comment typo

[official-gcc.git] / gcc / cp / tree.c

/* Language-dependent node constructors for parse phase of GNU compiler.
   Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007
   Free Software Foundation, Inc.
   Hacked by Michael Tiemann (tiemann@cygnus.com)

This file is part of GCC.

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

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

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

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "cp-tree.h"
#include "flags.h"
#include "real.h"
#include "rtl.h"
#include "toplev.h"
#include "insn-config.h"
#include "integrate.h"
#include "tree-inline.h"
#include "debug.h"
#include "target.h"
#include "convert.h"

static tree bot_manip (tree *, int *, void *);
static tree bot_replace (tree *, int *, void *);
static tree build_cplus_array_type_1 (tree, tree);
static int list_hash_eq (const void *, const void *);
static hashval_t list_hash_pieces (tree, tree, tree);
static hashval_t list_hash (const void *);
static cp_lvalue_kind lvalue_p_1 (const_tree, int);
static tree build_target_expr (tree, tree);
static tree count_trees_r (tree *, int *, void *);
static tree verify_stmt_tree_r (tree *, int *, void *);
static tree build_local_temp (tree);

static tree handle_java_interface_attribute (tree *, tree, tree, int, bool *);
static tree handle_com_interface_attribute (tree *, tree, tree, int, bool *);
static tree handle_init_priority_attribute (tree *, tree, tree, int, bool *);

/* If REF is an lvalue, returns the kind of lvalue that REF is.
   Otherwise, returns clk_none.  If TREAT_CLASS_RVALUES_AS_LVALUES is
   nonzero, rvalues of class type are considered lvalues.  */

static cp_lvalue_kind
lvalue_p_1 (const_tree ref,
            int treat_class_rvalues_as_lvalues)
{
  cp_lvalue_kind op1_lvalue_kind = clk_none;
  cp_lvalue_kind op2_lvalue_kind = clk_none;

  /* Expressions of reference type are sometimes wrapped in
     INDIRECT_REFs.  INDIRECT_REFs are just internal compiler
     representation, not part of the language, so we have to look
     through them.  */
  if (TREE_CODE (ref) == INDIRECT_REF
      && TREE_CODE (TREE_TYPE (TREE_OPERAND (ref, 0)))
          == REFERENCE_TYPE)
    return lvalue_p_1 (TREE_OPERAND (ref, 0),
                       treat_class_rvalues_as_lvalues);

  if (TREE_CODE (TREE_TYPE (ref)) == REFERENCE_TYPE)
    {
      /* unnamed rvalue references are rvalues */
      if (TYPE_REF_IS_RVALUE (TREE_TYPE (ref))
          && TREE_CODE (ref) != PARM_DECL
          && TREE_CODE (ref) != VAR_DECL
          && TREE_CODE (ref) != COMPONENT_REF)
        return clk_none;

      /* lvalue references and named rvalue references are lvalues.  */
      return clk_ordinary;
    }

  if (ref == current_class_ptr)
    return clk_none;

  switch (TREE_CODE (ref))
    {
    case SAVE_EXPR:
      return clk_none;
      /* preincrements and predecrements are valid lvals, provided
         what they refer to are valid lvals.  */
    case PREINCREMENT_EXPR:
    case PREDECREMENT_EXPR:
    case TRY_CATCH_EXPR:
    case WITH_CLEANUP_EXPR:
    case REALPART_EXPR:
    case IMAGPART_EXPR:
      return lvalue_p_1 (TREE_OPERAND (ref, 0),
                         treat_class_rvalues_as_lvalues);

    case COMPONENT_REF:
      op1_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 0),
                                    treat_class_rvalues_as_lvalues);
      /* Look at the member designator.  */
      if (!op1_lvalue_kind
          /* The "field" can be a FUNCTION_DECL or an OVERLOAD in some
             situations.  */
          || TREE_CODE (TREE_OPERAND (ref, 1)) != FIELD_DECL)
        ;
      else if (DECL_C_BIT_FIELD (TREE_OPERAND (ref, 1)))
        {
          /* Clear the ordinary bit.  If this object was a class
             rvalue we want to preserve that information.  */
          op1_lvalue_kind &= ~clk_ordinary;
          /* The lvalue is for a bitfield.  */
          op1_lvalue_kind |= clk_bitfield;
        }
      else if (DECL_PACKED (TREE_OPERAND (ref, 1)))
        op1_lvalue_kind |= clk_packed;

      return op1_lvalue_kind;

    case STRING_CST:
      return clk_ordinary;

    case CONST_DECL:
    case VAR_DECL:
      if (TREE_READONLY (ref) && ! TREE_STATIC (ref)
          && DECL_LANG_SPECIFIC (ref)
          && DECL_IN_AGGR_P (ref))
        return clk_none;
    case INDIRECT_REF:
    case ARRAY_REF:
    case PARM_DECL:
    case RESULT_DECL:
      if (TREE_CODE (TREE_TYPE (ref)) != METHOD_TYPE)
        return clk_ordinary;
      break;

      /* A currently unresolved scope ref.  */
    case SCOPE_REF:
      gcc_unreachable ();
    case MAX_EXPR:
    case MIN_EXPR:
      /* Disallow <? and >? as lvalues if either argument side-effects.  */
      if (TREE_SIDE_EFFECTS (TREE_OPERAND (ref, 0))
          || TREE_SIDE_EFFECTS (TREE_OPERAND (ref, 1)))
        return clk_none;
      op1_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 0),
                                    treat_class_rvalues_as_lvalues);
      op2_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 1),
                                    treat_class_rvalues_as_lvalues);
      break;

    case COND_EXPR:
      op1_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 1),
                                    treat_class_rvalues_as_lvalues);
      op2_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 2),
                                    treat_class_rvalues_as_lvalues);
      break;

    case MODIFY_EXPR:
      return clk_ordinary;

    case COMPOUND_EXPR:
      return lvalue_p_1 (TREE_OPERAND (ref, 1),
                         treat_class_rvalues_as_lvalues);

    case TARGET_EXPR:
      return treat_class_rvalues_as_lvalues ? clk_class : clk_none;

    case VA_ARG_EXPR:
      return (treat_class_rvalues_as_lvalues
              && CLASS_TYPE_P (TREE_TYPE (ref))
              ? clk_class : clk_none);

    case CALL_EXPR:
      /* Any class-valued call would be wrapped in a TARGET_EXPR.  */
      return clk_none;

    case FUNCTION_DECL:
      /* All functions (except non-static-member functions) are
         lvalues.  */
      return (DECL_NONSTATIC_MEMBER_FUNCTION_P (ref)
              ? clk_none : clk_ordinary);

    case NON_DEPENDENT_EXPR:
      /* We must consider NON_DEPENDENT_EXPRs to be lvalues so that
         things like "&E" where "E" is an expression with a
         non-dependent type work. It is safe to be lenient because an
         error will be issued when the template is instantiated if "E"
         is not an lvalue.  */
      return clk_ordinary;

    default:
      break;
    }

  /* If one operand is not an lvalue at all, then this expression is
     not an lvalue.  */
  if (!op1_lvalue_kind || !op2_lvalue_kind)
    return clk_none;

  /* Otherwise, it's an lvalue, and it has all the odd properties
     contributed by either operand.  */
  op1_lvalue_kind = op1_lvalue_kind | op2_lvalue_kind;
  /* It's not an ordinary lvalue if it involves either a bit-field or
     a class rvalue.  */
  if ((op1_lvalue_kind & ~clk_ordinary) != clk_none)
    op1_lvalue_kind &= ~clk_ordinary;
  return op1_lvalue_kind;
}

/* Returns the kind of lvalue that REF is, in the sense of
   [basic.lval].  This function should really be named lvalue_p; it
   computes the C++ definition of lvalue.  */

cp_lvalue_kind
real_lvalue_p (const_tree ref)
{
  return lvalue_p_1 (ref,
                     /*treat_class_rvalues_as_lvalues=*/0);
}

/* This differs from real_lvalue_p in that class rvalues are
   considered lvalues.  */

int
lvalue_p (const_tree ref)
{
  return
    (lvalue_p_1 (ref, /*class rvalue ok*/ 1) != clk_none);
}

/* Test whether DECL is a builtin that may appear in a
   constant-expression. */

bool
builtin_valid_in_constant_expr_p (const_tree decl)
{
  /* At present BUILT_IN_CONSTANT_P is the only builtin we're allowing
     in constant-expressions.  We may want to add other builtins later. */
  return DECL_IS_BUILTIN_CONSTANT_P (decl);
}

/* Build a TARGET_EXPR, initializing the DECL with the VALUE.  */

static tree
build_target_expr (tree decl, tree value)
{
  tree t;

  t = build4 (TARGET_EXPR, TREE_TYPE (decl), decl, value,
              cxx_maybe_build_cleanup (decl), NULL_TREE);
  /* We always set TREE_SIDE_EFFECTS so that expand_expr does not
     ignore the TARGET_EXPR.  If there really turn out to be no
     side-effects, then the optimizer should be able to get rid of
     whatever code is generated anyhow.  */
  TREE_SIDE_EFFECTS (t) = 1;

  return t;
}

/* Return an undeclared local temporary of type TYPE for use in building a
   TARGET_EXPR.  */

static tree
build_local_temp (tree type)
{
  tree slot = build_decl (VAR_DECL, NULL_TREE, type);
  DECL_ARTIFICIAL (slot) = 1;
  DECL_IGNORED_P (slot) = 1;
  DECL_CONTEXT (slot) = current_function_decl;
  layout_decl (slot, 0);
  return slot;
}

/* Set various status flags when building an AGGR_INIT_EXPR object T.  */

static void
process_aggr_init_operands (tree t)
{
  bool side_effects;

  side_effects = TREE_SIDE_EFFECTS (t);
  if (!side_effects)
    {
      int i, n;
      n = TREE_OPERAND_LENGTH (t);
      for (i = 1; i < n; i++)
        {
          tree op = TREE_OPERAND (t, i);
          if (op && TREE_SIDE_EFFECTS (op))
            {
              side_effects = 1;
              break;
            }
        }
    }
  TREE_SIDE_EFFECTS (t) = side_effects;
}

/* Build an AGGR_INIT_EXPR of class tcc_vl_exp with the indicated RETURN_TYPE,
   FN, and SLOT.  NARGS is the number of call arguments which are specified
   as a tree array ARGS.  */

static tree
build_aggr_init_array (tree return_type, tree fn, tree slot, int nargs,
                       tree *args)
{
  tree t;
  int i;

  t = build_vl_exp (AGGR_INIT_EXPR, nargs + 3);
  TREE_TYPE (t) = return_type;
  AGGR_INIT_EXPR_FN (t) = fn;
  AGGR_INIT_EXPR_SLOT (t) = slot;
  for (i = 0; i < nargs; i++)
    AGGR_INIT_EXPR_ARG (t, i) = args[i];
  process_aggr_init_operands (t);
  return t;
}

/* INIT is a CALL_EXPR or AGGR_INIT_EXPR which needs info about its
   target.  TYPE is the type that this initialization should appear to
   have.

