path: root/gcc/cp/search.c

/* Breadth-first and depth-first routines for
   searching multiple-inheritance lattice for GNU C++.
   Copyright (C) 1987, 89, 92-97, 1998, 1999, 2000 Free Software Foundation, Inc.
   Contributed by Michael Tiemann (tiemann@cygnus.com)

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC 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 GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* High-level class interface.  */

#include "config.h"
#include "system.h"
#include "tree.h"
#include "cp-tree.h"
#include "obstack.h"
#include "flags.h"
#include "rtl.h"
#include "output.h"
#include "toplev.h"

#define obstack_chunk_alloc xmalloc
#define obstack_chunk_free free

extern struct obstack *current_obstack;

#include "stack.h"

/* Obstack used for remembering decision points of breadth-first.  */

static struct obstack search_obstack;

/* Methods for pushing and popping objects to and from obstacks.  */

struct stack_level *
push_stack_level (obstack, tp, size)
     struct obstack *obstack;
     char *tp;  /* Sony NewsOS 5.0 compiler doesn't like void * here.  */
     int size;
{
  struct stack_level *stack;
  obstack_grow (obstack, tp, size);
  stack = (struct stack_level *) ((char*)obstack_next_free (obstack) - size);
  obstack_finish (obstack);
  stack->obstack = obstack;
  stack->first = (tree *) obstack_base (obstack);
  stack->limit = obstack_room (obstack) / sizeof (tree *);
  return stack;
}

struct stack_level *
pop_stack_level (stack)
     struct stack_level *stack;
{
  struct stack_level *tem = stack;
  struct obstack *obstack = tem->obstack;
  stack = tem->prev;
  obstack_free (obstack, tem);
  return stack;
}

#define search_level stack_level
static struct search_level *search_stack;

static tree next_baselink PARAMS ((tree));
static tree get_vbase_1 PARAMS ((tree, tree, unsigned int *));
static tree lookup_field_1 PARAMS ((tree, tree));
static tree convert_pointer_to_single_level PARAMS ((tree, tree));
static int lookup_fnfields_here PARAMS ((tree, tree));
static int is_subobject_of_p PARAMS ((tree, tree));
static int hides PARAMS ((tree, tree));
static tree virtual_context PARAMS ((tree, tree, tree));
static tree dfs_check_overlap PARAMS ((tree, void *));
static tree dfs_no_overlap_yet PARAMS ((tree, void *));
static int get_base_distance_recursive
	PARAMS ((tree, int, int, int, int *, tree *, tree,
	       int, int *, int, int));
static int dynamic_cast_base_recurse PARAMS ((tree, tree, int, tree *));
static void expand_upcast_fixups 
	PARAMS ((tree, tree, tree, tree, tree, tree, tree *));
static void fixup_virtual_upcast_offsets
	PARAMS ((tree, tree, int, int, tree, tree, tree, tree,
	       tree *));
static tree marked_vtable_pathp PARAMS ((tree, void *));
static tree unmarked_vtable_pathp PARAMS ((tree, void *));
static tree marked_new_vtablep PARAMS ((tree, void *));
static tree unmarked_new_vtablep PARAMS ((tree, void *));
static tree marked_pushdecls_p PARAMS ((tree, void *));
static tree unmarked_pushdecls_p PARAMS ((tree, void *));
#if 0
static tree dfs_debug_unmarkedp PARAMS ((tree, void *));
static tree dfs_debug_mark PARAMS ((tree, void *));
#endif
static tree dfs_find_vbases PARAMS ((tree, void *));
static tree dfs_clear_vbase_slots PARAMS ((tree, void *));
static tree dfs_init_vbase_pointers PARAMS ((tree, void *));
static tree dfs_get_vbase_types PARAMS ((tree, void *));
static tree dfs_push_type_decls PARAMS ((tree, void *));
static tree dfs_push_decls PARAMS ((tree, void *));
static tree dfs_unuse_fields PARAMS ((tree, void *));
static tree add_conversions PARAMS ((tree, void *));
static tree get_virtuals_named_this PARAMS ((tree, tree));
static tree get_virtual_destructor PARAMS ((tree, void *));
static tree tree_has_any_destructor_p PARAMS ((tree, void *));
static int covariant_return_p PARAMS ((tree, tree));
static int check_final_overrider PARAMS ((tree, tree));
static struct search_level *push_search_level
	PARAMS ((struct stack_level *, struct obstack *));
static struct search_level *pop_search_level
	PARAMS ((struct stack_level *));
static tree bfs_walk
	PARAMS ((tree, tree (*) (tree, void *), tree (*) (tree, void *),
	       void *));
static tree lookup_field_queue_p PARAMS ((tree, void *));
static tree lookup_field_r PARAMS ((tree, void *));
static tree get_virtuals_named_this_r PARAMS ((tree, void *));
static tree context_for_name_lookup PARAMS ((tree));
static tree canonical_binfo PARAMS ((tree));
static tree shared_marked_p PARAMS ((tree, void *));
static tree shared_unmarked_p PARAMS ((tree, void *));
static int  dependent_base_p PARAMS ((tree));
static tree dfs_accessible_queue_p PARAMS ((tree, void *));
static tree dfs_accessible_p PARAMS ((tree, void *));
static tree dfs_access_in_type PARAMS ((tree, void *));
static tree access_in_type PARAMS ((tree, tree));
static tree dfs_canonical_queue PARAMS ((tree, void *));
static tree dfs_assert_unmarked_p PARAMS ((tree, void *));
static void assert_canonical_unmarked PARAMS ((tree));
static int protected_accessible_p PARAMS ((tree, tree, tree, tree));
static int friend_accessible_p PARAMS ((tree, tree, tree, tree));
static void setup_class_bindings PARAMS ((tree, int));
static int template_self_reference_p PARAMS ((tree, tree));
static void fixup_all_virtual_upcast_offsets PARAMS ((tree, tree));
static tree dfs_mark_primary_bases PARAMS ((tree, void *));
static tree get_shared_vbase_if_not_primary PARAMS ((tree, void *));
static tree dfs_find_vbase_instance PARAMS ((tree, void *));
static tree dfs_get_pure_virtuals PARAMS ((tree, void *));

/* Allocate a level of searching.  */

static struct search_level *
push_search_level (stack, obstack)
     struct stack_level *stack;
     struct obstack *obstack;
{
  struct search_level tem;

  tem.prev = stack;
  return push_stack_level (obstack, (char *)&tem, sizeof (tem));
}

/* Discard a level of search allocation.  */

static struct search_level *
pop_search_level (obstack)
     struct stack_level *obstack;
{
  register struct search_level *stack = pop_stack_level (obstack);

  return stack;
}

/* Variables for gathering statistics.  */
#ifdef GATHER_STATISTICS
static int n_fields_searched;
static int n_calls_lookup_field, n_calls_lookup_field_1;
static int n_calls_lookup_fnfields, n_calls_lookup_fnfields_1;
static int n_calls_get_base_type;
static int n_outer_fields_searched;
static int n_contexts_saved;
#endif /* GATHER_STATISTICS */


/* Get a virtual binfo that is found inside BINFO's hierarchy that is
   the same type as the type given in PARENT.  To be optimal, we want
   the first one that is found by going through the least number of
   virtual bases.

   This uses a clever algorithm that updates *depth when we find the vbase,
   and cuts off other paths of search when they reach that depth.  */

static tree
get_vbase_1 (parent, binfo, depth)
     tree parent, binfo;
     unsigned int *depth;
{
  tree binfos;
  int i, n_baselinks;
  tree rval = NULL_TREE;

  if (BINFO_TYPE (binfo) == parent && TREE_VIA_VIRTUAL (binfo))
    {
      *depth = 0;
      return binfo;
    }

  *depth = *depth - 1;

  binfos = BINFO_BASETYPES (binfo);
  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;

  /* Process base types.  */
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      tree nrval;

      if (*depth == 0)
	break;

      nrval = get_vbase_1 (parent, base_binfo, depth);
      if (nrval)
	rval = nrval;
    }
  *depth = *depth+1;
  return rval;
}

/* Return the shortest path to vbase PARENT within BINFO, ignoring
   access and ambiguity.  */

tree
get_vbase (parent, binfo)
     tree parent;
     tree binfo;
{
  unsigned int d = (unsigned int)-1;
  return get_vbase_1 (parent, binfo, &d);
}

/* Convert EXPR to a virtual base class of type TYPE.  We know that
   EXPR is a non-null POINTER_TYPE to RECORD_TYPE.  We also know that
   the type of what expr points to has a virtual base of type TYPE.  */

tree
convert_pointer_to_vbase (type, expr)
     tree type;
     tree expr;
{
  tree vb = get_vbase (type, TYPE_BINFO (TREE_TYPE (TREE_TYPE (expr))));
  return convert_pointer_to_real (vb, expr);
}

/* Check whether the type given in BINFO is derived from PARENT.  If
   it isn't, return 0.  If it is, but the derivation is MI-ambiguous
   AND protect != 0, emit an error message and return error_mark_node.

   Otherwise, if TYPE is derived from PARENT, return the actual base
   information, unless a one of the protection violations below
   occurs, in which case emit an error message and return error_mark_node.

   If PROTECT is 1, then check if access to a public field of PARENT
   would be private.  Also check for ambiguity.  */

tree
get_binfo (parent, binfo, protect)
     register tree parent, binfo;
     int protect;
{
  tree type = NULL_TREE;
  int dist;
  tree rval = NULL_TREE;
  
  if (TREE_CODE (parent) == TREE_VEC)
    parent = BINFO_TYPE (parent);
  else if (! IS_AGGR_TYPE_CODE (TREE_CODE (parent)))
    my_friendly_abort (89);

  if (TREE_CODE (binfo) == TREE_VEC)
    type = BINFO_TYPE (binfo);
  else if (IS_AGGR_TYPE_CODE (TREE_CODE (binfo)))
    type = binfo;
  else
    my_friendly_abort (90);
  
  dist = get_base_distance (parent, binfo, protect, &rval);

  if (dist == -3)
    {
      cp_error ("fields of `%T' are inaccessible in `%T' due to private inheritance",
		parent, type);
      return error_mark_node;
    }
  else if (dist == -2 && protect)
    {
      cp_error ("type `%T' is ambiguous base class for type `%T'", parent,
		type);
      return error_mark_node;
    }

  return rval;
}

/* This is the newer depth first get_base_distance routine.  */

static int
get_base_distance_recursive (binfo, depth, is_private, rval,
			     rval_private_ptr, new_binfo_ptr, parent,
			     protect, via_virtual_ptr, via_virtual,
			     current_scope_in_chain)
     tree binfo;
     int depth, is_private, rval;
     int *rval_private_ptr;
     tree *new_binfo_ptr, parent;
     int protect, *via_virtual_ptr, via_virtual;
     int current_scope_in_chain;
{
  tree binfos;
  int i, n_baselinks;

  if (protect
      && !current_scope_in_chain
      && is_friend (BINFO_TYPE (binfo), current_scope ()))
    current_scope_in_chain = 1;

  if (BINFO_TYPE (binfo) == parent || binfo == parent)
    {
      int better = 0;

      if (rval == -1)
	/* This is the first time we've found parent.  */
	better = 1;
      else if (tree_int_cst_equal (BINFO_OFFSET (*new_binfo_ptr),
				   BINFO_OFFSET (binfo))
	       && *via_virtual_ptr && via_virtual)
	{
	  /* A new path to the same vbase.  If this one has better
	     access or is shorter, take it.  */

	  if (protect)
	    better = *rval_private_ptr - is_private;
	  if (better == 0)
	    better = rval - depth;
	}
      else
	{
	  /* Ambiguous base class.  */
	  rval = depth = -2;

	  /* If we get an ambiguity between virtual and non-virtual base
	     class, return the non-virtual in case we are ignoring
	     ambiguity.  */
	  better = *via_virtual_ptr - via_virtual;
	}

      if (better > 0)
	{
	  rval = depth;
	  *rval_private_ptr = is_private;
	  *new_binfo_ptr = binfo;
	  *via_virtual_ptr = via_virtual;
	}

      return rval;
    }

  binfos = BINFO_BASETYPES (binfo);
  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;
  depth += 1;

  /* Process base types.  */
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);

      int via_private
	= (protect
	   && (is_private
	       || (!TREE_VIA_PUBLIC (base_binfo)
		   && !(TREE_VIA_PROTECTED (base_binfo)
			&& current_scope_in_chain)
		   && !is_friend (BINFO_TYPE (binfo), current_scope ()))));
      int this_virtual = via_virtual || TREE_VIA_VIRTUAL (base_binfo);

      rval = get_base_distance_recursive (base_binfo, depth, via_private,
					  rval, rval_private_ptr,
					  new_binfo_ptr, parent,
					  protect, via_virtual_ptr,
					  this_virtual,
					  current_scope_in_chain);

      /* If we've found a non-virtual, ambiguous base class, we don't need
	 to keep searching.  */
      if (rval == -2 && *via_virtual_ptr == 0)
	return rval;
    }

  return rval;
}

/* Return the number of levels between type PARENT and the type given
   in BINFO, following the leftmost path to PARENT not found along a
   virtual path, if there are no real PARENTs (all come from virtual
   base classes), then follow the shortest public path to PARENT.

   Return -1 if TYPE is not derived from PARENT.
   Return -2 if PARENT is an ambiguous base class of TYPE, and PROTECT is
    non-negative.
   Return -3 if PARENT is private to TYPE, and PROTECT is non-zero.

   If PATH_PTR is non-NULL, then also build the list of types
   from PARENT to TYPE, with TREE_VIA_VIRTUAL and TREE_VIA_PUBLIC
   set.

   PARENT can also be a binfo, in which case that exact parent is found
   and no other.  convert_pointer_to_real uses this functionality.

