PR bootstrap/44048

[pf3gnuchains/gcc-fork.git] / gcc / cp / typeck.c

/* Build expressions with type checking for C++ compiler.
   Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
   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/>.  */


/* This file is part of the C++ front end.
   It contains routines to build C++ expressions given their operands,
   including computing the types of the result, C and C++ specific error
   checks, and some optimization.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "expr.h"
#include "cp-tree.h"
#include "tm_p.h"
#include "flags.h"
#include "output.h"
#include "toplev.h"
#include "diagnostic.h"
#include "intl.h"
#include "target.h"
#include "convert.h"
#include "c-common.h"
#include "params.h"

static tree pfn_from_ptrmemfunc (tree);
static tree delta_from_ptrmemfunc (tree);
static tree convert_for_assignment (tree, tree, const char *, tree, int,
                                    tsubst_flags_t, int);
static tree cp_pointer_int_sum (enum tree_code, tree, tree);
static tree rationalize_conditional_expr (enum tree_code, tree, 
                                          tsubst_flags_t);
static int comp_ptr_ttypes_real (tree, tree, int);
static bool comp_except_types (tree, tree, bool);
static bool comp_array_types (const_tree, const_tree, bool);
static tree pointer_diff (tree, tree, tree);
static tree get_delta_difference (tree, tree, bool, bool);
static void casts_away_constness_r (tree *, tree *);
static bool casts_away_constness (tree, tree);
static void maybe_warn_about_returning_address_of_local (tree);
static tree lookup_destructor (tree, tree, tree);
static void warn_args_num (location_t, tree, bool);
static int convert_arguments (tree, VEC(tree,gc) **, tree, int,
                              tsubst_flags_t);

/* Do `exp = require_complete_type (exp);' to make sure exp
   does not have an incomplete type.  (That includes void types.)
   Returns the error_mark_node if the VALUE does not have
   complete type when this function returns.  */

tree
require_complete_type (tree value)
{
  tree type;

  if (processing_template_decl || value == error_mark_node)
    return value;

  if (TREE_CODE (value) == OVERLOAD)
    type = unknown_type_node;
  else
    type = TREE_TYPE (value);

  if (type == error_mark_node)
    return error_mark_node;

  /* First, detect a valid value with a complete type.  */
  if (COMPLETE_TYPE_P (type))
    return value;

  if (complete_type_or_else (type, value))
    return value;
  else
    return error_mark_node;
}

/* Try to complete TYPE, if it is incomplete.  For example, if TYPE is
   a template instantiation, do the instantiation.  Returns TYPE,
   whether or not it could be completed, unless something goes
   horribly wrong, in which case the error_mark_node is returned.  */

tree
complete_type (tree type)
{
  if (type == NULL_TREE)
    /* Rather than crash, we return something sure to cause an error
       at some point.  */
    return error_mark_node;

  if (type == error_mark_node || COMPLETE_TYPE_P (type))
    ;
  else if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
    {
      tree t = complete_type (TREE_TYPE (type));
      unsigned int needs_constructing, has_nontrivial_dtor;
      if (COMPLETE_TYPE_P (t) && !dependent_type_p (type))
        layout_type (type);
      needs_constructing
        = TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (t));
      has_nontrivial_dtor
        = TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TYPE_MAIN_VARIANT (t));
      for (t = TYPE_MAIN_VARIANT (type); t; t = TYPE_NEXT_VARIANT (t))
        {
          TYPE_NEEDS_CONSTRUCTING (t) = needs_constructing;
          TYPE_HAS_NONTRIVIAL_DESTRUCTOR (t) = has_nontrivial_dtor;
        }
    }
  else if (CLASS_TYPE_P (type) && CLASSTYPE_TEMPLATE_INSTANTIATION (type))
    instantiate_class_template (TYPE_MAIN_VARIANT (type));

  return type;
}

/* Like complete_type, but issue an error if the TYPE cannot be completed.
   VALUE is used for informative diagnostics.
   Returns NULL_TREE if the type cannot be made complete.  */

tree
complete_type_or_else (tree type, tree value)
{
  type = complete_type (type);
  if (type == error_mark_node)
    /* We already issued an error.  */
    return NULL_TREE;
  else if (!COMPLETE_TYPE_P (type))
    {
      cxx_incomplete_type_diagnostic (value, type, DK_ERROR);
      return NULL_TREE;
    }
  else
    return type;
}

/* Return truthvalue of whether type of EXP is instantiated.  */

int
type_unknown_p (const_tree exp)
{
  return (TREE_CODE (exp) == TREE_LIST
          || TREE_TYPE (exp) == unknown_type_node);
}

\f
/* Return the common type of two parameter lists.
   We assume that comptypes has already been done and returned 1;
   if that isn't so, this may crash.

   As an optimization, free the space we allocate if the parameter
   lists are already common.  */

static tree
commonparms (tree p1, tree p2)
{
  tree oldargs = p1, newargs, n;
  int i, len;
  int any_change = 0;

  len = list_length (p1);
  newargs = tree_last (p1);

  if (newargs == void_list_node)
    i = 1;
  else
    {
      i = 0;
      newargs = 0;
    }

  for (; i < len; i++)
    newargs = tree_cons (NULL_TREE, NULL_TREE, newargs);

  n = newargs;

  for (i = 0; p1;
       p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n), i++)
    {
      if (TREE_PURPOSE (p1) && !TREE_PURPOSE (p2))
        {
          TREE_PURPOSE (n) = TREE_PURPOSE (p1);
          any_change = 1;
        }
      else if (! TREE_PURPOSE (p1))
        {
          if (TREE_PURPOSE (p2))
            {
              TREE_PURPOSE (n) = TREE_PURPOSE (p2);
              any_change = 1;
            }
        }
      else
        {
          if (1 != simple_cst_equal (TREE_PURPOSE (p1), TREE_PURPOSE (p2)))
            any_change = 1;
          TREE_PURPOSE (n) = TREE_PURPOSE (p2);
        }
      if (TREE_VALUE (p1) != TREE_VALUE (p2))
        {
          any_change = 1;
          TREE_VALUE (n) = merge_types (TREE_VALUE (p1), TREE_VALUE (p2));
        }
      else
        TREE_VALUE (n) = TREE_VALUE (p1);
    }
  if (! any_change)
    return oldargs;

  return newargs;
}

/* Given a type, perhaps copied for a typedef,
   find the "original" version of it.  */
static tree
original_type (tree t)
{
  int quals = cp_type_quals (t);
  while (t != error_mark_node
         && TYPE_NAME (t) != NULL_TREE)
    {
      tree x = TYPE_NAME (t);
      if (TREE_CODE (x) != TYPE_DECL)
        break;
      x = DECL_ORIGINAL_TYPE (x);
      if (x == NULL_TREE)
        break;
      t = x;
    }
  return cp_build_qualified_type (t, quals);
}

/* Return the common type for two arithmetic types T1 and T2 under the
   usual arithmetic conversions.  The default conversions have already
   been applied, and enumerated types converted to their compatible
   integer types.  */

static tree
cp_common_type (tree t1, tree t2)
{
  enum tree_code code1 = TREE_CODE (t1);
  enum tree_code code2 = TREE_CODE (t2);
  tree attributes;

  /* In what follows, we slightly generalize the rules given in [expr] so
     as to deal with `long long' and `complex'.  First, merge the
     attributes.  */
  attributes = (*targetm.merge_type_attributes) (t1, t2);

  if (SCOPED_ENUM_P (t1) || SCOPED_ENUM_P (t2))
    {
      if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
        return build_type_attribute_variant (t1, attributes);
      else
        return NULL_TREE;
    }

  /* FIXME: Attributes.  */
  gcc_assert (ARITHMETIC_TYPE_P (t1)
              || TREE_CODE (t1) == VECTOR_TYPE
              || UNSCOPED_ENUM_P (t1));
  gcc_assert (ARITHMETIC_TYPE_P (t2)
              || TREE_CODE (t2) == VECTOR_TYPE
              || UNSCOPED_ENUM_P (t2));

  /* If one type is complex, form the common type of the non-complex
     components, then make that complex.  Use T1 or T2 if it is the
     required type.  */
  if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
    {
      tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
      tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
      tree subtype
        = type_after_usual_arithmetic_conversions (subtype1, subtype2);

      if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
        return build_type_attribute_variant (t1, attributes);
      else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
        return build_type_attribute_variant (t2, attributes);
      else
        return build_type_attribute_variant (build_complex_type (subtype),
                                             attributes);
    }

  if (code1 == VECTOR_TYPE)
    {
      /* When we get here we should have two vectors of the same size.
         Just prefer the unsigned one if present.  */
      if (TYPE_UNSIGNED (t1))
        return build_type_attribute_variant (t1, attributes);
      else
        return build_type_attribute_variant (t2, attributes);
    }

  /* If only one is real, use it as the result.  */
  if (code1 == REAL_TYPE && code2 != REAL_TYPE)
    return build_type_attribute_variant (t1, attributes);
  if (code2 == REAL_TYPE && code1 != REAL_TYPE)
    return build_type_attribute_variant (t2, attributes);

  /* Both real or both integers; use the one with greater precision.  */
  if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
    return build_type_attribute_variant (t1, attributes);
  else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
    return build_type_attribute_variant (t2, attributes);

  /* The types are the same; no need to do anything fancy.  */
  if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
    return build_type_attribute_variant (t1, attributes);

  if (code1 != REAL_TYPE)
    {
      /* If one is unsigned long long, then convert the other to unsigned
         long long.  */
      if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_unsigned_type_node)
          || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_unsigned_type_node))
        return build_type_attribute_variant (long_long_unsigned_type_node,
                                             attributes);
      /* If one is a long long, and the other is an unsigned long, and
         long long can represent all the values of an unsigned long, then
         convert to a long long.  Otherwise, convert to an unsigned long
         long.  Otherwise, if either operand is long long, convert the
         other to long long.

         Since we're here, we know the TYPE_PRECISION is the same;
         therefore converting to long long cannot represent all the values
         of an unsigned long, so we choose unsigned long long in that
         case.  */
      if (same_type_p (TYPE_MAIN_VARIANT (t1), long_long_integer_type_node)
          || same_type_p (TYPE_MAIN_VARIANT (t2), long_long_integer_type_node))
        {
          tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
                    ? long_long_unsigned_type_node
                    : long_long_integer_type_node);
          return build_type_attribute_variant (t, attributes);
        }

      /* Go through the same procedure, but for longs.  */
      if (same_type_p (TYPE_MAIN_VARIANT (t1), long_unsigned_type_node)
          || same_type_p (TYPE_MAIN_VARIANT (t2), long_unsigned_type_node))
        return build_type_attribute_variant (long_unsigned_type_node,
                                             attributes);
      if (same_type_p (TYPE_MAIN_VARIANT (t1), long_integer_type_node)
          || same_type_p (TYPE_MAIN_VARIANT (t2), long_integer_type_node))
        {
          tree t = ((TYPE_UNSIGNED (t1) || TYPE_UNSIGNED (t2))
                    ? long_unsigned_type_node : long_integer_type_node);
          return build_type_attribute_variant (t, attributes);
        }
      /* Otherwise prefer the unsigned one.  */
      if (TYPE_UNSIGNED (t1))
        return build_type_attribute_variant (t1, attributes);
      else
        return build_type_attribute_variant (t2, attributes);
    }
  else
    {
      if (same_type_p (TYPE_MAIN_VARIANT (t1), long_double_type_node)
          || same_type_p (TYPE_MAIN_VARIANT (t2), long_double_type_node))
        return build_type_attribute_variant (long_double_type_node,
                                             attributes);
      if (same_type_p (TYPE_MAIN_VARIANT (t1), double_type_node)
          || same_type_p (TYPE_MAIN_VARIANT (t2), double_type_node))
        return build_type_attribute_variant (double_type_node,
                                             attributes);
      if (same_type_p (TYPE_MAIN_VARIANT (t1), float_type_node)
          || same_type_p (TYPE_MAIN_VARIANT (t2), float_type_node))
        return build_type_attribute_variant (float_type_node,
                                             attributes);

      /* Two floating-point types whose TYPE_MAIN_VARIANTs are none of
         the standard C++ floating-point types.  Logic earlier in this
         function has already eliminated the possibility that
         TYPE_PRECISION (t2) != TYPE_PRECISION (t1), so there's no
         compelling reason to choose one or the other.  */
      return build_type_attribute_variant (t1, attributes);
    }
}

/* T1 and T2 are arithmetic or enumeration types.  Return the type
   that will result from the "usual arithmetic conversions" on T1 and
   T2 as described in [expr].  */

tree
type_after_usual_arithmetic_conversions (tree t1, tree t2)
{
  gcc_assert (ARITHMETIC_TYPE_P (t1)
              || TREE_CODE (t1) == VECTOR_TYPE
              || UNSCOPED_ENUM_P (t1));
  gcc_assert (ARITHMETIC_TYPE_P (t2)
              || TREE_CODE (t2) == VECTOR_TYPE
              || UNSCOPED_ENUM_P (t2));

  /* Perform the integral promotions.  We do not promote real types here.  */
  if (INTEGRAL_OR_ENUMERATION_TYPE_P (t1)
      && INTEGRAL_OR_ENUMERATION_TYPE_P (t2))
    {
      t1 = type_promotes_to (t1);
      t2 = type_promotes_to (t2);
    }

  return cp_common_type (t1, t2);
}

/* Subroutine of composite_pointer_type to implement the recursive
   case.  See that function for documentation of the parameters.  */

static tree
composite_pointer_type_r (tree t1, tree t2, 
                          composite_pointer_operation operation,
                          tsubst_flags_t complain)
{
  tree pointee1;
  tree pointee2;
  tree result_type;
  tree attributes;

  /* Determine the types pointed to by T1 and T2.  */
  if (TREE_CODE (t1) == POINTER_TYPE)
    {
      pointee1 = TREE_TYPE (t1);
      pointee2 = TREE_TYPE (t2);
    }
  else
    {
      pointee1 = TYPE_PTRMEM_POINTED_TO_TYPE (t1);
      pointee2 = TYPE_PTRMEM_POINTED_TO_TYPE (t2);
    }

  /* [expr.rel]