   Build an encapsulation of the initialization to perform
   and return it so that it can be processed by language-independent
   and language-specific expression expanders.  */

tree
build_cplus_new (tree type, tree init)
{
  tree fn;
  tree slot;
  tree rval;
  int is_ctor;

  /* Make sure that we're not trying to create an instance of an
     abstract class.  */
  abstract_virtuals_error (NULL_TREE, type);

  if (TREE_CODE (init) == CALL_EXPR)
    fn = CALL_EXPR_FN (init);
  else if (TREE_CODE (init) == AGGR_INIT_EXPR)
    fn = AGGR_INIT_EXPR_FN (init);
  else
    return convert (type, init);

  is_ctor = (TREE_CODE (fn) == ADDR_EXPR
             && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL
             && DECL_CONSTRUCTOR_P (TREE_OPERAND (fn, 0)));

  slot = build_local_temp (type);

  /* We split the CALL_EXPR into its function and its arguments here.
     Then, in expand_expr, we put them back together.  The reason for
     this is that this expression might be a default argument
     expression.  In that case, we need a new temporary every time the
     expression is used.  That's what break_out_target_exprs does; it
     replaces every AGGR_INIT_EXPR with a copy that uses a fresh
     temporary slot.  Then, expand_expr builds up a call-expression
     using the new slot.  */

  /* If we don't need to use a constructor to create an object of this
     type, don't mess with AGGR_INIT_EXPR.  */
  if (is_ctor || TREE_ADDRESSABLE (type))
    {
      if (TREE_CODE(init) == CALL_EXPR)
        rval = build_aggr_init_array (void_type_node, fn, slot,
                                      call_expr_nargs (init),
                                      CALL_EXPR_ARGP (init));
      else
        rval = build_aggr_init_array (void_type_node, fn, slot,
                                      aggr_init_expr_nargs (init),
                                      AGGR_INIT_EXPR_ARGP (init));
      TREE_SIDE_EFFECTS (rval) = 1;
      AGGR_INIT_VIA_CTOR_P (rval) = is_ctor;
    }
  else
    rval = init;

  rval = build_target_expr (slot, rval);
  TARGET_EXPR_IMPLICIT_P (rval) = 1;

  return rval;
}

/* Build a TARGET_EXPR using INIT to initialize a new temporary of the
   indicated TYPE.  */

tree
build_target_expr_with_type (tree init, tree type)
{
  gcc_assert (!VOID_TYPE_P (type));

  if (TREE_CODE (init) == TARGET_EXPR)
    return init;
  else if (CLASS_TYPE_P (type) && !TYPE_HAS_TRIVIAL_INIT_REF (type)
           && TREE_CODE (init) != COND_EXPR
           && TREE_CODE (init) != CONSTRUCTOR
           && TREE_CODE (init) != VA_ARG_EXPR)
    /* We need to build up a copy constructor call.  COND_EXPR is a special
       case because we already have copies on the arms and we don't want
       another one here.  A CONSTRUCTOR is aggregate initialization, which
       is handled separately.  A VA_ARG_EXPR is magic creation of an
       aggregate; there's no additional work to be done.  */
    return force_rvalue (init);

  return force_target_expr (type, init);
}

/* Like the above function, but without the checking.  This function should
   only be used by code which is deliberately trying to subvert the type
   system, such as call_builtin_trap.  */

tree
force_target_expr (tree type, tree init)
{
  tree slot;

  gcc_assert (!VOID_TYPE_P (type));

  slot = build_local_temp (type);
  return build_target_expr (slot, init);
}

/* Like build_target_expr_with_type, but use the type of INIT.  */

tree
get_target_expr (tree init)
{
  return build_target_expr_with_type (init, TREE_TYPE (init));
}

/* If EXPR is a bitfield reference, convert it to the declared type of
   the bitfield, and return the resulting expression.  Otherwise,
   return EXPR itself.  */

tree
convert_bitfield_to_declared_type (tree expr)
{
  tree bitfield_type;

  bitfield_type = is_bitfield_expr_with_lowered_type (expr);
  if (bitfield_type)
    expr = convert_to_integer (TYPE_MAIN_VARIANT (bitfield_type),
                               expr);
  return expr;
}

/* EXPR is being used in an rvalue context.  Return a version of EXPR
   that is marked as an rvalue.  */

tree
rvalue (tree expr)
{
  tree type;

  if (error_operand_p (expr))
    return expr;

  /* [basic.lval]

     Non-class rvalues always have cv-unqualified types.  */
  type = TREE_TYPE (expr);
  if (!CLASS_TYPE_P (type) && cp_type_quals (type))
    type = TYPE_MAIN_VARIANT (type);

  if (!processing_template_decl && real_lvalue_p (expr))
    expr = build1 (NON_LVALUE_EXPR, type, expr);
  else if (type != TREE_TYPE (expr))
    expr = build_nop (type, expr);

  return expr;
}

\f
/* Hash an ARRAY_TYPE.  K is really of type `tree'.  */

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

  hash = (htab_hash_pointer (TREE_TYPE (t))
          ^ htab_hash_pointer (TYPE_DOMAIN (t)));

  return hash;
}

typedef struct cplus_array_info {
  tree type;
  tree domain;
} cplus_array_info;

/* Compare two ARRAY_TYPEs.  K1 is really of type `tree', K2 is really
   of type `cplus_array_info*'. */

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

  return (TREE_TYPE (t1) == t2->type && TYPE_DOMAIN (t1) == t2->domain);
}

/* Hash table containing all of the C++ array types, including
   dependent array types and array types whose element type is
   cv-qualified.  */
static GTY ((param_is (union tree_node))) htab_t cplus_array_htab;


static tree
build_cplus_array_type_1 (tree elt_type, tree index_type)
{
  tree t;

  if (elt_type == error_mark_node || index_type == error_mark_node)
    return error_mark_node;

  if (dependent_type_p (elt_type)
      || (index_type
          && value_dependent_expression_p (TYPE_MAX_VALUE (index_type))))
    {
      void **e;
      cplus_array_info cai;
      hashval_t hash;

      if (cplus_array_htab == NULL)
        cplus_array_htab = htab_create_ggc (61, &cplus_array_hash,
                                            &cplus_array_compare, NULL);
      
      hash = (htab_hash_pointer (elt_type)
              ^ htab_hash_pointer (index_type));
      cai.type = elt_type;
      cai.domain = index_type;

      e = htab_find_slot_with_hash (cplus_array_htab, &cai, hash, INSERT); 
      if (*e)
        /* We have found the type: we're done.  */
        return (tree) *e;
      else
        {
          /* Build a new array type.  */
          t = make_node (ARRAY_TYPE);
          TREE_TYPE (t) = elt_type;
          TYPE_DOMAIN (t) = index_type;

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

          /* Set the canonical type for this new node.  */
          if (TYPE_STRUCTURAL_EQUALITY_P (elt_type)
              || (index_type && TYPE_STRUCTURAL_EQUALITY_P (index_type)))
            SET_TYPE_STRUCTURAL_EQUALITY (t);
          else if (TYPE_CANONICAL (elt_type) != elt_type
                   || (index_type 
                       && TYPE_CANONICAL (index_type) != index_type))
            TYPE_CANONICAL (t)
                = build_cplus_array_type 
                   (TYPE_CANONICAL (elt_type),
                    index_type? TYPE_CANONICAL (index_type) : index_type);
          else
            TYPE_CANONICAL (t) = t;
        }
    }
  else
    t = build_array_type (elt_type, index_type);

  /* Push these needs up so that initialization takes place
     more easily.  */
  TYPE_NEEDS_CONSTRUCTING (t)
    = TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (elt_type));
  TYPE_HAS_NONTRIVIAL_DESTRUCTOR (t)
    = TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TYPE_MAIN_VARIANT (elt_type));
  return t;
}

tree
build_cplus_array_type (tree elt_type, tree index_type)
{
  tree t;
  int type_quals = cp_type_quals (elt_type);

  if (type_quals != TYPE_UNQUALIFIED)
    elt_type = cp_build_qualified_type (elt_type, TYPE_UNQUALIFIED);

  t = build_cplus_array_type_1 (elt_type, index_type);

  if (type_quals != TYPE_UNQUALIFIED)
    t = cp_build_qualified_type (t, type_quals);

  return t;
}

/* Return a reference type node referring to TO_TYPE.  If RVAL is
   true, return an rvalue reference type, otherwise return an lvalue
   reference type.  If a type node exists, reuse it, otherwise create
   a new one.  */
tree
cp_build_reference_type (tree to_type, bool rval)
{
  tree lvalue_ref, t;
  lvalue_ref = build_reference_type (to_type);
  if (!rval)
    return lvalue_ref;

  /* This code to create rvalue reference types is based on and tied
     to the code creating lvalue reference types in the middle-end
     functions build_reference_type_for_mode and build_reference_type.

     It works by putting the rvalue reference type nodes after the
     lvalue reference nodes in the TYPE_NEXT_REF_TO linked list, so
     they will effectively be ignored by the middle end.  */

  for (t = lvalue_ref; (t = TYPE_NEXT_REF_TO (t)); )
    if (TYPE_REF_IS_RVALUE (t))
      return t;

  t = copy_node (lvalue_ref);

  TYPE_REF_IS_RVALUE (t) = true;
  TYPE_NEXT_REF_TO (t) = TYPE_NEXT_REF_TO (lvalue_ref);
  TYPE_NEXT_REF_TO (lvalue_ref) = t;
  TYPE_MAIN_VARIANT (t) = t;

  if (TYPE_STRUCTURAL_EQUALITY_P (to_type))
    SET_TYPE_STRUCTURAL_EQUALITY (t);
  else if (TYPE_CANONICAL (to_type) != to_type)
    TYPE_CANONICAL (t) 
      = cp_build_reference_type (TYPE_CANONICAL (to_type), rval);
  else
    TYPE_CANONICAL (t) = t;

  layout_type (t);

  return t;

}


\f
/* Make a variant of TYPE, qualified with the TYPE_QUALS.  Handles
   arrays correctly.  In particular, if TYPE is an array of T's, and
   TYPE_QUALS is non-empty, returns an array of qualified T's.

   FLAGS determines how to deal with illformed qualifications. If
   tf_ignore_bad_quals is set, then bad qualifications are dropped
   (this is permitted if TYPE was introduced via a typedef or template
   type parameter). If bad qualifications are dropped and tf_warning
   is set, then a warning is issued for non-const qualifications.  If
   tf_ignore_bad_quals is not set and tf_error is not set, we
   return error_mark_node. Otherwise, we issue an error, and ignore
   the qualifications.