   If BINFO is a binfo, its BINFO_INHERITANCE_CHAIN will be left alone.  */

int
get_base_distance (parent, binfo, protect, path_ptr)
     register tree parent, binfo;
     int protect;
     tree *path_ptr;
{
  int rval;
  int rval_private = 0;
  tree type = NULL_TREE;
  tree new_binfo = NULL_TREE;
  int via_virtual;
  int watch_access = protect;

  /* Should we be completing types here?  */
  if (TREE_CODE (parent) != TREE_VEC)
    parent = complete_type (TYPE_MAIN_VARIANT (parent));
  else
    complete_type (TREE_TYPE (parent));

  if (TREE_CODE (binfo) == TREE_VEC)
    type = BINFO_TYPE (binfo);
  else if (IS_AGGR_TYPE_CODE (TREE_CODE (binfo)))
    {
      type = complete_type (binfo);
      binfo = TYPE_BINFO (type);

      if (path_ptr)
	my_friendly_assert (BINFO_INHERITANCE_CHAIN (binfo) == NULL_TREE,
			    980827);
    }
  else
    my_friendly_abort (92);

  if (parent == type || parent == binfo)
    {
      /* If the distance is 0, then we don't really need
	 a path pointer, but we shouldn't let garbage go back.  */
      if (path_ptr)
	*path_ptr = binfo;
      return 0;
    }

  if (path_ptr)
    watch_access = 1;

  rval = get_base_distance_recursive (binfo, 0, 0, -1,
				      &rval_private, &new_binfo, parent,
				      watch_access, &via_virtual, 0,
				      0);

  /* Access restrictions don't count if we found an ambiguous basetype.  */
  if (rval == -2 && protect >= 0)
    rval_private = 0;

  if (rval && protect && rval_private)
    return -3;

  /* If they gave us the real vbase binfo, which isn't in the main binfo
     tree, deal with it.  This happens when we are called from
     expand_upcast_fixups.  */
  if (rval == -1 && TREE_CODE (parent) == TREE_VEC
      && parent == BINFO_FOR_VBASE (BINFO_TYPE (parent), type))
    {
      my_friendly_assert (BINFO_INHERITANCE_CHAIN (parent) == binfo, 980827);
      new_binfo = parent;
      rval = 1;
    }

  if (path_ptr)
    *path_ptr = new_binfo;
  return rval;
}

/* Worker function for get_dynamic_cast_base_type.  */

static int
dynamic_cast_base_recurse (subtype, binfo, via_virtual, offset_ptr)
     tree subtype;
     tree binfo;
     int via_virtual;
     tree *offset_ptr;
{
  tree binfos;
  int i, n_baselinks;
  int worst = -2;
  
  if (BINFO_TYPE (binfo) == subtype)
    {
      if (via_virtual)
        return -1;
      else
        {
          *offset_ptr = BINFO_OFFSET (binfo);
          return 0;
        }
    }
  
  binfos = BINFO_BASETYPES (binfo);
  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      int rval;
      
      if (!TREE_VIA_PUBLIC (base_binfo))
        continue;
      rval = dynamic_cast_base_recurse
             (subtype, base_binfo,
              via_virtual || TREE_VIA_VIRTUAL (base_binfo), offset_ptr);
      if (worst == -2)
        worst = rval;
      else if (rval >= 0)
        worst = worst >= 0 ? -3 : worst;
      else if (rval == -1)
        worst = -1;
      else if (rval == -3 && worst != -1)
        worst = -3;
    }
  return worst;
}

/* The dynamic cast runtime needs a hint about how the static SUBTYPE type
   started from is related to the required TARGET type, in order to optimize
   the inheritance graph search. This information is independant of the
   current context, and ignores private paths, hence get_base_distance is
   inappropriate. Return a TREE specifying the base offset, BOFF.
   BOFF >= 0, there is only one public non-virtual SUBTYPE base at offset BOFF,
      and there are no public virtual SUBTYPE bases.
   BOFF == -1, SUBTYPE occurs as multiple public virtual or non-virtual bases.
   BOFF == -2, SUBTYPE is not a public base.
   BOFF == -3, SUBTYPE occurs as multiple public non-virtual bases.  */

tree
get_dynamic_cast_base_type (subtype, target)
     tree subtype;
     tree target;
{
  tree offset = NULL_TREE;
  int boff = dynamic_cast_base_recurse (subtype, TYPE_BINFO (target),
                                        0, &offset);
  
  if (!boff)
    return offset;
  return build_int_2 (boff, -1);
}

/* Search for a member with name NAME in a multiple inheritance lattice
   specified by TYPE.  If it does not exist, return NULL_TREE.
   If the member is ambiguously referenced, return `error_mark_node'.
   Otherwise, return the FIELD_DECL.  */

/* Do a 1-level search for NAME as a member of TYPE.  The caller must
   figure out whether it can access this field.  (Since it is only one
   level, this is reasonable.)  */

static tree
lookup_field_1 (type, name)
     tree type, name;
{
  register tree field;

  if (TREE_CODE (type) == TEMPLATE_TYPE_PARM
      || TREE_CODE (type) == TEMPLATE_TEMPLATE_PARM)
    /* The TYPE_FIELDS of a TEMPLATE_TYPE_PARM are not fields at all;
       instead TYPE_FIELDS is the TEMPLATE_PARM_INDEX.  (Miraculously,
       the code often worked even when we treated the index as a list
       of fields!)  */
    return NULL_TREE;

  if (TYPE_NAME (type)
      && DECL_LANG_SPECIFIC (TYPE_NAME (type))
      && DECL_SORTED_FIELDS (TYPE_NAME (type)))
    {
      tree *fields = &TREE_VEC_ELT (DECL_SORTED_FIELDS (TYPE_NAME (type)), 0);
      int lo = 0, hi = TREE_VEC_LENGTH (DECL_SORTED_FIELDS (TYPE_NAME (type)));
      int i;

      while (lo < hi)
	{
	  i = (lo + hi) / 2;

#ifdef GATHER_STATISTICS
	  n_fields_searched++;
#endif /* GATHER_STATISTICS */

	  if (DECL_NAME (fields[i]) > name)
	    hi = i;
	  else if (DECL_NAME (fields[i]) < name)
	    lo = i + 1;
	  else
	    {
	      /* We might have a nested class and a field with the
		 same name; we sorted them appropriately via
		 field_decl_cmp, so just look for the last field with
		 this name.  */
	      while (i + 1 < hi
		     && DECL_NAME (fields[i+1]) == name)
		++i;
	      return fields[i];
	    }
	}
      return NULL_TREE;
    }

  field = TYPE_FIELDS (type);

#ifdef GATHER_STATISTICS
  n_calls_lookup_field_1++;
#endif /* GATHER_STATISTICS */
  while (field)
    {
#ifdef GATHER_STATISTICS
      n_fields_searched++;
#endif /* GATHER_STATISTICS */
      my_friendly_assert (TREE_CODE_CLASS (TREE_CODE (field)) == 'd', 0);
      if (DECL_NAME (field) == NULL_TREE
	  && ANON_AGGR_TYPE_P (TREE_TYPE (field)))
	{
	  tree temp = lookup_field_1 (TREE_TYPE (field), name);
	  if (temp)
	    return temp;
	}
      if (TREE_CODE (field) == USING_DECL)
	/* For now, we're just treating member using declarations as
	   old ARM-style access declarations.  Thus, there's no reason
	   to return a USING_DECL, and the rest of the compiler can't
	   handle it.  Once the class is defined, these are purged
	   from TYPE_FIELDS anyhow; see handle_using_decl.  */
	;
      else if (DECL_NAME (field) == name)
	{
	  if ((TREE_CODE(field) == VAR_DECL || TREE_CODE(field) == CONST_DECL)
	      && DECL_ASSEMBLER_NAME (field) != NULL)
	    GNU_xref_ref(current_function_decl,
			 IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (field)));
	  return field;
	}
      field = TREE_CHAIN (field);
    }
  /* Not found.  */
  if (name == vptr_identifier)
    {
      /* Give the user what s/he thinks s/he wants.  */
      if (TYPE_POLYMORPHIC_P (type))
	return TYPE_VFIELD (type);
    }
  return NULL_TREE;
}

/* There are a number of cases we need to be aware of here:
			 current_class_type	current_function_decl
     global			NULL			NULL
     fn-local			NULL			SET
     class-local		SET			NULL
     class->fn			SET			SET
     fn->class			SET			SET

   Those last two make life interesting.  If we're in a function which is
   itself inside a class, we need decls to go into the fn's decls (our
   second case below).  But if we're in a class and the class itself is
   inside a function, we need decls to go into the decls for the class.  To
   achieve this last goal, we must see if, when both current_class_ptr and
   current_function_decl are set, the class was declared inside that
   function.  If so, we know to put the decls into the class's scope.  */

tree
current_scope ()
{
  if (current_function_decl == NULL_TREE)
    return current_class_type;
  if (current_class_type == NULL_TREE)
    return current_function_decl;
  if ((DECL_FUNCTION_MEMBER_P (current_function_decl)
       && same_type_p (DECL_CONTEXT (current_function_decl),
		       current_class_type))
      || (DECL_FRIEND_CONTEXT (current_function_decl)
	  && same_type_p (DECL_FRIEND_CONTEXT (current_function_decl),
			  current_class_type)))
    return current_function_decl;

  return current_class_type;
}

/* Returns non-zero if we are currently in a function scope.  Note
   that this function returns zero if we are within a local class, but
   not within a member function body of the local class.  */

int
at_function_scope_p ()
{
  tree cs = current_scope ();
  return cs && TREE_CODE (cs) == FUNCTION_DECL;
}

/* Return the scope of DECL, as appropriate when doing name-lookup.  */

static tree
context_for_name_lookup (decl)
     tree decl;
{
  /* [class.union]
     
     For the purposes of name lookup, after the anonymous union
     definition, the members of the anonymous union are considered to
     have been defined in the scope in which teh anonymous union is
     declared.  */ 
  tree context = CP_DECL_CONTEXT (decl);

  while (TYPE_P (context) && ANON_AGGR_TYPE_P (context))
    context = TYPE_CONTEXT (context);
  if (!context)
    context = global_namespace;

  return context;
}

/* Return a canonical BINFO if BINFO is a virtual base, or just BINFO
   otherwise.  */

static tree
canonical_binfo (binfo)
     tree binfo;
{
  return (TREE_VIA_VIRTUAL (binfo)
	  ? TYPE_BINFO (BINFO_TYPE (binfo)) : binfo);
}

/* A queue function that simply ensures that we walk into the
   canonical versions of virtual bases.  */

static tree
dfs_canonical_queue (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  return canonical_binfo (binfo);
}

/* Called via dfs_walk from assert_canonical_unmarked.  */

static tree
dfs_assert_unmarked_p (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  my_friendly_assert (!BINFO_MARKED (binfo), 0);
  return NULL_TREE;
}

/* Asserts that all the nodes below BINFO (using the canonical
   versions of virtual bases) are unmarked.  */

static void
assert_canonical_unmarked (binfo)
     tree binfo;
{
  dfs_walk (binfo, dfs_assert_unmarked_p, dfs_canonical_queue, 0);
}

/* If BINFO is marked, return a canonical version of BINFO.
   Otherwise, return NULL_TREE.  */

static tree
shared_marked_p (binfo, data)
     tree binfo;
     void *data;
{
  binfo = canonical_binfo (binfo);
  return markedp (binfo, data);
}

/* If BINFO is not marked, return a canonical version of BINFO.
   Otherwise, return NULL_TREE.  */

static tree
shared_unmarked_p (binfo, data)
     tree binfo;
     void *data;
{
  binfo = canonical_binfo (binfo);
  return unmarkedp (binfo, data);
}

/* Called from access_in_type via dfs_walk.  Calculate the access to
   DATA (which is really a DECL) in BINFO.  */

static tree
dfs_access_in_type (binfo, data)
     tree binfo;
     void *data;
{
  tree decl = (tree) data;
  tree type = BINFO_TYPE (binfo);
  tree access = NULL_TREE;

  if (context_for_name_lookup (decl) == type)
    {
      /* If we have desceneded to the scope of DECL, just note the
	 appropriate access.  */
      if (TREE_PRIVATE (decl))
	access = access_private_node;
      else if (TREE_PROTECTED (decl))
	access = access_protected_node;
      else
	access = access_public_node;
    }
  else 
    {
      /* First, check for an access-declaration that gives us more
	 access to the DECL.  The CONST_DECL for an enumeration
	 constant will not have DECL_LANG_SPECIFIC, and thus no
	 DECL_ACCESS.  */
      if (DECL_LANG_SPECIFIC (decl))
	{
	  access = purpose_member (type, DECL_ACCESS (decl));
	  if (access)
	    access = TREE_VALUE (access);
	}

      if (!access)
	{
	  int i;
	  int n_baselinks;
	  tree binfos;
	  
	  /* Otherwise, scan our baseclasses, and pick the most favorable
	     access.  */
	  binfos = BINFO_BASETYPES (binfo);
	  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;
	  for (i = 0; i < n_baselinks; ++i)
	    {
	      tree base_binfo = TREE_VEC_ELT (binfos, i);
	      tree base_access = TREE_CHAIN (canonical_binfo (base_binfo));

	      if (!base_access || base_access == access_private_node)
		/* If it was not accessible in the base, or only
		   accessible as a private member, we can't access it
		   all.  */
		base_access = NULL_TREE;
	      else if (TREE_VIA_PROTECTED (base_binfo))
		/* Public and protected members in the base are
		   protected here.  */
		base_access = access_protected_node;
	      else if (!TREE_VIA_PUBLIC (base_binfo))
		/* Public and protected members in the base are
		   private here.  */
		base_access = access_private_node;

	      /* See if the new access, via this base, gives more
		 access than our previous best access.  */
	      if (base_access &&
		  (base_access == access_public_node
		   || (base_access == access_protected_node
		       && access != access_public_node)
		   || (base_access == access_private_node
		       && !access)))
		{
		  access = base_access;

		  /* If the new access is public, we can't do better.  */
		  if (access == access_public_node)
		    break;
		}
	    }
	}
    }

  /* Note the access to DECL in TYPE.  */
  TREE_CHAIN (binfo) = access;

  /* Mark TYPE as visited so that if we reach it again we do not
     duplicate our efforts here.  */
  SET_BINFO_MARKED (binfo);

  return NULL_TREE;
}

/* Return the access to DECL in TYPE.  */

static tree 
access_in_type (type, decl)
     tree type;
     tree decl;
{
  tree binfo = TYPE_BINFO (type);

  /* We must take into account

       [class.paths]

       If a name can be reached by several paths through a multiple
       inheritance graph, the access is that of the path that gives
       most access.  

    The algorithm we use is to make a post-order depth-first traversal
    of the base-class hierarchy.  As we come up the tree, we annotate
    each node with the most lenient access.  */
  dfs_walk_real (binfo, 0, dfs_access_in_type, shared_unmarked_p, decl);
  dfs_walk (binfo, dfs_unmark, shared_marked_p,  0);
  assert_canonical_unmarked (binfo);

  return TREE_CHAIN (binfo);
}

/* Called from dfs_accessible_p via dfs_walk.  */

static tree
dfs_accessible_queue_p (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  if (BINFO_MARKED (binfo))
    return NULL_TREE;

  /* If this class is inherited via private or protected inheritance,
     then we can't see it, unless we are a friend of the subclass.  */
  if (!TREE_VIA_PUBLIC (binfo)
      && !is_friend (BINFO_TYPE (BINFO_INHERITANCE_CHAIN (binfo)),
		     current_scope ()))
    return NULL_TREE;

  return canonical_binfo (binfo);
}

/* Called from dfs_accessible_p via dfs_walk.  */

static tree
dfs_accessible_p (binfo, data)
     tree binfo;
     void *data;
{
  int protected_ok = data != 0;
  tree access;

  /* We marked the binfos while computing the access in each type.
     So, we unmark as we go now.  */
  SET_BINFO_MARKED (binfo);

  access = TREE_CHAIN (binfo);
  if (access == access_public_node
      || (access == access_protected_node && protected_ok))
    return binfo;
  else if (access && is_friend (BINFO_TYPE (binfo), current_scope ()))
    return binfo;

  return NULL_TREE;
}

/* Returns non-zero if it is OK to access DECL when named in TYPE
   through an object indiated by BINFO in the context of DERIVED.  */

static int
protected_accessible_p (type, decl, derived, binfo)
     tree type;
     tree decl;
     tree derived;
     tree binfo;
{
  tree access;

  /* We're checking this clause from [class.access.base]

       m as a member of N is protected, and the reference occurs in a
       member or friend of class N, or in a member or friend of a
       class P derived from N, where m as a member of P is private or
       protected.  