     Otherwise, the composite pointer type is a pointer type
     similar (_conv.qual_) to the type of one of the operands,
     with a cv-qualification signature (_conv.qual_) that is the
     union of the cv-qualification signatures of the operand
     types.  */
  if (same_type_ignoring_top_level_qualifiers_p (pointee1, pointee2))
    result_type = pointee1;
  else if ((TREE_CODE (pointee1) == POINTER_TYPE
            && TREE_CODE (pointee2) == POINTER_TYPE)
           || (TYPE_PTR_TO_MEMBER_P (pointee1)
               && TYPE_PTR_TO_MEMBER_P (pointee2)))
    result_type = composite_pointer_type_r (pointee1, pointee2, operation,
                                            complain);
  else
    {
      if (complain & tf_error)
        {
          switch (operation)
            {
            case CPO_COMPARISON:
              permerror (input_location, "comparison between "
                         "distinct pointer types %qT and %qT lacks a cast",
                         t1, t2);
              break;
            case CPO_CONVERSION:
              permerror (input_location, "conversion between "
                         "distinct pointer types %qT and %qT lacks a cast",
                         t1, t2);
              break;
            case CPO_CONDITIONAL_EXPR:
              permerror (input_location, "conditional expression between "
                         "distinct pointer types %qT and %qT lacks a cast",
                         t1, t2);
              break;
            default:
              gcc_unreachable ();
            }
        }
      result_type = void_type_node;
    }
  result_type = cp_build_qualified_type (result_type,
                                         (cp_type_quals (pointee1)
                                          | cp_type_quals (pointee2)));
  /* If the original types were pointers to members, so is the
     result.  */
  if (TYPE_PTR_TO_MEMBER_P (t1))
    {
      if (!same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
                        TYPE_PTRMEM_CLASS_TYPE (t2))
          && (complain & tf_error))
        {
          switch (operation)
            {
            case CPO_COMPARISON:
              permerror (input_location, "comparison between "
                         "distinct pointer types %qT and %qT lacks a cast", 
                         t1, t2);
              break;
            case CPO_CONVERSION:
              permerror (input_location, "conversion between "
                         "distinct pointer types %qT and %qT lacks a cast",
                         t1, t2);
              break;
            case CPO_CONDITIONAL_EXPR:
              permerror (input_location, "conditional expression between "
                         "distinct pointer types %qT and %qT lacks a cast",
                         t1, t2);
              break;
            default:
              gcc_unreachable ();
            }
        }
      result_type = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
                                       result_type);
    }
  else
    result_type = build_pointer_type (result_type);

  /* Merge the attributes.  */
  attributes = (*targetm.merge_type_attributes) (t1, t2);
  return build_type_attribute_variant (result_type, attributes);
}

/* Return the composite pointer type (see [expr.rel]) for T1 and T2.
   ARG1 and ARG2 are the values with those types.  The OPERATION is to
   describe the operation between the pointer types,
   in case an error occurs.

   This routine also implements the computation of a common type for
   pointers-to-members as per [expr.eq].  */

tree
composite_pointer_type (tree t1, tree t2, tree arg1, tree arg2,
                        composite_pointer_operation operation, 
                        tsubst_flags_t complain)
{
  tree class1;
  tree class2;

  /* [expr.rel]

     If one operand is a null pointer constant, the composite pointer
     type is the type of the other operand.  */
  if (null_ptr_cst_p (arg1))
    return t2;
  if (null_ptr_cst_p (arg2))
    return t1;

  /* We have:

       [expr.rel]

       If one of the operands has type "pointer to cv1 void*", then
       the other has type "pointer to cv2T", and the composite pointer
       type is "pointer to cv12 void", where cv12 is the union of cv1
       and cv2.

    If either type is a pointer to void, make sure it is T1.  */
  if (TREE_CODE (t2) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t2)))
    {
      tree t;
      t = t1;
      t1 = t2;
      t2 = t;
    }

  /* Now, if T1 is a pointer to void, merge the qualifiers.  */
  if (TREE_CODE (t1) == POINTER_TYPE && VOID_TYPE_P (TREE_TYPE (t1)))
    {
      tree attributes;
      tree result_type;

      if (TYPE_PTRFN_P (t2) && (complain & tf_error))
        {
          switch (operation)
              {
              case CPO_COMPARISON:
                pedwarn (input_location, OPT_pedantic, 
                         "ISO C++ forbids comparison between "
                         "pointer of type %<void *%> and pointer-to-function");
                break;
              case CPO_CONVERSION:
                pedwarn (input_location, OPT_pedantic,
                         "ISO C++ forbids conversion between "
                         "pointer of type %<void *%> and pointer-to-function");
                break;
              case CPO_CONDITIONAL_EXPR:
                pedwarn (input_location, OPT_pedantic,
                         "ISO C++ forbids conditional expression between "
                         "pointer of type %<void *%> and pointer-to-function");
                break;
              default:
                gcc_unreachable ();
              }
        }
      result_type
        = cp_build_qualified_type (void_type_node,
                                   (cp_type_quals (TREE_TYPE (t1))
                                    | cp_type_quals (TREE_TYPE (t2))));
      result_type = build_pointer_type (result_type);
      /* Merge the attributes.  */
      attributes = (*targetm.merge_type_attributes) (t1, t2);
      return build_type_attribute_variant (result_type, attributes);
    }

  if (c_dialect_objc () && TREE_CODE (t1) == POINTER_TYPE
      && TREE_CODE (t2) == POINTER_TYPE)
    {
      if (objc_compare_types (t1, t2, -3, NULL_TREE))
        return t1;
    }

  /* [expr.eq] permits the application of a pointer conversion to
     bring the pointers to a common type.  */
  if (TREE_CODE (t1) == POINTER_TYPE && TREE_CODE (t2) == POINTER_TYPE
      && CLASS_TYPE_P (TREE_TYPE (t1))
      && CLASS_TYPE_P (TREE_TYPE (t2))
      && !same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (t1),
                                                     TREE_TYPE (t2)))
    {
      class1 = TREE_TYPE (t1);
      class2 = TREE_TYPE (t2);

      if (DERIVED_FROM_P (class1, class2))
        t2 = (build_pointer_type
              (cp_build_qualified_type (class1, TYPE_QUALS (class2))));
      else if (DERIVED_FROM_P (class2, class1))
        t1 = (build_pointer_type
              (cp_build_qualified_type (class2, TYPE_QUALS (class1))));
      else
        {
          if (complain & tf_error)
            switch (operation)
              {
              case CPO_COMPARISON:
                error ("comparison between distinct "
                       "pointer types %qT and %qT lacks a cast", t1, t2);
                break;
              case CPO_CONVERSION:
                error ("conversion between distinct "
                       "pointer types %qT and %qT lacks a cast", t1, t2);
                break;
              case CPO_CONDITIONAL_EXPR:
                error ("conditional expression between distinct "
                       "pointer types %qT and %qT lacks a cast", t1, t2);
                break;
              default:
                gcc_unreachable ();
              }
          return error_mark_node;
        }
    }
  /* [expr.eq] permits the application of a pointer-to-member
     conversion to change the class type of one of the types.  */
  else if (TYPE_PTR_TO_MEMBER_P (t1)
           && !same_type_p (TYPE_PTRMEM_CLASS_TYPE (t1),
                            TYPE_PTRMEM_CLASS_TYPE (t2)))
    {
      class1 = TYPE_PTRMEM_CLASS_TYPE (t1);
      class2 = TYPE_PTRMEM_CLASS_TYPE (t2);

      if (DERIVED_FROM_P (class1, class2))
        t1 = build_ptrmem_type (class2, TYPE_PTRMEM_POINTED_TO_TYPE (t1));
      else if (DERIVED_FROM_P (class2, class1))
        t2 = build_ptrmem_type (class1, TYPE_PTRMEM_POINTED_TO_TYPE (t2));
      else
        {
          if (complain & tf_error)
            switch (operation)
              {
              case CPO_COMPARISON:
                error ("comparison between distinct "
                       "pointer-to-member types %qT and %qT lacks a cast",
                       t1, t2);
                break;
              case CPO_CONVERSION:
                error ("conversion between distinct "
                       "pointer-to-member types %qT and %qT lacks a cast",
                       t1, t2);
                break;
              case CPO_CONDITIONAL_EXPR:
                error ("conditional expression between distinct "
                       "pointer-to-member types %qT and %qT lacks a cast",
                       t1, t2);
                break;
              default:
                gcc_unreachable ();
              }
          return error_mark_node;
        }
    }

  return composite_pointer_type_r (t1, t2, operation, complain);
}

/* Return the merged type of two types.
   We assume that comptypes has already been done and returned 1;
   if that isn't so, this may crash.

   This just combines attributes and default arguments; any other
   differences would cause the two types to compare unalike.  */

tree
merge_types (tree t1, tree t2)
{
  enum tree_code code1;
  enum tree_code code2;
  tree attributes;

  /* Save time if the two types are the same.  */
  if (t1 == t2)
    return t1;
  if (original_type (t1) == original_type (t2))
    return t1;

  /* If one type is nonsense, use the other.  */
  if (t1 == error_mark_node)
    return t2;
  if (t2 == error_mark_node)
    return t1;

  /* Merge the attributes.  */
  attributes = (*targetm.merge_type_attributes) (t1, t2);

  if (TYPE_PTRMEMFUNC_P (t1))
    t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
  if (TYPE_PTRMEMFUNC_P (t2))
    t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);

  code1 = TREE_CODE (t1);
  code2 = TREE_CODE (t2);
  if (code1 != code2)
    {
      gcc_assert (code1 == TYPENAME_TYPE || code2 == TYPENAME_TYPE);
      if (code1 == TYPENAME_TYPE)
        {
          t1 = resolve_typename_type (t1, /*only_current_p=*/true);
          code1 = TREE_CODE (t1);
        }
      else
        {
          t2 = resolve_typename_type (t2, /*only_current_p=*/true);
          code2 = TREE_CODE (t2);
        }
    }

  switch (code1)
    {
    case POINTER_TYPE:
    case REFERENCE_TYPE:
      /* For two pointers, do this recursively on the target type.  */
      {
        tree target = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
        int quals = cp_type_quals (t1);

        if (code1 == POINTER_TYPE)
          t1 = build_pointer_type (target);
        else
          t1 = cp_build_reference_type (target, TYPE_REF_IS_RVALUE (t1));
        t1 = build_type_attribute_variant (t1, attributes);
        t1 = cp_build_qualified_type (t1, quals);

        if (TREE_CODE (target) == METHOD_TYPE)
          t1 = build_ptrmemfunc_type (t1);

        return t1;
      }

    case OFFSET_TYPE:
      {
        int quals;
        tree pointee;
        quals = cp_type_quals (t1);
        pointee = merge_types (TYPE_PTRMEM_POINTED_TO_TYPE (t1),
                               TYPE_PTRMEM_POINTED_TO_TYPE (t2));
        t1 = build_ptrmem_type (TYPE_PTRMEM_CLASS_TYPE (t1),
                                pointee);
        t1 = cp_build_qualified_type (t1, quals);
        break;
      }

    case ARRAY_TYPE:
      {
        tree elt = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
        /* Save space: see if the result is identical to one of the args.  */
        if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
          return build_type_attribute_variant (t1, attributes);
        if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
          return build_type_attribute_variant (t2, attributes);
        /* Merge the element types, and have a size if either arg has one.  */
        t1 = build_cplus_array_type
          (elt, TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
        break;
      }

    case FUNCTION_TYPE:
      /* Function types: prefer the one that specified arg types.
         If both do, merge the arg types.  Also merge the return types.  */
      {
        tree valtype = merge_types (TREE_TYPE (t1), TREE_TYPE (t2));
        tree p1 = TYPE_ARG_TYPES (t1);
        tree p2 = TYPE_ARG_TYPES (t2);
        tree rval, raises;

        /* Save space: see if the result is identical to one of the args.  */
        if (valtype == TREE_TYPE (t1) && ! p2)
          return cp_build_type_attribute_variant (t1, attributes);
        if (valtype == TREE_TYPE (t2) && ! p1)
          return cp_build_type_attribute_variant (t2, attributes);

        /* Simple way if one arg fails to specify argument types.  */
        if (p1 == NULL_TREE || TREE_VALUE (p1) == void_type_node)
          {
            rval = build_function_type (valtype, p2);
            if ((raises = TYPE_RAISES_EXCEPTIONS (t2)))
              rval = build_exception_variant (rval, raises);
            return cp_build_type_attribute_variant (rval, attributes);
          }
        raises = TYPE_RAISES_EXCEPTIONS (t1);
        if (p2 == NULL_TREE || TREE_VALUE (p2) == void_type_node)
          {
            rval = build_function_type (valtype, p1);
            if (raises)
              rval = build_exception_variant (rval, raises);
            return cp_build_type_attribute_variant (rval, attributes);
          }

        rval = build_function_type (valtype, commonparms (p1, p2));
        t1 = build_exception_variant (rval, raises);
        break;
      }

    case METHOD_TYPE:
      {
        /* Get this value the long way, since TYPE_METHOD_BASETYPE
           is just the main variant of this.  */
        tree basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t2)));
        tree raises = TYPE_RAISES_EXCEPTIONS (t1);
        tree t3;

        /* If this was a member function type, get back to the
           original type of type member function (i.e., without
           the class instance variable up front.  */
        t1 = build_function_type (TREE_TYPE (t1),
                                  TREE_CHAIN (TYPE_ARG_TYPES (t1)));
        t2 = build_function_type (TREE_TYPE (t2),
                                  TREE_CHAIN (TYPE_ARG_TYPES (t2)));
        t3 = merge_types (t1, t2);
        t3 = build_method_type_directly (basetype, TREE_TYPE (t3),
                                         TYPE_ARG_TYPES (t3));
        t1 = build_exception_variant (t3, raises);
        break;
      }

    case TYPENAME_TYPE:
      /* There is no need to merge attributes into a TYPENAME_TYPE.
         When the type is instantiated it will have whatever
         attributes result from the instantiation.  */
      return t1;

    default:;
    }

  if (attribute_list_equal (TYPE_ATTRIBUTES (t1), attributes))
    return t1;
  else if (attribute_list_equal (TYPE_ATTRIBUTES (t2), attributes))
    return t2;
  else
    return cp_build_type_attribute_variant (t1, attributes);
}

/* Return the ARRAY_TYPE type without its domain.  */

tree
strip_array_domain (tree type)
{
  tree t2;
  gcc_assert (TREE_CODE (type) == ARRAY_TYPE);
  if (TYPE_DOMAIN (type) == NULL_TREE)
    return type;
  t2 = build_cplus_array_type (TREE_TYPE (type), NULL_TREE);
  return cp_build_type_attribute_variant (t2, TYPE_ATTRIBUTES (type));
}

/* Wrapper around cp_common_type that is used by c-common.c and other
   front end optimizations that remove promotions.  

