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

/* Functions related to invoking methods and overloaded functions.
   Copyright (C) 1987, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
   Free Software Foundation, Inc.
   Contributed by Michael Tiemann (tiemann@cygnus.com) and
   modified by Brendan Kehoe (brendan@cygnus.com).

This file is part of GCC.

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

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

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to
the Free Software Foundation, 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */


/* High-level class interface.  */

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

/* The various kinds of conversion.  */

typedef enum conversion_kind {
  ck_identity,
  ck_lvalue,
  ck_qual,
  ck_std,
  ck_ptr,
  ck_pmem,
  ck_base,
  ck_ref_bind,
  ck_user,
  ck_ambig,
  ck_rvalue
} conversion_kind;

/* The rank of the conversion.  Order of the enumerals matters; better
   conversions should come earlier in the list.  */

typedef enum conversion_rank {
  cr_identity,
  cr_exact,
  cr_promotion,
  cr_std,
  cr_pbool,
  cr_user,
  cr_ellipsis,
  cr_bad
} conversion_rank;

/* An implicit conversion sequence, in the sense of [over.best.ics].
   The first conversion to be performed is at the end of the chain.
   That conversion is always a cr_identity conversion.  */

typedef struct conversion conversion;
struct conversion {
  /* The kind of conversion represented by this step.  */
  conversion_kind kind;
  /* The rank of this conversion.  */
  conversion_rank rank;
  BOOL_BITFIELD user_conv_p : 1;
  BOOL_BITFIELD ellipsis_p : 1;
  BOOL_BITFIELD this_p : 1;
  BOOL_BITFIELD bad_p : 1;
  /* If KIND is ck_ref_bind ck_base_conv, true to indicate that a
     temporary should be created to hold the result of the
     conversion.  */
  BOOL_BITFIELD need_temporary_p : 1;
  /* If KIND is ck_identity or ck_base_conv, true to indicate that the
     copy constructor must be accessible, even though it is not being
     used.  */
  BOOL_BITFIELD check_copy_constructor_p : 1;
  /* If KIND is ck_ptr or ck_pmem, true to indicate that a conversion
     from a pointer-to-derived to pointer-to-base is being performed.  */
  BOOL_BITFIELD base_p : 1;
  /* The type of the expression resulting from the conversion.  */
  tree type;
  union {
    /* The next conversion in the chain.  Since the conversions are
       arranged from outermost to innermost, the NEXT conversion will
       actually be performed before this conversion.  This variant is
       used only when KIND is neither ck_identity nor ck_ambig.  */
    conversion *next;
    /* The expression at the beginning of the conversion chain.  This
       variant is used only if KIND is ck_identity or ck_ambig.  */
    tree expr;
  } u;
  /* The function candidate corresponding to this conversion
     sequence.  This field is only used if KIND is ck_user.  */
  struct z_candidate *cand;
};

#define CONVERSION_RANK(NODE)                   \
  ((NODE)->bad_p ? cr_bad                       \
   : (NODE)->ellipsis_p ? cr_ellipsis           \
   : (NODE)->user_conv_p ? cr_user              \
   : (NODE)->rank)

static struct obstack conversion_obstack;
static bool conversion_obstack_initialized;

static struct z_candidate * tourney (struct z_candidate *);
static int equal_functions (tree, tree);
static int joust (struct z_candidate *, struct z_candidate *, bool);
static int compare_ics (conversion *, conversion *);
static tree build_over_call (struct z_candidate *, int);
static tree build_java_interface_fn_ref (tree, tree);
#define convert_like(CONV, EXPR)                                \
  convert_like_real ((CONV), (EXPR), NULL_TREE, 0, 0,           \
                     /*issue_conversion_warnings=*/true,        \
                     /*c_cast_p=*/false)
#define convert_like_with_context(CONV, EXPR, FN, ARGNO)        \
  convert_like_real ((CONV), (EXPR), (FN), (ARGNO), 0,          \
                     /*issue_conversion_warnings=*/true,        \
                     /*c_cast_p=*/false)
static tree convert_like_real (conversion *, tree, tree, int, int, bool,
                               bool);
static void op_error (enum tree_code, enum tree_code, tree, tree,
                      tree, const char *);
static tree build_object_call (tree, tree);
static tree resolve_args (tree);
static struct z_candidate *build_user_type_conversion_1 (tree, tree, int);
static void print_z_candidate (const char *, struct z_candidate *);
static void print_z_candidates (struct z_candidate *);
static tree build_this (tree);
static struct z_candidate *splice_viable (struct z_candidate *, bool, bool *);
static bool any_strictly_viable (struct z_candidate *);
static struct z_candidate *add_template_candidate
        (struct z_candidate **, tree, tree, tree, tree, tree,
         tree, tree, int, unification_kind_t);
static struct z_candidate *add_template_candidate_real
        (struct z_candidate **, tree, tree, tree, tree, tree,
         tree, tree, int, tree, unification_kind_t);
static struct z_candidate *add_template_conv_candidate
        (struct z_candidate **, tree, tree, tree, tree, tree, tree);
static void add_builtin_candidates
        (struct z_candidate **, enum tree_code, enum tree_code,
         tree, tree *, int);
static void add_builtin_candidate
        (struct z_candidate **, enum tree_code, enum tree_code,
         tree, tree, tree, tree *, tree *, int);
static bool is_complete (tree);
static void build_builtin_candidate
        (struct z_candidate **, tree, tree, tree, tree *, tree *,
         int);
static struct z_candidate *add_conv_candidate
        (struct z_candidate **, tree, tree, tree, tree, tree);
static struct z_candidate *add_function_candidate
        (struct z_candidate **, tree, tree, tree, tree, tree, int);
static conversion *implicit_conversion (tree, tree, tree, bool, int);
static conversion *standard_conversion (tree, tree, tree, bool, int);
static conversion *reference_binding (tree, tree, tree, int);
static conversion *build_conv (conversion_kind, tree, conversion *);
static bool is_subseq (conversion *, conversion *);
static tree maybe_handle_ref_bind (conversion **);
static void maybe_handle_implicit_object (conversion **);
static struct z_candidate *add_candidate
        (struct z_candidate **, tree, tree, size_t,
         conversion **, tree, tree, int);
static tree source_type (conversion *);
static void add_warning (struct z_candidate *, struct z_candidate *);
static bool reference_related_p (tree, tree);
static bool reference_compatible_p (tree, tree);
static conversion *convert_class_to_reference (tree, tree, tree);
static conversion *direct_reference_binding (tree, conversion *);
static bool promoted_arithmetic_type_p (tree);
static conversion *conditional_conversion (tree, tree);
static char *name_as_c_string (tree, tree, bool *);
static tree call_builtin_trap (void);
static tree prep_operand (tree);
static void add_candidates (tree, tree, tree, bool, tree, tree,
                            int, struct z_candidate **);
static conversion *merge_conversion_sequences (conversion *, conversion *);
static bool magic_varargs_p (tree);
typedef void (*diagnostic_fn_t) (const char *, ...) ATTRIBUTE_GCC_CXXDIAG(1,2);
static tree build_temp (tree, tree, int, diagnostic_fn_t *);
static void check_constructor_callable (tree, tree);

