gcc/cp/name-lookup.cc

/* Definitions for C++ name lookup routines.
   Copyright (C) 2003-2022 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"
#define INCLUDE_MEMORY
#include "system.h"
#include "coretypes.h"
#include "cp-tree.h"
#include "timevar.h"
#include "stringpool.h"
#include "print-tree.h"
#include "attribs.h"
#include "debug.h"
#include "c-family/c-pragma.h"
#include "gcc-rich-location.h"
#include "spellcheck-tree.h"
#include "parser.h"
#include "c-family/name-hint.h"
#include "c-family/known-headers.h"
#include "c-family/c-spellcheck.h"
#include "bitmap.h"

static cxx_binding *cxx_binding_make (tree value, tree type);
static cp_binding_level *innermost_nonclass_level (void);
static void set_identifier_type_value_with_scope (tree id, tree decl,
						  cp_binding_level *b);
static name_hint maybe_suggest_missing_std_header (location_t location,
						   tree name);
static name_hint suggest_alternatives_for_1 (location_t location, tree name,
					     bool suggest_misspellings);

/* Slots in BINDING_VECTOR.  */
enum binding_slots
{
 BINDING_SLOT_CURRENT,	/* Slot for current TU.  */
 BINDING_SLOT_GLOBAL,	/* Slot for merged global module. */
 BINDING_SLOT_PARTITION, /* Slot for merged partition entities
			    (optional).  */

 /* Number of always-allocated slots.  */
 BINDING_SLOTS_FIXED = BINDING_SLOT_GLOBAL + 1
};

/* Create an overload suitable for recording an artificial TYPE_DECL
   and another decl.  We use this machanism to implement the struct
   stat hack.  */

#define STAT_HACK_P(N) ((N) && TREE_CODE (N) == OVERLOAD && OVL_LOOKUP_P (N))
#define STAT_TYPE_VISIBLE_P(N) TREE_USED (OVERLOAD_CHECK (N))
#define STAT_TYPE(N) TREE_TYPE (N)
#define STAT_DECL(N) OVL_FUNCTION (N)
#define STAT_VISIBLE(N) OVL_CHAIN (N)
#define MAYBE_STAT_DECL(N) (STAT_HACK_P (N) ? STAT_DECL (N) : N)
#define MAYBE_STAT_TYPE(N) (STAT_HACK_P (N) ? STAT_TYPE (N) : NULL_TREE)

/* When a STAT_HACK_P is true, OVL_USING_P and OVL_EXPORT_P are valid
   and apply to the hacked type.  */

/* For regular (maybe) overloaded functions, we have OVL_HIDDEN_P.
   But we also need to indicate hiddenness on implicit type decls
   (injected friend classes), and (coming soon) decls injected from
   block-scope externs.  It is too awkward to press the existing
   overload marking for that.  If we have a hidden non-function, we
   always create a STAT_HACK, and use these two markers as needed.  */
#define STAT_TYPE_HIDDEN_P(N) OVL_HIDDEN_P (N)
#define STAT_DECL_HIDDEN_P(N) OVL_DEDUP_P (N)

/* Create a STAT_HACK node with DECL as the value binding and TYPE as
   the type binding.  */

static tree
stat_hack (tree decl = NULL_TREE, tree type = NULL_TREE)
{
  tree result = make_node (OVERLOAD);

  /* Mark this as a lookup, so we can tell this is a stat hack.  */
  OVL_LOOKUP_P (result) = true;
  STAT_DECL (result) = decl;
  STAT_TYPE (result) = type;
  return result;
}

/* Create a local binding level for NAME.  */

static cxx_binding *
create_local_binding (cp_binding_level *level, tree name)
{
  cxx_binding *binding = cxx_binding_make (NULL, NULL);

  LOCAL_BINDING_P (binding) = true;
  binding->scope = level;
  binding->previous = IDENTIFIER_BINDING (name);

  IDENTIFIER_BINDING (name) = binding;
  
  return binding;
}

/* Find the binding for NAME in namespace NS.  If CREATE_P is true,
   make an empty binding if there wasn't one.  */

static tree *
find_namespace_slot (tree ns, tree name, bool create_p = false)
{
  tree *slot = DECL_NAMESPACE_BINDINGS (ns)
    ->find_slot_with_hash (name, name ? IDENTIFIER_HASH_VALUE (name) : 0,
			   create_p ? INSERT : NO_INSERT);
  return slot;
}

static tree
find_namespace_value (tree ns, tree name)
{
  tree *b = find_namespace_slot (ns, name);

  return b ? MAYBE_STAT_DECL (*b) : NULL_TREE;
}

/* Look in *SLOT for a the binding of NAME in imported module IX.
   Returns pointer to binding's slot, or NULL if not found.  Does a
   binary search, as this is mainly used for random access during
   importing.  Do not use for the fixed slots.  */

static binding_slot *
search_imported_binding_slot (tree *slot, unsigned ix)
{
  gcc_assert (ix);

  if (!*slot)
    return NULL;

  if (TREE_CODE (*slot) != BINDING_VECTOR)
    return NULL;
  
  unsigned clusters = BINDING_VECTOR_NUM_CLUSTERS (*slot);
  binding_cluster *cluster = BINDING_VECTOR_CLUSTER_BASE (*slot);

  if (BINDING_VECTOR_SLOTS_PER_CLUSTER == BINDING_SLOTS_FIXED)
    {
      clusters--;
      cluster++;
    }

  while (clusters > 1)
    {
      unsigned half = clusters / 2;
      gcc_checking_assert (cluster[half].indices[0].span);
      if (cluster[half].indices[0].base > ix)
	clusters = half;
      else
	{
	  clusters -= half;
	  cluster += half;
	}
    }

  if (clusters)
    /* Is it in this cluster?  */
    for (unsigned off = 0; off != BINDING_VECTOR_SLOTS_PER_CLUSTER; off++)
      {
	if (!cluster->indices[off].span)
	  break;
	if (cluster->indices[off].base > ix)
	  break;

	if (cluster->indices[off].base + cluster->indices[off].span > ix)
	  return &cluster->slots[off];
      }

  return NULL;
}

static void
init_global_partition (binding_cluster *cluster, tree decl)
{
  bool purview = true;

  if (header_module_p ())
    purview = false;
  else if (TREE_PUBLIC (decl)
	   && TREE_CODE (decl) == NAMESPACE_DECL
	   && !DECL_NAMESPACE_ALIAS (decl))
    purview = false;
  else if (!get_originating_module (decl))
    purview = false;

  binding_slot *mslot;
  if (!purview)
    mslot = &cluster[0].slots[BINDING_SLOT_GLOBAL];
  else
    mslot = &cluster[BINDING_SLOT_PARTITION
		     / BINDING_VECTOR_SLOTS_PER_CLUSTER]
      .slots[BINDING_SLOT_PARTITION
	     % BINDING_VECTOR_SLOTS_PER_CLUSTER];

  if (*mslot)
    decl = ovl_make (decl, *mslot);
  *mslot = decl;

  if (TREE_CODE (decl) == CONST_DECL)
    {
      tree type = TREE_TYPE (decl);
      if (TREE_CODE (type) == ENUMERAL_TYPE
	  && IDENTIFIER_ANON_P (DECL_NAME (TYPE_NAME (type)))
	  && decl == TREE_VALUE (TYPE_VALUES (type)))
	/* Anonymous enums are keyed by their first enumerator, put
	   the TYPE_DECL here too.  */
	*mslot = ovl_make (TYPE_NAME (type), *mslot);
    }
}

/* Get the fixed binding slot IX.  Creating the vector if CREATE is
   non-zero.  If CREATE is < 0, make sure there is at least 1 spare
   slot for an import.  (It is an error for CREATE < 0 and the slot to
   already exist.)  */

static tree *
get_fixed_binding_slot (tree *slot, tree name, unsigned ix, int create)
{
  gcc_checking_assert (ix <= BINDING_SLOT_PARTITION);

  /* An assumption is that the fixed slots all reside in one cluster.  */
  gcc_checking_assert (BINDING_VECTOR_SLOTS_PER_CLUSTER >= BINDING_SLOTS_FIXED);

  if (!*slot || TREE_CODE (*slot) != BINDING_VECTOR)
    {
      if (ix == BINDING_SLOT_CURRENT)
	/* The current TU can just use slot directly.  */
	return slot;

      if (!create)
	return NULL;

      /* The partition slot is only needed when we know we're a named
	 module.  */
      bool partition_slot = named_module_p ();
      unsigned want = ((BINDING_SLOTS_FIXED + partition_slot + (create < 0)
			+ BINDING_VECTOR_SLOTS_PER_CLUSTER - 1)
		       / BINDING_VECTOR_SLOTS_PER_CLUSTER);
      tree new_vec = make_binding_vec (name, want);
      BINDING_VECTOR_NUM_CLUSTERS (new_vec) = want;
      binding_cluster *cluster = BINDING_VECTOR_CLUSTER_BASE (new_vec);

      /* Initialize the fixed slots.  */
      for (unsigned jx = BINDING_SLOTS_FIXED; jx--;)
	{
	  cluster[0].indices[jx].base = 0;
	  cluster[0].indices[jx].span = 1;
	  cluster[0].slots[jx] = NULL_TREE;
	}

      if (partition_slot)
	{
	  unsigned off = BINDING_SLOT_PARTITION % BINDING_VECTOR_SLOTS_PER_CLUSTER;
	  unsigned ind = BINDING_SLOT_PARTITION / BINDING_VECTOR_SLOTS_PER_CLUSTER;
	  cluster[ind].indices[off].base = 0;
	  cluster[ind].indices[off].span = 1;
	  cluster[ind].slots[off] = NULL_TREE;
	}

      if (tree orig = *slot)
	{
	  /* Propagate existing value to current slot.  */

	  /* Propagate global & module entities to the global and
	     partition slots.  */
	  if (tree type = MAYBE_STAT_TYPE (orig))
	    init_global_partition (cluster, type);

	  for (ovl_iterator iter (MAYBE_STAT_DECL (orig)); iter; ++iter)
	    {
	      tree decl = *iter;

	      /* Internal linkage entities are in deduplicateable.  */
	      init_global_partition (cluster, decl);
	    }

	  if (cluster[0].slots[BINDING_SLOT_GLOBAL]
	      && !(TREE_CODE (orig) == NAMESPACE_DECL
		   && !DECL_NAMESPACE_ALIAS (orig)))
	    {
	      /* Note that we had some GMF entries.  */
	      if (!STAT_HACK_P (orig))
		orig = stat_hack (orig);

	      MODULE_BINDING_GLOBAL_P (orig) = true;
	    }

	  cluster[0].slots[BINDING_SLOT_CURRENT] = orig;
	}

      *slot = new_vec;
    }
  else
    gcc_checking_assert (create >= 0);

  unsigned off = ix % BINDING_VECTOR_SLOTS_PER_CLUSTER;
  binding_cluster &cluster
    = BINDING_VECTOR_CLUSTER (*slot, ix / BINDING_VECTOR_SLOTS_PER_CLUSTER);