    If DERIVED isn't derived from TYPE, then it certainly does not
    apply.  */
  if (!DERIVED_FROM_P (type, derived))
    return 0;

  access = access_in_type (derived, decl);
  if (same_type_p (derived, type))
    {
      if (access != access_private_node)
	return 0;
    }
  else if (access != access_private_node
	   && access != access_protected_node)
    return 0;
  
  /* [class.protected]

     When a friend or a member function of a derived class references
     a protected nonstatic member of a base class, an access check
     applies in addition to those described earlier in clause
     _class.access_.4) Except when forming a pointer to member
     (_expr.unary.op_), the access must be through a pointer to,
     reference to, or object of the derived class itself (or any class
     derived from that class) (_expr.ref_).  If the access is to form
     a pointer to member, the nested-name-specifier shall name the
     derived class (or any class derived from that class).  */
  if (DECL_NONSTATIC_MEMBER_P (decl))
    {
      /* We can tell through what the reference is occurring by
	 chasing BINFO up to the root.  */
      tree t = binfo;
      while (BINFO_INHERITANCE_CHAIN (t))
	t = BINFO_INHERITANCE_CHAIN (t);
      
      if (!DERIVED_FROM_P (derived, BINFO_TYPE (t)))
	return 0;
    }

  return 1;
}

/* Returns non-zero if SCOPE is a friend of a type which would be able
   to acces DECL, named in TYPE, through the object indicated by
   BINFO.  */

static int
friend_accessible_p (scope, type, decl, binfo)
     tree scope;
     tree type;
     tree decl;
     tree binfo;
{
  tree befriending_classes;
  tree t;

  if (!scope)
    return 0;

  if (TREE_CODE (scope) == FUNCTION_DECL
      || DECL_FUNCTION_TEMPLATE_P (scope))
    befriending_classes = DECL_BEFRIENDING_CLASSES (scope);
  else if (TYPE_P (scope))
    befriending_classes = CLASSTYPE_BEFRIENDING_CLASSES (scope);
  else
    return 0;

  for (t = befriending_classes; t; t = TREE_CHAIN (t))
    if (protected_accessible_p (type, decl, TREE_VALUE (t), binfo))
      return 1;

  /* Nested classes are implicitly friends of their enclosing types, as
     per core issue 45 (this is a change from the standard).  */
  if (TYPE_P (scope))
    for (t = TYPE_CONTEXT (scope); t && TYPE_P (t); t = TYPE_CONTEXT (t))
      if (protected_accessible_p (type, decl, t, binfo))
	return 1;

  if (TREE_CODE (scope) == FUNCTION_DECL
      || DECL_FUNCTION_TEMPLATE_P (scope))
    {
      /* Perhaps this SCOPE is a member of a class which is a 
	 friend.  */ 
      if (DECL_CLASS_SCOPE_P (decl)
	  && friend_accessible_p (DECL_CONTEXT (scope), type,
				  decl, binfo))
	return 1;

      /* Or an instantiation of something which is a friend.  */
      if (DECL_TEMPLATE_INFO (scope))
	return friend_accessible_p (DECL_TI_TEMPLATE (scope),
				    type, decl, binfo);
    }
  else if (CLASSTYPE_TEMPLATE_INFO (scope))
    return friend_accessible_p (CLASSTYPE_TI_TEMPLATE (scope),
				type, decl, binfo);

  return 0;
}

/* Perform access control on TYPE_DECL VAL, which was looked up in TYPE.
   This is fairly complex, so here's the design:

   The lang_extdef nonterminal sets type_lookups to NULL_TREE before we
     start to process a top-level declaration.
   As we process the decl-specifier-seq for the declaration, any types we
     see that might need access control are passed to type_access_control,
     which defers checking by adding them to type_lookups.
   When we are done with the decl-specifier-seq, we record the lookups we've
     seen in the lookups field of the typed_declspecs nonterminal.
   When we process the first declarator, either in parse_decl or
     begin_function_definition, we call initial_deferred_type_access_control,
     which processes any lookups from within that declarator, stores the
     lookups from the decl-specifier-seq in current_type_lookups, and sets
     type_lookups to error_mark_node.
   Subsequent declarators process current_type_lookups again to make sure
     that the types are accessible to all of the declarators.  Any lookups
     within subsequent declarators are processed immediately.
   Within a function, type_lookups is error_mark_node, so all lookups are
     processed immediately.  */

void
type_access_control (type, val)
     tree type, val;
{
  if (val == NULL_TREE || TREE_CODE (val) != TYPE_DECL
      || ! DECL_CLASS_SCOPE_P (val))
    return;

  if (type_lookups == error_mark_node)
    enforce_access (type, val);
  else if (! accessible_p (type, val))
    type_lookups = tree_cons (type, val, type_lookups);
}

/* DECL is a declaration from a base class of TYPE, which was the
   class used to name DECL.  Return non-zero if, in the current
   context, DECL is accessible.  If TYPE is actually a BINFO node,
   then we can tell in what context the access is occurring by looking
   at the most derived class along the path indicated by BINFO.  */

int 
accessible_p (type, decl)
     tree type;
     tree decl;
     
{
  tree binfo;
  tree t;

  /* Non-zero if it's OK to access DECL if it has protected
     accessibility in TYPE.  */
  int protected_ok = 0;

  /* If we're not checking access, everything is accessible.  */
  if (!flag_access_control)
    return 1;

  /* If this declaration is in a block or namespace scope, there's no
     access control.  */
  if (!TYPE_P (context_for_name_lookup (decl)))
    return 1;

  if (!TYPE_P (type))
    {
      binfo = type;
      type = BINFO_TYPE (type);
    }
  else
    binfo = TYPE_BINFO (type);

  /* [class.access.base]

     A member m is accessible when named in class N if

     --m as a member of N is public, or

     --m as a member of N is private, and the reference occurs in a
       member or friend of class N, or

     --m as a member of N is protected, and the reference occurs in a
       member or friend of class N, or in a member or friend of a
       class P derived from N, where m as a member of P is private or
       protected, or

     --there exists a base class B of N that is accessible at the point
       of reference, and m is accessible when named in class B.  

    We walk the base class hierarchy, checking these conditions.  */

  /* Figure out where the reference is occurring.  Check to see if
     DECL is private or protected in this scope, since that will
     determine whether protected access in TYPE allowed.  */
  if (current_class_type)
    protected_ok 
      = protected_accessible_p (type, decl, current_class_type,
				binfo);

  /* Now, loop through the classes of which we are a friend.  */
  if (!protected_ok)
    protected_ok = friend_accessible_p (current_scope (),
					type, decl, binfo);

  /* Standardize the binfo that access_in_type will use.  We don't
     need to know what path was chosen from this point onwards.  */
  binfo = TYPE_BINFO (type);

  /* Compute the accessibility of DECL in the class hierarchy
     dominated by type.  */
  access_in_type (type, decl);
  /* Walk the hierarchy again, looking for a base class that allows
     access.  */
  t = dfs_walk (binfo, dfs_accessible_p, 
		dfs_accessible_queue_p,
		protected_ok ? &protected_ok : 0);
  /* Clear any mark bits.  Note that we have to walk the whole tree
     here, since we have aborted the previous walk from some point
     deep in the tree.  */
  dfs_walk (binfo, dfs_unmark, dfs_canonical_queue,  0);
  assert_canonical_unmarked (binfo);

  return t != NULL_TREE;
}

/* Routine to see if the sub-object denoted by the binfo PARENT can be
   found as a base class and sub-object of the object denoted by
   BINFO.  This routine relies upon binfos not being shared, except
   for binfos for virtual bases.  */

static int
is_subobject_of_p (parent, binfo)
     tree parent, binfo;
{
  tree binfos;
  int i, n_baselinks;

  /* We want to canonicalize for comparison purposes.  But, when we
     iterate through basetypes later, we want the binfos from the
     original hierarchy.  That's why we have to calculate BINFOS
     first, and then canonicalize.  */
  binfos = BINFO_BASETYPES (binfo);
  parent = canonical_binfo (parent);
  binfo = canonical_binfo (binfo);

  if (parent == binfo)
    return 1;

  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;

  /* Process and/or queue base types.  */
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      if (!CLASS_TYPE_P (TREE_TYPE (base_binfo)))
	/* If we see a TEMPLATE_TYPE_PARM, or some such, as a base
	   class there's no way to descend into it.  */
	continue;

      if (is_subobject_of_p (parent, base_binfo))
	return 1;
    }
  return 0;
}

/* See if a one FIELD_DECL hides another.  This routine is meant to
   correspond to ANSI working paper Sept 17, 1992 10p4.  The two
   binfos given are the binfos corresponding to the particular places
   the FIELD_DECLs are found.  This routine relies upon binfos not
   being shared, except for virtual bases.  */

static int
hides (hider_binfo, hidee_binfo)
     tree hider_binfo, hidee_binfo;
{
  /* hider hides hidee, if hider has hidee as a base class and
     the instance of hidee is a sub-object of hider.  The first
     part is always true is the second part is true.

     When hider and hidee are the same (two ways to get to the exact
     same member) we consider either one as hiding the other.  */
  return is_subobject_of_p (hidee_binfo, hider_binfo);
}

/* Very similar to lookup_fnfields_1 but it ensures that at least one
   function was declared inside the class given by TYPE.  It really should
   only return functions that match the given TYPE.  */

static int
lookup_fnfields_here (type, name)
     tree type, name;
{
  int idx = lookup_fnfields_1 (type, name);
  tree fndecls;

  /* ctors and dtors are always only in the right class.  */
  if (idx <= 1)
    return idx;
  fndecls = TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type), idx);
  while (fndecls)
    {
      if (TYPE_MAIN_VARIANT (DECL_CONTEXT (OVL_CURRENT (fndecls)))
	  == TYPE_MAIN_VARIANT (type))
	return idx;
      fndecls = OVL_CHAIN (fndecls);
    }
  return -1;
}

struct lookup_field_info {
  /* The type in which we're looking.  */
  tree type;
  /* The name of the field for which we're looking.  */
  tree name;
  /* If non-NULL, the current result of the lookup.  */
  tree rval;
  /* The path to RVAL.  */
  tree rval_binfo;
  /* If non-NULL, the lookup was ambiguous, and this is a list of the
     candidates.  */
  tree ambiguous;
  /* If non-zero, we are looking for types, not data members.  */
  int want_type;
  /* If non-zero, RVAL was found by looking through a dependent base.  */
  int from_dep_base_p;
  /* If something went wrong, a message indicating what.  */
  const char *errstr;
};

/* Returns non-zero if BINFO is not hidden by the value found by the
   lookup so far.  If BINFO is hidden, then there's no need to look in
   it.  DATA is really a struct lookup_field_info.  Called from
   lookup_field via breadth_first_search.  */

static tree
lookup_field_queue_p (binfo, data)
     tree binfo;
     void *data;
{
  struct lookup_field_info *lfi = (struct lookup_field_info *) data;

  /* Don't look for constructors or destructors in base classes.  */
  if (lfi->name == ctor_identifier || lfi->name == dtor_identifier)
    return NULL_TREE;

  /* If this base class is hidden by the best-known value so far, we
     don't need to look.  */
  if (!lfi->from_dep_base_p && lfi->rval_binfo
      && hides (lfi->rval_binfo, binfo))
    return NULL_TREE;

  if (TREE_VIA_VIRTUAL (binfo))
    return BINFO_FOR_VBASE (BINFO_TYPE (binfo), lfi->type);
  else
    return binfo;
}

/* Within the scope of a template class, you can refer to the to the
   current specialization with the name of the template itself.  For
   example:
   
     template <typename T> struct S { S* sp; }

   Returns non-zero if DECL is such a declaration in a class TYPE.  */

static int
template_self_reference_p (type, decl)
     tree type;
     tree decl;
{
  return  (CLASSTYPE_USE_TEMPLATE (type)
	   && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (type))
	   && TREE_CODE (decl) == TYPE_DECL
	   && DECL_ARTIFICIAL (decl)
	   && DECL_NAME (decl) == constructor_name (type));
}

/* DATA is really a struct lookup_field_info.  Look for a field with
   the name indicated there in BINFO.  If this function returns a
   non-NULL value it is the result of the lookup.  Called from
   lookup_field via breadth_first_search.  */

static tree
lookup_field_r (binfo, data)
     tree binfo;
     void *data;
{
  struct lookup_field_info *lfi = (struct lookup_field_info *) data;
  tree type = BINFO_TYPE (binfo);
  tree nval = NULL_TREE;
  int from_dep_base_p;

  /* First, look for a function.  There can't be a function and a data
     member with the same name, and if there's a function and a type
     with the same name, the type is hidden by the function.  */
  if (!lfi->want_type)
    {
      int idx = lookup_fnfields_here (type, lfi->name);
      if (idx >= 0)
	nval = TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type), idx);
    }

  if (!nval)
    /* Look for a data member or type.  */
    nval = lookup_field_1 (type, lfi->name);

  /* If there is no declaration with the indicated name in this type,
     then there's nothing to do.  */
  if (!nval)
    return NULL_TREE;

  /* If we're looking up a type (as with an elaborated type specifier)
     we ignore all non-types we find.  */
  if (lfi->want_type && TREE_CODE (nval) != TYPE_DECL)
    {
      nval = purpose_member (lfi->name, CLASSTYPE_TAGS (type));
      if (nval)
	nval = TYPE_MAIN_DECL (TREE_VALUE (nval));
      else 
	return NULL_TREE;
    }

  /* You must name a template base class with a template-id.  */
  if (!same_type_p (type, lfi->type) 
      && template_self_reference_p (type, nval))
    return NULL_TREE;

  from_dep_base_p = dependent_base_p (binfo);
  if (lfi->from_dep_base_p && !from_dep_base_p)
    {
      /* If the new declaration is not found via a dependent base, and
	 the old one was, then we must prefer the new one.  We weren't
	 really supposed to be able to find the old one, so we don't
	 want to be affected by a specialization.  Consider:

	   struct B { typedef int I; };
	   template <typename T> struct D1 : virtual public B {}; 
	   template <typename T> struct D :
	   public D1, virtual pubic B { I i; };