/* Returns nonzero iff the destructor name specified in NAME matches BASETYPE.
   NAME can take many forms...  */

bool
check_dtor_name (tree basetype, tree name)
{
  /* Just accept something we've already complained about.  */
  if (name == error_mark_node)
    return true;

  if (TREE_CODE (name) == TYPE_DECL)
    name = TREE_TYPE (name);
  else if (TYPE_P (name))
    /* OK */;
  else if (TREE_CODE (name) == IDENTIFIER_NODE)
    {
      if ((IS_AGGR_TYPE (basetype) && name == constructor_name (basetype))
          || (TREE_CODE (basetype) == ENUMERAL_TYPE
              && name == TYPE_IDENTIFIER (basetype)))
        return true;
      else
        name = get_type_value (name);
    }
  else
    {
      /* In the case of:

         template <class T> struct S { ~S(); };
         int i;
         i.~S();

         NAME will be a class template.  */
      gcc_assert (DECL_CLASS_TEMPLATE_P (name));
      return false;
    }

  if (!name)
    return false;
  return same_type_p (TYPE_MAIN_VARIANT (basetype), TYPE_MAIN_VARIANT (name));
}

/* We want the address of a function or method.  We avoid creating a
   pointer-to-member function.  */

tree
build_addr_func (tree function)
{
  tree type = TREE_TYPE (function);

  /* We have to do these by hand to avoid real pointer to member
     functions.  */
  if (TREE_CODE (type) == METHOD_TYPE)
    {
      if (TREE_CODE (function) == OFFSET_REF)
        {
          tree object = build_address (TREE_OPERAND (function, 0));
          return get_member_function_from_ptrfunc (&object,
                                                   TREE_OPERAND (function, 1));
        }
      function = build_address (function);
    }
  else
    function = decay_conversion (function);

  return function;
}

/* Build a CALL_EXPR, we can handle FUNCTION_TYPEs, METHOD_TYPEs, or
   POINTER_TYPE to those.  Note, pointer to member function types
   (TYPE_PTRMEMFUNC_P) must be handled by our callers.  There are
   two variants.  build_call_a is the primitive taking an array of
   arguments, while build_call_n is a wrapper that handles varargs.  */

tree
build_call_n (tree function, int n, ...)
{
  if (n == 0)
    return build_call_a (function, 0, NULL);
  else
    {
      tree *argarray = (tree *) alloca (n * sizeof (tree));
      va_list ap;
      int i;

      va_start (ap, n);
      for (i = 0; i < n; i++)
        argarray[i] = va_arg (ap, tree);
      va_end (ap);
      return build_call_a (function, n, argarray);
    }
}

tree
build_call_a (tree function, int n, tree *argarray)
{
  int is_constructor = 0;
  int nothrow;
  tree decl;
  tree result_type;
  tree fntype;
  int i;

  function = build_addr_func (function);

  gcc_assert (TYPE_PTR_P (TREE_TYPE (function)));
  fntype = TREE_TYPE (TREE_TYPE (function));
  gcc_assert (TREE_CODE (fntype) == FUNCTION_TYPE
              || TREE_CODE (fntype) == METHOD_TYPE);
  result_type = TREE_TYPE (fntype);

  if (TREE_CODE (function) == ADDR_EXPR
      && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
    {
      decl = TREE_OPERAND (function, 0);
      if (!TREE_USED (decl))
        {
          /* We invoke build_call directly for several library
             functions.  These may have been declared normally if
             we're building libgcc, so we can't just check
             DECL_ARTIFICIAL.  */
          gcc_assert (DECL_ARTIFICIAL (decl)
                      || !strncmp (IDENTIFIER_POINTER (DECL_NAME (decl)),
                                   "__", 2));
          mark_used (decl);
        }
    }
  else
    decl = NULL_TREE;

  /* We check both the decl and the type; a function may be known not to
     throw without being declared throw().  */
  nothrow = ((decl && TREE_NOTHROW (decl))
             || TYPE_NOTHROW_P (TREE_TYPE (TREE_TYPE (function))));

  if (decl && TREE_THIS_VOLATILE (decl) && cfun)
    current_function_returns_abnormally = 1;

  if (decl && TREE_DEPRECATED (decl))
    warn_deprecated_use (decl);
  require_complete_eh_spec_types (fntype, decl);

  if (decl && DECL_CONSTRUCTOR_P (decl))
    is_constructor = 1;

  /* Don't pass empty class objects by value.  This is useful
     for tags in STL, which are used to control overload resolution.
     We don't need to handle other cases of copying empty classes.  */
  if (! decl || ! DECL_BUILT_IN (decl))
    for (i = 0; i < n; i++)
      if (is_empty_class (TREE_TYPE (argarray[i]))
          && ! TREE_ADDRESSABLE (TREE_TYPE (argarray[i])))
        {
          tree t = build0 (EMPTY_CLASS_EXPR, TREE_TYPE (argarray[i]));
          argarray[i] = build2 (COMPOUND_EXPR, TREE_TYPE (t),
                                argarray[i], t);
        }

  function = build_call_array (result_type, function, n, argarray);
  TREE_HAS_CONSTRUCTOR (function) = is_constructor;
  TREE_NOTHROW (function) = nothrow;

  return function;
}

/* Build something of the form ptr->method (args)
   or object.method (args).  This can also build
   calls to constructors, and find friends.

   Member functions always take their class variable
   as a pointer.

   INSTANCE is a class instance.

   NAME is the name of the method desired, usually an IDENTIFIER_NODE.

   PARMS help to figure out what that NAME really refers to.

   BASETYPE_PATH, if non-NULL, contains a chain from the type of INSTANCE
   down to the real instance type to use for access checking.  We need this
   information to get protected accesses correct.

   FLAGS is the logical disjunction of zero or more LOOKUP_
   flags.  See cp-tree.h for more info.

   If this is all OK, calls build_function_call with the resolved
   member function.

   This function must also handle being called to perform
   initialization, promotion/coercion of arguments, and
   instantiation of default parameters.