   Qualification of a reference type is valid when the reference came
   via a typedef or template type argument. [dcl.ref] No such
   dispensation is provided for qualifying a function type.  [dcl.fct]
   DR 295 queries this and the proposed resolution brings it into line
   with qualifying a reference.  We implement the DR.  We also behave
   in a similar manner for restricting non-pointer types.  */

tree
cp_build_qualified_type_real (tree type,
                              int type_quals,
                              tsubst_flags_t complain)
{
  tree result;
  int bad_quals = TYPE_UNQUALIFIED;

  if (type == error_mark_node)
    return type;

  if (type_quals == cp_type_quals (type))
    return type;

  if (TREE_CODE (type) == ARRAY_TYPE)
    {
      /* In C++, the qualification really applies to the array element
         type.  Obtain the appropriately qualified element type.  */
      tree t;
      tree element_type
        = cp_build_qualified_type_real (TREE_TYPE (type),
                                        type_quals,
                                        complain);

      if (element_type == error_mark_node)
        return error_mark_node;

      /* See if we already have an identically qualified type.  */
      for (t = TYPE_MAIN_VARIANT (type); t; t = TYPE_NEXT_VARIANT (t))
        if (cp_type_quals (t) == type_quals
            && TYPE_NAME (t) == TYPE_NAME (type)
            && TYPE_CONTEXT (t) == TYPE_CONTEXT (type))
          break;

      if (!t)
        {
          tree index_type = TYPE_DOMAIN (type);
          void **e;
          cplus_array_info cai;
          hashval_t hash;

          if (cplus_array_htab == NULL)
            cplus_array_htab = htab_create_ggc (61, &cplus_array_hash,
                                                &cplus_array_compare, 
                                                NULL);

          hash = (htab_hash_pointer (element_type)
                  ^ htab_hash_pointer (index_type));
          cai.type = element_type;
          cai.domain = index_type;
          
          e = htab_find_slot_with_hash (cplus_array_htab, &cai, hash, INSERT);
          if (*e)
            /* We have found the type: we're done. */
            return (tree) *e;

          /* Build a new array type and add it into the table.  */
          t = build_variant_type_copy (type);
          TREE_TYPE (t) = element_type;
          *e = t;

          /* Set the canonical type for this new node.  */
          if (TYPE_STRUCTURAL_EQUALITY_P (element_type)
              || (index_type && TYPE_STRUCTURAL_EQUALITY_P (index_type)))
            SET_TYPE_STRUCTURAL_EQUALITY (t);
          else if (TYPE_CANONICAL (element_type) != element_type
                   || (index_type 
                       && TYPE_CANONICAL (index_type) != index_type)
                   || TYPE_CANONICAL (type) != type)
            TYPE_CANONICAL (t)
              = build_cplus_array_type
                 (TYPE_CANONICAL (element_type),
                  index_type? TYPE_CANONICAL (index_type) : index_type);
          else
            TYPE_CANONICAL (t) = t;
        }

      /* Even if we already had this variant, we update
         TYPE_NEEDS_CONSTRUCTING and TYPE_HAS_NONTRIVIAL_DESTRUCTOR in case
         they changed since the variant was originally created.

         This seems hokey; if there is some way to use a previous
         variant *without* coming through here,
         TYPE_NEEDS_CONSTRUCTING will never be updated.  */
      TYPE_NEEDS_CONSTRUCTING (t)
        = TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (element_type));
      TYPE_HAS_NONTRIVIAL_DESTRUCTOR (t)
        = TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TYPE_MAIN_VARIANT (element_type));
      return t;
    }
  else if (TYPE_PTRMEMFUNC_P (type))
    {
      /* For a pointer-to-member type, we can't just return a
         cv-qualified version of the RECORD_TYPE.  If we do, we
         haven't changed the field that contains the actual pointer to
         a method, and so TYPE_PTRMEMFUNC_FN_TYPE will be wrong.  */
      tree t;

      t = TYPE_PTRMEMFUNC_FN_TYPE (type);
      t = cp_build_qualified_type_real (t, type_quals, complain);
      return build_ptrmemfunc_type (t);
    }
  else if (TREE_CODE (type) == TYPE_PACK_EXPANSION)
    {
      tree t = PACK_EXPANSION_PATTERN (type);

      t = cp_build_qualified_type_real (t, type_quals, complain);
      return make_pack_expansion (t);
    }

  /* A reference or method type shall not be cv qualified.
     [dcl.ref], [dct.fct]  */
  if (type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE)
      && (TREE_CODE (type) == REFERENCE_TYPE
          || TREE_CODE (type) == METHOD_TYPE))
    {
      bad_quals |= type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
      type_quals &= ~(TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
    }

  /* A restrict-qualified type must be a pointer (or reference)
     to object or incomplete type, or a function type. */
  if ((type_quals & TYPE_QUAL_RESTRICT)
      && TREE_CODE (type) != TEMPLATE_TYPE_PARM
      && TREE_CODE (type) != TYPENAME_TYPE
      && TREE_CODE (type) != FUNCTION_TYPE
      && !POINTER_TYPE_P (type))
    {
      bad_quals |= TYPE_QUAL_RESTRICT;
      type_quals &= ~TYPE_QUAL_RESTRICT;
    }

  if (bad_quals == TYPE_UNQUALIFIED)
    /*OK*/;
  else if (!(complain & (tf_error | tf_ignore_bad_quals)))
    return error_mark_node;
  else
    {
      if (complain & tf_ignore_bad_quals)
        /* We're not going to warn about constifying things that can't
           be constified.  */
        bad_quals &= ~TYPE_QUAL_CONST;
      if (bad_quals)
        {
          tree bad_type = build_qualified_type (ptr_type_node, bad_quals);

          if (!(complain & tf_ignore_bad_quals))
            error ("%qV qualifiers cannot be applied to %qT",
                   bad_type, type);
        }
    }

  /* Retrieve (or create) the appropriately qualified variant.  */
  result = build_qualified_type (type, type_quals);

  /* If this was a pointer-to-method type, and we just made a copy,
     then we need to unshare the record that holds the cached
     pointer-to-member-function type, because these will be distinct
     between the unqualified and qualified types.  */
  if (result != type
      && TREE_CODE (type) == POINTER_TYPE
      && TREE_CODE (TREE_TYPE (type)) == METHOD_TYPE)
    TYPE_LANG_SPECIFIC (result) = NULL;

  return result;
}

/* Returns the canonical version of TYPE.  In other words, if TYPE is
   a typedef, returns the underlying type.  The cv-qualification of
   the type returned matches the type input; they will always be
   compatible types.  */

tree
canonical_type_variant (tree t)
{
  return cp_build_qualified_type (TYPE_MAIN_VARIANT (t), cp_type_quals (t));
}
\f
/* Makes a copy of BINFO and TYPE, which is to be inherited into a
   graph dominated by T.  If BINFO is NULL, TYPE is a dependent base,
   and we do a shallow copy.  If BINFO is non-NULL, we do a deep copy.
   VIRT indicates whether TYPE is inherited virtually or not.
   IGO_PREV points at the previous binfo of the inheritance graph
   order chain.  The newly copied binfo's TREE_CHAIN forms this
   ordering.

   The CLASSTYPE_VBASECLASSES vector of T is constructed in the
   correct order. That is in the order the bases themselves should be
   constructed in.

   The BINFO_INHERITANCE of a virtual base class points to the binfo
   of the most derived type. ??? We could probably change this so that
   BINFO_INHERITANCE becomes synonymous with BINFO_PRIMARY, and hence
   remove a field.  They currently can only differ for primary virtual
   virtual bases.  */

tree
copy_binfo (tree binfo, tree type, tree t, tree *igo_prev, int virt)
{
  tree new_binfo;

  if (virt)
    {
      /* See if we've already made this virtual base.  */
      new_binfo = binfo_for_vbase (type, t);
      if (new_binfo)
        return new_binfo;
    }

  new_binfo = make_tree_binfo (binfo ? BINFO_N_BASE_BINFOS (binfo) : 0);
  BINFO_TYPE (new_binfo) = type;

  /* Chain it into the inheritance graph.  */
  TREE_CHAIN (*igo_prev) = new_binfo;
  *igo_prev = new_binfo;

  if (binfo)
    {
      int ix;
      tree base_binfo;

      gcc_assert (!BINFO_DEPENDENT_BASE_P (binfo));
      gcc_assert (SAME_BINFO_TYPE_P (BINFO_TYPE (binfo), type));

      BINFO_OFFSET (new_binfo) = BINFO_OFFSET (binfo);
      BINFO_VIRTUALS (new_binfo) = BINFO_VIRTUALS (binfo);

      /* We do not need to copy the accesses, as they are read only.  */
      BINFO_BASE_ACCESSES (new_binfo) = BINFO_BASE_ACCESSES (binfo);

      /* Recursively copy base binfos of BINFO.  */
      for (ix = 0; BINFO_BASE_ITERATE (binfo, ix, base_binfo); ix++)
        {
          tree new_base_binfo;

          gcc_assert (!BINFO_DEPENDENT_BASE_P (base_binfo));
          new_base_binfo = copy_binfo (base_binfo, BINFO_TYPE (base_binfo),
                                       t, igo_prev,
                                       BINFO_VIRTUAL_P (base_binfo));

          if (!BINFO_INHERITANCE_CHAIN (new_base_binfo))
            BINFO_INHERITANCE_CHAIN (new_base_binfo) = new_binfo;
          BINFO_BASE_APPEND (new_binfo, new_base_binfo);
        }
    }
  else
    BINFO_DEPENDENT_BASE_P (new_binfo) = 1;

  if (virt)
    {
      /* Push it onto the list after any virtual bases it contains
         will have been pushed.  */
      VEC_quick_push (tree, CLASSTYPE_VBASECLASSES (t), new_binfo);
      BINFO_VIRTUAL_P (new_binfo) = 1;
      BINFO_INHERITANCE_CHAIN (new_binfo) = TYPE_BINFO (t);
    }

  return new_binfo;
}
\f
/* Hashing of lists so that we don't make duplicates.
   The entry point is `list_hash_canon'.  */

/* Now here is the hash table.  When recording a list, it is added
   to the slot whose index is the hash code mod the table size.
   Note that the hash table is used for several kinds of lists.
   While all these live in the same table, they are completely independent,
   and the hash code is computed differently for each of these.  */

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

struct list_proxy
{
  tree purpose;
  tree value;
  tree chain;
};

/* Compare ENTRY (an entry in the hash table) with DATA (a list_proxy
   for a node we are thinking about adding).  */

static int
list_hash_eq (const void* entry, const void* data)
{
  const_tree const t = (const_tree) entry;
  const struct list_proxy *const proxy = (const struct list_proxy *) data;

  return (TREE_VALUE (t) == proxy->value
          && TREE_PURPOSE (t) == proxy->purpose
          && TREE_CHAIN (t) == proxy->chain);
}

/* Compute a hash code for a list (chain of TREE_LIST nodes
   with goodies in the TREE_PURPOSE, TREE_VALUE, and bits of the
   TREE_COMMON slots), by adding the hash codes of the individual entries.  */

static hashval_t
list_hash_pieces (tree purpose, tree value, tree chain)
{
  hashval_t hashcode = 0;

  if (chain)
    hashcode += TREE_HASH (chain);

  if (value)
    hashcode += TREE_HASH (value);
  else
    hashcode += 1007;
  if (purpose)
    hashcode += TREE_HASH (purpose);
  else
    hashcode += 1009;
  return hashcode;
}

