* cp-tree.h (make_typename_type): Change prototype.

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

/* Build expressions with type checking for C++ compiler.
   Copyright (C) 1987, 88, 89, 92-98, 1999 Free Software Foundation, Inc.
   Hacked by Michael Tiemann (tiemann@cygnus.com)

This file is part of GNU CC.

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

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

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


/* 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.

   There are also routines to build RETURN_STMT nodes and CASE_STMT nodes,
   and to process initializations in declarations (since they work
   like a strange sort of assignment).  */

#include "config.h"
#include "system.h"
#include "tree.h"
#include "rtl.h"
#include "cp-tree.h"
#include "tm_p.h"
#include "flags.h"
#include "output.h"
#include "expr.h"
#include "toplev.h"
#include "defaults.h"

static tree convert_for_assignment PROTO((tree, tree, const char *, tree,
                                          int));
static tree pointer_int_sum PROTO((enum tree_code, tree, tree));
static tree rationalize_conditional_expr PROTO((enum tree_code, tree));
static int comp_target_parms PROTO((tree, tree, int));
static int comp_ptr_ttypes_real PROTO((tree, tree, int));
static int comp_ptr_ttypes_const PROTO((tree, tree));
static int comp_ptr_ttypes_reinterpret PROTO((tree, tree));
static int comp_except_types PROTO((tree, tree, int));
static int comp_array_types PROTO((int (*) (tree, tree, int), tree,
                                   tree, int));
static tree common_base_type PROTO((tree, tree));
#if 0
static tree convert_sequence PROTO((tree, tree));
#endif
static tree lookup_anon_field PROTO((tree, tree));
static tree pointer_diff PROTO((tree, tree, tree));
static tree build_component_addr PROTO((tree, tree));
static tree qualify_type PROTO((tree, tree));
static tree get_delta_difference PROTO((tree, tree, int));
static int comp_cv_target_types PROTO((tree, tree, int));
static void casts_away_constness_r PROTO((tree *, tree *));
static int casts_away_constness PROTO ((tree, tree));
static void maybe_warn_about_returning_address_of_local PROTO ((tree));

/* Return the target type of TYPE, which means return T for:
   T*, T&, T[], T (...), and otherwise, just T.  */

tree
target_type (type)
     tree type;
{
  if (TREE_CODE (type) == REFERENCE_TYPE)
    type = TREE_TYPE (type);
  while (TREE_CODE (type) == POINTER_TYPE
         || TREE_CODE (type) == ARRAY_TYPE
         || TREE_CODE (type) == FUNCTION_TYPE
         || TREE_CODE (type) == METHOD_TYPE
         || TREE_CODE (type) == OFFSET_TYPE)
    type = TREE_TYPE (type);
  return type;
}

/* 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 (value)
     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);

  /* First, detect a valid value with a complete type.  */
  if (TYPE_SIZE (type) != 0
      && TYPE_SIZE (type) != size_zero_node)
    return value;

  /* If we see X::Y, we build an OFFSET_TYPE which has
     not been laid out.  Try to avoid an error by interpreting
     it as this->X::Y, if reasonable.  */
  if (TREE_CODE (value) == OFFSET_REF
      && current_class_ref != 0
      && TREE_OPERAND (value, 0) == current_class_ref)
    {
      tree base, member = TREE_OPERAND (value, 1);
      tree basetype = TYPE_OFFSET_BASETYPE (type);
      my_friendly_assert (TREE_CODE (member) == FIELD_DECL, 305);
      base = convert_pointer_to (basetype, current_class_ptr);
      value = build (COMPONENT_REF, TREE_TYPE (member),
                     build_indirect_ref (base, NULL_PTR), member);
      return require_complete_type (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 (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 || TYPE_SIZE (type) != NULL_TREE)
    ;
  else if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
    {
      tree t = complete_type (TREE_TYPE (type));
      if (TYPE_SIZE (t) != NULL_TREE && ! processing_template_decl)
        layout_type (type);
      TYPE_NEEDS_CONSTRUCTING (type)
        = TYPE_NEEDS_CONSTRUCTING (TYPE_MAIN_VARIANT (t));
      TYPE_NEEDS_DESTRUCTOR (type)
        = TYPE_NEEDS_DESTRUCTOR (TYPE_MAIN_VARIANT (t));
    }
  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 (type, value)
     tree type;
     tree value;
{
  type = complete_type (type);
  if (type == error_mark_node)
    /* We already issued an error.  */
    return NULL_TREE;
  else if (!TYPE_SIZE (type) || TYPE_SIZE (type) == size_zero_node)
    {
      incomplete_type_error (value, type);
      return NULL_TREE;
    }
  else
    return type;
}

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

int
type_unknown_p (exp)
     tree exp;
{
  return (TREE_CODE (exp) == OVERLOAD
          || TREE_CODE (exp) == TREE_LIST
          || TREE_TYPE (exp) == unknown_type_node
          || (TREE_CODE (TREE_TYPE (exp)) == OFFSET_TYPE
              && TREE_TYPE (TREE_TYPE (exp)) == unknown_type_node));
}

/* Return truthvalue of whether T is function (or pfn) type.  */

int
fntype_p (t)
     tree t;
{
  return (TREE_CODE (t) == FUNCTION_TYPE || TREE_CODE (t) == METHOD_TYPE
          || (TREE_CODE (t) == POINTER_TYPE
              && (TREE_CODE (TREE_TYPE (t)) == FUNCTION_TYPE
                  || TREE_CODE (TREE_TYPE (t)) == METHOD_TYPE)));
}

/* Return a variant of TYPE which has all the type qualifiers of LIKE
   as well as those of TYPE.  */

static tree
qualify_type (type, like)
     tree type, like;
{
  /* @@ Must do member pointers here.  */
  return cp_build_qualified_type (type, (CP_TYPE_QUALS (type) 
                                         | CP_TYPE_QUALS (like)));
}
\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.  */

tree
commonparms (p1, p2)
     tree p1, p2;
{
  tree oldargs = p1, newargs, n;
  int i, len;
  int any_change = 0;
  char *first_obj = (char *) oballoc (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) = common_type (TREE_VALUE (p1), TREE_VALUE (p2));
        }
      else
        TREE_VALUE (n) = TREE_VALUE (p1);
    }
  if (! any_change)
    {
      obfree (first_obj);
      return oldargs;
    }

  return newargs;
}

/* Given a type, perhaps copied for a typedef,
   find the "original" version of it.  */
tree
original_type (t)
     tree t;
{
  while (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 t;
}

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

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

  /* FIXME: Attributes.  */
  my_friendly_assert (ARITHMETIC_TYPE_P (t1) 
                      || TREE_CODE (t1) == ENUMERAL_TYPE,
                      19990725);
  my_friendly_assert (ARITHMETIC_TYPE_P (t2) 
                      || TREE_CODE (t2) == ENUMERAL_TYPE,
                      19990725);

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

  /* 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);

  /* Perform the integral promotions.  */
  if (code1 != REAL_TYPE)
    {
      t1 = type_promotes_to (t1);
      t2 = type_promotes_to (t2);
    }

  /* 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);

  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 = ((TREE_UNSIGNED (t1) || TREE_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 = ((TREE_UNSIGNED (t1) || TREE_UNSIGNED (t2))
                    ? long_unsigned_type_node : long_integer_type_node);
          return build_type_attribute_variant (t, attributes);
        }
      /* Otherwise prefer the unsigned one.  */
      if (TREE_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);
      else 
        return build_type_attribute_variant (float_type_node,
                                             attributes);
    }
}

/* Return the composite pointer type (see [expr.rel]) for T1 and T2.
   ARG1 and ARG2 are the values with those types.  The LOCATION is a
   string describing the current location, in case an error occurs.  */

tree 
composite_pointer_type (t1, t2, arg1, arg2, location)
     tree t1;
     tree t2;
     tree arg1;
     tree arg2;
     const char* location;
{
  tree result_type;

  /* [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;
 
  /* Deal with pointer-to-member functions in the same way as we deal
     with pointers to functions. */
  if (TYPE_PTRMEMFUNC_P (t1))
    t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
  if (TYPE_PTRMEMFUNC_P (t2))
    t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);
  
  if (comp_target_types (t1, t2, 1))
    result_type = common_type (t1, t2);
  else if (TYPE_MAIN_VARIANT (TREE_TYPE (t1)) == void_type_node)
    {
      if (pedantic && TREE_CODE (t2) == FUNCTION_TYPE)
        pedwarn ("ANSI C++ forbids %s between `void *' and function pointer",
                 location);
      result_type = qualify_type (t1, t2);
    }
  else if (TYPE_MAIN_VARIANT (TREE_TYPE (t2)) == void_type_node)
    {
      if (pedantic && TREE_CODE (t1) == FUNCTION_TYPE)
        pedwarn ("ANSI C++ forbids %s between `void *' and function pointer",
                 location);
      result_type = qualify_type (t2, t1);
    }
  /* C++ */
  else if (same_or_base_type_p (t2, t1))
    result_type = t2;
  else if (IS_AGGR_TYPE (TREE_TYPE (t1))
           && IS_AGGR_TYPE (TREE_TYPE (t2))
           && (result_type = common_base_type (TREE_TYPE (t1),
                                               TREE_TYPE (t2))))
    {
      if (result_type == error_mark_node)
        {
          cp_error ("common base type of types `%T' and `%T' is ambiguous",
                    TREE_TYPE (t1), TREE_TYPE (t2));
          result_type = ptr_type_node;
        }
      else
        {
          if (pedantic
              && result_type != TREE_TYPE (t1)
              && result_type != TREE_TYPE (t2))
            cp_pedwarn ("`%T' and `%T' converted to `%T *' in %s",
                        t1, t2, result_type, location);
          
          result_type = build_pointer_type (result_type);
        }
    }
  else
    {
      cp_pedwarn ("pointer type mismatch in %s", location);
      result_type = ptr_type_node;
    }

  return result_type;
}

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

   This is the type for the result of most arithmetic operations
   if the operands have the given two types.

   We do not deal with enumeral types here because they have already been
   converted to integer types.  */

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

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

  if ((ARITHMETIC_TYPE_P (t1) || TREE_CODE (t1) == ENUMERAL_TYPE)
      && (ARITHMETIC_TYPE_P (t2) || TREE_CODE (t2) == ENUMERAL_TYPE))
    return type_after_usual_arithmetic_conversions (t1, t2);

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

  /* Treat an enum type as the unsigned integer type of the same width.  */

  if (TREE_CODE (t1) == ENUMERAL_TYPE)
    t1 = type_for_size (TYPE_PRECISION (t1), 1);
  if (TREE_CODE (t2) == ENUMERAL_TYPE)
    t2 = type_for_size (TYPE_PRECISION (t2), 1);

  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 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 = common_type (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);
    }

  switch (code1)
    {
    case INTEGER_TYPE:
    case REAL_TYPE:
      /* We should have called type_after_usual_arithmetic_conversions
         above.  */
      my_friendly_abort (19990725);
      break;

    case POINTER_TYPE:
    case REFERENCE_TYPE:
      /* For two pointers, do this recursively on the target type,
         and combine the qualifiers of the two types' targets.  */
      /* This code was turned off; I don't know why.
         But ANSI C++ specifies doing this with the qualifiers.
         So I turned it on again.  */
      {
        tree tt1 = TREE_TYPE (t1);
        tree tt2 = TREE_TYPE (t2);
        tree b1, b2;
        int type_quals;
        tree target;

        if (TREE_CODE (tt1) == OFFSET_TYPE)
          {
            b1 = TYPE_OFFSET_BASETYPE (tt1);
            b2 = TYPE_OFFSET_BASETYPE (tt2);
            tt1 = TREE_TYPE (tt1);
            tt2 = TREE_TYPE (tt2);
          }
        else
          b1 = b2 = NULL_TREE;

        type_quals = (CP_TYPE_QUALS (tt1) | CP_TYPE_QUALS (tt2));
        tt1 = TYPE_MAIN_VARIANT (tt1);
        tt2 = TYPE_MAIN_VARIANT (tt2);

        if (tt1 == tt2)
          target = tt1;
        else if (tt1 == void_type_node || tt2 == void_type_node)
          target = void_type_node;
        else if (tt1 == unknown_type_node)
          target = tt2;
        else if (tt2 == unknown_type_node)
          target = tt1;
        else
          target = common_type (tt1, tt2);

        target = cp_build_qualified_type (target, type_quals);

        if (b1)
          {
            if (same_type_p (b1, b2)
                || (DERIVED_FROM_P (b1, b2) && binfo_or_else (b1, b2)))
              target = build_offset_type (b2, target);
            else if (binfo_or_else (b2, b1))
              target = build_offset_type (b1, target);
          }

        if (code1 == POINTER_TYPE)
          t1 = build_pointer_type (target);
        else
          t1 = build_reference_type (target);
        t1 = build_type_attribute_variant (t1, attributes);

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

        return t1;
      }

    case ARRAY_TYPE:
      {
        tree elt = common_type (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));
        return build_type_attribute_variant (t1, attributes);
      }

    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 = common_type (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 build_type_attribute_variant (t1, attributes);
        if (valtype == TREE_TYPE (t2) && ! p1)
          return 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 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 build_type_attribute_variant (rval, attributes);
          }

        rval = build_function_type (valtype, commonparms (p1, p2));
        rval = build_exception_variant (rval, raises);
        return build_type_attribute_variant (rval, attributes);
      }

    case RECORD_TYPE:
    case UNION_TYPE:
      t1 = TYPE_MAIN_VARIANT (t1);
      t2 = TYPE_MAIN_VARIANT (t2);

      if (DERIVED_FROM_P (t1, t2) && binfo_or_else (t1, t2))
        return build_type_attribute_variant (t1, attributes);
      else if (binfo_or_else (t2, t1))
        return build_type_attribute_variant (t2, attributes);
      else
        {
          compiler_error ("common_type called with uncommon aggregate types");
          return error_mark_node;
        }

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

          tree b1 = TYPE_OFFSET_BASETYPE (t1);
          tree b2 = TYPE_OFFSET_BASETYPE (t2);

          if (same_type_p (b1, b2)
              || (DERIVED_FROM_P (b1, b2) && binfo_or_else (b1, b2)))
            basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t2)));
          else
            {
              if (binfo_or_else (b2, b1) == NULL_TREE)
                compiler_error ("common_type called with uncommon method types");
              basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t1)));
            }

          raises = TYPE_RAISES_EXCEPTIONS (t1);

          /* 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 = common_type (t1, t2);
          t3 = build_cplus_method_type (basetype, TREE_TYPE (t3),
                                        TYPE_ARG_TYPES (t3));
          t1 = build_exception_variant (t3, raises);
        }
      else
        compiler_error ("common_type called with uncommon method types");

      return build_type_attribute_variant (t1, attributes);

    case OFFSET_TYPE:
      /* Pointers to members should now be handled by the POINTER_TYPE
         case above.  */
      my_friendly_abort (990325);

    default:
      return build_type_attribute_variant (t1, attributes);
    }
}
\f
/* Compare two exception specifier types for exactness or subsetness, if
   allowed. Returns 0 for mismatch, 1 for same, 2 if B is allowed by A.
 
   [except.spec] "If a class X ... objects of class X or any class publicly
   and unambigously derrived from X. Similarly, if a pointer type Y * ...
   exceptions of type Y * or that are pointers to any type publicly and
   unambigously derrived 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 int
comp_except_types (a, b, exact)
     tree a, b;
     int exact;
{
  if (same_type_p (a, b))
    return 1;
  else if (!exact)
    {
      if (CP_TYPE_QUALS (a) || CP_TYPE_QUALS (b))
        return 0;
      
      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 0;
        }
      
      if (TREE_CODE (a) != RECORD_TYPE
          || TREE_CODE (b) != RECORD_TYPE)
        return 0;
      
      if (ACCESSIBLY_UNIQUELY_DERIVED_P (a, b))
        return 2;
    }
  return 0;
}

/* Return 1 if TYPE1 and TYPE2 are equivalent exception specifiers.
   If EXACT is 0, T2 can be a subset of 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.  */

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

  if (t1 == t2)
    return 1;
  
  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 0;
  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 0;
    }
  return !exact || base == NULL_TREE || length == list_length (t1);
}

/* Compare the array types T1 and T2, using CMP as the type comparison
   function for the element types.  STRICT is as for comptypes.  */

static int
comp_array_types (cmp, t1, t2, strict)
     register int (*cmp) PROTO((tree, tree, int));
     tree t1, t2;
     int strict;
{
  tree d1;
  tree d2;

  if (t1 == t2)
    return 1;

  /* The type of the array elements must be the same.  */
  if (!(TREE_TYPE (t1) == TREE_TYPE (t2)
        || (*cmp) (TREE_TYPE (t1), TREE_TYPE (t2), 
                   strict & ~COMPARE_REDECLARATION)))
    return 0;

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

  if (d1 == d2)
    return 1;

  /* If one of the arrays is dimensionless, and the other has a
     dimension, they are of different types.  However, it is legal 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 strict & COMPARE_REDECLARATION;

  /* Check that the dimensions are the same.  */
  return (cp_tree_equal (TYPE_MIN_VALUE (d1),
                         TYPE_MIN_VALUE (d2))
          && cp_tree_equal (TYPE_MAX_VALUE (d1),
                            TYPE_MAX_VALUE (d2)));
}

/* Return 1 if T1 and T2 are compatible types for assignment or
   various other operations.  STRICT is a bitwise-or of the COMPARE_*
   flags.  */

int
comptypes (t1, t2, strict)
     tree t1;
     tree t2;
     int strict;
{
  int attrval, val;
  int orig_strict = strict;

  /* The special exemption for redeclaring array types without an
     array bound only applies at the top level:

       extern int (*i)[];
       int (*i)[8];

     is not legal, for example.  */
  strict &= ~COMPARE_REDECLARATION;

  /* Suppress errors caused by previously reported errors */
  if (t1 == t2)
    return 1;

  /* This should never happen.  */
  my_friendly_assert (t1 != error_mark_node, 307);

  if (t2 == error_mark_node)
    return 0;

  if (strict & COMPARE_RELAXED)
    {
      /* Treat an enum type as the unsigned integer type of the same width.  */

      if (TREE_CODE (t1) == ENUMERAL_TYPE)
        t1 = type_for_size (TYPE_PRECISION (t1), 1);
      if (TREE_CODE (t2) == ENUMERAL_TYPE)
        t2 = type_for_size (TYPE_PRECISION (t2), 1);

      if (t1 == t2)
        return 1;
    }

  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 0;

  /* Qualifiers must match.  */
  if (CP_TYPE_QUALS (t1) != CP_TYPE_QUALS (t2))
    return 0;
  if (strict == COMPARE_STRICT 
      && TYPE_FOR_JAVA (t1) != TYPE_FOR_JAVA (t2))
    return 0;

  /* 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 (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
    return 1;

  /* ??? COMP_TYPE_ATTRIBUTES is currently useless for variables as each
     attribute is its own main variant (`val' will remain 0).  */
#ifndef COMP_TYPE_ATTRIBUTES
#define COMP_TYPE_ATTRIBUTES(t1,t2)     1
#endif

  if (strict & COMPARE_NO_ATTRIBUTES)
    attrval = 1;
  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  else if (! (attrval = COMP_TYPE_ATTRIBUTES (t1, t2)))
     return 0;

  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  val = 0;

  switch (TREE_CODE (t1))
    {
    case TEMPLATE_TEMPLATE_PARM:
      if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
          || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2))
        return 0;
      if (! comp_template_parms (DECL_TEMPLATE_PARMS (TYPE_NAME (t1)),
                                 DECL_TEMPLATE_PARMS (TYPE_NAME (t2))))
        return 0;
      if (!TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (t1) 
          && ! TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (t2))
        return 1;
      /* 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) == TEMPLATE_TEMPLATE_PARM))
        val = comp_template_args (TYPE_TI_ARGS (t1),
                                  TYPE_TI_ARGS (t2));
    look_hard:
      if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
        val = 1;
      else if ((strict & COMPARE_RELAXED) && DERIVED_FROM_P (t2, t1))
        val = 1;
      break;

    case OFFSET_TYPE:
      val = (comptypes (build_pointer_type (TYPE_OFFSET_BASETYPE (t1)),
                        build_pointer_type (TYPE_OFFSET_BASETYPE (t2)), strict)
             && comptypes (TREE_TYPE (t1), TREE_TYPE (t2), strict));
      break;

    case METHOD_TYPE:
      if (! comp_except_specs (TYPE_RAISES_EXCEPTIONS (t1),
                               TYPE_RAISES_EXCEPTIONS (t2), 1))
        return 0;

      /* This case is anti-symmetrical!
         One can pass a base member (or member function)
         to something expecting a derived member (or member function),
         but not vice-versa!  */

      val = (comptypes (TREE_TYPE (t1), TREE_TYPE (t2), strict)
             && compparms (TYPE_ARG_TYPES (t1), TYPE_ARG_TYPES (t2)));
      break;

    case POINTER_TYPE:
    case REFERENCE_TYPE:
      t1 = TREE_TYPE (t1);
      t2 = TREE_TYPE (t2);
      /* first, check whether the referred types match with the
         required level of strictness */
      val = comptypes (t1, t2, strict);
      if (val)
        break;
      if (TREE_CODE (t1) == RECORD_TYPE 
          && TREE_CODE (t2) == RECORD_TYPE)
        goto look_hard;
      break;

    case FUNCTION_TYPE:
      if (! comp_except_specs (TYPE_RAISES_EXCEPTIONS (t1),
                               TYPE_RAISES_EXCEPTIONS (t2), 1))
        return 0;

      val = ((TREE_TYPE (t1) == TREE_TYPE (t2)
              || comptypes (TREE_TYPE (t1), TREE_TYPE (t2), strict))
             && compparms (TYPE_ARG_TYPES (t1), TYPE_ARG_TYPES (t2)));
      break;

    case ARRAY_TYPE:
      /* Target types must match incl. qualifiers.  We use ORIG_STRICT
         here since this is the one place where
         COMPARE_REDECLARATION should be used.  */
      val = comp_array_types (comptypes, t1, t2, orig_strict);
      break;

    case TEMPLATE_TYPE_PARM:
      return TEMPLATE_TYPE_IDX (t1) == TEMPLATE_TYPE_IDX (t2)
        && TEMPLATE_TYPE_LEVEL (t1) == TEMPLATE_TYPE_LEVEL (t2);

    case TYPENAME_TYPE:
      if (TYPE_IDENTIFIER (t1) != TYPE_IDENTIFIER (t2))
        return 0;
      return same_type_p (TYPE_CONTEXT (t1), TYPE_CONTEXT (t2));

    case COMPLEX_TYPE:
      return same_type_p (TREE_TYPE (t1), TREE_TYPE (t2));

    default:
      break;
    }
  return attrval == 2 && val == 1 ? 2 : val;
}

/* Subroutine of comp_target-types.  Make sure that the cv-quals change
   only in the same direction as the target type.  */

static int
comp_cv_target_types (ttl, ttr, nptrs)
     tree ttl, ttr;
     int nptrs;
{
  int t;

  if (!at_least_as_qualified_p (ttl, ttr)
      && !at_least_as_qualified_p (ttr, ttl))
    /* The qualifications are incomparable.  */
    return 0;

  if (TYPE_MAIN_VARIANT (ttl) == TYPE_MAIN_VARIANT (ttr))
    return more_qualified_p (ttr, ttl) ? -1 : 1;

  t = comp_target_types (ttl, ttr, nptrs);
  if ((t == 1 && at_least_as_qualified_p (ttl, ttr)) 
      || (t == -1 && at_least_as_qualified_p (ttr, ttl)))
    return t;

  return 0;
}

/* Return 1 or -1 if TTL and TTR are pointers to types that are equivalent,
   ignoring their qualifiers, 0 if not. Return 1 means that TTR can be
   converted to TTL. Return -1 means that TTL can be converted to TTR but
   not vice versa.

   NPTRS is the number of pointers we can strip off and keep cool.
   This is used to permit (for aggr A, aggr B) A, B* to convert to A*,
   but to not permit B** to convert to A**.