  /* There must always be slots for these indices  */
  gcc_checking_assert (cluster.indices[off].span == 1
		       && !cluster.indices[off].base
		       && !cluster.slots[off].is_lazy ());

  return reinterpret_cast<tree *> (&cluster.slots[off]);
}

/* *SLOT is a namespace binding slot.  Append a slot for imported
   module IX.  */

static binding_slot *
append_imported_binding_slot (tree *slot, tree name, unsigned ix)
{
  gcc_checking_assert (ix);

  if (!*slot ||  TREE_CODE (*slot) != BINDING_VECTOR)
    /* Make an initial module vector.  */
    get_fixed_binding_slot (slot, name, BINDING_SLOT_GLOBAL, -1);
  else if (!BINDING_VECTOR_CLUSTER_LAST (*slot)
	   ->indices[BINDING_VECTOR_SLOTS_PER_CLUSTER - 1].span)
    /* There is space in the last cluster.  */;
  else if (BINDING_VECTOR_NUM_CLUSTERS (*slot)
	   != BINDING_VECTOR_ALLOC_CLUSTERS (*slot))
    /* There is space in the vector.  */
    BINDING_VECTOR_NUM_CLUSTERS (*slot)++;
  else
    {
      /* Extend the vector.  */
      unsigned have = BINDING_VECTOR_NUM_CLUSTERS (*slot);
      unsigned want = (have * 3 + 1) / 2;

      if (want > (unsigned short)~0)
	want = (unsigned short)~0;

      tree new_vec = make_binding_vec (name, want);
      BINDING_VECTOR_NUM_CLUSTERS (new_vec) = have + 1;
      memcpy (BINDING_VECTOR_CLUSTER_BASE (new_vec),
	      BINDING_VECTOR_CLUSTER_BASE (*slot),
	      have * sizeof (binding_cluster));
      *slot = new_vec;
    }

  binding_cluster *last = BINDING_VECTOR_CLUSTER_LAST (*slot);
  for (unsigned off = 0; off != BINDING_VECTOR_SLOTS_PER_CLUSTER; off++)
    if (!last->indices[off].span)
      {
	/* Fill the free slot of the cluster.  */
	last->indices[off].base = ix;
	last->indices[off].span = 1;
	last->slots[off] = NULL_TREE;
	/* Check monotonicity.  */
	gcc_checking_assert (last[off ? 0 : -1]
			     .indices[off ? off - 1
				      : BINDING_VECTOR_SLOTS_PER_CLUSTER - 1]
			     .base < ix);
	return &last->slots[off];
      }

  gcc_unreachable ();
}

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

static void
add_decl_to_level (cp_binding_level *b, tree decl)
{
  gcc_assert (b->kind != sk_class);

  /* Make sure we don't create a circular list.  xref_tag can end
     up pushing the same artificial decl more than once.  We
     should have already detected that in update_binding.  (This isn't a
     complete verification of non-circularity.)  */
  gcc_assert (b->names != decl);

  /* 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
      && ((VAR_P (decl) && (TREE_STATIC (decl) || DECL_EXTERNAL (decl)))
	  || (TREE_CODE (decl) == FUNCTION_DECL
	      && (!TREE_PUBLIC (decl)
		  || decl_anon_ns_mem_p (decl)
		  || DECL_DECLARED_INLINE_P (decl)))))
    vec_safe_push (static_decls, decl);
}

/* Find the binding for NAME in the local binding level B.  */

static cxx_binding *
find_local_binding (cp_binding_level *b, tree name)
{
  if (cxx_binding *binding = IDENTIFIER_BINDING (name))
    for (;; b = b->level_chain)
      {
	if (binding->scope == b)
	  return binding;

	/* Cleanup contours are transparent to the language.  */
	if (b->kind != sk_cleanup)
	  break;
      }
  return NULL;
}

class name_lookup
{
public:
  typedef std::pair<tree, tree> using_pair;
  typedef auto_vec<using_pair, 16> using_queue;

public:
  tree name;	/* The identifier being looked for.  */

  /* Usually we just add things to the VALUE binding, but we record
     (hidden) IMPLICIT_TYPEDEFs on the type binding, which is used for
     using-decl resolution.  */
  tree value;	/* A (possibly ambiguous) set of things found.  */
  tree type;	/* A type that has been found.  */

  LOOK_want want;  /* What kind of entity we want.  */

  bool deduping; /* Full deduping is needed because using declarations
		    are in play.  */
  vec<tree, va_heap, vl_embed> *scopes;
  name_lookup *previous; /* Previously active lookup.  */

protected:
  /* Marked scope stack for outermost name lookup.  */
  static vec<tree, va_heap, vl_embed> *shared_scopes;
  /* Currently active lookup.  */
  static name_lookup *active;

public:
  name_lookup (tree n, LOOK_want w = LOOK_want::NORMAL)
  : name (n), value (NULL_TREE), type (NULL_TREE),
    want (w),
    deduping (false), scopes (NULL), previous (NULL)
  {
    preserve_state ();
  }
  ~name_lookup ()
  {
    gcc_checking_assert (!deduping);
    restore_state ();
  }

private: /* Uncopyable, unmovable, unassignable. I am a rock. */
  name_lookup (const name_lookup &);
  name_lookup &operator= (const name_lookup &);

 public:
  /* Turn on or off deduping mode.  */
  void dedup (bool state)
  {
    if (deduping != state)
      {
	deduping = state;
	lookup_mark (value, state);
      }
  }

protected:
  static bool seen_p (tree scope)
  {
    return LOOKUP_SEEN_P (scope);
  }
  static bool found_p (tree scope)
  {
    return LOOKUP_FOUND_P (scope);
  }
  
  void mark_seen (tree scope); /* Mark and add to scope vector. */
  static void mark_found (tree scope)
  {
    gcc_checking_assert (seen_p (scope));
    LOOKUP_FOUND_P (scope) = true;
  }
  bool see_and_mark (tree scope)
  {
    bool ret = seen_p (scope);
    if (!ret)
      mark_seen (scope);
    return ret;
  }
  bool find_and_mark (tree scope);

private:
  void preserve_state ();
  void restore_state ();

private:
  static tree ambiguous (tree thing, tree current);
  void add_overload (tree fns);
  void add_value (tree new_val);
  void add_type (tree new_type);
  bool process_binding (tree val_bind, tree type_bind);
  unsigned process_module_binding (tree val_bind, tree type_bind, unsigned);
  /* Look in only namespace.  */
  bool search_namespace_only (tree scope);
  /* Look in namespace and its (recursive) inlines. Ignore using
     directives.  Return true if something found (inc dups). */
  bool search_namespace (tree scope);
  /* Look in the using directives of namespace + inlines using
     qualified lookup rules.  */
  bool search_usings (tree scope);

private:
  void queue_namespace (using_queue& queue, int depth, tree scope);
  void queue_usings (using_queue& queue, int depth, vec<tree, va_gc> *usings);

private:
  void add_fns (tree);

 private:
  void adl_expr (tree);
  void adl_type (tree);
  void adl_template_arg (tree);
  void adl_class (tree);
  void adl_enum (tree);
  void adl_bases (tree);
  void adl_class_only (tree);
  void adl_namespace (tree);
  void adl_class_fns (tree);
  void adl_namespace_fns (tree, bitmap);

public:
  /* Search namespace + inlines + maybe usings as qualified lookup.  */
  bool search_qualified (tree scope, bool usings = true);

  /* Search namespace + inlines + usings as unqualified lookup.  */
  bool search_unqualified (tree scope, cp_binding_level *);

  /* ADL lookup of ARGS.  */
  tree search_adl (tree fns, vec<tree, va_gc> *args);
};

/* Scope stack shared by all outermost lookups.  This avoids us
   allocating and freeing on every single lookup.  */
vec<tree, va_heap, vl_embed> *name_lookup::shared_scopes;

/* Currently active lookup.  */
name_lookup *name_lookup::active;

/* Name lookup is recursive, becase ADL can cause template
   instatiation.  This is of course a rare event, so we optimize for
   it not happening.  When we discover an active name-lookup, which
   must be an ADL lookup,  we need to unmark the marked scopes and also
   unmark the lookup we might have been accumulating.  */

void
name_lookup::preserve_state ()
{
  previous = active;
  if (previous)
    {
      unsigned length = vec_safe_length (previous->scopes);
      vec_safe_reserve (previous->scopes, length * 2);
      for (unsigned ix = length; ix--;)
	{
	  tree decl = (*previous->scopes)[ix];

	  gcc_checking_assert (LOOKUP_SEEN_P (decl));
	  LOOKUP_SEEN_P (decl) = false;

	  /* Preserve the FOUND_P state on the interrupted lookup's
	     stack.  */
	  if (LOOKUP_FOUND_P (decl))
	    {
	      LOOKUP_FOUND_P (decl) = false;
	      previous->scopes->quick_push (decl);
	    }
	}

      /* Unmark the outer partial lookup.  */
      if (previous->deduping)
	lookup_mark (previous->value, false);
    }
  else
    scopes = shared_scopes;
  active = this;
}

/* Restore the marking state of a lookup we interrupted.  */

void
name_lookup::restore_state ()
{
  gcc_checking_assert (!deduping);

  /* Unmark and empty this lookup's scope stack.  */
  for (unsigned ix = vec_safe_length (scopes); ix--;)
    {
      tree decl = scopes->pop ();
      gcc_checking_assert (LOOKUP_SEEN_P (decl));
      LOOKUP_SEEN_P (decl) = false;
      LOOKUP_FOUND_P (decl) = false;
    }

  active = previous;
  if (previous)
    {
      free (scopes);

      unsigned length = vec_safe_length (previous->scopes);
      for (unsigned ix = 0; ix != length; ix++)
	{
	  tree decl = (*previous->scopes)[ix];
	  if (LOOKUP_SEEN_P (decl))
	    {
	      /* The remainder of the scope stack must be recording
		 FOUND_P decls, which we want to pop off.  */
	      do
		{
		  tree decl = previous->scopes->pop ();
		  gcc_checking_assert (LOOKUP_SEEN_P (decl)
				       && !LOOKUP_FOUND_P (decl));
		  LOOKUP_FOUND_P (decl) = true;
		}
	      while (++ix != length);
	      break;
	    }

	  gcc_checking_assert (!LOOKUP_FOUND_P (decl));
	  LOOKUP_SEEN_P (decl) = true;
	}

      /* Remark the outer partial lookup.  */
      if (previous->deduping)
	lookup_mark (previous->value, true);
    }
  else
    shared_scopes = scopes;
}

void
name_lookup::mark_seen (tree scope)
{
  gcc_checking_assert (!seen_p (scope));
  LOOKUP_SEEN_P (scope) = true;
  vec_safe_push (scopes, scope);
}

bool
name_lookup::find_and_mark (tree scope)
{
  bool result = LOOKUP_FOUND_P (scope);
  if (!result)
    {
      LOOKUP_FOUND_P (scope) = true;
      if (!LOOKUP_SEEN_P (scope))
	vec_safe_push (scopes, scope);
    }

  return result;
}

/* THING and CURRENT are ambiguous, concatenate them.  */

tree
name_lookup::ambiguous (tree thing, tree current)
{
  if (TREE_CODE (current) != TREE_LIST)
    {
      current = build_tree_list (NULL_TREE, current);
      TREE_TYPE (current) = error_mark_node;
    }
  current = tree_cons (NULL_TREE, thing, current);
  TREE_TYPE (current) = error_mark_node;

  return current;
}

/* FNS is a new overload set to add to the exising set.  */

void
name_lookup::add_overload (tree fns)
{
  if (!deduping && TREE_CODE (fns) == OVERLOAD)
    {
      tree probe = fns;
      if (!bool (want & LOOK_want::HIDDEN_FRIEND))
	probe = ovl_skip_hidden (probe);
      if (probe && TREE_CODE (probe) == OVERLOAD
	  && OVL_DEDUP_P (probe))
	/* We're about to add something found by multiple paths, so need to
	   engage deduping mode.  */
	dedup (true);
    }

  value = lookup_maybe_add (fns, value, deduping);
}

/* Add a NEW_VAL, a found value binding into the current value binding.  */

void
name_lookup::add_value (tree new_val)
{
  if (OVL_P (new_val) && (!value || OVL_P (value)))
    add_overload (new_val);
  else if (!value)
    value = new_val;
  else if (value == new_val)
    ;
  else if ((TREE_CODE (value) == TYPE_DECL
	    && TREE_CODE (new_val) == TYPE_DECL
	    && same_type_p (TREE_TYPE (value), TREE_TYPE (new_val))))
    /* Typedefs to the same type. */;
  else if (TREE_CODE (value) == NAMESPACE_DECL
	   && TREE_CODE (new_val) == NAMESPACE_DECL
	   && ORIGINAL_NAMESPACE (value) == ORIGINAL_NAMESPACE (new_val))
    /* Namespace (possibly aliased) to the same namespace.  Locate
       the namespace*/
    value = ORIGINAL_NAMESPACE (value);
  else
    {
      /* Disengage deduping mode.  */
      dedup (false);
      value = ambiguous (new_val, value);
    }
}