/* Hash an already existing TREE_LIST.  */

static hashval_t
list_hash (const void* p)
{
  const_tree const t = (const_tree) p;
  return list_hash_pieces (TREE_PURPOSE (t),
                           TREE_VALUE (t),
                           TREE_CHAIN (t));
}

/* Given list components PURPOSE, VALUE, AND CHAIN, return the canonical
   object for an identical list if one already exists.  Otherwise, build a
   new one, and record it as the canonical object.  */

tree
hash_tree_cons (tree purpose, tree value, tree chain)
{
  int hashcode = 0;
  void **slot;
  struct list_proxy proxy;

  /* Hash the list node.  */
  hashcode = list_hash_pieces (purpose, value, chain);
  /* Create a proxy for the TREE_LIST we would like to create.  We
     don't actually create it so as to avoid creating garbage.  */
  proxy.purpose = purpose;
  proxy.value = value;
  proxy.chain = chain;
  /* See if it is already in the table.  */
  slot = htab_find_slot_with_hash (list_hash_table, &proxy, hashcode,
                                   INSERT);
  /* If not, create a new node.  */
  if (!*slot)
    *slot = tree_cons (purpose, value, chain);
  return (tree) *slot;
}

/* Constructor for hashed lists.  */

tree
hash_tree_chain (tree value, tree chain)
{
  return hash_tree_cons (NULL_TREE, value, chain);
}
\f
void
debug_binfo (tree elem)
{
  HOST_WIDE_INT n;
  tree virtuals;

  fprintf (stderr, "type \"%s\", offset = " HOST_WIDE_INT_PRINT_DEC
           "\nvtable type:\n",
           TYPE_NAME_STRING (BINFO_TYPE (elem)),
           TREE_INT_CST_LOW (BINFO_OFFSET (elem)));
  debug_tree (BINFO_TYPE (elem));
  if (BINFO_VTABLE (elem))
    fprintf (stderr, "vtable decl \"%s\"\n",
             IDENTIFIER_POINTER (DECL_NAME (get_vtbl_decl_for_binfo (elem))));
  else
    fprintf (stderr, "no vtable decl yet\n");
  fprintf (stderr, "virtuals:\n");
  virtuals = BINFO_VIRTUALS (elem);
  n = 0;

  while (virtuals)
    {
      tree fndecl = TREE_VALUE (virtuals);
      fprintf (stderr, "%s [%ld =? %ld]\n",
               IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (fndecl)),
               (long) n, (long) TREE_INT_CST_LOW (DECL_VINDEX (fndecl)));
      ++n;
      virtuals = TREE_CHAIN (virtuals);
    }
}

/* Build a representation for the qualified name SCOPE::NAME.  TYPE is
   the type of the result expression, if known, or NULL_TREE if the
   resulting expression is type-dependent.  If TEMPLATE_P is true,
   NAME is known to be a template because the user explicitly used the
   "template" keyword after the "::".

   All SCOPE_REFs should be built by use of this function.  */

tree
build_qualified_name (tree type, tree scope, tree name, bool template_p)
{
  tree t;
  if (type == error_mark_node
      || scope == error_mark_node
      || name == error_mark_node)
    return error_mark_node;
  t = build2 (SCOPE_REF, type, scope, name);
  QUALIFIED_NAME_IS_TEMPLATE (t) = template_p;
  return t;
}

/* Returns nonzero if X is an expression for a (possibly overloaded)
   function.  If "f" is a function or function template, "f", "c->f",
   "c.f", "C::f", and "f<int>" will all be considered possibly
   overloaded functions.  Returns 2 if the function is actually
   overloaded, i.e., if it is impossible to know the type of the
   function without performing overload resolution.  */
 
int
is_overloaded_fn (tree x)
{
  /* A baselink is also considered an overloaded function.  */
  if (TREE_CODE (x) == OFFSET_REF
      || TREE_CODE (x) == COMPONENT_REF)
    x = TREE_OPERAND (x, 1);
  if (BASELINK_P (x))
    x = BASELINK_FUNCTIONS (x);
  if (TREE_CODE (x) == TEMPLATE_ID_EXPR
      || DECL_FUNCTION_TEMPLATE_P (OVL_CURRENT (x))
      || (TREE_CODE (x) == OVERLOAD && OVL_CHAIN (x)))
    return 2;
  return  (TREE_CODE (x) == FUNCTION_DECL
           || TREE_CODE (x) == OVERLOAD);
}

/* Returns true iff X is an expression for an overloaded function
   whose type cannot be known without performing overload
   resolution.  */

bool
really_overloaded_fn (tree x)
{
  return is_overloaded_fn (x) == 2;
}

tree
get_first_fn (tree from)
{
  gcc_assert (is_overloaded_fn (from));
  /* A baselink is also considered an overloaded function.  */
  if (TREE_CODE (from) == COMPONENT_REF)
    from = TREE_OPERAND (from, 1);
  if (BASELINK_P (from))
    from = BASELINK_FUNCTIONS (from);
  return OVL_CURRENT (from);
}

/* Return a new OVL node, concatenating it with the old one.  */

tree
ovl_cons (tree decl, tree chain)
{
  tree result = make_node (OVERLOAD);
  TREE_TYPE (result) = unknown_type_node;
  OVL_FUNCTION (result) = decl;
  TREE_CHAIN (result) = chain;

  return result;
}

/* Build a new overloaded function. If this is the first one,
   just return it; otherwise, ovl_cons the _DECLs */

tree
build_overload (tree decl, tree chain)
{
  if (! chain && TREE_CODE (decl) != TEMPLATE_DECL)
    return decl;
  if (chain && TREE_CODE (chain) != OVERLOAD)
    chain = ovl_cons (chain, NULL_TREE);
  return ovl_cons (decl, chain);
}

\f
#define PRINT_RING_SIZE 4

const char *
cxx_printable_name (tree decl, int v)
{
  static unsigned int uid_ring[PRINT_RING_SIZE];
  static char *print_ring[PRINT_RING_SIZE];
  static int ring_counter;
  int i;

  /* Only cache functions.  */
  if (v < 2
      || TREE_CODE (decl) != FUNCTION_DECL
      || DECL_LANG_SPECIFIC (decl) == 0)
    return lang_decl_name (decl, v);

  /* See if this print name is lying around.  */
  for (i = 0; i < PRINT_RING_SIZE; i++)
    if (uid_ring[i] == DECL_UID (decl))
      /* yes, so return it.  */
      return print_ring[i];

  if (++ring_counter == PRINT_RING_SIZE)
    ring_counter = 0;

  if (current_function_decl != NULL_TREE)
    {
      if (uid_ring[ring_counter] == DECL_UID (current_function_decl))
        ring_counter += 1;
      if (ring_counter == PRINT_RING_SIZE)
        ring_counter = 0;
      gcc_assert (uid_ring[ring_counter] != DECL_UID (current_function_decl));
    }

  if (print_ring[ring_counter])
    free (print_ring[ring_counter]);

  print_ring[ring_counter] = xstrdup (lang_decl_name (decl, v));
  uid_ring[ring_counter] = DECL_UID (decl);
  return print_ring[ring_counter];
}
\f
/* Build the FUNCTION_TYPE or METHOD_TYPE which may throw exceptions
   listed in RAISES.  */

tree
build_exception_variant (tree type, tree raises)
{
  tree v = TYPE_MAIN_VARIANT (type);
  int type_quals = TYPE_QUALS (type);

  for (; v; v = TYPE_NEXT_VARIANT (v))
    if (check_qualified_type (v, type, type_quals)
        && comp_except_specs (raises, TYPE_RAISES_EXCEPTIONS (v), 1))
      return v;

  /* Need to build a new variant.  */
  v = build_variant_type_copy (type);
  TYPE_RAISES_EXCEPTIONS (v) = raises;
  return v;
}

/* Given a TEMPLATE_TEMPLATE_PARM node T, create a new
   BOUND_TEMPLATE_TEMPLATE_PARM bound with NEWARGS as its template
   arguments.  */

tree
bind_template_template_parm (tree t, tree newargs)
{
  tree decl = TYPE_NAME (t);
  tree t2;

  t2 = make_aggr_type (BOUND_TEMPLATE_TEMPLATE_PARM);
  decl = build_decl (TYPE_DECL, DECL_NAME (decl), NULL_TREE);

  /* These nodes have to be created to reflect new TYPE_DECL and template
     arguments.  */
  TEMPLATE_TYPE_PARM_INDEX (t2) = copy_node (TEMPLATE_TYPE_PARM_INDEX (t));
  TEMPLATE_PARM_DECL (TEMPLATE_TYPE_PARM_INDEX (t2)) = decl;
  TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (t2)
    = tree_cons (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t),
                 newargs, NULL_TREE);

  TREE_TYPE (decl) = t2;
  TYPE_NAME (t2) = decl;
  TYPE_STUB_DECL (t2) = decl;
  TYPE_SIZE (t2) = 0;
  SET_TYPE_STRUCTURAL_EQUALITY (t2);

  return t2;
}

/* Called from count_trees via walk_tree.  */

static tree
count_trees_r (tree *tp, int *walk_subtrees, void *data)
{
  ++*((int *) data);

  if (TYPE_P (*tp))
    *walk_subtrees = 0;

  return NULL_TREE;
}

/* Debugging function for measuring the rough complexity of a tree
   representation.  */

int
count_trees (tree t)
{
  int n_trees = 0;
  cp_walk_tree_without_duplicates (&t, count_trees_r, &n_trees);
  return n_trees;
}

/* Called from verify_stmt_tree via walk_tree.  */

static tree
verify_stmt_tree_r (tree* tp,
                    int* walk_subtrees ATTRIBUTE_UNUSED ,
                    void* data)
{
  tree t = *tp;
  htab_t *statements = (htab_t *) data;
  void **slot;

  if (!STATEMENT_CODE_P (TREE_CODE (t)))
    return NULL_TREE;

  /* If this statement is already present in the hash table, then
     there is a circularity in the statement tree.  */
  gcc_assert (!htab_find (*statements, t));

  slot = htab_find_slot (*statements, t, INSERT);
  *slot = t;

  return NULL_TREE;
}

/* Debugging function to check that the statement T has not been
   corrupted.  For now, this function simply checks that T contains no
   circularities.  */

void
verify_stmt_tree (tree t)
{
  htab_t statements;
  statements = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
  cp_walk_tree (&t, verify_stmt_tree_r, &statements, NULL);
  htab_delete (statements);
}

/* Check if the type T depends on a type with no linkage and if so, return
   it.  If RELAXED_P then do not consider a class type declared within
   a TREE_PUBLIC function to have no linkage.  */

tree
no_linkage_check (tree t, bool relaxed_p)
{
  tree r;