   Return the common type for two arithmetic types T1 and T2 under the
   usual arithmetic conversions.  The default conversions have already
   been applied, and enumerated types converted to their compatible
   integer types.  */

tree
common_type (tree t1, tree t2)
{
  /* If one type is nonsense, use the other  */
  if (t1 == error_mark_node)
    return t2;
  if (t2 == error_mark_node)
    return t1;

  return cp_common_type (t1, t2);
}

/* Return the common type of two pointer types T1 and T2.  This is the
   type for the result of most arithmetic operations if the operands
   have the given two types.
 
   We assume that comp_target_types has already been done and returned
   nonzero; if that isn't so, this may crash.  */

tree
common_pointer_type (tree t1, tree t2)
{
  gcc_assert ((TYPE_PTR_P (t1) && TYPE_PTR_P (t2))
              || (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
              || (TYPE_PTRMEMFUNC_P (t1) && TYPE_PTRMEMFUNC_P (t2)));

  return composite_pointer_type (t1, t2, error_mark_node, error_mark_node,
                                 CPO_CONVERSION, tf_warning_or_error);
}
\f
/* Compare two exception specifier types for exactness or subsetness, if
   allowed. Returns false for mismatch, true for match (same, or
   derived and !exact).

   [except.spec] "If a class X ... objects of class X or any class publicly
   and unambiguously derived from X. Similarly, if a pointer type Y * ...
   exceptions of type Y * or that are pointers to any type publicly and
   unambiguously derived from Y. Otherwise a function only allows exceptions
   that have the same type ..."
   This does not mention cv qualifiers and is different to what throw
   [except.throw] and catch [except.catch] will do. They will ignore the
   top level cv qualifiers, and allow qualifiers in the pointer to class
   example.

   We implement the letter of the standard.  */

static bool
comp_except_types (tree a, tree b, bool exact)
{
  if (same_type_p (a, b))
    return true;
  else if (!exact)
    {
      if (cp_type_quals (a) || cp_type_quals (b))
        return false;

      if (TREE_CODE (a) == POINTER_TYPE
          && TREE_CODE (b) == POINTER_TYPE)
        {
          a = TREE_TYPE (a);
          b = TREE_TYPE (b);
          if (cp_type_quals (a) || cp_type_quals (b))
            return false;
        }

      if (TREE_CODE (a) != RECORD_TYPE
          || TREE_CODE (b) != RECORD_TYPE)
        return false;

      if (PUBLICLY_UNIQUELY_DERIVED_P (a, b))
        return true;
    }
  return false;
}

/* Return true if TYPE1 and TYPE2 are equivalent exception specifiers.
   If EXACT is false, T2 can be stricter than T1 (according to 15.4/7),
   otherwise it must be exact. Exception lists are unordered, but
   we've already filtered out duplicates. Most lists will be in order,
   we should try to make use of that.  */

bool
comp_except_specs (const_tree t1, const_tree t2, bool exact)
{
  const_tree probe;
  const_tree base;
  int  length = 0;

  if (t1 == t2)
    return true;

  if (t1 == NULL_TREE)                     /* T1 is ...  */
    return t2 == NULL_TREE || !exact;
  if (!TREE_VALUE (t1))                    /* t1 is EMPTY */
    return t2 != NULL_TREE && !TREE_VALUE (t2);
  if (t2 == NULL_TREE)                     /* T2 is ...  */
    return false;
  if (TREE_VALUE (t1) && !TREE_VALUE (t2)) /* T2 is EMPTY, T1 is not */
    return !exact;

  /* Neither set is ... or EMPTY, make sure each part of T2 is in T1.
     Count how many we find, to determine exactness. For exact matching and
     ordered T1, T2, this is an O(n) operation, otherwise its worst case is
     O(nm).  */
  for (base = t1; t2 != NULL_TREE; t2 = TREE_CHAIN (t2))
    {
      for (probe = base; probe != NULL_TREE; probe = TREE_CHAIN (probe))
        {
          tree a = TREE_VALUE (probe);
          tree b = TREE_VALUE (t2);

          if (comp_except_types (a, b, exact))
            {
              if (probe == base && exact)
                base = TREE_CHAIN (probe);
              length++;
              break;
            }
        }
      if (probe == NULL_TREE)
        return false;
    }
  return !exact || base == NULL_TREE || length == list_length (t1);
}

/* Compare the array types T1 and T2.  ALLOW_REDECLARATION is true if
   [] can match [size].  */

static bool
comp_array_types (const_tree t1, const_tree t2, bool allow_redeclaration)
{
  tree d1;
  tree d2;
  tree max1, max2;

  if (t1 == t2)
    return true;

  /* The type of the array elements must be the same.  */
  if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
    return false;

  d1 = TYPE_DOMAIN (t1);
  d2 = TYPE_DOMAIN (t2);

  if (d1 == d2)
    return true;

  /* If one of the arrays is dimensionless, and the other has a
     dimension, they are of different types.  However, it is valid to
     write:

       extern int a[];
       int a[3];

     by [basic.link]:

       declarations for an array object can specify
       array types that differ by the presence or absence of a major
       array bound (_dcl.array_).  */
  if (!d1 || !d2)
    return allow_redeclaration;

  /* Check that the dimensions are the same.  */

  if (!cp_tree_equal (TYPE_MIN_VALUE (d1), TYPE_MIN_VALUE (d2)))
    return false;
  max1 = TYPE_MAX_VALUE (d1);
  max2 = TYPE_MAX_VALUE (d2);
  if (processing_template_decl && !abi_version_at_least (2)
      && !value_dependent_expression_p (max1)
      && !value_dependent_expression_p (max2))
    {
      /* With abi-1 we do not fold non-dependent array bounds, (and
         consequently mangle them incorrectly).  We must therefore
         fold them here, to verify the domains have the same
         value.  */
      max1 = fold (max1);
      max2 = fold (max2);
    }

  if (!cp_tree_equal (max1, max2))
    return false;

  return true;
}

/* Compare the relative position of T1 and T2 into their respective
   template parameter list.
   T1 and T2 must be template parameter types.
   Return TRUE if T1 and T2 have the same position, FALSE otherwise.  */

static bool
comp_template_parms_position (tree t1, tree t2)
{
  gcc_assert (t1 && t2
              && TREE_CODE (t1) == TREE_CODE (t2)
              && (TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM
                  || TREE_CODE (t1) == TEMPLATE_TEMPLATE_PARM
                  || TREE_CODE (t1) == TEMPLATE_TYPE_PARM));

      if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
          || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2)
          || (TEMPLATE_TYPE_PARAMETER_PACK (t1) 
              != TEMPLATE_TYPE_PARAMETER_PACK (t2)))
        return false;

      return true;
}

/* Subroutine of incompatible_dependent_types_p.
   Return the template parameter of the dependent type T.
   If T is a typedef, return the template parameters of
   the _decl_ of the typedef. T must be a dependent type.  */

static tree
get_template_parms_of_dependent_type (tree t)
{
  tree tinfo = NULL_TREE, tparms = NULL_TREE;

  /* First, try the obvious case of getting the
     template info from T itself.  */
  if ((tinfo = get_template_info (t)))
    ;
  else if (TREE_CODE (t) == TEMPLATE_TYPE_PARM)
    return TEMPLATE_TYPE_PARM_SIBLING_PARMS (t);
  else if (typedef_variant_p (t)
           && !NAMESPACE_SCOPE_P (TYPE_NAME (t)))
    tinfo = get_template_info (DECL_CONTEXT (TYPE_NAME (t)));
  /* If T is a TYPENAME_TYPE which context is a template type
     parameter, get the template parameters from that context.  */
  else if (TYPE_CONTEXT (t)
           && TREE_CODE (TYPE_CONTEXT (t)) == TEMPLATE_TYPE_PARM)
   return TEMPLATE_TYPE_PARM_SIBLING_PARMS (TYPE_CONTEXT (t));
  else if (TYPE_CONTEXT (t)
           && !NAMESPACE_SCOPE_P (t))
    tinfo = get_template_info (TYPE_CONTEXT (t));

  if (tinfo)
    tparms = DECL_TEMPLATE_PARMS (TI_TEMPLATE (tinfo));

  return tparms;
}

/* Subroutine of structural_comptypes.
   Compare the dependent types T1 and T2.
   Return TRUE if we are sure they can't be equal, FALSE otherwise.
   The whole point of this function is to support cases where either T1 or
   T2 is a typedef. In those cases, we need to compare the template parameters
   of the _decl_ of the typedef. If those don't match then we know T1
   and T2 cannot be equal.  */

static bool
incompatible_dependent_types_p (tree t1, tree t2)
{
  tree tparms1 = NULL_TREE, tparms2 = NULL_TREE;
  bool t1_typedef_variant_p, t2_typedef_variant_p;

  if (!uses_template_parms (t1) || !uses_template_parms (t2))
    return false;

  if (TREE_CODE (t1) == TEMPLATE_TYPE_PARM)
    {
      /* If T1 and T2 don't have the same relative position in their
         template parameters set, they can't be equal.  */
      if (!comp_template_parms_position (t1, t2))
        return true;
    }

  t1_typedef_variant_p = typedef_variant_p (t1);
  t2_typedef_variant_p = typedef_variant_p (t2);

  /* Either T1 or T2 must be a typedef.  */
  if (!t1_typedef_variant_p && !t2_typedef_variant_p)
    return false;

  if (!t1_typedef_variant_p || !t2_typedef_variant_p)
    /* Either T1 or T2 is not a typedef so we cannot compare the
       the template parms of the typedefs of T1 and T2.
       At this point, if the main variant type of T1 and T2 are equal
       it means the two types can't be incompatible, from the perspective
       of this function.  */
    if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
      return false;

  /* So if we reach this point, it means either T1 or T2 is a typedef variant.
     Let's compare their template parameters.  */

  tparms1 = get_template_parms_of_dependent_type (t1);
  tparms2 = get_template_parms_of_dependent_type (t2);

  /* If T2 is a template type parm and if we could not get the template
     parms it belongs to, that means we have not finished parsing the
     full set of template parameters of the template declaration it
     belongs to yet. If we could get the template parms T1 belongs to,
     that mostly means T1 and T2 belongs to templates that are
     different and incompatible.  */
  if (TREE_CODE (t1) == TEMPLATE_TYPE_PARM
      && (tparms1 == NULL_TREE || tparms2 == NULL_TREE)
      && tparms1 != tparms2)
    return true;

  if (tparms1 == NULL_TREE
      || tparms2 == NULL_TREE
      || tparms1 == tparms2)
    return false;

  /* And now compare the mighty template parms!  */
  return !comp_template_parms (tparms1, tparms2);
}

/* Subroutine in comptypes.  */

static bool
structural_comptypes (tree t1, tree t2, int strict)
{
  if (t1 == t2)
    return true;

  /* Suppress errors caused by previously reported errors.  */
  if (t1 == error_mark_node || t2 == error_mark_node)
    return false;

  gcc_assert (TYPE_P (t1) && TYPE_P (t2));

  /* TYPENAME_TYPEs should be resolved if the qualifying scope is the
     current instantiation.  */
  if (TREE_CODE (t1) == TYPENAME_TYPE)
    t1 = resolve_typename_type (t1, /*only_current_p=*/true);

  if (TREE_CODE (t2) == TYPENAME_TYPE)
    t2 = resolve_typename_type (t2, /*only_current_p=*/true);

  if (TYPE_PTRMEMFUNC_P (t1))
    t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
  if (TYPE_PTRMEMFUNC_P (t2))
    t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);

  /* Different classes of types can't be compatible.  */
  if (TREE_CODE (t1) != TREE_CODE (t2))
    return false;

  /* Qualifiers must match.  For array types, we will check when we
     recur on the array element types.  */
  if (TREE_CODE (t1) != ARRAY_TYPE
      && TYPE_QUALS (t1) != TYPE_QUALS (t2))
    return false;
  if (TYPE_FOR_JAVA (t1) != TYPE_FOR_JAVA (t2))
    return false;

  /* If T1 and T2 are dependent typedefs then check upfront that
     the template parameters of their typedef DECLs match before
     going down checking their subtypes.  */
  if (incompatible_dependent_types_p (t1, t2))
    return false;

  /* Allow for two different type nodes which have essentially the same
     definition.  Note that we already checked for equality of the type
     qualifiers (just above).  */

  if (TREE_CODE (t1) != ARRAY_TYPE
      && TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
    return true;