   Note that NAME may refer to an instance variable name.  If
   `operator()()' is defined for the type of that field, then we return
   that result.  */

/* New overloading code.  */

typedef struct z_candidate z_candidate;

typedef struct candidate_warning candidate_warning;
struct candidate_warning {
  z_candidate *loser;
  candidate_warning *next;
};

struct z_candidate {
  /* The FUNCTION_DECL that will be called if this candidate is
     selected by overload resolution.  */
  tree fn;
  /* The arguments to use when calling this function.  */
  tree args;
  /* The implicit conversion sequences for each of the arguments to
     FN.  */
  conversion **convs;
  /* The number of implicit conversion sequences.  */
  size_t num_convs;
  /* If FN is a user-defined conversion, the standard conversion
     sequence from the type returned by FN to the desired destination
     type.  */
  conversion *second_conv;
  int viable;
  /* If FN is a member function, the binfo indicating the path used to
     qualify the name of FN at the call site.  This path is used to
     determine whether or not FN is accessible if it is selected by
     overload resolution.  The DECL_CONTEXT of FN will always be a
     (possibly improper) base of this binfo.  */
  tree access_path;
  /* If FN is a non-static member function, the binfo indicating the
     subobject to which the `this' pointer should be converted if FN
     is selected by overload resolution.  The type pointed to the by
     the `this' pointer must correspond to the most derived class
     indicated by the CONVERSION_PATH.  */
  tree conversion_path;
  tree template_decl;
  candidate_warning *warnings;
  z_candidate *next;
};

/* Returns true iff T is a null pointer constant in the sense of
   [conv.ptr].  */

bool
null_ptr_cst_p (tree t)
{
  /* [conv.ptr]

     A null pointer constant is an integral constant expression
     (_expr.const_) rvalue of integer type that evaluates to zero.  */
  t = integral_constant_value (t);
  if (t == null_node)
    return true;
  if (CP_INTEGRAL_TYPE_P (TREE_TYPE (t)) && integer_zerop (t))
    {
      STRIP_NOPS (t);
      if (!TREE_OVERFLOW (t))
        return true;
    }
  return false;
}

/* Returns nonzero if PARMLIST consists of only default parms and/or
   ellipsis.  */

bool
sufficient_parms_p (tree parmlist)
{
  for (; parmlist && parmlist != void_list_node;
       parmlist = TREE_CHAIN (parmlist))
    if (!TREE_PURPOSE (parmlist))
      return false;
  return true;
}

/* Allocate N bytes of memory from the conversion obstack.  The memory
   is zeroed before being returned.  */

static void *
conversion_obstack_alloc (size_t n)
{
  void *p;
  if (!conversion_obstack_initialized)
    {
      gcc_obstack_init (&conversion_obstack);
      conversion_obstack_initialized = true;
    }
  p = obstack_alloc (&conversion_obstack, n);
  memset (p, 0, n);
  return p;
}

/* Dynamically allocate a conversion.  */

static conversion *
alloc_conversion (conversion_kind kind)
{
  conversion *c;
  c = (conversion *) conversion_obstack_alloc (sizeof (conversion));
  c->kind = kind;
  return c;
}

#ifdef ENABLE_CHECKING

/* Make sure that all memory on the conversion obstack has been
   freed.  */

void
validate_conversion_obstack (void)
{
  if (conversion_obstack_initialized)
    gcc_assert ((obstack_next_free (&conversion_obstack)
                 == obstack_base (&conversion_obstack)));
}

#endif /* ENABLE_CHECKING */

/* Dynamically allocate an array of N conversions.  */

static conversion **
alloc_conversions (size_t n)
{
  return (conversion **) conversion_obstack_alloc (n * sizeof (conversion *));
}

static conversion *
build_conv (conversion_kind code, tree type, conversion *from)
{
  conversion *t;
  conversion_rank rank = CONVERSION_RANK (from);

  /* We can't use buildl1 here because CODE could be USER_CONV, which
     takes two arguments.  In that case, the caller is responsible for
     filling in the second argument.  */
  t = alloc_conversion (code);
  t->type = type;
  t->u.next = from;

  switch (code)
    {
    case ck_ptr:
    case ck_pmem:
    case ck_base:
    case ck_std:
      if (rank < cr_std)
        rank = cr_std;
      break;

    case ck_qual:
      if (rank < cr_exact)
        rank = cr_exact;
      break;

    default:
      break;
    }
  t->rank = rank;
  t->user_conv_p = (code == ck_user || from->user_conv_p);
  t->bad_p = from->bad_p;
  t->base_p = false;
  return t;
}

/* Build a representation of the identity conversion from EXPR to
   itself.  The TYPE should match the type of EXPR, if EXPR is non-NULL.  */

static conversion *
build_identity_conv (tree type, tree expr)
{
  conversion *c;

  c = alloc_conversion (ck_identity);
  c->type = type;
  c->u.expr = expr;

  return c;
}

/* Converting from EXPR to TYPE was ambiguous in the sense that there
   were multiple user-defined conversions to accomplish the job.
   Build a conversion that indicates that ambiguity.  */

static conversion *
build_ambiguous_conv (tree type, tree expr)
{
  conversion *c;

  c = alloc_conversion (ck_ambig);
  c->type = type;
  c->u.expr = expr;

  return c;
}

tree
strip_top_quals (tree t)
{
  if (TREE_CODE (t) == ARRAY_TYPE)
    return t;
  return cp_build_qualified_type (t, 0);
}

/* Returns the standard conversion path (see [conv]) from type FROM to type
   TO, if any.  For proper handling of null pointer constants, you must
   also pass the expression EXPR to convert from.  If C_CAST_P is true,
   this conversion is coming from a C-style cast.  */

static conversion *
standard_conversion (tree to, tree from, tree expr, bool c_cast_p,
                     int flags)
{
  enum tree_code fcode, tcode;
  conversion *conv;
  bool fromref = false;

  to = non_reference (to);
  if (TREE_CODE (from) == REFERENCE_TYPE)
    {
      fromref = true;
      from = TREE_TYPE (from);
    }
  to = strip_top_quals (to);
  from = strip_top_quals (from);

  if ((TYPE_PTRFN_P (to) || TYPE_PTRMEMFUNC_P (to))
      && expr && type_unknown_p (expr))
    {
      expr = instantiate_type (to, expr, tf_conv);
      if (expr == error_mark_node)
        return NULL;
      from = TREE_TYPE (expr);
    }

  fcode = TREE_CODE (from);
  tcode = TREE_CODE (to);

  conv = build_identity_conv (from, expr);
  if (fcode == FUNCTION_TYPE)
    {
      from = build_pointer_type (from);
      fcode = TREE_CODE (from);
      conv = build_conv (ck_lvalue, from, conv);
    }
  else if (fcode == ARRAY_TYPE)
    {
      from = build_pointer_type (TREE_TYPE (from));
      fcode = TREE_CODE (from);
      conv = build_conv (ck_lvalue, from, conv);
    }
  else if (fromref || (expr && lvalue_p (expr)))
    {
      if (expr)
        {
          tree bitfield_type;
          bitfield_type = is_bitfield_expr_with_lowered_type (expr);
          if (bitfield_type)
            from = strip_top_quals (bitfield_type);
        }
      conv = build_conv (ck_rvalue, from, conv);
    }