   This should go away.  Callers should use can_convert or something
   similar instead.  (jason 17 Apr 1997)  */

int
comp_target_types (ttl, ttr, nptrs)
     tree ttl, ttr;
     int nptrs;
{
  ttl = TYPE_MAIN_VARIANT (ttl);
  ttr = TYPE_MAIN_VARIANT (ttr);
  if (same_type_p (ttl, ttr))
    return 1;

  if (TREE_CODE (ttr) != TREE_CODE (ttl))
    return 0;

  if ((TREE_CODE (ttr) == POINTER_TYPE
       || TREE_CODE (ttr) == REFERENCE_TYPE)
      /* If we get a pointer with nptrs == 0, we don't allow any tweaking
         of the type pointed to.  This is necessary for reference init
         semantics.  We won't get here from a previous call with nptrs == 1;
         for multi-level pointers we end up in comp_ptr_ttypes.  */
      && nptrs > 0)
    {
      int is_ptr = TREE_CODE (ttr) == POINTER_TYPE;

      ttl = TREE_TYPE (ttl);
      ttr = TREE_TYPE (ttr);

      if (is_ptr)
        {
          if (TREE_CODE (ttl) == UNKNOWN_TYPE
              || TREE_CODE (ttr) == UNKNOWN_TYPE)
            return 1;
          else if (TREE_CODE (ttl) == VOID_TYPE
                   && TREE_CODE (ttr) != FUNCTION_TYPE
                   && TREE_CODE (ttr) != METHOD_TYPE
                   && TREE_CODE (ttr) != OFFSET_TYPE)
            return 1;
          else if (TREE_CODE (ttr) == VOID_TYPE
                   && TREE_CODE (ttl) != FUNCTION_TYPE
                   && TREE_CODE (ttl) != METHOD_TYPE
                   && TREE_CODE (ttl) != OFFSET_TYPE)
            return -1;
          else if (TREE_CODE (ttl) == POINTER_TYPE
                   || TREE_CODE (ttl) == ARRAY_TYPE)
            {
              if (comp_ptr_ttypes (ttl, ttr))
                return 1;
              else if (comp_ptr_ttypes (ttr, ttl))
                return -1;
              return 0;
            }
        }

      /* Const and volatile mean something different for function types,
         so the usual checks are not appropriate.  */
      if (TREE_CODE (ttl) == FUNCTION_TYPE || TREE_CODE (ttl) == METHOD_TYPE)
        return comp_target_types (ttl, ttr, nptrs - 1);

      return comp_cv_target_types (ttl, ttr, nptrs - 1);
    }

  if (TREE_CODE (ttr) == ARRAY_TYPE)
    return comp_array_types (comp_target_types, ttl, ttr, COMPARE_STRICT);
  else if (TREE_CODE (ttr) == FUNCTION_TYPE || TREE_CODE (ttr) == METHOD_TYPE)
    {
      tree argsl, argsr;
      int saw_contra = 0;

      if (pedantic)
        {
          if (!same_type_p (TREE_TYPE (ttl), TREE_TYPE (ttr)))
            return 0;
        }
      else
        {
          switch (comp_target_types (TREE_TYPE (ttl), TREE_TYPE (ttr), -1))
            {
            case 0:
              return 0;
            case -1:
              saw_contra = 1;
            }
        }

      argsl = TYPE_ARG_TYPES (ttl);
      argsr = TYPE_ARG_TYPES (ttr);

      /* Compare 'this' here, not in comp_target_parms.  */
      if (TREE_CODE (ttr) == METHOD_TYPE)
        {
          tree tl = TYPE_METHOD_BASETYPE (ttl);
          tree tr = TYPE_METHOD_BASETYPE (ttr);

          if (!same_or_base_type_p (tr, tl))
            {
              if (same_or_base_type_p (tl, tr))
                saw_contra = 1;
              else
                return 0;
            }

          argsl = TREE_CHAIN (argsl);
          argsr = TREE_CHAIN (argsr);
        }

        switch (comp_target_parms (argsl, argsr, 1))
          {
          case 0:
            return 0;
          case -1:
            saw_contra = 1;
          }

        return saw_contra ? -1 : 1;
    }
  /* for C++ */
  else if (TREE_CODE (ttr) == OFFSET_TYPE)
    {
      int base;

      /* Contravariance: we can assign a pointer to base member to a pointer
         to derived member.  Note difference from simple pointer case, where
         we can pass a pointer to derived to a pointer to base.  */
      if (same_or_base_type_p (TYPE_OFFSET_BASETYPE (ttr),
                               TYPE_OFFSET_BASETYPE (ttl)))
        base = 1;
      else if (same_or_base_type_p (TYPE_OFFSET_BASETYPE (ttl),
                                    TYPE_OFFSET_BASETYPE (ttr)))
        {
          tree tmp = ttl;
          ttl = ttr;
          ttr = tmp;
          base = -1;
        }
      else
        return 0;

      ttl = TREE_TYPE (ttl);
      ttr = TREE_TYPE (ttr);

      if (TREE_CODE (ttl) == POINTER_TYPE
          || TREE_CODE (ttl) == ARRAY_TYPE)
        {
          if (comp_ptr_ttypes (ttl, ttr))
            return base;
          return 0;
        }
      else
        {
          if (comp_cv_target_types (ttl, ttr, nptrs) == 1)
            return base;
          return 0;
        }
    }
  else if (IS_AGGR_TYPE (ttl))
    {
      if (nptrs < 0)
        return 0;
      if (same_or_base_type_p (build_pointer_type (ttl), 
                               build_pointer_type (ttr)))
        return 1;
      if (same_or_base_type_p (build_pointer_type (ttr), 
                               build_pointer_type (ttl)))
        return -1;
      return 0;
    }

  return 0;
}

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

int
at_least_as_qualified_p (type1, type2)
     tree type1;
     tree type2;
{
  /* All qualifiers for TYPE2 must also appear in TYPE1.  */
  return ((CP_TYPE_QUALS (type1) & CP_TYPE_QUALS (type2))
          == CP_TYPE_QUALS (type2));
}

/* Returns 1 if TYPE1 is more qualified than TYPE2.  */

int
more_qualified_p (type1, type2)
     tree type1;
     tree type2;
{
  return (CP_TYPE_QUALS (type1) != CP_TYPE_QUALS (type2)
          && at_least_as_qualified_p (type1, type2));
}

/* 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 (type1, type2)
     tree type1;
     tree type2;
{
  if (CP_TYPE_QUALS (type1) == CP_TYPE_QUALS (type2))
    return 0;

  if (at_least_as_qualified_p (type1, type2))
    return 1;

  else if (at_least_as_qualified_p (type2, type1))
    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 (type1, type2)
     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;
}

/* If two types share a common base type, return that basetype.
   If there is not a unique most-derived base type, this function
   returns ERROR_MARK_NODE.  */

static tree
common_base_type (tt1, tt2)
     tree tt1, tt2;
{
  tree best = NULL_TREE;
  int i;

  /* If one is a baseclass of another, that's good enough.  */
  if (UNIQUELY_DERIVED_FROM_P (tt1, tt2))
    return tt1;
  if (UNIQUELY_DERIVED_FROM_P (tt2, tt1))
    return tt2;

  /* Otherwise, try to find a unique baseclass of TT1
     that is shared by TT2, and follow that down.  */
  for (i = CLASSTYPE_N_BASECLASSES (tt1)-1; i >= 0; i--)
    {
      tree basetype = TYPE_BINFO_BASETYPE (tt1, i);
      tree trial = common_base_type (basetype, tt2);
      if (trial)
        {
          if (trial == error_mark_node)
            return trial;
          if (best == NULL_TREE)
            best = trial;
          else if (best != trial)
            return error_mark_node;
        }
    }

  /* Same for TT2.  */
  for (i = CLASSTYPE_N_BASECLASSES (tt2)-1; i >= 0; i--)
    {
      tree basetype = TYPE_BINFO_BASETYPE (tt2, i);
      tree trial = common_base_type (tt1, basetype);
      if (trial)
        {
          if (trial == error_mark_node)
            return trial;
          if (best == NULL_TREE)
            best = trial;
          else if (best != trial)
            return error_mark_node;
        }
    }
  return best;
}
\f
/* Subroutines of `comptypes'.  */

/* Return 1 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.

   C++: See comment above about TYPE1, TYPE2.  */

int
compparms (parms1, parms2)
     tree parms1, parms2;
{
  register tree t1 = parms1, t2 = parms2;

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

  while (1)
    {
      if (t1 == 0 && t2 == 0)
        return 1;
      /* If one parmlist is shorter than the other,
         they fail to match.  */
      if (t1 == 0 || t2 == 0)
        return 0;
      if (!same_type_p (TREE_VALUE (t2), TREE_VALUE (t1)))
        return 0;

      t1 = TREE_CHAIN (t1);
      t2 = TREE_CHAIN (t2);
    }
}

/* This really wants return whether or not parameter type lists
   would make their owning functions assignment compatible or not.

   The return value is like for comp_target_types.

   This should go away, possibly with the exception of the empty parmlist
   conversion; there are no conversions between function types in C++.
   (jason 17 Apr 1997)  */

static int
comp_target_parms (parms1, parms2, strict)
     tree parms1, parms2;
     int strict;
{
  register tree t1 = parms1, t2 = parms2;
  int warn_contravariance = 0;

  /* In C, an unspecified parmlist matches any specified parmlist
     whose argument types don't need default promotions.  This is not
     true for C++, but let's do it anyway for unfixed headers.  */

  if (t1 == 0 && t2 != 0)
    {
      if (! flag_strict_prototype && t2 == void_list_node)
        /* t1 might be the arglist of a function pointer in extern "C"
           declared to take (), which we fudged to (...).  Don't make the
           user pay for our mistake.  */;
      else
        cp_pedwarn ("ANSI C++ prohibits conversion from `%#T' to `(...)'",
                    parms2);
      return self_promoting_args_p (t2);
    }
  if (t2 == 0)
    return self_promoting_args_p (t1);

  for (; t1 || t2; t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
    {
      tree p1, p2;

      /* If one parmlist is shorter than the other,
         they fail to match, unless STRICT is <= 0.  */
      if (t1 == 0 || t2 == 0)
        {
          if (strict > 0)
            return 0;
          if (strict < 0)
            return 1 + warn_contravariance;
          return ((t1 && TREE_PURPOSE (t1)) + warn_contravariance);
        }
      p1 = TREE_VALUE (t1);
      p2 = TREE_VALUE (t2);
      if (same_type_p (p1, p2))
        continue;

      if (pedantic)
        return 0;

      if ((TREE_CODE (p1) == POINTER_TYPE && TREE_CODE (p2) == POINTER_TYPE)
          || (TREE_CODE (p1) == REFERENCE_TYPE
              && TREE_CODE (p2) == REFERENCE_TYPE))
        {
          if (strict <= 0
              && (TYPE_MAIN_VARIANT (TREE_TYPE (p1))
                  == TYPE_MAIN_VARIANT (TREE_TYPE (p2))))
            continue;

          /* The following is wrong for contravariance,
             but many programs depend on it.  */
          if (TREE_TYPE (p1) == void_type_node)
            continue;
          if (TREE_TYPE (p2) == void_type_node)
            {
              warn_contravariance = 1;
              continue;
            }
          if (IS_AGGR_TYPE (TREE_TYPE (p1))
              && !same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (p1)),
                               TYPE_MAIN_VARIANT (TREE_TYPE (p2))))
            return 0;
        }
      /* Note backwards order due to contravariance.  */
      if (comp_target_types (p2, p1, 1) <= 0)
        {
          if (comp_target_types (p1, p2, 1) > 0)
            {
              warn_contravariance = 1;
              continue;
            }
          if (strict != 0)
            return 0;
        }
    }
  return warn_contravariance ? -1 : 1;
}
\f
/* Compute the value of the `sizeof' operator.  */

tree
c_sizeof (type)
     tree type;
{
  enum tree_code code = TREE_CODE (type);
  tree t;

  if (processing_template_decl)
    return build_min (SIZEOF_EXPR, sizetype, type);

  if (code == FUNCTION_TYPE)
    {
      if (pedantic || warn_pointer_arith)
        pedwarn ("ANSI C++ forbids taking the sizeof a function type");
      return size_int (1);
    }
  if (code == METHOD_TYPE)
    {
      if (pedantic || warn_pointer_arith)
        pedwarn ("ANSI C++ forbids taking the sizeof a method type");
      return size_int (1);
    }
  if (code == VOID_TYPE)
    {
      if (pedantic || warn_pointer_arith)
        pedwarn ("ANSI C++ forbids taking the sizeof a void type");
      return size_int (1);
    }
  if (code == ERROR_MARK)
    return size_int (1);

  /* ARM $5.3.2: ``When applied to a reference, the result is the size of the
     referenced object.'' */
  if (code == REFERENCE_TYPE)
    type = TREE_TYPE (type);

  if (code == OFFSET_TYPE)
    {
      cp_error ("`sizeof' applied to non-static member");
      return size_int (0);
    }

  if (TYPE_SIZE (complete_type (type)) == 0)
    {
      cp_error ("`sizeof' applied to incomplete type `%T'", type);
      return size_int (0);
    }

  /* Convert in case a char is more than one unit.  */
  t = size_binop (CEIL_DIV_EXPR, TYPE_SIZE (type), 
                  size_int (TYPE_PRECISION (char_type_node)));
  t = convert (sizetype, t);
  /* size_binop does not put the constant in range, so do it now.  */
  if (TREE_CODE (t) == INTEGER_CST && force_fit_type (t, 0))
    TREE_CONSTANT_OVERFLOW (t) = TREE_OVERFLOW (t) = 1;
  return t;
}

tree
expr_sizeof (e)
     tree e;
{
  if (processing_template_decl)
    return build_min (SIZEOF_EXPR, sizetype, e);

  if (TREE_CODE (e) == COMPONENT_REF
      && DECL_C_BIT_FIELD (TREE_OPERAND (e, 1)))
    error ("sizeof applied to a bit-field");
  if (is_overloaded_fn (e))
    {
      pedwarn ("ANSI C++ forbids taking the sizeof a function type");
      return size_int (1);
    }
  else if (type_unknown_p (e))
    {
      incomplete_type_error (e, TREE_TYPE (e));
      return size_int (1);
    }
  /* It's illegal to say `sizeof (X::i)' for `i' a non-static data
     member unless you're in a non-static member of X.  So hand off to
     resolve_offset_ref.  [expr.prim]  */
  else if (TREE_CODE (e) == OFFSET_REF)
    e = resolve_offset_ref (e);

  if (e == error_mark_node)
    return e;

  return c_sizeof (TREE_TYPE (e));
}
  
tree
c_sizeof_nowarn (type)
     tree type;
{
  enum tree_code code = TREE_CODE (type);
  tree t;

  if (code == FUNCTION_TYPE
      || code == METHOD_TYPE
      || code == VOID_TYPE
      || code == ERROR_MARK)
    return size_int (1);
  if (code == REFERENCE_TYPE)
    type = TREE_TYPE (type);

  if (TYPE_SIZE (type) == 0)
    return size_int (0);

  /* Convert in case a char is more than one unit.  */
  t = size_binop (CEIL_DIV_EXPR, TYPE_SIZE (type), 
                  size_int (TYPE_PRECISION (char_type_node)));
  t = convert (sizetype, t);
  force_fit_type (t, 0);
  return t;
}

/* Implement the __alignof keyword: Return the minimum required
   alignment of TYPE, measured in bytes.  */

tree
c_alignof (type)
     tree type;
{
  enum tree_code code = TREE_CODE (type);
  tree t;

  if (processing_template_decl)
    return build_min (ALIGNOF_EXPR, sizetype, type);

  if (code == FUNCTION_TYPE || code == METHOD_TYPE)
    return size_int (FUNCTION_BOUNDARY / BITS_PER_UNIT);

  if (code == VOID_TYPE || code == ERROR_MARK)
    return size_int (1);

  /* C++: this is really correct!  */
  if (code == REFERENCE_TYPE)
    type = TREE_TYPE (type);

  t = size_int (TYPE_ALIGN (type) / BITS_PER_UNIT);
  force_fit_type (t, 0);
  return t;
}
\f
/* Perform the array-to-pointer and function-to-pointer conversions
   for EXP.  

   In addition, references are converted to rvalues and manifest
   constants are replaced by their values.  */

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

  if (TREE_CODE (exp) == OFFSET_REF)
    exp = resolve_offset_ref (exp);

  type = TREE_TYPE (exp);
  code = TREE_CODE (type);

  if (code == REFERENCE_TYPE)
    {
      exp = convert_from_reference (exp);
      type = TREE_TYPE (exp);
      code = TREE_CODE (type);
    }

  /* Constants can be used directly unless they're not loadable.  */
  if (TREE_CODE (exp) == CONST_DECL)
    exp = DECL_INITIAL (exp);
  /* Replace a nonvolatile const static variable with its value.  We
     don't do this for arrays, though; we want the address of the
     first element of the array, not the address of the first element
     of its initializing constant.  We *do* replace variables that the
     user isn't really supposed to know about; this is a hack to deal
     with __PRETTY_FUNCTION__ and the like.  */
  else if (TREE_READONLY_DECL_P (exp)
           && (code != ARRAY_TYPE 
               || (TREE_CODE (exp) == VAR_DECL && DECL_IGNORED_P (exp))))
    {
      exp = decl_constant_value (exp);
      type = TREE_TYPE (exp);
    }

  /* 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.  */

  if (code == VOID_TYPE)
    {
      error ("void value not ignored as it ought to be");
      return error_mark_node;
    }
  if (code == METHOD_TYPE)
    my_friendly_abort (990506);
  if (code == FUNCTION_TYPE || is_overloaded_fn (exp))
    return build_unary_op (ADDR_EXPR, exp, 0);
  if (code == ARRAY_TYPE)
    {
      register tree adr;
      tree ptrtype;

      if (TREE_CODE (exp) == INDIRECT_REF)
        {
          /* Stripping away the INDIRECT_REF is not the right
             thing to do for references...  */
          tree inner = TREE_OPERAND (exp, 0);
          if (TREE_CODE (TREE_TYPE (inner)) == REFERENCE_TYPE)
            {
              inner = build1 (CONVERT_EXPR,
                              build_pointer_type (TREE_TYPE
                                                  (TREE_TYPE (inner))),
                              inner);
              TREE_CONSTANT (inner) = TREE_CONSTANT (TREE_OPERAND (inner, 0));
            }
          return cp_convert (build_pointer_type (TREE_TYPE (type)), inner);
        }

      if (TREE_CODE (exp) == COMPOUND_EXPR)
        {
          tree op1 = decay_conversion (TREE_OPERAND (exp, 1));
          return build (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)
        {
          /* ??? This is not really quite correct
             in that the type of the operand of ADDR_EXPR
             is not the target type of the type of the ADDR_EXPR itself.
             Question is, can this lossage be avoided?  */
          adr = build1 (ADDR_EXPR, ptrtype, exp);
          if (mark_addressable (exp) == 0)
            return error_mark_node;
          TREE_CONSTANT (adr) = staticp (exp);
          TREE_SIDE_EFFECTS (adr) = 0;   /* Default would be, same as EXP.  */
          return adr;
        }
      /* This way is better for a COMPONENT_REF since it can
         simplify the offset for a component.  */
      adr = build_unary_op (ADDR_EXPR, exp, 1);
      return cp_convert (ptrtype, adr);
    }

  /* [basic.lval]: Class rvalues can have cv-qualified types; non-class
     rvalues always have cv-unqualified types.  */
  if (! CLASS_TYPE_P (type))
    exp = cp_convert (TYPE_MAIN_VARIANT (type), exp);

  return exp;
}

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

  exp = decay_conversion (exp);

  type = TREE_TYPE (exp);
  code = TREE_CODE (type);

  if (INTEGRAL_CODE_P (code))
    {
      tree t = type_promotes_to (type);
      if (t != type)
        return cp_convert (t, exp);
    }

  return exp;
}

/* Take the address of an inline function without setting TREE_ADDRESSABLE
   or TREE_USED.  */

tree
inline_conversion (exp)
     tree exp;
{
  if (TREE_CODE (exp) == FUNCTION_DECL)
    exp = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (exp)), exp);

  return exp;
}

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

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

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

  t = TREE_TYPE (totype);
  if (!same_type_p (t, char_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 wchar_t.  */
      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 && warn_write_strings)
    cp_warning ("deprecated conversion from string constant to `%T'", totype);

  return 1;
}
\f
tree
build_object_ref (datum, basetype, field)
     tree datum, basetype, field;
{
  tree dtype;
  if (datum == error_mark_node)
    return error_mark_node;

  dtype = TREE_TYPE (datum);
  if (TREE_CODE (dtype) == REFERENCE_TYPE)
    dtype = TREE_TYPE (dtype);
  if (! IS_AGGR_TYPE_CODE (TREE_CODE (dtype)))
    {
      cp_error ("request for member `%T::%D' in expression of non-aggregate type `%T'",
                basetype, field, dtype);
      return error_mark_node;
    }
  else if (is_aggr_type (basetype, 1))
    {
      tree binfo = binfo_or_else (basetype, dtype);
      if (binfo)
        return build_x_component_ref (build_scoped_ref (datum, basetype),
                                      field, binfo, 1);
    }
  return error_mark_node;
}

/* Like `build_component_ref, but uses an already found field, and converts
   from a reference.  Must compute access for current_class_ref.
   Otherwise, ok.  */

tree
build_component_ref_1 (datum, field, protect)
     tree datum, field;
     int protect;
{
  return convert_from_reference
    (build_component_ref (datum, field, NULL_TREE, protect));
}

/* 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 (code, t)
     enum tree_code code;
     tree t;
{
  /* 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)
    {
      return
        build_conditional_expr (build_x_binary_op ((TREE_CODE (t) == MIN_EXPR
                                                    ? LE_EXPR : GE_EXPR),
                                                   TREE_OPERAND (t, 0),
                                                   TREE_OPERAND (t, 1)),
                            build_unary_op (code, TREE_OPERAND (t, 0), 0),
                            build_unary_op (code, TREE_OPERAND (t, 1), 0));
    }

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

/* 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.  */

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

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

      /* If we find it directly, return the field.  */
      if (DECL_NAME (field) == NULL_TREE
          && type == 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 a COMPONENT_REF for a given DATUM, and it's member COMPONENT.
   COMPONENT can be an IDENTIFIER_NODE that is the name of the member
   that we are interested in, or it can be a FIELD_DECL.  */

tree
build_component_ref (datum, component, basetype_path, protect)
     tree datum, component, basetype_path;
     int protect;
{
  register tree basetype;
  register enum tree_code code;
  register tree field = NULL;
  register tree ref;
  tree field_type;
  int type_quals;

  if (processing_template_decl)
    return build_min_nt (COMPONENT_REF, datum, component);
  
  if (datum == error_mark_node 
      || TREE_TYPE (datum) == error_mark_node)
    return error_mark_node;

  /* BASETYPE holds the type of the class containing the COMPONENT.  */
  basetype = TYPE_MAIN_VARIANT (TREE_TYPE (datum));
    
  /* If DATUM is a COMPOUND_EXPR or COND_EXPR, move our reference
     inside it.  */
  switch (TREE_CODE (datum))
    {
    case COMPOUND_EXPR:
      {
        tree value = build_component_ref (TREE_OPERAND (datum, 1), component,
                                          basetype_path, protect);
        return build (COMPOUND_EXPR, TREE_TYPE (value),
                      TREE_OPERAND (datum, 0), value);
      }
    case COND_EXPR:
      return build_conditional_expr
        (TREE_OPERAND (datum, 0),
         build_component_ref (TREE_OPERAND (datum, 1), component,
                              basetype_path, protect),
         build_component_ref (TREE_OPERAND (datum, 2), component,
                              basetype_path, protect));

    case TEMPLATE_DECL:
      cp_error ("invalid use of %D", datum);
      datum = error_mark_node;
      break;

    default:
      break;
    }

  code = TREE_CODE (basetype);

  if (code == REFERENCE_TYPE)
    {
      datum = convert_from_reference (datum);
      basetype = TYPE_MAIN_VARIANT (TREE_TYPE (datum));
      code = TREE_CODE (basetype);
    }
  if (TREE_CODE (datum) == OFFSET_REF)
    {
      datum = resolve_offset_ref (datum);
      basetype = TYPE_MAIN_VARIANT (TREE_TYPE (datum));
      code = TREE_CODE (basetype);
    }

  /* First, see if there is a field or component with name COMPONENT.  */
  if (TREE_CODE (component) == TREE_LIST)
    {
      /* I could not trigger this code. MvL */
      my_friendly_abort (980326);
#ifdef DEAD
      my_friendly_assert (!(TREE_CHAIN (component) == NULL_TREE
                && DECL_CHAIN (TREE_VALUE (component)) == NULL_TREE), 309);
#endif
      return build (COMPONENT_REF, TREE_TYPE (component), datum, component);
    }

  if (! IS_AGGR_TYPE_CODE (code))
    {
      if (code != ERROR_MARK)
        cp_error ("request for member `%D' in `%E', which is of non-aggregate type `%T'",
                  component, datum, basetype);
      return error_mark_node;
    }

  if (!complete_type_or_else (basetype, datum))
    return error_mark_node;

  if (TREE_CODE (component) == BIT_NOT_EXPR)
    {
      if (TYPE_IDENTIFIER (basetype) != TREE_OPERAND (component, 0))
        {
          cp_error ("destructor specifier `%T::~%T' must have matching names",
                    basetype, TREE_OPERAND (component, 0));
          return error_mark_node;
        }
      if (! TYPE_HAS_DESTRUCTOR (basetype))
        {
          cp_error ("type `%T' has no destructor", basetype);
          return error_mark_node;
        }
      return TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (basetype), 1);
    }

  /* Look up component name in the structure type definition.  */
  if (TYPE_VFIELD (basetype)
      && DECL_NAME (TYPE_VFIELD (basetype)) == component)
    /* Special-case this because if we use normal lookups in an ambiguous
       hierarchy, the compiler will abort (because vptr lookups are
       not supposed to be ambiguous.  */
    field = TYPE_VFIELD (basetype);
  else if (TREE_CODE (component) == FIELD_DECL)
    field = component;
  else if (TREE_CODE (component) == TYPE_DECL)
    {
      cp_error ("invalid use of type decl `%#D' as expression", component);
      return error_mark_node;
    }
  else if (TREE_CODE (component) == TEMPLATE_DECL)
    {
      cp_error ("invalid use of template `%#D' as expression", component);
      return error_mark_node;
    }
  else
    {
      tree name = component;
      if (TREE_CODE (component) == VAR_DECL)
        name = DECL_NAME (component);
      if (TREE_CODE (component) == NAMESPACE_DECL)
        /* Source is in error, but produce a sensible diagnostic.  */
        name = DECL_NAME (component);
      if (basetype_path == NULL_TREE)
        basetype_path = TYPE_BINFO (basetype);
      field = lookup_field (basetype_path, name,
                            protect && !VFIELD_NAME_P (name), 0);
      if (field == error_mark_node)
        return error_mark_node;

      if (field == NULL_TREE)
        {
          /* Not found as a data field, look for it as a method.  If found,
             then if this is the only possible one, return it, else
             report ambiguity error.  */
          tree fndecls = lookup_fnfields (basetype_path, name, 1);
          if (fndecls == error_mark_node)
            return error_mark_node;
          if (fndecls)
            {
              /* If the function is unique and static, we can resolve it
                 now.  Otherwise, we have to wait and see what context it is
                 used in; a component_ref involving a non-static member
                 function can only be used in a call (expr.ref).  */

              if (TREE_CHAIN (fndecls) == NULL_TREE
                  && TREE_CODE (TREE_VALUE (fndecls)) == FUNCTION_DECL)
                {
                  if (DECL_STATIC_FUNCTION_P (TREE_VALUE (fndecls)))
                    {
                      tree fndecl = TREE_VALUE (fndecls);
                      enforce_access (TREE_PURPOSE (fndecls), fndecl);
                      mark_used (fndecl);
                      return fndecl;
                    }
                  else
                    {
                      /* A unique non-static member function.  Other parts
                         of the compiler expect something with
                         unknown_type_node to be really overloaded, so
                         let's oblige.  */
                      TREE_VALUE (fndecls)
                        = scratch_ovl_cons (TREE_VALUE (fndecls), NULL_TREE);
                    }
                }

              ref = build (COMPONENT_REF, unknown_type_node,
                           datum, TREE_VALUE (fndecls));
              return ref;
            }

          cp_error ("`%#T' has no member named `%D'", basetype, name);
          return error_mark_node;
        }
      else if (TREE_TYPE (field) == error_mark_node)
        return error_mark_node;

      if (TREE_CODE (field) != FIELD_DECL)
        {
          if (TREE_CODE (field) == TYPE_DECL)
            cp_pedwarn ("invalid use of type decl `%#D' as expression", field);
          else if (DECL_RTL (field) != 0)
            mark_used (field);
          else
            TREE_USED (field) = 1;
          return field;
        }
    }

  /* See if we have to do any conversions so that we pick up the field from the
     right context.  */
  if (DECL_FIELD_CONTEXT (field) != basetype)
    {
      tree context = DECL_FIELD_CONTEXT (field);
      tree base = context;
      while (!same_type_p (base, basetype) && TYPE_NAME (base)
             && ANON_AGGR_TYPE_P (base))
        {
          base = TYPE_CONTEXT (base);
        }

      /* Handle base classes here...  */
      if (base != basetype && TYPE_USES_COMPLEX_INHERITANCE (basetype))
        {
          tree addr = build_unary_op (ADDR_EXPR, datum, 0);
          if (integer_zerop (addr))
            {
              error ("invalid reference to NULL ptr, use ptr-to-member instead");
              return error_mark_node;
            }
          if (VBASE_NAME_P (DECL_NAME (field)))
            {
              /* It doesn't matter which vbase pointer we grab, just
                 find one of them.  */
              tree binfo = get_binfo (base,
                                      TREE_TYPE (TREE_TYPE (addr)), 0);
              addr = convert_pointer_to_real (binfo, addr);
            }
          else
            addr = convert_pointer_to (base, addr);
          datum = build_indirect_ref (addr, NULL_PTR);
          my_friendly_assert (datum != error_mark_node, 311);
        }
      basetype = base;
 
      /* Handle things from anon unions here...  */
      if (TYPE_NAME (context) && ANON_AGGR_TYPE_P (context))
        {
          tree subfield = lookup_anon_field (basetype, context);
          tree subdatum = build_component_ref (datum, subfield,
                                               basetype_path, protect);
          return build_component_ref (subdatum, field, basetype_path, protect);
        }
    }

  /* Compute the type of the field, as described in [expr.ref].  */
  type_quals = TYPE_UNQUALIFIED;
  field_type = TREE_TYPE (field);
  if (TREE_CODE (field_type) == REFERENCE_TYPE)
    /* The standard says that the type of the result should be the
       type referred to by the reference.  But for now, at least, we
       do the conversion from reference type later.  */
    ;
  else
    {
      type_quals = (CP_TYPE_QUALS (field_type)  
                    | CP_TYPE_QUALS (TREE_TYPE (datum)));

      /* 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_LANG_SPECIFIC (field) && DECL_MUTABLE_P (field))
        type_quals &= ~TYPE_QUAL_CONST;
      field_type = cp_build_qualified_type (field_type, type_quals);
    }

  ref = fold (build (COMPONENT_REF, field_type,
                     break_out_cleanups (datum), field));

  /* 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 (ref) = 1;
  else if (type_quals & TYPE_QUAL_VOLATILE)
    TREE_THIS_VOLATILE (ref) = 1;

  return ref;
}

/* Variant of build_component_ref for use in expressions, which should
   never have REFERENCE_TYPE.  */

tree
build_x_component_ref (datum, component, basetype_path, protect)
     tree datum, component, basetype_path;
     int protect;
{
  tree t = build_component_ref (datum, component, basetype_path, protect);

  if (! processing_template_decl)
    t = convert_from_reference (t);

  return t;
}
\f
/* 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 (ptr, errorstring)
     tree ptr;
     const char *errorstring;
{
  tree rval;

  if (processing_template_decl)
    return build_min_nt (INDIRECT_REF, ptr);

  rval = build_opfncall (INDIRECT_REF, LOOKUP_NORMAL, ptr, NULL_TREE,
                         NULL_TREE);
  if (rval)
    return rval;
  return build_indirect_ref (ptr, errorstring);
}

tree
build_indirect_ref (ptr, errorstring)
     tree ptr;
     const char *errorstring;
{
  register 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 : default_conversion (ptr));
  type = TREE_TYPE (pointer);

  if (TYPE_PTR_P (type) || TREE_CODE (type) == REFERENCE_TYPE)
    {
      /* [expr.unary.op]
         
         If the type of the expression is "pointer to T," the type
         of  the  result  is  "T."   