  /* There's no point in checking linkage on template functions; we
     can't know their complete types.  */
  if (processing_template_decl)
    return NULL_TREE;

  switch (TREE_CODE (t))
    {
      tree fn;

    case RECORD_TYPE:
      if (TYPE_PTRMEMFUNC_P (t))
        goto ptrmem;
      /* Fall through.  */
    case UNION_TYPE:
      if (!CLASS_TYPE_P (t))
        return NULL_TREE;
      /* Fall through.  */
    case ENUMERAL_TYPE:
      if (TYPE_ANONYMOUS_P (t))
        return t;
      fn = decl_function_context (TYPE_MAIN_DECL (t));
      if (fn && (!relaxed_p || !TREE_PUBLIC (fn)))
        return t;
      return NULL_TREE;

    case ARRAY_TYPE:
    case POINTER_TYPE:
    case REFERENCE_TYPE:
      return no_linkage_check (TREE_TYPE (t), relaxed_p);

    case OFFSET_TYPE:
    ptrmem:
      r = no_linkage_check (TYPE_PTRMEM_POINTED_TO_TYPE (t),
                            relaxed_p);
      if (r)
        return r;
      return no_linkage_check (TYPE_PTRMEM_CLASS_TYPE (t), relaxed_p);

    case METHOD_TYPE:
      r = no_linkage_check (TYPE_METHOD_BASETYPE (t), relaxed_p);
      if (r)
        return r;
      /* Fall through.  */
    case FUNCTION_TYPE:
      {
        tree parm;
        for (parm = TYPE_ARG_TYPES (t);
             parm && parm != void_list_node;
             parm = TREE_CHAIN (parm))
          {
            r = no_linkage_check (TREE_VALUE (parm), relaxed_p);
            if (r)
              return r;
          }
        return no_linkage_check (TREE_TYPE (t), relaxed_p);
      }

    default:
      return NULL_TREE;
    }
}

#ifdef GATHER_STATISTICS
extern int depth_reached;
#endif

void
cxx_print_statistics (void)
{
  print_search_statistics ();
  print_class_statistics ();
#ifdef GATHER_STATISTICS
  fprintf (stderr, "maximum template instantiation depth reached: %d\n",
           depth_reached);
#endif
}

/* Return, as an INTEGER_CST node, the number of elements for TYPE
   (which is an ARRAY_TYPE).  This counts only elements of the top
   array.  */

tree
array_type_nelts_top (tree type)
{
  return fold_build2 (PLUS_EXPR, sizetype,
                      array_type_nelts (type),
                      integer_one_node);
}

/* Return, as an INTEGER_CST node, the number of elements for TYPE
   (which is an ARRAY_TYPE).  This one is a recursive count of all
   ARRAY_TYPEs that are clumped together.  */

tree
array_type_nelts_total (tree type)
{
  tree sz = array_type_nelts_top (type);
  type = TREE_TYPE (type);
  while (TREE_CODE (type) == ARRAY_TYPE)
    {
      tree n = array_type_nelts_top (type);
      sz = fold_build2 (MULT_EXPR, sizetype, sz, n);
      type = TREE_TYPE (type);
    }
  return sz;
}

/* Called from break_out_target_exprs via mapcar.  */

static tree
bot_manip (tree* tp, int* walk_subtrees, void* data)
{
  splay_tree target_remap = ((splay_tree) data);
  tree t = *tp;

  if (!TYPE_P (t) && TREE_CONSTANT (t))
    {
      /* There can't be any TARGET_EXPRs or their slot variables below
         this point.  We used to check !TREE_SIDE_EFFECTS, but then we
         failed to copy an ADDR_EXPR of the slot VAR_DECL.  */
      *walk_subtrees = 0;
      return NULL_TREE;
    }
  if (TREE_CODE (t) == TARGET_EXPR)
    {
      tree u;

      if (TREE_CODE (TREE_OPERAND (t, 1)) == AGGR_INIT_EXPR)
        u = build_cplus_new
          (TREE_TYPE (t), break_out_target_exprs (TREE_OPERAND (t, 1)));
      else
        u = build_target_expr_with_type
          (break_out_target_exprs (TREE_OPERAND (t, 1)), TREE_TYPE (t));

      /* Map the old variable to the new one.  */
      splay_tree_insert (target_remap,
                         (splay_tree_key) TREE_OPERAND (t, 0),
                         (splay_tree_value) TREE_OPERAND (u, 0));

      /* Replace the old expression with the new version.  */
      *tp = u;
      /* We don't have to go below this point; the recursive call to
         break_out_target_exprs will have handled anything below this
         point.  */
      *walk_subtrees = 0;
      return NULL_TREE;
    }

  /* Make a copy of this node.  */
  return copy_tree_r (tp, walk_subtrees, NULL);
}

/* Replace all remapped VAR_DECLs in T with their new equivalents.
   DATA is really a splay-tree mapping old variables to new
   variables.  */

static tree
bot_replace (tree* t,
             int* walk_subtrees ATTRIBUTE_UNUSED ,
             void* data)
{
  splay_tree target_remap = ((splay_tree) data);

  if (TREE_CODE (*t) == VAR_DECL)
    {
      splay_tree_node n = splay_tree_lookup (target_remap,
                                             (splay_tree_key) *t);
      if (n)
        *t = (tree) n->value;
    }

  return NULL_TREE;
}

/* When we parse a default argument expression, we may create
   temporary variables via TARGET_EXPRs.  When we actually use the
   default-argument expression, we make a copy of the expression, but
   we must replace the temporaries with appropriate local versions.  */

tree
break_out_target_exprs (tree t)
{
  static int target_remap_count;
  static splay_tree target_remap;

  if (!target_remap_count++)
    target_remap = splay_tree_new (splay_tree_compare_pointers,
                                   /*splay_tree_delete_key_fn=*/NULL,
                                   /*splay_tree_delete_value_fn=*/NULL);
  cp_walk_tree (&t, bot_manip, target_remap, NULL);
  cp_walk_tree (&t, bot_replace, target_remap, NULL);

  if (!--target_remap_count)
    {
      splay_tree_delete (target_remap);
      target_remap = NULL;
    }

  return t;
}

/* Similar to `build_nt', but for template definitions of dependent
   expressions  */

tree
build_min_nt (enum tree_code code, ...)
{
  tree t;
  int length;
  int i;
  va_list p;

  gcc_assert (TREE_CODE_CLASS (code) != tcc_vl_exp);

  va_start (p, code);

  t = make_node (code);
  length = TREE_CODE_LENGTH (code);

  for (i = 0; i < length; i++)
    {
      tree x = va_arg (p, tree);
      TREE_OPERAND (t, i) = x;
    }

  va_end (p);
  return t;
}


/* Similar to `build', but for template definitions.  */

tree
build_min (enum tree_code code, tree tt, ...)
{
  tree t;
  int length;
  int i;
  va_list p;

  gcc_assert (TREE_CODE_CLASS (code) != tcc_vl_exp);

  va_start (p, tt);

  t = make_node (code);
  length = TREE_CODE_LENGTH (code);
  TREE_TYPE (t) = tt;

  for (i = 0; i < length; i++)
    {
      tree x = va_arg (p, tree);
      TREE_OPERAND (t, i) = x;
      if (x && !TYPE_P (x) && TREE_SIDE_EFFECTS (x))
        TREE_SIDE_EFFECTS (t) = 1;
    }

  va_end (p);
  return t;
}

/* Similar to `build', but for template definitions of non-dependent
   expressions. NON_DEP is the non-dependent expression that has been
   built.  */

tree
build_min_non_dep (enum tree_code code, tree non_dep, ...)
{
  tree t;
  int length;
  int i;
  va_list p;

  gcc_assert (TREE_CODE_CLASS (code) != tcc_vl_exp);

  va_start (p, non_dep);

  t = make_node (code);
  length = TREE_CODE_LENGTH (code);
  TREE_TYPE (t) = TREE_TYPE (non_dep);
  TREE_SIDE_EFFECTS (t) = TREE_SIDE_EFFECTS (non_dep);

  for (i = 0; i < length; i++)
    {
      tree x = va_arg (p, tree);
      TREE_OPERAND (t, i) = x;
    }

  if (code == COMPOUND_EXPR && TREE_CODE (non_dep) != COMPOUND_EXPR)
    /* This should not be considered a COMPOUND_EXPR, because it
       resolves to an overload.  */
    COMPOUND_EXPR_OVERLOADED (t) = 1;

  va_end (p);
  return t;
}

/* Similar to `build_call_list', but for template definitions of non-dependent
   expressions. NON_DEP is the non-dependent expression that has been
   built.  */

tree
build_min_non_dep_call_list (tree non_dep, tree fn, tree arglist)
{
  tree t = build_nt_call_list (fn, arglist);
  TREE_TYPE (t) = TREE_TYPE (non_dep);
  TREE_SIDE_EFFECTS (t) = TREE_SIDE_EFFECTS (non_dep);
  return t;
}

tree
get_type_decl (tree t)
{
  if (TREE_CODE (t) == TYPE_DECL)
    return t;
  if (TYPE_P (t))
    return TYPE_STUB_DECL (t);
  gcc_assert (t == error_mark_node);
  return t;
}

/* Returns the namespace that contains DECL, whether directly or
   indirectly.  */

tree
decl_namespace_context (tree decl)
{
  while (1)
    {
      if (TREE_CODE (decl) == NAMESPACE_DECL)
        return decl;
      else if (TYPE_P (decl))
        decl = CP_DECL_CONTEXT (TYPE_MAIN_DECL (decl));
      else
        decl = CP_DECL_CONTEXT (decl);
    }
}

/* Returns true if decl is within an anonymous namespace, however deeply
   nested, or false otherwise.  */

bool
decl_anon_ns_mem_p (const_tree decl)
{
  while (1)
    {
      if (decl == NULL_TREE || decl == error_mark_node)
        return false;
      if (TREE_CODE (decl) == NAMESPACE_DECL
          && DECL_NAME (decl) == NULL_TREE)
        return true;
      /* Classes and namespaces inside anonymous namespaces have
         TREE_PUBLIC == 0, so we can shortcut the search.  */
      else if (TYPE_P (decl))
        return (TREE_PUBLIC (TYPE_NAME (decl)) == 0);
      else if (TREE_CODE (decl) == NAMESPACE_DECL)
        return (TREE_PUBLIC (decl) == 0);
      else
        decl = DECL_CONTEXT (decl);
    }
}

/* Return truthvalue of whether T1 is the same tree structure as T2.
   Return 1 if they are the same. Return 0 if they are different.  */

bool
cp_tree_equal (tree t1, tree t2)
{
  enum tree_code code1, code2;

  if (t1 == t2)
    return true;
  if (!t1 || !t2)
    return false;

  for (code1 = TREE_CODE (t1);
       code1 == NOP_EXPR || code1 == CONVERT_EXPR
         || code1 == NON_LVALUE_EXPR;
       code1 = TREE_CODE (t1))
    t1 = TREE_OPERAND (t1, 0);
  for (code2 = TREE_CODE (t2);
       code2 == NOP_EXPR || code2 == CONVERT_EXPR
         || code1 == NON_LVALUE_EXPR;
       code2 = TREE_CODE (t2))
    t2 = TREE_OPERAND (t2, 0);