	 The `I' in `D<T>' is unambigousuly `B::I', regardless of how
	 D1 is specialized.  */
      lfi->from_dep_base_p = 0;
      lfi->rval = NULL_TREE;
      lfi->rval_binfo = NULL_TREE;
      lfi->ambiguous = NULL_TREE;
      lfi->errstr = 0;
    }
  else if (lfi->rval_binfo && !lfi->from_dep_base_p && from_dep_base_p)
    /* Similarly, if the old declaration was not found via a dependent
       base, and the new one is, ignore the new one.  */
    return NULL_TREE;

  /* If the lookup already found a match, and the new value doesn't
     hide the old one, we might have an ambiguity.  */
  if (lfi->rval_binfo && !hides (binfo, lfi->rval_binfo))
    {
      if (nval == lfi->rval && SHARED_MEMBER_P (nval))
	/* The two things are really the same.  */
	;
      else if (hides (lfi->rval_binfo, binfo))
	/* The previous value hides the new one.  */
	;
      else
	{
	  /* We have a real ambiguity.  We keep a chain of all the
	     candidates.  */
	  if (!lfi->ambiguous && lfi->rval)
	    {
	      /* This is the first time we noticed an ambiguity.  Add
		 what we previously thought was a reasonable candidate
		 to the list.  */
	      lfi->ambiguous = tree_cons (NULL_TREE, lfi->rval, NULL_TREE);
	      TREE_TYPE (lfi->ambiguous) = error_mark_node;
	    }

	  /* Add the new value.  */
	  lfi->ambiguous = tree_cons (NULL_TREE, nval, lfi->ambiguous);
	  TREE_TYPE (lfi->ambiguous) = error_mark_node;
	  lfi->errstr = "request for member `%D' is ambiguous";
	}
    }
  else
    {
      /* If the thing we're looking for is a virtual base class, then
	 we know we've got what we want at this point; there's no way
	 to get an ambiguity.  */
      if (VBASE_NAME_P (lfi->name))
	{
	  lfi->rval = nval;
	  return nval;
	}

      if (from_dep_base_p && TREE_CODE (nval) != TYPE_DECL
	  /* We need to return a member template class so we can
	     define partial specializations.  Is there a better
	     way?  */
	  && !DECL_CLASS_TEMPLATE_P (nval))
	/* The thing we're looking for isn't a type, so the implicit
	   typename extension doesn't apply, so we just pretend we
	   didn't find anything.  */
	return NULL_TREE;

      lfi->rval = nval;
      lfi->from_dep_base_p = from_dep_base_p;
      lfi->rval_binfo = binfo;
    }

  return NULL_TREE;
}

/* Look for a memer named NAME in an inheritance lattice dominated by
   XBASETYPE.  PROTECT is 0 or two, we do not check access.  If it is
   1, we enforce accessibility.  If PROTECT is zero, then, for an
   ambiguous lookup, we return NULL.  If PROTECT is 1, we issue an
   error message.  If PROTECT is 2, we return a TREE_LIST whose
   TREE_TYPE is error_mark_node and whose TREE_VALUEs are the list of
   ambiguous candidates.

   WANT_TYPE is 1 when we should only return TYPE_DECLs, if no
   TYPE_DECL can be found return NULL_TREE.  */

tree
lookup_member (xbasetype, name, protect, want_type)
     register tree xbasetype, name;
     int protect, want_type;
{
  tree rval, rval_binfo = NULL_TREE;
  tree type = NULL_TREE, basetype_path = NULL_TREE;
  struct lookup_field_info lfi;

  /* rval_binfo is the binfo associated with the found member, note,
     this can be set with useful information, even when rval is not
     set, because it must deal with ALL members, not just non-function
     members.  It is used for ambiguity checking and the hidden
     checks.  Whereas rval is only set if a proper (not hidden)
     non-function member is found.  */

  const char *errstr = 0;

  if (xbasetype == current_class_type && TYPE_BEING_DEFINED (xbasetype)
      && IDENTIFIER_CLASS_VALUE (name))
    {
      tree field = IDENTIFIER_CLASS_VALUE (name);
      if (TREE_CODE (field) != FUNCTION_DECL
	  && ! (want_type && TREE_CODE (field) != TYPE_DECL))
	/* We're in the scope of this class, and the value has already
	   been looked up.  Just return the cached value.  */
	return field;
    }

  if (TREE_CODE (xbasetype) == TREE_VEC)
    {
      type = BINFO_TYPE (xbasetype);
      basetype_path = xbasetype;
    }
  else if (IS_AGGR_TYPE_CODE (TREE_CODE (xbasetype)))
    {
      type = xbasetype;
      basetype_path = TYPE_BINFO (type);
      my_friendly_assert (BINFO_INHERITANCE_CHAIN (basetype_path) == NULL_TREE,
			  980827);
    }
  else
    my_friendly_abort (97);

  complete_type (type);

#ifdef GATHER_STATISTICS
  n_calls_lookup_field++;
#endif /* GATHER_STATISTICS */

  bzero ((PTR) &lfi, sizeof (lfi));
  lfi.type = type;
  lfi.name = name;
  lfi.want_type = want_type;
  bfs_walk (basetype_path, &lookup_field_r, &lookup_field_queue_p, &lfi);
  rval = lfi.rval;
  rval_binfo = lfi.rval_binfo;
  if (rval_binfo)
    type = BINFO_TYPE (rval_binfo);
  errstr = lfi.errstr;

  /* If we are not interested in ambiguities, don't report them;
     just return NULL_TREE.  */
  if (!protect && lfi.ambiguous)
    return NULL_TREE;
  
  if (protect == 2) 
    {
      if (lfi.ambiguous)
	return lfi.ambiguous;
      else
	protect = 0;
    }

  /* [class.access]

     In the case of overloaded function names, access control is
     applied to the function selected by overloaded resolution.  */
  if (rval && protect && !is_overloaded_fn (rval)
      && !enforce_access (xbasetype, rval))
    return error_mark_node;

  if (errstr && protect)
    {
      cp_error (errstr, name, type);
      if (lfi.ambiguous)
        print_candidates (lfi.ambiguous);
      rval = error_mark_node;
    }

  /* If the thing we found was found via the implicit typename
     extension, build the typename type.  */
  if (rval && lfi.from_dep_base_p && !DECL_CLASS_TEMPLATE_P (rval))
    rval = TYPE_STUB_DECL (build_typename_type (BINFO_TYPE (basetype_path),
						name, name,
						TREE_TYPE (rval)));

  if (rval && is_overloaded_fn (rval)) 
    {
      rval = tree_cons (basetype_path, rval, NULL_TREE);
      SET_BASELINK_P (rval);
    }

  return rval;
}

/* Like lookup_member, except that if we find a function member we
   return NULL_TREE.  */

tree
lookup_field (xbasetype, name, protect, want_type)
     register tree xbasetype, name;
     int protect, want_type;
{
  tree rval = lookup_member (xbasetype, name, protect, want_type);
  
  /* Ignore functions.  */
  if (rval && TREE_CODE (rval) == TREE_LIST)
    return NULL_TREE;

  return rval;
}

/* Like lookup_member, except that if we find a non-function member we
   return NULL_TREE.  */

tree
lookup_fnfields (xbasetype, name, protect)
     register tree xbasetype, name;
     int protect;
{
  tree rval = lookup_member (xbasetype, name, protect, /*want_type=*/0);

  /* Ignore non-functions.  */
  if (rval && TREE_CODE (rval) != TREE_LIST)
    return NULL_TREE;

  return rval;
}

/* TYPE is a class type. Return the index of the fields within
   the method vector with name NAME, or -1 is no such field exists.  */

int
lookup_fnfields_1 (type, name)
     tree type, name;
{
  tree method_vec 
    = CLASS_TYPE_P (type) ? CLASSTYPE_METHOD_VEC (type) : NULL_TREE;

  if (method_vec != 0)
    {
      register int i;
      register tree *methods = &TREE_VEC_ELT (method_vec, 0);
      int len = TREE_VEC_LENGTH (method_vec);
      tree tmp;

#ifdef GATHER_STATISTICS
      n_calls_lookup_fnfields_1++;
#endif /* GATHER_STATISTICS */

      /* Constructors are first...  */
      if (name == ctor_identifier)
	return methods[0] ? 0 : -1;

      /* and destructors are second.  */
      if (name == dtor_identifier)
	return methods[1] ? 1 : -1;

      for (i = 2; i < len && methods[i]; ++i)
	{
#ifdef GATHER_STATISTICS
	  n_outer_fields_searched++;
#endif /* GATHER_STATISTICS */

	  tmp = OVL_CURRENT (methods[i]);
	  if (DECL_NAME (tmp) == name)
	    return i;

	  /* If the type is complete and we're past the conversion ops,
	     switch to binary search.  */
	  if (! DECL_CONV_FN_P (tmp)
	      && TYPE_SIZE (type))
	    {
	      int lo = i + 1, hi = len;

	      while (lo < hi)
		{
		  i = (lo + hi) / 2;

#ifdef GATHER_STATISTICS
		  n_outer_fields_searched++;
#endif /* GATHER_STATISTICS */

		  tmp = DECL_NAME (OVL_CURRENT (methods[i]));

		  if (tmp > name)
		    hi = i;
		  else if (tmp < name)
		    lo = i + 1;
		  else
		    return i;
		}
	      break;
	    }
	}

      /* If we didn't find it, it might have been a template
	 conversion operator.  (Note that we don't look for this case
	 above so that we will always find specializations first.)  */
      if (IDENTIFIER_TYPENAME_P (name)) 
	{
	  for (i = 2; i < len && methods[i]; ++i)
	    {
	      tmp = OVL_CURRENT (methods[i]);
	      if (! DECL_CONV_FN_P (tmp))
		{
		  /* Since all conversion operators come first, we know
		     there is no such operator.  */
		  break;
		}
	      else if (TREE_CODE (tmp) == TEMPLATE_DECL)
		return i;
	    }
	}
    }

  return -1;
}

/* Walk the class hierarchy dominated by TYPE.  FN is called for each
   type in the hierarchy, in a breadth-first preorder traversal.  .
   If it ever returns a non-NULL value, that value is immediately
   returned and the walk is terminated.  At each node FN, is passed a
   BINFO indicating the path from the curently visited base-class to
   TYPE.  The TREE_CHAINs of the BINFOs may be used for scratch space;
   they are otherwise unused.  Before each base-class is walked QFN is
   called.  If the value returned is non-zero, the base-class is
   walked; otherwise it is not.  If QFN is NULL, it is treated as a
   function which always returns 1.  Both FN and QFN are passed the
   DATA whenever they are called.  */

static tree
bfs_walk (binfo, fn, qfn, data)
     tree binfo;
     tree (*fn) PARAMS ((tree, void *));
     tree (*qfn) PARAMS ((tree, void *));
     void *data;
{
  size_t head;
  size_t tail;
  tree rval = NULL_TREE;
  /* An array of the base classes of BINFO.  These will be built up in
     breadth-first order, except where QFN prunes the search.  */
  varray_type bfs_bases;

  /* Start with enough room for ten base classes.  That will be enough
     for most hierarchies.  */
  VARRAY_TREE_INIT (bfs_bases, 10, "search_stack");

  /* Put the first type into the stack.  */
  VARRAY_TREE (bfs_bases, 0) = binfo;
  tail = 1;

  for (head = 0; head < tail; ++head)
    {
      int i;
      int n_baselinks;
      tree binfos;

      /* Pull the next type out of the queue.  */
      binfo = VARRAY_TREE (bfs_bases, head);

      /* If this is the one we're looking for, we're done.  */
      rval = (*fn) (binfo, data);
      if (rval)
	break;

      /* Queue up the base types.  */
      binfos = BINFO_BASETYPES (binfo);
      n_baselinks = binfos ? TREE_VEC_LENGTH (binfos): 0;
      for (i = 0; i < n_baselinks; i++)
	{
	  tree base_binfo = TREE_VEC_ELT (binfos, i);

	  if (qfn)
	    base_binfo = (*qfn) (base_binfo, data);

	  if (base_binfo)
	    {
	      if (tail == VARRAY_SIZE (bfs_bases))
		VARRAY_GROW (bfs_bases, 2 * VARRAY_SIZE (bfs_bases));
	      VARRAY_TREE (bfs_bases, tail) = base_binfo;
	      ++tail;
	    }
	}
    }

  /* Clean up.  */
  VARRAY_FREE (bfs_bases);

  return rval;
}

/* Exactly like bfs_walk, except that a depth-first traversal is
   performed, and PREFN is called in preorder, while POSTFN is called
   in postorder.  */

tree
dfs_walk_real (binfo, prefn, postfn, qfn, data)
     tree binfo;
     tree (*prefn) PARAMS ((tree, void *));
     tree (*postfn) PARAMS ((tree, void *));
     tree (*qfn) PARAMS ((tree, void *));
     void *data;
{
  int i;
  int n_baselinks;
  tree binfos;
  tree rval = NULL_TREE;

  /* Call the pre-order walking function.  */
  if (prefn)
    {
      rval = (*prefn) (binfo, data);
      if (rval)
	return rval;
    }

  /* Process the basetypes.  */
  binfos = BINFO_BASETYPES (binfo);
  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos): 0;
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      
      if (qfn)
	base_binfo = (*qfn) (base_binfo, data);

      if (base_binfo)
	{
	  rval = dfs_walk_real (base_binfo, prefn, postfn, qfn, data);
	  if (rval)
	    return rval;
	}
    }

  /* Call the post-order walking function.  */
  if (postfn)
    rval = (*postfn) (binfo, data);
  
  return rval;
}

/* Exactly like bfs_walk, except that a depth-first post-order traversal is
   performed.  */

tree
dfs_walk (binfo, fn, qfn, data)
     tree binfo;
     tree (*fn) PARAMS ((tree, void *));
     tree (*qfn) PARAMS ((tree, void *));
     void *data;
{
  return dfs_walk_real (binfo, 0, fn, qfn, data);
}

struct gvnt_info 
{
  /* The name of the function we are looking for.  */
  tree name;
  /* The overloaded functions we have found.  */
  tree fields;
};

/* Called from get_virtuals_named_this via bfs_walk.  */

static tree
get_virtuals_named_this_r (binfo, data)
     tree binfo;
     void *data;
{
  struct gvnt_info *gvnti = (struct gvnt_info *) data;
  tree type = BINFO_TYPE (binfo);
  int idx;

  idx = lookup_fnfields_here (BINFO_TYPE (binfo), gvnti->name);
  if (idx >= 0)
    gvnti->fields
      = tree_cons (binfo, 
		   TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type), idx),
		   gvnti->fields);

  return NULL_TREE;
}

/* Return the virtual functions with the indicated NAME in the type
   indicated by BINFO.  The result is a TREE_LIST whose TREE_PURPOSE
   indicates the base class from which the TREE_VALUE (an OVERLOAD or
   just a FUNCTION_DECL) originated.  */

static tree
get_virtuals_named_this (binfo, name)
     tree binfo;
     tree name;
{
  struct gvnt_info gvnti;
  tree fields;

  gvnti.name = name;
  gvnti.fields = NULL_TREE;

  bfs_walk (binfo, get_virtuals_named_this_r, 0, &gvnti);

  /* Get to the function decls, and return the first virtual function
     with this name, if there is one.  */
  for (fields = gvnti.fields; fields; fields = next_baselink (fields))
    {
      tree fndecl;

      for (fndecl = TREE_VALUE (fields); fndecl; fndecl = OVL_NEXT (fndecl))
	if (DECL_VINDEX (OVL_CURRENT (fndecl)))
	  return fields;
    }
  return NULL_TREE;
}

static tree
get_virtual_destructor (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree type = BINFO_TYPE (binfo);
  if (TYPE_HAS_DESTRUCTOR (type)
      && DECL_VINDEX (TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type), 1)))
    return TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type), 1);
  return 0;
}

static tree
tree_has_any_destructor_p (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree type = BINFO_TYPE (binfo);
  return TYPE_NEEDS_DESTRUCTOR (type) ? binfo : NULL_TREE;
}

/* Returns > 0 if a function with type DRETTYPE overriding a function
   with type BRETTYPE is covariant, as defined in [class.virtual].