   /* Allow conversion between `__complex__' data types.  */
  if (tcode == COMPLEX_TYPE && fcode == COMPLEX_TYPE)
    {
      /* The standard conversion sequence to convert FROM to TO is
         the standard conversion sequence to perform componentwise
         conversion.  */
      conversion *part_conv = standard_conversion
        (TREE_TYPE (to), TREE_TYPE (from), NULL_TREE, c_cast_p, flags);

      if (part_conv)
        {
          conv = build_conv (part_conv->kind, to, conv);
          conv->rank = part_conv->rank;
        }
      else
        conv = NULL;

      return conv;
    }

  if (same_type_p (from, to))
    return conv;

  if ((tcode == POINTER_TYPE || TYPE_PTR_TO_MEMBER_P (to))
      && expr && null_ptr_cst_p (expr))
    conv = build_conv (ck_std, to, conv);
  else if ((tcode == INTEGER_TYPE && fcode == POINTER_TYPE)
           || (tcode == POINTER_TYPE && fcode == INTEGER_TYPE))
    {
      /* For backwards brain damage compatibility, allow interconversion of
         pointers and integers with a pedwarn.  */
      conv = build_conv (ck_std, to, conv);
      conv->bad_p = true;
    }
  else if (tcode == ENUMERAL_TYPE && fcode == INTEGER_TYPE)
    {
      /* For backwards brain damage compatibility, allow interconversion of
         enums and integers with a pedwarn.  */
      conv = build_conv (ck_std, to, conv);
      conv->bad_p = true;
    }
  else if ((tcode == POINTER_TYPE && fcode == POINTER_TYPE)
           || (TYPE_PTRMEM_P (to) && TYPE_PTRMEM_P (from)))
    {
      tree to_pointee;
      tree from_pointee;

      if (tcode == POINTER_TYPE
          && same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (from),
                                                        TREE_TYPE (to)))
        ;
      else if (VOID_TYPE_P (TREE_TYPE (to))
               && !TYPE_PTRMEM_P (from)
               && TREE_CODE (TREE_TYPE (from)) != FUNCTION_TYPE)
        {
          from = build_pointer_type
            (cp_build_qualified_type (void_type_node,
                                      cp_type_quals (TREE_TYPE (from))));
          conv = build_conv (ck_ptr, from, conv);
        }
      else if (TYPE_PTRMEM_P (from))
        {
          tree fbase = TYPE_PTRMEM_CLASS_TYPE (from);
          tree tbase = TYPE_PTRMEM_CLASS_TYPE (to);

          if (DERIVED_FROM_P (fbase, tbase)
              && (same_type_ignoring_top_level_qualifiers_p
                  (TYPE_PTRMEM_POINTED_TO_TYPE (from),
                   TYPE_PTRMEM_POINTED_TO_TYPE (to))))
            {
              from = build_ptrmem_type (tbase,
                                        TYPE_PTRMEM_POINTED_TO_TYPE (from));
              conv = build_conv (ck_pmem, from, conv);
            }
          else if (!same_type_p (fbase, tbase))
            return NULL;
        }
      else if (IS_AGGR_TYPE (TREE_TYPE (from))
               && IS_AGGR_TYPE (TREE_TYPE (to))
               /* [conv.ptr]

                  An rvalue of type "pointer to cv D," where D is a
                  class type, can be converted to an rvalue of type
                  "pointer to cv B," where B is a base class (clause
                  _class.derived_) of D.  If B is an inaccessible
                  (clause _class.access_) or ambiguous
                  (_class.member.lookup_) base class of D, a program
                  that necessitates this conversion is ill-formed.
                  Therefore, we use DERIVED_FROM_P, and do not check
                  access or uniqueness.  */
               && DERIVED_FROM_P (TREE_TYPE (to), TREE_TYPE (from))
               /* If FROM is not yet complete, then we must be parsing
                  the body of a class.  We know what's derived from
                  what, but we can't actually perform a
                  derived-to-base conversion.  For example, in:

                     struct D : public B { 
                       static const int i = sizeof((B*)(D*)0);
                     };

                  the D*-to-B* conversion is a reinterpret_cast, not a
                  static_cast.  */
               && COMPLETE_TYPE_P (TREE_TYPE (from)))
        {
          from =
            cp_build_qualified_type (TREE_TYPE (to),
                                     cp_type_quals (TREE_TYPE (from)));
          from = build_pointer_type (from);
          conv = build_conv (ck_ptr, from, conv);
          conv->base_p = true;
        }

      if (tcode == POINTER_TYPE)
        {
          to_pointee = TREE_TYPE (to);
          from_pointee = TREE_TYPE (from);
        }
      else
        {
          to_pointee = TYPE_PTRMEM_POINTED_TO_TYPE (to);
          from_pointee = TYPE_PTRMEM_POINTED_TO_TYPE (from);
        }

      if (same_type_p (from, to))
        /* OK */;
      else if (c_cast_p && comp_ptr_ttypes_const (to, from))
        /* In a C-style cast, we ignore CV-qualification because we
           are allowed to perform a static_cast followed by a
           const_cast.  */
        conv = build_conv (ck_qual, to, conv);
      else if (!c_cast_p && comp_ptr_ttypes (to_pointee, from_pointee))
        conv = build_conv (ck_qual, to, conv);
      else if (expr && string_conv_p (to, expr, 0))
        /* converting from string constant to char *.  */
        conv = build_conv (ck_qual, to, conv);
      else if (ptr_reasonably_similar (to_pointee, from_pointee))
        {
          conv = build_conv (ck_ptr, to, conv);
          conv->bad_p = true;
        }
      else
        return NULL;

      from = to;
    }
  else if (TYPE_PTRMEMFUNC_P (to) && TYPE_PTRMEMFUNC_P (from))
    {
      tree fromfn = TREE_TYPE (TYPE_PTRMEMFUNC_FN_TYPE (from));
      tree tofn = TREE_TYPE (TYPE_PTRMEMFUNC_FN_TYPE (to));
      tree fbase = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (fromfn)));
      tree tbase = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (tofn)));

      if (!DERIVED_FROM_P (fbase, tbase)
          || !same_type_p (TREE_TYPE (fromfn), TREE_TYPE (tofn))
          || !compparms (TREE_CHAIN (TYPE_ARG_TYPES (fromfn)),
                         TREE_CHAIN (TYPE_ARG_TYPES (tofn)))
          || cp_type_quals (fbase) != cp_type_quals (tbase))
        return NULL;

      from = cp_build_qualified_type (tbase, cp_type_quals (fbase));
      from = build_method_type_directly (from,
                                         TREE_TYPE (fromfn),
                                         TREE_CHAIN (TYPE_ARG_TYPES (fromfn)));
      from = build_ptrmemfunc_type (build_pointer_type (from));
      conv = build_conv (ck_pmem, from, conv);
      conv->base_p = true;
    }
  else if (tcode == BOOLEAN_TYPE)
    {
      /* [conv.bool]

          An rvalue of arithmetic, enumeration, pointer, or pointer to
          member type can be converted to an rvalue of type bool.  */
      if (ARITHMETIC_TYPE_P (from)
          || fcode == ENUMERAL_TYPE
          || fcode == POINTER_TYPE
          || TYPE_PTR_TO_MEMBER_P (from))
        {
          conv = build_conv (ck_std, to, conv);
          if (fcode == POINTER_TYPE
              || TYPE_PTRMEM_P (from)
              || (TYPE_PTRMEMFUNC_P (from)
                  && conv->rank < cr_pbool))
            conv->rank = cr_pbool;
          return conv;
        }

      return NULL;
    }
  /* We don't check for ENUMERAL_TYPE here because there are no standard
     conversions to enum type.  */
  else if (tcode == INTEGER_TYPE || tcode == BOOLEAN_TYPE
           || tcode == REAL_TYPE)
    {
      if (! (INTEGRAL_CODE_P (fcode) || fcode == REAL_TYPE))
        return NULL;
      conv = build_conv (ck_std, to, conv);