  /* They might have become equal now.  */
  if (t1 == t2)
    return true;

  if (code1 != code2)
    return false;

  switch (code1)
    {
    case INTEGER_CST:
      return TREE_INT_CST_LOW (t1) == TREE_INT_CST_LOW (t2)
        && TREE_INT_CST_HIGH (t1) == TREE_INT_CST_HIGH (t2);

    case REAL_CST:
      return REAL_VALUES_EQUAL (TREE_REAL_CST (t1), TREE_REAL_CST (t2));

    case STRING_CST:
      return TREE_STRING_LENGTH (t1) == TREE_STRING_LENGTH (t2)
        && !memcmp (TREE_STRING_POINTER (t1), TREE_STRING_POINTER (t2),
                    TREE_STRING_LENGTH (t1));

    case COMPLEX_CST:
      return cp_tree_equal (TREE_REALPART (t1), TREE_REALPART (t2))
        && cp_tree_equal (TREE_IMAGPART (t1), TREE_IMAGPART (t2));

    case CONSTRUCTOR:
      /* We need to do this when determining whether or not two
         non-type pointer to member function template arguments
         are the same.  */
      if (!(same_type_p (TREE_TYPE (t1), TREE_TYPE (t2))
            /* The first operand is RTL.  */
            && TREE_OPERAND (t1, 0) == TREE_OPERAND (t2, 0)))
        return false;
      return cp_tree_equal (TREE_OPERAND (t1, 1), TREE_OPERAND (t2, 1));

    case TREE_LIST:
      if (!cp_tree_equal (TREE_PURPOSE (t1), TREE_PURPOSE (t2)))
        return false;
      if (!cp_tree_equal (TREE_VALUE (t1), TREE_VALUE (t2)))
        return false;
      return cp_tree_equal (TREE_CHAIN (t1), TREE_CHAIN (t2));

    case SAVE_EXPR:
      return cp_tree_equal (TREE_OPERAND (t1, 0), TREE_OPERAND (t2, 0));

    case CALL_EXPR:
      {
        tree arg1, arg2;
        call_expr_arg_iterator iter1, iter2;
        if (!cp_tree_equal (CALL_EXPR_FN (t1), CALL_EXPR_FN (t2)))
          return false;
        for (arg1 = first_call_expr_arg (t1, &iter1),
               arg2 = first_call_expr_arg (t2, &iter2);
             arg1 && arg2;
             arg1 = next_call_expr_arg (&iter1),
               arg2 = next_call_expr_arg (&iter2))
          if (!cp_tree_equal (arg1, arg2))
            return false;
        return (arg1 || arg2);
      }

    case TARGET_EXPR:
      {
        tree o1 = TREE_OPERAND (t1, 0);
        tree o2 = TREE_OPERAND (t2, 0);

        /* Special case: if either target is an unallocated VAR_DECL,
           it means that it's going to be unified with whatever the
           TARGET_EXPR is really supposed to initialize, so treat it
           as being equivalent to anything.  */
        if (TREE_CODE (o1) == VAR_DECL && DECL_NAME (o1) == NULL_TREE
            && !DECL_RTL_SET_P (o1))
          /*Nop*/;
        else if (TREE_CODE (o2) == VAR_DECL && DECL_NAME (o2) == NULL_TREE
                 && !DECL_RTL_SET_P (o2))
          /*Nop*/;
        else if (!cp_tree_equal (o1, o2))
          return false;

        return cp_tree_equal (TREE_OPERAND (t1, 1), TREE_OPERAND (t2, 1));
      }

    case WITH_CLEANUP_EXPR:
      if (!cp_tree_equal (TREE_OPERAND (t1, 0), TREE_OPERAND (t2, 0)))
        return false;
      return cp_tree_equal (TREE_OPERAND (t1, 1), TREE_OPERAND (t1, 1));

    case COMPONENT_REF:
      if (TREE_OPERAND (t1, 1) != TREE_OPERAND (t2, 1))
        return false;
      return cp_tree_equal (TREE_OPERAND (t1, 0), TREE_OPERAND (t2, 0));

    case VAR_DECL:
    case PARM_DECL:
    case CONST_DECL:
    case FUNCTION_DECL:
    case TEMPLATE_DECL:
    case IDENTIFIER_NODE:
    case SSA_NAME:
      return false;

    case BASELINK:
      return (BASELINK_BINFO (t1) == BASELINK_BINFO (t2)
              && BASELINK_ACCESS_BINFO (t1) == BASELINK_ACCESS_BINFO (t2)
              && cp_tree_equal (BASELINK_FUNCTIONS (t1),
                                BASELINK_FUNCTIONS (t2)));

    case TEMPLATE_PARM_INDEX:
      return (TEMPLATE_PARM_IDX (t1) == TEMPLATE_PARM_IDX (t2)
              && TEMPLATE_PARM_LEVEL (t1) == TEMPLATE_PARM_LEVEL (t2)
              && same_type_p (TREE_TYPE (TEMPLATE_PARM_DECL (t1)),
                              TREE_TYPE (TEMPLATE_PARM_DECL (t2))));

    case TEMPLATE_ID_EXPR:
      {
        unsigned ix;
        tree vec1, vec2;

        if (!cp_tree_equal (TREE_OPERAND (t1, 0), TREE_OPERAND (t2, 0)))
          return false;
        vec1 = TREE_OPERAND (t1, 1);
        vec2 = TREE_OPERAND (t2, 1);

        if (!vec1 || !vec2)
          return !vec1 && !vec2;

        if (TREE_VEC_LENGTH (vec1) != TREE_VEC_LENGTH (vec2))
          return false;

        for (ix = TREE_VEC_LENGTH (vec1); ix--;)
          if (!cp_tree_equal (TREE_VEC_ELT (vec1, ix),
                              TREE_VEC_ELT (vec2, ix)))
            return false;

        return true;
      }

    case SIZEOF_EXPR:
    case ALIGNOF_EXPR:
      {
        tree o1 = TREE_OPERAND (t1, 0);
        tree o2 = TREE_OPERAND (t2, 0);

        if (TREE_CODE (o1) != TREE_CODE (o2))
          return false;
        if (TYPE_P (o1))
          return same_type_p (o1, o2);
        else
          return cp_tree_equal (o1, o2);
      }

    case MODOP_EXPR:
      {
        tree t1_op1, t2_op1;

        if (!cp_tree_equal (TREE_OPERAND (t1, 0), TREE_OPERAND (t2, 0)))
          return false;

        t1_op1 = TREE_OPERAND (t1, 1);
        t2_op1 = TREE_OPERAND (t2, 1);
        if (TREE_CODE (t1_op1) != TREE_CODE (t2_op1))
          return false;

        return cp_tree_equal (TREE_OPERAND (t1, 2), TREE_OPERAND (t2, 2));
      }

    case PTRMEM_CST:
      /* Two pointer-to-members are the same if they point to the same
         field or function in the same class.  */
      if (PTRMEM_CST_MEMBER (t1) != PTRMEM_CST_MEMBER (t2))
        return false;

      return same_type_p (PTRMEM_CST_CLASS (t1), PTRMEM_CST_CLASS (t2));

    case OVERLOAD:
      if (OVL_FUNCTION (t1) != OVL_FUNCTION (t2))
        return false;
      return cp_tree_equal (OVL_CHAIN (t1), OVL_CHAIN (t2));

    case TRAIT_EXPR:
      if (TRAIT_EXPR_KIND (t1) != TRAIT_EXPR_KIND (t2))
        return false;
      return same_type_p (TRAIT_EXPR_TYPE1 (t1), TRAIT_EXPR_TYPE1 (t2))
        && same_type_p (TRAIT_EXPR_TYPE2 (t1), TRAIT_EXPR_TYPE2 (t2));

    default:
      break;
    }

  switch (TREE_CODE_CLASS (code1))
    {
    case tcc_unary:
    case tcc_binary:
    case tcc_comparison:
    case tcc_expression:
    case tcc_vl_exp:
    case tcc_reference:
    case tcc_statement:
      {
        int i, n;

        n = TREE_OPERAND_LENGTH (t1);
        if (TREE_CODE_CLASS (code1) == tcc_vl_exp
            && n != TREE_OPERAND_LENGTH (t2))
          return false;

        for (i = 0; i < n; ++i)
          if (!cp_tree_equal (TREE_OPERAND (t1, i), TREE_OPERAND (t2, i)))
            return false;

        return true;
      }

    case tcc_type:
      return same_type_p (t1, t2);
    default:
      gcc_unreachable ();
    }
  /* We can get here with --disable-checking.  */
  return false;
}

/* The type of ARG when used as an lvalue.  */

tree
lvalue_type (tree arg)
{
  tree type = TREE_TYPE (arg);
  return type;
}

/* The type of ARG for printing error messages; denote lvalues with
   reference types.  */

tree
error_type (tree arg)
{
  tree type = TREE_TYPE (arg);

  if (TREE_CODE (type) == ARRAY_TYPE)
    ;
  else if (TREE_CODE (type) == ERROR_MARK)
    ;
  else if (real_lvalue_p (arg))
    type = build_reference_type (lvalue_type (arg));
  else if (IS_AGGR_TYPE (type))
    type = lvalue_type (arg);

  return type;
}

/* Does FUNCTION use a variable-length argument list?  */

int
varargs_function_p (const_tree function)
{
  const_tree parm = TYPE_ARG_TYPES (TREE_TYPE (function));
  for (; parm; parm = TREE_CHAIN (parm))
    if (TREE_VALUE (parm) == void_type_node)
      return 0;
  return 1;
}

/* Returns 1 if decl is a member of a class.  */

int
member_p (const_tree decl)
{
  const_tree const ctx = DECL_CONTEXT (decl);
  return (ctx && TYPE_P (ctx));
}

/* Create a placeholder for member access where we don't actually have an
   object that the access is against.  */

tree
build_dummy_object (tree type)
{
  tree decl = build1 (NOP_EXPR, build_pointer_type (type), void_zero_node);
  return build_indirect_ref (decl, NULL);
}

/* We've gotten a reference to a member of TYPE.  Return *this if appropriate,
   or a dummy object otherwise.  If BINFOP is non-0, it is filled with the
   binfo path from current_class_type to TYPE, or 0.  */

tree
maybe_dummy_object (tree type, tree* binfop)
{
  tree decl, context;
  tree binfo;

  if (current_class_type
      && (binfo = lookup_base (current_class_type, type,
                               ba_unique | ba_quiet, NULL)))
    context = current_class_type;
  else
    {
      /* Reference from a nested class member function.  */
      context = type;
      binfo = TYPE_BINFO (type);
    }

  if (binfop)
    *binfop = binfo;

  if (current_class_ref && context == current_class_type
      /* Kludge: Make sure that current_class_type is actually
         correct.  It might not be if we're in the middle of
         tsubst_default_argument.  */
      && same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (current_class_ref)),
                      current_class_type))
    decl = current_class_ref;
  else
    decl = build_dummy_object (context);

  return decl;
}

/* Returns 1 if OB is a placeholder object, or a pointer to one.  */

int
is_dummy_object (const_tree ob)
{
  if (TREE_CODE (ob) == INDIRECT_REF)
    ob = TREE_OPERAND (ob, 0);
  return (TREE_CODE (ob) == NOP_EXPR
          && TREE_OPERAND (ob, 0) == void_zero_node);
}