         We must use the canonical variant because certain parts of
         the back end, like fold, do pointer comparisons between
         types.  */
      tree t = canonical_type_variant (TREE_TYPE (type));

      if (same_type_p (TYPE_MAIN_VARIANT (t), void_type_node))
        {
          /* A pointer to incomplete type (other than cv void) can be
             dereferenced [expr.unary.op]/1  */
          cp_error ("`%T' is not a pointer-to-object type", type);
          return error_mark_node;
        }
      else if (TREE_CODE (pointer) == ADDR_EXPR
          && !flag_volatile
          && 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)
               || flag_volatile);
          return ref;
        }
    }
  /* `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_PTRMEM_P (type) || TYPE_PTRMEMFUNC_P (type))
    error ("invalid use of `%s' on pointer to member", errorstring);
  else if (pointer != error_mark_node)
    {
      if (errorstring)
        error ("invalid type argument of `%s'", errorstring);
      else
        error ("invalid type argument");
    }
  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.  */

tree
build_array_ref (array, idx)
     tree array, idx;
{
  if (idx == 0)
    {
      error ("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 (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE
      && TREE_CODE (array) != INDIRECT_REF)
    {
      tree rval, type;

      /* Subscripting with type char is likely to lose
         on a machine where chars are signed.
         So warn on any machine, but optionally.
         Don't warn for unsigned char since that type is safe.
         Don't warn for signed char because anyone who uses that
         must have done so deliberately.  */
      if (warn_char_subscripts
          && TYPE_MAIN_VARIANT (TREE_TYPE (idx)) == char_type_node)
        warning ("array subscript has type `char'");

      /* Apply default promotions *after* noticing character types.  */
      idx = default_conversion (idx);

      if (TREE_CODE (TREE_TYPE (idx)) != INTEGER_TYPE)
        {
          error ("array subscript is not an integer");
          return error_mark_node;
        }

      /* 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
          || (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))) != 0
              && (TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))))
                  != INTEGER_CST)))
        {
          if (mark_addressable (array) == 0)
            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_VALUES (TREE_TYPE (array))
          && ! int_fits_type_p (idx, TYPE_VALUES (TREE_TYPE (array))))
        {
          if (mark_addressable (array) == 0)
            return error_mark_node;
        }

      if (pedantic && !lvalue_p (array))
        pedwarn ("ANSI 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 ("subscripting array declared `register'");
        }

      type = TREE_TYPE (TREE_TYPE (array));
      rval = build (ARRAY_REF, type, array, idx);
      /* 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));
      return require_complete_type (fold (rval));
    }

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

    return build_indirect_ref (build_binary_op_nodefault (PLUS_EXPR, ar,
                                                          ind, PLUS_EXPR),
                               "array indexing");
  }
}
\f
/* Build a function call to function FUNCTION with parameters PARAMS.
   PARAMS is a list--a chain of TREE_LIST nodes--in which the
   TREE_VALUE of each node is a parameter-expression.  The PARAMS do
   not include any object pointer that may be required.  FUNCTION's
   data type may be a function type or a pointer-to-function.

   For C++: If FUNCTION's data type is a TREE_LIST, then the tree list
   is the list of possible methods that FUNCTION could conceivably
   be.  If the list of methods comes from a class, then it will be
   a list of lists (where each element is associated with the class
   that produced it), otherwise it will be a simple list (for
   functions overloaded in global scope).

   In the first case, TREE_VALUE (function) is the head of one of those
   lists, and TREE_PURPOSE is the name of the function.

   In the second case, TREE_PURPOSE (function) is the function's
   name directly.

   DECL is the class instance variable, usually CURRENT_CLASS_REF.

   When calling a TEMPLATE_DECL, we don't require a complete return
   type.  */

tree
build_x_function_call (function, params, decl)
     tree function, params, decl;
{
  tree type;
  tree template_id = NULL_TREE;
  int is_method;

  if (function == error_mark_node)
    return error_mark_node;

  if (processing_template_decl)
    return build_min_nt (CALL_EXPR, function, params, NULL_TREE);

  /* Save explicit template arguments if found */
  if (TREE_CODE (function) == TEMPLATE_ID_EXPR)
    {
      template_id = function;
      function = TREE_OPERAND (function, 0);
    }

  type = TREE_TYPE (function);

  if (TREE_CODE (type) == OFFSET_TYPE
      && TREE_TYPE (type) == unknown_type_node
      && TREE_CODE (function) == TREE_LIST
      && TREE_CHAIN (function) == NULL_TREE)
    {
      /* Undo (Foo:bar)()...  */
      type = TYPE_OFFSET_BASETYPE (type);
      function = TREE_VALUE (function);
      my_friendly_assert (TREE_CODE (function) == TREE_LIST, 999);
      my_friendly_assert (TREE_CHAIN (function) == NULL_TREE, 999);
      function = TREE_VALUE (function);
      if (TREE_CODE (function) == OVERLOAD)
        function = OVL_FUNCTION (function);
      my_friendly_assert (TREE_CODE (function) == FUNCTION_DECL, 999);
      function = DECL_NAME (function);
      return build_method_call (decl, function, params,
                                TYPE_BINFO (type), LOOKUP_NORMAL);
    }
    
  if ((TREE_CODE (function) == FUNCTION_DECL
       && DECL_STATIC_FUNCTION_P (function))
      || (TREE_CODE (function) == TEMPLATE_DECL
          && DECL_STATIC_FUNCTION_P (DECL_RESULT (function))))
      return build_member_call(DECL_CONTEXT (function), 
                               template_id 
                               ? template_id : DECL_NAME (function), 
                               params);

  is_method = ((TREE_CODE (function) == TREE_LIST
                && current_class_type != NULL_TREE
                && (IDENTIFIER_CLASS_VALUE (TREE_PURPOSE (function))
                    == function))
               || (TREE_CODE (function) == OVERLOAD
                   && DECL_FUNCTION_MEMBER_P (OVL_CURRENT (function)))
               || TREE_CODE (function) == IDENTIFIER_NODE
               || TREE_CODE (type) == METHOD_TYPE
               || TYPE_PTRMEMFUNC_P (type));

  /* A friend template.  Make it look like a toplevel declaration.  */
  if (! is_method && TREE_CODE (function) == TEMPLATE_DECL)
    function = scratch_ovl_cons (function, NULL_TREE);

  /* Handle methods, friends, and overloaded functions, respectively.  */
  if (is_method)
    {
      tree basetype = NULL_TREE;

      if (TREE_CODE (function) == OVERLOAD)
        function = OVL_CURRENT (function);

      if (TREE_CODE (function) == FUNCTION_DECL
          || DECL_FUNCTION_TEMPLATE_P (function))
        {
          basetype = DECL_CLASS_CONTEXT (function);

          if (DECL_NAME (function))
            function = DECL_NAME (function);
          else
            function = TYPE_IDENTIFIER (DECL_CLASS_CONTEXT (function));
        }
      else if (TREE_CODE (function) == TREE_LIST)
        {
          my_friendly_assert (TREE_CODE (TREE_VALUE (function))
                              == FUNCTION_DECL, 312);
          basetype = DECL_CLASS_CONTEXT (TREE_VALUE (function));
          function = TREE_PURPOSE (function);
        }
      else if (TREE_CODE (function) != IDENTIFIER_NODE)
        {
          if (TREE_CODE (function) == OFFSET_REF)
            {
              if (TREE_OPERAND (function, 0))
                decl = TREE_OPERAND (function, 0);
            }
          /* Call via a pointer to member function.  */
          if (decl == NULL_TREE)
            {
              error ("pointer to member function called, but not in class scope");
              return error_mark_node;
            }
          /* What other type of POINTER_TYPE could this be? */
          if (TREE_CODE (TREE_TYPE (function)) != POINTER_TYPE
              && ! TYPE_PTRMEMFUNC_P (TREE_TYPE (function))
              && TREE_CODE (function) != OFFSET_REF)
            function = build (OFFSET_REF, TREE_TYPE (type), NULL_TREE,
                              function);
          goto do_x_function;
        }

      /* this is an abbreviated method call.
         must go through here in case it is a virtual function.
         @@ Perhaps this could be optimized.  */

      if (basetype && (! current_class_type
                       || ! DERIVED_FROM_P (basetype, current_class_type)))
        return build_member_call (basetype, function, params);

      if (decl == NULL_TREE)
        {
          if (current_class_type == NULL_TREE)
            {
              cp_error ("object missing in call to method `%D'", function);
              return error_mark_node;
            }
          /* Yow: call from a static member function.  */
          decl = build_dummy_object (current_class_type);
        }

      /* Put back explicit template arguments, if any.  */
      if (template_id)
        function = template_id;
      return build_method_call (decl, function, params,
                                NULL_TREE, LOOKUP_NORMAL);
    }
  else if (TREE_CODE (function) == COMPONENT_REF
           && type == unknown_type_node)
    {
      /* Undo what we did in build_component_ref.  */
      decl = TREE_OPERAND (function, 0);
      function = TREE_OPERAND (function, 1);
      function = DECL_NAME (OVL_CURRENT (function));

      if (template_id)
        {
          TREE_OPERAND (template_id, 0) = function;
          function = template_id;
        }

      return build_method_call (decl, function, params,
                                NULL_TREE, LOOKUP_NORMAL);
    }
  else if (really_overloaded_fn (function))
    {
      if (OVL_FUNCTION (function) == NULL_TREE)
        {
          cp_error ("function `%D' declared overloaded, but no definitions appear with which to resolve it?!?",
                    TREE_PURPOSE (function));
          return error_mark_node;
        }
      else
        {
          /* Put back explicit template arguments, if any.  */
          if (template_id)
            function = template_id;
          return build_new_function_call (function, params);
        }
    }
  else
    /* Remove a potential OVERLOAD around it */
    function = OVL_CURRENT (function);

 do_x_function:
  if (TREE_CODE (function) == OFFSET_REF)
    {
      /* If the component is a data element (or a virtual function), we play
         games here to make things work.  */
      tree decl_addr;

      if (TREE_OPERAND (function, 0))
        decl = TREE_OPERAND (function, 0);
      else
        decl = current_class_ref;

      decl_addr = build_unary_op (ADDR_EXPR, decl, 0);

      /* Sigh.  OFFSET_REFs are being used for too many things.
         They're being used both for -> and ->*, and we want to resolve
         the -> cases here, but leave the ->*.  We could use
         resolve_offset_ref for those, too, but it would call
         get_member_function_from_ptrfunc and decl_addr wouldn't get
         updated properly.  Nasty.  */
      if (TREE_CODE (TREE_OPERAND (function, 1)) == FIELD_DECL)
        function = resolve_offset_ref (function);
      else
        function = TREE_OPERAND (function, 1);

      function = get_member_function_from_ptrfunc (&decl_addr, function);
      params = tree_cons (NULL_TREE, decl_addr, params);
      return build_function_call (function, params);
    }

  type = TREE_TYPE (function);
  if (type != error_mark_node)
    {
      if (TREE_CODE (type) == REFERENCE_TYPE)
        type = TREE_TYPE (type);

      if (IS_AGGR_TYPE (type))
        return build_opfncall (CALL_EXPR, LOOKUP_NORMAL, function, params, NULL_TREE);
    }

  if (is_method)
    {
      tree fntype = TREE_TYPE (function);
      tree ctypeptr = NULL_TREE;

      /* Explicitly named method?  */
      if (TREE_CODE (function) == FUNCTION_DECL)
        ctypeptr = build_pointer_type (DECL_CLASS_CONTEXT (function));
      /* Expression with ptr-to-method type?  It could either be a plain
         usage, or it might be a case where the ptr-to-method is being
         passed in as an argument.  */
      else if (TYPE_PTRMEMFUNC_P (fntype))
        {
          tree rec = TYPE_METHOD_BASETYPE (TREE_TYPE
                                           (TYPE_PTRMEMFUNC_FN_TYPE (fntype)));
          ctypeptr = build_pointer_type (rec);
        }
      /* Unexpected node type?  */
      else
        my_friendly_abort (116);
      if (decl == NULL_TREE)
        {
          if (current_function_decl
              && DECL_STATIC_FUNCTION_P (current_function_decl))
            error ("invalid call to member function needing `this' in static member function scope");
          else
            error ("pointer to member function called, but not in class scope");
          return error_mark_node;
        }
      if (TREE_CODE (TREE_TYPE (decl)) != POINTER_TYPE
          && ! TYPE_PTRMEMFUNC_P (TREE_TYPE (decl)))
        {
          decl = build_unary_op (ADDR_EXPR, decl, 0);
          decl = convert_pointer_to (TREE_TYPE (ctypeptr), decl);
        }
      else
        decl = build_c_cast (ctypeptr, decl);
      params = tree_cons (NULL_TREE, decl, params);
    }

  return build_function_call (function, params);
}

/* Resolve a pointer to member function.  INSTANCE is the object
   instance to use, if the member points to a virtual member.  */

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

  if (TYPE_PTRMEMFUNC_P (TREE_TYPE (function)))
    {
      tree fntype, idx, e1, delta, delta2, e2, e3, aref, vtbl;
      tree instance, basetype;

      tree instance_ptr = *instance_ptrptr;

      if (instance_ptr == error_mark_node
          && 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 (TYPE_PTRMEMFUNC_FN_TYPE (TREE_TYPE (function)), e1);
          return e1;
        }

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

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

      fntype = TYPE_PTRMEMFUNC_FN_TYPE (TREE_TYPE (function));
      basetype = TYPE_METHOD_BASETYPE (TREE_TYPE (fntype));

      delta = cp_convert (ptrdiff_type_node,
                          build_component_ref (function, delta_identifier,
                                               NULL_TREE, 0));
      e3 = PFN_FROM_PTRMEMFUNC (function);

      /* 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. */

      /* Promoting idx before saving it improves performance on RISC
         targets.  Without promoting, the first compare used
         load-with-sign-extend, while the second used normal load then
         shift to sign-extend.  An optimizer flaw, perhaps, but it's
         easier to make this change.  */
      idx = save_expr (default_conversion
                       (build_component_ref (function,
                                             index_identifier,
                                             NULL_TREE, 0)));
      e1 = build_binary_op (GE_EXPR, idx, integer_zero_node);

      /* Convert down to the right base, before using the instance.  */
      instance = convert_pointer_to_real (basetype, instance_ptr);
      if (instance == error_mark_node && instance_ptr != error_mark_node)
        return instance;

      vtbl = convert_pointer_to (ptr_type_node, instance);
      delta2 = DELTA2_FROM_PTRMEMFUNC (function);
      vtbl = build
        (PLUS_EXPR,
         build_pointer_type (build_pointer_type (vtable_entry_type)),
         vtbl, cp_convert (ptrdiff_type_node, delta2));
      vtbl = build_indirect_ref (vtbl, NULL_PTR);
      aref = build_array_ref (vtbl, build_binary_op (MINUS_EXPR,
                                                     idx,
                                                     integer_one_node));
      if (! flag_vtable_thunks)
        {
          aref = save_expr (aref);
          
          delta = build_binary_op
            (PLUS_EXPR,
             build_conditional_expr (e1,
                                     build_component_ref (aref,
                                                          delta_identifier,
                                                          NULL_TREE, 0),
                                     integer_zero_node),
             delta);
        }

      if (flag_vtable_thunks)
        e2 = aref;
      else
        e2 = build_component_ref (aref, pfn_identifier, NULL_TREE, 0);
      TREE_TYPE (e2) = TREE_TYPE (e3);
      e1 = build_conditional_expr (e1, e2, e3);
      
      /* Make sure this doesn't get evaluated first inside one of the
         branches of the COND_EXPR.  */
      if (TREE_CODE (instance_ptr) == SAVE_EXPR)
        e1 = build (COMPOUND_EXPR, TREE_TYPE (e1),
                    instance_ptr, e1);

      *instance_ptrptr = build (PLUS_EXPR, TREE_TYPE (instance_ptr),
                                instance_ptr, delta);

      if (instance_ptr == error_mark_node
          && TREE_CODE (e1) != ADDR_EXPR
          && TREE_CODE (TREE_OPERAND (e1, 0)) != FUNCTION_DECL)
        cp_error ("object missing in `%E'", function);

      function = e1;
    }
  return function;
}

tree
build_function_call_real (function, params, require_complete, flags)
     tree function, params;
     int require_complete, flags;
{
  register tree fntype, fndecl;
  register tree value_type;
  register tree coerced_params;
  tree name = NULL_TREE, assembler_name = NULL_TREE;
  int is_method;

  /* 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)
    {
      name = DECL_NAME (function);
      assembler_name = DECL_ASSEMBLER_NAME (function);

      GNU_xref_call (current_function_decl,
                     IDENTIFIER_POINTER (name ? name
                                         : TYPE_IDENTIFIER (DECL_CLASS_CONTEXT
                                                            (function))));
      mark_used (function);
      fndecl = function;

      /* Convert anything with function type to a pointer-to-function.  */
      if (pedantic && DECL_MAIN_P (function))
        pedwarn ("ANSI C++ forbids calling `main' from within program");

      /* Differs from default_conversion by not setting TREE_ADDRESSABLE
         (because calling an inline function does not mean the function
         needs to be separately compiled).  */

      if (DECL_INLINE (function))
        function = inline_conversion (function);
      else
        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))
    {
      cp_error ("must use .* or ->* to call pointer-to-member function in `%E (...)'",
                function);
      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))
    {
      cp_error ("`%E' cannot be used as a function", function);
      return error_mark_node;
    }

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

  /* Convert the parameters to the types declared in the
     function prototype, or apply default promotions.  */

  if (flags & LOOKUP_COMPLAIN)
    coerced_params = convert_arguments (TYPE_ARG_TYPES (fntype),
                                        params, fndecl, LOOKUP_NORMAL);
  else
    coerced_params = convert_arguments (TYPE_ARG_TYPES (fntype),
                                        params, fndecl, 0);

  if (coerced_params == error_mark_node)
    {
      if (flags & LOOKUP_SPECULATIVELY)
        return NULL_TREE;
      else
        return error_mark_node;
    }

  /* Check for errors in format strings.  */

  if (warn_format && (name || assembler_name))
    check_function_format (name, assembler_name, coerced_params);

  /* Recognize certain built-in functions so we can make tree-codes
     other than CALL_EXPR.  We do this when it enables fold-const.c
     to do something useful.  */

  if (TREE_CODE (function) == ADDR_EXPR
      && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL
      && DECL_BUILT_IN (TREE_OPERAND (function, 0))
      && DECL_BUILT_IN_CLASS (TREE_OPERAND (function, 0)) == BUILT_IN_NORMAL)
    switch (DECL_FUNCTION_CODE (TREE_OPERAND (function, 0)))
      {
      case BUILT_IN_ABS:
      case BUILT_IN_LABS:
      case BUILT_IN_FABS:
        if (coerced_params == 0)
          return integer_zero_node;
        return build_unary_op (ABS_EXPR, TREE_VALUE (coerced_params), 0);

      default:
        break;
      }

  /* C++ */
  value_type = TREE_TYPE (fntype) ? TREE_TYPE (fntype) : void_type_node;
  {
    register tree result
      = build_call (function, value_type, coerced_params);

    if (require_complete)
      {
        if (TREE_CODE (value_type) == VOID_TYPE)
          return result;
        result = require_complete_type (result);
      }
    if (IS_AGGR_TYPE (value_type))
      result = build_cplus_new (value_type, result);
    return convert_from_reference (result);
  }
}

tree
build_function_call (function, params)
     tree function, params;
{
  return build_function_call_real (function, params, 1, LOOKUP_NORMAL);
}
\f
/* Convert the actual parameter expressions in the list VALUES
   to the types in the list TYPELIST.
   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.
   
   Return a list of expressions for the parameters as converted.

   Both VALUES and the returned value are chains of TREE_LIST nodes
   with the elements of the list in the TREE_VALUE slots of those nodes.

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

tree
convert_arguments (typelist, values, fndecl, flags)
     tree typelist, values, fndecl;
     int flags;
{
  register tree typetail, valtail;
  register tree result = NULL_TREE;
  const char *called_thing = 0;
  int i = 0;

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

  if (fndecl)
    {
      if (TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE)
        {
          if (DECL_NAME (fndecl) == NULL_TREE
              || IDENTIFIER_HAS_TYPE_VALUE (DECL_NAME (fndecl)))
            called_thing = "constructor";
          else
            called_thing = "member function";
        }
      else
        called_thing = "function";
    }

  for (valtail = values, typetail = typelist;
       valtail;
       valtail = TREE_CHAIN (valtail), i++)
    {
      register tree type = typetail ? TREE_VALUE (typetail) : 0;
      register tree val = TREE_VALUE (valtail);

      if (val == error_mark_node)
        return error_mark_node;

      if (type == void_type_node)
        {
          if (fndecl)
            {
              cp_error_at ("too many arguments to %s `%+#D'", called_thing,
                           fndecl);
              error ("at this point in file");
            }
          else
            error ("too many arguments to function");
          /* In case anybody wants to know if this argument
             list is valid.  */
          if (result)
            TREE_TYPE (tree_last (result)) = error_mark_node;
          break;
        }

      if (TREE_CODE (val) == OFFSET_REF)
        val = resolve_offset_ref (val);

      /* 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 = default_conversion (val);
        }

      if (val == error_mark_node)
        return error_mark_node;

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

          if (TYPE_SIZE (complete_type (type)) == 0)
            {
              error ("parameter type of called function is incomplete");
              parmval = val;
            }
          else
            {
              parmval = convert_for_initialization
                (NULL_TREE, type, val, flags,
                 "argument passing", fndecl, i);
              if (PROMOTE_PROTOTYPES
                  && (TREE_CODE (type) == INTEGER_TYPE
                      || TREE_CODE (type) == ENUMERAL_TYPE)
                  && (TYPE_PRECISION (type)
                      < TYPE_PRECISION (integer_type_node)))
                parmval = default_conversion (parmval);
            }

          if (parmval == error_mark_node)
            return error_mark_node;

          result = tree_cons (NULL_TREE, parmval, result);
        }
      else
        {
          if (TREE_CODE (TREE_TYPE (val)) == REFERENCE_TYPE)
            val = convert_from_reference (val);

          result = tree_cons (NULL_TREE,
                                   convert_arg_to_ellipsis (val),
                                   result);
        }

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

  if (typetail != 0 && typetail != void_list_node)
    {
      /* See if there are default arguments that can be used */
      if (TREE_PURPOSE (typetail))
        {
          for (; typetail != void_list_node; ++i)
            {
              tree parmval 
                = convert_default_arg (TREE_VALUE (typetail), 
                                       TREE_PURPOSE (typetail), 
                                       fndecl);

              if (parmval == error_mark_node)
                return error_mark_node;

              result = tree_cons (0, parmval, result);
              typetail = TREE_CHAIN (typetail);
              /* ends with `...'.  */
              if (typetail == NULL_TREE)
                break;
            }
        }
      else
        {
          if (fndecl)
            {
              cp_error_at ("too few arguments to %s `%+#D'",
                           called_thing, fndecl);
              error ("at this point in file");
            }
          else
            error ("too few arguments to function");
          return error_mark_list;
        }
    }

  return nreverse (result);
}
\f
/* Build a binary-operation expression, after performing default
   conversions on the operands.  CODE is the kind of expression to build.  */

tree
build_x_binary_op (code, arg1, arg2)
     enum tree_code code;
     tree arg1, arg2;
{
  if (processing_template_decl)
    return build_min_nt (code, arg1, arg2);

  return build_new_op (code, LOOKUP_NORMAL, arg1, arg2, NULL_TREE);
}

tree
build_binary_op (code, arg1, arg2)
     enum tree_code code;
     tree arg1, arg2;
{
  return build_binary_op_nodefault (code, arg1, arg2, code);
}

/* Build a binary-operation expression without default conversions.
   CODE is the kind of expression to build.
   This function differs from `build' in several ways:
   the data type of the result is computed and recorded in it,
   warnings are generated if arg data types are invalid,
   special handling for addition and subtraction of pointers is known,
   and some optimization is done (operations on narrow ints
   are done in the narrower type when that gives the same result).
   Constant folding is also done before the result is returned.

   ERROR_CODE is the code that determines what to say in error messages.
   It is usually, but not always, the same as CODE.

   Note that the operands will never have enumeral types
   because either they have just had the default conversions performed
   or they have both just been converted to some other type in which
   the arithmetic is to be done.