/* Add a NEW_TYPE, a found type binding into the current type binding.  */

void
name_lookup::add_type (tree new_type)
{
  if (!type)
    type = new_type;
  else if (TREE_CODE (type) == TREE_LIST
	   || !same_type_p (TREE_TYPE (type), TREE_TYPE (new_type)))
    type = ambiguous (new_type, type);
}

/* Process a found binding containing NEW_VAL and NEW_TYPE.  Returns
   true if we actually found something noteworthy.  Hiddenness has
   already been handled in the caller.  */

bool
name_lookup::process_binding (tree new_val, tree new_type)
{
  /* Did we really see a type? */
  if (new_type
      && (want & LOOK_want::TYPE_NAMESPACE) == LOOK_want::NAMESPACE)
    new_type = NULL_TREE;

  /* Do we really see a value? */
  if (new_val)
    switch (TREE_CODE (new_val))
      {
      case TEMPLATE_DECL:
	/* If we expect types or namespaces, and not templates,
	   or this is not a template class.  */
	if (bool (want & LOOK_want::TYPE_NAMESPACE)
	    && !DECL_TYPE_TEMPLATE_P (new_val))
	  new_val = NULL_TREE;
	break;
      case TYPE_DECL:
	if ((want & LOOK_want::TYPE_NAMESPACE) == LOOK_want::NAMESPACE
	    || (new_type && bool (want & LOOK_want::TYPE)))
	  new_val = NULL_TREE;
	break;
      case NAMESPACE_DECL:
	if ((want & LOOK_want::TYPE_NAMESPACE) == LOOK_want::TYPE)
	  new_val = NULL_TREE;
	break;
      default:
	if (bool (want & LOOK_want::TYPE_NAMESPACE))
	  new_val = NULL_TREE;
      }

  if (!new_val)
    {
      new_val = new_type;
      new_type = NULL_TREE;
    }

  /* Merge into the lookup  */
  if (new_val)
    add_value (new_val);
  if (new_type)
    add_type (new_type);

  return new_val != NULL_TREE;
}

/* If we're importing a module containing this binding, add it to the
   lookup set.  The trickiness is with namespaces, we only want to
   find it once.  */

unsigned
name_lookup::process_module_binding (tree new_val, tree new_type,
				     unsigned marker)
{
  /* Optimize for (re-)finding a public namespace.  We only need to
     look once.  */
  if (new_val && !new_type
      && TREE_CODE (new_val) == NAMESPACE_DECL
      && TREE_PUBLIC (new_val)
      && !DECL_NAMESPACE_ALIAS (new_val))
    {
      if (marker & 2)
	return marker;
      marker |= 2;
    }

  if (new_type || new_val)
    marker |= process_binding (new_val, new_type);

  return marker;
}

/* Look in exactly namespace SCOPE.  */

bool
name_lookup::search_namespace_only (tree scope)
{
  bool found = false;
  if (tree *binding = find_namespace_slot (scope, name))
    {
      tree val = *binding;
      if (TREE_CODE (val) == BINDING_VECTOR)
	{
	  /* I presume the binding list is going to be sparser than
	     the import bitmap.  Hence iterate over the former
	     checking for bits set in the bitmap.  */
	  bitmap imports = get_import_bitmap ();
	  binding_cluster *cluster = BINDING_VECTOR_CLUSTER_BASE (val);
	  int marker = 0;
	  int dup_detect = 0;

	  if (tree bind = cluster->slots[BINDING_SLOT_CURRENT])
	    {
	      if (!deduping)
		{
		  if (named_module_purview_p ())
		    {
		      dup_detect |= 2;

		      if (STAT_HACK_P (bind) && MODULE_BINDING_GLOBAL_P (bind))
			dup_detect |= 1;
		    }
		  else
		    dup_detect |= 1;
		}
	      tree type = NULL_TREE;
	      tree value = bind;

	      if (STAT_HACK_P (bind))
		{
		  type = STAT_TYPE (bind);
		  value = STAT_DECL (bind);

		  if (!bool (want & LOOK_want::HIDDEN_FRIEND))
		    {
		      if (STAT_TYPE_HIDDEN_P (bind))
			type = NULL_TREE;
		      if (STAT_DECL_HIDDEN_P (bind))
			value = NULL_TREE;
		      else
			value = ovl_skip_hidden (value);
		    }
		}
	      else if (!bool (want & LOOK_want::HIDDEN_FRIEND))
		value = ovl_skip_hidden (value);

	      marker = process_module_binding (value, type, marker);
	    }

	  /* Scan the imported bindings.  */
	  unsigned ix = BINDING_VECTOR_NUM_CLUSTERS (val);
	  if (BINDING_VECTOR_SLOTS_PER_CLUSTER == BINDING_SLOTS_FIXED)
	    {
	      ix--;
	      cluster++;
	    }

	  /* Do this in forward order, so we load modules in an order
	     the user expects.  */
	  for (; ix--; cluster++)
	    for (unsigned jx = 0; jx != BINDING_VECTOR_SLOTS_PER_CLUSTER; jx++)
	      {
		/* Are we importing this module?  */
		if (unsigned base = cluster->indices[jx].base)
		  if (unsigned span = cluster->indices[jx].span)
		    do
		      if (bitmap_bit_p (imports, base))
			goto found;
		    while (++base, --span);
		continue;

	      found:;
		/* Is it loaded?  */
		if (cluster->slots[jx].is_lazy ())
		  {
		    gcc_assert (cluster->indices[jx].span == 1);
		    lazy_load_binding (cluster->indices[jx].base,
				       scope, name, &cluster->slots[jx]);
		  }
		tree bind = cluster->slots[jx];
		if (!bind)
		  /* Load errors could mean there's nothing here.  */
		  continue;

		/* Extract what we can see from here.  If there's no
		   stat_hack, then everything was exported.  */
		tree type = NULL_TREE;


		/* If STAT_HACK_P is false, everything is visible, and
		   there's no duplication possibilities.  */
		if (STAT_HACK_P (bind))
		  {
		    if (!deduping)
		      {
			/* Do we need to engage deduplication?  */
			int dup = 0;
			if (MODULE_BINDING_GLOBAL_P (bind))
			  dup = 1;
			else if (MODULE_BINDING_PARTITION_P (bind))
			  dup = 2;
			if (unsigned hit = dup_detect & dup)
			  {
			    if ((hit & 1 && BINDING_VECTOR_GLOBAL_DUPS_P (val))
				|| (hit & 2
				    && BINDING_VECTOR_PARTITION_DUPS_P (val)))
			      dedup (true);
			  }
			dup_detect |= dup;
		      }

		    if (STAT_TYPE_VISIBLE_P (bind))
		      type = STAT_TYPE (bind);
		    bind = STAT_VISIBLE (bind);
		  }

		/* And process it.  */
		marker = process_module_binding (bind, type, marker);
	      }
	  found |= marker & 1;
	}
      else
	{
	  /* Only a current module binding, visible from the current module.  */
	  tree bind = *binding;
	  tree value = bind, type = NULL_TREE;

	  if (STAT_HACK_P (bind))
	    {
	      type = STAT_TYPE (bind);
	      value = STAT_DECL (bind);

	      if (!bool (want & LOOK_want::HIDDEN_FRIEND))
		{
		  if (STAT_TYPE_HIDDEN_P (bind))
		    type = NULL_TREE;
		  if (STAT_DECL_HIDDEN_P (bind))
		    value = NULL_TREE;
		  else
		    value = ovl_skip_hidden (value);
		}
	    }
	  else if (!bool (want & LOOK_want::HIDDEN_FRIEND))
	    value = ovl_skip_hidden (value);

	  found |= process_binding (value, type);
	}
    }

  return found;
}

/* Conditionally look in namespace SCOPE and inline children.  */

bool
name_lookup::search_namespace (tree scope)
{
  if (see_and_mark (scope))
    /* We've visited this scope before.  Return what we found then.  */
    return found_p (scope);

  /* Look in exactly namespace. */
  bool found = search_namespace_only (scope);

  /* Don't look into inline children, if we're looking for an
     anonymous name -- it must be in the current scope, if anywhere.  */
  if (name)
    /* Recursively look in its inline children.  */
    if (vec<tree, va_gc> *inlinees = DECL_NAMESPACE_INLINEES (scope))
      for (unsigned ix = inlinees->length (); ix--;)
	found |= search_namespace ((*inlinees)[ix]);

  if (found)
    mark_found (scope);

  return found;
}

/* Recursively follow using directives of SCOPE & its inline children.
   Such following is essentially a flood-fill algorithm.  */

bool
name_lookup::search_usings (tree scope)
{
  /* We do not check seen_p here, as that was already set during the
     namespace_only walk.  */
  if (found_p (scope))
    return true;

  bool found = false;
  if (vec<tree, va_gc> *usings = NAMESPACE_LEVEL (scope)->using_directives)
    for (unsigned ix = usings->length (); ix--;)
      found |= search_qualified ((*usings)[ix], true);

  /* Look in its inline children.  */
  if (vec<tree, va_gc> *inlinees = DECL_NAMESPACE_INLINEES (scope))
    for (unsigned ix = inlinees->length (); ix--;)
      found |= search_usings ((*inlinees)[ix]);

  if (found)
    mark_found (scope);

  return found;
}

/* Qualified namespace lookup in SCOPE.
   1) Look in SCOPE (+inlines).  If found, we're done.
   2) Otherwise, if USINGS is true,
      recurse for every using directive of SCOPE (+inlines).

   Trickiness is (a) loops and (b) multiple paths to same namespace.
   In both cases we want to not repeat any lookups, and know whether
   to stop the caller's step #2.  Do this via the FOUND_P marker.  */

bool
name_lookup::search_qualified (tree scope, bool usings)
{
  bool found = false;

  if (seen_p (scope))
    found = found_p (scope);
  else 
    {
      found = search_namespace (scope);
      if (!found && usings)
	found = search_usings (scope);
    }

  dedup (false);

  return found;
}

/* Add SCOPE to the unqualified search queue, recursively add its
   inlines and those via using directives.  */

void
name_lookup::queue_namespace (using_queue& queue, int depth, tree scope)
{
  if (see_and_mark (scope))
    return;

  /* Record it.  */
  tree common = scope;
  while (SCOPE_DEPTH (common) > depth)
    common = CP_DECL_CONTEXT (common);
  queue.safe_push (using_pair (common, scope));

  /* Queue its inline children.  */
  if (vec<tree, va_gc> *inlinees = DECL_NAMESPACE_INLINEES (scope))
    for (unsigned ix = inlinees->length (); ix--;)
      queue_namespace (queue, depth, (*inlinees)[ix]);

  /* Queue its using targets.  */
  queue_usings (queue, depth, NAMESPACE_LEVEL (scope)->using_directives);
}

/* Add the namespaces in USINGS to the unqualified search queue.  */

void
name_lookup::queue_usings (using_queue& queue, int depth, vec<tree, va_gc> *usings)
{
  if (usings)
    for (unsigned ix = usings->length (); ix--;)
      queue_namespace (queue, depth, (*usings)[ix]);
}

/* Unqualified namespace lookup in SCOPE.
   1) add scope+inlins to worklist.
   2) recursively add target of every using directive
   3) for each worklist item where SCOPE is common ancestor, search it
   4) if nothing find, scope=parent, goto 1.  */

bool
name_lookup::search_unqualified (tree scope, cp_binding_level *level)
{
  using_queue queue;
  bool found = false;

  /* Queue local using-directives.  */
  for (; level->kind != sk_namespace; level = level->level_chain)
    queue_usings (queue, SCOPE_DEPTH (scope), level->using_directives);

  for (; !found; scope = CP_DECL_CONTEXT (scope))
    {
      gcc_assert (!DECL_NAMESPACE_ALIAS (scope));
      int depth = SCOPE_DEPTH (scope);