   Returns 1 if trivial covariance, 2 if non-trivial (requiring runtime
   adjustment), or -1 if pedantically invalid covariance.  */

static int
covariant_return_p (brettype, drettype)
     tree brettype, drettype;
{
  tree binfo;

  if (TREE_CODE (brettype) == FUNCTION_DECL
      || TREE_CODE (brettype) == THUNK_DECL)
    {
      brettype = TREE_TYPE (TREE_TYPE (brettype));
      drettype = TREE_TYPE (TREE_TYPE (drettype));
    }
  else if (TREE_CODE (brettype) == METHOD_TYPE)
    {
      brettype = TREE_TYPE (brettype);
      drettype = TREE_TYPE (drettype);
    }

  if (same_type_p (brettype, drettype))
    return 0;

  if (! (TREE_CODE (brettype) == TREE_CODE (drettype)
	 && (TREE_CODE (brettype) == POINTER_TYPE
	     || TREE_CODE (brettype) == REFERENCE_TYPE)
	 && TYPE_QUALS (brettype) == TYPE_QUALS (drettype)))
    return 0;

  if (! can_convert (brettype, drettype))
    return 0;

  brettype = TREE_TYPE (brettype);
  drettype = TREE_TYPE (drettype);

  /* If not pedantic, allow any standard pointer conversion.  */
  if (! IS_AGGR_TYPE (drettype) || ! IS_AGGR_TYPE (brettype))
    return -1;

  binfo = get_binfo (brettype, drettype, 1);

  /* If we get an error_mark_node from get_binfo, it already complained,
     so let's just succeed.  */
  if (binfo == error_mark_node)
    return 1;

  if (! BINFO_OFFSET_ZEROP (binfo) || TREE_VIA_VIRTUAL (binfo))
    return 2;
  return 1;
}

/* Check that virtual overrider OVERRIDER is acceptable for base function
   BASEFN. Issue diagnostic, and return zero, if unacceptable.  */

static int
check_final_overrider (overrider, basefn)
     tree overrider, basefn;
{
  tree over_type = TREE_TYPE (overrider);
  tree base_type = TREE_TYPE (basefn);
  tree over_return = TREE_TYPE (over_type);
  tree base_return = TREE_TYPE (base_type);
  tree over_throw = TYPE_RAISES_EXCEPTIONS (over_type);
  tree base_throw = TYPE_RAISES_EXCEPTIONS (base_type);
  int i;
  
  if (same_type_p (base_return, over_return))
    /* OK */;
  else if ((i = covariant_return_p (base_return, over_return)))
    {
      if (i == 2)
	sorry ("adjusting pointers for covariant returns");

      if (pedantic && i == -1)
	{
	  cp_pedwarn_at ("invalid covariant return type for `virtual %#D'", overrider);
	  cp_pedwarn_at ("  overriding `virtual %#D' (must be pointer or reference to class)", basefn);
	}
    }
  else if (IS_AGGR_TYPE_2 (base_return, over_return)
	   && same_or_base_type_p (base_return, over_return))
    {
      cp_error_at ("invalid covariant return type for `virtual %#D'", overrider);
      cp_error_at ("  overriding `virtual %#D' (must use pointer or reference)", basefn);
      return 0;
    }
  else if (IDENTIFIER_ERROR_LOCUS (DECL_ASSEMBLER_NAME (overrider)) == NULL_TREE)
    {
      cp_error_at ("conflicting return type specified for `virtual %#D'", overrider);
      cp_error_at ("  overriding `virtual %#D'", basefn);
      SET_IDENTIFIER_ERROR_LOCUS (DECL_ASSEMBLER_NAME (overrider),
                                  DECL_CONTEXT (overrider));
      return 0;
    }
  
  /* Check throw specifier is subset.  */
  /* XXX At the moment, punt on an overriding artificial function. We
     don't generate its exception specifier, so can't check it properly.  */
  if (! DECL_ARTIFICIAL (overrider)
      && !comp_except_specs (base_throw, over_throw, 0))
    {
      cp_error_at ("looser throw specifier for `virtual %#F'", overrider);
      cp_error_at ("  overriding `virtual %#F'", basefn);
      return 0;
    }
  return 1;
}

/* Given a class type TYPE, and a function decl FNDECL, look for a
   virtual function in TYPE's hierarchy which FNDECL could match as a
   virtual function.  It doesn't matter which one we find.

   DTORP is nonzero if we are looking for a destructor.  Destructors
   need special treatment because they do not match by name.  */

tree
get_matching_virtual (binfo, fndecl, dtorp)
     tree binfo, fndecl;
     int dtorp;
{
  tree tmp = NULL_TREE;

  if (TREE_CODE (fndecl) == TEMPLATE_DECL)
    /* In [temp.mem] we have:

         A specialization of a member function template does not
         override a virtual function from a base class.  */
    return NULL_TREE;

  /* Breadth first search routines start searching basetypes
     of TYPE, so we must perform first ply of search here.  */
  if (dtorp)
    return bfs_walk (binfo, get_virtual_destructor,
		     tree_has_any_destructor_p, 0);
  else
    {
      tree drettype, dtypes, btypes, instptr_type;
      tree baselink, best = NULL_TREE;
      tree declarator = DECL_NAME (fndecl);
      if (IDENTIFIER_VIRTUAL_P (declarator) == 0)
	return NULL_TREE;

      baselink = get_virtuals_named_this (binfo, declarator);
      if (baselink == NULL_TREE)
	return NULL_TREE;

      drettype = TREE_TYPE (TREE_TYPE (fndecl));
      dtypes = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
      if (DECL_STATIC_FUNCTION_P (fndecl))
	instptr_type = NULL_TREE;
      else
	instptr_type = TREE_TYPE (TREE_VALUE (dtypes));

      for (; baselink; baselink = next_baselink (baselink))
	{
	  tree tmps;
	  for (tmps = TREE_VALUE (baselink); tmps; tmps = OVL_NEXT (tmps))
	    {
	      tmp = OVL_CURRENT (tmps);
	      if (! DECL_VINDEX (tmp))
		continue;

	      btypes = TYPE_ARG_TYPES (TREE_TYPE (tmp));
	      if (instptr_type == NULL_TREE)
		{
		  if (compparms (TREE_CHAIN (btypes), dtypes))
		    /* Caller knows to give error in this case.  */
		    return tmp;
		  return NULL_TREE;
		}

	      if (/* The first parameter is the `this' parameter,
		     which has POINTER_TYPE, and we can therefore
		     safely use TYPE_QUALS, rather than
		     CP_TYPE_QUALS.  */
		  (TYPE_QUALS (TREE_TYPE (TREE_VALUE (btypes)))
		   == TYPE_QUALS (instptr_type))
		  && compparms (TREE_CHAIN (btypes), TREE_CHAIN (dtypes)))
		{
	          check_final_overrider (fndecl, tmp);

		  /* FNDECL overrides this function.  We continue to
		     check all the other functions in order to catch
		     errors; it might be that in some other baseclass
		     a virtual function was declared with the same
		     parameter types, but a different return type.  */
		  best = tmp;
		}
	    }
	}

      return best;
    }
}

/* A queue function for dfs_walk that skips any nonprimary virtual
   bases and any already marked bases.  */

tree
dfs_skip_nonprimary_vbases_unmarkedp (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  if (TREE_VIA_VIRTUAL (binfo) && !BINFO_PRIMARY_MARKED_P (binfo))
    /* This is a non-primary virtual base.  SKip it.  */
    return NULL_TREE;

  return unmarkedp (binfo, NULL);
}

/* A queue function for dfs_walk that skips any nonprimary virtual
   bases and any unmarked bases.  */

tree
dfs_skip_nonprimary_vbases_markedp (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  if (TREE_VIA_VIRTUAL (binfo) && !BINFO_PRIMARY_MARKED_P (binfo))
    /* This is a non-primary virtual base.  SKip it.  */
    return NULL_TREE;

  return markedp (binfo, NULL);
}

/* Called via dfs_walk from mark_primary_bases.  */

static tree
dfs_mark_primary_bases (binfo, data)
     tree binfo;
     void *data;
{
  int i;
  tree base_binfo;

  if (!CLASSTYPE_HAS_PRIMARY_BASE_P (BINFO_TYPE (binfo)))
    return NULL_TREE;

  i = CLASSTYPE_VFIELD_PARENT (BINFO_TYPE (binfo));
  base_binfo = BINFO_BASETYPE (binfo, i);

  if (!TREE_VIA_VIRTUAL (base_binfo))
    /* Non-virtual base classes are easy.  */
    BINFO_PRIMARY_MARKED_P (base_binfo) = 1;
  else
    {
      tree shared_binfo;

      shared_binfo 
	= BINFO_FOR_VBASE (BINFO_TYPE (base_binfo), (tree) data);

      /* If this virtual base is not already primary somewhere else in
	 the hiearchy, then we'll be using this copy.  */
      if (!BINFO_VBASE_PRIMARY_P (shared_binfo)
	  && !BINFO_VBASE_MARKED (shared_binfo))
	{
	  BINFO_VBASE_PRIMARY_P (shared_binfo) = 1;
	  BINFO_PRIMARY_MARKED_P (base_binfo) = 1;
	}
    }

  return NULL_TREE;
}

/* Set BINFO_PRIMARY_MARKED_P for all binfos in the hierarchy
   dominated by BINFO that are primary bases.  */

void
mark_primary_bases (type)
     tree type;
{
  tree vbase;

  /* Mark the TYPE_BINFO hierarchy.  We need to mark primary bases in
     pre-order to deal with primary virtual bases.  (The virtual base
     would be skipped if it were not marked as primary, and that
     requires getting to dfs_mark_primary_bases before
     dfs_skip_nonprimary_vbases_unmarkedp has a chance to skip the
     virtual base.)  */
  dfs_walk_real (TYPE_BINFO (type), dfs_mark_primary_bases, NULL,
		 dfs_skip_nonprimary_vbases_unmarkedp, type);

  /* Now go through the virtual base classes.  Any that are not
     already primary will need to be allocated in TYPE, and so we need
     to mark their primary bases.  */
  for (vbase = CLASSTYPE_VBASECLASSES (type); 
       vbase; 
       vbase = TREE_CHAIN (vbase))
    {
      if (BINFO_VBASE_PRIMARY_P (vbase))
	/* This virtual base was already included in the hierarchy, so
	   there's nothing to do here.  */
	continue;

      /* Temporarily pretend that VBASE is primary so that its bases
	 will be walked; this is the real copy of VBASE.  */
      BINFO_PRIMARY_MARKED_P (vbase) = 1;

      /* Now, walk its bases.  */
      dfs_walk (vbase, dfs_mark_primary_bases,
		dfs_skip_nonprimary_vbases_unmarkedp, type);

      /* VBASE wasn't really primary.  */
      BINFO_PRIMARY_MARKED_P (vbase) = 0;
      /* And we don't want to allow it to *become* primary if it is a
	 base of some subsequent base class.  */
      SET_BINFO_VBASE_MARKED (vbase);
    }

  /* Clear the VBASE_MARKED bits we set above.  */
  for (vbase = CLASSTYPE_VBASECLASSES (type); 
       vbase; 
       vbase = TREE_CHAIN (vbase))
    CLEAR_BINFO_VBASE_MARKED (vbase);
}

/* If BINFO is a non-primary virtual baseclass (in the hierarchy
   dominated by TYPE), and no primary copy appears anywhere in the
   hierarchy, return the shared copy.  If a primary copy appears
   elsewhere, return NULL_TREE.  Otherwise, return BINFO itself; it is
   either a non-virtual base or a primary virtual base.  */

static tree
get_shared_vbase_if_not_primary (binfo, data)
     tree binfo;
     void *data;
{
  if (TREE_VIA_VIRTUAL (binfo) && !BINFO_PRIMARY_MARKED_P (binfo))
    {
      tree type = (tree) data;

      if (TREE_CODE (type) == TREE_LIST)
	type = TREE_PURPOSE (type);

      /* This is a non-primary virtual base.  If there is no primary
	 version, get the shared version.  */
      binfo = BINFO_FOR_VBASE (BINFO_TYPE (binfo), type);
      if (BINFO_VBASE_PRIMARY_P (binfo))
	return NULL_TREE;
    }

  return binfo;
}

/* A queue function to use with dfs_walk that prevents travel into any
   nonprimary virtual base, or its baseclasses.  DATA should be the
   type of the complete object, or a TREE_LIST whose TREE_PURPOSE is
   the type of the complete object.  By using this function as a queue
   function, you will walk over exactly those BINFOs that actually
   exist in the complete object, including those for virtual base
   classes.  If you SET_BINFO_MARKED for each binfo you process, you
   are further guaranteed that you will walk into each virtual base
   class exactly once.  */

tree
dfs_unmarked_real_bases_queue_p (binfo, data)
     tree binfo;
     void *data;
{
  binfo = get_shared_vbase_if_not_primary (binfo, data); 
  return binfo ? unmarkedp (binfo, NULL) : NULL_TREE;
}