      /* Give this a better rank if it's a promotion.  */
      if (same_type_p (to, type_promotes_to (from))
          && conv->u.next->rank <= cr_promotion)
        conv->rank = cr_promotion;
    }
  else if (fcode == VECTOR_TYPE && tcode == VECTOR_TYPE
           && vector_types_convertible_p (from, to, false))
    return build_conv (ck_std, to, conv);
  else if (!(flags & LOOKUP_CONSTRUCTOR_CALLABLE)
           && IS_AGGR_TYPE (to) && IS_AGGR_TYPE (from)
           && is_properly_derived_from (from, to))
    {
      if (conv->kind == ck_rvalue)
        conv = conv->u.next;
      conv = build_conv (ck_base, to, conv);
      /* The derived-to-base conversion indicates the initialization
         of a parameter with base type from an object of a derived
         type.  A temporary object is created to hold the result of
         the conversion.  */
      conv->need_temporary_p = true;
    }
  else
    return NULL;

  return conv;
}

/* Returns nonzero if T1 is reference-related to T2.  */

static bool
reference_related_p (tree t1, tree t2)
{
  t1 = TYPE_MAIN_VARIANT (t1);
  t2 = TYPE_MAIN_VARIANT (t2);

  /* [dcl.init.ref]

     Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
     to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
     of T2.  */
  return (same_type_p (t1, t2)
          || (CLASS_TYPE_P (t1) && CLASS_TYPE_P (t2)
              && DERIVED_FROM_P (t1, t2)));
}

/* Returns nonzero if T1 is reference-compatible with T2.  */

static bool
reference_compatible_p (tree t1, tree t2)
{
  /* [dcl.init.ref]

     "cv1 T1" is reference compatible with "cv2 T2" if T1 is
     reference-related to T2 and cv1 is the same cv-qualification as,
     or greater cv-qualification than, cv2.  */
  return (reference_related_p (t1, t2)
          && at_least_as_qualified_p (t1, t2));
}

/* Determine whether or not the EXPR (of class type S) can be
   converted to T as in [over.match.ref].  */

static conversion *
convert_class_to_reference (tree t, tree s, tree expr)
{
  tree conversions;
  tree arglist;
  conversion *conv;
  tree reference_type;
  struct z_candidate *candidates;
  struct z_candidate *cand;
  bool any_viable_p;

  conversions = lookup_conversions (s);
  if (!conversions)
    return NULL;

  /* [over.match.ref]

     Assuming that "cv1 T" is the underlying type of the reference
     being initialized, and "cv S" is the type of the initializer
     expression, with S a class type, the candidate functions are
     selected as follows:

     --The conversion functions of S and its base classes are
       considered.  Those that are not hidden within S and yield type
       "reference to cv2 T2", where "cv1 T" is reference-compatible
       (_dcl.init.ref_) with "cv2 T2", are candidate functions.

     The argument list has one argument, which is the initializer
     expression.  */

  candidates = 0;

  /* Conceptually, we should take the address of EXPR and put it in
     the argument list.  Unfortunately, however, that can result in
     error messages, which we should not issue now because we are just
     trying to find a conversion operator.  Therefore, we use NULL,
     cast to the appropriate type.  */
  arglist = build_int_cst (build_pointer_type (s), 0);
  arglist = build_tree_list (NULL_TREE, arglist);

  reference_type = build_reference_type (t);

  while (conversions)
    {
      tree fns = TREE_VALUE (conversions);

      for (; fns; fns = OVL_NEXT (fns))
        {
          tree f = OVL_CURRENT (fns);
          tree t2 = TREE_TYPE (TREE_TYPE (f));

          cand = NULL;

          /* If this is a template function, try to get an exact
             match.  */
          if (TREE_CODE (f) == TEMPLATE_DECL)
            {
              cand = add_template_candidate (&candidates,
                                             f, s,
                                             NULL_TREE,
                                             arglist,
                                             reference_type,
                                             TYPE_BINFO (s),
                                             TREE_PURPOSE (conversions),
                                             LOOKUP_NORMAL,
                                             DEDUCE_CONV);

              if (cand)
                {
                  /* Now, see if the conversion function really returns
                     an lvalue of the appropriate type.  From the
                     point of view of unification, simply returning an
                     rvalue of the right type is good enough.  */
                  f = cand->fn;
                  t2 = TREE_TYPE (TREE_TYPE (f));
                  if (TREE_CODE (t2) != REFERENCE_TYPE
                      || !reference_compatible_p (t, TREE_TYPE (t2)))
                    {
                      candidates = candidates->next;
                      cand = NULL;
                    }
                }
            }
          else if (TREE_CODE (t2) == REFERENCE_TYPE
                   && reference_compatible_p (t, TREE_TYPE (t2)))
            cand = add_function_candidate (&candidates, f, s, arglist,
                                           TYPE_BINFO (s),
                                           TREE_PURPOSE (conversions),
                                           LOOKUP_NORMAL);

          if (cand)
            {
              conversion *identity_conv;
              /* Build a standard conversion sequence indicating the
                 binding from the reference type returned by the
                 function to the desired REFERENCE_TYPE.  */
              identity_conv
                = build_identity_conv (TREE_TYPE (TREE_TYPE
                                                  (TREE_TYPE (cand->fn))),
                                       NULL_TREE);
              cand->second_conv
                = (direct_reference_binding
                   (reference_type, identity_conv));
              cand->second_conv->bad_p |= cand->convs[0]->bad_p;
            }
        }
      conversions = TREE_CHAIN (conversions);
    }

  candidates = splice_viable (candidates, pedantic, &any_viable_p);
  /* If none of the conversion functions worked out, let our caller
     know.  */
  if (!any_viable_p)
    return NULL;

  cand = tourney (candidates);
  if (!cand)
    return NULL;

  /* Now that we know that this is the function we're going to use fix
     the dummy first argument.  */
  cand->args = tree_cons (NULL_TREE,
                          build_this (expr),
                          TREE_CHAIN (cand->args));

  /* Build a user-defined conversion sequence representing the
     conversion.  */
  conv = build_conv (ck_user,
                     TREE_TYPE (TREE_TYPE (cand->fn)),
                     build_identity_conv (TREE_TYPE (expr), expr));
  conv->cand = cand;

  /* Merge it with the standard conversion sequence from the
     conversion function's return type to the desired type.  */
  cand->second_conv = merge_conversion_sequences (conv, cand->second_conv);

  if (cand->viable == -1)
    conv->bad_p = true;

  return cand->second_conv;
}

/* A reference of the indicated TYPE is being bound directly to the
   expression represented by the implicit conversion sequence CONV.
   Return a conversion sequence for this binding.  */

static conversion *
direct_reference_binding (tree type, conversion *conv)
{
  tree t;

  gcc_assert (TREE_CODE (type) == REFERENCE_TYPE);
  gcc_assert (TREE_CODE (conv->type) != REFERENCE_TYPE);

  t = TREE_TYPE (type);

  /* [over.ics.rank]

     When a parameter of reference type binds directly
     (_dcl.init.ref_) to an argument expression, the implicit
     conversion sequence is the identity conversion, unless the
     argument expression has a type that is a derived class of the
     parameter type, in which case the implicit conversion sequence is
     a derived-to-base Conversion.