   C++: must do special pointer arithmetic when implementing
   multiple inheritance, and deal with pointer to member functions.  */

tree
build_binary_op_nodefault (code, orig_op0, orig_op1, error_code)
     enum tree_code code;
     tree orig_op0, orig_op1;
     enum tree_code error_code;
{
  tree op0, op1;
  register enum tree_code code0, code1;
  tree type0, type1;

  /* Expression code to give to the expression when it is built.
     Normally this is CODE, which is what the caller asked for,
     but in some special cases we change it.  */
  register enum tree_code resultcode = code;

  /* Data type in which the computation is to be performed.
     In the simplest cases this is the common type of the arguments.  */
  register tree result_type = NULL;

  /* Nonzero means operands have already been type-converted
     in whatever way is necessary.
     Zero means they need to be converted to RESULT_TYPE.  */
  int converted = 0;

  /* Nonzero means create the expression with this type, rather than
     RESULT_TYPE.  */
  tree build_type = 0;

  /* Nonzero means after finally constructing the expression
     convert it to this type.  */
  tree final_type = 0;

  /* Nonzero if this is an operation like MIN or MAX which can
     safely be computed in short if both args are promoted shorts.
     Also implies COMMON.
     -1 indicates a bitwise operation; this makes a difference
     in the exact conditions for when it is safe to do the operation
     in a narrower mode.  */
  int shorten = 0;

  /* Nonzero if this is a comparison operation;
     if both args are promoted shorts, compare the original shorts.
     Also implies COMMON.  */
  int short_compare = 0;

  /* Nonzero if this is a right-shift operation, which can be computed on the
     original short and then promoted if the operand is a promoted short.  */
  int short_shift = 0;

  /* Nonzero means set RESULT_TYPE to the common type of the args.  */
  int common = 0;

  /* Apply default conversions.  */
  if (code == TRUTH_AND_EXPR || code == TRUTH_ANDIF_EXPR
      || code == TRUTH_OR_EXPR || code == TRUTH_ORIF_EXPR
      || code == TRUTH_XOR_EXPR)
    {
      op0 = decay_conversion (orig_op0);
      op1 = decay_conversion (orig_op1);
    }
  else
    {
      op0 = default_conversion (orig_op0);
      op1 = default_conversion (orig_op1);
    }

  /* Strip NON_LVALUE_EXPRs, etc., since we aren't using as an lvalue.  */
  STRIP_TYPE_NOPS (op0);
  STRIP_TYPE_NOPS (op1);

  /* DTRT if one side is an overloaded function, but complain about it.  */
  if (type_unknown_p (op0))
    {
      tree t = instantiate_type (TREE_TYPE (op1), op0, 0);
      if (t != error_mark_node)
        {
          cp_pedwarn ("assuming cast to `%T' from overloaded function",
                      TREE_TYPE (t));
          op0 = t;
        }
    }
  if (type_unknown_p (op1))
    {
      tree t = instantiate_type (TREE_TYPE (op0), op1, 0);
      if (t != error_mark_node)
        {
          cp_pedwarn ("assuming cast to `%T' from overloaded function",
                      TREE_TYPE (t));
          op1 = t;
        }
    }

  type0 = TREE_TYPE (op0);
  type1 = TREE_TYPE (op1);

  /* The expression codes of the data types of the arguments tell us
     whether the arguments are integers, floating, pointers, etc.  */
  code0 = TREE_CODE (type0);
  code1 = TREE_CODE (type1);

  /* If an error was already reported for one of the arguments,
     avoid reporting another error.  */

  if (code0 == ERROR_MARK || code1 == ERROR_MARK)
    return error_mark_node;

  switch (code)
    {
    case PLUS_EXPR:
      /* Handle the pointer + int case.  */
      if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
        return pointer_int_sum (PLUS_EXPR, op0, op1);
      else if (code1 == POINTER_TYPE && code0 == INTEGER_TYPE)
        return pointer_int_sum (PLUS_EXPR, op1, op0);
      else
        common = 1;
      break;

    case MINUS_EXPR:
      /* Subtraction of two similar pointers.
         We must subtract them as integers, then divide by object size.  */
      if (code0 == POINTER_TYPE && code1 == POINTER_TYPE
          && comp_target_types (type0, type1, 1))
        return pointer_diff (op0, op1, common_type (type0, type1));
      /* Handle pointer minus int.  Just like pointer plus int.  */
      else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
        return pointer_int_sum (MINUS_EXPR, op0, op1);
      else
        common = 1;
      break;

    case MULT_EXPR:
      common = 1;
      break;

    case TRUNC_DIV_EXPR:
    case CEIL_DIV_EXPR:
    case FLOOR_DIV_EXPR:
    case ROUND_DIV_EXPR:
    case EXACT_DIV_EXPR:
      if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
           || code0 == COMPLEX_TYPE)
          && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
              || code1 == COMPLEX_TYPE))
        {
          if (TREE_CODE (op1) == INTEGER_CST && integer_zerop (op1))
            cp_warning ("division by zero in `%E / 0'", op0);
          else if (TREE_CODE (op1) == REAL_CST && real_zerop (op1))
            cp_warning ("division by zero in `%E / 0.'", op0);
              
          if (!(code0 == INTEGER_TYPE && code1 == INTEGER_TYPE))
            resultcode = RDIV_EXPR;
          else
            /* When dividing two signed integers, we have to promote to int.
               unless we divide by a constant != -1.  Note that default
               conversion will have been performed on the operands at this
               point, so we have to dig out the original type to find out if
               it was unsigned.  */
            shorten = ((TREE_CODE (op0) == NOP_EXPR
                        && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
                       || (TREE_CODE (op1) == INTEGER_CST
                           && (TREE_INT_CST_LOW (op1) != -1
                               || TREE_INT_CST_HIGH (op1) != -1)));
          common = 1;
        }
      break;

    case BIT_AND_EXPR:
    case BIT_ANDTC_EXPR:
    case BIT_IOR_EXPR:
    case BIT_XOR_EXPR:
      if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
        shorten = -1;
      /* If one operand is a constant, and the other is a short type
         that has been converted to an int,
         really do the work in the short type and then convert the
         result to int.  If we are lucky, the constant will be 0 or 1
         in the short type, making the entire operation go away.  */
      if (TREE_CODE (op0) == INTEGER_CST
          && TREE_CODE (op1) == NOP_EXPR
          && (TYPE_PRECISION (type1)
              > TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (op1, 0))))
          && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op1, 0))))
        {
          final_type = result_type;
          op1 = TREE_OPERAND (op1, 0);
          result_type = TREE_TYPE (op1);
        }
      if (TREE_CODE (op1) == INTEGER_CST
          && TREE_CODE (op0) == NOP_EXPR
          && (TYPE_PRECISION (type0)
              > TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (op0, 0))))
          && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
        {
          final_type = result_type;
          op0 = TREE_OPERAND (op0, 0);
          result_type = TREE_TYPE (op0);
        }
      break;

    case TRUNC_MOD_EXPR:
    case FLOOR_MOD_EXPR:
      if (code1 == INTEGER_TYPE && integer_zerop (op1))
        cp_warning ("division by zero in `%E %% 0'", op0);
      else if (code1 == REAL_TYPE && real_zerop (op1))
        cp_warning ("division by zero in `%E %% 0.'", op0);
      
      if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
        {
          /* Although it would be tempting to shorten always here, that loses
             on some targets, since the modulo instruction is undefined if the
             quotient can't be represented in the computation mode.  We shorten
             only if unsigned or if dividing by something we know != -1.  */
          shorten = ((TREE_CODE (op0) == NOP_EXPR
                      && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (op0, 0))))
                     || (TREE_CODE (op1) == INTEGER_CST
                         && (TREE_INT_CST_LOW (op1) != -1
                             || TREE_INT_CST_HIGH (op1) != -1)));
          common = 1;
        }
      break;

    case TRUTH_ANDIF_EXPR:
    case TRUTH_ORIF_EXPR:
    case TRUTH_AND_EXPR:
    case TRUTH_OR_EXPR:
      result_type = boolean_type_node;
      break;

      /* Shift operations: result has same type as first operand;
         always convert second operand to int.
         Also set SHORT_SHIFT if shifting rightward.  */

    case RSHIFT_EXPR:
      if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
        {
          result_type = type0;
          if (TREE_CODE (op1) == INTEGER_CST)
            {
              if (tree_int_cst_lt (op1, integer_zero_node))
                warning ("right shift count is negative");
              else
                {
                  if (TREE_INT_CST_LOW (op1) | TREE_INT_CST_HIGH (op1))
                    short_shift = 1;
                  if (TREE_INT_CST_HIGH (op1) != 0
                      || ((unsigned HOST_WIDE_INT) TREE_INT_CST_LOW (op1)
                          >= TYPE_PRECISION (type0)))
                    warning ("right shift count >= width of type");
                }
            }
          /* Convert the shift-count to an integer, regardless of
             size of value being shifted.  */
          if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
            op1 = cp_convert (integer_type_node, op1);
          /* Avoid converting op1 to result_type later.  */
          converted = 1;
        }
      break;

    case LSHIFT_EXPR:
      if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
        {
          result_type = type0;
          if (TREE_CODE (op1) == INTEGER_CST)
            {
              if (tree_int_cst_lt (op1, integer_zero_node))
                warning ("left shift count is negative");
              else if (TREE_INT_CST_HIGH (op1) != 0
                       || ((unsigned HOST_WIDE_INT) TREE_INT_CST_LOW (op1)
                           >= TYPE_PRECISION (type0)))
                warning ("left shift count >= width of type");
            }
          /* Convert the shift-count to an integer, regardless of
             size of value being shifted.  */
          if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
            op1 = cp_convert (integer_type_node, op1);
          /* Avoid converting op1 to result_type later.  */
          converted = 1;
        }
      break;

    case RROTATE_EXPR:
    case LROTATE_EXPR:
      if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
        {
          result_type = type0;
          if (TREE_CODE (op1) == INTEGER_CST)
            {
              if (tree_int_cst_lt (op1, integer_zero_node))
                warning ("%s rotate count is negative",
                         (code == LROTATE_EXPR) ? "left" : "right");
              else if (TREE_INT_CST_HIGH (op1) != 0
                       || ((unsigned HOST_WIDE_INT) TREE_INT_CST_LOW (op1)
                           >= TYPE_PRECISION (type0)))
                warning ("%s rotate count >= width of type",
                         (code == LROTATE_EXPR) ? "left" : "right");
            }
          /* Convert the shift-count to an integer, regardless of
             size of value being shifted.  */
          if (TYPE_MAIN_VARIANT (TREE_TYPE (op1)) != integer_type_node)
            op1 = cp_convert (integer_type_node, op1);
        }
      break;

    case EQ_EXPR:
    case NE_EXPR:
      if (warn_float_equal && (code0 == REAL_TYPE || code1 == REAL_TYPE))
        warning ("comparing floating point with == or != is unsafe");

      build_type = boolean_type_node; 
      if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE
           || code0 == COMPLEX_TYPE)
          && (code1 == INTEGER_TYPE || code1 == REAL_TYPE
              || code1 == COMPLEX_TYPE))
        short_compare = 1;
      else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
        {
          register tree tt0 = TYPE_MAIN_VARIANT (TREE_TYPE (type0));
          register tree tt1 = TYPE_MAIN_VARIANT (TREE_TYPE (type1));

          if (comp_target_types (type0, type1, 1))
            result_type = common_type (type0, type1);
          else if (tt0 == void_type_node)
            {
              if (pedantic && TREE_CODE (tt1) == FUNCTION_TYPE
                  && tree_int_cst_lt (TYPE_SIZE (type0), TYPE_SIZE (type1)))
                pedwarn ("ANSI C++ forbids comparison of `void *' with function pointer");
              else if (TREE_CODE (tt1) == OFFSET_TYPE)
                pedwarn ("ANSI C++ forbids conversion of a pointer to member to `void *'");
            }
          else if (tt1 == void_type_node)
            {
              if (pedantic && TREE_CODE (tt0) == FUNCTION_TYPE
                  && tree_int_cst_lt (TYPE_SIZE (type1), TYPE_SIZE (type0)))
                pedwarn ("ANSI C++ forbids comparison of `void *' with function pointer");
            }
          else
            cp_pedwarn ("comparison of distinct pointer types `%T' and `%T' lacks a cast",
                        type0, type1);

          if (result_type == NULL_TREE)
            result_type = ptr_type_node;
        }
      else if (code0 == POINTER_TYPE && null_ptr_cst_p (op1))
        result_type = type0;
      else if (code1 == POINTER_TYPE && null_ptr_cst_p (op0))
        result_type = type1;
      else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
        {
          result_type = type0;
          error ("ANSI C++ forbids comparison between pointer and integer");
        }
      else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
        {
          result_type = type1;
          error ("ANSI C++ forbids comparison between pointer and integer");
        }
      else if (TYPE_PTRMEMFUNC_P (type0) && null_ptr_cst_p (op1))
        {
          op0 = build_component_ref (op0, index_identifier, NULL_TREE, 0);
          op1 = integer_zero_node;
          result_type = TREE_TYPE (op0);
        }
      else if (TYPE_PTRMEMFUNC_P (type1) && null_ptr_cst_p (op0))
        {
          op0 = build_component_ref (op1, index_identifier, NULL_TREE, 0);
          op1 = integer_zero_node;
          result_type = TREE_TYPE (op0);
        }
      else if (TYPE_PTRMEMFUNC_P (type0) && TYPE_PTRMEMFUNC_P (type1)
               && same_type_p (type0, type1))
        {
          /* The code we generate for the test is:

          (op0.index == op1.index
           && ((op1.index != -1 && op0.delta2 == op1.delta2)
               || op0.pfn == op1.pfn)) */

          tree index0 = build_component_ref (op0, index_identifier,
                                             NULL_TREE, 0);
          tree index1 = save_expr (build_component_ref (op1, index_identifier,
                                                        NULL_TREE, 0));
          tree pfn0 = PFN_FROM_PTRMEMFUNC (op0);
          tree pfn1 = PFN_FROM_PTRMEMFUNC (op1);
          tree delta20 = DELTA2_FROM_PTRMEMFUNC (op0);
          tree delta21 = DELTA2_FROM_PTRMEMFUNC (op1);
          tree e1, e2, e3;
          tree integer_neg_one_node
            = build_binary_op (MINUS_EXPR, integer_zero_node,
                               integer_one_node);
          e1 = build_binary_op (EQ_EXPR, index0, index1);
          e2 = build_binary_op (NE_EXPR, index1, integer_neg_one_node);
          e2 = build_binary_op (TRUTH_ANDIF_EXPR, e2,
                                build_binary_op (EQ_EXPR, delta20, delta21));
          /* We can't use build_binary_op for this cmp because it would get
             confused by the ptr to method types and think we want pmfs.  */
          e3 = build (EQ_EXPR, boolean_type_node, pfn0, pfn1);
          e2 = build_binary_op (TRUTH_ORIF_EXPR, e2, e3);
          e2 = build_binary_op (TRUTH_ANDIF_EXPR, e1, e2);
          if (code == EQ_EXPR)
            return e2;
          return build_binary_op (EQ_EXPR, e2, integer_zero_node);
        }
      else if (TYPE_PTRMEMFUNC_P (type0)
               && same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type0), type1))
        {
          tree index0 = build_component_ref (op0, index_identifier,
                                             NULL_TREE, 0);
          tree index1;
          tree pfn0 = PFN_FROM_PTRMEMFUNC (op0);
          tree delta20 = DELTA2_FROM_PTRMEMFUNC (op0);
          tree delta21 = integer_zero_node;
          tree e1, e2, e3;
          tree integer_neg_one_node
            = build_binary_op (MINUS_EXPR, integer_zero_node, integer_one_node);
          if (TREE_CODE (TREE_OPERAND (op1, 0)) == FUNCTION_DECL
              && DECL_VINDEX (TREE_OPERAND (op1, 0)))
            {
              /* Map everything down one to make room for
                 the null pointer to member.  */
              index1 = size_binop (PLUS_EXPR,
                                   DECL_VINDEX (TREE_OPERAND (op1, 0)),
                                   integer_one_node);
              op1 = integer_zero_node;
              delta21 = TYPE_VFIELD (TYPE_METHOD_BASETYPE
                                     (TREE_TYPE (type1)));
              delta21 = DECL_FIELD_BITPOS (delta21);
              delta21 = size_binop (FLOOR_DIV_EXPR, delta21,
                                    size_int (BITS_PER_UNIT));
              delta21 = convert (sizetype, delta21);
            }
          else
            index1 = integer_neg_one_node;
          {
            tree nop1 = build1 (NOP_EXPR, TYPE_PTRMEMFUNC_FN_TYPE (type0),
                                op1);
            TREE_CONSTANT (nop1) = TREE_CONSTANT (op1);
            op1 = nop1;
          }
          e1 = build_binary_op (EQ_EXPR, index0, index1);
          e2 = build_binary_op (NE_EXPR, index1, integer_neg_one_node);
          e2 = build_binary_op (TRUTH_ANDIF_EXPR, e2,
                                build_binary_op (EQ_EXPR, delta20, delta21));
          /* We can't use build_binary_op for this cmp because it would get
             confused by the ptr to method types and think we want pmfs.  */
          e3 = build (EQ_EXPR, boolean_type_node, pfn0, op1);
          e2 = build_binary_op (TRUTH_ORIF_EXPR, e2, e3);
          e2 = build_binary_op (TRUTH_ANDIF_EXPR, e1, e2);
          if (code == EQ_EXPR)
            return e2;
          return build_binary_op (EQ_EXPR, e2, integer_zero_node);
        }
      else if (TYPE_PTRMEMFUNC_P (type1)
               && same_type_p (TYPE_PTRMEMFUNC_FN_TYPE (type1), type0))
        return build_binary_op (code, op1, op0);
      break;

    case MAX_EXPR:
    case MIN_EXPR:
      if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
        shorten = 1;
      else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
        {
          if (comp_target_types (type0, type1, 1))
            result_type = common_type (type0, type1);
          else
            {
              cp_pedwarn ("comparison of distinct pointer types `%T' and `%T' lacks a cast",
                          type0, type1);
              result_type = ptr_type_node;
            }
        }
      break;

    case LE_EXPR:
    case GE_EXPR:
    case LT_EXPR:
    case GT_EXPR:
      build_type = boolean_type_node;
      if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE)
           && (code1 == INTEGER_TYPE || code1 == REAL_TYPE))
        short_compare = 1;
      else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
        {
          if (comp_target_types (type0, type1, 1))
            result_type = common_type (type0, type1);
          else
            {
              cp_pedwarn ("comparison of distinct pointer types `%T' and `%T' lacks a cast",
                          type0, type1);
              result_type = ptr_type_node;
            }
        }
      else if (code0 == POINTER_TYPE && TREE_CODE (op1) == INTEGER_CST
               && integer_zerop (op1))
        result_type = type0;
      else if (code1 == POINTER_TYPE && TREE_CODE (op0) == INTEGER_CST
               && integer_zerop (op0))
        result_type = type1;
      else if (code0 == POINTER_TYPE && code1 == INTEGER_TYPE)
        {
          result_type = type0;
          pedwarn ("ANSI C++ forbids comparison between pointer and integer");
        }
      else if (code0 == INTEGER_TYPE && code1 == POINTER_TYPE)
        {
          result_type = type1;
          pedwarn ("ANSI C++ forbids comparison between pointer and integer");
        }
      break;

    default:
      break;
    }

  if ((code0 == INTEGER_TYPE || code0 == REAL_TYPE || code0 == COMPLEX_TYPE)
      &&
      (code1 == INTEGER_TYPE || code1 == REAL_TYPE || code1 == COMPLEX_TYPE))
    {
      int none_complex = (code0 != COMPLEX_TYPE && code1 != COMPLEX_TYPE);

      if (shorten || common || short_compare)
        result_type = common_type (type0, type1);

      /* For certain operations (which identify themselves by shorten != 0)
         if both args were extended from the same smaller type,
         do the arithmetic in that type and then extend.

         shorten !=0 and !=1 indicates a bitwise operation.
         For them, this optimization is safe only if
         both args are zero-extended or both are sign-extended.
         Otherwise, we might change the result.
         Eg, (short)-1 | (unsigned short)-1 is (int)-1
         but calculated in (unsigned short) it would be (unsigned short)-1.  */

      if (shorten && none_complex)
        {
          int unsigned0, unsigned1;
          tree arg0 = get_narrower (op0, &unsigned0);
          tree arg1 = get_narrower (op1, &unsigned1);
          /* UNS is 1 if the operation to be done is an unsigned one.  */
          int uns = TREE_UNSIGNED (result_type);
          tree type;

          final_type = result_type;

          /* Handle the case that OP0 does not *contain* a conversion
             but it *requires* conversion to FINAL_TYPE.  */

          if (op0 == arg0 && TREE_TYPE (op0) != final_type)
            unsigned0 = TREE_UNSIGNED (TREE_TYPE (op0));
          if (op1 == arg1 && TREE_TYPE (op1) != final_type)
            unsigned1 = TREE_UNSIGNED (TREE_TYPE (op1));

          /* Now UNSIGNED0 is 1 if ARG0 zero-extends to FINAL_TYPE.  */

          /* For bitwise operations, signedness of nominal type
             does not matter.  Consider only how operands were extended.  */
          if (shorten == -1)
            uns = unsigned0;

          /* Note that in all three cases below we refrain from optimizing
             an unsigned operation on sign-extended args.
             That would not be valid.  */

          /* Both args variable: if both extended in same way
             from same width, do it in that width.
             Do it unsigned if args were zero-extended.  */
          if ((TYPE_PRECISION (TREE_TYPE (arg0))
               < TYPE_PRECISION (result_type))
              && (TYPE_PRECISION (TREE_TYPE (arg1))
                  == TYPE_PRECISION (TREE_TYPE (arg0)))
              && unsigned0 == unsigned1
              && (unsigned0 || !uns))
            result_type
              = signed_or_unsigned_type (unsigned0,
                                         common_type (TREE_TYPE (arg0),
                                                      TREE_TYPE (arg1)));
          else if (TREE_CODE (arg0) == INTEGER_CST
                   && (unsigned1 || !uns)
                   && (TYPE_PRECISION (TREE_TYPE (arg1))
                       < TYPE_PRECISION (result_type))
                   && (type = signed_or_unsigned_type (unsigned1,
                                                       TREE_TYPE (arg1)),
                       int_fits_type_p (arg0, type)))
            result_type = type;
          else if (TREE_CODE (arg1) == INTEGER_CST
                   && (unsigned0 || !uns)
                   && (TYPE_PRECISION (TREE_TYPE (arg0))
                       < TYPE_PRECISION (result_type))
                   && (type = signed_or_unsigned_type (unsigned0,
                                                       TREE_TYPE (arg0)),
                       int_fits_type_p (arg1, type)))
            result_type = type;
        }

      /* Shifts can be shortened if shifting right.  */

      if (short_shift)
        {
          int unsigned_arg;
          tree arg0 = get_narrower (op0, &unsigned_arg);

          final_type = result_type;

          if (arg0 == op0 && final_type == TREE_TYPE (op0))
            unsigned_arg = TREE_UNSIGNED (TREE_TYPE (op0));

          if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
              /* We can shorten only if the shift count is less than the
                 number of bits in the smaller type size.  */
              && TREE_INT_CST_HIGH (op1) == 0
              && TYPE_PRECISION (TREE_TYPE (arg0)) > TREE_INT_CST_LOW (op1)
              /* If arg is sign-extended and then unsigned-shifted,
                 we can simulate this with a signed shift in arg's type
                 only if the extended result is at least twice as wide
                 as the arg.  Otherwise, the shift could use up all the
                 ones made by sign-extension and bring in zeros.
                 We can't optimize that case at all, but in most machines
                 it never happens because available widths are 2**N.  */
              && (!TREE_UNSIGNED (final_type)
                  || unsigned_arg
                  || (((unsigned) 2 * TYPE_PRECISION (TREE_TYPE (arg0)))
                      <= TYPE_PRECISION (result_type))))
            {
              /* Do an unsigned shift if the operand was zero-extended.  */
              result_type
                = signed_or_unsigned_type (unsigned_arg,
                                           TREE_TYPE (arg0));
              /* Convert value-to-be-shifted to that type.  */
              if (TREE_TYPE (op0) != result_type)
                op0 = cp_convert (result_type, op0);
              converted = 1;
            }
        }

      /* Comparison operations are shortened too but differently.
         They identify themselves by setting short_compare = 1.  */

      if (short_compare)
        {
          /* Don't write &op0, etc., because that would prevent op0
             from being kept in a register.
             Instead, make copies of the our local variables and
             pass the copies by reference, then copy them back afterward.  */
          tree xop0 = op0, xop1 = op1, xresult_type = result_type;
          enum tree_code xresultcode = resultcode;
          tree val 
            = shorten_compare (&xop0, &xop1, &xresult_type, &xresultcode);
          if (val != 0)
            return cp_convert (boolean_type_node, val);
          op0 = xop0, op1 = xop1;
          converted = 1;
          resultcode = xresultcode;
        }

      if (short_compare && warn_sign_compare)
        {
          int op0_signed = ! TREE_UNSIGNED (TREE_TYPE (orig_op0));
          int op1_signed = ! TREE_UNSIGNED (TREE_TYPE (orig_op1));

          int unsignedp0, unsignedp1;
          tree primop0 = get_narrower (op0, &unsignedp0);
          tree primop1 = get_narrower (op1, &unsignedp1);

          /* Check for comparison of different enum types.  */
          if (TREE_CODE (TREE_TYPE (orig_op0)) == ENUMERAL_TYPE 
              && TREE_CODE (TREE_TYPE (orig_op1)) == ENUMERAL_TYPE 
              && TYPE_MAIN_VARIANT (TREE_TYPE (orig_op0))
                 != TYPE_MAIN_VARIANT (TREE_TYPE (orig_op1)))
            {
              cp_warning ("comparison between `%#T' and `%#T'", 
                          TREE_TYPE (orig_op0), TREE_TYPE (orig_op1));
            }

          /* Give warnings for comparisons between signed and unsigned
             quantities that may fail.  */
          /* Do the checking based on the original operand trees, so that
             casts will be considered, but default promotions won't be.  */

          /* Do not warn if the comparison is being done in a signed type,
             since the signed type will only be chosen if it can represent
             all the values of the unsigned type.  */
          if (! TREE_UNSIGNED (result_type))
            /* OK */;
          /* Do not warn if both operands are unsigned.  */
          else if (op0_signed == op1_signed)
            /* OK */;
          /* Do not warn if the signed quantity is an unsuffixed
             integer literal (or some static constant expression
             involving such literals) and it is non-negative.  */
          else if ((op0_signed && TREE_CODE (orig_op0) == INTEGER_CST
                    && tree_int_cst_sgn (orig_op0) >= 0)
                   || (op1_signed && TREE_CODE (orig_op1) == INTEGER_CST
                       && tree_int_cst_sgn (orig_op1) >= 0))
            /* OK */;
          /* Do not warn if the comparison is an equality operation,
             the unsigned quantity is an integral constant and it does
             not use the most significant bit of result_type.  */
          else if ((resultcode == EQ_EXPR || resultcode == NE_EXPR)
                   && ((op0_signed && TREE_CODE (orig_op1) == INTEGER_CST
                        && int_fits_type_p (orig_op1,
                                            signed_type (result_type)))
                        || (op1_signed && TREE_CODE (orig_op0) == INTEGER_CST
                            && int_fits_type_p (orig_op0,
                                                signed_type (result_type)))))
            /* OK */;
          else
            warning ("comparison between signed and unsigned");

          /* Warn if two unsigned values are being compared in a size
             larger than their original size, and one (and only one) is the
             result of a `~' operator.  This comparison will always fail.

