
          if (oldlocal == NULL_TREE
              && DECL_EXTERNAL (x)
              && oldglobal != NULL_TREE
              && TREE_CODE (x) == FUNCTION_DECL
              && TREE_CODE (oldglobal) == FUNCTION_DECL)
            {
              /* We have one.  Their types must agree.  */
              if (decls_match (x, oldglobal))
                /* OK */;
              else
                {
                  warning (0, "extern declaration of %q#D doesn%'t match", x);
                  warning (0, "global declaration %q+#D", oldglobal);
                }
            }
          /* If we have a local external declaration,
             and no file-scope declaration has yet been seen,
             then if we later have a file-scope decl it must not be static.  */
          if (oldlocal == NULL_TREE
              && oldglobal == NULL_TREE
              && DECL_EXTERNAL (x)
              && TREE_PUBLIC (x))
            TREE_PUBLIC (name) = 1;

          /* Don't complain about the parms we push and then pop
             while tentatively parsing a function declarator.  */
          if (TREE_CODE (x) == PARM_DECL && DECL_CONTEXT (x) == NULL_TREE)
            /* Ignore.  */;

          /* Warn if shadowing an argument at the top level of the body.  */
          else if (oldlocal != NULL_TREE && !DECL_EXTERNAL (x)
                   /* Inline decls shadow nothing.  */
                   && !DECL_FROM_INLINE (x)
                   && (TREE_CODE (oldlocal) == PARM_DECL
                       || TREE_CODE (oldlocal) == VAR_DECL
                       /* If the old decl is a type decl, only warn if the
                          old decl is an explicit typedef or if both the old
                          and new decls are type decls.  */
                       || (TREE_CODE (oldlocal) == TYPE_DECL
                           && (!DECL_ARTIFICIAL (oldlocal)
                               || TREE_CODE (x) == TYPE_DECL)))
                   /* Don't check for internally generated vars unless
                      it's an implicit typedef (see create_implicit_typedef
                      in decl.c).  */
                   && (!DECL_ARTIFICIAL (x) || DECL_IMPLICIT_TYPEDEF_P (x)))
            {
              bool nowarn = false;

              /* Don't complain if it's from an enclosing function.  */
              if (DECL_CONTEXT (oldlocal) == current_function_decl
                  && TREE_CODE (x) != PARM_DECL
                  && TREE_CODE (oldlocal) == PARM_DECL)
                {
                  /* Go to where the parms should be and see if we find
                     them there.  */
                  cp_binding_level *b = current_binding_level->level_chain;

                  if (FUNCTION_NEEDS_BODY_BLOCK (current_function_decl))
                    /* Skip the ctor/dtor cleanup level.  */
                    b = b->level_chain;

                  /* ARM $8.3 */
                  if (b->kind == sk_function_parms)
                    {
                      error ("declaration of %q#D shadows a parameter", x);
                      nowarn = true;
                    }
                }

              /* The local structure or class can't use parameters of
                 the containing function anyway.  */
              if (DECL_CONTEXT (oldlocal) != current_function_decl)
                {
                  cp_binding_level *scope = current_binding_level;
                  tree context = DECL_CONTEXT (oldlocal);
                  for (; scope; scope = scope->level_chain)
                   {
                     if (scope->kind == sk_function_parms
                         && scope->this_entity == context)
                      break;
                     if (scope->kind == sk_class
                         && !LAMBDA_TYPE_P (scope->this_entity))
                       {
                         nowarn = true;
                         break;
                       }
                   }
                }
              /* Error if redeclaring a local declared in a
                 for-init-statement or in the condition of an if or
                 switch statement when the new declaration is in the
                 outermost block of the controlled statement.
                 Redeclaring a variable from a for or while condition is
                 detected elsewhere.  */
              else if (TREE_CODE (oldlocal) == VAR_DECL
                       && oldscope == current_binding_level->level_chain
                       && (oldscope->kind == sk_cond
                           || oldscope->kind == sk_for))
                {
                  error ("redeclaration of %q#D", x);
                  error ("%q+#D previously declared here", oldlocal);
                }

              if (warn_shadow && !nowarn)
                {
                  if (TREE_CODE (oldlocal) == PARM_DECL)
                    warning_at (input_location, OPT_Wshadow,
                                "declaration of %q#D shadows a parameter", x);
                  else if (is_capture_proxy (oldlocal))
                    warning_at (input_location, OPT_Wshadow,
                                "declaration of %qD shadows a lambda capture",
                                x);
                  else
                    warning_at (input_location, OPT_Wshadow,
                                "declaration of %qD shadows a previous local",
                                x);
                   warning_at (DECL_SOURCE_LOCATION (oldlocal), OPT_Wshadow,
                               "shadowed declaration is here");
                }
            }

          /* Maybe warn if shadowing something else.  */
          else if (warn_shadow && !DECL_EXTERNAL (x)
                   /* No shadow warnings for internally generated vars unless
                      it's an implicit typedef (see create_implicit_typedef
                      in decl.c).  */
                   && (! DECL_ARTIFICIAL (x) || DECL_IMPLICIT_TYPEDEF_P (x))
                   /* No shadow warnings for vars made for inlining.  */
                   && ! DECL_FROM_INLINE (x))
            {
              tree member;

              if (current_class_ptr)
                member = lookup_member (current_class_type,
                                        name,
                                        /*protect=*/0,
                                        /*want_type=*/false,
                                        tf_warning_or_error);
              else
                member = NULL_TREE;

              if (member && !TREE_STATIC (member))
                {
                  /* Location of previous decl is not useful in this case.  */
                  warning (OPT_Wshadow, "declaration of %qD shadows a member of 'this'",
                           x);
                }
              else if (oldglobal != NULL_TREE
                       && (TREE_CODE (oldglobal) == VAR_DECL
                           /* If the old decl is a type decl, only warn if the
                              old decl is an explicit typedef or if both the
                              old and new decls are type decls.  */
                           || (TREE_CODE (oldglobal) == TYPE_DECL
                               && (!DECL_ARTIFICIAL (oldglobal)
                                   || TREE_CODE (x) == TYPE_DECL))))
                /* XXX shadow warnings in outer-more namespaces */
                {
                  warning_at (input_location, OPT_Wshadow,
                              "declaration of %qD shadows a global declaration", x);
                  warning_at (DECL_SOURCE_LOCATION (oldglobal), OPT_Wshadow,
                              "shadowed declaration is here");
                }
            }
        }

      if (TREE_CODE (x) == VAR_DECL)
        maybe_register_incomplete_var (x);
    }

  if (need_new_binding)
    add_decl_to_level (x,
                       DECL_NAMESPACE_SCOPE_P (x)
                       ? NAMESPACE_LEVEL (CP_DECL_CONTEXT (x))
                       : current_binding_level);

  return x;
}

/* Wrapper for pushdecl_maybe_friend_1.  */

tree
pushdecl_maybe_friend (tree x, bool is_friend)
{
  tree ret;
  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  ret = pushdecl_maybe_friend_1 (x, is_friend);
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
  return ret;
}

/* Record a decl-node X as belonging to the current lexical scope.  */

tree
pushdecl (tree x)
{
  return pushdecl_maybe_friend (x, false);
}

/* Enter DECL into the symbol table, if that's appropriate.  Returns
   DECL, or a modified version thereof.  */

tree
maybe_push_decl (tree decl)
{
  tree type = TREE_TYPE (decl);

  /* Add this decl to the current binding level, but not if it comes
     from another scope, e.g. a static member variable.  TEM may equal
     DECL or it may be a previous decl of the same name.  */
  if (decl == error_mark_node
      || (TREE_CODE (decl) != PARM_DECL
          && DECL_CONTEXT (decl) != NULL_TREE
          /* Definitions of namespace members outside their namespace are
             possible.  */
          && !DECL_NAMESPACE_SCOPE_P (decl))
      || (TREE_CODE (decl) == TEMPLATE_DECL && !namespace_bindings_p ())
      || type == unknown_type_node
      /* The declaration of a template specialization does not affect
         the functions available for overload resolution, so we do not
         call pushdecl.  */
      || (TREE_CODE (decl) == FUNCTION_DECL
          && DECL_TEMPLATE_SPECIALIZATION (decl)))
    return decl;
  else
    return pushdecl (decl);
}

/* Bind DECL to ID in the current_binding_level, assumed to be a local
   binding level.  If PUSH_USING is set in FLAGS, we know that DECL
   doesn't really belong to this binding level, that it got here
   through a using-declaration.  */

void
push_local_binding (tree id, tree decl, int flags)
{
  cp_binding_level *b;

  /* Skip over any local classes.  This makes sense if we call
     push_local_binding with a friend decl of a local class.  */
  b = innermost_nonclass_level ();

  if (lookup_name_innermost_nonclass_level (id))
    {
      /* Supplement the existing binding.  */
      if (!supplement_binding (IDENTIFIER_BINDING (id), decl))
        /* It didn't work.  Something else must be bound at this
           level.  Do not add DECL to the list of things to pop
           later.  */
        return;
    }
  else
    /* Create a new binding.  */
    push_binding (id, decl, b);

  if (TREE_CODE (decl) == OVERLOAD || (flags & PUSH_USING))
    /* We must put the OVERLOAD into a TREE_LIST since the
       TREE_CHAIN of an OVERLOAD is already used.  Similarly for
       decls that got here through a using-declaration.  */
    decl = build_tree_list (NULL_TREE, decl);