  /* Compare the types.  Break out if they could be the same.  */
  switch (TREE_CODE (t1))
    {
    case VOID_TYPE:
    case BOOLEAN_TYPE:
      /* All void and bool types are the same.  */
      break;

    case INTEGER_TYPE:
    case FIXED_POINT_TYPE:
    case REAL_TYPE:
      /* With these nodes, we can't determine type equivalence by
         looking at what is stored in the nodes themselves, because
         two nodes might have different TYPE_MAIN_VARIANTs but still
         represent the same type.  For example, wchar_t and int could
         have the same properties (TYPE_PRECISION, TYPE_MIN_VALUE,
         TYPE_MAX_VALUE, etc.), but have different TYPE_MAIN_VARIANTs
         and are distinct types. On the other hand, int and the
         following typedef

           typedef int INT __attribute((may_alias));

         have identical properties, different TYPE_MAIN_VARIANTs, but
         represent the same type.  The canonical type system keeps
         track of equivalence in this case, so we fall back on it.  */
      return TYPE_CANONICAL (t1) == TYPE_CANONICAL (t2);

    case TEMPLATE_TEMPLATE_PARM:
    case BOUND_TEMPLATE_TEMPLATE_PARM:
      if (!comp_template_parms_position (t1, t2))
        return false;
      if (!comp_template_parms
          (DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t1)),
           DECL_TEMPLATE_PARMS (TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (t2))))
        return false;
      if (TREE_CODE (t1) == TEMPLATE_TEMPLATE_PARM)
        break;
      /* Don't check inheritance.  */
      strict = COMPARE_STRICT;
      /* Fall through.  */

    case RECORD_TYPE:
    case UNION_TYPE:
      if (TYPE_TEMPLATE_INFO (t1) && TYPE_TEMPLATE_INFO (t2)
          && (TYPE_TI_TEMPLATE (t1) == TYPE_TI_TEMPLATE (t2)
              || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM)
          && comp_template_args (TYPE_TI_ARGS (t1), TYPE_TI_ARGS (t2)))
        break;

      if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
        break;
      else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1))
        break;

      return false;

    case OFFSET_TYPE:
      if (!comptypes (TYPE_OFFSET_BASETYPE (t1), TYPE_OFFSET_BASETYPE (t2),
                      strict & ~COMPARE_REDECLARATION))
        return false;
      if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
        return false;
      break;

    case REFERENCE_TYPE:
      if (TYPE_REF_IS_RVALUE (t1) != TYPE_REF_IS_RVALUE (t2))
        return false;
      /* fall through to checks for pointer types */

    case POINTER_TYPE:
      if (TYPE_MODE (t1) != TYPE_MODE (t2)
          || TYPE_REF_CAN_ALIAS_ALL (t1) != TYPE_REF_CAN_ALIAS_ALL (t2)
          || !same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
        return false;
      break;

    case METHOD_TYPE:
    case FUNCTION_TYPE:
      if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
        return false;
      if (!compparms (TYPE_ARG_TYPES (t1), TYPE_ARG_TYPES (t2)))
        return false;
      break;

    case ARRAY_TYPE:
      /* Target types must match incl. qualifiers.  */
      if (!comp_array_types (t1, t2, !!(strict & COMPARE_REDECLARATION)))
        return false;
      break;

    case TEMPLATE_TYPE_PARM:
      /* If incompatible_dependent_types_p called earlier didn't decide
         T1 and T2 were different, they might be equal.  */
      break;

    case TYPENAME_TYPE:
      if (!cp_tree_equal (TYPENAME_TYPE_FULLNAME (t1),
                          TYPENAME_TYPE_FULLNAME (t2)))
        return false;
      if (!same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2)))
        return false;
      break;

    case UNBOUND_CLASS_TEMPLATE:
      if (!cp_tree_equal (TYPE_IDENTIFIER (t1), TYPE_IDENTIFIER (t2)))
        return false;
      if (!same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2)))
        return false;
      break;

    case COMPLEX_TYPE:
      if (!same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
        return false;
      break;

    case VECTOR_TYPE:
      if (TYPE_VECTOR_SUBPARTS (t1) != TYPE_VECTOR_SUBPARTS (t2)
          || !same_type_p (TREE_TYPE (t1), TREE_TYPE (t2)))
        return false;
      break;

    case TYPE_PACK_EXPANSION:
      return same_type_p (PACK_EXPANSION_PATTERN (t1), 
                          PACK_EXPANSION_PATTERN (t2));

    case DECLTYPE_TYPE:
      if (DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t1)
          != DECLTYPE_TYPE_ID_EXPR_OR_MEMBER_ACCESS_P (t2)
          || (DECLTYPE_FOR_LAMBDA_CAPTURE (t1)
              != DECLTYPE_FOR_LAMBDA_CAPTURE (t2))
          || (DECLTYPE_FOR_LAMBDA_RETURN (t1)
              != DECLTYPE_FOR_LAMBDA_RETURN (t2))
          || !cp_tree_equal (DECLTYPE_TYPE_EXPR (t1), 
                             DECLTYPE_TYPE_EXPR (t2)))
        return false;
      break;

    default:
      return false;
    }

  /* If we get here, we know that from a target independent POV the
     types are the same.  Make sure the target attributes are also
     the same.  */
  return targetm.comp_type_attributes (t1, t2);
}

/* Return true if T1 and T2 are related as allowed by STRICT.  STRICT
   is a bitwise-or of the COMPARE_* flags.  */

bool
comptypes (tree t1, tree t2, int strict)
{
  if (strict == COMPARE_STRICT)
    {
      if (t1 == t2)
        return true;

      if (t1 == error_mark_node || t2 == error_mark_node)
        return false;

      if (TYPE_STRUCTURAL_EQUALITY_P (t1) || TYPE_STRUCTURAL_EQUALITY_P (t2))
        /* At least one of the types requires structural equality, so
           perform a deep check. */
        return structural_comptypes (t1, t2, strict);

#ifdef ENABLE_CHECKING
      if (USE_CANONICAL_TYPES)
        {
          bool result = structural_comptypes (t1, t2, strict);
          
          if (result && TYPE_CANONICAL (t1) != TYPE_CANONICAL (t2))
            /* The two types are structurally equivalent, but their
               canonical types were different. This is a failure of the
               canonical type propagation code.*/
            internal_error 
              ("canonical types differ for identical types %T and %T", 
               t1, t2);
          else if (!result && TYPE_CANONICAL (t1) == TYPE_CANONICAL (t2))
            /* Two types are structurally different, but the canonical
               types are the same. This means we were over-eager in
               assigning canonical types. */
            internal_error 
              ("same canonical type node for different types %T and %T",
               t1, t2);
          
          return result;
        }
#else
      if (USE_CANONICAL_TYPES)
        return TYPE_CANONICAL (t1) == TYPE_CANONICAL (t2);
#endif
      else
        return structural_comptypes (t1, t2, strict);
    }
  else if (strict == COMPARE_STRUCTURAL)
    return structural_comptypes (t1, t2, COMPARE_STRICT);
  else
    return structural_comptypes (t1, t2, strict);
}

/* Returns 1 if TYPE1 is at least as qualified as TYPE2.  */

bool
at_least_as_qualified_p (const_tree type1, const_tree type2)
{
  int q1 = cp_type_quals (type1);
  int q2 = cp_type_quals (type2);

  /* All qualifiers for TYPE2 must also appear in TYPE1.  */
  return (q1 & q2) == q2;
}

/* Returns 1 if TYPE1 is more cv-qualified than TYPE2, -1 if TYPE2 is
   more cv-qualified that TYPE1, and 0 otherwise.  */

int
comp_cv_qualification (const_tree type1, const_tree type2)
{
  int q1 = cp_type_quals (type1);
  int q2 = cp_type_quals (type2);

  if (q1 == q2)
    return 0;

  if ((q1 & q2) == q2)
    return 1;
  else if ((q1 & q2) == q1)
    return -1;

  return 0;
}

/* Returns 1 if the cv-qualification signature of TYPE1 is a proper
   subset of the cv-qualification signature of TYPE2, and the types
   are similar.  Returns -1 if the other way 'round, and 0 otherwise.  */

int
comp_cv_qual_signature (tree type1, tree type2)
{
  if (comp_ptr_ttypes_real (type2, type1, -1))
    return 1;
  else if (comp_ptr_ttypes_real (type1, type2, -1))
    return -1;
  else
    return 0;
}
\f
/* Subroutines of `comptypes'.  */

/* Return true if two parameter type lists PARMS1 and PARMS2 are
   equivalent in the sense that functions with those parameter types
   can have equivalent types.  The two lists must be equivalent,
   element by element.  */

bool
compparms (const_tree parms1, const_tree parms2)
{
  const_tree t1, t2;

  /* An unspecified parmlist matches any specified parmlist
     whose argument types don't need default promotions.  */

  for (t1 = parms1, t2 = parms2;
       t1 || t2;
       t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
    {
      /* If one parmlist is shorter than the other,
         they fail to match.  */
      if (!t1 || !t2)
        return false;
      if (!same_type_p (TREE_VALUE (t1), TREE_VALUE (t2)))
        return false;
    }
  return true;
}

\f
/* Process a sizeof or alignof expression where the operand is a
   type.  */

tree
cxx_sizeof_or_alignof_type (tree type, enum tree_code op, bool complain)
{
  tree value;
  bool dependent_p;

  gcc_assert (op == SIZEOF_EXPR || op == ALIGNOF_EXPR);
  if (type == error_mark_node)
    return error_mark_node;

  type = non_reference (type);
  if (TREE_CODE (type) == METHOD_TYPE)
    {
      if (complain)
        pedwarn (input_location, pedantic ? OPT_pedantic : OPT_Wpointer_arith, 
                 "invalid application of %qs to a member function", 
                 operator_name_info[(int) op].name);
      value = size_one_node;
    }

  dependent_p = dependent_type_p (type);
  if (!dependent_p)
    complete_type (type);
  if (dependent_p
      /* VLA types will have a non-constant size.  In the body of an
         uninstantiated template, we don't need to try to compute the
         value, because the sizeof expression is not an integral
         constant expression in that case.  And, if we do try to
         compute the value, we'll likely end up with SAVE_EXPRs, which
         the template substitution machinery does not expect to see.  */
      || (processing_template_decl 
          && COMPLETE_TYPE_P (type)
          && TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST))
    {
      value = build_min (op, size_type_node, type);
      TREE_READONLY (value) = 1;
      return value;
    }

  return c_sizeof_or_alignof_type (input_location, complete_type (type),
                                   op == SIZEOF_EXPR,
                                   complain);
}

/* Return the size of the type, without producing any warnings for
   types whose size cannot be taken.  This routine should be used only
   in some other routine that has already produced a diagnostic about
   using the size of such a type.  */
tree 
cxx_sizeof_nowarn (tree type)
{
  if (TREE_CODE (type) == FUNCTION_TYPE
      || TREE_CODE (type) == VOID_TYPE
      || TREE_CODE (type) == ERROR_MARK)
    return size_one_node;
  else if (!COMPLETE_TYPE_P (type))
    return size_zero_node;
  else
    return cxx_sizeof_or_alignof_type (type, SIZEOF_EXPR, false);
}

/* Process a sizeof expression where the operand is an expression.  */

static tree
cxx_sizeof_expr (tree e, tsubst_flags_t complain)
{
  if (e == error_mark_node)
    return error_mark_node;

  if (processing_template_decl)
    {
      e = build_min (SIZEOF_EXPR, size_type_node, e);
      TREE_SIDE_EFFECTS (e) = 0;
      TREE_READONLY (e) = 1;

      return e;
    }

  /* To get the size of a static data member declared as an array of
     unknown bound, we need to instantiate it.  */
  if (TREE_CODE (e) == VAR_DECL
      && VAR_HAD_UNKNOWN_BOUND (e)
      && DECL_TEMPLATE_INSTANTIATION (e))
    instantiate_decl (e, /*defer_ok*/true, /*expl_inst_mem*/false);

  e = mark_type_use (e);

  if (TREE_CODE (e) == COMPONENT_REF
      && TREE_CODE (TREE_OPERAND (e, 1)) == FIELD_DECL
      && DECL_C_BIT_FIELD (TREE_OPERAND (e, 1)))
    {
      if (complain & tf_error)
        error ("invalid application of %<sizeof%> to a bit-field");
      else
        return error_mark_node;
      e = char_type_node;
    }
  else if (is_overloaded_fn (e))
    {
      if (complain & tf_error)
        permerror (input_location, "ISO C++ forbids applying %<sizeof%> to an expression of "
                   "function type");
      else
        return error_mark_node;
      e = char_type_node;
    }
  else if (type_unknown_p (e))
    {
      if (complain & tf_error)
        cxx_incomplete_type_error (e, TREE_TYPE (e));
      else
        return error_mark_node;
      e = char_type_node;
    }
  else
    e = TREE_TYPE (e);

  return cxx_sizeof_or_alignof_type (e, SIZEOF_EXPR, complain & tf_error);
}

/* Implement the __alignof keyword: Return the minimum required
   alignment of E, measured in bytes.  For VAR_DECL's and
   FIELD_DECL's return DECL_ALIGN (which can be set from an
   "aligned" __attribute__ specification).  */

static tree
cxx_alignof_expr (tree e, tsubst_flags_t complain)
{
  tree t;

  if (e == error_mark_node)
    return error_mark_node;

  if (processing_template_decl)
    {
      e = build_min (ALIGNOF_EXPR, size_type_node, e);
      TREE_SIDE_EFFECTS (e) = 0;
      TREE_READONLY (e) = 1;

      return e;
    }

  e = mark_type_use (e);

  if (TREE_CODE (e) == VAR_DECL)
    t = size_int (DECL_ALIGN_UNIT (e));
  else if (TREE_CODE (e) == COMPONENT_REF
           && TREE_CODE (TREE_OPERAND (e, 1)) == FIELD_DECL
           && DECL_C_BIT_FIELD (TREE_OPERAND (e, 1)))
    {
      if (complain & tf_error)
        error ("invalid application of %<__alignof%> to a bit-field");
      else
        return error_mark_node;
      t = size_one_node;
    }
  else if (TREE_CODE (e) == COMPONENT_REF
           && TREE_CODE (TREE_OPERAND (e, 1)) == FIELD_DECL)
    t = size_int (DECL_ALIGN_UNIT (TREE_OPERAND (e, 1)));
  else if (is_overloaded_fn (e))
    {
      if (complain & tf_error)
        permerror (input_location, "ISO C++ forbids applying %<__alignof%> to an expression of "
                   "function type");
      else
        return error_mark_node;
      if (TREE_CODE (e) == FUNCTION_DECL)
        t = size_int (DECL_ALIGN_UNIT (e));
      else
        t = size_one_node;
    }
  else if (type_unknown_p (e))
    {
      if (complain & tf_error)
        cxx_incomplete_type_error (e, TREE_TYPE (e));
      else
        return error_mark_node;
      t = size_one_node;
    }
  else
    return cxx_sizeof_or_alignof_type (TREE_TYPE (e), ALIGNOF_EXPR, 
                                       complain & tf_error);

  return fold_convert (size_type_node, t);
}

/* Process a sizeof or alignof expression E with code OP where the operand
   is an expression.  */

tree
cxx_sizeof_or_alignof_expr (tree e, enum tree_code op, bool complain)
{
  if (op == SIZEOF_EXPR)
    return cxx_sizeof_expr (e, complain? tf_warning_or_error : tf_none);
  else
    return cxx_alignof_expr (e, complain? tf_warning_or_error : tf_none);
}
\f
/* EXPR is being used in a context that is not a function call.
   Enforce:

     [expr.ref]

     The expression can be used only as the left-hand operand of a
     member function call.