      /* Queue namespaces reachable from SCOPE. */
      queue_namespace (queue, depth, scope);

      /* Search every queued namespace where SCOPE is the common
	 ancestor.  Adjust the others.  */
      unsigned ix = 0;
      do
	{
	  using_pair &pair = queue[ix];
	  while (pair.first == scope)
	    {
	      found |= search_namespace_only (pair.second);
	      pair = queue.pop ();
	      if (ix == queue.length ())
		goto done;
	    }
	  /* The depth is the same as SCOPE, find the parent scope.  */
	  if (SCOPE_DEPTH (pair.first) == depth)
	    pair.first = CP_DECL_CONTEXT (pair.first);
	  ix++;
	}
      while (ix < queue.length ());
    done:;
      if (scope == global_namespace)
	break;

      /* If looking for hidden friends, we only look in the innermost
	 namespace scope.  [namespace.memdef]/3 If a friend
	 declaration in a non-local class first declares a class,
	 function, class template or function template the friend is a
	 member of the innermost enclosing namespace.  See also
	 [basic.lookup.unqual]/7 */
      if (bool (want & LOOK_want::HIDDEN_FRIEND))
	break;
    }

  dedup (false);

  return found;
}

/* FNS is a value binding.  If it is a (set of overloaded) functions,
   add them into the current value.  */

void
name_lookup::add_fns (tree fns)
{
  if (!fns)
    return;
  else if (TREE_CODE (fns) == OVERLOAD)
    {
      if (TREE_TYPE (fns) != unknown_type_node)
	fns = OVL_FUNCTION (fns);
    }
  else if (!DECL_DECLARES_FUNCTION_P (fns))
    return;

  add_overload (fns);
}

/* Add the overloaded fns of SCOPE.  */

void
name_lookup::adl_namespace_fns (tree scope, bitmap imports)
{
  if (tree *binding = find_namespace_slot (scope, name))
    {
      tree val = *binding;
      if (TREE_CODE (val) != BINDING_VECTOR)
	add_fns (ovl_skip_hidden (MAYBE_STAT_DECL (val)));
      else
	{
	  /* I presume the binding list is going to be sparser than
	     the import bitmap.  Hence iterate over the former
	     checking for bits set in the bitmap.  */
	  binding_cluster *cluster = BINDING_VECTOR_CLUSTER_BASE (val);
	  int dup_detect = 0;

	  if (tree bind = cluster->slots[BINDING_SLOT_CURRENT])
	    {
	      /* The current TU's bindings must be visible, we don't
		 need to check the bitmaps.  */

	      if (!deduping)
		{
		  if (named_module_purview_p ())
		    {
		      dup_detect |= 2;

		      if (STAT_HACK_P (bind) && MODULE_BINDING_GLOBAL_P (bind))
			dup_detect |= 1;
		    }
		  else
		    dup_detect |= 1;
		}

	      add_fns (ovl_skip_hidden (MAYBE_STAT_DECL (bind)));
	    }

	  /* Scan the imported bindings.  */
	  unsigned ix = BINDING_VECTOR_NUM_CLUSTERS (val);
	  if (BINDING_VECTOR_SLOTS_PER_CLUSTER == BINDING_SLOTS_FIXED)
	    {
	      ix--;
	      cluster++;
	    }

	  /* Do this in forward order, so we load modules in an order
	     the user expects.  */
	  for (; ix--; cluster++)
	    for (unsigned jx = 0; jx != BINDING_VECTOR_SLOTS_PER_CLUSTER; jx++)
	      {
		/* Functions are never on merged slots.  */
		if (!cluster->indices[jx].base
		    || cluster->indices[jx].span != 1)
		  continue;

		/* Is this slot visible?  */
		if (!bitmap_bit_p (imports, cluster->indices[jx].base))
		  continue;

		/* Is it loaded.  */
		if (cluster->slots[jx].is_lazy ())
		  lazy_load_binding (cluster->indices[jx].base,
				     scope, name, &cluster->slots[jx]);

		tree bind = cluster->slots[jx];
		if (!bind)
		  /* Load errors could mean there's nothing here.  */
		  continue;

		if (STAT_HACK_P (bind))
		  {
		    if (!deduping)
		      {
			/* Do we need to engage deduplication?  */
			int dup = 0;
			if (MODULE_BINDING_GLOBAL_P (bind))
			  dup = 1;
			else if (MODULE_BINDING_PARTITION_P (bind))
			  dup = 2;
			if (unsigned hit = dup_detect & dup)
			  if ((hit & 1 && BINDING_VECTOR_GLOBAL_DUPS_P (val))
			      || (hit & 2
				  && BINDING_VECTOR_PARTITION_DUPS_P (val)))
			    dedup (true);
			dup_detect |= dup;
		      }

		    bind = STAT_VISIBLE (bind);
		  }

		add_fns (bind);
	      }
	}
    }
}

/* Add the hidden friends of SCOPE.  */

void
name_lookup::adl_class_fns (tree type)
{
  /* Add friends.  */
  for (tree list = DECL_FRIENDLIST (TYPE_MAIN_DECL (type));
       list; list = TREE_CHAIN (list))
    if (name == FRIEND_NAME (list))
      {
	tree context = NULL_TREE; /* Lazily computed.  */
	for (tree friends = FRIEND_DECLS (list); friends;
	     friends = TREE_CHAIN (friends))
	  {
	    tree fn = TREE_VALUE (friends);

	    /* Only interested in global functions with potentially hidden
	       (i.e. unqualified) declarations.  */
	    if (!context)
	      context = decl_namespace_context (type);
	    if (CP_DECL_CONTEXT (fn) != context)
	      continue;

	    dedup (true);

	    /* Template specializations are never found by name lookup.
	       (Templates themselves can be found, but not template
	       specializations.)  */
	    if (TREE_CODE (fn) == FUNCTION_DECL && DECL_USE_TEMPLATE (fn))
	      continue;

	    add_fns (fn);
	  }
      }
}

/* Find the containing non-inlined namespace, add it and all its
   inlinees.  */

void
name_lookup::adl_namespace (tree scope)
{
  if (see_and_mark (scope))
    return;

  /* Look down into inline namespaces.  */
  if (vec<tree, va_gc> *inlinees = DECL_NAMESPACE_INLINEES (scope))
    for (unsigned ix = inlinees->length (); ix--;)
      adl_namespace ((*inlinees)[ix]);

  if (DECL_NAMESPACE_INLINE_P (scope))
    /* Mark parent.  */
    adl_namespace (CP_DECL_CONTEXT (scope));
}

/* Adds the class and its friends to the lookup structure.  */

void
name_lookup::adl_class_only (tree type)
{
  /* Backend-built structures, such as __builtin_va_list, aren't
     affected by all this.  */
  if (!CLASS_TYPE_P (type))
    return;

  type = TYPE_MAIN_VARIANT (type);

  if (see_and_mark (type))
    return;

  tree context = decl_namespace_context (type);
  adl_namespace (context);
}

/* Adds the class and its bases to the lookup structure.
   Returns true on error.  */

void
name_lookup::adl_bases (tree type)
{
  adl_class_only (type);

  /* Process baseclasses.  */
  if (tree binfo = TYPE_BINFO (type))
    {
      tree base_binfo;
      int i;

      for (i = 0; BINFO_BASE_ITERATE (binfo, i, base_binfo); i++)
	adl_bases (BINFO_TYPE (base_binfo));
    }
}

/* Adds everything associated with a class argument type to the lookup
   structure.

   If T is a class type (including unions), its associated classes are: the
   class itself; the class of which it is a member, if any; and its direct
   and indirect base classes. Its associated namespaces are the namespaces
   of which its associated classes are members. Furthermore, if T is a
   class template specialization, its associated namespaces and classes
   also include: the namespaces and classes associated with the types of
   the template arguments provided for template type parameters (excluding
   template template parameters); the namespaces of which any template
   template arguments are members; and the classes of which any member
   templates used as template template arguments are members. [ Note:
   non-type template arguments do not contribute to the set of associated
   namespaces.  --end note] */

void
name_lookup::adl_class (tree type)
{
  /* Backend build structures, such as __builtin_va_list, aren't
     affected by all this.  */
  if (!CLASS_TYPE_P (type))
    return;

  type = TYPE_MAIN_VARIANT (type);

  /* We don't set found here because we have to have set seen first,
     which is done in the adl_bases walk.  */
  if (found_p (type))
    return;

  complete_type (type);
  adl_bases (type);
  mark_found (type);

  if (TYPE_CLASS_SCOPE_P (type))
    adl_class_only (TYPE_CONTEXT (type));

  /* Process template arguments.  */
  if (CLASSTYPE_TEMPLATE_INFO (type)
      && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (type)))
    {
      tree list = INNERMOST_TEMPLATE_ARGS (CLASSTYPE_TI_ARGS (type));
      for (int i = 0; i < TREE_VEC_LENGTH (list); ++i)
	adl_template_arg (TREE_VEC_ELT (list, i));
    }
}

void
name_lookup::adl_enum (tree type)
{
  type = TYPE_MAIN_VARIANT (type);
  if (see_and_mark (type))
    return;

  if (TYPE_CLASS_SCOPE_P (type))
    adl_class_only (TYPE_CONTEXT (type));
  else
    adl_namespace (decl_namespace_context (type));
}

void
name_lookup::adl_expr (tree expr)
{
  if (!expr)
    return;

  gcc_assert (!TYPE_P (expr));

  if (TREE_TYPE (expr) != unknown_type_node)
    {
      adl_type (unlowered_expr_type (expr));
      return;
    }

  if (TREE_CODE (expr) == ADDR_EXPR)
    expr = TREE_OPERAND (expr, 0);
  if (TREE_CODE (expr) == COMPONENT_REF
      || TREE_CODE (expr) == OFFSET_REF)
    expr = TREE_OPERAND (expr, 1);
  expr = MAYBE_BASELINK_FUNCTIONS (expr);

  if (OVL_P (expr))
    for (lkp_iterator iter (expr); iter; ++iter)
      adl_type (TREE_TYPE (*iter));
  else if (TREE_CODE (expr) == TEMPLATE_ID_EXPR)
    {
      /* The working paper doesn't currently say how to handle
	 template-id arguments.  The sensible thing would seem to be
	 to handle the list of template candidates like a normal
	 overload set, and handle the template arguments like we do
	 for class template specializations.  */

      /* First the templates.  */
      adl_expr (TREE_OPERAND (expr, 0));

      /* Now the arguments.  */
      if (tree args = TREE_OPERAND (expr, 1))
	for (int ix = TREE_VEC_LENGTH (args); ix--;)
	  adl_template_arg (TREE_VEC_ELT (args, ix));
    }
}

void
name_lookup::adl_type (tree type)
{
  if (!type)
    return;

  if (TYPE_PTRDATAMEM_P (type))
    {
      /* Pointer to member: associate class type and value type.  */
      adl_type (TYPE_PTRMEM_CLASS_TYPE (type));
      adl_type (TYPE_PTRMEM_POINTED_TO_TYPE (type));
      return;
    }

  switch (TREE_CODE (type))
    {
    case RECORD_TYPE:
      if (TYPE_PTRMEMFUNC_P (type))
	{
	  adl_type (TYPE_PTRMEMFUNC_FN_TYPE (type));
	  return;
	}
      /* FALLTHRU */
    case UNION_TYPE:
      adl_class (type);
      return;

    case METHOD_TYPE:
      /* The basetype is referenced in the first arg type, so just
	 fall through.  */
    case FUNCTION_TYPE:
      /* Associate the parameter types.  */
      for (tree args = TYPE_ARG_TYPES (type); args; args = TREE_CHAIN (args))
	adl_type (TREE_VALUE (args));
      /* FALLTHROUGH */

    case POINTER_TYPE:
    case REFERENCE_TYPE:
    case ARRAY_TYPE:
      adl_type (TREE_TYPE (type));
      return;

    case ENUMERAL_TYPE:
      adl_enum (type);
      return;

    case LANG_TYPE:
      gcc_assert (type == unknown_type_node
		  || type == init_list_type_node);
      return;

    case TYPE_PACK_EXPANSION:
      adl_type (PACK_EXPANSION_PATTERN (type));
      return;

    default:
      break;
    }
}

/* Adds everything associated with a template argument to the lookup
   structure.  */

void
name_lookup::adl_template_arg (tree arg)
{
  /* [basic.lookup.koenig]