/* Returns 1 iff type T is a POD type, as defined in [basic.types].  */

int
pod_type_p (const_tree t)
{
  /* This CONST_CAST is okay because strip_array_types returns it's
     argument unmodified and we assign it to a const_tree.  */
  t = strip_array_types (CONST_CAST_TREE(t));

  if (t == error_mark_node)
    return 1;
  if (INTEGRAL_TYPE_P (t))
    return 1;  /* integral, character or enumeral type */
  if (FLOAT_TYPE_P (t))
    return 1;
  if (TYPE_PTR_P (t))
    return 1; /* pointer to non-member */
  if (TYPE_PTR_TO_MEMBER_P (t))
    return 1; /* pointer to member */

  if (TREE_CODE (t) == VECTOR_TYPE)
    return 1; /* vectors are (small) arrays of scalars */

  if (! CLASS_TYPE_P (t))
    return 0; /* other non-class type (reference or function) */
  if (CLASSTYPE_NON_POD_P (t))
    return 0;
  return 1;
}

/* Nonzero iff type T is a class template implicit specialization.  */

bool
class_tmpl_impl_spec_p (const_tree t)
{
  return CLASS_TYPE_P (t) && CLASSTYPE_TEMPLATE_INSTANTIATION (t);
}

/* Returns 1 iff zero initialization of type T means actually storing
   zeros in it.  */

int
zero_init_p (const_tree t)
{
  /* This CONST_CAST is okay because strip_array_types returns it's
     argument unmodified and we assign it to a const_tree.  */
  t = strip_array_types (CONST_CAST_TREE(t));

  if (t == error_mark_node)
    return 1;

  /* NULL pointers to data members are initialized with -1.  */
  if (TYPE_PTRMEM_P (t))
    return 0;

  /* Classes that contain types that can't be zero-initialized, cannot
     be zero-initialized themselves.  */
  if (CLASS_TYPE_P (t) && CLASSTYPE_NON_ZERO_INIT_P (t))
    return 0;

  return 1;
}

/* Table of valid C++ attributes.  */
const struct attribute_spec cxx_attribute_table[] =
{
  /* { name, min_len, max_len, decl_req, type_req, fn_type_req, handler } */
  { "java_interface", 0, 0, false, false, false, handle_java_interface_attribute },
  { "com_interface",  0, 0, false, false, false, handle_com_interface_attribute },
  { "init_priority",  1, 1, true,  false, false, handle_init_priority_attribute },
  { NULL,             0, 0, false, false, false, NULL }
};

/* Handle a "java_interface" attribute; arguments as in
   struct attribute_spec.handler.  */
static tree
handle_java_interface_attribute (tree* node,
                                 tree name,
                                 tree args ATTRIBUTE_UNUSED ,
                                 int flags,
                                 bool* no_add_attrs)
{
  if (DECL_P (*node)
      || !CLASS_TYPE_P (*node)
      || !TYPE_FOR_JAVA (*node))
    {
      error ("%qE attribute can only be applied to Java class definitions",
             name);
      *no_add_attrs = true;
      return NULL_TREE;
    }
  if (!(flags & (int) ATTR_FLAG_TYPE_IN_PLACE))
    *node = build_variant_type_copy (*node);
  TYPE_JAVA_INTERFACE (*node) = 1;

  return NULL_TREE;
}

/* Handle a "com_interface" attribute; arguments as in
   struct attribute_spec.handler.  */
static tree
handle_com_interface_attribute (tree* node,
                                tree name,
                                tree args ATTRIBUTE_UNUSED ,
                                int flags ATTRIBUTE_UNUSED ,
                                bool* no_add_attrs)
{
  static int warned;

  *no_add_attrs = true;

  if (DECL_P (*node)
      || !CLASS_TYPE_P (*node)
      || *node != TYPE_MAIN_VARIANT (*node))
    {
      warning (OPT_Wattributes, "%qE attribute can only be applied "
               "to class definitions", name);
      return NULL_TREE;
    }

  if (!warned++)
    warning (0, "%qE is obsolete; g++ vtables are now COM-compatible by default",
             name);

  return NULL_TREE;
}

/* Handle an "init_priority" attribute; arguments as in
   struct attribute_spec.handler.  */
static tree
handle_init_priority_attribute (tree* node,
                                tree name,
                                tree args,
                                int flags ATTRIBUTE_UNUSED ,
                                bool* no_add_attrs)
{
  tree initp_expr = TREE_VALUE (args);
  tree decl = *node;
  tree type = TREE_TYPE (decl);
  int pri;

  STRIP_NOPS (initp_expr);

  if (!initp_expr || TREE_CODE (initp_expr) != INTEGER_CST)
    {
      error ("requested init_priority is not an integer constant");
      *no_add_attrs = true;
      return NULL_TREE;
    }

  pri = TREE_INT_CST_LOW (initp_expr);

  type = strip_array_types (type);

  if (decl == NULL_TREE
      || TREE_CODE (decl) != VAR_DECL
      || !TREE_STATIC (decl)
      || DECL_EXTERNAL (decl)
      || (TREE_CODE (type) != RECORD_TYPE
          && TREE_CODE (type) != UNION_TYPE)
      /* Static objects in functions are initialized the
         first time control passes through that
         function. This is not precise enough to pin down an
         init_priority value, so don't allow it.  */
      || current_function_decl)
    {
      error ("can only use %qE attribute on file-scope definitions "
             "of objects of class type", name);
      *no_add_attrs = true;
      return NULL_TREE;
    }

  if (pri > MAX_INIT_PRIORITY || pri <= 0)
    {
      error ("requested init_priority is out of range");
      *no_add_attrs = true;
      return NULL_TREE;
    }

  /* Check for init_priorities that are reserved for
     language and runtime support implementations.*/
  if (pri <= MAX_RESERVED_INIT_PRIORITY)
    {
      warning
        (0, "requested init_priority is reserved for internal use");
    }

  if (SUPPORTS_INIT_PRIORITY)
    {
      SET_DECL_INIT_PRIORITY (decl, pri);
      DECL_HAS_INIT_PRIORITY_P (decl) = 1;
      return NULL_TREE;
    }
  else
    {
      error ("%qE attribute is not supported on this platform", name);
      *no_add_attrs = true;
      return NULL_TREE;
    }
}

/* Return a new PTRMEM_CST of the indicated TYPE.  The MEMBER is the
   thing pointed to by the constant.  */

tree
make_ptrmem_cst (tree type, tree member)
{
  tree ptrmem_cst = make_node (PTRMEM_CST);
  TREE_TYPE (ptrmem_cst) = type;
  PTRMEM_CST_MEMBER (ptrmem_cst) = member;
  return ptrmem_cst;
}

/* Build a variant of TYPE that has the indicated ATTRIBUTES.  May
   return an existing type if an appropriate type already exists.  */

tree
cp_build_type_attribute_variant (tree type, tree attributes)
{
  tree new_type;

  new_type = build_type_attribute_variant (type, attributes);
  if (TREE_CODE (new_type) == FUNCTION_TYPE
      && (TYPE_RAISES_EXCEPTIONS (new_type)
          != TYPE_RAISES_EXCEPTIONS (type)))
    new_type = build_exception_variant (new_type,
                                        TYPE_RAISES_EXCEPTIONS (type));

  /* Making a new main variant of a class type is broken.  */
  gcc_assert (!CLASS_TYPE_P (type) || new_type == type);
    
  return new_type;
}

/* Return TRUE if TYPE1 and TYPE2 are identical for type hashing purposes.
   Called only after doing all language independent checks.  Only
   to check TYPE_RAISES_EXCEPTIONS for FUNCTION_TYPE, the rest is already
   compared in type_hash_eq.  */

bool
cxx_type_hash_eq (const_tree typea, const_tree typeb)
{
  gcc_assert (TREE_CODE (typea) == FUNCTION_TYPE);

  return comp_except_specs (TYPE_RAISES_EXCEPTIONS (typea),
                            TYPE_RAISES_EXCEPTIONS (typeb), 1);
}

/* Apply FUNC to all language-specific sub-trees of TP in a pre-order
   traversal.  Called from walk_tree.  */

tree
cp_walk_subtrees (tree *tp, int *walk_subtrees_p, walk_tree_fn func,
                  void *data, struct pointer_set_t *pset)
{
  enum tree_code code = TREE_CODE (*tp);
  tree result;

#define WALK_SUBTREE(NODE)                              \
  do                                                    \
    {                                                   \
      result = cp_walk_tree (&(NODE), func, data, pset);        \
      if (result) goto out;                             \
    }                                                   \
  while (0)

  /* Not one of the easy cases.  We must explicitly go through the
     children.  */
  result = NULL_TREE;
  switch (code)
    {
    case DEFAULT_ARG:
    case TEMPLATE_TEMPLATE_PARM:
    case BOUND_TEMPLATE_TEMPLATE_PARM:
    case UNBOUND_CLASS_TEMPLATE:
    case TEMPLATE_PARM_INDEX:
    case TEMPLATE_TYPE_PARM:
    case TYPENAME_TYPE:
    case TYPEOF_TYPE:
      /* None of these have subtrees other than those already walked
         above.  */
      *walk_subtrees_p = 0;
      break;

    case BASELINK:
      WALK_SUBTREE (BASELINK_FUNCTIONS (*tp));
      *walk_subtrees_p = 0;
      break;

    case PTRMEM_CST:
      WALK_SUBTREE (TREE_TYPE (*tp));
      *walk_subtrees_p = 0;
      break;

    case TREE_LIST:
      WALK_SUBTREE (TREE_PURPOSE (*tp));
      break;

    case OVERLOAD:
      WALK_SUBTREE (OVL_FUNCTION (*tp));
      WALK_SUBTREE (OVL_CHAIN (*tp));
      *walk_subtrees_p = 0;
      break;

    case RECORD_TYPE:
      if (TYPE_PTRMEMFUNC_P (*tp))
        WALK_SUBTREE (TYPE_PTRMEMFUNC_FN_TYPE (*tp));
      break;

    case TYPE_ARGUMENT_PACK:
    case NONTYPE_ARGUMENT_PACK:
      {
        tree args = ARGUMENT_PACK_ARGS (*tp);
        int i, len = TREE_VEC_LENGTH (args);
        for (i = 0; i < len; i++)
          WALK_SUBTREE (TREE_VEC_ELT (args, i));
      }
      break;

    case TYPE_PACK_EXPANSION:
      WALK_SUBTREE (TREE_TYPE (*tp));
      *walk_subtrees_p = 0;
      break;
      
    case EXPR_PACK_EXPANSION:
      WALK_SUBTREE (TREE_OPERAND (*tp, 0));
      *walk_subtrees_p = 0;
      break;

    case CAST_EXPR:
      if (TREE_TYPE (*tp))
        WALK_SUBTREE (TREE_TYPE (*tp));