     [expr.mptr.operator]

     If the result of .* or ->* is a function, then that result can be
     used only as the operand for the function call operator ().

   by issuing an error message if appropriate.  Returns true iff EXPR
   violates these rules.  */

bool
invalid_nonstatic_memfn_p (const_tree expr, tsubst_flags_t complain)
{
  if (expr && DECL_NONSTATIC_MEMBER_FUNCTION_P (expr))
    {
      if (complain & tf_error)
        error ("invalid use of non-static member function");
      return true;
    }
  return false;
}

/* If EXP is a reference to a bitfield, and the type of EXP does not
   match the declared type of the bitfield, return the declared type
   of the bitfield.  Otherwise, return NULL_TREE.  */

tree
is_bitfield_expr_with_lowered_type (const_tree exp)
{
  switch (TREE_CODE (exp))
    {
    case COND_EXPR:
      if (!is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 1)
                                               ? TREE_OPERAND (exp, 1)
                                               : TREE_OPERAND (exp, 0)))
        return NULL_TREE;
      return is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 2));

    case COMPOUND_EXPR:
      return is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 1));

    case MODIFY_EXPR:
    case SAVE_EXPR:
      return is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 0));

    case COMPONENT_REF:
      {
        tree field;
        
        field = TREE_OPERAND (exp, 1);
        if (TREE_CODE (field) != FIELD_DECL || !DECL_BIT_FIELD_TYPE (field))
          return NULL_TREE;
        if (same_type_ignoring_top_level_qualifiers_p
            (TREE_TYPE (exp), DECL_BIT_FIELD_TYPE (field)))
          return NULL_TREE;
        return DECL_BIT_FIELD_TYPE (field);
      }

    CASE_CONVERT:
      if (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (exp, 0)))
          == TYPE_MAIN_VARIANT (TREE_TYPE (exp)))
        return is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 0));
      /* Fallthrough.  */

    default:
      return NULL_TREE;
    }
}

/* Like is_bitfield_with_lowered_type, except that if EXP is not a
   bitfield with a lowered type, the type of EXP is returned, rather
   than NULL_TREE.  */

tree
unlowered_expr_type (const_tree exp)
{
  tree type;

  type = is_bitfield_expr_with_lowered_type (exp);
  if (!type)
    type = TREE_TYPE (exp);

  return type;
}

/* Perform the conversions in [expr] that apply when an lvalue appears
   in an rvalue context: the lvalue-to-rvalue, array-to-pointer, and
   function-to-pointer conversions.  In addition, manifest constants
   are replaced by their values, and bitfield references are converted
   to their declared types. Note that this function does not perform the
   lvalue-to-rvalue conversion for class types. If you need that conversion
   to for class types, then you probably need to use force_rvalue.

   Although the returned value is being used as an rvalue, this
   function does not wrap the returned expression in a
   NON_LVALUE_EXPR; the caller is expected to be mindful of the fact
   that the return value is no longer an lvalue.  */

tree
decay_conversion (tree exp)
{
  tree type;
  enum tree_code code;

  type = TREE_TYPE (exp);
  if (type == error_mark_node)
    return error_mark_node;

  exp = mark_rvalue_use (exp);

  exp = resolve_nondeduced_context (exp);
  if (type_unknown_p (exp))
    {
      cxx_incomplete_type_error (exp, TREE_TYPE (exp));
      return error_mark_node;
    }

  exp = decl_constant_value (exp);
  if (error_operand_p (exp))
    return error_mark_node;

  /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
     Leave such NOP_EXPRs, since RHS is being used in non-lvalue context.  */
  code = TREE_CODE (type);
  if (code == VOID_TYPE)
    {
      error ("void value not ignored as it ought to be");
      return error_mark_node;
    }
  if (invalid_nonstatic_memfn_p (exp, tf_warning_or_error))
    return error_mark_node;
  if (code == FUNCTION_TYPE || is_overloaded_fn (exp))
    return cp_build_unary_op (ADDR_EXPR, exp, 0, tf_warning_or_error);
  if (code == ARRAY_TYPE)
    {
      tree adr;
      tree ptrtype;

      if (TREE_CODE (exp) == INDIRECT_REF)
        return build_nop (build_pointer_type (TREE_TYPE (type)),
                          TREE_OPERAND (exp, 0));

      if (TREE_CODE (exp) == COMPOUND_EXPR)
        {
          tree op1 = decay_conversion (TREE_OPERAND (exp, 1));
          return build2 (COMPOUND_EXPR, TREE_TYPE (op1),
                         TREE_OPERAND (exp, 0), op1);
        }

      if (!lvalue_p (exp)
          && ! (TREE_CODE (exp) == CONSTRUCTOR && TREE_STATIC (exp)))
        {
          error ("invalid use of non-lvalue array");
          return error_mark_node;
        }

      ptrtype = build_pointer_type (TREE_TYPE (type));

      if (TREE_CODE (exp) == VAR_DECL)
        {
          if (!cxx_mark_addressable (exp))
            return error_mark_node;
          adr = build_nop (ptrtype, build_address (exp));
          return adr;
        }
      /* This way is better for a COMPONENT_REF since it can
         simplify the offset for a component.  */
      adr = cp_build_unary_op (ADDR_EXPR, exp, 1, tf_warning_or_error);
      return cp_convert (ptrtype, adr);
    }

  /* If a bitfield is used in a context where integral promotion
     applies, then the caller is expected to have used
     default_conversion.  That function promotes bitfields correctly
     before calling this function.  At this point, if we have a
     bitfield referenced, we may assume that is not subject to
     promotion, and that, therefore, the type of the resulting rvalue
     is the declared type of the bitfield.  */
  exp = convert_bitfield_to_declared_type (exp);

  /* We do not call rvalue() here because we do not want to wrap EXP
     in a NON_LVALUE_EXPR.  */

  /* [basic.lval]

     Non-class rvalues always have cv-unqualified types.  */
  type = TREE_TYPE (exp);
  if (!CLASS_TYPE_P (type) && cv_qualified_p (type))
    exp = build_nop (cv_unqualified (type), exp);

  return exp;
}

/* Perform preparatory conversions, as part of the "usual arithmetic
   conversions".  In particular, as per [expr]:

     Whenever an lvalue expression appears as an operand of an
     operator that expects the rvalue for that operand, the
     lvalue-to-rvalue, array-to-pointer, or function-to-pointer
     standard conversions are applied to convert the expression to an
     rvalue.

   In addition, we perform integral promotions here, as those are
   applied to both operands to a binary operator before determining
   what additional conversions should apply.  */

tree
default_conversion (tree exp)
{
  /* Check for target-specific promotions.  */
  tree promoted_type = targetm.promoted_type (TREE_TYPE (exp));
  if (promoted_type)
    exp = cp_convert (promoted_type, exp);
  /* Perform the integral promotions first so that bitfield
     expressions (which may promote to "int", even if the bitfield is
     declared "unsigned") are promoted correctly.  */
  else if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (TREE_TYPE (exp)))
    exp = perform_integral_promotions (exp);
  /* Perform the other conversions.  */
  exp = decay_conversion (exp);

  return exp;
}

/* EXPR is an expression with an integral or enumeration type.
   Perform the integral promotions in [conv.prom], and return the
   converted value.  */

tree
perform_integral_promotions (tree expr)
{
  tree type;
  tree promoted_type;

  expr = mark_rvalue_use (expr);

  /* [conv.prom]

     If the bitfield has an enumerated type, it is treated as any
     other value of that type for promotion purposes.  */
  type = is_bitfield_expr_with_lowered_type (expr);
  if (!type || TREE_CODE (type) != ENUMERAL_TYPE)
    type = TREE_TYPE (expr);
  gcc_assert (INTEGRAL_OR_ENUMERATION_TYPE_P (type));
  promoted_type = type_promotes_to (type);
  if (type != promoted_type)
    expr = cp_convert (promoted_type, expr);
  return expr;
}

/* Returns nonzero iff exp is a STRING_CST or the result of applying
   decay_conversion to one.  */

int
string_conv_p (const_tree totype, const_tree exp, int warn)
{
  tree t;

  if (TREE_CODE (totype) != POINTER_TYPE)
    return 0;

  t = TREE_TYPE (totype);
  if (!same_type_p (t, char_type_node)
      && !same_type_p (t, char16_type_node)
      && !same_type_p (t, char32_type_node)
      && !same_type_p (t, wchar_type_node))
    return 0;

  if (TREE_CODE (exp) == STRING_CST)
    {
      /* Make sure that we don't try to convert between char and wide chars.  */
      if (!same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (exp))), t))
        return 0;
    }
  else
    {
      /* Is this a string constant which has decayed to 'const char *'?  */
      t = build_pointer_type (build_qualified_type (t, TYPE_QUAL_CONST));
      if (!same_type_p (TREE_TYPE (exp), t))
        return 0;
      STRIP_NOPS (exp);
      if (TREE_CODE (exp) != ADDR_EXPR
          || TREE_CODE (TREE_OPERAND (exp, 0)) != STRING_CST)
        return 0;
    }

  /* This warning is not very useful, as it complains about printf.  */
  if (warn)
    warning (OPT_Wwrite_strings,
             "deprecated conversion from string constant to %qT",
             totype);

  return 1;
}

/* Given a COND_EXPR, MIN_EXPR, or MAX_EXPR in T, return it in a form that we
   can, for example, use as an lvalue.  This code used to be in
   unary_complex_lvalue, but we needed it to deal with `a = (d == c) ? b : c'
   expressions, where we're dealing with aggregates.  But now it's again only
   called from unary_complex_lvalue.  The case (in particular) that led to
   this was with CODE == ADDR_EXPR, since it's not an lvalue when we'd
   get it there.  */

static tree
rationalize_conditional_expr (enum tree_code code, tree t,
                              tsubst_flags_t complain)
{
  /* For MIN_EXPR or MAX_EXPR, fold-const.c has arranged things so that
     the first operand is always the one to be used if both operands
     are equal, so we know what conditional expression this used to be.  */
  if (TREE_CODE (t) == MIN_EXPR || TREE_CODE (t) == MAX_EXPR)
    {
      tree op0 = TREE_OPERAND (t, 0);
      tree op1 = TREE_OPERAND (t, 1);

      /* The following code is incorrect if either operand side-effects.  */
      gcc_assert (!TREE_SIDE_EFFECTS (op0)
                  && !TREE_SIDE_EFFECTS (op1));
      return
        build_conditional_expr (build_x_binary_op ((TREE_CODE (t) == MIN_EXPR
                                                    ? LE_EXPR : GE_EXPR),
                                                   op0, TREE_CODE (op0),
                                                   op1, TREE_CODE (op1),
                                                   /*overloaded_p=*/NULL,
                                                   complain),
                                cp_build_unary_op (code, op0, 0, complain),
                                cp_build_unary_op (code, op1, 0, complain),
                                complain);
    }

  return
    build_conditional_expr (TREE_OPERAND (t, 0),
                            cp_build_unary_op (code, TREE_OPERAND (t, 1), 0,
                                               complain),
                            cp_build_unary_op (code, TREE_OPERAND (t, 2), 0,
                                               complain),
                            complain);
}

/* Given the TYPE of an anonymous union field inside T, return the
   FIELD_DECL for the field.  If not found return NULL_TREE.  Because
   anonymous unions can nest, we must also search all anonymous unions
   that are directly reachable.  */

tree
lookup_anon_field (tree t, tree type)
{
  tree field;

  for (field = TYPE_FIELDS (t); field; field = TREE_CHAIN (field))
    {
      if (TREE_STATIC (field))
        continue;
      if (TREE_CODE (field) != FIELD_DECL || DECL_ARTIFICIAL (field))
        continue;

      /* If we find it directly, return the field.  */
      if (DECL_NAME (field) == NULL_TREE
          && type == TYPE_MAIN_VARIANT (TREE_TYPE (field)))
        {
          return field;
        }

      /* Otherwise, it could be nested, search harder.  */
      if (DECL_NAME (field) == NULL_TREE
          && ANON_AGGR_TYPE_P (TREE_TYPE (field)))
        {
          tree subfield = lookup_anon_field (TREE_TYPE (field), type);
          if (subfield)
            return subfield;
        }
    }
  return NULL_TREE;
}

/* Build an expression representing OBJECT.MEMBER.  OBJECT is an
   expression; MEMBER is a DECL or baselink.  If ACCESS_PATH is
   non-NULL, it indicates the path to the base used to name MEMBER.
   If PRESERVE_REFERENCE is true, the expression returned will have
   REFERENCE_TYPE if the MEMBER does.  Otherwise, the expression
   returned will have the type referred to by the reference.