/* Like dfs_unmarked_real_bases_queue_p but walks only into things
   that are marked, rather than unmarked.  */

tree
dfs_marked_real_bases_queue_p (binfo, data)
     tree binfo;
     void *data;
{
  binfo = get_shared_vbase_if_not_primary (binfo, data); 
  return binfo ? markedp (binfo, NULL) : NULL_TREE;
}

/* Like dfs_unmarked_real_bases_queue_p but walks only into things
   that are not BINFO_VTABLE_PATH_MARKED.  */

tree
dfs_vtable_path_unmarked_real_bases_queue_p (binfo, data)
     tree binfo;
     void *data;
{
  binfo = get_shared_vbase_if_not_primary (binfo, data); 
  return binfo ? unmarked_vtable_pathp (binfo, NULL): NULL_TREE;
}

/* Like dfs_unmarked_real_bases_queue_p but walks only into things
   that are BINFO_VTABLE_PATH_MARKED.  */

tree
dfs_vtable_path_marked_real_bases_queue_p (binfo, data)
     tree binfo;
     void *data;
{
  binfo = get_shared_vbase_if_not_primary (binfo, data); 
  return binfo ? marked_vtable_pathp (binfo, NULL): NULL_TREE;
}

/* A queue function that skips all virtual bases (and their 
   bases).  */

tree
dfs_skip_vbases (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  if (TREE_VIA_VIRTUAL (binfo))
    return NULL_TREE;

  return binfo;
}

/* Called via dfs_walk from dfs_get_pure_virtuals.  */

static tree
dfs_get_pure_virtuals (binfo, data)
     tree binfo;
     void *data;
{
  tree type = (tree) data;

  /* We're not interested in primary base classes; the derived class
     of which they are a primary base will contain the information we
     need.  */
  if (!BINFO_PRIMARY_MARKED_P (binfo))
    {
      tree virtuals;
      
      for (virtuals = skip_rtti_stuff (binfo, 
				       BINFO_TYPE (binfo), 
				       NULL);
	   virtuals;
	   virtuals = TREE_CHAIN (virtuals))
	if (DECL_PURE_VIRTUAL_P (TREE_VALUE (virtuals)))
	  CLASSTYPE_PURE_VIRTUALS (type) 
	    = tree_cons (NULL_TREE, TREE_VALUE (virtuals),
			 CLASSTYPE_PURE_VIRTUALS (type));
    }
  
  SET_BINFO_MARKED (binfo);

  return NULL_TREE;
}

/* Set CLASSTYPE_PURE_VIRTUALS for TYPE.  */

void
get_pure_virtuals (type)
     tree type;
{
  tree vbases;

  /* Clear the CLASSTYPE_PURE_VIRTUALS list; whatever is already there
     is going to be overridden.  */
  CLASSTYPE_PURE_VIRTUALS (type) = NULL_TREE;
  /* Now, run through all the bases which are not primary bases, and
     collect the pure virtual functions.  We look at the vtable in
     each class to determine what pure virtual functions are present.
     (A primary base is not interesting because the derived class of
     which it is a primary base will contain vtable entries for the
     pure virtuals in the base class.  */
  dfs_walk (TYPE_BINFO (type), dfs_get_pure_virtuals, 
	    dfs_unmarked_real_bases_queue_p, type);
  dfs_walk (TYPE_BINFO (type), dfs_unmark, 
	    dfs_marked_real_bases_queue_p, type);

  /* Put the pure virtuals in dfs order.  */
  CLASSTYPE_PURE_VIRTUALS (type) = nreverse (CLASSTYPE_PURE_VIRTUALS (type));

  for (vbases = CLASSTYPE_VBASECLASSES (type); 
       vbases; 
       vbases = TREE_CHAIN (vbases))
    {
      tree virtuals;

      for (virtuals = skip_rtti_stuff (vbases, BINFO_TYPE (vbases), NULL);
	   virtuals;
	   virtuals = TREE_CHAIN (virtuals))
	{
	  tree base_fndecl = TREE_VALUE (virtuals);
	  if (DECL_NEEDS_FINAL_OVERRIDER_P (base_fndecl))
	    cp_error ("`%#D' needs a final overrider", base_fndecl);
	}
    }
}

static tree
next_baselink (baselink)
     tree baselink;
{
  tree tmp = TREE_TYPE (baselink);
  baselink = TREE_CHAIN (baselink);
  while (tmp)
    {
      /* @@ does not yet add previous base types.  */
      baselink = tree_cons (TREE_PURPOSE (tmp), TREE_VALUE (tmp),
			    baselink);
      TREE_TYPE (baselink) = TREE_TYPE (tmp);
      tmp = TREE_CHAIN (tmp);
    }
  return baselink;
}

/* DEPTH-FIRST SEARCH ROUTINES.  */

/* This routine converts a pointer to be a pointer of an immediate
   base class.  The normal convert_pointer_to routine would diagnose
   the conversion as ambiguous, under MI code that has the base class
   as an ambiguous base class.  */

static tree
convert_pointer_to_single_level (to_type, expr)
     tree to_type, expr;
{
  tree derived;
  tree binfo_of_derived;
  int i;

  derived = TREE_TYPE (TREE_TYPE (expr));
  binfo_of_derived = TYPE_BINFO (derived);
  my_friendly_assert (BINFO_INHERITANCE_CHAIN (binfo_of_derived) == NULL_TREE,
		      980827);
  for (i = CLASSTYPE_N_BASECLASSES (derived) - 1; i >= 0; --i)
    {
      tree binfo = BINFO_BASETYPE (binfo_of_derived, i);
      my_friendly_assert (BINFO_INHERITANCE_CHAIN (binfo) == binfo_of_derived,
			  980827);
      if (same_type_p (BINFO_TYPE (binfo), to_type))
	return build_vbase_path (PLUS_EXPR, 
				 build_pointer_type (to_type), 
				 expr, binfo, 1);
    }

  my_friendly_abort (19990607);

  /* NOTREACHED */
  return NULL_TREE;
}

tree 
markedp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return BINFO_MARKED (binfo) ? binfo : NULL_TREE; 
}

tree
unmarkedp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  return !BINFO_MARKED (binfo) ? binfo : NULL_TREE;
}

static tree
marked_vtable_pathp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return BINFO_VTABLE_PATH_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree
unmarked_vtable_pathp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return !BINFO_VTABLE_PATH_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree 
marked_new_vtablep (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  return BINFO_NEW_VTABLE_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree
unmarked_new_vtablep (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return !BINFO_NEW_VTABLE_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree
marked_pushdecls_p (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  return (CLASS_TYPE_P (BINFO_TYPE (binfo))
	  && BINFO_PUSHDECLS_MARKED (binfo)) ? binfo : NULL_TREE; 
}

static tree
unmarked_pushdecls_p (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return (CLASS_TYPE_P (BINFO_TYPE (binfo))
	  && !BINFO_PUSHDECLS_MARKED (binfo)) ? binfo : NULL_TREE;
}

#if 0
static int dfs_search_slot_nonempty_p (binfo) tree binfo;
{ return CLASSTYPE_SEARCH_SLOT (BINFO_TYPE (binfo)) != 0; }

static tree 
dfs_debug_unmarkedp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return (!CLASSTYPE_DEBUG_REQUESTED (BINFO_TYPE (binfo)) 
	  ? binfo : NULL_TREE);
}
#endif

/* The worker functions for `dfs_walk'.  These do not need to
   test anything (vis a vis marking) if they are paired with
   a predicate function (above).  */

#if 0
static void
dfs_mark (binfo) tree binfo;
{ SET_BINFO_MARKED (binfo); }
#endif

tree
dfs_unmark (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  CLEAR_BINFO_MARKED (binfo); 
  return NULL_TREE;
}

/* Clear both BINFO_MARKED and BINFO_VBASE_MARKED.  */

tree
dfs_vbase_unmark (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  CLEAR_BINFO_VBASE_MARKED (binfo);
  return dfs_unmark (binfo, data);
}

/* Clear BINFO_VTABLE_PATH_MARKED.  */

tree
dfs_vtable_path_unmark (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  CLEAR_BINFO_VTABLE_PATH_MARKED (binfo); 
  return NULL_TREE;
}

#if 0
static void
dfs_mark_vtable_path (binfo) tree binfo;
{ SET_BINFO_VTABLE_PATH_MARKED (binfo); }

static void
dfs_mark_new_vtable (binfo) tree binfo;
{ SET_BINFO_NEW_VTABLE_MARKED (binfo); }

static void
dfs_unmark_new_vtable (binfo) tree binfo;
{ CLEAR_BINFO_NEW_VTABLE_MARKED (binfo); }

static void
dfs_clear_search_slot (binfo) tree binfo;
{ CLASSTYPE_SEARCH_SLOT (BINFO_TYPE (binfo)) = 0; }

/* Keep this code around in case we later want to control debug info
   based on whether a type is "used".  Currently, we only suppress debug
   info if we can emit it with the vtable.  jason 1999-11-11) */
static tree
dfs_debug_mark (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree t = BINFO_TYPE (binfo);

  CLASSTYPE_DEBUG_REQUESTED (t) = 1;

  /* If interface info is known, either we've already emitted the debug
     info or we don't need to.  */
  if (CLASSTYPE_INTERFACE_KNOWN (t))
    return NULL_TREE;

  /* If the class has virtual functions, we'll emit the debug info
     with the vtable.  */
  if (TYPE_POLYMORPHIC_P (t))
    return NULL_TREE;

  /* We cannot rely on some alien method to solve our problems,
     so we must write out the debug info ourselves.  */
  TYPE_DECL_SUPPRESS_DEBUG (TYPE_NAME (t)) = 0;
  rest_of_type_compilation (t, toplevel_bindings_p ());

  return NULL_TREE;
}
#endif

struct vbase_info 
{
  tree decl_ptr;
  tree inits;
  tree vbase_types;
};

/*  Attach to the type of the virtual base class, the pointer to the
    virtual base class.  */

static tree
dfs_find_vbases (binfo, data)
     tree binfo;
     void *data;
{
  struct vbase_info *vi = (struct vbase_info *) data;
  tree binfos = BINFO_BASETYPES (binfo);
  int i, n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;

  for (i = n_baselinks-1; i >= 0; i--)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);

      if (TREE_VIA_VIRTUAL (base_binfo)
	  && CLASSTYPE_SEARCH_SLOT (BINFO_TYPE (base_binfo)) == 0)
	{
	  tree vbase = BINFO_TYPE (base_binfo);
	  tree binfo = binfo_member (vbase, vi->vbase_types);

	  CLASSTYPE_SEARCH_SLOT (vbase)
	    = build (PLUS_EXPR, build_pointer_type (vbase),
		     vi->decl_ptr, BINFO_OFFSET (binfo));
	}
    }
  SET_BINFO_VTABLE_PATH_MARKED (binfo);
  SET_BINFO_NEW_VTABLE_MARKED (binfo);

  return NULL_TREE;
}

static tree
dfs_init_vbase_pointers (binfo, data)
     tree binfo;
     void *data;
{
  struct vbase_info *vi = (struct vbase_info *) data;
  tree type = BINFO_TYPE (binfo);
  tree fields;
  tree this_vbase_ptr;

  CLEAR_BINFO_VTABLE_PATH_MARKED (binfo);

  if (BINFO_INHERITANCE_CHAIN (binfo))
    {
      this_vbase_ptr = TREE_CHAIN (BINFO_INHERITANCE_CHAIN (binfo));
      if (TREE_VIA_VIRTUAL (binfo))
	this_vbase_ptr = CLASSTYPE_SEARCH_SLOT (type);
      else
	this_vbase_ptr = convert_pointer_to_single_level (type,
							  this_vbase_ptr); 
      TREE_CHAIN (binfo) = this_vbase_ptr;
    }
  else
    this_vbase_ptr = TREE_CHAIN (binfo);

  /* We're going to iterate through all the pointers to virtual
     base-classes.  They come at the beginning of the class.  */
  fields = TYPE_FIELDS (type);
  if (fields == TYPE_VFIELD (type))
    /* If the first field is the vtbl pointer (as happens in the new
       ABI), skip it.  */
    fields = TREE_CHAIN (fields);

  if (fields == NULL_TREE
      || DECL_NAME (fields) == NULL_TREE
      || ! VBASE_NAME_P (DECL_NAME (fields)))
    return NULL_TREE;

  if (build_pointer_type (type) 
      != TYPE_MAIN_VARIANT (TREE_TYPE (this_vbase_ptr)))
    my_friendly_abort (125);

  while (fields && DECL_NAME (fields) && VBASE_NAME_P (DECL_NAME (fields)))
    {
      tree ref = build (COMPONENT_REF, TREE_TYPE (fields),
			build_indirect_ref (this_vbase_ptr, NULL_PTR), fields);
      tree init = CLASSTYPE_SEARCH_SLOT (TREE_TYPE (TREE_TYPE (fields)));
      vi->inits = tree_cons (binfo_member (TREE_TYPE (TREE_TYPE (fields)),
					   vi->vbase_types),
			     build_modify_expr (ref, NOP_EXPR, init),
			     vi->inits);
      fields = TREE_CHAIN (fields);
    }
  
  return NULL_TREE;
}

/* Sometimes this needs to clear both VTABLE_PATH and NEW_VTABLE.  Other
   times, just NEW_VTABLE, but optimizer should make both with equal
   efficiency (though it does not currently).  */

static tree
dfs_clear_vbase_slots (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree type = BINFO_TYPE (binfo);
  CLASSTYPE_SEARCH_SLOT (type) = 0;
  CLEAR_BINFO_VTABLE_PATH_MARKED (binfo);
  CLEAR_BINFO_NEW_VTABLE_MARKED (binfo);
  return NULL_TREE;
}

tree
init_vbase_pointers (type, decl_ptr)
     tree type;
     tree decl_ptr;
{
  if (TYPE_USES_VIRTUAL_BASECLASSES (type))
    {
      struct vbase_info vi;
      int old_flag = flag_this_is_variable;
      tree binfo = TYPE_BINFO (type);
      flag_this_is_variable = -2;

      /* Find all the virtual base classes, marking them for later
	 initialization.  */
      vi.decl_ptr = decl_ptr;
      vi.vbase_types = CLASSTYPE_VBASECLASSES (type);
      vi.inits = NULL_TREE;

      dfs_walk (binfo, dfs_find_vbases, unmarked_vtable_pathp, &vi);

      /* Build up a list of the initializers.  */
      TREE_CHAIN (binfo) = decl_ptr;
      dfs_walk_real (binfo, 
		     dfs_init_vbase_pointers, 0,
		     marked_vtable_pathp,
		     &vi);

      dfs_walk (binfo, dfs_clear_vbase_slots, marked_new_vtablep, 0);
      flag_this_is_variable = old_flag;
      return vi.inits;
    }
  return 0;
}

/* get the virtual context (the vbase that directly contains the
   DECL_CONTEXT of the FNDECL) that the given FNDECL is declared in,
   or NULL_TREE if there is none.