     If T is a template-id, its associated namespaces and classes are
     ... the namespaces and classes associated with the types of the
     template arguments provided for template type parameters
     (excluding template template parameters); the namespaces in which
     any template template arguments are defined; and the classes in
     which any member templates used as template template arguments
     are defined.  [Note: non-type template arguments do not
     contribute to the set of associated namespaces.  ]  */

  /* Consider first template template arguments.  */
  if (TREE_CODE (arg) == TEMPLATE_TEMPLATE_PARM
      || TREE_CODE (arg) == UNBOUND_CLASS_TEMPLATE)
    ;
  else if (TREE_CODE (arg) == TEMPLATE_DECL)
    {
      tree ctx = CP_DECL_CONTEXT (arg);

      /* It's not a member template.  */
      if (TREE_CODE (ctx) == NAMESPACE_DECL)
	adl_namespace (ctx);
      /* Otherwise, it must be member template.  */
      else
	adl_class_only (ctx);
    }
  /* It's an argument pack; handle it recursively.  */
  else if (ARGUMENT_PACK_P (arg))
    {
      tree args = ARGUMENT_PACK_ARGS (arg);
      int i, len = TREE_VEC_LENGTH (args);
      for (i = 0; i < len; ++i) 
	adl_template_arg (TREE_VEC_ELT (args, i));
    }
  /* It's not a template template argument, but it is a type template
     argument.  */
  else if (TYPE_P (arg))
    adl_type (arg);
}

/* Perform ADL lookup.  FNS is the existing lookup result and ARGS are
   the call arguments.  */

tree
name_lookup::search_adl (tree fns, vec<tree, va_gc> *args)
{
  gcc_checking_assert (!vec_safe_length (scopes));
  
  /* Gather each associated entity onto the lookup's scope list.  */
  unsigned ix;
  tree arg;

  FOR_EACH_VEC_ELT_REVERSE (*args, ix, arg)
    /* OMP reduction operators put an ADL-significant type as the
       first arg. */
    if (TYPE_P (arg))
      adl_type (arg);
    else
      adl_expr (arg);

  if (vec_safe_length (scopes))
    {
      /* Now do the lookups.  */
      value = fns;
      if (fns)
	dedup (true);

      /* INST_PATH will be NULL, if this is /not/ 2nd-phase ADL.  */
      bitmap inst_path = NULL;
      /* VISIBLE is the regular import bitmap.  */
      bitmap visible = visible_instantiation_path (&inst_path);

      for (unsigned ix = scopes->length (); ix--;)
	{
	  tree scope = (*scopes)[ix];
	  if (TREE_CODE (scope) == NAMESPACE_DECL)
	    adl_namespace_fns (scope, visible);
	  else
	    {
	      if (RECORD_OR_UNION_TYPE_P (scope))
		adl_class_fns (scope);

	      /* During 2nd phase ADL: Any exported declaration D in N
		 declared within the purview of a named module M
		 (10.2) is visible if there is an associated entity
		 attached to M with the same innermost enclosing
		 non-inline namespace as D.
		 [basic.lookup.argdep]/4.4 */ 

	      if (!inst_path)
		/* Not 2nd phase.  */
		continue;

	      tree ctx = CP_DECL_CONTEXT (TYPE_NAME (scope));
	      if (TREE_CODE (ctx) != NAMESPACE_DECL)
		/* Not namespace-scope class.  */
		continue;

	      tree origin = get_originating_module_decl (TYPE_NAME (scope));
	      tree not_tmpl = STRIP_TEMPLATE (origin);
	      if (!DECL_LANG_SPECIFIC (not_tmpl)
		  || !DECL_MODULE_IMPORT_P (not_tmpl))
		/* Not imported.  */
		continue;

	      unsigned module = get_importing_module (origin);

	      if (!bitmap_bit_p (inst_path, module))
		/* Not on path of instantiation.  */
		continue;

	      if (bitmap_bit_p (visible, module))
		/* If the module was in the visible set, we'll look at
		   its namespace partition anyway.  */
		continue;

	      if (tree *slot = find_namespace_slot (ctx, name, false))
		if (binding_slot *mslot = search_imported_binding_slot (slot, module))
		  {
		    if (mslot->is_lazy ())
		      lazy_load_binding (module, ctx, name, mslot);

		    if (tree bind = *mslot)
		      {
			/* We must turn on deduping, because some other class
			   from this module might also be in this namespace.  */
			dedup (true);

			/* Add the exported fns  */
			if (STAT_HACK_P (bind))
			  add_fns (STAT_VISIBLE (bind));
		      }
		  }
	    }
	}

      fns = value;
      dedup (false);
    }

  return fns;
}

static bool qualified_namespace_lookup (tree, name_lookup *);
static void consider_binding_level (tree name,
				    best_match <tree, const char *> &bm,
				    cp_binding_level *lvl,
				    bool look_within_fields,
				    enum lookup_name_fuzzy_kind kind);

/* ADL lookup of NAME.  FNS is the result of regular lookup, and we
   don't add duplicates to it.  ARGS is the vector of call
   arguments (which will not be empty).  */

tree
lookup_arg_dependent (tree name, tree fns, vec<tree, va_gc> *args)
{
  auto_cond_timevar tv (TV_NAME_LOOKUP);
  name_lookup lookup (name);
  return lookup.search_adl (fns, args);
}

/* FNS is an overload set of conversion functions.  Return the
   overloads converting to TYPE.  */

static tree
extract_conversion_operator (tree fns, tree type)
{
  tree convs = NULL_TREE;
  tree tpls = NULL_TREE;

  for (ovl_iterator iter (fns); iter; ++iter)
    {
      if (same_type_p (DECL_CONV_FN_TYPE (*iter), type))
	convs = lookup_add (*iter, convs);

      if (TREE_CODE (*iter) == TEMPLATE_DECL)
	tpls = lookup_add (*iter, tpls);
    }

  if (!convs)
    convs = tpls;

  return convs;
}

/* Binary search of (ordered) MEMBER_VEC for NAME.  */

static tree
member_vec_binary_search (vec<tree, va_gc> *member_vec, tree name)
{
  for (unsigned lo = 0, hi = member_vec->length (); lo < hi;)
    {
      unsigned mid = (lo + hi) / 2;
      tree binding = (*member_vec)[mid];
      tree binding_name = OVL_NAME (binding);

      if (binding_name > name)
	hi = mid;
      else if (binding_name < name)
	lo = mid + 1;
      else
	return binding;
    }

  return NULL_TREE;
}

/* Linear search of (unordered) MEMBER_VEC for NAME.  */

static tree
member_vec_linear_search (vec<tree, va_gc> *member_vec, tree name)
{
  for (int ix = member_vec->length (); ix--;)
    if (tree binding = (*member_vec)[ix])
      if (OVL_NAME (binding) == name)
	return binding;

  return NULL_TREE;
}

/* Linear search of (partially ordered) fields of KLASS for NAME.  */

static tree
fields_linear_search (tree klass, tree name, bool want_type)
{
  for (tree fields = TYPE_FIELDS (klass); fields; fields = DECL_CHAIN (fields))
    {
      tree decl = fields;

      if (TREE_CODE (decl) == FIELD_DECL
	  && ANON_AGGR_TYPE_P (TREE_TYPE (decl)))
	{
	  if (tree temp = search_anon_aggr (TREE_TYPE (decl), name, want_type))
	    return temp;
	}

      if (DECL_NAME (decl) != name)
	continue;
      
      if (TREE_CODE (decl) == USING_DECL)
	{
	  decl = strip_using_decl (decl);
	  if (is_overloaded_fn (decl))
	    continue;
	}

      if (DECL_DECLARES_FUNCTION_P (decl))
	/* Functions are found separately.  */
	continue;

      if (!want_type || DECL_DECLARES_TYPE_P (decl))
	return decl;
    }

  return NULL_TREE;
}

/* Look for NAME member inside of anonymous aggregate ANON.  Although
   such things should only contain FIELD_DECLs, we check that too
   late, and would give very confusing errors if we weren't
   permissive here.  */

tree
search_anon_aggr (tree anon, tree name, bool want_type)
{
  gcc_assert (COMPLETE_TYPE_P (anon));
  tree ret = get_class_binding_direct (anon, name, want_type);
  return ret;
}

/* Look for NAME as an immediate member of KLASS (including
   anon-members or unscoped enum member).  TYPE_OR_FNS is zero for
   regular search.  >0 to get a type binding (if there is one) and <0
   if you want (just) the member function binding.

   Use this if you do not want lazy member creation.  */

tree
get_class_binding_direct (tree klass, tree name, bool want_type)
{
  gcc_checking_assert (RECORD_OR_UNION_TYPE_P (klass));

  /* Conversion operators can only be found by the marker conversion
     operator name.  */
  bool conv_op = IDENTIFIER_CONV_OP_P (name);
  tree lookup = conv_op ? conv_op_identifier : name;
  tree val = NULL_TREE;
  vec<tree, va_gc> *member_vec = CLASSTYPE_MEMBER_VEC (klass);

  if (COMPLETE_TYPE_P (klass) && member_vec)
    {
      val = member_vec_binary_search (member_vec, lookup);
      if (!val)
	;
      else if (STAT_HACK_P (val))
	val = want_type ? STAT_TYPE (val) : STAT_DECL (val);
      else if (want_type && !DECL_DECLARES_TYPE_P (val))
	val = NULL_TREE;
    }
  else
    {
      if (member_vec && !want_type)
	val = member_vec_linear_search (member_vec, lookup);

      if (!val || (TREE_CODE (val) == OVERLOAD && OVL_DEDUP_P (val)))
	/* Dependent using declarations are a 'field', make sure we
	   return that even if we saw an overload already.  */
	if (tree field_val = fields_linear_search (klass, lookup, want_type))
	  {
	    if (!val)
	      val = field_val;
	    else if (TREE_CODE (field_val) == USING_DECL)
	      val = ovl_make (field_val, val);
	  }
    }

  /* Extract the conversion operators asked for, unless the general
     conversion operator was requested.   */
  if (val && conv_op)
    {
      gcc_checking_assert (OVL_FUNCTION (val) == conv_op_marker);
      val = OVL_CHAIN (val);
      if (tree type = TREE_TYPE (name))
	val = extract_conversion_operator (val, type);
    }

  return val;
}

/* We're about to lookup NAME in KLASS.  Make sure any lazily declared
   members are now declared.  */

static void
maybe_lazily_declare (tree klass, tree name)
{
  /* See big comment anout module_state::write_pendings regarding adding a check
     bit.  */
  if (modules_p ())
    lazy_load_pendings (TYPE_NAME (klass));

  /* Lazily declare functions, if we're going to search these.  */
  if (IDENTIFIER_CTOR_P (name))
    {
      if (CLASSTYPE_LAZY_DEFAULT_CTOR (klass))
	lazily_declare_fn (sfk_constructor, klass);
      if (CLASSTYPE_LAZY_COPY_CTOR (klass))
	lazily_declare_fn (sfk_copy_constructor, klass);
      if (CLASSTYPE_LAZY_MOVE_CTOR (klass))
	lazily_declare_fn (sfk_move_constructor, klass);
    }
  else if (IDENTIFIER_DTOR_P (name))
    {
      if (CLASSTYPE_LAZY_DESTRUCTOR (klass))
	lazily_declare_fn (sfk_destructor, klass);
    }
  else if (name == assign_op_identifier)
    {
      if (CLASSTYPE_LAZY_COPY_ASSIGN (klass))
	lazily_declare_fn (sfk_copy_assignment, klass);
      if (CLASSTYPE_LAZY_MOVE_ASSIGN (klass))
	lazily_declare_fn (sfk_move_assignment, klass);
    }
}