             Also warn if one operand is a constant, and the constant does not
             have all bits set that are set in the ~ operand when it is
             extended.  */

          if ((TREE_CODE (primop0) == BIT_NOT_EXPR)
              ^ (TREE_CODE (primop1) == BIT_NOT_EXPR))
            {
              if (TREE_CODE (primop0) == BIT_NOT_EXPR)
                primop0 = get_narrower (TREE_OPERAND (op0, 0), &unsignedp0);
              if (TREE_CODE (primop1) == BIT_NOT_EXPR)
                primop1 = get_narrower (TREE_OPERAND (op1, 0), &unsignedp1);
              
              if (TREE_CODE (primop0) == INTEGER_CST
                  || TREE_CODE (primop1) == INTEGER_CST)
                {
                  tree primop;
                  HOST_WIDE_INT constant, mask;
                  int unsignedp;
                  unsigned bits;

                  if (TREE_CODE (primop0) == INTEGER_CST)
                    {
                      primop = primop1;
                      unsignedp = unsignedp1;
                      constant = TREE_INT_CST_LOW (primop0);
                    }
                  else
                    {
                      primop = primop0;
                      unsignedp = unsignedp0;
                      constant = TREE_INT_CST_LOW (primop1);
                    }

                  bits = TYPE_PRECISION (TREE_TYPE (primop));
                  if (bits < TYPE_PRECISION (result_type)
                      && bits < HOST_BITS_PER_LONG && unsignedp)
                    {
                      mask = (~ (HOST_WIDE_INT) 0) << bits;
                      if ((mask & constant) != mask)
                        warning ("comparison of promoted ~unsigned with constant");
                    }
                }
              else if (unsignedp0 && unsignedp1
                       && (TYPE_PRECISION (TREE_TYPE (primop0))
                           < TYPE_PRECISION (result_type))
                       && (TYPE_PRECISION (TREE_TYPE (primop1))
                           < TYPE_PRECISION (result_type)))
                warning ("comparison of promoted ~unsigned with unsigned");
            }
        }
    }

  /* At this point, RESULT_TYPE must be nonzero to avoid an error message.
     If CONVERTED is zero, both args will be converted to type RESULT_TYPE.
     Then the expression will be built.
     It will be given type FINAL_TYPE if that is nonzero;
     otherwise, it will be given type RESULT_TYPE.  */

  if (!result_type)
    {
      cp_error ("invalid operands `%T' and `%T' to binary `%O'",
                TREE_TYPE (orig_op0), TREE_TYPE (orig_op1), error_code);
      return error_mark_node;
    }

  /* Issue warnings about peculiar, but legal, uses of NULL.  */
  if (/* It's reasonable to use pointer values as operands of &&
         and ||, so NULL is no exception.  */
      !(code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
      && (/* If OP0 is NULL and OP1 is not a pointer, or vice versa.  */
          (orig_op0 == null_node
           && TREE_CODE (TREE_TYPE (op1)) != POINTER_TYPE)
          /* Or vice versa.  */
          || (orig_op1 == null_node
              && TREE_CODE (TREE_TYPE (op0)) != POINTER_TYPE)
          /* Or, both are NULL and the operation was not a comparison.  */
          || (orig_op0 == null_node && orig_op1 == null_node 
              && code != EQ_EXPR && code != NE_EXPR)))
    /* Some sort of arithmetic operation involving NULL was
       performed.  Note that pointer-difference and pointer-addition
       have already been handled above, and so we don't end up here in
       that case.  */
    cp_warning ("NULL used in arithmetic");

  if (! converted)
    {
      if (TREE_TYPE (op0) != result_type)
        op0 = cp_convert (result_type, op0); 
      if (TREE_TYPE (op1) != result_type)
        op1 = cp_convert (result_type, op1); 

      if (op0 == error_mark_node || op1 == error_mark_node)
        return error_mark_node;
    }

  if (build_type == NULL_TREE)
    build_type = result_type;

  {
    register tree result = build (resultcode, build_type, op0, op1);
    register tree folded;

    folded = fold (result);
    if (folded == result)
      TREE_CONSTANT (folded) = TREE_CONSTANT (op0) & TREE_CONSTANT (op1);
    if (final_type != 0)
      return cp_convert (final_type, folded);
    return folded;
  }
}
\f
/* Return a tree for the sum or difference (RESULTCODE says which)
   of pointer PTROP and integer INTOP.  */

static tree
pointer_int_sum (resultcode, ptrop, intop)
     enum tree_code resultcode;
     register tree ptrop, intop;
{
  tree size_exp;

  register tree result;
  register tree folded = fold (intop);

  /* The result is a pointer of the same type that is being added.  */

  register tree result_type = TREE_TYPE (ptrop);

  if (!complete_type_or_else (result_type, ptrop))
    return error_mark_node;

  if (TREE_CODE (TREE_TYPE (result_type)) == VOID_TYPE)
    {
      if (pedantic || warn_pointer_arith)
        pedwarn ("ANSI C++ forbids using pointer of type `void *' in arithmetic");
      size_exp = integer_one_node;
    }
  else if (TREE_CODE (TREE_TYPE (result_type)) == FUNCTION_TYPE)
    {
      if (pedantic || warn_pointer_arith)
        pedwarn ("ANSI C++ forbids using pointer to a function in arithmetic");
      size_exp = integer_one_node;
    }
  else if (TREE_CODE (TREE_TYPE (result_type)) == METHOD_TYPE)
    {
      if (pedantic || warn_pointer_arith)
        pedwarn ("ANSI C++ forbids using pointer to a method in arithmetic");
      size_exp = integer_one_node;
    }
  else if (TREE_CODE (TREE_TYPE (result_type)) == OFFSET_TYPE)
    {
      if (pedantic || warn_pointer_arith)
        pedwarn ("ANSI C++ forbids using pointer to a member in arithmetic");
      size_exp = integer_one_node;
    }
  else
    size_exp = size_in_bytes (complete_type (TREE_TYPE (result_type)));

  /* Needed to make OOPS V2R3 work.  */
  intop = folded;
  if (TREE_CODE (intop) == INTEGER_CST
      && TREE_INT_CST_LOW (intop) == 0
      && TREE_INT_CST_HIGH (intop) == 0)
    return ptrop;

  /* If what we are about to multiply by the size of the elements
     contains a constant term, apply distributive law
     and multiply that constant term separately.
     This helps produce common subexpressions.  */

  if ((TREE_CODE (intop) == PLUS_EXPR || TREE_CODE (intop) == MINUS_EXPR)
      && ! TREE_CONSTANT (intop)
      && TREE_CONSTANT (TREE_OPERAND (intop, 1))
      && TREE_CONSTANT (size_exp))
    {
      enum tree_code subcode = resultcode;
      if (TREE_CODE (intop) == MINUS_EXPR)
        subcode = (subcode == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR);
      ptrop = build_binary_op (subcode, ptrop, TREE_OPERAND (intop, 1));
      intop = TREE_OPERAND (intop, 0);
    }

  /* Convert the integer argument to a type the same size as sizetype
     so the multiply won't overflow spuriously.  */

  if (TYPE_PRECISION (TREE_TYPE (intop)) != TYPE_PRECISION (sizetype))
    intop = cp_convert (type_for_size (TYPE_PRECISION (sizetype), 0), intop);

  /* Replace the integer argument with a suitable product by the object size.
     Do this multiplication as signed, then convert to the appropriate
     pointer type (actually unsigned integral).  */

  intop = cp_convert (result_type,
                      build_binary_op (MULT_EXPR, intop,
                                       cp_convert (TREE_TYPE (intop),
                                                   size_exp)));

  /* Create the sum or difference.  */

  result = build (resultcode, result_type, ptrop, intop);

  folded = fold (result);
  if (folded == result)
    TREE_CONSTANT (folded) = TREE_CONSTANT (ptrop) & TREE_CONSTANT (intop);
  return folded;
}

/* Return a tree for the difference of pointers OP0 and OP1.
   The resulting tree has type int.  */

static tree
pointer_diff (op0, op1, ptrtype)
     register tree op0, op1;
     register tree ptrtype;
{
  register tree result, folded;
  tree restype = ptrdiff_type_node;
  tree target_type = TREE_TYPE (ptrtype);

  if (!complete_type_or_else (target_type, NULL_TREE))
    return error_mark_node;

  if (pedantic || warn_pointer_arith)
    {
      if (TREE_CODE (target_type) == VOID_TYPE)
        pedwarn ("ANSI C++ forbids using pointer of type `void *' in subtraction");
      if (TREE_CODE (target_type) == FUNCTION_TYPE)
        pedwarn ("ANSI C++ forbids using pointer to a function in subtraction");
      if (TREE_CODE (target_type) == METHOD_TYPE)
        pedwarn ("ANSI C++ forbids using pointer to a method in subtraction");
      if (TREE_CODE (target_type) == OFFSET_TYPE)
        pedwarn ("ANSI C++ forbids using pointer to a member in subtraction");
    }

  /* First do the subtraction as integers;
     then drop through to build the divide operator.  */

  op0 = build_binary_op (MINUS_EXPR, cp_convert (restype, op0),
                         cp_convert (restype, op1));

  /* This generates an error if op1 is a pointer to an incomplete type.  */
  if (TYPE_SIZE (TREE_TYPE (TREE_TYPE (op1))) == 0)
    error ("arithmetic on pointer to an incomplete type");

  op1 = ((TREE_CODE (target_type) == VOID_TYPE
          || TREE_CODE (target_type) == FUNCTION_TYPE
          || TREE_CODE (target_type) == METHOD_TYPE
          || TREE_CODE (target_type) == OFFSET_TYPE)
         ? integer_one_node
         : size_in_bytes (target_type));

  /* Do the division.  */

  result = build (EXACT_DIV_EXPR, restype, op0, cp_convert (restype, op1));

  folded = fold (result);
  if (folded == result)
    TREE_CONSTANT (folded) = TREE_CONSTANT (op0) & TREE_CONSTANT (op1);
  return folded;
}
\f
/* Handle the case of taking the address of a COMPONENT_REF.
   Called by `build_unary_op'.

   ARG is the COMPONENT_REF whose address we want.
   ARGTYPE is the pointer type that this address should have. */

static tree
build_component_addr (arg, argtype)
     tree arg, argtype;
{
  tree field = TREE_OPERAND (arg, 1);
  tree basetype = decl_type_context (field);
  tree rval = build_unary_op (ADDR_EXPR, TREE_OPERAND (arg, 0), 0);

  my_friendly_assert (TREE_CODE (field) == FIELD_DECL, 981018);

  if (DECL_C_BIT_FIELD (field))
    {
      cp_error ("attempt to take address of bit-field structure member `%D'",
                field);
      return error_mark_node;
    }

  if (TREE_CODE (field) == FIELD_DECL
      && TYPE_USES_COMPLEX_INHERITANCE (basetype))
    {
      /* Can't convert directly to ARGTYPE, since that
         may have the same pointer type as one of our
         baseclasses.  */
      rval = build1 (NOP_EXPR, argtype,
                     convert_pointer_to (basetype, rval));
      TREE_CONSTANT (rval) = TREE_CONSTANT (TREE_OPERAND (rval, 0));
    }
  else
    /* This conversion is harmless.  */
    rval = convert_force (argtype, rval, 0);

  if (! integer_zerop (DECL_FIELD_BITPOS (field)))
    {
      tree offset = size_binop (EASY_DIV_EXPR, DECL_FIELD_BITPOS (field),
                                size_int (BITS_PER_UNIT));
      int flag = TREE_CONSTANT (rval);
      offset = convert (sizetype, offset);
      rval = fold (build (PLUS_EXPR, argtype,
                          rval, cp_convert (argtype, offset)));
      TREE_CONSTANT (rval) = flag;
    }
  return rval;
}
   
/* Construct and perhaps optimize a tree representation
   for a unary operation.  CODE, a tree_code, specifies the operation
   and XARG is the operand.  */

tree
build_x_unary_op (code, xarg)
     enum tree_code code;
     tree xarg;
{
  if (processing_template_decl)
    return build_min_nt (code, xarg, NULL_TREE);

  /* & rec, on incomplete RECORD_TYPEs is the simple opr &, not an
     error message.  */
  if (code == ADDR_EXPR
      && TREE_CODE (xarg) != TEMPLATE_ID_EXPR
      && ((IS_AGGR_TYPE_CODE (TREE_CODE (TREE_TYPE (xarg)))
           && TYPE_SIZE (TREE_TYPE (xarg)) == NULL_TREE)
          || (TREE_CODE (xarg) == OFFSET_REF)))
    /* don't look for a function */;
  else
    {
      tree rval;

      rval = build_new_op (code, LOOKUP_NORMAL, xarg,
                           NULL_TREE, NULL_TREE);
      if (rval || code != ADDR_EXPR)
        return rval;
    }

  if (code == ADDR_EXPR)
    {
      if (TREE_CODE (xarg) == TARGET_EXPR)
        warning ("taking address of temporary");
    }

  return build_unary_op (code, xarg, 0);
}

/* Just like truthvalue_conversion, but we want a CLEANUP_POINT_EXPR.  */
   
tree
condition_conversion (expr)
     tree expr;
{
  tree t;
  if (processing_template_decl)
    return expr;
  t = perform_implicit_conversion (boolean_type_node, expr);
  t = fold (build1 (CLEANUP_POINT_EXPR, boolean_type_node, t));
  return t;
}
                               
/* C++: Must handle pointers to members.

   Perhaps type instantiation should be extended to handle conversion
   from aggregates to types we don't yet know we want?  (Or are those
   cases typically errors which should be reported?)

   NOCONVERT nonzero suppresses the default promotions
   (such as from short to int).  */

tree
build_unary_op (code, xarg, noconvert)
     enum tree_code code;
     tree xarg;
     int noconvert;
{
  /* No default_conversion here.  It causes trouble for ADDR_EXPR.  */
  register tree arg = xarg;
  register tree argtype = 0;
  const char *errstring = NULL;
  tree val;

  if (arg == error_mark_node)
    return error_mark_node;

  switch (code)
    {
    case CONVERT_EXPR:
      /* This is used for unary plus, because a CONVERT_EXPR
         is enough to prevent anybody from looking inside for
         associativity, but won't generate any code.  */
      if (!(arg = build_expr_type_conversion
            (WANT_ARITH | WANT_ENUM | WANT_POINTER, arg, 1)))
        errstring = "wrong type argument to unary plus";
      else
        {
          if (!noconvert)
           arg = default_conversion (arg);
          arg = build1 (NON_LVALUE_EXPR, TREE_TYPE (arg), arg);
          TREE_CONSTANT (arg) = TREE_CONSTANT (TREE_OPERAND (arg, 0));
        }
      break;

    case NEGATE_EXPR:
      if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, 1)))
        errstring = "wrong type argument to unary minus";
      else if (!noconvert)
        arg = default_conversion (arg);
      break;

    case BIT_NOT_EXPR:
      if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
        {
          code = CONJ_EXPR;
          if (!noconvert)
            arg = default_conversion (arg);
        }
      else if (!(arg = build_expr_type_conversion (WANT_INT | WANT_ENUM,
                                                   arg, 1)))
        errstring = "wrong type argument to bit-complement";
      else if (!noconvert)
        arg = default_conversion (arg);
      break;

    case ABS_EXPR:
      if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, 1)))
        errstring = "wrong type argument to abs";
      else if (!noconvert)
        arg = default_conversion (arg);
      break;

    case CONJ_EXPR:
      /* Conjugating a real value is a no-op, but allow it anyway.  */
      if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_ENUM, arg, 1)))
        errstring = "wrong type argument to conjugation";
      else if (!noconvert)
        arg = default_conversion (arg);
      break;

    case TRUTH_NOT_EXPR:
      arg = cp_convert (boolean_type_node, arg);
      val = invert_truthvalue (arg);
      if (arg != error_mark_node)
        return val;
      errstring = "in argument to unary !";
      break;

    case NOP_EXPR:
      break;
      
    case REALPART_EXPR:
      if (TREE_CODE (arg) == COMPLEX_CST)
        return TREE_REALPART (arg);
      else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
        return fold (build1 (REALPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
      else
        return arg;

    case IMAGPART_EXPR:
      if (TREE_CODE (arg) == COMPLEX_CST)
        return TREE_IMAGPART (arg);
      else if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
        return fold (build1 (IMAGPART_EXPR, TREE_TYPE (TREE_TYPE (arg)), arg));
      else
        return cp_convert (TREE_TYPE (arg), integer_zero_node);
      
    case PREINCREMENT_EXPR:
    case POSTINCREMENT_EXPR:
    case PREDECREMENT_EXPR:
    case POSTDECREMENT_EXPR:
      /* Handle complex lvalues (when permitted)
         by reduction to simpler cases.  */

      val = unary_complex_lvalue (code, arg);
      if (val != 0)
        return val;

      /* Increment or decrement the real part of the value,
         and don't change the imaginary part.  */
      if (TREE_CODE (TREE_TYPE (arg)) == COMPLEX_TYPE)
        {
          tree real, imag;

          arg = stabilize_reference (arg);
          real = build_unary_op (REALPART_EXPR, arg, 1);
          imag = build_unary_op (IMAGPART_EXPR, arg, 1);
          return build (COMPLEX_EXPR, TREE_TYPE (arg),
                        build_unary_op (code, real, 1), imag);
        }

      /* Report invalid types.  */

      if (!(arg = build_expr_type_conversion (WANT_ARITH | WANT_POINTER,
                                              arg, 1)))
        {
          if (code == PREINCREMENT_EXPR)
            errstring ="no pre-increment operator for type";
          else if (code == POSTINCREMENT_EXPR)
            errstring ="no post-increment operator for type";
          else if (code == PREDECREMENT_EXPR)
            errstring ="no pre-decrement operator for type";
          else
            errstring ="no post-decrement operator for type";
          break;
        }

      /* Report something read-only.  */

      if (CP_TYPE_CONST_P (TREE_TYPE (arg))
          || TREE_READONLY (arg))
        readonly_error (arg, ((code == PREINCREMENT_EXPR
                               || code == POSTINCREMENT_EXPR)
                              ? "increment" : "decrement"),
                        0);

      {
        register tree inc;
        tree result_type = TREE_TYPE (arg);

        arg = get_unwidened (arg, 0);
        argtype = TREE_TYPE (arg);

        /* ARM $5.2.5 last annotation says this should be forbidden.  */
        if (TREE_CODE (argtype) == ENUMERAL_TYPE)
          pedwarn ("ANSI C++ forbids %sing an enum",
                   (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
                   ? "increment" : "decrement");
            
        /* Compute the increment.  */

        if (TREE_CODE (argtype) == POINTER_TYPE)
          {
            enum tree_code tmp = TREE_CODE (TREE_TYPE (argtype));
            if (TYPE_SIZE (complete_type (TREE_TYPE (argtype))) == 0)
              cp_error ("cannot %s a pointer to incomplete type `%T'",
                        ((code == PREINCREMENT_EXPR
                          || code == POSTINCREMENT_EXPR)
                         ? "increment" : "decrement"), TREE_TYPE (argtype));
            else if ((pedantic || warn_pointer_arith)
                     && (tmp == FUNCTION_TYPE || tmp == METHOD_TYPE
                         || tmp == VOID_TYPE || tmp == OFFSET_TYPE))
              cp_pedwarn ("ANSI C++ forbids %sing a pointer of type `%T'",
                          ((code == PREINCREMENT_EXPR
                            || code == POSTINCREMENT_EXPR)
                           ? "increment" : "decrement"), argtype);
            inc = c_sizeof_nowarn (TREE_TYPE (argtype));
          }
        else
          inc = integer_one_node;

        inc = cp_convert (argtype, inc);

        /* Handle incrementing a cast-expression.  */

        switch (TREE_CODE (arg))
          {
          case NOP_EXPR:
          case CONVERT_EXPR:
          case FLOAT_EXPR:
          case FIX_TRUNC_EXPR:
          case FIX_FLOOR_EXPR:
          case FIX_ROUND_EXPR:
          case FIX_CEIL_EXPR:
            {
              tree incremented, modify, value, compound;
              if (! lvalue_p (arg) && pedantic)
                pedwarn ("cast to non-reference type used as lvalue");
              arg = stabilize_reference (arg);
              if (code == PREINCREMENT_EXPR || code == PREDECREMENT_EXPR)
                value = arg;
              else
                value = save_expr (arg);
              incremented = build (((code == PREINCREMENT_EXPR
                                     || code == POSTINCREMENT_EXPR)
                                    ? PLUS_EXPR : MINUS_EXPR),
                                   argtype, value, inc);

              modify = build_modify_expr (arg, NOP_EXPR, incremented);
              compound = build (COMPOUND_EXPR, TREE_TYPE (arg), modify, value);

              /* Eliminate warning about unused result of + or -.  */
              TREE_NO_UNUSED_WARNING (compound) = 1;
              return compound;
            }

          default:
            break;
          }

        /* Complain about anything else that is not a true lvalue.  */
        if (!lvalue_or_else (arg, ((code == PREINCREMENT_EXPR
                                    || code == POSTINCREMENT_EXPR)
                                   ? "increment" : "decrement")))
          return error_mark_node;

        /* Forbid using -- on `bool'.  */
        if (TREE_TYPE (arg) == boolean_type_node)
          {
            if (code == POSTDECREMENT_EXPR || code == PREDECREMENT_EXPR)
              {
                cp_error ("invalid use of `--' on bool variable `%D'", arg);
                return error_mark_node;
              }
#if 0
            /* This will only work if someone can convince Kenner to accept
               my patch to expand_increment. (jason)  */
            val = build (code, TREE_TYPE (arg), arg, inc);
#else
            if (code == POSTINCREMENT_EXPR)
              {
                arg = stabilize_reference (arg);
                val = build (MODIFY_EXPR, TREE_TYPE (arg), arg,
                             boolean_true_node);
                arg = save_expr (arg);
                val = build (COMPOUND_EXPR, TREE_TYPE (arg), val, arg);
                val = build (COMPOUND_EXPR, TREE_TYPE (arg), arg, val);
              }
            else
              val = build (MODIFY_EXPR, TREE_TYPE (arg), arg,
                           boolean_true_node);
#endif
          }
        else
          val = build (code, TREE_TYPE (arg), arg, inc);

        TREE_SIDE_EFFECTS (val) = 1;
        return cp_convert (result_type, val);
      }

    case ADDR_EXPR:
      /* Note that this operation never does default_conversion
         regardless of NOCONVERT.  */

      argtype = lvalue_type (arg);
      if (TREE_CODE (argtype) == REFERENCE_TYPE)
        {
          arg = build1
            (CONVERT_EXPR,
             build_pointer_type (TREE_TYPE (argtype)), arg);
          TREE_CONSTANT (arg) = TREE_CONSTANT (TREE_OPERAND (arg, 0));
          return arg;
        }
      else if (pedantic && DECL_MAIN_P (arg))
        /* ARM $3.4 */
        pedwarn ("taking address of function `main'");

      /* Let &* cancel out to simplify resulting code.  */
      if (TREE_CODE (arg) == INDIRECT_REF)
        {
          /* We don't need to have `current_class_ptr' wrapped in a
             NON_LVALUE_EXPR node.  */
          if (arg == current_class_ref)
            return current_class_ptr;

          arg = TREE_OPERAND (arg, 0);
          if (TREE_CODE (TREE_TYPE (arg)) == REFERENCE_TYPE)
            {
              arg = build1
                (CONVERT_EXPR,
                 build_pointer_type (TREE_TYPE (TREE_TYPE (arg))), arg);
              TREE_CONSTANT (arg) = TREE_CONSTANT (TREE_OPERAND (arg, 0));
            }
          else if (lvalue_p (arg))
            /* Don't let this be an lvalue.  */
            return non_lvalue (arg);
          return arg;
        }

      /* For &x[y], return x+y */
      if (TREE_CODE (arg) == ARRAY_REF)
        {
          if (mark_addressable (TREE_OPERAND (arg, 0)) == 0)
            return error_mark_node;
          return build_binary_op (PLUS_EXPR, TREE_OPERAND (arg, 0),
                                  TREE_OPERAND (arg, 1));
        }

      /* Uninstantiated types are all functions.  Taking the
         address of a function is a no-op, so just return the
         argument.  */

      if (TREE_CODE (arg) == IDENTIFIER_NODE
          && IDENTIFIER_OPNAME_P (arg))
        {
          my_friendly_abort (117);
          /* We don't know the type yet, so just work around the problem.
             We know that this will resolve to an lvalue.  */
          return build1 (ADDR_EXPR, unknown_type_node, arg);
        }

      if (TREE_CODE (arg) == COMPONENT_REF && type_unknown_p (arg)
          && OVL_NEXT (TREE_OPERAND (arg, 1)) == NULL_TREE)
        {
          /* They're trying to take the address of a unique non-static
             member function.  This is ill-formed, but let's try to DTRT.
             Note: We only handle unique functions here because we don't
             want to complain if there's a static overload; non-unique
             cases will be handled by instantiate_type.  But we need to
             handle this case here to allow casts on the resulting PMF.  */

          tree base = TREE_TYPE (TREE_OPERAND (arg, 0));
          tree name = DECL_NAME (OVL_CURRENT (TREE_OPERAND (arg, 1)));

          if (! flag_ms_extensions)
            {
              if (current_class_type
                  && TREE_OPERAND (arg, 0) == current_class_ref)
                /* An expression like &memfn.  */
                pedwarn ("taking the address of a non-static member function");
              else
                pedwarn ("taking the address of a bound member function");

              cp_pedwarn
                ("  to form a pointer to member function, say `&%T::%D'",
                 base, name);
            }

          arg = build_offset_ref (base, name);
        }

      if (type_unknown_p (arg))
        return build1 (ADDR_EXPR, unknown_type_node, arg);

      /* Handle complex lvalues (when permitted)
         by reduction to simpler cases.  */
      val = unary_complex_lvalue (code, arg);
      if (val != 0)
        return val;

      switch (TREE_CODE (arg))
        {
        case NOP_EXPR:
        case CONVERT_EXPR:
        case FLOAT_EXPR:
        case FIX_TRUNC_EXPR:
        case FIX_FLOOR_EXPR:
        case FIX_ROUND_EXPR:
        case FIX_CEIL_EXPR:
          if (! lvalue_p (arg) && pedantic)
            pedwarn ("taking the address of a cast to non-reference type");
          break;
          
        default:
          break;
        }

      /* Allow the address of a constructor if all the elements
         are constant.  */
      if (TREE_CODE (arg) == CONSTRUCTOR && TREE_HAS_CONSTRUCTOR (arg)
          && TREE_CONSTANT (arg))
        ;
      /* Anything not already handled and not a true memory reference
         is an error.  */
      else if (TREE_CODE (argtype) != FUNCTION_TYPE
               && TREE_CODE (argtype) != METHOD_TYPE
               && !lvalue_or_else (arg, "unary `&'"))
        return error_mark_node;

      if (argtype != error_mark_node)
        argtype = build_pointer_type (argtype);

      if (mark_addressable (arg) == 0)
        return error_mark_node;

      {
        tree addr;

        if (TREE_CODE (arg) == COMPONENT_REF)
          addr = build_component_addr (arg, argtype);
        else
          addr = build1 (ADDR_EXPR, argtype, arg);

        /* Address of a static or external variable or
           function counts as a constant */
        if (staticp (arg))
          TREE_CONSTANT (addr) = 1;

        if (TREE_CODE (argtype) == POINTER_TYPE
            && TREE_CODE (TREE_TYPE (argtype)) == METHOD_TYPE)
          {
            build_ptrmemfunc_type (argtype);
            addr = build_ptrmemfunc (argtype, addr, 0);
          }

        return addr;
      }

    default:
      break;
    }

  if (!errstring)
    {
      if (argtype == 0)
        argtype = TREE_TYPE (arg);
      return fold (build1 (code, argtype, arg));
    }

  error (errstring);
  return error_mark_node;
}

#if 0
/* If CONVERSIONS is a conversion expression or a nested sequence of such,
   convert ARG with the same conversions in the same order
   and return the result.  */

static tree
convert_sequence (conversions, arg)
     tree conversions;
     tree arg;
{
  switch (TREE_CODE (conversions))
    {
    case NOP_EXPR:
    case CONVERT_EXPR:
    case FLOAT_EXPR:
    case FIX_TRUNC_EXPR:
    case FIX_FLOOR_EXPR:
    case FIX_ROUND_EXPR:
    case FIX_CEIL_EXPR:
      return cp_convert (TREE_TYPE (conversions),
                         convert_sequence (TREE_OPERAND (conversions, 0),
                                           arg));

    default:
      return arg;
    }
}
#endif

/* Apply unary lvalue-demanding operator CODE to the expression ARG
   for certain kinds of expressions which are not really lvalues
   but which we can accept as lvalues.