  /* And put DECL on the list of things declared by the current
     binding level.  */
  add_decl_to_level (decl, b);
}

/* Check to see whether or not DECL is a variable that would have been
   in scope under the ARM, but is not in scope under the ANSI/ISO
   standard.  If so, issue an error message.  If name lookup would
   work in both cases, but return a different result, this function
   returns the result of ANSI/ISO lookup.  Otherwise, it returns
   DECL.  */

tree
check_for_out_of_scope_variable (tree decl)
{
  tree shadowed;

  /* We only care about out of scope variables.  */
  if (!(TREE_CODE (decl) == VAR_DECL && DECL_DEAD_FOR_LOCAL (decl)))
    return decl;

  shadowed = DECL_HAS_SHADOWED_FOR_VAR_P (decl)
    ? DECL_SHADOWED_FOR_VAR (decl) : NULL_TREE ;
  while (shadowed != NULL_TREE && TREE_CODE (shadowed) == VAR_DECL
         && DECL_DEAD_FOR_LOCAL (shadowed))
    shadowed = DECL_HAS_SHADOWED_FOR_VAR_P (shadowed)
      ? DECL_SHADOWED_FOR_VAR (shadowed) : NULL_TREE;
  if (!shadowed)
    shadowed = IDENTIFIER_NAMESPACE_VALUE (DECL_NAME (decl));
  if (shadowed)
    {
      if (!DECL_ERROR_REPORTED (decl))
        {
          warning (0, "name lookup of %qD changed", DECL_NAME (decl));
          warning (0, "  matches this %q+D under ISO standard rules",
                   shadowed);
          warning (0, "  matches this %q+D under old rules", decl);
          DECL_ERROR_REPORTED (decl) = 1;
        }
      return shadowed;
    }

  /* If we have already complained about this declaration, there's no
     need to do it again.  */
  if (DECL_ERROR_REPORTED (decl))
    return decl;

  DECL_ERROR_REPORTED (decl) = 1;

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

  if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (decl)))
    {
      error ("name lookup of %qD changed for ISO %<for%> scoping",
             DECL_NAME (decl));
      error ("  cannot use obsolete binding at %q+D because "
             "it has a destructor", decl);
      return error_mark_node;
    }
  else
    {
      permerror (input_location, "name lookup of %qD changed for ISO %<for%> scoping",
                 DECL_NAME (decl));
      if (flag_permissive)
        permerror (input_location, "  using obsolete binding at %q+D", decl);
      else
        {
          static bool hint;
          if (!hint)
            {
              inform (input_location, "(if you use %<-fpermissive%> G++ will accept your code)");
              hint = true;
            }
        }
    }

  return decl;
}
\f
/* true means unconditionally make a BLOCK for the next level pushed.  */

static bool keep_next_level_flag;

static int binding_depth = 0;

static void
indent (int depth)
{
  int i;

  for (i = 0; i < depth * 2; i++)
    putc (' ', stderr);
}

/* Return a string describing the kind of SCOPE we have.  */
static const char *
cp_binding_level_descriptor (cp_binding_level *scope)
{
  /* The order of this table must match the "scope_kind"
     enumerators.  */
  static const char* scope_kind_names[] = {
    "block-scope",
    "cleanup-scope",
    "try-scope",
    "catch-scope",
    "for-scope",
    "function-parameter-scope",
    "class-scope",
    "namespace-scope",
    "template-parameter-scope",
    "template-explicit-spec-scope"
  };
  const scope_kind kind = scope->explicit_spec_p
    ? sk_template_spec : scope->kind;

  return scope_kind_names[kind];
}

/* Output a debugging information about SCOPE when performing
   ACTION at LINE.  */
static void
cp_binding_level_debug (cp_binding_level *scope, int line, const char *action)
{
  const char *desc = cp_binding_level_descriptor (scope);
  if (scope->this_entity)
    verbatim ("%s %s(%E) %p %d\n", action, desc,
              scope->this_entity, (void *) scope, line);
  else
    verbatim ("%s %s %p %d\n", action, desc, (void *) scope, line);
}

/* Return the estimated initial size of the hashtable of a NAMESPACE
   scope.  */

static inline size_t
namespace_scope_ht_size (tree ns)
{
  tree name = DECL_NAME (ns);

  return name == std_identifier
    ? NAMESPACE_STD_HT_SIZE
    : (name == global_scope_name
       ? GLOBAL_SCOPE_HT_SIZE
       : NAMESPACE_ORDINARY_HT_SIZE);
}

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

static GTY((deletable)) cp_binding_level *free_binding_level;

/* Insert SCOPE as the innermost binding level.  */

void
push_binding_level (cp_binding_level *scope)
{
  /* Add it to the front of currently active scopes stack.  */
  scope->level_chain = current_binding_level;
  current_binding_level = scope;
  keep_next_level_flag = false;

  if (ENABLE_SCOPE_CHECKING)
    {
      scope->binding_depth = binding_depth;
      indent (binding_depth);
      cp_binding_level_debug (scope, input_line, "push");
      binding_depth++;
    }
}

/* Create a new KIND scope and make it the top of the active scopes stack.
   ENTITY is the scope of the associated C++ entity (namespace, class,
   function, C++0x enumeration); it is NULL otherwise.  */

cp_binding_level *
begin_scope (scope_kind kind, tree entity)
{
  cp_binding_level *scope;

  /* Reuse or create a struct for this binding level.  */
  if (!ENABLE_SCOPE_CHECKING && free_binding_level)
    {
      scope = free_binding_level;
      memset (scope, 0, sizeof (cp_binding_level));
      free_binding_level = scope->level_chain;
    }
  else
    scope = ggc_alloc_cleared_cp_binding_level ();

  scope->this_entity = entity;
  scope->more_cleanups_ok = true;
  switch (kind)
    {
    case sk_cleanup:
      scope->keep = true;
      break;

    case sk_template_spec:
      scope->explicit_spec_p = true;
      kind = sk_template_parms;
      /* Fall through.  */
    case sk_template_parms:
    case sk_block:
    case sk_try:
    case sk_catch:
    case sk_for:
    case sk_cond:
    case sk_class:
    case sk_scoped_enum:
    case sk_function_parms:
    case sk_omp:
      scope->keep = keep_next_level_flag;
      break;

    case sk_namespace:
      NAMESPACE_LEVEL (entity) = scope;
      scope->static_decls =
        VEC_alloc (tree, gc,
                   DECL_NAME (entity) == std_identifier
                   || DECL_NAME (entity) == global_scope_name
                   ? 200 : 10);
      break;

    default:
      /* Should not happen.  */
      gcc_unreachable ();
      break;
    }
  scope->kind = kind;

  push_binding_level (scope);

  return scope;
}

/* We're about to leave current scope.  Pop the top of the stack of
   currently active scopes.  Return the enclosing scope, now active.  */

cp_binding_level *
leave_scope (void)
{
  cp_binding_level *scope = current_binding_level;

  if (scope->kind == sk_namespace && class_binding_level)
    current_binding_level = class_binding_level;

  /* We cannot leave a scope, if there are none left.  */
  if (NAMESPACE_LEVEL (global_namespace))
    gcc_assert (!global_scope_p (scope));

  if (ENABLE_SCOPE_CHECKING)
    {
      indent (--binding_depth);
      cp_binding_level_debug (scope, input_line, "leave");
    }

  /* Move one nesting level up.  */
  current_binding_level = scope->level_chain;

  /* Namespace-scopes are left most probably temporarily, not
     completely; they can be reopened later, e.g. in namespace-extension
     or any name binding activity that requires us to resume a
     namespace.  For classes, we cache some binding levels.  For other
     scopes, we just make the structure available for reuse.  */
  if (scope->kind != sk_namespace
      && scope->kind != sk_class)
    {
      scope->level_chain = free_binding_level;
      gcc_assert (!ENABLE_SCOPE_CHECKING
                  || scope->binding_depth == binding_depth);
      free_binding_level = scope;
    }

  /* Find the innermost enclosing class scope, and reset
     CLASS_BINDING_LEVEL appropriately.  */
  if (scope->kind == sk_class)
    {
      class_binding_level = NULL;
      for (scope = current_binding_level; scope; scope = scope->level_chain)
        if (scope->kind == sk_class)
          {
            class_binding_level = scope;
            break;
          }
    }

  return current_binding_level;
}

static void
resume_scope (cp_binding_level* b)
{
  /* Resuming binding levels is meant only for namespaces,
     and those cannot nest into classes.  */
  gcc_assert (!class_binding_level);
  /* Also, resuming a non-directly nested namespace is a no-no.  */
  gcc_assert (b->level_chain == current_binding_level);
  current_binding_level = b;
  if (ENABLE_SCOPE_CHECKING)
    {
      b->binding_depth = binding_depth;
      indent (binding_depth);
      cp_binding_level_debug (b, input_line, "resume");
      binding_depth++;
    }
}