/* Look for NAME's binding in exactly KLASS.  See
   get_class_binding_direct for argument description.  Does lazy
   special function creation as necessary.  */

tree
get_class_binding (tree klass, tree name, bool want_type /*=false*/)
{
  klass = complete_type (klass);

  if (COMPLETE_TYPE_P (klass))
    maybe_lazily_declare (klass, name);

  return get_class_binding_direct (klass, name, want_type);
}

/* Find the slot containing overloads called 'NAME'.  If there is no
   such slot and the class is complete, create an empty one, at the
   correct point in the sorted member vector.  Otherwise return NULL.
   Deals with conv_op marker handling.  */

tree *
find_member_slot (tree klass, tree name)
{
  bool complete_p = COMPLETE_TYPE_P (klass);

  vec<tree, va_gc> *member_vec = CLASSTYPE_MEMBER_VEC (klass);
  if (!member_vec)
    {
      vec_alloc (member_vec, 8);
      CLASSTYPE_MEMBER_VEC (klass) = member_vec;
      if (complete_p)
	/* If the class is complete but had no member_vec, we need to
	   add the TYPE_FIELDS into it.  We're also most likely to be
	   adding ctors & dtors, so ask for 6 spare slots (the
	   abstract cdtors and their clones).  */
	member_vec = set_class_bindings (klass, 6);
    }

  if (IDENTIFIER_CONV_OP_P (name))
    name = conv_op_identifier;

  unsigned ix, length = member_vec->length ();
  for (ix = 0; ix < length; ix++)
    {
      tree *slot = &(*member_vec)[ix];
      tree fn_name = OVL_NAME (*slot);

      if (fn_name == name)
	{
	  /* If we found an existing slot, it must be a function set.
	     Even with insertion after completion, because those only
	     happen with artificial fns that have unspellable names.
	     This means we do not have to deal with the stat hack
	     either.  */
	  gcc_checking_assert (OVL_P (*slot));
	  if (name == conv_op_identifier)
	    {
	      gcc_checking_assert (OVL_FUNCTION (*slot) == conv_op_marker);
	      /* Skip the conv-op marker. */
	      slot = &OVL_CHAIN (*slot);
	    }
	  return slot;
	}

      if (complete_p && fn_name > name)
	break;
    }

  /* No slot found, add one if the class is complete.  */
  if (complete_p)
    {
      /* Do exact allocation, as we don't expect to add many.  */
      gcc_assert (name != conv_op_identifier);
      vec_safe_reserve_exact (member_vec, 1);
      CLASSTYPE_MEMBER_VEC (klass) = member_vec;
      member_vec->quick_insert (ix, NULL_TREE);
      return &(*member_vec)[ix];
    }

  return NULL;
}

/* KLASS is an incomplete class to which we're adding a method NAME.
   Add a slot and deal with conv_op marker handling.  */

tree *
add_member_slot (tree klass, tree name)
{
  gcc_assert (!COMPLETE_TYPE_P (klass));

  vec<tree, va_gc> *member_vec = CLASSTYPE_MEMBER_VEC (klass);
  vec_safe_push (member_vec, NULL_TREE);
  CLASSTYPE_MEMBER_VEC (klass) = member_vec;

  tree *slot = &member_vec->last ();
  if (IDENTIFIER_CONV_OP_P (name))
    {
      /* Install the marker prefix.  */
      *slot = ovl_make (conv_op_marker, NULL_TREE);
      slot = &OVL_CHAIN (*slot);
    }

  return slot;
}

/* Comparison function to compare two MEMBER_VEC entries by name.
   Because we can have duplicates during insertion of TYPE_FIELDS, we
   do extra checking so deduping doesn't have to deal with so many
   cases.  */

static int
member_name_cmp (const void *a_p, const void *b_p)
{
  tree a = *(const tree *)a_p;
  tree b = *(const tree *)b_p;
  tree name_a = DECL_NAME (TREE_CODE (a) == OVERLOAD ? OVL_FUNCTION (a) : a);
  tree name_b = DECL_NAME (TREE_CODE (b) == OVERLOAD ? OVL_FUNCTION (b) : b);

  gcc_checking_assert (name_a && name_b);
  if (name_a != name_b)
    return name_a < name_b ? -1 : +1;

  if (name_a == conv_op_identifier)
    {
      /* Strip the conv-op markers. */
      gcc_checking_assert (OVL_FUNCTION (a) == conv_op_marker
			   && OVL_FUNCTION (b) == conv_op_marker);
      a = OVL_CHAIN (a);
      b = OVL_CHAIN (b);
    }

  if (TREE_CODE (a) == OVERLOAD)
    a = OVL_FUNCTION (a);
  if (TREE_CODE (b) == OVERLOAD)
    b = OVL_FUNCTION (b);

  /* We're in STAT_HACK or USING_DECL territory (or possibly error-land). */
  if (TREE_CODE (a) != TREE_CODE (b))
    {
      /* If one of them is a TYPE_DECL, it loses.  */
      if (TREE_CODE (a) == TYPE_DECL)
	return +1;
      else if (TREE_CODE (b) == TYPE_DECL)
	return -1;

      /* If one of them is a USING_DECL, it loses.  */
      if (TREE_CODE (a) == USING_DECL)
	return +1;
      else if (TREE_CODE (b) == USING_DECL)
	return -1;

      /* There are no other cases with different kinds of decls, as
	 duplicate detection should have kicked in earlier.  However,
	 some erroneous cases get though. */
      gcc_assert (errorcount);
    }
  
  /* Using source location would be the best thing here, but we can
     get identically-located decls in the following circumstances:

     1) duplicate artificial type-decls for the same type.

     2) pack expansions of using-decls.

     We should not be doing #1, but in either case it doesn't matter
     how we order these.  Use UID as a proxy for source ordering, so
     that identically-located decls still have a well-defined stable
     ordering.  */
  if (DECL_UID (a) != DECL_UID (b))
    return DECL_UID (a) < DECL_UID (b) ? -1 : +1;
  gcc_assert (a == b);
  return 0;
}

static struct {
  gt_pointer_operator new_value;
  void *cookie;
} resort_data;

/* This routine compares two fields like member_name_cmp but using the
   pointer operator in resort_field_decl_data.  We don't have to deal
   with duplicates here.  */

static int
resort_member_name_cmp (const void *a_p, const void *b_p)
{
  tree a = *(const tree *)a_p;
  tree b = *(const tree *)b_p;
  tree name_a = OVL_NAME (a);
  tree name_b = OVL_NAME (b);

  resort_data.new_value (&name_a, &name_a, resort_data.cookie);
  resort_data.new_value (&name_b, &name_b, resort_data.cookie);

  gcc_checking_assert (name_a != name_b);

  return name_a < name_b ? -1 : +1;
}

/* Resort CLASSTYPE_MEMBER_VEC because pointers have been reordered.  */

void
resort_type_member_vec (void *obj, void */*orig_obj*/,
			gt_pointer_operator new_value, void* cookie)
{
  if (vec<tree, va_gc> *member_vec = (vec<tree, va_gc> *) obj)
    {
      resort_data.new_value = new_value;
      resort_data.cookie = cookie;
      member_vec->qsort (resort_member_name_cmp);
    }
}

/* Recursively count the number of fields in KLASS, including anonymous
   union members.  */

static unsigned
count_class_fields (tree klass)
{
  unsigned n_fields = 0;

  for (tree fields = TYPE_FIELDS (klass); fields; fields = DECL_CHAIN (fields))
    if (DECL_DECLARES_FUNCTION_P (fields))
      /* Functions are dealt with separately.  */;
    else if (TREE_CODE (fields) == FIELD_DECL
	     && ANON_AGGR_TYPE_P (TREE_TYPE (fields)))
      n_fields += count_class_fields (TREE_TYPE (fields));
    else if (DECL_NAME (fields))
      n_fields += 1;

  return n_fields;
}

/* Append all the nonfunction members fields of KLASS to MEMBER_VEC.
   Recurse for anonymous members.  MEMBER_VEC must have space.  */

static void
member_vec_append_class_fields (vec<tree, va_gc> *member_vec, tree klass)
{
  for (tree fields = TYPE_FIELDS (klass); fields; fields = DECL_CHAIN (fields))
    if (DECL_DECLARES_FUNCTION_P (fields))
      /* Functions are handled separately.  */;
    else if (TREE_CODE (fields) == FIELD_DECL
	     && ANON_AGGR_TYPE_P (TREE_TYPE (fields)))
      member_vec_append_class_fields (member_vec, TREE_TYPE (fields));
    else if (DECL_NAME (fields))
      {
	tree field = fields;
	/* Mark a conv-op USING_DECL with the conv-op-marker.  */
	if (TREE_CODE (field) == USING_DECL
	    && IDENTIFIER_CONV_OP_P (DECL_NAME (field)))
	  field = ovl_make (conv_op_marker, field);
	member_vec->quick_push (field);
      }
}

/* Append all of the enum values of ENUMTYPE to MEMBER_VEC.
   MEMBER_VEC must have space.  */

static void
member_vec_append_enum_values (vec<tree, va_gc> *member_vec, tree enumtype)
{
  for (tree values = TYPE_VALUES (enumtype);
       values; values = TREE_CHAIN (values))
    member_vec->quick_push (TREE_VALUE (values));
}

/* MEMBER_VEC has just had new DECLs added to it, but is sorted.
   DeDup adjacent DECLS of the same name.  We already dealt with
   conflict resolution when adding the fields or methods themselves.
   There are three cases (which could all be combined):
   1) a TYPE_DECL and non TYPE_DECL.  Deploy STAT_HACK as appropriate.
   2) a USING_DECL and an overload.  If the USING_DECL is dependent,
   it wins.  Otherwise the OVERLOAD does.
   3) two USING_DECLS. ...

   member_name_cmp will have ordered duplicates as
   <fns><using><type>  */

static void
member_vec_dedup (vec<tree, va_gc> *member_vec)
{
  unsigned len = member_vec->length ();
  unsigned store = 0;

  if (!len)
    return;

  tree name = OVL_NAME ((*member_vec)[0]);
  for (unsigned jx, ix = 0; ix < len; ix = jx)
    {
      tree current = NULL_TREE;
      tree to_type = NULL_TREE;
      tree to_using = NULL_TREE;
      tree marker = NULL_TREE;

      for (jx = ix; jx < len; jx++)
	{
	  tree next = (*member_vec)[jx];
	  if (jx != ix)
	    {
	      tree next_name = OVL_NAME (next);
	      if (next_name != name)
		{
		  name = next_name;
		  break;
		}
	    }

	  if (IDENTIFIER_CONV_OP_P (name))
	    {
	      marker = next;
	      next = OVL_CHAIN (next);
	    }

	  if (TREE_CODE (next) == USING_DECL)
	    {
	      if (IDENTIFIER_CTOR_P (name))
		/* Dependent inherited ctor. */
		continue;

	      next = strip_using_decl (next);
	      if (TREE_CODE (next) == USING_DECL)
		{
		  to_using = next;
		  continue;
		}

	      if (is_overloaded_fn (next))
		continue;
	    }

	  if (DECL_DECLARES_TYPE_P (next))
	    {
	      to_type = next;
	      continue;
	    }

	  if (!current)
	    current = next;
	}

      if (to_using)
	{
	  if (!current)
	    current = to_using;
	  else
	    current = ovl_make (to_using, current);
	}

      if (to_type)
	{
	  if (!current)
	    current = to_type;
	  else
	    current = stat_hack (current, to_type);
	}

      if (current)
	{
	  if (marker)
	    {
	      OVL_CHAIN (marker) = current;
	      current = marker;
	    }
	  (*member_vec)[store++] = current;
	}
    }

  while (store++ < len)
    member_vec->pop ();
}

/* Add the non-function members to CLASSTYPE_MEMBER_VEC.  If there is
   no existing MEMBER_VEC and fewer than 8 fields, do nothing.  We
   know there must be at least 1 field -- the self-reference
   TYPE_DECL, except for anon aggregates, which will have at least
   one field anyway.  If EXTRA < 0, always create the vector.  */

vec<tree, va_gc> *
set_class_bindings (tree klass, int extra)
{
  unsigned n_fields = count_class_fields (klass);
  vec<tree, va_gc> *member_vec = CLASSTYPE_MEMBER_VEC (klass);

  if (member_vec || n_fields >= 8 || extra < 0)
    {
      /* Append the new fields.  */
      vec_safe_reserve_exact (member_vec, n_fields + (extra >= 0 ? extra : 0));
      member_vec_append_class_fields (member_vec, klass);
    }

  if (member_vec)
    {
      CLASSTYPE_MEMBER_VEC (klass) = member_vec;
      member_vec->qsort (member_name_cmp);
      member_vec_dedup (member_vec);
    }

  return member_vec;
}

/* Insert lately defined enum ENUMTYPE into KLASS for the sorted case.  */

void
insert_late_enum_def_bindings (tree klass, tree enumtype)
{
  int n_fields;
  vec<tree, va_gc> *member_vec = CLASSTYPE_MEMBER_VEC (klass);