     If the parameter binds directly to the result of applying a
     conversion function to the argument expression, the implicit
     conversion sequence is a user-defined conversion sequence
     (_over.ics.user_), with the second standard conversion sequence
     either an identity conversion or, if the conversion function
     returns an entity of a type that is a derived class of the
     parameter type, a derived-to-base conversion.  */
  if (!same_type_ignoring_top_level_qualifiers_p (t, conv->type))
    {
      /* Represent the derived-to-base conversion.  */
      conv = build_conv (ck_base, t, conv);
      /* We will actually be binding to the base-class subobject in
         the derived class, so we mark this conversion appropriately.
         That way, convert_like knows not to generate a temporary.  */
      conv->need_temporary_p = false;
    }
  return build_conv (ck_ref_bind, type, conv);
}

/* Returns the conversion path from type FROM to reference type TO for
   purposes of reference binding.  For lvalue binding, either pass a
   reference type to FROM or an lvalue expression to EXPR.  If the
   reference will be bound to a temporary, NEED_TEMPORARY_P is set for
   the conversion returned.  */

static conversion *
reference_binding (tree rto, tree rfrom, tree expr, int flags)
{
  conversion *conv = NULL;
  tree to = TREE_TYPE (rto);
  tree from = rfrom;
  bool related_p;
  bool compatible_p;
  cp_lvalue_kind lvalue_p = clk_none;

  if (TREE_CODE (to) == FUNCTION_TYPE && expr && type_unknown_p (expr))
    {
      expr = instantiate_type (to, expr, tf_none);
      if (expr == error_mark_node)
        return NULL;
      from = TREE_TYPE (expr);
    }

  if (TREE_CODE (from) == REFERENCE_TYPE)
    {
      /* Anything with reference type is an lvalue.  */
      lvalue_p = clk_ordinary;
      from = TREE_TYPE (from);
    }
  else if (expr)
    lvalue_p = real_lvalue_p (expr);

  /* Figure out whether or not the types are reference-related and
     reference compatible.  We have do do this after stripping
     references from FROM.  */
  related_p = reference_related_p (to, from);
  compatible_p = reference_compatible_p (to, from);

  if (lvalue_p && compatible_p)
    {
      /* [dcl.init.ref]

         If the initializer expression

         -- is an lvalue (but not an lvalue for a bit-field), and "cv1 T1"
            is reference-compatible with "cv2 T2,"

         the reference is bound directly to the initializer expression
         lvalue.  */
      conv = build_identity_conv (from, expr);
      conv = direct_reference_binding (rto, conv);
      if ((lvalue_p & clk_bitfield) != 0
          || ((lvalue_p & clk_packed) != 0 && !TYPE_PACKED (to)))
        /* For the purposes of overload resolution, we ignore the fact
           this expression is a bitfield or packed field. (In particular,
           [over.ics.ref] says specifically that a function with a
           non-const reference parameter is viable even if the
           argument is a bitfield.)

           However, when we actually call the function we must create
           a temporary to which to bind the reference.  If the
           reference is volatile, or isn't const, then we cannot make
           a temporary, so we just issue an error when the conversion
           actually occurs.  */
        conv->need_temporary_p = true;

      return conv;
    }
  else if (CLASS_TYPE_P (from) && !(flags & LOOKUP_NO_CONVERSION))
    {
      /* [dcl.init.ref]

         If the initializer expression

         -- has a class type (i.e., T2 is a class type) can be
            implicitly converted to an lvalue of type "cv3 T3," where
            "cv1 T1" is reference-compatible with "cv3 T3".  (this
            conversion is selected by enumerating the applicable
            conversion functions (_over.match.ref_) and choosing the
            best one through overload resolution.  (_over.match_).

        the reference is bound to the lvalue result of the conversion
        in the second case.  */
      conv = convert_class_to_reference (to, from, expr);
      if (conv)
        return conv;
    }

  /* From this point on, we conceptually need temporaries, even if we
     elide them.  Only the cases above are "direct bindings".  */
  if (flags & LOOKUP_NO_TEMP_BIND)
    return NULL;

  /* [over.ics.rank]

     When a parameter of reference type is not bound directly to an
     argument expression, the conversion sequence is the one required
     to convert the argument expression to the underlying type of the
     reference according to _over.best.ics_.  Conceptually, this
     conversion sequence corresponds to copy-initializing a temporary
     of the underlying type with the argument expression.  Any
     difference in top-level cv-qualification is subsumed by the
     initialization itself and does not constitute a conversion.  */

  /* [dcl.init.ref]

     Otherwise, the reference shall be to a non-volatile const type.  */
  if (!CP_TYPE_CONST_NON_VOLATILE_P (to))
    return NULL;

  /* [dcl.init.ref]

     If the initializer expression is an rvalue, with T2 a class type,
     and "cv1 T1" is reference-compatible with "cv2 T2", the reference
     is bound in one of the following ways:

     -- The reference is bound to the object represented by the rvalue
        or to a sub-object within that object.

     -- ...

     We use the first alternative.  The implicit conversion sequence
     is supposed to be same as we would obtain by generating a
     temporary.  Fortunately, if the types are reference compatible,
     then this is either an identity conversion or the derived-to-base
     conversion, just as for direct binding.  */
  if (CLASS_TYPE_P (from) && compatible_p)
    {
      conv = build_identity_conv (from, expr);
      conv = direct_reference_binding (rto, conv);
      if (!(flags & LOOKUP_CONSTRUCTOR_CALLABLE))
        conv->u.next->check_copy_constructor_p = true;
      return conv;
    }

  /* [dcl.init.ref]

     Otherwise, a temporary of type "cv1 T1" is created and
     initialized from the initializer expression using the rules for a
     non-reference copy initialization.  If T1 is reference-related to
     T2, cv1 must be the same cv-qualification as, or greater
     cv-qualification than, cv2; otherwise, the program is ill-formed.  */
  if (related_p && !at_least_as_qualified_p (to, from))
    return NULL;

  conv = implicit_conversion (to, from, expr, /*c_cast_p=*/false,
                              flags);
  if (!conv)
    return NULL;

  conv = build_conv (ck_ref_bind, rto, conv);
  /* This reference binding, unlike those above, requires the
     creation of a temporary.  */
  conv->need_temporary_p = true;

  return conv;
}

/* Returns the implicit conversion sequence (see [over.ics]) from type
   FROM to type TO.  The optional expression EXPR may affect the
   conversion.  FLAGS are the usual overloading flags.  Only
   LOOKUP_NO_CONVERSION is significant.  If C_CAST_P is true, this
   conversion is coming from a C-style cast.  */

static conversion *
implicit_conversion (tree to, tree from, tree expr, bool c_cast_p,
                     int flags)
{
  conversion *conv;

  if (from == error_mark_node || to == error_mark_node
      || expr == error_mark_node)
    return NULL;

  if (TREE_CODE (to) == REFERENCE_TYPE)
    conv = reference_binding (to, from, expr, flags);
  else
    conv = standard_conversion (to, from, expr, c_cast_p, flags);

  if (conv)
    return conv;

  if (expr != NULL_TREE
      && (IS_AGGR_TYPE (from)
          || IS_AGGR_TYPE (to))
      && (flags & LOOKUP_NO_CONVERSION) == 0)
    {
      struct z_candidate *cand;

      cand = build_user_type_conversion_1
        (to, expr, LOOKUP_ONLYCONVERTING);
      if (cand)
        conv = cand->second_conv;