      {
        int i;
        for (i = 0; i < TREE_CODE_LENGTH (TREE_CODE (*tp)); ++i)
          WALK_SUBTREE (TREE_OPERAND (*tp, i));
      }
      *walk_subtrees_p = 0;
      break;

    case TRAIT_EXPR:
      WALK_SUBTREE (TRAIT_EXPR_TYPE1 (*tp));
      WALK_SUBTREE (TRAIT_EXPR_TYPE2 (*tp));
      *walk_subtrees_p = 0;
      break;

    case DECLTYPE_TYPE:
      WALK_SUBTREE (DECLTYPE_TYPE_EXPR (*tp));
      *walk_subtrees_p = 0;
      break;
 

    default:
      return NULL_TREE;
    }

  /* We didn't find what we were looking for.  */
 out:
  return result;

#undef WALK_SUBTREE
}

/* Like save_expr, but for C++.  */

tree
cp_save_expr (tree expr)
{
  /* There is no reason to create a SAVE_EXPR within a template; if
     needed, we can create the SAVE_EXPR when instantiating the
     template.  Furthermore, the middle-end cannot handle C++-specific
     tree codes.  */
  if (processing_template_decl)
    return expr;
  return save_expr (expr);
}

/* Initialize tree.c.  */

void
init_tree (void)
{
  list_hash_table = htab_create_ggc (31, list_hash, list_hash_eq, NULL);
}

/* Returns the kind of special function that DECL (a FUNCTION_DECL)
   is.  Note that sfk_none is zero, so this function can be used as a
   predicate to test whether or not DECL is a special function.  */

special_function_kind
special_function_p (const_tree decl)
{
  /* Rather than doing all this stuff with magic names, we should
     probably have a field of type `special_function_kind' in
     DECL_LANG_SPECIFIC.  */
  if (DECL_COPY_CONSTRUCTOR_P (decl))
    return sfk_copy_constructor;
  if (DECL_CONSTRUCTOR_P (decl))
    return sfk_constructor;
  if (DECL_OVERLOADED_OPERATOR_P (decl) == NOP_EXPR)
    return sfk_assignment_operator;
  if (DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (decl))
    return sfk_destructor;
  if (DECL_COMPLETE_DESTRUCTOR_P (decl))
    return sfk_complete_destructor;
  if (DECL_BASE_DESTRUCTOR_P (decl))
    return sfk_base_destructor;
  if (DECL_DELETING_DESTRUCTOR_P (decl))
    return sfk_deleting_destructor;
  if (DECL_CONV_FN_P (decl))
    return sfk_conversion;

  return sfk_none;
}

/* Returns nonzero if TYPE is a character type, including wchar_t.  */

int
char_type_p (tree type)
{
  return (same_type_p (type, char_type_node)
          || same_type_p (type, unsigned_char_type_node)
          || same_type_p (type, signed_char_type_node)
          || same_type_p (type, wchar_type_node));
}

/* Returns the kind of linkage associated with the indicated DECL.  Th
   value returned is as specified by the language standard; it is
   independent of implementation details regarding template
   instantiation, etc.  For example, it is possible that a declaration
   to which this function assigns external linkage would not show up
   as a global symbol when you run `nm' on the resulting object file.  */

linkage_kind
decl_linkage (tree decl)
{
  /* This function doesn't attempt to calculate the linkage from first
     principles as given in [basic.link].  Instead, it makes use of
     the fact that we have already set TREE_PUBLIC appropriately, and
     then handles a few special cases.  Ideally, we would calculate
     linkage first, and then transform that into a concrete
     implementation.  */

  /* Things that don't have names have no linkage.  */
  if (!DECL_NAME (decl))
    return lk_none;

  /* Things that are TREE_PUBLIC have external linkage.  */
  if (TREE_PUBLIC (decl))
    return lk_external;

  if (TREE_CODE (decl) == NAMESPACE_DECL)
    return lk_external;

  /* Linkage of a CONST_DECL depends on the linkage of the enumeration
     type.  */
  if (TREE_CODE (decl) == CONST_DECL)
    return decl_linkage (TYPE_NAME (TREE_TYPE (decl)));

  /* Some things that are not TREE_PUBLIC have external linkage, too.
     For example, on targets that don't have weak symbols, we make all
     template instantiations have internal linkage (in the object
     file), but the symbols should still be treated as having external
     linkage from the point of view of the language.  */
  if (TREE_CODE (decl) != TYPE_DECL && DECL_LANG_SPECIFIC (decl)
      && DECL_COMDAT (decl))
    return lk_external;

  /* Things in local scope do not have linkage, if they don't have
     TREE_PUBLIC set.  */
  if (decl_function_context (decl))
    return lk_none;

  /* Members of the anonymous namespace also have TREE_PUBLIC unset, but
     are considered to have external linkage for language purposes.  DECLs
     really meant to have internal linkage have DECL_THIS_STATIC set.  */
  if (TREE_CODE (decl) == TYPE_DECL
      || ((TREE_CODE (decl) == VAR_DECL || TREE_CODE (decl) == FUNCTION_DECL)
          && !DECL_THIS_STATIC (decl)))
    return lk_external;

  /* Everything else has internal linkage.  */
  return lk_internal;
}
\f
/* EXP is an expression that we want to pre-evaluate.  Returns (in
   *INITP) an expression that will perform the pre-evaluation.  The
   value returned by this function is a side-effect free expression
   equivalent to the pre-evaluated expression.  Callers must ensure
   that *INITP is evaluated before EXP.  */

tree
stabilize_expr (tree exp, tree* initp)
{
  tree init_expr;

  if (!TREE_SIDE_EFFECTS (exp))
    init_expr = NULL_TREE;
  else if (!real_lvalue_p (exp)
           || !TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (exp)))
    {
      init_expr = get_target_expr (exp);
      exp = TARGET_EXPR_SLOT (init_expr);
    }
  else
    {
      exp = build_unary_op (ADDR_EXPR, exp, 1);
      init_expr = get_target_expr (exp);
      exp = TARGET_EXPR_SLOT (init_expr);
      exp = build_indirect_ref (exp, 0);
    }
  *initp = init_expr;

  gcc_assert (!TREE_SIDE_EFFECTS (exp));
  return exp;
}

/* Add NEW, an expression whose value we don't care about, after the
   similar expression ORIG.  */

tree
add_stmt_to_compound (tree orig, tree new)
{
  if (!new || !TREE_SIDE_EFFECTS (new))
    return orig;
  if (!orig || !TREE_SIDE_EFFECTS (orig))
    return new;
  return build2 (COMPOUND_EXPR, void_type_node, orig, new);
}

/* Like stabilize_expr, but for a call whose arguments we want to
   pre-evaluate.  CALL is modified in place to use the pre-evaluated
   arguments, while, upon return, *INITP contains an expression to
   compute the arguments.  */

void
stabilize_call (tree call, tree *initp)
{
  tree inits = NULL_TREE;
  int i;
  int nargs = call_expr_nargs (call);

  if (call == error_mark_node)
    return;

  gcc_assert (TREE_CODE (call) == CALL_EXPR);

  for (i = 0; i < nargs; i++)
    {
      tree init;
      CALL_EXPR_ARG (call, i) =
        stabilize_expr (CALL_EXPR_ARG (call, i), &init);
      inits = add_stmt_to_compound (inits, init);
    }

  *initp = inits;
}

/* Like stabilize_expr, but for an AGGR_INIT_EXPR whose arguments we want
   to pre-evaluate.  CALL is modified in place to use the pre-evaluated
   arguments, while, upon return, *INITP contains an expression to
   compute the arguments.  */

void
stabilize_aggr_init (tree call, tree *initp)
{
  tree inits = NULL_TREE;
  int i;
  int nargs = aggr_init_expr_nargs (call);

  if (call == error_mark_node)
    return;

  gcc_assert (TREE_CODE (call) == AGGR_INIT_EXPR);

  for (i = 0; i < nargs; i++)
    {
      tree init;
      AGGR_INIT_EXPR_ARG (call, i) =
        stabilize_expr (AGGR_INIT_EXPR_ARG (call, i), &init);
      inits = add_stmt_to_compound (inits, init);
    }

  *initp = inits;
}

/* Like stabilize_expr, but for an initialization.  

   If the initialization is for an object of class type, this function
   takes care not to introduce additional temporaries.

   Returns TRUE iff the expression was successfully pre-evaluated,
   i.e., if INIT is now side-effect free, except for, possible, a
   single call to a constructor.  */

bool
stabilize_init (tree init, tree *initp)
{
  tree t = init;

  *initp = NULL_TREE;

  if (t == error_mark_node)
    return true;

  if (TREE_CODE (t) == INIT_EXPR
      && TREE_CODE (TREE_OPERAND (t, 1)) != TARGET_EXPR)
    {
      TREE_OPERAND (t, 1) = stabilize_expr (TREE_OPERAND (t, 1), initp);
      return true;
    }

  if (TREE_CODE (t) == INIT_EXPR)
    t = TREE_OPERAND (t, 1);
  if (TREE_CODE (t) == TARGET_EXPR)
    t = TARGET_EXPR_INITIAL (t);
  if (TREE_CODE (t) == COMPOUND_EXPR)
    t = expr_last (t);
  if (TREE_CODE (t) == CONSTRUCTOR
      && EMPTY_CONSTRUCTOR_P (t))
    /* Default-initialization.  */
    return true;

  /* If the initializer is a COND_EXPR, we can't preevaluate
     anything.  */
  if (TREE_CODE (t) == COND_EXPR)
    return false;

  if (TREE_CODE (t) == CALL_EXPR)
    {
      stabilize_call (t, initp);
      return true;
    }

  if (TREE_CODE (t) == AGGR_INIT_EXPR)
    {
      stabilize_aggr_init (t, initp);
      return true;
    }

  /* The initialization is being performed via a bitwise copy -- and
     the item copied may have side effects.  */
  return TREE_SIDE_EFFECTS (init);
}

/* Like "fold", but should be used whenever we might be processing the
   body of a template.  */

tree
fold_if_not_in_template (tree expr)
{
  /* In the body of a template, there is never any need to call
     "fold".  We will call fold later when actually instantiating the
     template.  Integral constant expressions in templates will be
     evaluated via fold_non_dependent_expr, as necessary.  */
  if (processing_template_decl)
    return expr;

  /* Fold C++ front-end specific tree codes.  */
  if (TREE_CODE (expr) == UNARY_PLUS_EXPR)
    return fold_convert (TREE_TYPE (expr), TREE_OPERAND (expr, 0));

  return fold (expr);
}

/* Returns true if a cast to TYPE may appear in an integral constant
   expression.  */

bool
cast_valid_in_integral_constant_expression_p (tree type)
{
  return (INTEGRAL_OR_ENUMERATION_TYPE_P (type)
          || dependent_type_p (type)
          || type == error_mark_node);
}

\f
#if defined ENABLE_TREE_CHECKING && (GCC_VERSION >= 2007)
/* Complain that some language-specific thing hanging off a tree
   node has been accessed improperly.  */

void
lang_check_failed (const char* file, int line, const char* function)
{
  internal_error ("lang_* check: failed in %s, at %s:%d",
                  function, trim_filename (file), line);
}
#endif /* ENABLE_TREE_CHECKING */

#include "gt-cp-tree.h"