  /* The enum bindings will already be on the TYPE_FIELDS, so don't
     count them twice.  */
  if (!member_vec)
    n_fields = count_class_fields (klass);
  else
    n_fields = list_length (TYPE_VALUES (enumtype));

  if (member_vec || n_fields >= 8)
    {
      vec_safe_reserve_exact (member_vec, n_fields);
      if (CLASSTYPE_MEMBER_VEC (klass))
	member_vec_append_enum_values (member_vec, enumtype);
      else
	member_vec_append_class_fields (member_vec, klass);
      CLASSTYPE_MEMBER_VEC (klass) = member_vec;
      member_vec->qsort (member_name_cmp);
      member_vec_dedup (member_vec);
    }
}

/* The binding oracle; see cp-tree.h.  */

cp_binding_oracle_function *cp_binding_oracle;

/* If we have a binding oracle, ask it for all namespace-scoped
   definitions of NAME.  */

static inline void
query_oracle (tree name)
{
  if (!cp_binding_oracle)
    return;

  /* LOOKED_UP holds the set of identifiers that we have already
     looked up with the oracle.  */
  static hash_set<tree> looked_up;
  if (looked_up.add (name))
    return;

  cp_binding_oracle (CP_ORACLE_IDENTIFIER, name);
}

#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 = free_bindings;

  if (binding)
    free_bindings = binding->previous;
  else
    binding = ggc_alloc<cxx_binding> ();

  /* Clear flags by default.  */
  LOCAL_BINDING_P (binding) = false;
  INHERITED_VALUE_BINDING_P (binding) = false;
  HIDDEN_TYPE_BINDING_P (binding) = false;

  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_make (value, type), name};
  cxx_binding *binding = cb.base;
  vec_safe_push (scope->class_shadowed, cb);
  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.  */

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);
  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_local_binding (tree id, tree decl)
{
  if (!id || IDENTIFIER_ANON_P (id))
    /* 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.  */
  cxx_binding *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.  We don't have to
     clear HIDDEN_TYPE_BINDING_P, as the whole binding will be going
     away.  */
  if (binding->value == decl)
    binding->value = NULL_TREE;
  else
    {
      gcc_checking_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);
    }
}

/* Remove the bindings for the decls of the current level and leave
   the current scope.  */

void
pop_bindings_and_leave_scope (void)
{
  for (tree t = get_local_decls (); t; t = DECL_CHAIN (t))
    {
      tree decl = TREE_CODE (t) == TREE_LIST ? TREE_VALUE (t) : t;
      tree name = OVL_NAME (decl);

      pop_local_binding (name, decl);
    }

  leave_scope ();
}

/* Strip non dependent using declarations. If DECL is dependent,
   surreptitiously create a typename_type and return it.  */

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);

  if (TREE_CODE (decl) == USING_DECL && DECL_DEPENDENT_P (decl)
      && USING_DECL_TYPENAME_P (decl))
    {
      /* We have found a type introduced by a using
	 declaration at class scope that refers to a dependent
	 type.
	     
	 using typename :: [opt] nested-name-specifier unqualified-id ;
      */
      decl = make_typename_type (USING_DECL_SCOPE (decl),
				 DECL_NAME (decl),
				 typename_type, tf_error);
      if (decl != error_mark_node)
	decl = TYPE_NAME (decl);
    }

  return decl;
}

/* Return true if OVL is an overload for an anticipated builtin.  */

static bool
anticipated_builtin_p (tree ovl)
{
  return (TREE_CODE (ovl) == OVERLOAD
	  && OVL_HIDDEN_P (ovl)
	  && DECL_IS_UNDECLARED_BUILTIN (OVL_FUNCTION (ovl)));
}

/* 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 (cxx_binding *binding, tree decl)
{
  auto_cond_timevar tv (TV_NAME_LOOKUP);

  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.  */
	  || (processing_template_decl
	      && 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.  */
	   || anticipated_builtin_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 (VAR_P (target_decl)
	   && VAR_P (target_bval)
	   && DECL_EXTERNAL (target_decl) && DECL_EXTERNAL (target_bval)
	   && !DECL_CLASS_SCOPE_P (target_decl))
    {
      duplicate_decls (decl, binding->value);
      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 if (TREE_CODE (bval) == USING_DECL
	   && CONST_DECL_USING_P (decl))
    /* Let the clone hide the using-decl that introduced it.  */
    binding->value = decl;
  else
    {
      if (!error_operand_p (bval))
	diagnose_name_conflict (decl, bval);
      ok = false;
    }

  return ok;
}

/* Diagnose a name conflict between DECL and BVAL.

   This is non-static so maybe_push_used_methods can use it and avoid changing
   the diagnostic for inherit/using4.C; otherwise it should not be used from
   outside this file.  */

void
diagnose_name_conflict (tree decl, tree bval)
{
  if (TREE_CODE (decl) == TREE_CODE (bval)
      && TREE_CODE (decl) != NAMESPACE_DECL
      && !DECL_DECLARES_FUNCTION_P (decl)
      && (TREE_CODE (decl) != TYPE_DECL
	  || DECL_ARTIFICIAL (decl) == DECL_ARTIFICIAL (bval))
      && CP_DECL_CONTEXT (decl) == CP_DECL_CONTEXT (bval))
    {
      if (concept_definition_p (decl))
        error ("redeclaration of %q#D with different template parameters",
               decl);
      else
        error ("redeclaration of %q#D", decl);
    }
  else
    error ("%q#D conflicts with a previous declaration", decl);

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

/* Replace BINDING's current value on its scope's name list with
   NEWVAL.  */

static void
update_local_overload (cxx_binding *binding, tree newval)
{
  tree *d;

  for (d = &binding->scope->names; ; d = &TREE_CHAIN (*d))
    if (*d == binding->value)
      {
	/* Stitch new list node in.  */
	*d = tree_cons (DECL_NAME (*d), NULL_TREE, TREE_CHAIN (*d));
	break;
      }
    else if (TREE_CODE (*d) == TREE_LIST && TREE_VALUE (*d) == binding->value)
      break;

  TREE_VALUE (*d) = newval;
}

/* Compares the parameter-type-lists of ONE and TWO and
   returns false if they are different.  If the DECLs are template
   functions, the return types and the template parameter lists are
   compared too (DR 565).  */

static bool
matching_fn_p (tree one, tree two)
{
  if (TREE_CODE (one) != TREE_CODE (two))
    return false;

  if (!compparms (TYPE_ARG_TYPES (TREE_TYPE (one)),
		  TYPE_ARG_TYPES (TREE_TYPE (two))))
    return false;

  if (TREE_CODE (one) == TEMPLATE_DECL)
    {
      /* Compare template parms.  */
      if (!comp_template_parms (DECL_TEMPLATE_PARMS (one),
				DECL_TEMPLATE_PARMS (two)))
	return false;

      /* And return type.  */
      if (!same_type_p (TREE_TYPE (TREE_TYPE (one)),
			TREE_TYPE (TREE_TYPE (two))))
	return false;
    }

  if (!equivalently_constrained (one, two))
    return false;

  return true;
}

/* Push DECL into nonclass LEVEL BINDING or SLOT.  OLD is the current
   binding value (possibly with anticipated builtins stripped).
   Diagnose conflicts and return updated decl.  */

static tree
update_binding (cp_binding_level *level, cxx_binding *binding, tree *slot,
		tree old, tree decl, bool hiding = false)
{
  tree old_type = NULL_TREE;
  bool hide_type = false;
  bool hide_value = false;

  if (!slot)
    {
      old_type = binding->type;
      hide_type = HIDDEN_TYPE_BINDING_P (binding);
      if (!old_type)
	hide_value = hide_type, hide_type = false;
    }
  else if (STAT_HACK_P (*slot))
    {
      old_type = STAT_TYPE (*slot);
      hide_type = STAT_TYPE_HIDDEN_P (*slot);
      hide_value = STAT_DECL_HIDDEN_P (*slot);
    }

  tree to_val = decl;
  tree to_type = old_type;
  bool local_overload = false;

  gcc_assert (!level || level->kind == sk_namespace ? !binding
	      : level->kind != sk_class && !slot);

  if (old == error_mark_node)
    old = NULL_TREE;

  if (DECL_IMPLICIT_TYPEDEF_P (decl))
    {
      /* Pushing an artificial decl.  We should not find another
         artificial decl here already -- lookup_elaborated_type will
         have already found it.  */
      gcc_checking_assert (!to_type
			   && !(old && DECL_IMPLICIT_TYPEDEF_P (old)));

      if (old)
	{
	  /* Put DECL into the type slot.  */
	  gcc_checking_assert (!to_type);
	  hide_type = hiding;
	  to_type = decl;
	  to_val = old;
	}
      else
	hide_value = hiding;

      goto done;
    }

  if (old && DECL_IMPLICIT_TYPEDEF_P (old))
    {
      /* OLD is an implicit typedef.  Move it to to_type.  */
      gcc_checking_assert (!to_type);

      to_type = old;
      hide_type = hide_value;
      old = NULL_TREE;
      hide_value = false;
    }

  if (DECL_DECLARES_FUNCTION_P (decl))
    {
      if (!old)
	;
      else if (OVL_P (old))
	{
	  for (ovl_iterator iter (old); iter; ++iter)
	    {
	      tree fn = *iter;

	      if (iter.using_p () && matching_fn_p (fn, decl))
		{
		  gcc_checking_assert (!iter.hidden_p ());
		  /* If a function declaration in namespace scope or
		     block scope has the same name and the same
		     parameter-type- list (8.3.5) as a function
		     introduced by a using-declaration, and the
		     declarations do not declare the same function,
		     the program is ill-formed.  [namespace.udecl]/14 */
		  if (tree match = duplicate_decls (decl, fn, hiding))
		    return match;
		  else
		    /* FIXME: To preserve existing error behavior, we
		       still push the decl.  This might change.  */
		    diagnose_name_conflict (decl, fn);
		}
	    }
	}
      else
	goto conflict;

      if (to_type != old_type
	  && warn_shadow
	  && MAYBE_CLASS_TYPE_P (TREE_TYPE (to_type))
	  && !(DECL_IN_SYSTEM_HEADER (decl)
	       && DECL_IN_SYSTEM_HEADER (to_type)))
	warning (OPT_Wshadow, "%q#D hides constructor for %q#D",
		 decl, to_type);

      local_overload = old && level && level->kind != sk_namespace;
      to_val = ovl_insert (decl, old, -int (hiding));
    }
  else if (old)
    {
      if (TREE_CODE (old) != TREE_CODE (decl))
	/* Different kinds of decls conflict.  */
	goto conflict;
      else if (TREE_CODE (old) == TYPE_DECL)
	{
	  if (same_type_p (TREE_TYPE (old), TREE_TYPE (decl)))
	    /* Two type decls to the same type.  Do nothing.  */
	    return old;
	  else
	    goto conflict;
	}
      else if (TREE_CODE (old) == NAMESPACE_DECL)
	{
	  /* Two maybe-aliased namespaces.  If they're to the same target
	     namespace, that's ok.  */
	  if (ORIGINAL_NAMESPACE (old) != ORIGINAL_NAMESPACE (decl))
	    goto conflict;