   This function does not perform access control; that is either done
   earlier by the parser when the name of MEMBER is resolved to MEMBER
   itself, or later when overload resolution selects one of the
   functions indicated by MEMBER.  */

tree
build_class_member_access_expr (tree object, tree member,
                                tree access_path, bool preserve_reference,
                                tsubst_flags_t complain)
{
  tree object_type;
  tree member_scope;
  tree result = NULL_TREE;

  if (error_operand_p (object) || error_operand_p (member))
    return error_mark_node;

  gcc_assert (DECL_P (member) || BASELINK_P (member));

  /* [expr.ref]

     The type of the first expression shall be "class object" (of a
     complete type).  */
  object_type = TREE_TYPE (object);
  if (!currently_open_class (object_type)
      && !complete_type_or_else (object_type, object))
    return error_mark_node;
  if (!CLASS_TYPE_P (object_type))
    {
      if (complain & tf_error)
        error ("request for member %qD in %qE, which is of non-class type %qT",
               member, object, object_type);
      return error_mark_node;
    }

  /* The standard does not seem to actually say that MEMBER must be a
     member of OBJECT_TYPE.  However, that is clearly what is
     intended.  */
  if (DECL_P (member))
    {
      member_scope = DECL_CLASS_CONTEXT (member);
      mark_used (member);
      if (TREE_DEPRECATED (member))
        warn_deprecated_use (member, NULL_TREE);
    }
  else
    member_scope = BINFO_TYPE (BASELINK_ACCESS_BINFO (member));
  /* If MEMBER is from an anonymous aggregate, MEMBER_SCOPE will
     presently be the anonymous union.  Go outwards until we find a
     type related to OBJECT_TYPE.  */
  while (ANON_AGGR_TYPE_P (member_scope)
         && !same_type_ignoring_top_level_qualifiers_p (member_scope,
                                                        object_type))
    member_scope = TYPE_CONTEXT (member_scope);
  if (!member_scope || !DERIVED_FROM_P (member_scope, object_type))
    {
      if (complain & tf_error)
        {
          if (TREE_CODE (member) == FIELD_DECL)
            error ("invalid use of nonstatic data member %qE", member);
          else
            error ("%qD is not a member of %qT", member, object_type);
        }
      return error_mark_node;
    }

  /* Transform `(a, b).x' into `(*(a, &b)).x', `(a ? b : c).x' into
     `(*(a ?  &b : &c)).x', and so on.  A COND_EXPR is only an lvalue
     in the front end; only _DECLs and _REFs are lvalues in the back end.  */
  {
    tree temp = unary_complex_lvalue (ADDR_EXPR, object);
    if (temp)
      object = cp_build_indirect_ref (temp, RO_NULL, complain);
  }

  /* In [expr.ref], there is an explicit list of the valid choices for
     MEMBER.  We check for each of those cases here.  */
  if (TREE_CODE (member) == VAR_DECL)
    {
      /* A static data member.  */
      result = member;
      /* If OBJECT has side-effects, they are supposed to occur.  */
      if (TREE_SIDE_EFFECTS (object))
        result = build2 (COMPOUND_EXPR, TREE_TYPE (result), object, result);
    }
  else if (TREE_CODE (member) == FIELD_DECL)
    {
      /* A non-static data member.  */
      bool null_object_p;
      int type_quals;
      tree member_type;

      null_object_p = (TREE_CODE (object) == INDIRECT_REF
                       && integer_zerop (TREE_OPERAND (object, 0)));

      /* Convert OBJECT to the type of MEMBER.  */
      if (!same_type_p (TYPE_MAIN_VARIANT (object_type),
                        TYPE_MAIN_VARIANT (member_scope)))
        {
          tree binfo;
          base_kind kind;

          binfo = lookup_base (access_path ? access_path : object_type,
                               member_scope, ba_unique,  &kind);
          if (binfo == error_mark_node)
            return error_mark_node;

          /* It is invalid to try to get to a virtual base of a
             NULL object.  The most common cause is invalid use of
             offsetof macro.  */
          if (null_object_p && kind == bk_via_virtual)
            {
              if (complain & tf_error)
                {
                  error ("invalid access to non-static data member %qD of "
                         "NULL object",
                         member);
                  error ("(perhaps the %<offsetof%> macro was used incorrectly)");
                }
              return error_mark_node;
            }

          /* Convert to the base.  */
          object = build_base_path (PLUS_EXPR, object, binfo,
                                    /*nonnull=*/1);
          /* If we found the base successfully then we should be able
             to convert to it successfully.  */
          gcc_assert (object != error_mark_node);
        }

      /* Complain about other invalid uses of offsetof, even though they will
         give the right answer.  Note that we complain whether or not they
         actually used the offsetof macro, since there's no way to know at this
         point.  So we just give a warning, instead of a pedwarn.  */
      /* Do not produce this warning for base class field references, because
         we know for a fact that didn't come from offsetof.  This does occur
         in various testsuite cases where a null object is passed where a
         vtable access is required.  */
      if (null_object_p && warn_invalid_offsetof
          && CLASSTYPE_NON_STD_LAYOUT (object_type)
          && !DECL_FIELD_IS_BASE (member)
          && cp_unevaluated_operand == 0
          && (complain & tf_warning))
        {
          warning (OPT_Winvalid_offsetof, 
                   "invalid access to non-static data member %qD "
                   " of NULL object", member);
          warning (OPT_Winvalid_offsetof, 
                   "(perhaps the %<offsetof%> macro was used incorrectly)");
        }

      /* If MEMBER is from an anonymous aggregate, we have converted
         OBJECT so that it refers to the class containing the
         anonymous union.  Generate a reference to the anonymous union
         itself, and recur to find MEMBER.  */
      if (ANON_AGGR_TYPE_P (DECL_CONTEXT (member))
          /* When this code is called from build_field_call, the
             object already has the type of the anonymous union.
             That is because the COMPONENT_REF was already
             constructed, and was then disassembled before calling
             build_field_call.  After the function-call code is
             cleaned up, this waste can be eliminated.  */
          && (!same_type_ignoring_top_level_qualifiers_p
              (TREE_TYPE (object), DECL_CONTEXT (member))))
        {
          tree anonymous_union;

          anonymous_union = lookup_anon_field (TREE_TYPE (object),
                                               DECL_CONTEXT (member));
          object = build_class_member_access_expr (object,
                                                   anonymous_union,
                                                   /*access_path=*/NULL_TREE,
                                                   preserve_reference,
                                                   complain);
        }

      /* Compute the type of the field, as described in [expr.ref].  */
      type_quals = TYPE_UNQUALIFIED;
      member_type = TREE_TYPE (member);
      if (TREE_CODE (member_type) != REFERENCE_TYPE)
        {
          type_quals = (cp_type_quals (member_type)
                        | cp_type_quals (object_type));

          /* A field is const (volatile) if the enclosing object, or the
             field itself, is const (volatile).  But, a mutable field is
             not const, even within a const object.  */
          if (DECL_MUTABLE_P (member))
            type_quals &= ~TYPE_QUAL_CONST;
          member_type = cp_build_qualified_type (member_type, type_quals);
        }

      result = build3 (COMPONENT_REF, member_type, object, member,
                       NULL_TREE);
      result = fold_if_not_in_template (result);

      /* Mark the expression const or volatile, as appropriate.  Even
         though we've dealt with the type above, we still have to mark the
         expression itself.  */
      if (type_quals & TYPE_QUAL_CONST)
        TREE_READONLY (result) = 1;
      if (type_quals & TYPE_QUAL_VOLATILE)
        TREE_THIS_VOLATILE (result) = 1;
    }
  else if (BASELINK_P (member))
    {
      /* The member is a (possibly overloaded) member function.  */
      tree functions;
      tree type;

      /* If the MEMBER is exactly one static member function, then we
         know the type of the expression.  Otherwise, we must wait
         until overload resolution has been performed.  */
      functions = BASELINK_FUNCTIONS (member);
      if (TREE_CODE (functions) == FUNCTION_DECL
          && DECL_STATIC_FUNCTION_P (functions))
        type = TREE_TYPE (functions);
      else
        type = unknown_type_node;
      /* Note that we do not convert OBJECT to the BASELINK_BINFO
         base.  That will happen when the function is called.  */
      result = build3 (COMPONENT_REF, type, object, member, NULL_TREE);
    }
  else if (TREE_CODE (member) == CONST_DECL)
    {
      /* The member is an enumerator.  */
      result = member;
      /* If OBJECT has side-effects, they are supposed to occur.  */
      if (TREE_SIDE_EFFECTS (object))
        result = build2 (COMPOUND_EXPR, TREE_TYPE (result),
                         object, result);
    }
  else
    {
      if (complain & tf_error)
        error ("invalid use of %qD", member);
      return error_mark_node;
    }

  if (!preserve_reference)
    /* [expr.ref]

       If E2 is declared to have type "reference to T", then ... the
       type of E1.E2 is T.  */
    result = convert_from_reference (result);

  return result;
}

/* Return the destructor denoted by OBJECT.SCOPE::DTOR_NAME, or, if
   SCOPE is NULL, by OBJECT.DTOR_NAME, where DTOR_NAME is ~type.  */

static tree
lookup_destructor (tree object, tree scope, tree dtor_name)
{
  tree object_type = TREE_TYPE (object);
  tree dtor_type = TREE_OPERAND (dtor_name, 0);
  tree expr;

  if (scope && !check_dtor_name (scope, dtor_type))
    {
      error ("qualified type %qT does not match destructor name ~%qT",
             scope, dtor_type);
      return error_mark_node;
    }
  if (TREE_CODE (dtor_type) == IDENTIFIER_NODE)
    {
      /* In a template, names we can't find a match for are still accepted
         destructor names, and we check them here.  */
      if (check_dtor_name (object_type, dtor_type))
        dtor_type = object_type;
      else
        {
          error ("object type %qT does not match destructor name ~%qT",
                 object_type, dtor_type);
          return error_mark_node;
        }
      
    }
  else if (!DERIVED_FROM_P (dtor_type, TYPE_MAIN_VARIANT (object_type)))
    {
      error ("the type being destroyed is %qT, but the destructor refers to %qT",
             TYPE_MAIN_VARIANT (object_type), dtor_type);
      return error_mark_node;
    }
  expr = lookup_member (dtor_type, complete_dtor_identifier,
                        /*protect=*/1, /*want_type=*/false);
  expr = (adjust_result_of_qualified_name_lookup
          (expr, dtor_type, object_type));
  return expr;
}

/* An expression of the form "A::template B" has been resolved to
   DECL.  Issue a diagnostic if B is not a template or template
   specialization.  */

void
check_template_keyword (tree decl)
{
  /* The standard says:

      [temp.names]

      If a name prefixed by the keyword template is not a member
      template, the program is ill-formed.

     DR 228 removed the restriction that the template be a member
     template.

     DR 96, if accepted would add the further restriction that explicit
     template arguments must be provided if the template keyword is
     used, but, as of 2005-10-16, that DR is still in "drafting".  If
     this DR is accepted, then the semantic checks here can be
     simplified, as the entity named must in fact be a template
     specialization, rather than, as at present, a set of overloaded
     functions containing at least one template function.  */
  if (TREE_CODE (decl) != TEMPLATE_DECL
      && TREE_CODE (decl) != TEMPLATE_ID_EXPR)
    {
      if (!is_overloaded_fn (decl))
        permerror (input_location, "%qD is not a template", decl);
      else
        {
          tree fns;
          fns = decl;
          if (BASELINK_P (fns))
            fns = BASELINK_FUNCTIONS (fns);
          while (fns)
            {
              tree fn = OVL_CURRENT (fns);
              if (TREE_CODE (fn) == TEMPLATE_DECL
                  || TREE_CODE (fn) == TEMPLATE_ID_EXPR)
                break;
              if (TREE_CODE (fn) == FUNCTION_DECL
                  && DECL_USE_TEMPLATE (fn)
                  && PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (fn)))
                break;
              fns = OVL_NEXT (fns);
            }
          if (!fns)
            permerror (input_location, "%qD is not a template", decl);
        }
    }
}

/* This function is called by the parser to process a class member
   access expression of the form OBJECT.NAME.  NAME is a node used by
   the parser to represent a name; it is not yet a DECL.  It may,
   however, be a BASELINK where the BASELINK_FUNCTIONS is a
   TEMPLATE_ID_EXPR.  Templates must be looked up by the parser, and
   there is no reason to do the lookup twice, so the parser keeps the
   BASELINK.  TEMPLATE_P is true iff NAME was explicitly declared to
   be a template via the use of the "A::template B" syntax.  */

tree
finish_class_member_access_expr (tree object, tree name, bool template_p,
                                 tsubst_flags_t complain)
{
  tree expr;
  tree object_type;
  tree member;
  tree access_path = NULL_TREE;
  tree orig_object = object;
  tree orig_name = name;

  if (object == error_mark_node || name == error_mark_node)
    return error_mark_node;

  /* If OBJECT is an ObjC class instance, we must obey ObjC access rules.  */
  if (!objc_is_public (object, name))
    return error_mark_node;

  object_type = TREE_TYPE (object);

  if (processing_template_decl)
    {
      if (/* If OBJECT_TYPE is dependent, so is OBJECT.NAME.  */
          dependent_type_p (object_type)
          /* If NAME is just an IDENTIFIER_NODE, then the expression
             is dependent.  */
          || TREE_CODE (object) == IDENTIFIER_NODE
          /* If NAME is "f<args>", where either 'f' or 'args' is
             dependent, then the expression is dependent.  */
          || (TREE_CODE (name) == TEMPLATE_ID_EXPR
              && dependent_template_id_p (TREE_OPERAND (name, 0),
                                          TREE_OPERAND (name, 1)))
          /* If NAME is "T::X" where "T" is dependent, then the
             expression is dependent.  */
          || (TREE_CODE (name) == SCOPE_REF
              && TYPE_P (TREE_OPERAND (name, 0))
              && dependent_type_p (TREE_OPERAND (name, 0))))
        return build_min_nt (COMPONENT_REF, object, name, NULL_TREE);
      object = build_non_dependent_expr (object);
    }

  /* [expr.ref]

     The type of the first expression shall be "class object" (of a
     complete type).  */
  if (!currently_open_class (object_type)
      && !complete_type_or_else (object_type, object))
    return error_mark_node;
  if (!CLASS_TYPE_P (object_type))
    {
      if (complain & tf_error)
        error ("request for member %qD in %qE, which is of non-class type %qT",
               name, object, object_type);
      return error_mark_node;
    }

  if (BASELINK_P (name))
    /* A member function that has already been looked up.  */
    member = name;
  else
    {
      bool is_template_id = false;
      tree template_args = NULL_TREE;
      tree scope;

      if (TREE_CODE (name) == TEMPLATE_ID_EXPR)
        {
          is_template_id = true;
          template_args = TREE_OPERAND (name, 1);
          name = TREE_OPERAND (name, 0);

          if (TREE_CODE (name) == OVERLOAD)
            name = DECL_NAME (get_first_fn (name));
          else if (DECL_P (name))
            name = DECL_NAME (name);
        }

      if (TREE_CODE (name) == SCOPE_REF)
        {
          /* A qualified name.  The qualifying class or namespace `S'
             has already been looked up; it is either a TYPE or a
             NAMESPACE_DECL.  */
          scope = TREE_OPERAND (name, 0);
          name = TREE_OPERAND (name, 1);

          /* If SCOPE is a namespace, then the qualified name does not
             name a member of OBJECT_TYPE.  */
          if (TREE_CODE (scope) == NAMESPACE_DECL)
            {
              if (complain & tf_error)
                error ("%<%D::%D%> is not a member of %qT",
                       scope, name, object_type);
              return error_mark_node;
            }

          gcc_assert (CLASS_TYPE_P (scope));
          gcc_assert (TREE_CODE (name) == IDENTIFIER_NODE
                      || TREE_CODE (name) == BIT_NOT_EXPR);

          if (constructor_name_p (name, scope))
            {
              if (complain & tf_error)
                error ("cannot call constructor %<%T::%D%> directly",
                       scope, name);
              return error_mark_node;
            }