   FNDECL must come from a virtual table from a virtual base to ensure
   that there is only one possible DECL_CONTEXT.

   We know that if there is more than one place (binfo) the fndecl that the
   declared, they all refer to the same binfo.  See get_class_offset_1 for
   the check that ensures this.  */

static tree
virtual_context (fndecl, t, vbase)
     tree fndecl, t, vbase;
{
  tree path;
  if (get_base_distance (DECL_CONTEXT (fndecl), t, 0, &path) < 0)
    {
      /* DECL_CONTEXT can be ambiguous in t.  */
      if (get_base_distance (DECL_CONTEXT (fndecl), vbase, 0, &path) >= 0)
	{
	  while (path)
	    {
	      /* Not sure if checking path == vbase is necessary here, but just in
		 case it is.  */
	      if (TREE_VIA_VIRTUAL (path) || path == vbase)
		return BINFO_FOR_VBASE (BINFO_TYPE (path), t);
	      path = BINFO_INHERITANCE_CHAIN (path);
	    }
	}
      /* This shouldn't happen, I don't want errors! */
      warning ("recoverable compiler error, fixups for virtual function");
      return vbase;
    }
  while (path)
    {
      if (TREE_VIA_VIRTUAL (path))
	return binfo_member (BINFO_TYPE (path), CLASSTYPE_VBASECLASSES (t));
      path = BINFO_INHERITANCE_CHAIN (path);
    }
  return 0;
}

/* Fixups upcast offsets for one vtable.
   Entries may stay within the VBASE given, or
   they may upcast into a direct base, or
   they may upcast into a different vbase.

   We only need to do fixups in case 2 and 3.  In case 2, we add in
   the virtual base offset to effect an upcast, in case 3, we add in
   the virtual base offset to effect an upcast, then subtract out the
   offset for the other virtual base, to effect a downcast into it.

   This routine mirrors fixup_vtable_deltas in functionality, though
   this one is runtime based, and the other is compile time based.
   Conceivably that routine could be removed entirely, and all fixups
   done at runtime.

   VBASE_OFFSETS is an association list of virtual bases that contains
   offset information for the virtual bases, so the offsets are only
   calculated once.  The offsets are computed by where we think the
   vbase should be (as noted by the CLASSTYPE_SEARCH_SLOT) minus where
   the vbase really is.  */

static void
expand_upcast_fixups (binfo, addr, orig_addr, vbase, vbase_addr, t,
		      vbase_offsets)
     tree binfo, addr, orig_addr, vbase, vbase_addr, t, *vbase_offsets;
{
  tree virtuals;
  tree vc;
  tree delta;
  unsigned HOST_WIDE_INT n;

  while (BINFO_PRIMARY_MARKED_P (binfo))
    {
      binfo = BINFO_INHERITANCE_CHAIN (binfo);
      if (TREE_VIA_VIRTUAL (binfo))
	return;
    }

  delta = purpose_member (vbase, *vbase_offsets);
  if (! delta)
    {
      delta = CLASSTYPE_SEARCH_SLOT (BINFO_TYPE (vbase));
      delta = build (MINUS_EXPR, ptrdiff_type_node, delta, vbase_addr);
      delta = save_expr (delta);
      delta = tree_cons (vbase, delta, *vbase_offsets);
      *vbase_offsets = delta;
    }

  virtuals = skip_rtti_stuff (binfo, BINFO_TYPE (binfo), &n);

  while (virtuals)
    {
      tree current_fndecl = TREE_VALUE (virtuals);

      if (current_fndecl
	  && current_fndecl != abort_fndecl
	  && (vc=virtual_context (current_fndecl, t, vbase)) != vbase)
	{
	  /* This may in fact need a runtime fixup.  */
	  tree idx = build_int_2 (n, 0);
	  tree vtbl = BINFO_VTABLE (binfo);
	  tree nvtbl = lookup_name (DECL_NAME (vtbl), 0);
	  tree aref, ref, naref;
	  tree old_delta, new_delta;
	  tree init;

	  if (nvtbl == NULL_TREE
	      || nvtbl == IDENTIFIER_GLOBAL_VALUE (DECL_NAME (vtbl)))
	    {
	      /* Dup it if it isn't in local scope yet.  */
	      nvtbl = build_decl
		(VAR_DECL, DECL_NAME (vtbl),
		 TYPE_MAIN_VARIANT (TREE_TYPE (vtbl)));
	      DECL_ALIGN (nvtbl) = MAX (TYPE_ALIGN (double_type_node),
					DECL_ALIGN (nvtbl));
	      TREE_READONLY (nvtbl) = 0;
	      DECL_ARTIFICIAL (nvtbl) = 1;
	      nvtbl = pushdecl (nvtbl);
	      init = NULL_TREE;
	      cp_finish_decl (nvtbl, init, NULL_TREE,
			      LOOKUP_ONLYCONVERTING);

	      /* We don't set DECL_VIRTUAL_P and DECL_CONTEXT on nvtbl
		 because they wouldn't be useful; everything that wants to
		 look at the vtable will look at the decl for the normal
		 vtable.  Setting DECL_CONTEXT also screws up
		 decl_function_context.  */

	      init = build (MODIFY_EXPR, TREE_TYPE (nvtbl),
			    nvtbl, vtbl);
	      finish_expr_stmt (init);
	      /* Update the vtable pointers as necessary.  */
	      ref = build_vfield_ref
		(build_indirect_ref (addr, NULL_PTR),
		 DECL_CONTEXT (TYPE_VFIELD (BINFO_TYPE (binfo))));
	      finish_expr_stmt
		(build_modify_expr (ref, NOP_EXPR, nvtbl));
	    }
	  assemble_external (vtbl);
	  aref = build_array_ref (vtbl, idx);
	  naref = build_array_ref (nvtbl, idx);
	  old_delta = build_component_ref (aref, delta_identifier,
					   NULL_TREE, 0);
	  new_delta = build_component_ref (naref, delta_identifier,
					   NULL_TREE, 0);

	  /* This is a upcast, so we have to add the offset for the
	     virtual base.  */
	  old_delta = build_binary_op (PLUS_EXPR, old_delta,
				       TREE_VALUE (delta));
	  if (vc)
	    {
	      /* If this is set, we need to subtract out the delta
		 adjustments for the other virtual base that we
		 downcast into.  */
	      tree vc_delta = purpose_member (vc, *vbase_offsets);
	      if (! vc_delta)
		{
		  tree vc_addr = convert_pointer_to_real (vc, orig_addr);
		  vc_delta = CLASSTYPE_SEARCH_SLOT (BINFO_TYPE (vc));
		  vc_delta = build (MINUS_EXPR, ptrdiff_type_node,
				    vc_delta, vc_addr);
		  vc_delta = save_expr (vc_delta);
		  *vbase_offsets = tree_cons (vc, vc_delta, *vbase_offsets);
		}
	      else
		vc_delta = TREE_VALUE (vc_delta);
   
	      /* This is a downcast, so we have to subtract the offset
		 for the virtual base.  */
	      old_delta = build_binary_op (MINUS_EXPR, old_delta, vc_delta);
	    }

	  TREE_READONLY (new_delta) = 0;
	  TREE_TYPE (new_delta) = 
	    cp_build_qualified_type (TREE_TYPE (new_delta),
				     CP_TYPE_QUALS (TREE_TYPE (new_delta))
				     & ~TYPE_QUAL_CONST);
	  finish_expr_stmt (build_modify_expr (new_delta, NOP_EXPR,
					       old_delta));
	}
      ++n;
      virtuals = TREE_CHAIN (virtuals);
    }
}

/* Fixup upcast offsets for all direct vtables.  Patterned after
   expand_direct_vtbls_init.  */

static void
fixup_virtual_upcast_offsets (real_binfo, binfo, init_self, can_elide, addr, orig_addr, type, vbase, vbase_offsets)
     tree real_binfo, binfo;
     int init_self, can_elide;
     tree addr, orig_addr, type, vbase, *vbase_offsets;
{
  tree real_binfos = BINFO_BASETYPES (real_binfo);
  tree binfos = BINFO_BASETYPES (binfo);
  int i, n_baselinks = real_binfos ? TREE_VEC_LENGTH (real_binfos) : 0;

  for (i = 0; i < n_baselinks; i++)
    {
      tree real_base_binfo = TREE_VEC_ELT (real_binfos, i);
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      int is_not_base_vtable
	= !BINFO_PRIMARY_MARKED_P (real_base_binfo);
      if (! TREE_VIA_VIRTUAL (real_base_binfo))
	fixup_virtual_upcast_offsets (real_base_binfo, base_binfo,
				      is_not_base_vtable, can_elide, addr,
				      orig_addr, type, vbase, vbase_offsets);
    }
#if 0
  /* Before turning this on, make sure it is correct.  */
  if (can_elide && ! BINFO_MODIFIED (binfo))
    return;
#endif
  /* Should we use something besides CLASSTYPE_VFIELDS? */
  if (init_self && CLASSTYPE_VFIELDS (BINFO_TYPE (real_binfo)))
    {
      tree new_addr = convert_pointer_to_real (binfo, addr);
      expand_upcast_fixups (real_binfo, new_addr, orig_addr, vbase, addr,
			    type, vbase_offsets);
    }
}

/* Fixup all the virtual upcast offsets for TYPE.  DECL_PTR is the
   address of the sub-object being initialized.  */

static void
fixup_all_virtual_upcast_offsets (type, decl_ptr)
     tree type;
     tree decl_ptr;
{
  tree if_stmt;
  tree in_charge_node;
  tree vbases;

  /* Only tweak the vtables if we're in charge.  */
  in_charge_node = current_in_charge_parm;
  if (!in_charge_node)
    /* There's no need for any fixups in this case.  */
    return;
  in_charge_node = build_binary_op (EQ_EXPR, 
				    in_charge_node, integer_zero_node);
  if_stmt = begin_if_stmt ();
  finish_if_stmt_cond (in_charge_node, if_stmt);
  
  /* Iterate through the virtual bases, fixing up the upcast offset
     for each one.  */
  for (vbases = CLASSTYPE_VBASECLASSES (type);
       vbases;
       vbases = TREE_CHAIN (vbases))
    {
      if (flag_vtable_thunks)
	/* We don't have dynamic thunks yet!  So for now, just fail
	   silently.  */
	;
      else
	{
	  tree vbase;
	  tree vbase_offsets;
	  tree addr;

	  vbase = find_vbase_instance (BINFO_TYPE (vbases), type);
	  vbase_offsets = NULL_TREE;
	  addr = convert_pointer_to_vbase (BINFO_TYPE (vbases), decl_ptr);
	  fixup_virtual_upcast_offsets (vbase,
					TYPE_BINFO (BINFO_TYPE (vbases)),
					1, 0, addr, decl_ptr,
					type, vbase, &vbase_offsets);
	}
    }

  /* Close out the if-statement.  */
  finish_then_clause (if_stmt);
  finish_if_stmt ();
}

/* Generate the code needed to initialize all the virtual function
   table slots of all the virtual baseclasses.  BINFO is the binfo
   which determines the virtual baseclasses to use.  TRUE_EXP is the
   true object we are initializing, and DECL_PTR is the pointer to the
   sub-object we are initializing.  */

void
expand_indirect_vtbls_init (binfo, decl_ptr)
     tree binfo;
     tree decl_ptr;
{
  tree type = BINFO_TYPE (binfo);

  /* This function executes during the finish_function() segment,
     AFTER the auto variables and temporary stack space has been marked
     unused...If space is needed for the virtual function tables,
     some of them might fit within what the compiler now thinks
     are available stack slots... These values are actually initialized at
     the beginnning of the function, so when the automatics use their space,
     they will overwrite the values that are placed here. Marking all
     temporary space as unavailable prevents this from happening. */

  mark_all_temps_used();

  if (TYPE_USES_VIRTUAL_BASECLASSES (type))
    {
      tree vbases = CLASSTYPE_VBASECLASSES (type);
      struct vbase_info vi;
      vi.decl_ptr = decl_ptr;
      vi.vbase_types = vbases;

      dfs_walk (binfo, dfs_find_vbases, unmarked_new_vtablep, &vi);
      fixup_all_virtual_upcast_offsets (type, vi.decl_ptr);
      dfs_walk (binfo, dfs_clear_vbase_slots, marked_new_vtablep, 0);
    }
}

/* get virtual base class types.
   This adds type to the vbase_types list in reverse dfs order.
   Ordering is very important, so don't change it.  */

static tree
dfs_get_vbase_types (binfo, data)
     tree binfo;
     void *data;
{
  tree type = (tree) data;

  if (TREE_VIA_VIRTUAL (binfo) && ! BINFO_VBASE_MARKED (binfo))
    {
      tree new_vbase = make_binfo (integer_zero_node, 
				   BINFO_TYPE (binfo),
				   BINFO_VTABLE (binfo),
				   BINFO_VIRTUALS (binfo));
      unshare_base_binfos (new_vbase);
      TREE_VIA_VIRTUAL (new_vbase) = 1;
      BINFO_INHERITANCE_CHAIN (new_vbase) = TYPE_BINFO (type);
      TREE_CHAIN (new_vbase) = CLASSTYPE_VBASECLASSES (type);
      CLASSTYPE_VBASECLASSES (type) = new_vbase;
      SET_BINFO_VBASE_MARKED (binfo);
    }
  SET_BINFO_MARKED (binfo);
  return NULL_TREE;
}

/* Set CLASSTYPE_VBASECLASSES for TYPE.  */

void
get_vbase_types (type)
     tree type;
{
  CLASSTYPE_VBASECLASSES (type) = NULL_TREE;
  dfs_walk (TYPE_BINFO (type), dfs_get_vbase_types, unmarkedp, type);
  /* Rely upon the reverse dfs ordering from dfs_get_vbase_types, and now
     reverse it so that we get normal dfs ordering.  */
  CLASSTYPE_VBASECLASSES (type) = nreverse (CLASSTYPE_VBASECLASSES (type));
  dfs_walk (TYPE_BINFO (type), dfs_vbase_unmark, markedp, 0);
}

/* Called from find_vbase_instance via dfs_walk.  */

static tree
dfs_find_vbase_instance (binfo, data)
     tree binfo;
     void *data;
{
  tree base = TREE_VALUE ((tree) data);

  if (BINFO_PRIMARY_MARKED_P (binfo)
      && same_type_p (BINFO_TYPE (binfo), base))
    return binfo;

  return NULL_TREE;
}

/* Find the real occurrence of the virtual BASE (a class type) in the
   hierarchy dominated by TYPE.  */

tree
find_vbase_instance (base, type)
     tree base;
     tree type;
{
  tree instance;

  instance = BINFO_FOR_VBASE (base, type);
  if (!BINFO_VBASE_PRIMARY_P (instance))
    return instance;

  return dfs_walk (TYPE_BINFO (type), 
		   dfs_find_vbase_instance, 
		   NULL,
		   build_tree_list (type, base));
}


/* Debug info for C++ classes can get very large; try to avoid
   emitting it everywhere.