/* Return the innermost binding level that is not for a class scope.  */

static cp_binding_level *
innermost_nonclass_level (void)
{
  cp_binding_level *b;

  b = current_binding_level;
  while (b->kind == sk_class)
    b = b->level_chain;

  return b;
}

/* We're defining an object of type TYPE.  If it needs a cleanup, but
   we're not allowed to add any more objects with cleanups to the current
   scope, create a new binding level.  */

void
maybe_push_cleanup_level (tree type)
{
  if (type != error_mark_node
      && TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
      && current_binding_level->more_cleanups_ok == 0)
    {
      begin_scope (sk_cleanup, NULL);
      current_binding_level->statement_list = push_stmt_list ();
    }
}

/* Return true if we are in the global binding level.  */

bool
global_bindings_p (void)
{
  return global_scope_p (current_binding_level);
}

/* True if we are currently in a toplevel binding level.  This
   means either the global binding level or a namespace in a toplevel
   binding level.  Since there are no non-toplevel namespace levels,
   this really means any namespace or template parameter level.  We
   also include a class whose context is toplevel.  */

bool
toplevel_bindings_p (void)
{
  cp_binding_level *b = innermost_nonclass_level ();

  return b->kind == sk_namespace || b->kind == sk_template_parms;
}

/* True if this is a namespace scope, or if we are defining a class
   which is itself at namespace scope, or whose enclosing class is
   such a class, etc.  */

bool
namespace_bindings_p (void)
{
  cp_binding_level *b = innermost_nonclass_level ();

  return b->kind == sk_namespace;
}

/* True if the innermost non-class scope is a block scope.  */

bool
local_bindings_p (void)
{
  cp_binding_level *b = innermost_nonclass_level ();
  return b->kind < sk_function_parms || b->kind == sk_omp;
}

/* True if the current level needs to have a BLOCK made.  */

bool
kept_level_p (void)
{
  return (current_binding_level->blocks != NULL_TREE
          || current_binding_level->keep
          || current_binding_level->kind == sk_cleanup
          || current_binding_level->names != NULL_TREE
          || current_binding_level->using_directives);
}

/* Returns the kind of the innermost scope.  */

scope_kind
innermost_scope_kind (void)
{
  return current_binding_level->kind;
}

/* Returns true if this scope was created to store template parameters.  */

bool
template_parm_scope_p (void)
{
  return innermost_scope_kind () == sk_template_parms;
}

/* If KEEP is true, make a BLOCK node for the next binding level,
   unconditionally.  Otherwise, use the normal logic to decide whether
   or not to create a BLOCK.  */

void
keep_next_level (bool keep)
{
  keep_next_level_flag = keep;
}

/* Return the list of declarations of the current level.
   Note that this list is in reverse order unless/until
   you nreverse it; and when you do nreverse it, you must
   store the result back using `storedecls' or you will lose.  */

tree
getdecls (void)
{
  return current_binding_level->names;
}

/* Return how many function prototypes we are currently nested inside.  */

int
function_parm_depth (void)
{
  int level = 0;
  cp_binding_level *b;

  for (b = current_binding_level;
       b->kind == sk_function_parms;
       b = b->level_chain)
    ++level;

  return level;
}

/* For debugging.  */
static int no_print_functions = 0;
static int no_print_builtins = 0;

static void
print_binding_level (cp_binding_level* lvl)
{
  tree t;
  int i = 0, len;
  fprintf (stderr, " blocks=%p", (void *) lvl->blocks);
  if (lvl->more_cleanups_ok)
    fprintf (stderr, " more-cleanups-ok");
  if (lvl->have_cleanups)
    fprintf (stderr, " have-cleanups");
  fprintf (stderr, "\n");
  if (lvl->names)
    {
      fprintf (stderr, " names:\t");
      /* We can probably fit 3 names to a line?  */
      for (t = lvl->names; t; t = TREE_CHAIN (t))
        {
          if (no_print_functions && (TREE_CODE (t) == FUNCTION_DECL))
            continue;
          if (no_print_builtins
              && (TREE_CODE (t) == TYPE_DECL)
              && DECL_IS_BUILTIN (t))
            continue;

          /* Function decls tend to have longer names.  */
          if (TREE_CODE (t) == FUNCTION_DECL)
            len = 3;
          else
            len = 2;
          i += len;
          if (i > 6)
            {
              fprintf (stderr, "\n\t");
              i = len;
            }
          print_node_brief (stderr, "", t, 0);
          if (t == error_mark_node)
            break;
        }
      if (i)
        fprintf (stderr, "\n");
    }
  if (VEC_length (cp_class_binding, lvl->class_shadowed))
    {
      size_t i;
      cp_class_binding *b;
      fprintf (stderr, " class-shadowed:");
      FOR_EACH_VEC_ELT (cp_class_binding, lvl->class_shadowed, i, b)
        fprintf (stderr, " %s ", IDENTIFIER_POINTER (b->identifier));
      fprintf (stderr, "\n");
    }
  if (lvl->type_shadowed)
    {
      fprintf (stderr, " type-shadowed:");
      for (t = lvl->type_shadowed; t; t = TREE_CHAIN (t))
        {
          fprintf (stderr, " %s ", IDENTIFIER_POINTER (TREE_PURPOSE (t)));
        }
      fprintf (stderr, "\n");
    }
}

void
print_other_binding_stack (cp_binding_level *stack)
{
  cp_binding_level *level;
  for (level = stack; !global_scope_p (level); level = level->level_chain)
    {
      fprintf (stderr, "binding level %p\n", (void *) level);
      print_binding_level (level);
    }
}

void
print_binding_stack (void)
{
  cp_binding_level *b;
  fprintf (stderr, "current_binding_level=%p\n"
           "class_binding_level=%p\n"
           "NAMESPACE_LEVEL (global_namespace)=%p\n",
           (void *) current_binding_level, (void *) class_binding_level,
           (void *) NAMESPACE_LEVEL (global_namespace));
  if (class_binding_level)
    {
      for (b = class_binding_level; b; b = b->level_chain)
        if (b == current_binding_level)
          break;
      if (b)
        b = class_binding_level;
      else
        b = current_binding_level;
    }
  else
    b = current_binding_level;
  print_other_binding_stack (b);
  fprintf (stderr, "global:\n");
  print_binding_level (NAMESPACE_LEVEL (global_namespace));
}
\f
/* Return the type associated with ID.  */

static tree
identifier_type_value_1 (tree id)
{
  /* There is no type with that name, anywhere.  */
  if (REAL_IDENTIFIER_TYPE_VALUE (id) == NULL_TREE)
    return NULL_TREE;
  /* This is not the type marker, but the real thing.  */
  if (REAL_IDENTIFIER_TYPE_VALUE (id) != global_type_node)
    return REAL_IDENTIFIER_TYPE_VALUE (id);
  /* Have to search for it. It must be on the global level, now.
     Ask lookup_name not to return non-types.  */
  id = lookup_name_real (id, 2, 1, /*block_p=*/true, 0, LOOKUP_COMPLAIN);
  if (id)
    return TREE_TYPE (id);
  return NULL_TREE;
}

/* Wrapper for identifier_type_value_1.  */

tree
identifier_type_value (tree id)
{
  tree ret;
  timevar_start (TV_NAME_LOOKUP);
  ret = identifier_type_value_1 (id);
  timevar_stop (TV_NAME_LOOKUP);
  return ret;
}


/* Return the IDENTIFIER_GLOBAL_VALUE of T, for use in common code, since
   the definition of IDENTIFIER_GLOBAL_VALUE is different for C and C++.  */

tree
identifier_global_value (tree t)
{
  return IDENTIFIER_GLOBAL_VALUE (t);
}

/* Push a definition of struct, union or enum tag named ID.  into
   binding_level B.  DECL is a TYPE_DECL for the type.  We assume that
   the tag ID is not already defined.  */

static void
set_identifier_type_value_with_scope (tree id, tree decl, cp_binding_level *b)
{
  tree type;

  if (b->kind != sk_namespace)
    {
      /* Shadow the marker, not the real thing, so that the marker
         gets restored later.  */
      tree old_type_value = REAL_IDENTIFIER_TYPE_VALUE (id);
      b->type_shadowed
        = tree_cons (id, old_type_value, b->type_shadowed);
      type = decl ? TREE_TYPE (decl) : NULL_TREE;
      TREE_TYPE (b->type_shadowed) = type;
    }
  else
    {
      cxx_binding *binding =
        binding_for_name (NAMESPACE_LEVEL (current_namespace), id);
      gcc_assert (decl);
      if (binding->value)
        supplement_binding (binding, decl);
      else
        binding->value = decl;

      /* Store marker instead of real type.  */
      type = global_type_node;
    }
  SET_IDENTIFIER_TYPE_VALUE (id, type);
}

/* As set_identifier_type_value_with_scope, but using
   current_binding_level.  */

void
set_identifier_type_value (tree id, tree decl)
{
  set_identifier_type_value_with_scope (id, decl, current_binding_level);
}

/* Return the name for the constructor (or destructor) for the
   specified class TYPE.  When given a template, this routine doesn't
   lose the specialization.  */

static inline tree
constructor_name_full (tree type)
{
  return TYPE_IDENTIFIER (TYPE_MAIN_VARIANT (type));
}