   If ARG is not a kind of expression we can handle, return zero.  */
   
tree
unary_complex_lvalue (code, arg)
     enum tree_code code;
     tree arg;
{
  /* Handle (a, b) used as an "lvalue".  */
  if (TREE_CODE (arg) == COMPOUND_EXPR)
    {
      tree real_result = build_unary_op (code, TREE_OPERAND (arg, 1), 0);
      return build (COMPOUND_EXPR, TREE_TYPE (real_result),
                    TREE_OPERAND (arg, 0), real_result);
    }

  /* Handle (a ? b : c) used as an "lvalue".  */
  if (TREE_CODE (arg) == COND_EXPR
      || TREE_CODE (arg) == MIN_EXPR || TREE_CODE (arg) == MAX_EXPR)
    return rationalize_conditional_expr (code, arg);

  if (TREE_CODE (arg) == MODIFY_EXPR
      || TREE_CODE (arg) == PREINCREMENT_EXPR
      || TREE_CODE (arg) == PREDECREMENT_EXPR)
    return unary_complex_lvalue
      (code, build (COMPOUND_EXPR, TREE_TYPE (TREE_OPERAND (arg, 0)),
                    arg, TREE_OPERAND (arg, 0)));

  if (code != ADDR_EXPR)
    return 0;

  /* Handle (a = b) used as an "lvalue" for `&'.  */
  if (TREE_CODE (arg) == MODIFY_EXPR
      || TREE_CODE (arg) == INIT_EXPR)
    {
      tree real_result = build_unary_op (code, TREE_OPERAND (arg, 0), 0);
      arg = build (COMPOUND_EXPR, TREE_TYPE (real_result), arg, real_result);
      TREE_NO_UNUSED_WARNING (arg) = 1;
      return arg;
    }

  if (TREE_CODE (TREE_TYPE (arg)) == FUNCTION_TYPE
      || TREE_CODE (TREE_TYPE (arg)) == METHOD_TYPE
      || TREE_CODE (TREE_TYPE (arg)) == OFFSET_TYPE)
    {
      /* The representation of something of type OFFSET_TYPE
         is really the representation of a pointer to it.
         Here give the representation its true type.  */
      tree t;

      my_friendly_assert (TREE_CODE (arg) != SCOPE_REF, 313);

      if (TREE_CODE (arg) != OFFSET_REF)
        return 0;

      t = TREE_OPERAND (arg, 1);

      /* Check all this code for right semantics.  */   
      if (TREE_CODE (t) == FUNCTION_DECL)
        {
          if (DECL_DESTRUCTOR_P (t))
            cp_error ("taking address of destructor");
          return build_unary_op (ADDR_EXPR, t, 0);
        }
      if (TREE_CODE (t) == VAR_DECL)
        return build_unary_op (ADDR_EXPR, t, 0);
      else
        {
          tree type;

          if (TREE_OPERAND (arg, 0)
              && ! is_dummy_object (TREE_OPERAND (arg, 0))
              && TREE_CODE (t) != FIELD_DECL)
            {
              cp_error ("taking address of bound pointer-to-member expression");
              return error_mark_node;
            }

          type = build_offset_type (DECL_FIELD_CONTEXT (t), TREE_TYPE (t));
          type = build_pointer_type (type);

          t = make_ptrmem_cst (type, TREE_OPERAND (arg, 1));
          return t;
        }
    }

  
  /* We permit compiler to make function calls returning
     objects of aggregate type look like lvalues.  */
  {
    tree targ = arg;

    if (TREE_CODE (targ) == SAVE_EXPR)
      targ = TREE_OPERAND (targ, 0);

    if (TREE_CODE (targ) == CALL_EXPR && IS_AGGR_TYPE (TREE_TYPE (targ)))
      {
        if (TREE_CODE (arg) == SAVE_EXPR)
          targ = arg;
        else
          targ = build_cplus_new (TREE_TYPE (arg), arg);
        return build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (arg)), targ);
      }

    if (TREE_CODE (arg) == SAVE_EXPR && TREE_CODE (targ) == INDIRECT_REF)
      return build (SAVE_EXPR, build_pointer_type (TREE_TYPE (arg)),
                     TREE_OPERAND (targ, 0), current_function_decl, NULL);
  }

  /* Don't let anything else be handled specially.  */
  return 0;
}
\f
/* Mark EXP saying that we need to be able to take the
   address of it; it should not be allocated in a register.
   Value is 1 if successful.

   C++: we do not allow `current_class_ptr' to be addressable.  */

int
mark_addressable (exp)
     tree exp;
{
  register tree x = exp;

  if (TREE_ADDRESSABLE (x) == 1)
    return 1;

  while (1)
    switch (TREE_CODE (x))
      {
      case ADDR_EXPR:
      case COMPONENT_REF:
      case ARRAY_REF:
      case REALPART_EXPR:
      case IMAGPART_EXPR:
        x = TREE_OPERAND (x, 0);
        break;

      case PARM_DECL:
        if (x == current_class_ptr)
          {
            if (! flag_this_is_variable)
              error ("address of `this' not available");
            TREE_ADDRESSABLE (x) = 1; /* so compiler doesn't die later */
            put_var_into_stack (x);
            return 1;
          }
      case VAR_DECL:
        if (TREE_STATIC (x) && TREE_READONLY (x)
            && DECL_RTL (x) != 0
            && ! DECL_IN_MEMORY_P (x))
          {
            /* We thought this would make a good constant variable,
               but we were wrong.  */
            push_permanent_obstack ();

            TREE_ASM_WRITTEN (x) = 0;
            DECL_RTL (x) = 0;
            rest_of_decl_compilation (x, 0, 
                                      !DECL_FUNCTION_SCOPE_P (x),
                                      0);
            TREE_ADDRESSABLE (x) = 1;

            pop_obstacks ();

            return 1;
          }
        /* Caller should not be trying to mark initialized
           constant fields addressable.  */
        my_friendly_assert (DECL_LANG_SPECIFIC (x) == 0
                            || DECL_IN_AGGR_P (x) == 0
                            || TREE_STATIC (x)
                            || DECL_EXTERNAL (x), 314);

      case CONST_DECL:
      case RESULT_DECL:
        if (DECL_REGISTER (x) && !TREE_ADDRESSABLE (x)
            && !DECL_ARTIFICIAL (x) && extra_warnings)
          cp_warning ("address requested for `%D', which is declared `register'",
                      x);
        TREE_ADDRESSABLE (x) = 1;
        TREE_USED (x) = 1;
        if (current_function && expanding_p)
          put_var_into_stack (x);
        return 1;

      case FUNCTION_DECL:
        if (DECL_LANG_SPECIFIC (x) != 0)
          {
            x = DECL_MAIN_VARIANT (x);
            /* We have to test both conditions here.  The first may be
               non-zero in the case of processing a default function.  The
               second may be non-zero in the case of a template function.  */
            if (DECL_TEMPLATE_INFO (x) && !DECL_TEMPLATE_SPECIALIZATION (x))
              mark_used (x);
          }
        TREE_ADDRESSABLE (x) = 1;
        TREE_USED (x) = 1;
        TREE_ADDRESSABLE (DECL_ASSEMBLER_NAME (x)) = 1;
        return 1;

      case CONSTRUCTOR:
        TREE_ADDRESSABLE (x) = 1;
        return 1;

      case TARGET_EXPR:
        TREE_ADDRESSABLE (x) = 1;
        mark_addressable (TREE_OPERAND (x, 0));
        return 1;

      default:
        return 1;
    }
}
\f
/* Build and return a conditional expression IFEXP ? OP1 : OP2.  */

tree
build_x_conditional_expr (ifexp, op1, op2)
     tree ifexp, op1, op2;
{
  if (processing_template_decl)
    return build_min_nt (COND_EXPR, ifexp, op1, op2);

  return build_conditional_expr (ifexp, op1, op2);
}
\f
/* Handle overloading of the ',' operator when needed.  Otherwise,
   this function just builds an expression list.  */

tree
build_x_compound_expr (list)
     tree list;
{
  tree rest = TREE_CHAIN (list);
  tree result;

  if (processing_template_decl)
    return build_min_nt (COMPOUND_EXPR, list, NULL_TREE);

  if (rest == NULL_TREE)
    return build_compound_expr (list);

  result = build_opfncall (COMPOUND_EXPR, LOOKUP_NORMAL,
                           TREE_VALUE (list), TREE_VALUE (rest), NULL_TREE);
  if (result)
    return build_x_compound_expr (tree_cons (NULL_TREE, result,
                                                  TREE_CHAIN (rest)));

  if (! TREE_SIDE_EFFECTS (TREE_VALUE (list)))
    {
      /* FIXME: This test should be in the implicit cast to void of the LHS. */
      /* the left-hand operand of a comma expression is like an expression
         statement: we should warn if it doesn't have any side-effects,
         unless it was explicitly cast to (void).  */
      if ((extra_warnings || warn_unused)
           && !(TREE_CODE (TREE_VALUE(list)) == CONVERT_EXPR
                && TREE_TYPE (TREE_VALUE(list)) == void_type_node))
        warning("left-hand operand of comma expression has no effect");
    }
#if 0 /* this requires a gcc backend patch to export warn_if_unused_value */
  else if (warn_unused)
    warn_if_unused_value (TREE_VALUE(list));
#endif

  return build_compound_expr
    (tree_cons (NULL_TREE, TREE_VALUE (list),
                     build_expr_list (NULL_TREE,
                                      build_x_compound_expr (rest))));
}

/* Given a list of expressions, return a compound expression
   that performs them all and returns the value of the last of them.  */

tree
build_compound_expr (list)
     tree list;
{
  register tree rest;
  tree first;

  if (TREE_READONLY_DECL_P (TREE_VALUE (list)))
    TREE_VALUE (list) = decl_constant_value (TREE_VALUE (list));

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

  first = TREE_VALUE (list);
  first = convert_to_void (first, "lhs of comma");
  if (first == error_mark_node)
    return error_mark_node;
  
  rest = build_compound_expr (TREE_CHAIN (list));
  if (rest == error_mark_node)
    return error_mark_node;

  /* When pedantic, a compound expression cannot be a constant expression.  */
  if (! TREE_SIDE_EFFECTS (first) && ! pedantic)
    return rest;

  return build (COMPOUND_EXPR, TREE_TYPE (rest),
                break_out_cleanups (first), rest);
}

tree
build_static_cast (type, expr)
   tree type, expr;
{
  tree intype, binfo;
  int ok;

  if (type == error_mark_node || expr == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (expr) == OFFSET_REF)
    expr = resolve_offset_ref (expr);

  if (processing_template_decl)
    {
      tree t = build_min (STATIC_CAST_EXPR, type, expr); 
      return t;
    }

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

  if (TREE_CODE (type) == VOID_TYPE)
    {
      expr = convert_to_void (expr, /*implicit=*/NULL);
      return expr;
    }

  if (TREE_CODE (type) == REFERENCE_TYPE)
    return (convert_from_reference
            (convert_to_reference (type, expr, CONV_STATIC|CONV_IMPLICIT,
                                   LOOKUP_COMPLAIN, NULL_TREE)));

  if (IS_AGGR_TYPE (type))
    return build_cplus_new
      (type, (build_method_call
              (NULL_TREE, ctor_identifier, build_expr_list (NULL_TREE, expr),
               TYPE_BINFO (type), LOOKUP_NORMAL)));

  expr = decay_conversion (expr);
  intype = TREE_TYPE (expr);

  /* FIXME handle casting to array type.  */

  ok = 0;
  if (can_convert_arg (type, intype, expr))
    ok = 1;
  else if (TYPE_PTROB_P (type) && TYPE_PTROB_P (intype))
    {
      tree binfo;
      if (IS_AGGR_TYPE (TREE_TYPE (type)) && IS_AGGR_TYPE (TREE_TYPE (intype))
          && at_least_as_qualified_p (TREE_TYPE (type),
                                      TREE_TYPE (intype))
          && (binfo = get_binfo (TREE_TYPE (intype), TREE_TYPE (type), 0))
          && ! TREE_VIA_VIRTUAL (binfo))
        ok = 1;
    }
  else if (TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
    {
      if (same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (type))),
                       TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (intype))))
          && at_least_as_qualified_p (TREE_TYPE (TREE_TYPE (type)),
                                      TREE_TYPE (TREE_TYPE (intype)))
          && (binfo = get_binfo (TYPE_OFFSET_BASETYPE (TREE_TYPE (type)),
                                 TYPE_OFFSET_BASETYPE (TREE_TYPE (intype)), 0))
          && ! TREE_VIA_VIRTUAL (binfo))
        ok = 1;
    }
  else if (TREE_CODE (intype) != BOOLEAN_TYPE
           && TREE_CODE (type) != ARRAY_TYPE
           && TREE_CODE (type) != FUNCTION_TYPE
           && can_convert (intype, type))
    ok = 1;

  /* [expr.static.cast]

     The static_cast operator shall not be used to cast away
     constnes.  */
  if (ok && casts_away_constness (intype, type))
    {
      cp_error ("static_cast from `%T' to `%T' casts away constness",
                intype, type);
      return error_mark_node;
    }

  if (ok)
    return build_c_cast (type, expr);

  cp_error ("static_cast from `%T' to `%T'", intype, type);
  return error_mark_node;
}

tree
build_reinterpret_cast (type, expr)
   tree type, expr;
{
  tree intype;

  if (type == error_mark_node || expr == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (expr) == OFFSET_REF)
    expr = resolve_offset_ref (expr);

  if (processing_template_decl)
    {
      tree t = build_min (REINTERPRET_CAST_EXPR, type, expr);
      return t;
    }

  if (TREE_CODE (type) != REFERENCE_TYPE)
    {
      expr = decay_conversion (expr);

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

  intype = TREE_TYPE (expr);

  if (TREE_CODE (type) == REFERENCE_TYPE)
    {
      if (! real_lvalue_p (expr))
        {
          cp_error ("reinterpret_cast from `%T' rvalue to `%T'", intype, type);
          return error_mark_node;
        }
      expr = build_unary_op (ADDR_EXPR, expr, 0);
      if (expr != error_mark_node)
        expr = build_reinterpret_cast
          (build_pointer_type (TREE_TYPE (type)), expr);
      if (expr != error_mark_node)
        expr = build_indirect_ref (expr, 0);
      return expr;
    }
  else if (same_type_p (TYPE_MAIN_VARIANT (intype), 
                        TYPE_MAIN_VARIANT (type)))
    return build_static_cast (type, expr);

  if (TYPE_PTR_P (type) && (TREE_CODE (intype) == INTEGER_TYPE
                            || TREE_CODE (intype) == ENUMERAL_TYPE))
    /* OK */;
  else if (TREE_CODE (type) == INTEGER_TYPE && TYPE_PTR_P (intype))
    {
      if (TYPE_PRECISION (type) < TYPE_PRECISION (intype))
        cp_pedwarn ("reinterpret_cast from `%T' to `%T' loses precision",
                    intype, type);
    }
  else if ((TYPE_PTRFN_P (type) && TYPE_PTRFN_P (intype))
           || (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
    {
      if (TREE_READONLY_DECL_P (expr))
        expr = decl_constant_value (expr);
      return fold (build1 (NOP_EXPR, type, expr));
    }
  else if ((TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype))
           || (TYPE_PTROBV_P (type) && TYPE_PTROBV_P (intype)))
    {
      if (! comp_ptr_ttypes_reinterpret (TREE_TYPE (type), TREE_TYPE (intype)))
        cp_pedwarn ("reinterpret_cast from `%T' to `%T' casts away const (or volatile)",
                    intype, type);

      if (TREE_READONLY_DECL_P (expr))
        expr = decl_constant_value (expr);
      return fold (build1 (NOP_EXPR, type, expr));
    }
  else if ((TYPE_PTRFN_P (type) && TYPE_PTROBV_P (intype))
           || (TYPE_PTRFN_P (intype) && TYPE_PTROBV_P (type)))
    {
      pedwarn ("ANSI C++ forbids casting between pointers to functions and objects");
      if (TREE_READONLY_DECL_P (expr))
        expr = decl_constant_value (expr);
      return fold (build1 (NOP_EXPR, type, expr));
    }
  else
    {
      cp_error ("reinterpret_cast from `%T' to `%T'", intype, type);
      return error_mark_node;
    }
      
  return cp_convert (type, expr);
}

tree
build_const_cast (type, expr)
   tree type, expr;
{
  tree intype;

  if (type == error_mark_node || expr == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (expr) == OFFSET_REF)
    expr = resolve_offset_ref (expr);

  if (processing_template_decl)
    {
      tree t = build_min (CONST_CAST_EXPR, type, expr);
      return t;
    }

  if (!POINTER_TYPE_P (type))
    {
      cp_error ("`%T' is not a pointer, reference, or pointer-to-data-member type",
                type);
      cp_error ("as required by const_cast");
    }
  else if (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE)
    {
      cp_error ("`%T' is a pointer or reference to a function type",
                type);
      cp_error ("which is forbidden by const_cast");
      return error_mark_node;
    }

  if (TREE_CODE (type) != REFERENCE_TYPE)
    {
      expr = decay_conversion (expr);

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

  intype = TREE_TYPE (expr);

  if (same_type_p (TYPE_MAIN_VARIANT (intype), TYPE_MAIN_VARIANT (type)))
    return build_static_cast (type, expr);
  else if (TREE_CODE (type) == REFERENCE_TYPE)
    {
      if (! real_lvalue_p (expr))
        {
          cp_error ("const_cast from `%T' rvalue to `%T'", intype, type);
          return error_mark_node;
        }

      if (comp_ptr_ttypes_const (TREE_TYPE (type), intype))
        {
          expr = build_unary_op (ADDR_EXPR, expr, 0);
          expr = build1 (NOP_EXPR, type, expr);
          return convert_from_reference (expr);
        }
    }
  else if (TREE_CODE (type) == POINTER_TYPE
           && TREE_CODE (intype) == POINTER_TYPE
           && comp_ptr_ttypes_const (TREE_TYPE (type), TREE_TYPE (intype)))
    return cp_convert (type, expr);

  cp_error ("const_cast from `%T' to `%T'", intype, type);
  return error_mark_node;
}

/* Build an expression representing a cast to type TYPE of expression EXPR.

   ALLOW_NONCONVERTING is true if we should allow non-converting constructors
   when doing the cast.  */

tree
build_c_cast (type, expr)
     tree type, expr;
{
  register tree value = expr;
  tree otype;

  if (type == error_mark_node || expr == error_mark_node)
    return error_mark_node;

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

  if (TREE_CODE (value) == OFFSET_REF)
    value = resolve_offset_ref (value);

  if (TREE_CODE (type) == ARRAY_TYPE)
    {
      /* Allow casting from T1* to T2[] because Cfront allows it.
         NIHCL uses it. It is not valid ANSI C however, and hence, not
         valid ANSI C++.  */
      if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
        {
          if (pedantic)
            pedwarn ("ANSI C++ forbids casting to an array type");
          type = build_pointer_type (TREE_TYPE (type));
        }
      else
        {
          error ("ANSI C++ forbids casting to an array type");
          return error_mark_node;
        }
    }

  if (TREE_CODE (type) == FUNCTION_TYPE
      || TREE_CODE (type) == METHOD_TYPE)
    {
      cp_error ("casting to function type `%T'", type);
      return error_mark_node;
    }

  if (processing_template_decl)
    {
      tree t = build_min (CAST_EXPR, type,
                          min_tree_cons (NULL_TREE, value, NULL_TREE));
      return t;
    }

  if (TREE_CODE (type) == VOID_TYPE)
    {
      /* Conversion to void does not cause any of the normal function to
       * pointer, array to pointer and lvalue to rvalue decays.  */
      
      value = convert_to_void (value, /*implicit=*/NULL);
      return value;
    }
  /* Convert functions and arrays to pointers and
     convert references to their expanded types,
     but don't convert any other types.  If, however, we are
     casting to a class type, there's no reason to do this: the
     cast will only succeed if there is a converting constructor,
     and the default conversions will be done at that point.  In
     fact, doing the default conversion here is actually harmful
     in cases like this:

     typedef int A[2];
     struct S { S(const A&); };

     since we don't want the array-to-pointer conversion done.  */
  if (!IS_AGGR_TYPE (type))
    {
      if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE
          || (TREE_CODE (TREE_TYPE (value)) == METHOD_TYPE
              /* Don't do the default conversion on a ->* expression.  */
              && ! (TREE_CODE (type) == POINTER_TYPE
                    && bound_pmf_p (value)))
          || TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
          || TREE_CODE (TREE_TYPE (value)) == REFERENCE_TYPE)
        value = default_conversion (value);
    }
  else if (TREE_CODE (TREE_TYPE (value)) == REFERENCE_TYPE)
    /* However, even for class types, we still need to strip away
       the reference type, since the call to convert_force below
       does not expect the input expression to be of reference
       type.  */
    value = convert_from_reference (value);
        
  otype = TREE_TYPE (value);

  /* Optionally warn about potentially worrisome casts.  */

  if (warn_cast_qual
      && TREE_CODE (type) == POINTER_TYPE
      && TREE_CODE (otype) == POINTER_TYPE
      && !at_least_as_qualified_p (TREE_TYPE (type),
                                   TREE_TYPE (otype)))
    cp_warning ("cast discards qualifiers from pointer target type");

  /* Warn about possible alignment problems.  */
  if (STRICT_ALIGNMENT && warn_cast_align
      && TREE_CODE (type) == POINTER_TYPE
      && TREE_CODE (otype) == POINTER_TYPE
      && TREE_CODE (TREE_TYPE (otype)) != VOID_TYPE
      && TREE_CODE (TREE_TYPE (otype)) != FUNCTION_TYPE
      && TYPE_ALIGN (TREE_TYPE (type)) > TYPE_ALIGN (TREE_TYPE (otype)))
    warning ("cast increases required alignment of target type");

#if 0
  /* We should see about re-enabling these, they seem useful to
     me.  */
  if (TREE_CODE (type) == INTEGER_TYPE
      && TREE_CODE (otype) == POINTER_TYPE
      && TYPE_PRECISION (type) != TYPE_PRECISION (otype))
    warning ("cast from pointer to integer of different size");

  if (TREE_CODE (type) == POINTER_TYPE
      && TREE_CODE (otype) == INTEGER_TYPE
      && TYPE_PRECISION (type) != TYPE_PRECISION (otype)
      /* Don't warn about converting 0 to pointer,
         provided the 0 was explicit--not cast or made by folding.  */
      && !(TREE_CODE (value) == INTEGER_CST && integer_zerop (value)))
    warning ("cast to pointer from integer of different size");
#endif

  if (TREE_CODE (type) == REFERENCE_TYPE)
    value = (convert_from_reference
             (convert_to_reference (type, value, CONV_C_CAST,
                                    LOOKUP_COMPLAIN, NULL_TREE)));
  else
    {
      tree ovalue;

      if (TREE_READONLY_DECL_P (value))
        value = decl_constant_value (value);

      ovalue = value;
      value = convert_force (type, value, CONV_C_CAST);

      /* Ignore any integer overflow caused by the cast.  */
      if (TREE_CODE (value) == INTEGER_CST)
        {
          TREE_OVERFLOW (value) = TREE_OVERFLOW (ovalue);
          TREE_CONSTANT_OVERFLOW (value) = TREE_CONSTANT_OVERFLOW (ovalue);
        }
    }

    /* Always produce some operator for an explicit cast,
       so we can tell (for -pedantic) that the cast is no lvalue.  */
  if (TREE_CODE (type) != REFERENCE_TYPE && value == expr
      && real_lvalue_p (value))
    value = non_lvalue (value);

  return value;
}
\f
/* Build an assignment expression of lvalue LHS from value RHS.
   MODIFYCODE is the code for a binary operator that we use
   to combine the old value of LHS with RHS to get the new value.
   Or else MODIFYCODE is NOP_EXPR meaning do a simple assignment.