   Note that this optimization wins even when the target supports
   BINCL (if only slightly), and reduces the amount of work for the
   linker.  */

void
maybe_suppress_debug_info (t)
     tree t;
{
  /* We can't do the usual TYPE_DECL_SUPPRESS_DEBUG thing with DWARF, which
     does not support name references between translation units.  It supports
     symbolic references between translation units, but only within a single
     executable or shared library.

     For DWARF 2, we handle TYPE_DECL_SUPPRESS_DEBUG by pretending
     that the type was never defined, so we only get the members we
     actually define.  */
  if (write_symbols == DWARF_DEBUG || write_symbols == NO_DEBUG)
    return;

  /* We might have set this earlier in cp_finish_decl.  */
  TYPE_DECL_SUPPRESS_DEBUG (TYPE_MAIN_DECL (t)) = 0;

  /* If we already know how we're handling this class, handle debug info
     the same way.  */
  if (CLASSTYPE_INTERFACE_ONLY (t))
    TYPE_DECL_SUPPRESS_DEBUG (TYPE_MAIN_DECL (t)) = 1;
  else if (CLASSTYPE_INTERFACE_KNOWN (t))
    /* Don't set it.  */;
  /* If the class has a vtable, write out the debug info along with
     the vtable.  */
  else if (TYPE_CONTAINS_VPTR_P (t))
    TYPE_DECL_SUPPRESS_DEBUG (TYPE_MAIN_DECL (t)) = 1;

  /* Otherwise, just emit the debug info normally.  */
}

#if 0
/* Keep this code around in case we later want to control debug info
   based on whether a type is "used".  Currently, we only suppress debug
   info if we can emit it with the vtable.  jason 1999-11-11) */

/* If we want debug info for a type TYPE, make sure all its base types
   are also marked as being potentially interesting.  This avoids
   the problem of not writing any debug info for intermediate basetypes
   that have abstract virtual functions.  Also mark member types.  */

void
note_debug_info_needed (type)
     tree type;
{
  tree field;

  if (current_template_parms)
    return;
    
  if (TYPE_BEING_DEFINED (type))
    /* We can't go looking for the base types and fields just yet.  */
    return;

  /* See the comment in maybe_suppress_debug_info.  */
  if (write_symbols == DWARF_DEBUG || write_symbols == NO_DEBUG)
    return;

  dfs_walk (TYPE_BINFO (type), dfs_debug_mark, dfs_debug_unmarkedp, 0);
  for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
    {
      tree ttype;
      if (TREE_CODE (field) == FIELD_DECL
	  && IS_AGGR_TYPE (ttype = target_type (TREE_TYPE (field)))
	  && dfs_debug_unmarkedp (TYPE_BINFO (ttype), 0))
	note_debug_info_needed (ttype);
    }
}
#endif

/* Subroutines of push_class_decls ().  */

/* Returns 1 iff BINFO is a base we shouldn't really be able to see into,
   because it (or one of the intermediate bases) depends on template parms.  */

static int
dependent_base_p (binfo)
     tree binfo;
{
  for (; binfo; binfo = BINFO_INHERITANCE_CHAIN (binfo))
    {
      if (currently_open_class (TREE_TYPE (binfo)))
	break;
      if (uses_template_parms (TREE_TYPE (binfo)))
	return 1;
    }
  return 0;
}

static void
setup_class_bindings (name, type_binding_p)
     tree name;
     int type_binding_p;
{
  tree type_binding = NULL_TREE;
  tree value_binding;

  /* If we've already done the lookup for this declaration, we're
     done.  */
  if (IDENTIFIER_CLASS_VALUE (name))
    return;

  /* First, deal with the type binding.  */
  if (type_binding_p)
    {
      type_binding = lookup_member (current_class_type, name,
				    /*protect=*/2,
				    /*want_type=*/1);
      if (TREE_CODE (type_binding) == TREE_LIST 
	  && TREE_TYPE (type_binding) == error_mark_node)
	/* NAME is ambiguous.  */
	push_class_level_binding (name, type_binding);
      else
	pushdecl_class_level (type_binding);
    }

  /* Now, do the value binding.  */
  value_binding = lookup_member (current_class_type, name,
				 /*protect=*/2,
				 /*want_type=*/0);

  if (type_binding_p
      && (TREE_CODE (value_binding) == TYPE_DECL
	  || (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.  */
    my_friendly_assert (type_binding_p, 19990401);
  else if (value_binding)
    {
      if (TREE_CODE (value_binding) == TREE_LIST 
	  && TREE_TYPE (value_binding) == error_mark_node)
	/* NAME is ambiguous.  */
	push_class_level_binding (name, value_binding);
      else
	{
	  if (BASELINK_P (value_binding))
	    /* NAME is some overloaded functions.  */
	    value_binding = TREE_VALUE (value_binding);
	  pushdecl_class_level (value_binding);
	}
    }
}

/* Push class-level declarations for any names appearing in BINFO that
   are TYPE_DECLS.  */

static tree
dfs_push_type_decls (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree type;
  tree fields;

  type = BINFO_TYPE (binfo);
  for (fields = TYPE_FIELDS (type); fields; fields = TREE_CHAIN (fields))
    if (DECL_NAME (fields) && TREE_CODE (fields) == TYPE_DECL
	&& !(!same_type_p (type, current_class_type)
	     && template_self_reference_p (type, fields)))
      setup_class_bindings (DECL_NAME (fields), /*type_binding_p=*/1);

  /* We can't just use BINFO_MARKED because envelope_add_decl uses
     DERIVED_FROM_P, which calls get_base_distance.  */
  SET_BINFO_PUSHDECLS_MARKED (binfo);

  return NULL_TREE;
}

/* Push class-level declarations for any names appearing in BINFO that
   are not TYPE_DECLS.  */

static tree
dfs_push_decls (binfo, data)
     tree binfo;
     void *data;
{
  tree type;
  tree method_vec;
  int dep_base_p;

  type = BINFO_TYPE (binfo);
  dep_base_p = (processing_template_decl && type != current_class_type
		&& dependent_base_p (binfo));
  if (!dep_base_p)
    {
      tree fields;
      for (fields = TYPE_FIELDS (type); fields; fields = TREE_CHAIN (fields))
	if (DECL_NAME (fields) 
	    && TREE_CODE (fields) != TYPE_DECL
	    && TREE_CODE (fields) != USING_DECL)
	  setup_class_bindings (DECL_NAME (fields), /*type_binding_p=*/0);
	else if (TREE_CODE (fields) == FIELD_DECL
		 && ANON_AGGR_TYPE_P (TREE_TYPE (fields)))
	  dfs_push_decls (TYPE_BINFO (TREE_TYPE (fields)), data);
	  
      method_vec = (CLASS_TYPE_P (type) 
		    ? CLASSTYPE_METHOD_VEC (type) : NULL_TREE);
      if (method_vec)
	{
	  tree *methods;
	  tree *end;

	  /* Farm out constructors and destructors.  */
	  end = TREE_VEC_END (method_vec);

	  for (methods = &TREE_VEC_ELT (method_vec, 2);
	       *methods && methods != end;
	       methods++)
	    setup_class_bindings (DECL_NAME (OVL_CURRENT (*methods)), 
				  /*type_binding_p=*/0);
	}
    }

  CLEAR_BINFO_PUSHDECLS_MARKED (binfo);

  return NULL_TREE;
}

/* When entering the scope of a class, we cache all of the
   fields that that class provides within its inheritance
   lattice.  Where ambiguities result, we mark them
   with `error_mark_node' so that if they are encountered
   without explicit qualification, we can emit an error
   message.  */

void
push_class_decls (type)
     tree type;
{
  search_stack = push_search_level (search_stack, &search_obstack);

  /* Enter type declarations and mark.  */
  dfs_walk (TYPE_BINFO (type), dfs_push_type_decls, unmarked_pushdecls_p, 0);

  /* Enter non-type declarations and unmark.  */
  dfs_walk (TYPE_BINFO (type), dfs_push_decls, marked_pushdecls_p, 0);
}

/* Here's a subroutine we need because C lacks lambdas.  */

static tree
dfs_unuse_fields (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree type = TREE_TYPE (binfo);
  tree fields;

  for (fields = TYPE_FIELDS (type); fields; fields = TREE_CHAIN (fields))
    {
      if (TREE_CODE (fields) != FIELD_DECL)
	continue;

      TREE_USED (fields) = 0;
      if (DECL_NAME (fields) == NULL_TREE
	  && ANON_AGGR_TYPE_P (TREE_TYPE (fields)))
	unuse_fields (TREE_TYPE (fields));
    }

  return NULL_TREE;
}

void
unuse_fields (type)
     tree type;
{
  dfs_walk (TYPE_BINFO (type), dfs_unuse_fields, unmarkedp, 0);
}

void
pop_class_decls ()
{
  /* We haven't pushed a search level when dealing with cached classes,
     so we'd better not try to pop it.  */
  if (search_stack)
    search_stack = pop_search_level (search_stack);
}

void
print_search_statistics ()
{
#ifdef GATHER_STATISTICS
  fprintf (stderr, "%d fields searched in %d[%d] calls to lookup_field[_1]\n",
	   n_fields_searched, n_calls_lookup_field, n_calls_lookup_field_1);
  fprintf (stderr, "%d fnfields searched in %d calls to lookup_fnfields\n",
	   n_outer_fields_searched, n_calls_lookup_fnfields);
  fprintf (stderr, "%d calls to get_base_type\n", n_calls_get_base_type);
#else /* GATHER_STATISTICS */
  fprintf (stderr, "no search statistics\n");
#endif /* GATHER_STATISTICS */
}

void
init_search_processing ()
{
  gcc_obstack_init (&search_obstack);
  vptr_identifier = get_identifier ("_vptr");
}

void
reinit_search_statistics ()
{
#ifdef GATHER_STATISTICS
  n_fields_searched = 0;
  n_calls_lookup_field = 0, n_calls_lookup_field_1 = 0;
  n_calls_lookup_fnfields = 0, n_calls_lookup_fnfields_1 = 0;
  n_calls_get_base_type = 0;
  n_outer_fields_searched = 0;
  n_contexts_saved = 0;
#endif /* GATHER_STATISTICS */
}

static tree
add_conversions (binfo, data)
     tree binfo;
     void *data;
{
  int i;
  tree method_vec = CLASSTYPE_METHOD_VEC (BINFO_TYPE (binfo));
  tree *conversions = (tree *) data;

  /* Some builtin types have no method vector, not even an empty one.  */
  if (!method_vec)
    return NULL_TREE;

  for (i = 2; i < TREE_VEC_LENGTH (method_vec); ++i)
    {
      tree tmp = TREE_VEC_ELT (method_vec, i);
      tree name;

      if (!tmp || ! DECL_CONV_FN_P (OVL_CURRENT (tmp)))
	break;

      name = DECL_NAME (OVL_CURRENT (tmp));

      /* Make sure we don't already have this conversion.  */
      if (! IDENTIFIER_MARKED (name))
	{
	  *conversions = tree_cons (binfo, tmp, *conversions);
	  IDENTIFIER_MARKED (name) = 1;
	}
    }
  return NULL_TREE;
}

/* Return a TREE_LIST containing all the non-hidden user-defined
   conversion functions for TYPE (and its base-classes).  The
   TREE_VALUE of each node is a FUNCTION_DECL or an OVERLOAD
   containing the conversion functions.  The TREE_PURPOSE is the BINFO
   from which the conversion functions in this node were selected.  */

tree
lookup_conversions (type)
     tree type;
{
  tree t;
  tree conversions = NULL_TREE;

  if (TYPE_SIZE (type))
    bfs_walk (TYPE_BINFO (type), add_conversions, 0, &conversions);

  for (t = conversions; t; t = TREE_CHAIN (t))
    IDENTIFIER_MARKED (DECL_NAME (OVL_CURRENT (TREE_VALUE (t)))) = 0;

  return conversions;
}

struct overlap_info 
{
  tree compare_type;
  int found_overlap;
};

/* Check whether the empty class indicated by EMPTY_BINFO is also present
   at offset 0 in COMPARE_TYPE, and set found_overlap if so.  */

static tree
dfs_check_overlap (empty_binfo, data)
     tree empty_binfo;
     void *data;
{
  struct overlap_info *oi = (struct overlap_info *) data;
  tree binfo;
  for (binfo = TYPE_BINFO (oi->compare_type); 
       ; 
       binfo = BINFO_BASETYPE (binfo, 0))
    {
      if (BINFO_TYPE (binfo) == BINFO_TYPE (empty_binfo))
	{
	  oi->found_overlap = 1;
	  break;
	}
      else if (BINFO_BASETYPES (binfo) == NULL_TREE)
	break;
    }

  return NULL_TREE;
}

/* Trivial function to stop base traversal when we find something.  */

static tree
dfs_no_overlap_yet (binfo, data)
     tree binfo;
     void *data;
{
  struct overlap_info *oi = (struct overlap_info *) data;
  return !oi->found_overlap ? binfo : NULL_TREE;
}

/* Returns nonzero if EMPTY_TYPE or any of its bases can also be found at
   offset 0 in NEXT_TYPE.  Used in laying out empty base class subobjects.  */

int
types_overlap_p (empty_type, next_type)
     tree empty_type, next_type;
{
  struct overlap_info oi;

  if (! IS_AGGR_TYPE (next_type))
    return 0;
  oi.compare_type = next_type;
  oi.found_overlap = 0;
  dfs_walk (TYPE_BINFO (empty_type), dfs_check_overlap,
	    dfs_no_overlap_yet, &oi);
  return oi.found_overlap;
}

/* Given a vtable VAR, determine which binfo it comes from.

   FIXME What about secondary vtables?  */

tree
binfo_for_vtable (var)
     tree var;
{
  tree binfo = TYPE_BINFO (DECL_CONTEXT (var));
  tree binfos;
  int i;

  while (1)
    {
      binfos = BINFO_BASETYPES (binfo);
      if (binfos == NULL_TREE)
	break;

      i = CLASSTYPE_VFIELD_PARENT (BINFO_TYPE (binfo));
      if (i == -1)
	break;

      binfo = TREE_VEC_ELT (binfos, i);
    }

  return binfo;
}

/* Returns 1 iff BINFO is from a direct or indirect virtual base.  */

int
binfo_from_vbase (binfo)
     tree binfo;
{
  for (; binfo; binfo = BINFO_INHERITANCE_CHAIN (binfo))
    {
      if (TREE_VIA_VIRTUAL (binfo))
	return 1;
    }
  return 0;
}