          /* Find the base of OBJECT_TYPE corresponding to SCOPE.  */
          access_path = lookup_base (object_type, scope, ba_check, NULL);
          if (access_path == error_mark_node)
            return error_mark_node;
          if (!access_path)
            {
              if (complain & tf_error)
                error ("%qT is not a base of %qT", scope, object_type);
              return error_mark_node;
            }
        }
      else
        {
          scope = NULL_TREE;
          access_path = object_type;
        }

      if (TREE_CODE (name) == BIT_NOT_EXPR)
        member = lookup_destructor (object, scope, name);
      else
        {
          /* Look up the member.  */
          member = lookup_member (access_path, name, /*protect=*/1,
                                  /*want_type=*/false);
          if (member == NULL_TREE)
            {
              if (complain & tf_error)
                error ("%qD has no member named %qE", object_type, name);
              return error_mark_node;
            }
          if (member == error_mark_node)
            return error_mark_node;
        }

      if (is_template_id)
        {
          tree templ = member;

          if (BASELINK_P (templ))
            templ = lookup_template_function (templ, template_args);
          else
            {
              if (complain & tf_error)
                error ("%qD is not a member template function", name);
              return error_mark_node;
            }
        }
    }

  if (TREE_DEPRECATED (member))
    warn_deprecated_use (member, NULL_TREE);

  if (template_p)
    check_template_keyword (member);

  expr = build_class_member_access_expr (object, member, access_path,
                                         /*preserve_reference=*/false,
                                         complain);
  if (processing_template_decl && expr != error_mark_node)
    {
      if (BASELINK_P (member))
        {
          if (TREE_CODE (orig_name) == SCOPE_REF)
            BASELINK_QUALIFIED_P (member) = 1;
          orig_name = member;
        }
      return build_min_non_dep (COMPONENT_REF, expr,
                                orig_object, orig_name,
                                NULL_TREE);
    }

  return expr;
}

/* Return an expression for the MEMBER_NAME field in the internal
   representation of PTRMEM, a pointer-to-member function.  (Each
   pointer-to-member function type gets its own RECORD_TYPE so it is
   more convenient to access the fields by name than by FIELD_DECL.)
   This routine converts the NAME to a FIELD_DECL and then creates the
   node for the complete expression.  */

tree
build_ptrmemfunc_access_expr (tree ptrmem, tree member_name)
{
  tree ptrmem_type;
  tree member;
  tree member_type;

  /* This code is a stripped down version of
     build_class_member_access_expr.  It does not work to use that
     routine directly because it expects the object to be of class
     type.  */
  ptrmem_type = TREE_TYPE (ptrmem);
  gcc_assert (TYPE_PTRMEMFUNC_P (ptrmem_type));
  member = lookup_member (ptrmem_type, member_name, /*protect=*/0,
                          /*want_type=*/false);
  member_type = cp_build_qualified_type (TREE_TYPE (member),
                                         cp_type_quals (ptrmem_type));
  return fold_build3_loc (input_location,
                      COMPONENT_REF, member_type,
                      ptrmem, member, NULL_TREE);
}

/* Given an expression PTR for a pointer, return an expression
   for the value pointed to.
   ERRORSTRING is the name of the operator to appear in error messages.

   This function may need to overload OPERATOR_FNNAME.
   Must also handle REFERENCE_TYPEs for C++.  */

tree
build_x_indirect_ref (tree expr, ref_operator errorstring, 
                      tsubst_flags_t complain)
{
  tree orig_expr = expr;
  tree rval;

  if (processing_template_decl)
    {
      /* Retain the type if we know the operand is a pointer so that
         describable_type doesn't make auto deduction break.  */
      if (TREE_TYPE (expr) && POINTER_TYPE_P (TREE_TYPE (expr)))
        return build_min (INDIRECT_REF, TREE_TYPE (TREE_TYPE (expr)), expr);
      if (type_dependent_expression_p (expr))
        return build_min_nt (INDIRECT_REF, expr);
      expr = build_non_dependent_expr (expr);
    }

  rval = build_new_op (INDIRECT_REF, LOOKUP_NORMAL, expr, NULL_TREE,
                       NULL_TREE, /*overloaded_p=*/NULL, complain);
  if (!rval)
    rval = cp_build_indirect_ref (expr, errorstring, complain);

  if (processing_template_decl && rval != error_mark_node)
    return build_min_non_dep (INDIRECT_REF, rval, orig_expr);
  else
    return rval;
}

/* Helper function called from c-common.  */
tree
build_indirect_ref (location_t loc __attribute__ ((__unused__)),
                    tree ptr, ref_operator errorstring)
{
  return cp_build_indirect_ref (ptr, errorstring, tf_warning_or_error);
}

tree
cp_build_indirect_ref (tree ptr, ref_operator errorstring, 
                       tsubst_flags_t complain)
{
  tree pointer, type;

  if (ptr == error_mark_node)
    return error_mark_node;

  if (ptr == current_class_ptr)
    return current_class_ref;

  pointer = (TREE_CODE (TREE_TYPE (ptr)) == REFERENCE_TYPE
             ? ptr : decay_conversion (ptr));
  type = TREE_TYPE (pointer);

  if (POINTER_TYPE_P (type))
    {
      /* [expr.unary.op]

         If the type of the expression is "pointer to T," the type
         of  the  result  is  "T."  */
      tree t = TREE_TYPE (type);

      if (CONVERT_EXPR_P (ptr)
          || TREE_CODE (ptr) == VIEW_CONVERT_EXPR)
        {
          /* If a warning is issued, mark it to avoid duplicates from
             the backend.  This only needs to be done at
             warn_strict_aliasing > 2.  */
          if (warn_strict_aliasing > 2)
            if (strict_aliasing_warning (TREE_TYPE (TREE_OPERAND (ptr, 0)),
                                         type, TREE_OPERAND (ptr, 0)))
              TREE_NO_WARNING (ptr) = 1;
        }

      if (VOID_TYPE_P (t))
        {
          /* A pointer to incomplete type (other than cv void) can be
             dereferenced [expr.unary.op]/1  */
          if (complain & tf_error)
            error ("%qT is not a pointer-to-object type", type);
          return error_mark_node;
        }
      else if (TREE_CODE (pointer) == ADDR_EXPR
               && same_type_p (t, TREE_TYPE (TREE_OPERAND (pointer, 0))))
        /* The POINTER was something like `&x'.  We simplify `*&x' to
           `x'.  */
        return TREE_OPERAND (pointer, 0);
      else
        {
          tree ref = build1 (INDIRECT_REF, t, pointer);

          /* We *must* set TREE_READONLY when dereferencing a pointer to const,
             so that we get the proper error message if the result is used
             to assign to.  Also, &* is supposed to be a no-op.  */
          TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
          TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
          TREE_SIDE_EFFECTS (ref)
            = (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (pointer));
          return ref;
        }
    }
  else if (!(complain & tf_error))
    /* Don't emit any errors; we'll just return ERROR_MARK_NODE later.  */
    ;
  /* `pointer' won't be an error_mark_node if we were given a
     pointer to member, so it's cool to check for this here.  */
  else if (TYPE_PTR_TO_MEMBER_P (type))
    switch (errorstring)
      {
         case RO_ARRAY_INDEXING:
           error ("invalid use of array indexing on pointer to member");
           break;
         case RO_UNARY_STAR:
           error ("invalid use of unary %<*%> on pointer to member");
           break;
         case RO_IMPLICIT_CONVERSION:
           error ("invalid use of implicit conversion on pointer to member");
           break;
         default:
           gcc_unreachable ();
      }
  else if (pointer != error_mark_node)
    switch (errorstring)
      {
         case RO_NULL:
           error ("invalid type argument");
           break;
         case RO_ARRAY_INDEXING:
           error ("invalid type argument of array indexing");
           break;
         case RO_UNARY_STAR:
           error ("invalid type argument of unary %<*%>");
           break;
         case RO_IMPLICIT_CONVERSION:
           error ("invalid type argument of implicit conversion");
           break;
         default:
           gcc_unreachable ();
      }
  return error_mark_node;
}

/* This handles expressions of the form "a[i]", which denotes
   an array reference.

   This is logically equivalent in C to *(a+i), but we may do it differently.
   If A is a variable or a member, we generate a primitive ARRAY_REF.
   This avoids forcing the array out of registers, and can work on
   arrays that are not lvalues (for example, members of structures returned
   by functions).

   If INDEX is of some user-defined type, it must be converted to
   integer type.  Otherwise, to make a compatible PLUS_EXPR, it
   will inherit the type of the array, which will be some pointer type.
   
   LOC is the location to use in building the array reference.  */

tree
build_array_ref (location_t loc, tree array, tree idx)
{
  tree ret;

  if (idx == 0)
    {
      error_at (loc, "subscript missing in array reference");
      return error_mark_node;
    }

  if (TREE_TYPE (array) == error_mark_node
      || TREE_TYPE (idx) == error_mark_node)
    return error_mark_node;

  /* If ARRAY is a COMPOUND_EXPR or COND_EXPR, move our reference
     inside it.  */
  switch (TREE_CODE (array))
    {
    case COMPOUND_EXPR:
      {
        tree value = build_array_ref (loc, TREE_OPERAND (array, 1), idx);
        ret = build2 (COMPOUND_EXPR, TREE_TYPE (value),
                      TREE_OPERAND (array, 0), value);
        SET_EXPR_LOCATION (ret, loc);
        return ret;
      }

    case COND_EXPR:
      ret = build_conditional_expr
              (TREE_OPERAND (array, 0),
               build_array_ref (loc, TREE_OPERAND (array, 1), idx),
               build_array_ref (loc, TREE_OPERAND (array, 2), idx),
               tf_warning_or_error);
      protected_set_expr_location (ret, loc);
      return ret;

    default:
      break;
    }

  if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
    {
      tree rval, type;

      warn_array_subscript_with_type_char (idx);

      if (!INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (TREE_TYPE (idx)))
        {
          error_at (loc, "array subscript is not an integer");
          return error_mark_node;
        }

      /* Apply integral promotions *after* noticing character types.
         (It is unclear why we do these promotions -- the standard
         does not say that we should.  In fact, the natural thing would
         seem to be to convert IDX to ptrdiff_t; we're performing
         pointer arithmetic.)  */
      idx = perform_integral_promotions (idx);

      /* An array that is indexed by a non-constant
         cannot be stored in a register; we must be able to do
         address arithmetic on its address.
         Likewise an array of elements of variable size.  */
      if (TREE_CODE (idx) != INTEGER_CST
          || (COMPLETE_TYPE_P (TREE_TYPE (TREE_TYPE (array)))
              && (TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))))
                  != INTEGER_CST)))
        {
          if (!cxx_mark_addressable (array))
            return error_mark_node;
        }

      /* An array that is indexed by a constant value which is not within
         the array bounds cannot be stored in a register either; because we
         would get a crash in store_bit_field/extract_bit_field when trying
         to access a non-existent part of the register.  */
      if (TREE_CODE (idx) == INTEGER_CST
          && TYPE_DOMAIN (TREE_TYPE (array))
          && ! int_fits_type_p (idx, TYPE_DOMAIN (TREE_TYPE (array))))
        {
          if (!cxx_mark_addressable (array))
            return error_mark_node;
        }

      if (!lvalue_p (array))
        pedwarn (loc, OPT_pedantic, 
                 "ISO C++ forbids subscripting non-lvalue array");

      /* Note in C++ it is valid to subscript a `register' array, since
         it is valid to take the address of something with that
         storage specification.  */
      if (extra_warnings)
        {
          tree foo = array;
          while (TREE_CODE (foo) == COMPONENT_REF)
            foo = TREE_OPERAND (foo, 0);
          if (TREE_CODE (foo) == VAR_DECL && DECL_REGISTER (foo))
            warning_at (loc, OPT_Wextra,
                        "subscripting array declared %<register%>");
        }

      type = TREE_TYPE (TREE_TYPE (array));
      rval = build4 (ARRAY_REF, type, array, idx, NULL_TREE, NULL_TREE);
      /* Array ref is const/volatile if the array elements are
         or if the array is..  */
      TREE_READONLY (rval)
        |= (CP_TYPE_CONST_P (type) | TREE_READONLY (array));
      TREE_SIDE_EFFECTS (rval)
        |= (CP_TYPE_VOLATILE_P (type) | TREE_SIDE_EFFECTS (array));
      TREE_THIS_VOLATILE (rval)
        |= (CP_TYPE_VOLATILE_P (type) | TREE_THIS_VOLATILE (array));
      ret = require_complete_type (fold_if_not_in_template (rval));
      protected_set_expr_location (ret, loc);
      return ret;
    }

  {
    tree ar = default_conversion (array);
    tree ind = default_conversion (idx);

    /* Put the integer in IND to simplify error checking.  */
    if (TREE_CODE (TREE_TYPE (ar)) == INTEGER_TYPE)
      {
        tree temp = ar;
        ar = ind;
        ind = temp;
      }

    if (ar == error_mark_node)
      return ar;

    if (TREE_CODE (TREE_TYPE (ar)) != POINTER_TYPE)
      {
        error_at (loc, "subscripted value is neither array nor pointer");
        return error_mark_node;
      }
    if (TREE_CODE (TREE_TYPE (ind)) != INTEGER_TYPE)
      {
        error_at (loc, "array subscript is not an integer");
        return error_mark_node;
      }

    warn_array_subscript_with_type_char (idx);

    ret = cp_build_indirect_ref (cp_build_binary_op (input_location,
                                                     PLUS_EXPR, ar, ind,
                                                     tf_warning_or_error),
                                 RO_ARRAY_INDEXING,
                                 tf_warning_or_error);
    protected_set_expr_location (ret, loc);
    return ret;
  }
}
\f
/* Resolve a pointer to member function.  INSTANCE is the object
   instance to use, if the member points to a virtual member.