      /* We used to try to bind a reference to a temporary here, but that
         is now handled by the recursive call to this function at the end
         of reference_binding.  */
      return conv;
    }

  return NULL;
}

/* Add a new entry to the list of candidates.  Used by the add_*_candidate
   functions.  */

static struct z_candidate *
add_candidate (struct z_candidate **candidates,
               tree fn, tree args,
               size_t num_convs, conversion **convs,
               tree access_path, tree conversion_path,
               int viable)
{
  struct z_candidate *cand = (struct z_candidate *)
    conversion_obstack_alloc (sizeof (struct z_candidate));

  cand->fn = fn;
  cand->args = args;
  cand->convs = convs;
  cand->num_convs = num_convs;
  cand->access_path = access_path;
  cand->conversion_path = conversion_path;
  cand->viable = viable;
  cand->next = *candidates;
  *candidates = cand;

  return cand;
}

/* Create an overload candidate for the function or method FN called with
   the argument list ARGLIST and add it to CANDIDATES.  FLAGS is passed on
   to implicit_conversion.

   CTYPE, if non-NULL, is the type we want to pretend this function
   comes from for purposes of overload resolution.  */

static struct z_candidate *
add_function_candidate (struct z_candidate **candidates,
                        tree fn, tree ctype, tree arglist,
                        tree access_path, tree conversion_path,
                        int flags)
{
  tree parmlist = TYPE_ARG_TYPES (TREE_TYPE (fn));
  int i, len;
  conversion **convs;
  tree parmnode, argnode;
  tree orig_arglist;
  int viable = 1;

  /* At this point we should not see any functions which haven't been
     explicitly declared, except for friend functions which will have
     been found using argument dependent lookup.  */
  gcc_assert (!DECL_ANTICIPATED (fn) || DECL_HIDDEN_FRIEND_P (fn));

  /* The `this', `in_chrg' and VTT arguments to constructors are not
     considered in overload resolution.  */
  if (DECL_CONSTRUCTOR_P (fn))
    {
      parmlist = skip_artificial_parms_for (fn, parmlist);
      orig_arglist = arglist;
      arglist = skip_artificial_parms_for (fn, arglist);
    }
  else
    orig_arglist = arglist;

  len = list_length (arglist);
  convs = alloc_conversions (len);

  /* 13.3.2 - Viable functions [over.match.viable]
     First, to be a viable function, a candidate function shall have enough
     parameters to agree in number with the arguments in the list.

     We need to check this first; otherwise, checking the ICSes might cause
     us to produce an ill-formed template instantiation.  */

  parmnode = parmlist;
  for (i = 0; i < len; ++i)
    {
      if (parmnode == NULL_TREE || parmnode == void_list_node)
        break;
      parmnode = TREE_CHAIN (parmnode);
    }

  if (i < len && parmnode)
    viable = 0;

  /* Make sure there are default args for the rest of the parms.  */
  else if (!sufficient_parms_p (parmnode))
    viable = 0;

  if (! viable)
    goto out;

  /* Second, for F to be a viable function, there shall exist for each
     argument an implicit conversion sequence that converts that argument
     to the corresponding parameter of F.  */

  parmnode = parmlist;
  argnode = arglist;

  for (i = 0; i < len; ++i)
    {
      tree arg = TREE_VALUE (argnode);
      tree argtype = lvalue_type (arg);
      conversion *t;
      int is_this;

      if (parmnode == void_list_node)
        break;

      is_this = (i == 0 && DECL_NONSTATIC_MEMBER_FUNCTION_P (fn)
                 && ! DECL_CONSTRUCTOR_P (fn));

      if (parmnode)
        {
          tree parmtype = TREE_VALUE (parmnode);

          /* The type of the implicit object parameter ('this') for
             overload resolution is not always the same as for the
             function itself; conversion functions are considered to
             be members of the class being converted, and functions
             introduced by a using-declaration are considered to be
             members of the class that uses them.

             Since build_over_call ignores the ICS for the `this'
             parameter, we can just change the parm type.  */
          if (ctype && is_this)
            {
              parmtype
                = build_qualified_type (ctype,
                                        TYPE_QUALS (TREE_TYPE (parmtype)));
              parmtype = build_pointer_type (parmtype);
            }

          t = implicit_conversion (parmtype, argtype, arg,
                                   /*c_cast_p=*/false, flags);
        }
      else
        {
          t = build_identity_conv (argtype, arg);
          t->ellipsis_p = true;
        }

      if (t && is_this)
        t->this_p = true;

      convs[i] = t;
      if (! t)
        {
          viable = 0;
          break;
        }

      if (t->bad_p)
        viable = -1;

      if (parmnode)
        parmnode = TREE_CHAIN (parmnode);
      argnode = TREE_CHAIN (argnode);
    }

 out:
  return add_candidate (candidates, fn, orig_arglist, len, convs,
                        access_path, conversion_path, viable);
}

/* Create an overload candidate for the conversion function FN which will
   be invoked for expression OBJ, producing a pointer-to-function which
   will in turn be called with the argument list ARGLIST, and add it to
   CANDIDATES.  FLAGS is passed on to implicit_conversion.

   Actually, we don't really care about FN; we care about the type it
   converts to.  There may be multiple conversion functions that will
   convert to that type, and we rely on build_user_type_conversion_1 to
   choose the best one; so when we create our candidate, we record the type
   instead of the function.  */

static struct z_candidate *
add_conv_candidate (struct z_candidate **candidates, tree fn, tree obj,
                    tree arglist, tree access_path, tree conversion_path)
{
  tree totype = TREE_TYPE (TREE_TYPE (fn));
  int i, len, viable, flags;
  tree parmlist, parmnode, argnode;
  conversion **convs;

  for (parmlist = totype; TREE_CODE (parmlist) != FUNCTION_TYPE; )
    parmlist = TREE_TYPE (parmlist);
  parmlist = TYPE_ARG_TYPES (parmlist);

  len = list_length (arglist) + 1;
  convs = alloc_conversions (len);
  parmnode = parmlist;
  argnode = arglist;
  viable = 1;
  flags = LOOKUP_NORMAL;