   C++: If MODIFYCODE is INIT_EXPR, then leave references unbashed.  */

tree
build_modify_expr (lhs, modifycode, rhs)
     tree lhs;
     enum tree_code modifycode;
     tree rhs;
{
  register tree result;
  tree newrhs = rhs;
  tree lhstype = TREE_TYPE (lhs);
  tree olhstype = lhstype;
  tree olhs = lhs;

  /* Avoid duplicate error messages from operands that had errors.  */
  if (lhs == error_mark_node || rhs == error_mark_node)
    return error_mark_node;

  /* Types that aren't fully specified cannot be used in assignments.  */
  lhs = require_complete_type (lhs);

  newrhs = rhs;

  /* Handle control structure constructs used as "lvalues".  */

  switch (TREE_CODE (lhs))
    {
      /* Handle --foo = 5; as these are valid constructs in C++ */
    case PREDECREMENT_EXPR:
    case PREINCREMENT_EXPR:
      if (TREE_SIDE_EFFECTS (TREE_OPERAND (lhs, 0)))
        lhs = build (TREE_CODE (lhs), TREE_TYPE (lhs),
                     stabilize_reference (TREE_OPERAND (lhs, 0)),
                     TREE_OPERAND (lhs, 1));
      return build (COMPOUND_EXPR, lhstype,
                    lhs,
                    build_modify_expr (TREE_OPERAND (lhs, 0),
                                       modifycode, rhs));

      /* Handle (a, b) used as an "lvalue".  */
    case COMPOUND_EXPR:
      newrhs = build_modify_expr (TREE_OPERAND (lhs, 1),
                                  modifycode, rhs);
      if (newrhs == error_mark_node)
        return error_mark_node;
      return build (COMPOUND_EXPR, lhstype,
                    TREE_OPERAND (lhs, 0), newrhs);

    case MODIFY_EXPR:
      newrhs = build_modify_expr (TREE_OPERAND (lhs, 0), modifycode, rhs);
      if (newrhs == error_mark_node)
        return error_mark_node;
      return build (COMPOUND_EXPR, lhstype, lhs, newrhs);

      /* Handle (a ? b : c) used as an "lvalue".  */
    case COND_EXPR:
      rhs = save_expr (rhs);
      {
        /* Produce (a ? (b = rhs) : (c = rhs))
           except that the RHS goes through a save-expr
           so the code to compute it is only emitted once.  */
        tree cond;

        /* Check this here to avoid odd errors when trying to convert
           a throw to the type of the COND_EXPR.  */
        if (!lvalue_or_else (lhs, "assignment"))
          return error_mark_node;

        cond = build_conditional_expr
          (TREE_OPERAND (lhs, 0),
           build_modify_expr (cp_convert (TREE_TYPE (lhs),
                                          TREE_OPERAND (lhs, 1)),
                              modifycode, rhs),
           build_modify_expr (cp_convert (TREE_TYPE (lhs),
                                          TREE_OPERAND (lhs, 2)),
                              modifycode, rhs));

        if (cond == error_mark_node)
          return cond;
        /* Make sure the code to compute the rhs comes out
           before the split.  */
        return build (COMPOUND_EXPR, TREE_TYPE (lhs),
                      /* Case to void to suppress warning
                         from warn_if_unused_value.  */
                      cp_convert (void_type_node, rhs), cond);
      }

    default:
      break;
    }

  if (TREE_CODE (lhs) == OFFSET_REF)
    {
      if (TREE_OPERAND (lhs, 0) == NULL_TREE)
        {
          /* Static class member?  */
          tree member = TREE_OPERAND (lhs, 1);
          if (TREE_CODE (member) == VAR_DECL)
            lhs = member;
          else
            {
              compiler_error ("invalid static class member");
              return error_mark_node;
            }
        }
      else
        lhs = resolve_offset_ref (lhs);

      olhstype = lhstype = TREE_TYPE (lhs);
    }

  if (lhs == error_mark_node)
    return lhs;

  if (TREE_CODE (lhstype) == REFERENCE_TYPE
      && modifycode != INIT_EXPR)
    {
      lhs = convert_from_reference (lhs);
      olhstype = lhstype = TREE_TYPE (lhs);
    }

  /* If a binary op has been requested, combine the old LHS value with the RHS
     producing the value we should actually store into the LHS.  */

  if (modifycode == INIT_EXPR)
    {
      if (! IS_AGGR_TYPE (lhstype))
        /* Do the default thing */;
      else
        {
          result = build_method_call (lhs, ctor_identifier,
                                      build_expr_list (NULL_TREE, rhs),
                                      TYPE_BINFO (lhstype), LOOKUP_NORMAL);
          if (result == NULL_TREE)
            return error_mark_node;
          return result;
        }
    }
  else if (modifycode == NOP_EXPR)
    {
      /* `operator=' is not an inheritable operator.  */
      if (! IS_AGGR_TYPE (lhstype))
        /* Do the default thing */;
      else
        {
          result = build_opfncall (MODIFY_EXPR, LOOKUP_NORMAL,
                                   lhs, rhs, make_node (NOP_EXPR));
          if (result == NULL_TREE)
            return error_mark_node;
          return result;
        }
      lhstype = olhstype;
    }
  else if (PROMOTES_TO_AGGR_TYPE (lhstype, REFERENCE_TYPE))
    {
      my_friendly_abort (978652);
    }
  else
    {
      lhs = stabilize_reference (lhs);
      newrhs = build_binary_op (modifycode, lhs, rhs);
      if (newrhs == error_mark_node)
        {
          cp_error ("  in evaluation of `%Q(%#T, %#T)'", modifycode,
                    TREE_TYPE (lhs), TREE_TYPE (rhs));
          return error_mark_node;
        }
    }

  /* Handle a cast used as an "lvalue".
     We have already performed any binary operator using the value as cast.
     Now convert the result to the cast type of the lhs,
     and then true type of the lhs and store it there;
     then convert result back to the cast type to be the value
     of the assignment.  */

  switch (TREE_CODE (lhs))
    {
    case NOP_EXPR:
    case CONVERT_EXPR:
    case FLOAT_EXPR:
    case FIX_TRUNC_EXPR:
    case FIX_FLOOR_EXPR:
    case FIX_ROUND_EXPR:
    case FIX_CEIL_EXPR:
      if (TREE_CODE (TREE_TYPE (newrhs)) == ARRAY_TYPE
          || TREE_CODE (TREE_TYPE (newrhs)) == FUNCTION_TYPE
          || TREE_CODE (TREE_TYPE (newrhs)) == METHOD_TYPE
          || TREE_CODE (TREE_TYPE (newrhs)) == OFFSET_TYPE)
        newrhs = default_conversion (newrhs);
      {
        tree inner_lhs = TREE_OPERAND (lhs, 0);
        tree result;

        /* WP 5.4.1:  The result is an lvalue if T is a reference type,
           otherwise the result is an rvalue.   */
        if (! lvalue_p (lhs))
          pedwarn ("ANSI C++ forbids cast to non-reference type used as lvalue");

        result = build_modify_expr (inner_lhs, NOP_EXPR,
                                    cp_convert (TREE_TYPE (inner_lhs),
                                                cp_convert (lhstype, newrhs)));
        if (result == error_mark_node)
          return result;
        return cp_convert (TREE_TYPE (lhs), result);
      }

    default:
      break;
    }

  /* Now we have handled acceptable kinds of LHS that are not truly lvalues.
     Reject anything strange now.  */

  if (!lvalue_or_else (lhs, "assignment"))
    return error_mark_node;

  GNU_xref_assign (lhs);

  /* Warn about storing in something that is `const'.  */
  /* For C++, don't warn if this is initialization.  */
  if (modifycode != INIT_EXPR
      && (TREE_READONLY (lhs) || CP_TYPE_CONST_P (lhstype)
          /* Functions are not modifiable, even though they are
             lvalues.  */
          || TREE_CODE (TREE_TYPE (lhs)) == FUNCTION_TYPE
          || (IS_AGGR_TYPE_CODE (TREE_CODE (lhstype))
              && C_TYPE_FIELDS_READONLY (lhstype))
          || (TREE_CODE (lhstype) == REFERENCE_TYPE
              && CP_TYPE_CONST_P (TREE_TYPE (lhstype)))))
    readonly_error (lhs, "assignment", 0);

  /* If storing into a structure or union member,
     it has probably been given type `int'.
     Compute the type that would go with
     the actual amount of storage the member occupies.  */

  if (TREE_CODE (lhs) == COMPONENT_REF
      && (TREE_CODE (lhstype) == INTEGER_TYPE
          || TREE_CODE (lhstype) == REAL_TYPE
          || TREE_CODE (lhstype) == ENUMERAL_TYPE))
    {
      lhstype = TREE_TYPE (get_unwidened (lhs, 0));

      /* If storing in a field that is in actuality a short or narrower
         than one, we must store in the field in its actual type.  */

      if (lhstype != TREE_TYPE (lhs))
        {
          lhs = copy_node (lhs);
          TREE_TYPE (lhs) = lhstype;
        }
    }

  if (modifycode != INIT_EXPR)
    {
      /* Make modifycode now either a NOP_EXPR or an INIT_EXPR.  */
      modifycode = NOP_EXPR;
      /* Reference-bashing */
      if (TREE_CODE (lhstype) == REFERENCE_TYPE)
        {
          tree tmp = convert_from_reference (lhs);
          lhstype = TREE_TYPE (tmp);
          if (TYPE_SIZE (lhstype) == 0)
            {
              incomplete_type_error (lhs, lhstype);
              return error_mark_node;
            }
          lhs = tmp;
          olhstype = lhstype;
        }
      if (TREE_CODE (TREE_TYPE (newrhs)) == REFERENCE_TYPE)
        {
          tree tmp = convert_from_reference (newrhs);
          if (TYPE_SIZE (TREE_TYPE (tmp)) == 0)
            {
              incomplete_type_error (newrhs, TREE_TYPE (tmp));
              return error_mark_node;
            }
          newrhs = tmp;
        }
    }

  if (TREE_SIDE_EFFECTS (lhs))
    lhs = stabilize_reference (lhs);
  if (TREE_SIDE_EFFECTS (newrhs))
    newrhs = stabilize_reference (newrhs);

  /* Convert new value to destination type.  */

  if (TREE_CODE (lhstype) == ARRAY_TYPE)
    {
      int from_array;
      
      if (!same_or_base_type_p (lhstype, TREE_TYPE (rhs)))
        {
          cp_error ("incompatible types in assignment of `%T' to `%T'",
                    TREE_TYPE (rhs), lhstype);
          return error_mark_node;
        }

      /* Allow array assignment in compiler-generated code.  */
      if (pedantic && ! DECL_ARTIFICIAL (current_function_decl))
        pedwarn ("ANSI C++ forbids assignment of arrays");

      from_array = TREE_CODE (TREE_TYPE (newrhs)) == ARRAY_TYPE
                   ? 1 + (modifycode != INIT_EXPR): 0;
      return (build_vec_init
              (lhs, lhs, array_type_nelts (lhstype), newrhs,
               from_array));
    }

  if (modifycode == INIT_EXPR)
    {
      newrhs = convert_for_initialization (lhs, lhstype, newrhs, LOOKUP_NORMAL,
                                           "assignment", NULL_TREE, 0);
      if (current_function_decl && 
          lhs == DECL_RESULT (current_function_decl))
        {
          if (DECL_INITIAL (lhs))
            warning ("return value from function receives multiple initializations");
          DECL_INITIAL (lhs) = newrhs;
        }
    }
  else
    {
      /* Avoid warnings on enum bit fields.  */
      if (TREE_CODE (olhstype) == ENUMERAL_TYPE
          && TREE_CODE (lhstype) == INTEGER_TYPE)
        {
          newrhs = convert_for_assignment (olhstype, newrhs, "assignment",
                                           NULL_TREE, 0);
          newrhs = convert_force (lhstype, newrhs, 0);
        }
      else
        newrhs = convert_for_assignment (lhstype, newrhs, "assignment",
                                         NULL_TREE, 0);
      if (TREE_CODE (newrhs) == CALL_EXPR
          && TYPE_NEEDS_CONSTRUCTING (lhstype))
        newrhs = build_cplus_new (lhstype, newrhs);

      /* Can't initialize directly from a TARGET_EXPR, since that would
         cause the lhs to be constructed twice, and possibly result in
         accidental self-initialization.  So we force the TARGET_EXPR to be
         expanded without a target.  */
      if (TREE_CODE (newrhs) == TARGET_EXPR)
        newrhs = build (COMPOUND_EXPR, TREE_TYPE (newrhs), newrhs,
                        TREE_OPERAND (newrhs, 0));
    }

  if (newrhs == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (newrhs) == COND_EXPR)
    {
      tree lhs1;
      tree cond = TREE_OPERAND (newrhs, 0);

      if (TREE_SIDE_EFFECTS (lhs))
        cond = build_compound_expr (tree_cons
                                    (NULL_TREE, lhs,
                                     build_expr_list (NULL_TREE, cond)));

      /* Cannot have two identical lhs on this one tree (result) as preexpand
         calls will rip them out and fill in RTL for them, but when the
         rtl is generated, the calls will only be in the first side of the
         condition, not on both, or before the conditional jump! (mrs) */
      lhs1 = break_out_calls (lhs);

      if (lhs == lhs1)
        /* If there's no change, the COND_EXPR behaves like any other rhs.  */
        result = build (modifycode == NOP_EXPR ? MODIFY_EXPR : INIT_EXPR,
                        lhstype, lhs, newrhs);
      else
        {
          tree result_type = TREE_TYPE (newrhs);
          /* We have to convert each arm to the proper type because the
             types may have been munged by constant folding.  */
          result
            = build (COND_EXPR, result_type, cond,
                     build_modify_expr (lhs, modifycode,
                                        cp_convert (result_type,
                                                    TREE_OPERAND (newrhs, 1))),
                     build_modify_expr (lhs1, modifycode,
                                        cp_convert (result_type,
                                                    TREE_OPERAND (newrhs, 2))));
        }
    }
  else
    result = build (modifycode == NOP_EXPR ? MODIFY_EXPR : INIT_EXPR,
                    lhstype, lhs, newrhs);

  TREE_SIDE_EFFECTS (result) = 1;

  /* If we got the LHS in a different type for storing in,
     convert the result back to the nominal type of LHS
     so that the value we return always has the same type
     as the LHS argument.  */

  if (olhstype == TREE_TYPE (result))
    return result;
  /* Avoid warnings converting integral types back into enums
     for enum bit fields.  */
  if (TREE_CODE (TREE_TYPE (result)) == INTEGER_TYPE
      && TREE_CODE (olhstype) == ENUMERAL_TYPE)
    {
      result = build (COMPOUND_EXPR, olhstype, result, olhs);
      TREE_NO_UNUSED_WARNING (result) = 1;
      return result;
    }
  return convert_for_assignment (olhstype, result, "assignment",
                                 NULL_TREE, 0);
}

tree
build_x_modify_expr (lhs, modifycode, rhs)
     tree lhs;
     enum tree_code modifycode;
     tree rhs;
{
  if (processing_template_decl)
    return build_min_nt (MODOP_EXPR, lhs,
                         build_min_nt (modifycode, NULL_TREE, NULL_TREE), rhs);

  if (modifycode != NOP_EXPR)
    {
      tree rval = build_opfncall (MODIFY_EXPR, LOOKUP_NORMAL, lhs, rhs,
                                  make_node (modifycode));
      if (rval)
        return rval;
    }
  return build_modify_expr (lhs, modifycode, rhs);
}

\f
/* Get difference in deltas for different pointer to member function
   types.  Return integer_zero_node, if FROM cannot be converted to a
   TO type.  If FORCE is true, then allow reverse conversions as well.

   Note that the naming of FROM and TO is kind of backwards; the return
   value is what we add to a TO in order to get a FROM.  They are named
   this way because we call this function to find out how to convert from
   a pointer to member of FROM to a pointer to member of TO.  */

static tree
get_delta_difference (from, to, force)
     tree from, to;
     int force;
{
  tree delta = integer_zero_node;
  tree binfo;
  
  if (to == from)
    return delta;

  /* Should get_base_distance here, so we can check if any thing along the
     path is virtual, and we need to make sure we stay
     inside the real binfos when going through virtual bases.
     Maybe we should replace virtual bases with
     binfo_member (...CLASSTYPE_VBASECLASSES...)...  (mrs) */
  binfo = get_binfo (from, to, 1);
  if (binfo == error_mark_node)
    {
      error ("   in pointer to member function conversion");
      return delta;
    }
  if (binfo == 0)
    {
      if (!force)
        {
          error_not_base_type (from, to);
          error ("   in pointer to member conversion");
          return delta;
        }
      binfo = get_binfo (to, from, 1);
      if (binfo == 0 || binfo == error_mark_node)
        return delta;
      if (binfo_from_vbase (binfo))
        {
          binfo = binfo_member (BINFO_TYPE (binfo),
                                CLASSTYPE_VBASECLASSES (from));
          cp_warning ("pointer to member cast to virtual base `%T'",
                      BINFO_TYPE (binfo));
          warning ("  will only work if you are very careful");
        }
      delta = BINFO_OFFSET (binfo);
      delta = cp_convert (ptrdiff_type_node, delta);
      
      return build_binary_op (MINUS_EXPR,
                              integer_zero_node,
                              delta);
    }

  if (binfo_from_vbase (binfo))
    {
      if (force)
        {
          cp_warning ("pointer to member cast from virtual base `%T'",
                      BINFO_TYPE (binfo));
          warning ("  will only work if you are very careful");
        }
      else
        cp_error ("pointer to member conversion from virtual base `%T'",
                  BINFO_TYPE (binfo));
    }

  return BINFO_OFFSET (binfo);
}

tree
build_ptrmemfunc1 (type, delta, idx, pfn, delta2)
     tree type, delta, idx, pfn, delta2;
{
  tree u;

#if 0
  /* This is the old way we did it.  We want to avoid calling
     digest_init, so that it can give an error if we use { } when
     initializing a pointer to member function.  */

  if (pfn)
    {
      u = build_nt (CONSTRUCTOR, NULL_TREE,
                    tree_cons (pfn_identifier, pfn, NULL_TREE));
    }
  else
    {
      u = build_nt (CONSTRUCTOR, NULL_TREE,
                    tree_cons (delta2_identifier, delta2, NULL_TREE));
    }

  u = build_nt (CONSTRUCTOR, NULL_TREE,
                tree_cons (NULL_TREE, delta,
                           tree_cons (NULL_TREE, idx,
                                      tree_cons (NULL_TREE, u, NULL_TREE))));

  return digest_init (type, u, (tree*)0);
#else
  tree delta_field, idx_field, pfn_or_delta2_field, pfn_field, delta2_field;
  tree subtype;
  int allconstant, allsimple;

  delta_field = TYPE_FIELDS (type);
  idx_field = TREE_CHAIN (delta_field);
  pfn_or_delta2_field = TREE_CHAIN (idx_field);
  subtype = TREE_TYPE (pfn_or_delta2_field);
  pfn_field = TYPE_FIELDS (subtype);
  delta2_field = TREE_CHAIN (pfn_field);

  if (pfn)
    {
      allconstant = TREE_CONSTANT (pfn);
      allsimple = !! initializer_constant_valid_p (pfn, TREE_TYPE (pfn));
      u = tree_cons (pfn_field, pfn, NULL_TREE);
    }
  else
    {
      delta2 = convert_and_check (delta_type_node, delta2);
      allconstant = TREE_CONSTANT (delta2);
      allsimple = !! initializer_constant_valid_p (delta2, TREE_TYPE (delta2));
      u = tree_cons (delta2_field, delta2, NULL_TREE);
    }

  delta = convert_and_check (delta_type_node, delta);
  idx = convert_and_check (delta_type_node, idx);

  allconstant = allconstant && TREE_CONSTANT (delta) && TREE_CONSTANT (idx);
  allsimple = allsimple
    && initializer_constant_valid_p (delta, TREE_TYPE (delta))
      && initializer_constant_valid_p (idx, TREE_TYPE (idx));

  u = build (CONSTRUCTOR, subtype, NULL_TREE, u);
  u = tree_cons (delta_field, delta,
                 tree_cons (idx_field, idx,
                            tree_cons (pfn_or_delta2_field, u, NULL_TREE)));
  u = build (CONSTRUCTOR, type, NULL_TREE, u);
  TREE_CONSTANT (u) = allconstant;
  TREE_STATIC (u) = allconstant && allsimple;
  return u;
#endif
}

/* Build a constructor for a pointer to member function.  It can be
   used to initialize global variables, local variable, or used
   as a value in expressions.  TYPE is the POINTER to METHOD_TYPE we
   want to be.

   If FORCE is non-zero, then force this conversion, even if
   we would rather not do it.  Usually set when using an explicit
   cast.

   Return error_mark_node, if something goes wrong.  */

tree
build_ptrmemfunc (type, pfn, force)
     tree type, pfn;
     int force;
{
  tree fn;
  tree pfn_type = TREE_TYPE (pfn);
  tree to_type = build_ptrmemfunc_type (type);

  /* Handle multiple conversions of pointer to member functions.  */
  if (TYPE_PTRMEMFUNC_P (TREE_TYPE (pfn)))
    {
      tree idx = integer_zero_node;
      tree delta = integer_zero_node;
      tree delta2 = integer_zero_node;
      tree npfn = NULL_TREE;
      tree ndelta, ndelta2;
      tree e1, e2, e3, n;

      if (!force 
          && !can_convert_arg (to_type, TREE_TYPE (pfn), pfn))
        cp_error ("conversion to `%T' from `%T'", 
                  to_type, pfn_type);

      if (TREE_CODE (pfn) == PTRMEM_CST)
        {
          /* We could just build the resulting CONSTRUCTOR now, but we
             don't, relying on the general machinery below, together
             with constant-folding, to do the right thing.  We don't
             want to return a PTRMEM_CST here, since a
             pointer-to-member constant is no longer a valid template
             argument once it is cast to any type, including its
             original type.  */
          expand_ptrmemfunc_cst (pfn, &ndelta, &idx, &npfn, &ndelta2);
          if (npfn)
            /* This constant points to a non-virtual function.
               NDELTA2 will be NULL, but it's value doesn't really
               matter since we won't use it anyhow.  */
            ndelta2 = integer_zero_node;
        }
      else if (same_type_p (to_type, pfn_type))
        /* We don't have to do any conversion.  Note that we do this
           after checking for a PTRMEM_CST so that a PTRMEM_CST, cast
           to its own type, will not be considered a legal non-type
           template argument.  */
        return pfn;
      else
        {
          ndelta = cp_convert (ptrdiff_type_node, 
                               build_component_ref (pfn, 
                                                    delta_identifier, 
                                                    NULL_TREE, 0));
          ndelta2 = cp_convert (ptrdiff_type_node, 
                                DELTA2_FROM_PTRMEMFUNC (pfn));
          idx = build_component_ref (pfn, index_identifier, NULL_TREE, 0);
        }

      n = get_delta_difference (TYPE_PTRMEMFUNC_OBJECT_TYPE (pfn_type),
                                TYPE_PTRMEMFUNC_OBJECT_TYPE (to_type),
                                force);
      delta = build_binary_op (PLUS_EXPR, ndelta, n);
      delta2 = build_binary_op (PLUS_EXPR, ndelta2, n);
      e1 = fold (build (GT_EXPR, boolean_type_node, idx, integer_zero_node));
          
      /* If it's a virtual function, this is what we want.  */
      e2 = build_ptrmemfunc1 (to_type, delta, idx,
                              NULL_TREE, delta2);

      pfn = PFN_FROM_PTRMEMFUNC (pfn);
      npfn = build1 (NOP_EXPR, type, pfn);
      TREE_CONSTANT (npfn) = TREE_CONSTANT (pfn);

      /* But if it's a non-virtual function, or NULL, we use this
         instead.  */
      e3 = build_ptrmemfunc1 (to_type, delta,
                              idx, npfn, NULL_TREE);
      return build_conditional_expr (e1, e2, e3);
    }

  /* Handle null pointer to member function conversions.  */
  if (integer_zerop (pfn))
    {
      pfn = build_c_cast (type, integer_zero_node);
      return build_ptrmemfunc1 (to_type,
                                integer_zero_node, integer_zero_node,
                                pfn, NULL_TREE);
    }

  if (type_unknown_p (pfn))
    return instantiate_type (type, pfn, 1);

  fn = TREE_OPERAND (pfn, 0);
  my_friendly_assert (TREE_CODE (fn) == FUNCTION_DECL, 0);
  return make_ptrmem_cst (to_type, fn);
}

/* Return the DELTA, IDX, PFN, and DELTA2 values for the PTRMEM_CST
   given by CST.  */

void
expand_ptrmemfunc_cst (cst, delta, idx, pfn, delta2)
     tree cst;
     tree *delta;
     tree *idx;
     tree *pfn;
     tree *delta2;
{
  tree type = TREE_TYPE (cst);
  tree fn = PTRMEM_CST_MEMBER (cst);
  tree ptr_class, fn_class;

  my_friendly_assert (TREE_CODE (fn) == FUNCTION_DECL, 0);

  /* The class that the function belongs to.  */
  fn_class = DECL_CLASS_CONTEXT (fn);

  /* The class that we're creating a pointer to member of.  */
  ptr_class = TYPE_PTRMEMFUNC_OBJECT_TYPE (type);

  /* First, calculate the adjustment to the function's class.  */
  *delta = get_delta_difference (fn_class, ptr_class, /*force=*/0);

  if (!DECL_VIRTUAL_P (fn))
    {
      *idx = size_binop (MINUS_EXPR, integer_zero_node, integer_one_node);
      *pfn = convert (TYPE_PTRMEMFUNC_FN_TYPE (type), build_addr_func (fn));
      *delta2 = NULL_TREE;
    }
  else
    {
      /* If we're dealing with a virtual function, we have to adjust 'this'
         again, to point to the base which provides the vtable entry for
         fn; the call will do the opposite adjustment.  */
      tree orig_class = DECL_VIRTUAL_CONTEXT (fn);
      tree binfo = binfo_or_else (orig_class, fn_class);
      *delta = size_binop (PLUS_EXPR, *delta, BINFO_OFFSET (binfo));

      /* Map everything down one to make room for the null PMF.  */
      *idx = size_binop (PLUS_EXPR, DECL_VINDEX (fn), integer_one_node);
      *pfn = NULL_TREE;

      /* Offset from an object of PTR_CLASS to the vptr for ORIG_CLASS.  */
      *delta2 = size_binop (PLUS_EXPR, *delta,
                            get_vfield_offset (TYPE_BINFO (orig_class)));
    }
}

/* Return an expression for DELTA2 from the pointer-to-member function
   given by T.  */

tree
delta2_from_ptrmemfunc (t)
     tree t;
{
  if (TREE_CODE (t) == PTRMEM_CST)
    {
      tree delta;
      tree idx;
      tree pfn;
      tree delta2;
      
      expand_ptrmemfunc_cst (t, &delta, &idx, &pfn, &delta2);
      if (delta2)
        return delta2;
    }

  return (build_component_ref 
          (build_component_ref (t,
                                pfn_or_delta2_identifier, NULL_TREE,
                                0), 
           delta2_identifier, NULL_TREE, 0)); 
}

/* Return an expression for PFN from the pointer-to-member function
   given by T.  */

tree
pfn_from_ptrmemfunc (t)
     tree t;
{
  if (TREE_CODE (t) == PTRMEM_CST)
    {
      tree delta;
      tree idx;
      tree pfn;
      tree delta2;
      
      expand_ptrmemfunc_cst (t, &delta, &idx, &pfn, &delta2);
      if (pfn)
        return pfn;
    }

  return (build_component_ref 
          (build_component_ref (t,
                                pfn_or_delta2_identifier, NULL_TREE,
                                0), 
           pfn_identifier, NULL_TREE, 0)); 
}

/* Convert value RHS to type TYPE as preparation for an assignment to
   an lvalue of type TYPE.  ERRTYPE is a string to use in error
   messages: "assignment", "return", etc.  If FNDECL is non-NULL, we
   are doing the conversion in order to pass the PARMNUMth argument of
   FNDECL.  */

static tree
convert_for_assignment (type, rhs, errtype, fndecl, parmnum)
     tree type, rhs;
     const char *errtype;
     tree fndecl;
     int parmnum;
{
  register enum tree_code codel = TREE_CODE (type);
  register tree rhstype;
  register enum tree_code coder;

  if (codel == OFFSET_TYPE)
    my_friendly_abort (990505);

  if (TREE_CODE (rhs) == OFFSET_REF)
    rhs = resolve_offset_ref (rhs);

  /* Strip NON_LVALUE_EXPRs since we aren't using as an lvalue.  */
  if (TREE_CODE (rhs) == NON_LVALUE_EXPR)
    rhs = TREE_OPERAND (rhs, 0);

  rhstype = TREE_TYPE (rhs);
  coder = TREE_CODE (rhstype);

  if (rhs == error_mark_node || rhstype == error_mark_node)
    return error_mark_node;
  if (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node)
    return error_mark_node;

  /* Issue warnings about peculiar, but legal, uses of NULL.  */
  if (ARITHMETIC_TYPE_P (type) && rhs == null_node)
    cp_warning ("converting NULL to non-pointer type");

  /* The RHS of an assignment cannot have void type.  */
  if (coder == VOID_TYPE)
    {
      error ("void value not ignored as it ought to be");
      return error_mark_node;
    }

  /* Simplify the RHS if possible.  */
  if (TREE_CODE (rhs) == CONST_DECL)
    rhs = DECL_INITIAL (rhs);
  else if (TREE_READONLY_DECL_P (rhs))
    rhs = decl_constant_value (rhs);

  /* Warn about assigning a floating-point type to an integer type.  */
  if (coder == REAL_TYPE && codel == INTEGER_TYPE)
    {
      if (fndecl)
        cp_warning ("`%T' used for argument %P of `%D'",
                    rhstype, parmnum, fndecl);
      else
        cp_warning ("%s to `%T' from `%T'", errtype, type, rhstype);
    }
  /* And warn about assigning a negative value to an unsigned
     variable.  */
  else if (TREE_UNSIGNED (type) && codel != BOOLEAN_TYPE)
    {
      if (TREE_CODE (rhs) == INTEGER_CST
          && TREE_NEGATED_INT (rhs))
        {
          if (fndecl)
            cp_warning ("negative value `%E' passed as argument %P of `%D'",
                        rhs, parmnum, fndecl);
          else
            cp_warning ("%s of negative value `%E' to `%T'",
                        errtype, rhs, type);
        }
      overflow_warning (rhs);
      if (TREE_CONSTANT (rhs))
        rhs = fold (rhs);
    }

  /* [expr.ass]

     The expression is implicitly converted (clause _conv_) to the
     cv-unqualified type of the left operand.  */
  if (!can_convert_arg (type, rhstype, rhs))
    {
      /* When -Wno-pmf-conversions is use, we just silently allow
         conversions from pointers-to-members to plain pointers.  If
         the conversion doesn't work, cp_convert will complain.  */
      if (!warn_pmf2ptr 
          && TYPE_PTR_P (type) 
          && TYPE_PTRMEMFUNC_P (rhstype))
        rhs = cp_convert (strip_top_quals (type), rhs);
      else 
        {
          /* If the right-hand side has unknown type, then it is an
             overloaded function.  Call instantiate_type to get error
             messages.  */
          if (rhstype == unknown_type_node)
            instantiate_type (type, rhs, 1);
          else if (fndecl)
            cp_error ("cannot convert `%T' to `%T' for argument `%P' to `%D'",
                      rhstype, type, parmnum, fndecl);
          else
            cp_error ("cannot convert `%T' to `%T' in %s", rhstype, type, 
                      errtype);
          return error_mark_node;
        }
    }
  return perform_implicit_conversion (strip_top_quals (type), rhs);
}

/* Convert RHS to be of type TYPE.
   If EXP is non-zero, it is the target of the initialization.
   ERRTYPE is a string to use in error messages.