/* Return the name for the constructor (or destructor) for the
   specified class.  When given a template, return the plain
   unspecialized name.  */

tree
constructor_name (tree type)
{
  tree name;
  name = constructor_name_full (type);
  if (IDENTIFIER_TEMPLATE (name))
    name = IDENTIFIER_TEMPLATE (name);
  return name;
}

/* Returns TRUE if NAME is the name for the constructor for TYPE,
   which must be a class type.  */

bool
constructor_name_p (tree name, tree type)
{
  tree ctor_name;

  gcc_assert (MAYBE_CLASS_TYPE_P (type));

  if (!name)
    return false;

  if (TREE_CODE (name) != IDENTIFIER_NODE)
    return false;

  ctor_name = constructor_name_full (type);
  if (name == ctor_name)
    return true;
  if (IDENTIFIER_TEMPLATE (ctor_name)
      && name == IDENTIFIER_TEMPLATE (ctor_name))
    return true;
  return false;
}

/* Counter used to create anonymous type names.  */

static GTY(()) int anon_cnt;

/* Return an IDENTIFIER which can be used as a name for
   anonymous structs and unions.  */

tree
make_anon_name (void)
{
  char buf[32];

  sprintf (buf, ANON_AGGRNAME_FORMAT, anon_cnt++);
  return get_identifier (buf);
}

/* This code is practically identical to that for creating
   anonymous names, but is just used for lambdas instead.  This is necessary
   because anonymous names are recognized and cannot be passed to template
   functions.  */
/* FIXME is this still necessary? */

static GTY(()) int lambda_cnt = 0;

tree
make_lambda_name (void)
{
  char buf[32];

  sprintf (buf, LAMBDANAME_FORMAT, lambda_cnt++);
  return get_identifier (buf);
}

/* Return (from the stack of) the BINDING, if any, established at SCOPE.  */

static inline cxx_binding *
find_binding (cp_binding_level *scope, cxx_binding *binding)
{
  for (; binding != NULL; binding = binding->previous)
    if (binding->scope == scope)
      return binding;

  return (cxx_binding *)0;
}

/* Return the binding for NAME in SCOPE, if any.  Otherwise, return NULL.  */

static inline cxx_binding *
cp_binding_level_find_binding_for_name (cp_binding_level *scope, tree name)
{
  cxx_binding *b = IDENTIFIER_NAMESPACE_BINDINGS (name);
  if (b)
    {
      /* Fold-in case where NAME is used only once.  */
      if (scope == b->scope && b->previous == NULL)
        return b;
      return find_binding (scope, b);
    }
  return NULL;
}

/* Always returns a binding for name in scope.  If no binding is
   found, make a new one.  */

static cxx_binding *
binding_for_name (cp_binding_level *scope, tree name)
{
  cxx_binding *result;

  result = cp_binding_level_find_binding_for_name (scope, name);
  if (result)
    return result;
  /* Not found, make a new one.  */
  result = cxx_binding_make (NULL, NULL);
  result->previous = IDENTIFIER_NAMESPACE_BINDINGS (name);
  result->scope = scope;
  result->is_local = false;
  result->value_is_inherited = false;
  IDENTIFIER_NAMESPACE_BINDINGS (name) = result;
  return result;
}

/* Walk through the bindings associated to the name of FUNCTION,
   and return the first declaration of a function with a
   "C" linkage specification, a.k.a 'extern "C"'.
   This function looks for the binding, regardless of which scope it
   has been defined in. It basically looks in all the known scopes.
   Note that this function does not lookup for bindings of builtin functions
   or for functions declared in system headers.  */
static tree
lookup_extern_c_fun_in_all_ns (tree function)
{
  tree name;
  cxx_binding *iter;

  gcc_assert (function && TREE_CODE (function) == FUNCTION_DECL);

  name = DECL_NAME (function);
  gcc_assert (name && TREE_CODE (name) == IDENTIFIER_NODE);

  for (iter = IDENTIFIER_NAMESPACE_BINDINGS (name);
       iter;
       iter = iter->previous)
    {
      tree ovl;
      for (ovl = iter->value; ovl; ovl = OVL_NEXT (ovl))
        {
          tree decl = OVL_CURRENT (ovl);
          if (decl
              && TREE_CODE (decl) == FUNCTION_DECL
              && DECL_EXTERN_C_P (decl)
              && !DECL_ARTIFICIAL (decl))
            {
              return decl;
            }
        }
    }
  return NULL;
}

/* Returns a list of C-linkage decls with the name NAME.  */

tree
c_linkage_bindings (tree name)
{
  tree decls = NULL_TREE;
  cxx_binding *iter;

  for (iter = IDENTIFIER_NAMESPACE_BINDINGS (name);
       iter;
       iter = iter->previous)
    {
      tree ovl;
      for (ovl = iter->value; ovl; ovl = OVL_NEXT (ovl))
        {
          tree decl = OVL_CURRENT (ovl);
          if (decl
              && DECL_EXTERN_C_P (decl)
              && !DECL_ARTIFICIAL (decl))
            {
              if (decls == NULL_TREE)
                decls = decl;
              else
                decls = tree_cons (NULL_TREE, decl, decls);
            }
        }
    }
  return decls;
}

/* Insert another USING_DECL into the current binding level, returning
   this declaration. If this is a redeclaration, do nothing, and
   return NULL_TREE if this not in namespace scope (in namespace
   scope, a using decl might extend any previous bindings).  */

static tree
push_using_decl_1 (tree scope, tree name)
{
  tree decl;

  gcc_assert (TREE_CODE (scope) == NAMESPACE_DECL);
  gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE);
  for (decl = current_binding_level->usings; decl; decl = DECL_CHAIN (decl))
    if (USING_DECL_SCOPE (decl) == scope && DECL_NAME (decl) == name)
      break;
  if (decl)
    return namespace_bindings_p () ? decl : NULL_TREE;
  decl = build_lang_decl (USING_DECL, name, NULL_TREE);
  USING_DECL_SCOPE (decl) = scope;
  DECL_CHAIN (decl) = current_binding_level->usings;
  current_binding_level->usings = decl;
  return decl;
}

/* Wrapper for push_using_decl_1.  */

static tree
push_using_decl (tree scope, tree name)
{
  tree ret;
  timevar_start (TV_NAME_LOOKUP);
  ret = push_using_decl_1 (scope, name);
  timevar_stop (TV_NAME_LOOKUP);
  return ret;
}

/* Same as pushdecl, but define X in binding-level LEVEL.  We rely on the
   caller to set DECL_CONTEXT properly.

   Note that this must only be used when X will be the new innermost
   binding for its name, as we tack it onto the front of IDENTIFIER_BINDING
   without checking to see if the current IDENTIFIER_BINDING comes from a
   closer binding level than LEVEL.  */

static tree
pushdecl_with_scope_1 (tree x, cp_binding_level *level, bool is_friend)
{
  cp_binding_level *b;
  tree function_decl = current_function_decl;

  current_function_decl = NULL_TREE;
  if (level->kind == sk_class)
    {
      b = class_binding_level;
      class_binding_level = level;
      pushdecl_class_level (x);
      class_binding_level = b;
    }
  else
    {
      b = current_binding_level;
      current_binding_level = level;
      x = pushdecl_maybe_friend (x, is_friend);
      current_binding_level = b;
    }
  current_function_decl = function_decl;
  return x;
}
 
/* Wrapper for pushdecl_with_scope_1.  */

tree
pushdecl_with_scope (tree x, cp_binding_level *level, bool is_friend)
{
  tree ret;
  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  ret = pushdecl_with_scope_1 (x, level, is_friend);
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
  return ret;
}


/* DECL is a FUNCTION_DECL for a non-member function, which may have
   other definitions already in place.  We get around this by making
   the value of the identifier point to a list of all the things that
   want to be referenced by that name.  It is then up to the users of
   that name to decide what to do with that list.

   DECL may also be a TEMPLATE_DECL, with a FUNCTION_DECL in its
   DECL_TEMPLATE_RESULT.  It is dealt with the same way.

   FLAGS is a bitwise-or of the following values:
     PUSH_LOCAL: Bind DECL in the current scope, rather than at
                 namespace scope.
     PUSH_USING: DECL is being pushed as the result of a using
                 declaration.

   IS_FRIEND is true if this is a friend declaration.