	  /* The new one must be an alias at this point.  */
	  gcc_assert (DECL_NAMESPACE_ALIAS (decl));
	  return old;
	}
      else if (TREE_CODE (old) == VAR_DECL)
	{
	  /* There can be two block-scope declarations of the same
	     variable, so long as they are `extern' declarations.  */
	  if (!DECL_EXTERNAL (old) || !DECL_EXTERNAL (decl))
	    goto conflict;
	  else if (tree match = duplicate_decls (decl, old))
	    {
	      gcc_checking_assert (!hide_value && !hiding);
	      return match;
	    }
	  else
	    goto conflict;
	}
      else
	{
	conflict:
	  diagnose_name_conflict (decl, old);
	  to_val = NULL_TREE;
	}
    }
  else if (hiding)
    hide_value = true;

 done:
  if (to_val)
    {
      if (local_overload)
	{
	  gcc_checking_assert (binding->value && OVL_P (binding->value));
	  update_local_overload (binding, to_val);
	}
      else if (level
	       && !(TREE_CODE (decl) == NAMESPACE_DECL
		    && !DECL_NAMESPACE_ALIAS (decl)))
	/* Don't add namespaces here.  They're done in
	   push_namespace.  */
	add_decl_to_level (level, decl);

      if (slot)
	{
	  if (STAT_HACK_P (*slot))
	    {
	      STAT_TYPE (*slot) = to_type;
	      STAT_DECL (*slot) = to_val;
	      STAT_TYPE_HIDDEN_P (*slot) = hide_type;
	      STAT_DECL_HIDDEN_P (*slot) = hide_value;
	    }
	  else if (to_type || hide_value)
	    {
	      *slot = stat_hack (to_val, to_type);
	      STAT_TYPE_HIDDEN_P (*slot) = hide_type;
	      STAT_DECL_HIDDEN_P (*slot) = hide_value;
	    }
	  else
	    {
	      gcc_checking_assert (!hide_type);
	      *slot = to_val;
	    }
	}
      else
	{
	  binding->type = to_type;
	  binding->value = to_val;
	  HIDDEN_TYPE_BINDING_P (binding) = hide_type || hide_value;
	}
    }

  return decl;
}

/* Table of identifiers to extern C declarations (or LISTS thereof).  */

static GTY(()) hash_table<named_decl_hash> *extern_c_decls;

/* DECL has C linkage. If we have an existing instance, make sure the
   new one is compatible.  Make sure it has the same exception
   specification [7.5, 7.6].  Add DECL to the map.  */

static void
check_extern_c_conflict (tree decl)
{
  /* Ignore artificial or system header decls.  */
  if (DECL_ARTIFICIAL (decl) || DECL_IN_SYSTEM_HEADER (decl))
    return;

  /* This only applies to decls at namespace scope.  */
  if (!DECL_NAMESPACE_SCOPE_P (decl))
    return;

  if (!extern_c_decls)
    extern_c_decls = hash_table<named_decl_hash>::create_ggc (127);

  tree *slot = extern_c_decls
    ->find_slot_with_hash (DECL_NAME (decl),
			   IDENTIFIER_HASH_VALUE (DECL_NAME (decl)), INSERT);
  if (tree old = *slot)
    {
      if (TREE_CODE (old) == OVERLOAD)
	old = OVL_FUNCTION (old);

      int mismatch = 0;
      if (DECL_CONTEXT (old) == DECL_CONTEXT (decl))
	; /* If they're in the same context, we'll have already complained
	     about a (possible) mismatch, when inserting the decl.  */
      else if (!decls_match (decl, old))
	mismatch = 1;
      else if (TREE_CODE (decl) == FUNCTION_DECL
	       && !comp_except_specs (TYPE_RAISES_EXCEPTIONS (TREE_TYPE (old)),
				      TYPE_RAISES_EXCEPTIONS (TREE_TYPE (decl)),
				      ce_normal))
	mismatch = -1;
      else if (DECL_ASSEMBLER_NAME_SET_P (old))
	SET_DECL_ASSEMBLER_NAME (decl, DECL_ASSEMBLER_NAME (old));

      if (mismatch)
	{
	  auto_diagnostic_group d;
	  pedwarn (DECL_SOURCE_LOCATION (decl), 0,
		   "conflicting C language linkage declaration %q#D", decl);
	  inform (DECL_SOURCE_LOCATION (old),
		  "previous declaration %q#D", old);
	  if (mismatch < 0)
	    inform (DECL_SOURCE_LOCATION (decl),
		    "due to different exception specifications");
	}
      else
	{
	  if (old == *slot)
	    /* The hash table expects OVERLOADS, so construct one with
	       OLD as both the function and the chain.  This allocate
	       an excess OVERLOAD node, but it's rare to have multiple
	       extern "C" decls of the same name.  And we save
	       complicating the hash table logic (which is used
	       elsewhere).  */
	    *slot = ovl_make (old, old);

	  slot = &OVL_CHAIN (*slot);

	  /* Chain it on for c_linkage_binding's use.  */
	  *slot = tree_cons (NULL_TREE, decl, *slot);
	}
    }
  else
    *slot = decl;
}

/* Returns a list of C-linkage decls with the name NAME.  Used in
   c-family/c-pragma.cc to implement redefine_extname pragma.  */

tree
c_linkage_bindings (tree name)
{
  if (extern_c_decls)
    if (tree *slot = extern_c_decls
	->find_slot_with_hash (name, IDENTIFIER_HASH_VALUE (name), NO_INSERT))
      {
	tree result = *slot;
	if (TREE_CODE (result) == OVERLOAD)
	  result = OVL_CHAIN (result);
	return result;
      }

  return NULL_TREE;
}

/* Subroutine of check_local_shadow.  */

static void
inform_shadowed (tree shadowed)
{
  inform (DECL_SOURCE_LOCATION (shadowed),
	  "shadowed declaration is here");
}

/* DECL is being declared at a local scope.  Emit suitable shadow
   warnings.  */

static void
check_local_shadow (tree decl)
{
  /* Don't complain about the parms we push and then pop
     while tentatively parsing a function declarator.  */
  if (TREE_CODE (decl) == PARM_DECL && !DECL_CONTEXT (decl))
    return;

  /* External decls are something else.  */
  if (DECL_EXTERNAL (decl))
    return;

  tree old = NULL_TREE;
  cp_binding_level *old_scope = NULL;
  if (cxx_binding *binding = outer_binding (DECL_NAME (decl), NULL, true))
    {
      old = binding->value;
      old_scope = binding->scope;
    }

  if (old
      && (TREE_CODE (old) == PARM_DECL
	  || VAR_P (old)
	  || (TREE_CODE (old) == TYPE_DECL
	      && (!DECL_ARTIFICIAL (old)
		  || TREE_CODE (decl) == TYPE_DECL)))
      && DECL_FUNCTION_SCOPE_P (old)
      && (!DECL_ARTIFICIAL (decl)
	  || is_capture_proxy (decl)
	  || DECL_IMPLICIT_TYPEDEF_P (decl)
	  || (VAR_P (decl) && DECL_ANON_UNION_VAR_P (decl))))
    {
      /* DECL shadows a local thing possibly of interest.  */

      /* DR 2211: check that captures and parameters
	 do not have the same name. */
      if (is_capture_proxy (decl))
	{
	  if (current_lambda_expr ()
	      && DECL_CONTEXT (old) == lambda_function (current_lambda_expr ())
	      && TREE_CODE (old) == PARM_DECL
	      && DECL_NAME (decl) != this_identifier)
	    {
	      error_at (DECL_SOURCE_LOCATION (old),
			"lambda parameter %qD "
			"previously declared as a capture", old);
	    }
	  return;
	}
      /* Don't complain if it's from an enclosing function.  */
      else if (DECL_CONTEXT (old) == current_function_decl
	       && TREE_CODE (decl) != PARM_DECL
	       && TREE_CODE (old) == 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;

	  /* [basic.scope.param] A parameter name shall not be redeclared
	     in the outermost block of the function definition.  */
	  if (b->kind == sk_function_parms)
	    {
	      error_at (DECL_SOURCE_LOCATION (decl),
			"declaration of %q#D shadows a parameter", decl);
	      inform (DECL_SOURCE_LOCATION (old),
		      "%q#D previously declared here", old);
	      return;
	    }
	}

      /* The local structure or class can't use parameters of
	 the containing function anyway.  */
      if (DECL_CONTEXT (old) != current_function_decl)
	{
	  for (cp_binding_level *scope = current_binding_level;
	       scope != old_scope; scope = scope->level_chain)
	    if (scope->kind == sk_class
		&& !LAMBDA_TYPE_P (scope->this_entity))
	      return;
	}
      /* Error if redeclaring a local declared in a
	 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 (VAR_P (old)
	       && old_scope == current_binding_level->level_chain
	       && (old_scope->kind == sk_cond || old_scope->kind == sk_for))
	{
	  auto_diagnostic_group d;
	  error_at (DECL_SOURCE_LOCATION (decl),
		    "redeclaration of %q#D", decl);
	  inform (DECL_SOURCE_LOCATION (old),
		  "%q#D previously declared here", old);
	  return;
	}
      /* C++11:
	 3.3.3/3:  The name declared in an exception-declaration (...)
	 shall not be redeclared in the outermost block of the handler.
	 3.3.3/2:  A parameter name shall not be redeclared (...) in
	 the outermost block of any handler associated with a
	 function-try-block.
	 3.4.1/15: The function parameter names shall not be redeclared
	 in the exception-declaration nor in the outermost block of a
	 handler for the function-try-block.  */
      else if ((TREE_CODE (old) == VAR_DECL
		&& old_scope == current_binding_level->level_chain
		&& old_scope->kind == sk_catch)
	       || (TREE_CODE (old) == PARM_DECL
		   && (current_binding_level->kind == sk_catch
		       || current_binding_level->level_chain->kind == sk_catch)
		   && in_function_try_handler))
	{
	  auto_diagnostic_group d;
	  if (permerror (DECL_SOURCE_LOCATION (decl),
			 "redeclaration of %q#D", decl))
	    inform (DECL_SOURCE_LOCATION (old),
		    "%q#D previously declared here", old);
	  return;
	}

      /* If '-Wshadow=compatible-local' is specified without other
	 -Wshadow= flags, we will warn only when the type of the
	 shadowing variable (DECL) can be converted to that of the
	 shadowed parameter (OLD_LOCAL). The reason why we only check
	 if DECL's type can be converted to OLD_LOCAL's type (but not the
	 other way around) is because when users accidentally shadow a
	 parameter, more than often they would use the variable
	 thinking (mistakenly) it's still the parameter. It would be
	 rare that users would use the variable in the place that
	 expects the parameter but thinking it's a new decl.
	 If either object is a TYPE_DECL, '-Wshadow=compatible-local'
	 warns regardless of whether one of the types involved
	 is a subclass of the other, since that is never okay.  */

      enum opt_code warning_code;
      if (warn_shadow)
	warning_code = OPT_Wshadow;
      else if ((TREE_CODE (decl) == TYPE_DECL)
	       ^ (TREE_CODE (old) == TYPE_DECL))
	/* If exactly one is a type, they aren't compatible.  */
	warning_code = OPT_Wshadow_local;
      else if ((TREE_TYPE (old)
		&& TREE_TYPE (decl)
		&& same_type_p (TREE_TYPE (old), TREE_TYPE (decl)))
	       || TREE_CODE (decl) == TYPE_DECL
	       || TREE_CODE (old) == TYPE_DECL
	       || (!dependent_type_p (TREE_TYPE (decl))
		   && !dependent_type_p (TREE_TYPE (old))
		   /* If the new decl uses auto, we don't yet know
		      its type (the old type cannot be using auto
		      at this point, without also being
		      dependent).  This is an indication we're