   Two major differences between the behavior of
   `convert_for_assignment' and `convert_for_initialization'
   are that references are bashed in the former, while
   copied in the latter, and aggregates are assigned in
   the former (operator=) while initialized in the
   latter (X(X&)).

   If using constructor make sure no conversion operator exists, if one does
   exist, an ambiguity exists.

   If flags doesn't include LOOKUP_COMPLAIN, don't complain about anything.  */

tree
convert_for_initialization (exp, type, rhs, flags, errtype, fndecl, parmnum)
     tree exp, type, rhs;
     int flags;
     const char *errtype;
     tree fndecl;
     int parmnum;
{
  register enum tree_code codel = TREE_CODE (type);
  register tree rhstype;
  register enum tree_code coder;

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

  if (rhs == error_mark_node
      || (TREE_CODE (rhs) == TREE_LIST && TREE_VALUE (rhs) == error_mark_node))
    return error_mark_node;

  if (TREE_CODE (rhs) == OFFSET_REF)
    {
      rhs = resolve_offset_ref (rhs);
      if (rhs == error_mark_node)
        return error_mark_node;
    }

  if (TREE_CODE (TREE_TYPE (rhs)) == REFERENCE_TYPE)
    rhs = convert_from_reference (rhs);

  if ((TREE_CODE (TREE_TYPE (rhs)) == ARRAY_TYPE
       && TREE_CODE (type) != ARRAY_TYPE
       && (TREE_CODE (type) != REFERENCE_TYPE
           || TREE_CODE (TREE_TYPE (type)) != ARRAY_TYPE))
      || (TREE_CODE (TREE_TYPE (rhs)) == FUNCTION_TYPE
          && (TREE_CODE (type) != REFERENCE_TYPE
              || TREE_CODE (TREE_TYPE (type)) != FUNCTION_TYPE))
      || TREE_CODE (TREE_TYPE (rhs)) == METHOD_TYPE)
    rhs = default_conversion (rhs);

  rhstype = TREE_TYPE (rhs);
  coder = TREE_CODE (rhstype);

  if (coder == ERROR_MARK)
    return error_mark_node;

  /* We accept references to incomplete types, so we can
     return here before checking if RHS is of complete type.  */
     
  if (codel == REFERENCE_TYPE)
    {
      /* This should eventually happen in convert_arguments.  */
      extern int warningcount, errorcount;
      int savew = 0, savee = 0;

      if (fndecl)
        savew = warningcount, savee = errorcount;
      rhs = initialize_reference (type, rhs);
      if (fndecl)
        {
          if (warningcount > savew)
            cp_warning_at ("in passing argument %P of `%+D'", parmnum, fndecl);
          else if (errorcount > savee)
            cp_error_at ("in passing argument %P of `%+D'", parmnum, fndecl);
        }
      return rhs;
    }      

  if (exp != 0)
    exp = require_complete_type (exp);
  if (exp == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (rhstype) == REFERENCE_TYPE)
    rhstype = TREE_TYPE (rhstype);

  type = complete_type (type);

  if (IS_AGGR_TYPE (type))
    return ocp_convert (type, rhs, CONV_IMPLICIT|CONV_FORCE_TEMP, flags);

  if (type == TREE_TYPE (rhs))
    {
      /* Issue warnings about peculiar, but legal, uses of NULL.  We
         do this *before* the call to decl_constant_value so as to
         avoid duplicate warnings on code like `const int I = NULL;
         f(I);'.  */
      if (ARITHMETIC_TYPE_P (type) && rhs == null_node)
        cp_warning ("converting NULL to non-pointer type");

      if (TREE_READONLY_DECL_P (rhs))
        rhs = decl_constant_value (rhs);

      return rhs;
    }

  return convert_for_assignment (type, rhs, errtype, fndecl, parmnum);
}
\f
/* Expand an ASM statement with operands, handling output operands
   that are not variables or INDIRECT_REFS by transforming such
   cases into cases that expand_asm_operands can handle.

   Arguments are same as for expand_asm_operands.

   We don't do default conversions on all inputs, because it can screw
   up operands that are expected to be in memory.  */

void
c_expand_asm_operands (string, outputs, inputs, clobbers, vol, filename, line)
     tree string, outputs, inputs, clobbers;
     int vol;
     char *filename;
     int line;
{
  int noutputs = list_length (outputs);
  register int i;
  /* o[I] is the place that output number I should be written.  */
  register tree *o = (tree *) alloca (noutputs * sizeof (tree));
  register tree tail;

  /* Record the contents of OUTPUTS before it is modified.  */
  for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
    o[i] = TREE_VALUE (tail);

  /* Generate the ASM_OPERANDS insn;
     store into the TREE_VALUEs of OUTPUTS some trees for
     where the values were actually stored.  */
  expand_asm_operands (string, outputs, inputs, clobbers, vol, filename, line);

  /* Copy all the intermediate outputs into the specified outputs.  */
  for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
    {
      if (o[i] != TREE_VALUE (tail))
        {
          expand_expr (build_modify_expr (o[i], NOP_EXPR, TREE_VALUE (tail)),
                       const0_rtx, VOIDmode, EXPAND_NORMAL);
          free_temp_slots ();
        }
      /* Detect modification of read-only values.
         (Otherwise done by build_modify_expr.)  */
      else
        {
          tree type = TREE_TYPE (o[i]);
          if (CP_TYPE_CONST_P (type)
              || (IS_AGGR_TYPE_CODE (TREE_CODE (type))
                  && C_TYPE_FIELDS_READONLY (type)))
            readonly_error (o[i], "modification by `asm'", 1);
        }
    }

  /* Those MODIFY_EXPRs could do autoincrements.  */
  emit_queue ();
}
\f
/* If RETVAL is the address of, or a reference to, a local variable or
   temporary give an appropraite warning.  */

static void
maybe_warn_about_returning_address_of_local (retval)
     tree retval;
{
  tree valtype = TREE_TYPE (DECL_RESULT (current_function_decl));

  if (TREE_CODE (valtype) == REFERENCE_TYPE)
    {
      tree whats_returned;

      /* Sort through common things to see what it is
         we are returning.  */
      whats_returned = retval;
      if (TREE_CODE (whats_returned) == COMPOUND_EXPR)
        {
          whats_returned = TREE_OPERAND (whats_returned, 1);
          if (TREE_CODE (whats_returned) == ADDR_EXPR)
            whats_returned = TREE_OPERAND (whats_returned, 0);
        }
      while (TREE_CODE (whats_returned) == CONVERT_EXPR
             || TREE_CODE (whats_returned) == NOP_EXPR)
        whats_returned = TREE_OPERAND (whats_returned, 0);
      if (TREE_CODE (whats_returned) == ADDR_EXPR)
        {
          whats_returned = TREE_OPERAND (whats_returned, 0);
          while (TREE_CODE (whats_returned) == AGGR_INIT_EXPR
                 || TREE_CODE (whats_returned) == TARGET_EXPR)
            {
              /* Get the target.  */
              whats_returned = TREE_OPERAND (whats_returned, 0);
              warning ("returning reference to temporary");
            }
        }

      if (TREE_CODE (whats_returned) == VAR_DECL 
          && DECL_NAME (whats_returned))
        {
          if (TEMP_NAME_P (DECL_NAME (whats_returned)))
            warning ("reference to non-lvalue returned");
          else if (TREE_CODE (TREE_TYPE (whats_returned)) != REFERENCE_TYPE
                   && DECL_FUNCTION_SCOPE_P (whats_returned)
                   && !(TREE_STATIC (whats_returned)
                        || TREE_PUBLIC (whats_returned)))
            cp_warning_at ("reference to local variable `%D' returned", 
                           whats_returned);
        }
    }
  else if (TREE_CODE (retval) == ADDR_EXPR)
    {
      tree whats_returned = TREE_OPERAND (retval, 0);

      if (TREE_CODE (whats_returned) == VAR_DECL
          && DECL_NAME (whats_returned)
          && DECL_FUNCTION_SCOPE_P (whats_returned)
          && !(TREE_STATIC (whats_returned)
               || TREE_PUBLIC (whats_returned)))
        cp_warning_at ("address of local variable `%D' returned", 
                       whats_returned);
    }
}

/* Check that returning RETVAL from the current function is legal.
   Return an expression explicitly showing all conversions required to
   change RETVAL into the function return type, and to assign it to
   the DECL_RESULT for the function.  */

tree
check_return_expr (retval)
     tree retval;
{
  tree result;
  /* The type actually returned by the function, after any
     promotions.  */
  tree valtype;
  int fn_returns_value_p;

  /* A `volatile' function is one that isn't supposed to return, ever.
     (This is a G++ extension, used to get better code for functions
     that call the `volatile' function.)  */
  if (TREE_THIS_VOLATILE (current_function_decl))
    warning ("function declared `noreturn' has a `return' statement");

  /* Check for various simple errors.  */
  if (retval == error_mark_node)
    {
      /* If an error occurred, there's nothing to do.  */
      current_function_returns_null = 1;
      return error_mark_node;
    }
  else if (dtor_label)
    {
      if (retval)
        error ("returning a value from a destructor");
      return NULL_TREE;
    }
  else if (in_function_try_handler
           && DECL_CONSTRUCTOR_P (current_function_decl))
    {
      /* If a return statement appears in a handler of the
         function-try-block of a constructor, the program is ill-formed. */
      error ("cannot return from a handler of a function-try-block of a constructor");
      return error_mark_node;
    }
  else if (retval && DECL_CONSTRUCTOR_P (current_function_decl))
    /* You can't return a value from a constructor.  */
    error ("returning a value from a constructor");

  /* Constructors actually always return `this', even though in C++
     you can't return a value from a constructor.  */
  if (DECL_CONSTRUCTOR_P (current_function_decl))
    retval = current_class_ptr;

  /* When no explicit return-value is given in a function with a named
     return value, the named return value is used.  */
  result = DECL_RESULT (current_function_decl);
  valtype = TREE_TYPE (result);
  my_friendly_assert (valtype != NULL_TREE, 19990924);
  fn_returns_value_p = !same_type_p (valtype, void_type_node);
  if (!retval && DECL_NAME (result) && fn_returns_value_p)
    retval = result;

  /* Check for a return statement with no return value in a function
     that's supposed to return a value.  */
  if (!retval && fn_returns_value_p)
    {
      pedwarn ("`return' with no value, in function returning non-void");
      /* Clear this, so finish_function won't say that we reach the
         end of a non-void function (which we don't, we gave a
         return!).  */
      current_function_returns_null = 0;
    }
  /* Check for a return statement with a value in a function that
     isn't supposed to return a value.  */
  else if (retval && !fn_returns_value_p)
    {     
      if (same_type_p (TREE_TYPE (retval), void_type_node))
        /* You can return a `void' value from a function of `void'
           type.  In that case, we have to evaluate the expression for
           its side-effects.  */
          finish_expr_stmt (retval);
      else
        pedwarn ("`return' with a value, in function returning void");

      current_function_returns_null = 1;

      /* There's really no value to return, after all.  */
      return NULL_TREE;
    }
  else if (!retval)
    /* Remember that this function can sometimes return without a
       value.  */
    current_function_returns_null = 1;

  /* Only operator new(...) throw(), can return NULL [expr.new/13].  */
  if ((DECL_NAME (current_function_decl) == ansi_opname[(int) NEW_EXPR]
       || DECL_NAME (current_function_decl) == ansi_opname[(int) VEC_NEW_EXPR])
      && !TYPE_NOTHROW_P (TREE_TYPE (current_function_decl))
      && null_ptr_cst_p (retval))
    cp_warning ("operator new should throw an exception, not return NULL");

  /* Effective C++ rule 15.  See also start_function.  */
  if (warn_ecpp
      && DECL_NAME (current_function_decl) == ansi_opname[(int) MODIFY_EXPR]
      && retval != current_class_ref)
    cp_warning ("`operator=' should return a reference to `*this'");

  /* We don't need to do any conversions when there's nothing being
     returned.  */
  if (!retval)
    return NULL_TREE;

  /* Do any required conversions.  */
  if (retval == result || DECL_CONSTRUCTOR_P (current_function_decl))
    /* No conversions are required.  */
    ;
  else
    {
      /* The type the function is declared to return.  */
      tree functype = TREE_TYPE (TREE_TYPE (current_function_decl));

      /* First convert the value to the function's return type, then
         to the type of return value's location to handle the
         case that functype is thiner than the valtype. */
      retval = convert_for_initialization
        (NULL_TREE, functype, retval, LOOKUP_NORMAL|LOOKUP_ONLYCONVERTING,
         "return", NULL_TREE, 0);
      retval = convert (valtype, retval);

      /* If the conversion failed, treat this just like `return;'.  */
      if (retval == error_mark_node)
        return NULL_TREE;
      /* We can't initialize a register from a AGGR_INIT_EXPR.  */
      else if (! current_function_returns_struct
               && TREE_CODE (retval) == TARGET_EXPR
               && TREE_CODE (TREE_OPERAND (retval, 1)) == AGGR_INIT_EXPR)
        retval = build (COMPOUND_EXPR, TREE_TYPE (retval), retval,
                        TREE_OPERAND (retval, 0));
      else
        maybe_warn_about_returning_address_of_local (retval);
    }
  
  /* Actually copy the value returned into the appropriate location.  */
  if (retval && retval != result)
    retval = build (INIT_EXPR, TREE_TYPE (result), result, retval);

  /* All done.  Remember that this function did return a value.  */
  current_function_returns_value = 1;
  return retval;
}

/* Expand a C `return' statement.
   RETVAL is the expression for what to return,
   or a null pointer for `return;' with no value.

   C++: upon seeing a `return', we must call destructors on all
   variables in scope which had constructors called on them.
   This means that if in a destructor, the base class destructors
   must be called before returning.

   The RETURN statement in C++ has initialization semantics.  */

void
c_expand_return (retval)
     tree retval;
{
  if (!retval)
    expand_null_return ();
  else
    {
      expand_start_target_temps ();
      expand_return (retval);
      expand_end_target_temps ();
    }
}
\f
/* Start a C switch statement, testing expression EXP.
   Return EXP if it is valid, an error node otherwise.  */

tree
c_expand_start_case (exp)
     tree exp;
{
  tree type, idx;

  exp = build_expr_type_conversion (WANT_INT | WANT_ENUM, exp, 1);
  if (exp == NULL_TREE)
    {
      error ("switch quantity not an integer");
      exp = error_mark_node;
    }
  if (exp == error_mark_node)
    return error_mark_node;

  exp = default_conversion (exp);
  type = TREE_TYPE (exp);
  idx = get_unwidened (exp, 0);
  /* We can't strip a conversion from a signed type to an unsigned,
     because if we did, int_fits_type_p would do the wrong thing
     when checking case values for being in range,
     and it's too hard to do the right thing.  */
  if (TREE_UNSIGNED (TREE_TYPE (exp)) == TREE_UNSIGNED (TREE_TYPE (idx)))
    exp = idx;

  expand_start_case
    (1, fold (build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp)),
     type, "switch statement");

  return exp;
}

/* Returns non-zero if the pointer-type FROM can be converted to the
   pointer-type TO via a qualification conversion.  If CONSTP is -1,
   then we return non-zero if the pointers are similar, and the
   cv-qualification signature of FROM is a proper subset of that of TO.

   If CONSTP is positive, then all outer pointers have been
   const-qualified.  */

static int
comp_ptr_ttypes_real (to, from, constp)
     tree to, from;
     int constp;
{
  int to_more_cv_qualified = 0;

  for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
    {
      if (TREE_CODE (to) != TREE_CODE (from))
        return 0;

      if (TREE_CODE (from) == OFFSET_TYPE
          && same_type_p (TYPE_OFFSET_BASETYPE (from),
                          TYPE_OFFSET_BASETYPE (to)))
          continue;

      /* Const and volatile mean something different for function types,
         so the usual checks are not appropriate.  */
      if (TREE_CODE (to) != FUNCTION_TYPE && TREE_CODE (to) != METHOD_TYPE)
        {
          if (!at_least_as_qualified_p (to, from))
            return 0;

          if (!at_least_as_qualified_p (from, to))
            {
              if (constp == 0)
                return 0;
              else
                ++to_more_cv_qualified;
            }

          if (constp > 0)
            constp &= TYPE_READONLY (to);
        }

      if (TREE_CODE (to) != POINTER_TYPE)
        return 
          same_type_p (TYPE_MAIN_VARIANT (to), TYPE_MAIN_VARIANT (from))
          && (constp >= 0 || to_more_cv_qualified);
    }
}

/* When comparing, say, char ** to char const **, this function takes the
   'char *' and 'char const *'.  Do not pass non-pointer types to this
   function.  */

int
comp_ptr_ttypes (to, from)
     tree to, from;
{
  return comp_ptr_ttypes_real (to, from, 1);
}

/* Returns 1 if to and from are (possibly multi-level) pointers to the same
   type or inheritance-related types, regardless of cv-quals.  */

int
ptr_reasonably_similar (to, from)
     tree to, from;
{
  for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
    {
      if (TREE_CODE (to) != TREE_CODE (from))
        return 0;

      if (TREE_CODE (from) == OFFSET_TYPE
          && comptypes (TYPE_OFFSET_BASETYPE (to),
                        TYPE_OFFSET_BASETYPE (from), 
                        COMPARE_BASE | COMPARE_RELAXED))
        continue;

      if (TREE_CODE (to) != POINTER_TYPE)
        return comptypes
          (TYPE_MAIN_VARIANT (to), TYPE_MAIN_VARIANT (from), 
           COMPARE_BASE | COMPARE_RELAXED);
    }
}

/* Like comp_ptr_ttypes, for const_cast.  */

static int
comp_ptr_ttypes_const (to, from)
     tree to, from;
{
  for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
    {
      if (TREE_CODE (to) != TREE_CODE (from))
        return 0;

      if (TREE_CODE (from) == OFFSET_TYPE
          && same_type_p (TYPE_OFFSET_BASETYPE (from),
                          TYPE_OFFSET_BASETYPE (to)))
          continue;

      if (TREE_CODE (to) != POINTER_TYPE)
        return same_type_p (TYPE_MAIN_VARIANT (to), 
                            TYPE_MAIN_VARIANT (from));
    }
}

/* Like comp_ptr_ttypes, for reinterpret_cast.  */

static int
comp_ptr_ttypes_reinterpret (to, from)
     tree to, from;
{
  int constp = 1;

  for (; ; to = TREE_TYPE (to), from = TREE_TYPE (from))
    {
      if (TREE_CODE (from) == OFFSET_TYPE)
        from = TREE_TYPE (from);
      if (TREE_CODE (to) == OFFSET_TYPE)
        to = TREE_TYPE (to);

      /* Const and volatile mean something different for function types,
         so the usual checks are not appropriate.  */
      if (TREE_CODE (from) != FUNCTION_TYPE && TREE_CODE (from) != METHOD_TYPE
          && TREE_CODE (to) != FUNCTION_TYPE && TREE_CODE (to) != METHOD_TYPE)
        {
          if (!at_least_as_qualified_p (to, from))
            return 0;

          if (! constp
              && !at_least_as_qualified_p (from, to))
            return 0;
          constp &= TYPE_READONLY (to);
        }

      if (TREE_CODE (from) != POINTER_TYPE
          || TREE_CODE (to) != POINTER_TYPE)
        return 1;
    }
}

/* Recursively examines the array elements of TYPE, until a non-array
   element type is found.  */

tree
strip_array_types (type)
     tree type;
{
  while (TREE_CODE (type) == ARRAY_TYPE)
    type = TREE_TYPE (type);

  return type;
}

/* Returns the type-qualifier set corresponding to TYPE.  */

int
cp_type_quals (type)
     tree type;
{
  return TYPE_QUALS (strip_array_types (type));
}

/* Returns non-zero if the TYPE contains a mutable member */

int
cp_has_mutable_p (type)
     tree type;
{
  while (TREE_CODE (type) == ARRAY_TYPE)
    type = TREE_TYPE (type);

  return CLASS_TYPE_P (type) && CLASSTYPE_HAS_MUTABLE (type);
}

/* Subroutine of casts_away_constness.  Make T1 and T2 point at
   exemplar types such that casting T1 to T2 is casting away castness
   if and only if there is no implicit conversion from T1 to T2.  */

static void
casts_away_constness_r (t1, t2)
     tree *t1;
     tree *t2;
{
  int quals1;
  int quals2;

  /* [expr.const.cast]

     For multi-level pointer to members and multi-level mixed pointers
     and pointers to members (conv.qual), the "member" aspect of a
     pointer to member level is ignored when determining if a const
     cv-qualifier has been cast away.  */
  if (TYPE_PTRMEM_P (*t1))
    *t1 = build_pointer_type (TREE_TYPE (TREE_TYPE (*t1)));
  if (TYPE_PTRMEM_P (*t2))
    *t2 = build_pointer_type (TREE_TYPE (TREE_TYPE (*t2)));

  /* [expr.const.cast]

     For  two  pointer types:

            X1 is T1cv1,1 * ... cv1,N *   where T1 is not a pointer type
            X2 is T2cv2,1 * ... cv2,M *   where T2 is not a pointer type
            K is min(N,M)

     casting from X1 to X2 casts away constness if, for a non-pointer
     type T there does not exist an implicit conversion (clause
     _conv_) from:

            Tcv1,(N-K+1) * cv1,(N-K+2) * ... cv1,N *
      
     to

            Tcv2,(M-K+1) * cv2,(M-K+2) * ... cv2,M *.  */

  if (TREE_CODE (*t1) != POINTER_TYPE
      || TREE_CODE (*t2) != POINTER_TYPE)
    {
      *t1 = cp_build_qualified_type (void_type_node,
                                     CP_TYPE_QUALS (*t1));
      *t2 = cp_build_qualified_type (void_type_node,
                                     CP_TYPE_QUALS (*t2));
      return;
    }
  
  quals1 = CP_TYPE_QUALS (*t1);
  quals2 = CP_TYPE_QUALS (*t2);
  *t1 = TREE_TYPE (*t1);
  *t2 = TREE_TYPE (*t2);
  casts_away_constness_r (t1, t2);
  *t1 = build_pointer_type (*t1);
  *t2 = build_pointer_type (*t2);
  *t1 = cp_build_qualified_type (*t1, quals1);
  *t2 = cp_build_qualified_type (*t2, quals2);
}

/* Returns non-zero if casting from TYPE1 to TYPE2 casts away
   constness.  */

static int
casts_away_constness (t1, t2)
     tree t1;
     tree t2;
{
  if (TREE_CODE (t2) == REFERENCE_TYPE)
    {
      /* [expr.const.cast]
         
         Casting from an lvalue of type T1 to an lvalue of type T2
         using a reference cast casts away constness if a cast from an
         rvalue of type "pointer to T1" to the type "pointer to T2"
         casts away constness.  */
      t1 = (TREE_CODE (t1) == REFERENCE_TYPE
            ? TREE_TYPE (t1) : t1);
      return casts_away_constness (build_pointer_type (t1),
                                   build_pointer_type (TREE_TYPE (t2)));
    }

  if (TYPE_PTRMEM_P (t1) && TYPE_PTRMEM_P (t2))
    /* [expr.const.cast]
       
       Casting from an rvalue of type "pointer to data member of X
       of type T1" to the type "pointer to data member of Y of type
       T2" casts away constness if a cast from an rvalue of type
       "poitner to T1" to the type "pointer to T2" casts away
       constness.  */
    return casts_away_constness
      (build_pointer_type (TREE_TYPE (TREE_TYPE (t1))),
       build_pointer_type (TREE_TYPE (TREE_TYPE (t2))));

  /* Casting away constness is only something that makes sense for
     pointer or reference types.  */
  if (TREE_CODE (t1) != POINTER_TYPE 
      || TREE_CODE (t2) != POINTER_TYPE)
    return 0;

  /* Top-level qualifiers don't matter.  */
  t1 = TYPE_MAIN_VARIANT (t1);
  t2 = TYPE_MAIN_VARIANT (t2);
  casts_away_constness_r (&t1, &t2);
  if (!can_convert (t2, t1))
    return 1;

  return 0;
}