   The value returned may be a previous declaration if we guessed wrong
   about what language DECL should belong to (C or C++).  Otherwise,
   it's always DECL (and never something that's not a _DECL).  */

static tree
push_overloaded_decl_1 (tree decl, int flags, bool is_friend)
{
  tree name = DECL_NAME (decl);
  tree old;
  tree new_binding;
  int doing_global = (namespace_bindings_p () || !(flags & PUSH_LOCAL));

  if (doing_global)
    old = namespace_binding (name, DECL_CONTEXT (decl));
  else
    old = lookup_name_innermost_nonclass_level (name);

  if (old)
    {
      if (TREE_CODE (old) == TYPE_DECL && DECL_ARTIFICIAL (old))
        {
          tree t = TREE_TYPE (old);
          if (MAYBE_CLASS_TYPE_P (t) && warn_shadow
              && (! DECL_IN_SYSTEM_HEADER (decl)
                  || ! DECL_IN_SYSTEM_HEADER (old)))
            warning (OPT_Wshadow, "%q#D hides constructor for %q#T", decl, t);
          old = NULL_TREE;
        }
      else if (is_overloaded_fn (old))
        {
          tree tmp;

          for (tmp = old; tmp; tmp = OVL_NEXT (tmp))
            {
              tree fn = OVL_CURRENT (tmp);
              tree dup;

              if (TREE_CODE (tmp) == OVERLOAD && OVL_USED (tmp)
                  && !(flags & PUSH_USING)
                  && compparms (TYPE_ARG_TYPES (TREE_TYPE (fn)),
                                TYPE_ARG_TYPES (TREE_TYPE (decl)))
                  && ! decls_match (fn, decl))
                error ("%q#D conflicts with previous using declaration %q#D",
                       decl, fn);

              dup = duplicate_decls (decl, fn, is_friend);
              /* If DECL was a redeclaration of FN -- even an invalid
                 one -- pass that information along to our caller.  */
              if (dup == fn || dup == error_mark_node)
                return dup;
            }

          /* We don't overload implicit built-ins.  duplicate_decls()
             may fail to merge the decls if the new decl is e.g. a
             template function.  */
          if (TREE_CODE (old) == FUNCTION_DECL
              && DECL_ANTICIPATED (old)
              && !DECL_HIDDEN_FRIEND_P (old))
            old = NULL;
        }
      else if (old == error_mark_node)
        /* Ignore the undefined symbol marker.  */
        old = NULL_TREE;
      else
        {
          error ("previous non-function declaration %q+#D", old);
          error ("conflicts with function declaration %q#D", decl);
          return decl;
        }
    }

  if (old || TREE_CODE (decl) == TEMPLATE_DECL
      /* If it's a using declaration, we always need to build an OVERLOAD,
         because it's the only way to remember that the declaration comes
         from 'using', and have the lookup behave correctly.  */
      || (flags & PUSH_USING))
    {
      if (old && TREE_CODE (old) != OVERLOAD)
        new_binding = ovl_cons (decl, ovl_cons (old, NULL_TREE));
      else
        new_binding = ovl_cons (decl, old);
      if (flags & PUSH_USING)
        OVL_USED (new_binding) = 1;
    }
  else
    /* NAME is not ambiguous.  */
    new_binding = decl;

  if (doing_global)
    set_namespace_binding (name, current_namespace, new_binding);
  else
    {
      /* We only create an OVERLOAD if there was a previous binding at
         this level, or if decl is a template. In the former case, we
         need to remove the old binding and replace it with the new
         binding.  We must also run through the NAMES on the binding
         level where the name was bound to update the chain.  */

      if (TREE_CODE (new_binding) == OVERLOAD && old)
        {
          tree *d;

          for (d = &IDENTIFIER_BINDING (name)->scope->names;
               *d;
               d = &TREE_CHAIN (*d))
            if (*d == old
                || (TREE_CODE (*d) == TREE_LIST
                    && TREE_VALUE (*d) == old))
              {
                if (TREE_CODE (*d) == TREE_LIST)
                  /* Just replace the old binding with the new.  */
                  TREE_VALUE (*d) = new_binding;
                else
                  /* Build a TREE_LIST to wrap the OVERLOAD.  */
                  *d = tree_cons (NULL_TREE, new_binding,
                                  TREE_CHAIN (*d));

                /* And update the cxx_binding node.  */
                IDENTIFIER_BINDING (name)->value = new_binding;
                return decl;
              }

          /* We should always find a previous binding in this case.  */
          gcc_unreachable ();
        }

      /* Install the new binding.  */
      push_local_binding (name, new_binding, flags);
    }

  return decl;
}

/* Wrapper for push_overloaded_decl_1.  */

static tree
push_overloaded_decl (tree decl, int flags, bool is_friend)
{
  tree ret;
  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  ret = push_overloaded_decl_1 (decl, flags, is_friend);
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
  return ret;
}

/* Check a non-member using-declaration. Return the name and scope
   being used, and the USING_DECL, or NULL_TREE on failure.  */

static tree
validate_nonmember_using_decl (tree decl, tree scope, tree name)
{
  /* [namespace.udecl]
       A using-declaration for a class member shall be a
       member-declaration.  */
  if (TYPE_P (scope))
    {
      error ("%qT is not a namespace", scope);
      return NULL_TREE;
    }
  else if (scope == error_mark_node)
    return NULL_TREE;

  if (TREE_CODE (decl) == TEMPLATE_ID_EXPR)
    {
      /* 7.3.3/5
           A using-declaration shall not name a template-id.  */
      error ("a using-declaration cannot specify a template-id.  "
             "Try %<using %D%>", name);
      return NULL_TREE;
    }

  if (TREE_CODE (decl) == NAMESPACE_DECL)
    {
      error ("namespace %qD not allowed in using-declaration", decl);
      return NULL_TREE;
    }

  if (TREE_CODE (decl) == SCOPE_REF)
    {
      /* It's a nested name with template parameter dependent scope.
         This can only be using-declaration for class member.  */
      error ("%qT is not a namespace", TREE_OPERAND (decl, 0));
      return NULL_TREE;
    }

  if (is_overloaded_fn (decl))
    decl = get_first_fn (decl);

  gcc_assert (DECL_P (decl));

  /* Make a USING_DECL.  */
  return push_using_decl (scope, name);
}

/* Process local and global using-declarations.  */

static void
do_nonmember_using_decl (tree scope, tree name, tree oldval, tree oldtype,
                         tree *newval, tree *newtype)
{
  struct scope_binding decls = EMPTY_SCOPE_BINDING;

  *newval = *newtype = NULL_TREE;
  if (!qualified_lookup_using_namespace (name, scope, &decls, 0))
    /* Lookup error */
    return;

  if (!decls.value && !decls.type)
    {
      error ("%qD not declared", name);
      return;
    }

  /* Shift the old and new bindings around so we're comparing class and
     enumeration names to each other.  */
  if (oldval && DECL_IMPLICIT_TYPEDEF_P (oldval))
    {
      oldtype = oldval;
      oldval = NULL_TREE;
    }

  if (decls.value && DECL_IMPLICIT_TYPEDEF_P (decls.value))
    {
      decls.type = decls.value;
      decls.value = NULL_TREE;
    }

  /* It is impossible to overload a built-in function; any explicit
     declaration eliminates the built-in declaration.  So, if OLDVAL
     is a built-in, then we can just pretend it isn't there.  */
  if (oldval
      && TREE_CODE (oldval) == FUNCTION_DECL
      && DECL_ANTICIPATED (oldval)
      && !DECL_HIDDEN_FRIEND_P (oldval))
    oldval = NULL_TREE;

  if (decls.value)
    {
      /* Check for using functions.  */
      if (is_overloaded_fn (decls.value))
        {
          tree tmp, tmp1;

          if (oldval && !is_overloaded_fn (oldval))
            {
              error ("%qD is already declared in this scope", name);
              oldval = NULL_TREE;
            }

          *newval = oldval;
          for (tmp = decls.value; tmp; tmp = OVL_NEXT (tmp))
            {
              tree new_fn = OVL_CURRENT (tmp);

              /* [namespace.udecl]

                 If a function declaration in namespace scope or block
                 scope has the same name and the same parameter types as a
                 function introduced by a using declaration the program is
                 ill-formed.  */
              for (tmp1 = oldval; tmp1; tmp1 = OVL_NEXT (tmp1))
                {
                  tree old_fn = OVL_CURRENT (tmp1);

                  if (new_fn == old_fn)
                    /* The function already exists in the current namespace.  */
                    break;
                  else if (OVL_USED (tmp1))
                    continue; /* this is a using decl */
                  else if (compparms (TYPE_ARG_TYPES (TREE_TYPE (new_fn)),
                                      TYPE_ARG_TYPES (TREE_TYPE (old_fn))))
                    {
                      gcc_assert (!DECL_ANTICIPATED (old_fn)
                                  || DECL_HIDDEN_FRIEND_P (old_fn));

                      /* There was already a non-using declaration in
                         this scope with the same parameter types. If both
                         are the same extern "C" functions, that's ok.  */
                      if (decls_match (new_fn, old_fn))
                        break;
                      else
                        {
                          error ("%qD is already declared in this scope", name);
                          break;
                        }
                    }
                }

              /* If we broke out of the loop, there's no reason to add
                 this function to the using declarations for this
                 scope.  */
              if (tmp1)
                continue;

              /* If we are adding to an existing OVERLOAD, then we no
                 longer know the type of the set of functions.  */
              if (*newval && TREE_CODE (*newval) == OVERLOAD)
                TREE_TYPE (*newval) = unknown_type_node;
              /* Add this new function to the set.  */
              *newval = build_overload (OVL_CURRENT (tmp), *newval);
              /* If there is only one function, then we use its type.  (A
                 using-declaration naming a single function can be used in
                 contexts where overload resolution cannot be
                 performed.)  */
              if (TREE_CODE (*newval) != OVERLOAD)
                {
                  *newval = ovl_cons (*newval, NULL_TREE);
                  TREE_TYPE (*newval) = TREE_TYPE (OVL_CURRENT (tmp));
                }
              OVL_USED (*newval) = 1;
            }
        }
      else
        {
          *newval = decls.value;
          if (oldval && !decls_match (*newval, oldval))
            error ("%qD is already declared in this scope", name);
        }
    }
  else
    *newval = oldval;

  if (decls.type && TREE_CODE (decls.type) == TREE_LIST)
    {
      error ("reference to %qD is ambiguous", name);
      print_candidates (decls.type);
    }
  else
    {
      *newtype = decls.type;
      if (oldtype && *newtype && !decls_match (oldtype, *newtype))
        error ("%qD is already declared in this scope", name);
    }