   This used to avoid checking for virtual functions if basetype
   has no virtual functions, according to an earlier ANSI draft.
   With the final ISO C++ rules, such an optimization is
   incorrect: A pointer to a derived member can be static_cast
   to pointer-to-base-member, as long as the dynamic object
   later has the right member.  */

tree
get_member_function_from_ptrfunc (tree *instance_ptrptr, tree function)
{
  if (TREE_CODE (function) == OFFSET_REF)
    function = TREE_OPERAND (function, 1);

  if (TYPE_PTRMEMFUNC_P (TREE_TYPE (function)))
    {
      tree idx, delta, e1, e2, e3, vtbl, basetype;
      tree fntype = TYPE_PTRMEMFUNC_FN_TYPE (TREE_TYPE (function));

      tree instance_ptr = *instance_ptrptr;
      tree instance_save_expr = 0;
      if (instance_ptr == error_mark_node)
        {
          if (TREE_CODE (function) == PTRMEM_CST)
            {
              /* Extracting the function address from a pmf is only
                 allowed with -Wno-pmf-conversions. It only works for
                 pmf constants.  */
              e1 = build_addr_func (PTRMEM_CST_MEMBER (function));
              e1 = convert (fntype, e1);
              return e1;
            }
          else
            {
              error ("object missing in use of %qE", function);
              return error_mark_node;
            }
        }

      if (TREE_SIDE_EFFECTS (instance_ptr))
        instance_ptr = instance_save_expr = save_expr (instance_ptr);

      if (TREE_SIDE_EFFECTS (function))
        function = save_expr (function);

      /* Start by extracting all the information from the PMF itself.  */
      e3 = pfn_from_ptrmemfunc (function);
      delta = delta_from_ptrmemfunc (function);
      idx = build1 (NOP_EXPR, vtable_index_type, e3);
      switch (TARGET_PTRMEMFUNC_VBIT_LOCATION)
        {
        case ptrmemfunc_vbit_in_pfn:
          e1 = cp_build_binary_op (input_location,
                                   BIT_AND_EXPR, idx, integer_one_node,
                                   tf_warning_or_error);
          idx = cp_build_binary_op (input_location,
                                    MINUS_EXPR, idx, integer_one_node,
                                    tf_warning_or_error);
          break;

        case ptrmemfunc_vbit_in_delta:
          e1 = cp_build_binary_op (input_location,
                                   BIT_AND_EXPR, delta, integer_one_node,
                                   tf_warning_or_error);
          delta = cp_build_binary_op (input_location,
                                      RSHIFT_EXPR, delta, integer_one_node,
                                      tf_warning_or_error);
          break;

        default:
          gcc_unreachable ();
        }

      /* Convert down to the right base before using the instance.  A
         special case is that in a pointer to member of class C, C may
         be incomplete.  In that case, the function will of course be
         a member of C, and no conversion is required.  In fact,
         lookup_base will fail in that case, because incomplete
         classes do not have BINFOs.  */
      basetype = TYPE_METHOD_BASETYPE (TREE_TYPE (fntype));
      if (!same_type_ignoring_top_level_qualifiers_p
          (basetype, TREE_TYPE (TREE_TYPE (instance_ptr))))
        {
          basetype = lookup_base (TREE_TYPE (TREE_TYPE (instance_ptr)),
                                  basetype, ba_check, NULL);
          instance_ptr = build_base_path (PLUS_EXPR, instance_ptr, basetype,
                                          1);
          if (instance_ptr == error_mark_node)
            return error_mark_node;
        }
      /* ...and then the delta in the PMF.  */
      instance_ptr = build2 (POINTER_PLUS_EXPR, TREE_TYPE (instance_ptr),
                             instance_ptr, fold_convert (sizetype, delta));

      /* Hand back the adjusted 'this' argument to our caller.  */
      *instance_ptrptr = instance_ptr;

      /* Next extract the vtable pointer from the object.  */
      vtbl = build1 (NOP_EXPR, build_pointer_type (vtbl_ptr_type_node),
                     instance_ptr);
      vtbl = cp_build_indirect_ref (vtbl, RO_NULL, tf_warning_or_error);
      /* If the object is not dynamic the access invokes undefined
         behavior.  As it is not executed in this case silence the
         spurious warnings it may provoke.  */
      TREE_NO_WARNING (vtbl) = 1;

      /* Finally, extract the function pointer from the vtable.  */
      e2 = fold_build2_loc (input_location,
                        POINTER_PLUS_EXPR, TREE_TYPE (vtbl), vtbl,
                        fold_convert (sizetype, idx));
      e2 = cp_build_indirect_ref (e2, RO_NULL, tf_warning_or_error);
      TREE_CONSTANT (e2) = 1;

      /* When using function descriptors, the address of the
         vtable entry is treated as a function pointer.  */
      if (TARGET_VTABLE_USES_DESCRIPTORS)
        e2 = build1 (NOP_EXPR, TREE_TYPE (e2),
                     cp_build_unary_op (ADDR_EXPR, e2, /*noconvert=*/1,
                                     tf_warning_or_error));

      e2 = fold_convert (TREE_TYPE (e3), e2);
      e1 = build_conditional_expr (e1, e2, e3, tf_warning_or_error);

      /* Make sure this doesn't get evaluated first inside one of the
         branches of the COND_EXPR.  */
      if (instance_save_expr)
        e1 = build2 (COMPOUND_EXPR, TREE_TYPE (e1),
                     instance_save_expr, e1);

      function = e1;
    }
  return function;
}

/* Used by the C-common bits.  */
tree
build_function_call (location_t loc ATTRIBUTE_UNUSED, 
                     tree function, tree params)
{
  return cp_build_function_call (function, params, tf_warning_or_error);
}

/* Used by the C-common bits.  */
tree
build_function_call_vec (location_t loc ATTRIBUTE_UNUSED,
                         tree function, VEC(tree,gc) *params,
                         VEC(tree,gc) *origtypes ATTRIBUTE_UNUSED)
{
  VEC(tree,gc) *orig_params = params;
  tree ret = cp_build_function_call_vec (function, &params,
                                         tf_warning_or_error);

  /* cp_build_function_call_vec can reallocate PARAMS by adding
     default arguments.  That should never happen here.  Verify
     that.  */
  gcc_assert (params == orig_params);

  return ret;
}

/* Build a function call using a tree list of arguments.  */

tree
cp_build_function_call (tree function, tree params, tsubst_flags_t complain)
{
  VEC(tree,gc) *vec;
  tree ret;

  vec = make_tree_vector ();
  for (; params != NULL_TREE; params = TREE_CHAIN (params))
    VEC_safe_push (tree, gc, vec, TREE_VALUE (params));
  ret = cp_build_function_call_vec (function, &vec, complain);
  release_tree_vector (vec);
  return ret;
}

/* Build a function call using a vector of arguments.  PARAMS may be
   NULL if there are no parameters.  This changes the contents of
   PARAMS.  */

tree
cp_build_function_call_vec (tree function, VEC(tree,gc) **params,
                            tsubst_flags_t complain)
{
  tree fntype, fndecl;
  int is_method;
  tree original = function;
  int nargs;
  tree *argarray;
  tree parm_types;
  VEC(tree,gc) *allocated = NULL;
  tree ret;

  /* For Objective-C, convert any calls via a cast to OBJC_TYPE_REF
     expressions, like those used for ObjC messenger dispatches.  */
  if (params != NULL && !VEC_empty (tree, *params))
    function = objc_rewrite_function_call (function,
                                           VEC_index (tree, *params, 0));

  /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
     Strip such NOP_EXPRs, since FUNCTION is used in non-lvalue context.  */
  if (TREE_CODE (function) == NOP_EXPR
      && TREE_TYPE (function) == TREE_TYPE (TREE_OPERAND (function, 0)))
    function = TREE_OPERAND (function, 0);

  if (TREE_CODE (function) == FUNCTION_DECL)
    {
      mark_used (function);
      fndecl = function;

      /* Convert anything with function type to a pointer-to-function.  */
      if (DECL_MAIN_P (function) && (complain & tf_error))
        pedwarn (input_location, OPT_pedantic, 
                 "ISO C++ forbids calling %<::main%> from within program");

      function = build_addr_func (function);
    }
  else
    {
      fndecl = NULL_TREE;

      function = build_addr_func (function);
    }

  if (function == error_mark_node)
    return error_mark_node;

  fntype = TREE_TYPE (function);

  if (TYPE_PTRMEMFUNC_P (fntype))
    {
      if (complain & tf_error)
        error ("must use %<.*%> or %<->*%> to call pointer-to-member "
               "function in %<%E (...)%>, e.g. %<(... ->* %E) (...)%>",
               original, original);
      return error_mark_node;
    }

  is_method = (TREE_CODE (fntype) == POINTER_TYPE
               && TREE_CODE (TREE_TYPE (fntype)) == METHOD_TYPE);

  if (!((TREE_CODE (fntype) == POINTER_TYPE
         && TREE_CODE (TREE_TYPE (fntype)) == FUNCTION_TYPE)
        || is_method
        || TREE_CODE (function) == TEMPLATE_ID_EXPR))
    {
      if (complain & tf_error)
        error ("%qE cannot be used as a function", original);
      return error_mark_node;
    }

  /* fntype now gets the type of function pointed to.  */
  fntype = TREE_TYPE (fntype);
  parm_types = TYPE_ARG_TYPES (fntype);

  if (params == NULL)
    {
      allocated = make_tree_vector ();
      params = &allocated;
    }

  nargs = convert_arguments (parm_types, params, fndecl, LOOKUP_NORMAL,
                             complain);
  if (nargs < 0)
    return error_mark_node;

  argarray = VEC_address (tree, *params);

  /* Check for errors in format strings and inappropriately
     null parameters.  */
  check_function_arguments (TYPE_ATTRIBUTES (fntype), nargs, argarray,
                            parm_types);

  ret = build_cxx_call (function, nargs, argarray);

  if (allocated != NULL)
    release_tree_vector (allocated);

  return ret;
}
\f
/* Subroutine of convert_arguments.
   Warn about wrong number of args are genereted. */

static void
warn_args_num (location_t loc, tree fndecl, bool too_many_p)
{
  if (fndecl)
    {
      if (TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE)
        {
          if (DECL_NAME (fndecl) == NULL_TREE
              || IDENTIFIER_HAS_TYPE_VALUE (DECL_NAME (fndecl)))
            error_at (loc,
                      too_many_p
                      ? G_("too many arguments to constructor %q#D")
                      : G_("too few arguments to constructor %q#D"),
                      fndecl);
          else
            error_at (loc,
                      too_many_p
                      ? G_("too many arguments to member function %q#D")
                      : G_("too few arguments to member function %q#D"),
                      fndecl);
        }
      else
        error_at (loc,
                  too_many_p
                  ? G_("too many arguments to function %q#D")
                  : G_("too few arguments to function %q#D"),
                  fndecl);
      inform (DECL_SOURCE_LOCATION (fndecl),
              "declared here");
    }
  else
    error_at (loc, too_many_p ? G_("too many arguments to function")
                              : G_("too few arguments to function"));
}

/* Convert the actual parameter expressions in the list VALUES to the
   types in the list TYPELIST.  The converted expressions are stored
   back in the VALUES vector.
   If parmdecls is exhausted, or when an element has NULL as its type,
   perform the default conversions.

   NAME is an IDENTIFIER_NODE or 0.  It is used only for error messages.

   This is also where warnings about wrong number of args are generated.

   Returns the actual number of arguments processed (which might be less
   than the length of the vector), or -1 on error.

   In C++, unspecified trailing parameters can be filled in with their
   default arguments, if such were specified.  Do so here.  */

static int
convert_arguments (tree typelist, VEC(tree,gc) **values, tree fndecl,
                   int flags, tsubst_flags_t complain)
{
  tree typetail;
  unsigned int i;

  /* Argument passing is always copy-initialization.  */
  flags |= LOOKUP_ONLYCONVERTING;

  for (i = 0, typetail = typelist;
       i < VEC_length (tree, *values);
       i++)
    {
      tree type = typetail ? TREE_VALUE (typetail) : 0;
      tree val = VEC_index (tree, *values, i);

      if (val == error_mark_node || type == error_mark_node)
        return -1;

      if (type == void_type_node)
        {
          if (complain & tf_error)
            {
              warn_args_num (input_location, fndecl, /*too_many_p=*/true);
              return i;
            }
          else
            return -1;
        }

      /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
         Strip such NOP_EXPRs, since VAL is used in non-lvalue context.  */
      if (TREE_CODE (val) == NOP_EXPR
          && TREE_TYPE (val) == TREE_TYPE (TREE_OPERAND (val, 0))
          && (type == 0 || TREE_CODE (type) != REFERENCE_TYPE))
        val = TREE_OPERAND (val, 0);

      if (type == 0 || TREE_CODE (type) != REFERENCE_TYPE)
        {
          if (TREE_CODE (TREE_TYPE (val)) == ARRAY_TYPE
              || TREE_CODE (TREE_TYPE (val)) == FUNCTION_TYPE
              || TREE_CODE (TREE_TYPE (val)) == METHOD_TYPE)
            val = decay_conversion (val);
        }

      if (val == error_mark_node)
        return -1;

      if (type != 0)
        {
          /* Formal parm type is specified by a function prototype.  */
          tree parmval;

          if (!COMPLETE_TYPE_P (complete_type (type)))
            {
              if (complain & tf_error)
                {
                  if (fndecl)
                    error ("parameter %P of %qD has incomplete type %qT",
                           i, fndecl, type);
                  else
                    error ("parameter %P has incomplete type %qT", i, type);
                }
              parmval = error_mark_node;
            }
          else
            {
              parmval = convert_for_initialization
                (NULL_TREE, type, val, flags,
                 "argument passing", fndecl, i, complain);
              parmval = convert_for_arg_passing (type, parmval);
            }

          if (parmval == error_mark_node)
            return -1;

          VEC_replace (tree, *values, i, parmval);
        }
      else
        {
          if (fndecl && DECL_BUILT_IN (fndecl)
              && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_CONSTANT_P)
            /* Don't do ellipsis conversion for __built_in_constant_p
               as this will result in spurious errors for non-trivial
               types.  */
            val = require_complete_type (val);
          else
            val = convert_arg_to_ellipsis (val);

          VEC_replace (tree, *values, i, val);
        }

      if (typetail)
        typetail = TREE_CHAIN (typetail);
    }

  if (typetail != 0 && typetail != void_list_node)
    {
      /* See if there are default arguments that can be used.  Because
         we hold default arguments in the FUNCTION_TYPE (which is so
         wrong), we can see default parameters here from deduced
         contexts (and via typeof) for indirect function calls.
         Fortunately we know whether we have a function decl to
         provide default arguments in a language conformant
         manner.  */
      if (fndecl && TREE_PURPOSE (typetail)
          && TREE_CODE (TREE_PURPOSE (typetail)) != DEFAULT_ARG)
        {
          for (; typetail != void_list_node; ++i)
            {
              tree parmval
                = convert_default_arg (TREE_VALUE (typetail),
                                       TREE_PURPOSE (typetail),