    /* If *newval is empty, shift any class or enumeration name down.  */
    if (!*newval)
      {
        *newval = *newtype;
        *newtype = NULL_TREE;
      }
}

/* Process a using-declaration at function scope.  */

void
do_local_using_decl (tree decl, tree scope, tree name)
{
  tree oldval, oldtype, newval, newtype;
  tree orig_decl = decl;

  decl = validate_nonmember_using_decl (decl, scope, name);
  if (decl == NULL_TREE)
    return;

  if (building_stmt_list_p ()
      && at_function_scope_p ())
    add_decl_expr (decl);

  oldval = lookup_name_innermost_nonclass_level (name);
  oldtype = lookup_type_current_level (name);

  do_nonmember_using_decl (scope, name, oldval, oldtype, &newval, &newtype);

  if (newval)
    {
      if (is_overloaded_fn (newval))
        {
          tree fn, term;

          /* We only need to push declarations for those functions
             that were not already bound in the current level.
             The old value might be NULL_TREE, it might be a single
             function, or an OVERLOAD.  */
          if (oldval && TREE_CODE (oldval) == OVERLOAD)
            term = OVL_FUNCTION (oldval);
          else
            term = oldval;
          for (fn = newval; fn && OVL_CURRENT (fn) != term;
               fn = OVL_NEXT (fn))
            push_overloaded_decl (OVL_CURRENT (fn),
                                  PUSH_LOCAL | PUSH_USING,
                                  false);
        }
      else
        push_local_binding (name, newval, PUSH_USING);
    }
  if (newtype)
    {
      push_local_binding (name, newtype, PUSH_USING);
      set_identifier_type_value (name, newtype);
    }

  /* Emit debug info.  */
  if (!processing_template_decl)
    cp_emit_debug_info_for_using (orig_decl, current_scope());
}

/* Returns true if ROOT (a namespace, class, or function) encloses
   CHILD.  CHILD may be either a class type or a namespace.  */

bool
is_ancestor (tree root, tree child)
{
  gcc_assert ((TREE_CODE (root) == NAMESPACE_DECL
               || TREE_CODE (root) == FUNCTION_DECL
               || CLASS_TYPE_P (root)));
  gcc_assert ((TREE_CODE (child) == NAMESPACE_DECL
               || CLASS_TYPE_P (child)));

  /* The global namespace encloses everything.  */
  if (root == global_namespace)
    return true;

  while (true)
    {
      /* If we've run out of scopes, stop.  */
      if (!child)
        return false;
      /* If we've reached the ROOT, it encloses CHILD.  */
      if (root == child)
        return true;
      /* Go out one level.  */
      if (TYPE_P (child))
        child = TYPE_NAME (child);
      child = DECL_CONTEXT (child);
    }
}

/* Enter the class or namespace scope indicated by T suitable for name
   lookup.  T can be arbitrary scope, not necessary nested inside the
   current scope.  Returns a non-null scope to pop iff pop_scope
   should be called later to exit this scope.  */

tree
push_scope (tree t)
{
  if (TREE_CODE (t) == NAMESPACE_DECL)
    push_decl_namespace (t);
  else if (CLASS_TYPE_P (t))
    {
      if (!at_class_scope_p ()
          || !same_type_p (current_class_type, t))
        push_nested_class (t);
      else
        /* T is the same as the current scope.  There is therefore no
           need to re-enter the scope.  Since we are not actually
           pushing a new scope, our caller should not call
           pop_scope.  */
        t = NULL_TREE;
    }

  return t;
}

/* Leave scope pushed by push_scope.  */

void
pop_scope (tree t)
{
  if (t == NULL_TREE)
    return;
  if (TREE_CODE (t) == NAMESPACE_DECL)
    pop_decl_namespace ();
  else if CLASS_TYPE_P (t)
    pop_nested_class ();
}

/* Subroutine of push_inner_scope.  */

static void
push_inner_scope_r (tree outer, tree inner)
{
  tree prev;

  if (outer == inner
      || (TREE_CODE (inner) != NAMESPACE_DECL && !CLASS_TYPE_P (inner)))
    return;

  prev = CP_DECL_CONTEXT (TREE_CODE (inner) == NAMESPACE_DECL ? inner : TYPE_NAME (inner));
  if (outer != prev)
    push_inner_scope_r (outer, prev);
  if (TREE_CODE (inner) == NAMESPACE_DECL)
    {
      cp_binding_level *save_template_parm = 0;
      /* Temporary take out template parameter scopes.  They are saved
         in reversed order in save_template_parm.  */
      while (current_binding_level->kind == sk_template_parms)
        {
          cp_binding_level *b = current_binding_level;
          current_binding_level = b->level_chain;
          b->level_chain = save_template_parm;
          save_template_parm = b;
        }

      resume_scope (NAMESPACE_LEVEL (inner));
      current_namespace = inner;

      /* Restore template parameter scopes.  */
      while (save_template_parm)
        {
          cp_binding_level *b = save_template_parm;
          save_template_parm = b->level_chain;
          b->level_chain = current_binding_level;
          current_binding_level = b;
        }
    }
  else
    pushclass (inner);
}

/* Enter the scope INNER from current scope.  INNER must be a scope
   nested inside current scope.  This works with both name lookup and
   pushing name into scope.  In case a template parameter scope is present,
   namespace is pushed under the template parameter scope according to
   name lookup rule in 14.6.1/6.

   Return the former current scope suitable for pop_inner_scope.  */

tree
push_inner_scope (tree inner)
{
  tree outer = current_scope ();
  if (!outer)
    outer = current_namespace;

  push_inner_scope_r (outer, inner);
  return outer;
}

/* Exit the current scope INNER back to scope OUTER.  */

void
pop_inner_scope (tree outer, tree inner)
{
  if (outer == inner
      || (TREE_CODE (inner) != NAMESPACE_DECL && !CLASS_TYPE_P (inner)))
    return;

  while (outer != inner)
    {
      if (TREE_CODE (inner) == NAMESPACE_DECL)
        {
          cp_binding_level *save_template_parm = 0;
          /* Temporary take out template parameter scopes.  They are saved
             in reversed order in save_template_parm.  */
          while (current_binding_level->kind == sk_template_parms)
            {
              cp_binding_level *b = current_binding_level;
              current_binding_level = b->level_chain;
              b->level_chain = save_template_parm;
              save_template_parm = b;
            }

          pop_namespace ();

          /* Restore template parameter scopes.  */
          while (save_template_parm)
            {
              cp_binding_level *b = save_template_parm;
              save_template_parm = b->level_chain;
              b->level_chain = current_binding_level;
              current_binding_level = b;
            }
        }
      else
        popclass ();

      inner = CP_DECL_CONTEXT (TREE_CODE (inner) == NAMESPACE_DECL ? inner : TYPE_NAME (inner));
    }
}
\f
/* Do a pushlevel for class declarations.  */

void
pushlevel_class (void)
{
  class_binding_level = begin_scope (sk_class, current_class_type);
}

/* ...and a poplevel for class declarations.  */

void
poplevel_class (void)
{
  cp_binding_level *level = class_binding_level;
  cp_class_binding *cb;
  size_t i;
  tree shadowed;

  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  gcc_assert (level != 0);

  /* If we're leaving a toplevel class, cache its binding level.  */
  if (current_class_depth == 1)
    previous_class_level = level;
  for (shadowed = level->type_shadowed;
       shadowed;
       shadowed = TREE_CHAIN (shadowed))
    SET_IDENTIFIER_TYPE_VALUE (TREE_PURPOSE (shadowed), TREE_VALUE (shadowed));

  /* Remove the bindings for all of the class-level declarations.  */
  if (level->class_shadowed)
    {
      FOR_EACH_VEC_ELT (cp_class_binding, level->class_shadowed, i, cb)
        {
          IDENTIFIER_BINDING (cb->identifier) = cb->base->previous;
          cxx_binding_free (cb->base);
        }
      ggc_free (level->class_shadowed);
      level->class_shadowed = NULL;
    }

  /* Now, pop out of the binding level which we created up in the
     `pushlevel_class' routine.  */
  gcc_assert (current_binding_level == level);
  leave_scope ();
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
}

/* Set INHERITED_VALUE_BINDING_P on BINDING to true or false, as
   appropriate.  DECL is the value to which a name has just been
   bound.  CLASS_TYPE is the class in which the lookup occurred.  */

static void
set_inherited_value_binding_p (cxx_binding *binding, tree decl,
                               tree class_type)
{
  if (binding->value == decl && TREE_CODE (decl) != TREE_LIST)
    {
      tree context;

      if (TREE_CODE (decl) == OVERLOAD)
        context = ovl_scope (decl);
      else
        {
          gcc_assert (DECL_P (decl));
          context = context_for_name_lookup (decl);
        }

      if (is_properly_derived_from (class_type, context))
        INHERITED_VALUE_BINDING_P (binding) = 1;
      else
        INHERITED_VALUE_BINDING_P (binding) = 0;
    }
  else if (binding->value == decl)
    /* We only encounter a TREE_LIST when there is an ambiguity in the
       base classes.  Such an ambiguity can be overridden by a
       definition in this class.  */
    INHERITED_VALUE_BINDING_P (binding) = 1;
  else
    INHERITED_VALUE_BINDING_P (binding) = 0;
}

/* Make the declaration of X appear in CLASS scope.  */

bool
pushdecl_class_level (tree x)
{
  tree name;
  bool is_valid = true;
  bool subtime;

  /* Do nothing if we're adding to an outer lambda closure type,
     outer_binding will add it later if it's needed.  */
  if (current_class_type != class_binding_level->this_entity)
    return true;

  subtime = timevar_cond_start (TV_NAME_LOOKUP);
  /* Get the name of X.  */
  if (TREE_CODE (x) == OVERLOAD)
    name = DECL_NAME (get_first_fn (x));
  else
    name = DECL_NAME (x);

  if (name)
    {
      is_valid = push_class_level_binding (name, x);
      if (TREE_CODE (x) == TYPE_DECL)
        set_identifier_type_value (name, x);
    }
  else if (ANON_AGGR_TYPE_P (TREE_TYPE (x)))
    {
      /* If X is an anonymous aggregate, all of its members are
         treated as if they were members of the class containing the
         aggregate, for naming purposes.  */
      tree f;

      for (f = TYPE_FIELDS (TREE_TYPE (x)); f; f = DECL_CHAIN (f))
        {
          location_t save_location = input_location;
          input_location = DECL_SOURCE_LOCATION (f);
          if (!pushdecl_class_level (f))
            is_valid = false;
          input_location = save_location;
        }
    }
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
  return is_valid;
}

/* Return the BINDING (if any) for NAME in SCOPE, which is a class
   scope.  If the value returned is non-NULL, and the PREVIOUS field
   is not set, callers must set the PREVIOUS field explicitly.  */

static cxx_binding *
get_class_binding (tree name, cp_binding_level *scope)
{
  tree class_type;
  tree type_binding;
  tree value_binding;
  cxx_binding *binding;

  class_type = scope->this_entity;

  /* Get the type binding.  */
  type_binding = lookup_member (class_type, name,
                                /*protect=*/2, /*want_type=*/true,
                                tf_warning_or_error);
  /* Get the value binding.  */
  value_binding = lookup_member (class_type, name,
                                 /*protect=*/2, /*want_type=*/false,
                                 tf_warning_or_error);

  if (value_binding
      && (TREE_CODE (value_binding) == TYPE_DECL
          || DECL_CLASS_TEMPLATE_P (value_binding)
          || (TREE_CODE (value_binding) == TREE_LIST
              && TREE_TYPE (value_binding) == error_mark_node
              && (TREE_CODE (TREE_VALUE (value_binding))
                  == TYPE_DECL))))
    /* We found a type binding, even when looking for a non-type
       binding.  This means that we already processed this binding
       above.  */
    ;
  else if (value_binding)
    {
      if (TREE_CODE (value_binding) == TREE_LIST
          && TREE_TYPE (value_binding) == error_mark_node)
        /* NAME is ambiguous.  */
        ;
      else if (BASELINK_P (value_binding))
        /* NAME is some overloaded functions.  */
        value_binding = BASELINK_FUNCTIONS (value_binding);
    }

  /* If we found either a type binding or a value binding, create a
     new binding object.  */
  if (type_binding || value_binding)
    {
      binding = new_class_binding (name,
                                   value_binding,
                                   type_binding,
                                   scope);
      /* This is a class-scope binding, not a block-scope binding.  */
      LOCAL_BINDING_P (binding) = 0;
      set_inherited_value_binding_p (binding, value_binding, class_type);
    }
  else
    binding = NULL;

  return binding;
}

/* Make the declaration(s) of X appear in CLASS scope under the name
   NAME.  Returns true if the binding is valid.  */

static bool
push_class_level_binding_1 (tree name, tree x)
{
  cxx_binding *binding;
  tree decl = x;
  bool ok;

  /* The class_binding_level will be NULL if x is a template
     parameter name in a member template.  */
  if (!class_binding_level)
    return true;

  if (name == error_mark_node)
    return false;

  /* Check for invalid member names.  */
  gcc_assert (TYPE_BEING_DEFINED (current_class_type));
  /* Check that we're pushing into the right binding level.  */
  gcc_assert (current_class_type == class_binding_level->this_entity);

  /* We could have been passed a tree list if this is an ambiguous
     declaration. If so, pull the declaration out because
     check_template_shadow will not handle a TREE_LIST.  */
  if (TREE_CODE (decl) == TREE_LIST
      && TREE_TYPE (decl) == error_mark_node)
    decl = TREE_VALUE (decl);

  if (!check_template_shadow (decl))
    return false;

  /* [class.mem]

     If T is the name of a class, then each of the following shall
     have a name different from T:

     -- every static data member of class T;

     -- every member of class T that is itself a type;

     -- every enumerator of every member of class T that is an
        enumerated type;

     -- every member of every anonymous union that is a member of
        class T.

     (Non-static data members were also forbidden to have the same
     name as T until TC1.)  */
  if ((TREE_CODE (x) == VAR_DECL
       || TREE_CODE (x) == CONST_DECL
       || (TREE_CODE (x) == TYPE_DECL
           && !DECL_SELF_REFERENCE_P (x))
       /* A data member of an anonymous union.  */
       || (TREE_CODE (x) == FIELD_DECL
           && DECL_CONTEXT (x) != current_class_type))
      && DECL_NAME (x) == constructor_name (current_class_type))
    {
      tree scope = context_for_name_lookup (x);
      if (TYPE_P (scope) && same_type_p (scope, current_class_type))
        {
          error ("%qD has the same name as the class in which it is "
                 "declared",
                 x);
          return false;
        }
    }

  /* Get the current binding for NAME in this class, if any.  */
  binding = IDENTIFIER_BINDING (name);
  if (!binding || binding->scope != class_binding_level)
    {
      binding = get_class_binding (name, class_binding_level);
      /* If a new binding was created, put it at the front of the
         IDENTIFIER_BINDING list.  */
      if (binding)
        {
          binding->previous = IDENTIFIER_BINDING (name);
          IDENTIFIER_BINDING (name) = binding;
        }
    }

  /* If there is already a binding, then we may need to update the
     current value.  */
  if (binding && binding->value)
    {
      tree bval = binding->value;
      tree old_decl = NULL_TREE;
      tree target_decl = strip_using_decl (decl);
      tree target_bval = strip_using_decl (bval);

      if (INHERITED_VALUE_BINDING_P (binding))
        {
          /* If the old binding was from a base class, and was for a
             tag name, slide it over to make room for the new binding.
             The old binding is still visible if explicitly qualified
             with a class-key.  */
          if (TREE_CODE (target_bval) == TYPE_DECL
              && DECL_ARTIFICIAL (target_bval)
              && !(TREE_CODE (target_decl) == TYPE_DECL
                   && DECL_ARTIFICIAL (target_decl)))
            {
              old_decl = binding->type;
              binding->type = bval;
              binding->value = NULL_TREE;
              INHERITED_VALUE_BINDING_P (binding) = 0;
            }
          else
            {
              old_decl = bval;
              /* Any inherited type declaration is hidden by the type
                 declaration in the derived class.  */
              if (TREE_CODE (target_decl) == TYPE_DECL
                  && DECL_ARTIFICIAL (target_decl))
                binding->type = NULL_TREE;
            }
        }
      else if (TREE_CODE (target_decl) == OVERLOAD
               && is_overloaded_fn (target_bval))
        old_decl = bval;
      else if (TREE_CODE (decl) == USING_DECL
               && TREE_CODE (bval) == USING_DECL
               && same_type_p (USING_DECL_SCOPE (decl),
                               USING_DECL_SCOPE (bval)))
        /* This is a using redeclaration that will be diagnosed later
           in supplement_binding */
        ;
      else if (TREE_CODE (decl) == USING_DECL
               && TREE_CODE (bval) == USING_DECL
               && DECL_DEPENDENT_P (decl)
               && DECL_DEPENDENT_P (bval))
        return true;
      else if (TREE_CODE (decl) == USING_DECL
               && is_overloaded_fn (target_bval))
        old_decl = bval;
      else if (TREE_CODE (bval) == USING_DECL
               && is_overloaded_fn (target_decl))
        return true;

      if (old_decl && binding->scope == class_binding_level)
        {
          binding->value = x;
          /* It is always safe to clear INHERITED_VALUE_BINDING_P
             here.  This function is only used to register bindings
             from with the class definition itself.  */
          INHERITED_VALUE_BINDING_P (binding) = 0;
          return true;
        }
    }

  /* Note that we declared this value so that we can issue an error if
     this is an invalid redeclaration of a name already used for some
     other purpose.  */
  note_name_declared_in_class (name, decl);

  /* If we didn't replace an existing binding, put the binding on the
     stack of bindings for the identifier, and update the shadowed
     list.  */
  if (binding && binding->scope == class_binding_level)
    /* Supplement the existing binding.  */
    ok = supplement_binding (binding, decl);
  else
    {
      /* Create a new binding.  */
      push_binding (name, decl, class_binding_level);
      ok = true;
    }

  return ok;
}

/* Wrapper for push_class_level_binding_1.  */

bool
push_class_level_binding (tree name, tree x)
{
  bool ret;
  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  ret = push_class_level_binding_1 (name, x);
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
  return ret;
}

/* Process "using SCOPE::NAME" in a class scope.  Return the
   USING_DECL created.  */

tree
do_class_using_decl (tree scope, tree name)
{
  /* The USING_DECL returned by this function.  */
  tree value;
  /* The declaration (or declarations) name by this using
     declaration.  NULL if we are in a template and cannot figure out
     what has been named.  */
  tree decl;
  /* True if SCOPE is a dependent type.  */
  bool scope_dependent_p;
  /* True if SCOPE::NAME is dependent.  */
  bool name_dependent_p;
  /* True if any of the bases of CURRENT_CLASS_TYPE are dependent.  */
  bool bases_dependent_p;
  tree binfo;
  tree base_binfo;
  int i;

  if (name == error_mark_node)
    return NULL_TREE;

  if (!scope || !TYPE_P (scope))
    {
      error ("using-declaration for non-member at class scope");
      return NULL_TREE;
    }

  /* Make sure the name is not invalid */
  if (TREE_CODE (name) == BIT_NOT_EXPR)
    {
      error ("%<%T::%D%> names destructor", scope, name);
      return NULL_TREE;
    }
  if (MAYBE_CLASS_TYPE_P (scope) && constructor_name_p (name, scope))
    {
      error ("%<%T::%D%> names constructor", scope, name);
      return NULL_TREE;
    }
  if (constructor_name_p (name, current_class_type))
    {
      error ("%<%T::%D%> names constructor in %qT",
             scope, name, current_class_type);
      return NULL_TREE;
    }

  scope_dependent_p = dependent_scope_p (scope);
  name_dependent_p = (scope_dependent_p
                      || (IDENTIFIER_TYPENAME_P (name)
                          && dependent_type_p (TREE_TYPE (name))));

  bases_dependent_p = false;
  if (processing_template_decl)
    for (binfo = TYPE_BINFO (current_class_type), i = 0;
         BINFO_BASE_ITERATE (binfo, i, base_binfo);
         i++)
      if (dependent_type_p (TREE_TYPE (base_binfo)))
        {
          bases_dependent_p = true;
          break;
        }

  decl = NULL_TREE;

  /* From [namespace.udecl]:

       A using-declaration used as a member-declaration shall refer to a
       member of a base class of the class being defined.

     In general, we cannot check this constraint in a template because
     we do not know the entire set of base classes of the current
     class type. Morover, if SCOPE is dependent, it might match a
     non-dependent base.  */

  if (!scope_dependent_p)
    {
      base_kind b_kind;
      binfo = lookup_base (current_class_type, scope, ba_any, &b_kind);
      if (b_kind < bk_proper_base)
        {
          if (!bases_dependent_p)
            {
              error_not_base_type (scope, current_class_type);
              return NULL_TREE;
            }
        }
      else if (!name_dependent_p)
        {
          decl = lookup_member (binfo, name, 0, false, tf_warning_or_error);
          if (!decl)
            {
              error ("no members matching %<%T::%D%> in %q#T", scope, name,
                     scope);
              return NULL_TREE;
            }
          /* The binfo from which the functions came does not matter.  */
          if (BASELINK_P (decl))
            decl = BASELINK_FUNCTIONS (decl);
        }
    }

  value = build_lang_decl (USING_DECL, name, NULL_TREE);
  USING_DECL_DECLS (value) = decl;
  USING_DECL_SCOPE (value) = scope;
  DECL_DEPENDENT_P (value) = !decl;

  return value;
}

\f
/* Return the binding value for name in scope.  */


static tree
namespace_binding_1 (tree name, tree scope)
{
  cxx_binding *binding;

  if (SCOPE_FILE_SCOPE_P (scope))
    scope = global_namespace;
  else
    /* Unnecessary for the global namespace because it can't be an alias. */
    scope = ORIGINAL_NAMESPACE (scope);

  binding = cp_binding_level_find_binding_for_name (NAMESPACE_LEVEL (scope), name);

  return binding ? binding->value : NULL_TREE;
}

tree
namespace_binding (tree name, tree scope)
{
  tree ret;
  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  ret = namespace_binding_1 (name, scope);
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
  return ret;
}

/* Set the binding value for name in scope.  */

static void
set_namespace_binding_1 (tree name, tree scope, tree val)
{
  cxx_binding *b;

  if (scope == NULL_TREE)
    scope = global_namespace;
  b = binding_for_name (NAMESPACE_LEVEL (scope), name);
  if (!b->value || TREE_CODE (val) == OVERLOAD || val == error_mark_node)
    b->value = val;
  else
    supplement_binding (b, val);
}

/* Wrapper for set_namespace_binding_1.  */

void
set_namespace_binding (tree name, tree scope, tree val)
{
  bool subtime = timevar_cond_start (TV_NAME_LOOKUP);
  set_namespace_binding_1 (name, scope, val);
  timevar_cond_stop (TV_NAME_LOOKUP, subtime);
}

/* Set the context of a declaration to scope. Complain if we are not
   outside scope.  */

void
set_decl_namespace (tree decl, tree scope, bool friendp)
{
  tree old;

  /* Get rid of namespace aliases.  */
  scope = ORIGINAL_NAMESPACE (scope);

  /* It is ok for friends to be qualified in parallel space.  */
  if (!friendp && !is_ancestor (current_namespace, scope))
    error ("declaration of %qD not in a namespace surrounding %qD",
           decl, scope);
  DECL_CONTEXT (decl) = FROB_CONTEXT (scope);

  /* Writing "int N::i" to declare a variable within "N" is invalid.  */
  if (scope == current_namespace)
    {
      if (at_namespace_scope_p ())
        error ("explicit qualification in declaration of %qD",
               decl);
      return;
    }

  /* See whether this has been declared in the namespace.  */
  old = lookup_qualified_name (scope, DECL_NAME (decl), false, true);
  if (old == error_mark_node)
    /* No old declaration at all.  */
    goto complain;
  /* If it's a TREE_LIST, the result of the lookup was ambiguous.  */
  if (TREE_CODE (old) == TREE_LIST)
    {
      error ("reference to %qD is ambiguous", decl);
      print_candidates (old);
      return;
    }
  if (!is_overloaded_fn (decl))
    {
      /* We might have found OLD in an inline namespace inside SCOPE.  */
      if (TREE_CODE (decl) == TREE_CODE (old))
        DECL_CONTEXT (decl) = DECL_CONTEXT (old);
      /* Don't compare non-function decls with decls_match here, since
         it can't check for the correct constness at this
         point. pushdecl will find those errors later.  */
      return;
    }
  /* Since decl is a function, old should contain a function decl.  */
  if (!is_overloaded_fn (old))
    goto complain;
  /* A template can be explicitly specialized in any namespace.  */
  if (processing_explicit_instantiation)
    return;
  if (processing_template_decl || processing_specialization)
    /* We have not yet called push_template_decl to turn a
       FUNCTION_DECL into a TEMPLATE_DECL, so the declarations won't
       match.  But, we'll check later, when we construct the
       template.  */
    return;
  /* Instantiations or specializations of templates may be declared as
     friends in any namespace.  */
  if (friendp && DECL_USE_TEMPLATE (decl))
    return;
  if (is_overloaded_fn (old))
    {
      tree found = NULL_TREE;
      tree elt = old;
      for (; elt; elt = OVL_NEXT (elt))
        {
          tree ofn = OVL_CURRENT (elt);
          /* Adjust DECL_CONTEXT first so decls_match will return true
             if DECL will match a declaration in an inline namespace.  */
          DECL_CONTEXT (decl) = DECL_CONTEXT (ofn);
          if (decls_match (decl, ofn))
            {
              if (found && !decls_match (found, ofn))
                {
                  DECL_CONTEXT (decl) = FROB_CONTEXT (scope);
                  error ("reference to %qD is ambiguous", decl);
                  print_candidates (old);
                  return;
                }
              found = ofn;
            }
        }
      if (found)
        {
          if (!is_associated_namespace (scope, CP_DECL_CONTEXT (found)))
            goto complain;
          DECL_CONTEXT (decl) = DECL_CONTEXT (found);
          return;
        }
    }
  else
    {
      DECL_CONTEXT (decl) = DECL_CONTEXT (old);
      if (decls_match (decl, old))
        return;
    }

  /* It didn't work, go back to the explicit scope.  */
  DECL_CONTEXT (decl) = FROB_CONTEXT (scope);
 complain:
  error ("%qD should have been declared inside %qD", decl, scope);
}

/* Return the namespace where the current declaration is declared.  */

tree
current_decl_namespace (void)
{
  tree result;
  /* If we have been pushed into a different namespace, use it.  */
  if (!VEC_empty (tree, decl_namespace_list))
    return VEC_last (tree, decl_namespace_list);

  if (current_class_type)
    result = decl_namespace_context (current_class_type);
  else if (current_function_decl)
    result = decl_namespace_context (current_function_decl);
  else
    result = current_namespace;
  return result;
}