  /* Don't bother looking up the same type twice.  */
  if (*candidates && (*candidates)->fn == totype)
    return NULL;

  for (i = 0; i < len; ++i)
    {
      tree arg = i == 0 ? obj : TREE_VALUE (argnode);
      tree argtype = lvalue_type (arg);
      conversion *t;

      if (i == 0)
        t = implicit_conversion (totype, argtype, arg, /*c_cast_p=*/false,
                                 flags);
      else if (parmnode == void_list_node)
        break;
      else if (parmnode)
        t = implicit_conversion (TREE_VALUE (parmnode), argtype, arg,
                                 /*c_cast_p=*/false, flags);
      else
        {
          t = build_identity_conv (argtype, arg);
          t->ellipsis_p = true;
        }

      convs[i] = t;
      if (! t)
        break;

      if (t->bad_p)
        viable = -1;

      if (i == 0)
        continue;

      if (parmnode)
        parmnode = TREE_CHAIN (parmnode);
      argnode = TREE_CHAIN (argnode);
    }

  if (i < len)
    viable = 0;

  if (!sufficient_parms_p (parmnode))
    viable = 0;

  return add_candidate (candidates, totype, arglist, len, convs,
                        access_path, conversion_path, viable);
}

static void
build_builtin_candidate (struct z_candidate **candidates, tree fnname,
                         tree type1, tree type2, tree *args, tree *argtypes,
                         int flags)
{
  conversion *t;
  conversion **convs;
  size_t num_convs;
  int viable = 1, i;
  tree types[2];

  types[0] = type1;
  types[1] = type2;

  num_convs =  args[2] ? 3 : (args[1] ? 2 : 1);
  convs = alloc_conversions (num_convs);

  for (i = 0; i < 2; ++i)
    {
      if (! args[i])
        break;

      t = implicit_conversion (types[i], argtypes[i], args[i],
                               /*c_cast_p=*/false, flags);
      if (! t)
        {
          viable = 0;
          /* We need something for printing the candidate.  */
          t = build_identity_conv (types[i], NULL_TREE);
        }
      else if (t->bad_p)
        viable = 0;
      convs[i] = t;
    }

  /* For COND_EXPR we rearranged the arguments; undo that now.  */
  if (args[2])
    {
      convs[2] = convs[1];
      convs[1] = convs[0];
      t = implicit_conversion (boolean_type_node, argtypes[2], args[2],
                               /*c_cast_p=*/false, flags);
      if (t)
        convs[0] = t;
      else
        viable = 0;
    }

  add_candidate (candidates, fnname, /*args=*/NULL_TREE,
                 num_convs, convs,
                 /*access_path=*/NULL_TREE,
                 /*conversion_path=*/NULL_TREE,
                 viable);
}

static bool
is_complete (tree t)
{
  return COMPLETE_TYPE_P (complete_type (t));
}

/* Returns nonzero if TYPE is a promoted arithmetic type.  */

static bool
promoted_arithmetic_type_p (tree type)
{
  /* [over.built]

     In this section, the term promoted integral type is used to refer
     to those integral types which are preserved by integral promotion
     (including e.g.  int and long but excluding e.g.  char).
     Similarly, the term promoted arithmetic type refers to promoted
     integral types plus floating types.  */
  return ((INTEGRAL_TYPE_P (type)
           && same_type_p (type_promotes_to (type), type))
          || TREE_CODE (type) == REAL_TYPE);
}

/* Create any builtin operator overload candidates for the operator in
   question given the converted operand types TYPE1 and TYPE2.  The other
   args are passed through from add_builtin_candidates to
   build_builtin_candidate.

   TYPE1 and TYPE2 may not be permissible, and we must filter them.
   If CODE is requires candidates operands of the same type of the kind
   of which TYPE1 and TYPE2 are, we add both candidates
   CODE (TYPE1, TYPE1) and CODE (TYPE2, TYPE2).  */

static void
add_builtin_candidate (struct z_candidate **candidates, enum tree_code code,
                       enum tree_code code2, tree fnname, tree type1,
                       tree type2, tree *args, tree *argtypes, int flags)
{
  switch (code)
    {
    case POSTINCREMENT_EXPR:
    case POSTDECREMENT_EXPR:
      args[1] = integer_zero_node;
      type2 = integer_type_node;
      break;
    default:
      break;
    }

  switch (code)
    {

/* 4 For every pair T, VQ), where T is an arithmetic or  enumeration  type,
     and  VQ  is  either  volatile or empty, there exist candidate operator
     functions of the form
             VQ T&   operator++(VQ T&);
             T       operator++(VQ T&, int);
   5 For every pair T, VQ), where T is an enumeration type or an arithmetic
     type  other than bool, and VQ is either volatile or empty, there exist
     candidate operator functions of the form
             VQ T&   operator--(VQ T&);
             T       operator--(VQ T&, int);
   6 For every pair T, VQ), where T is  a  cv-qualified  or  cv-unqualified
     complete  object type, and VQ is either volatile or empty, there exist
     candidate operator functions of the form
             T*VQ&   operator++(T*VQ&);
             T*VQ&   operator--(T*VQ&);
             T*      operator++(T*VQ&, int);
             T*      operator--(T*VQ&, int);  */

    case POSTDECREMENT_EXPR:
    case PREDECREMENT_EXPR:
      if (TREE_CODE (type1) == BOOLEAN_TYPE)
        return;
    case POSTINCREMENT_EXPR:
    case PREINCREMENT_EXPR:
      if (ARITHMETIC_TYPE_P (type1) || TYPE_PTROB_P (type1))
        {
          type1 = build_reference_type (type1);
          break;
        }
      return;

/* 7 For every cv-qualified or cv-unqualified complete object type T, there
     exist candidate operator functions of the form

             T&      operator*(T*);

   8 For every function type T, there exist candidate operator functions of
     the form
             T&      operator*(T*);  */

    case INDIRECT_REF:
      if (TREE_CODE (type1) == POINTER_TYPE
          && (TYPE_PTROB_P (type1)
              || TREE_CODE (TREE_TYPE (type1)) == FUNCTION_TYPE))
        break;
      return;

/* 9 For every type T, there exist candidate operator functions of the form
             T*      operator+(T*);

   10For  every  promoted arithmetic type T, there exist candidate operator
     functions of the form
             T       operator+(T);
             T       operator-(T);  */

    case UNARY_PLUS_EXPR: /* unary + */
      if (TREE_CODE (type1) == POINTER_TYPE)
        break;
    case NEGATE_EXPR:
      if (ARITHMETIC_TYPE_P (type1))
        break;
      return;

/* 11For every promoted integral type T,  there  exist  candidate  operator
     functions of the form
             T       operator~(T);  */

    case BIT_NOT_EXPR:
      if (INTEGRAL_TYPE_P (type1))
        break;
      return;

/* 12For every quintuple C1, C2, T, CV1, CV2), where C2 is a class type, C1
     is the same type as C2 or is a derived class of C2, T  is  a  complete
     object type or a function type, and CV1 and CV2 are cv-qualifier-seqs,
     there exist candidate operator functions of the form
             CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
     where CV12 is the union of CV1 and CV2.  */

    case MEMBER_REF:
      if (TREE_CODE (type1) == POINTER_TYPE
          && TYPE_PTR_TO_MEMBER_P (type2))
        {
          tree c1 = TREE_TYPE (type1);
          tree c2 = TYPE_PTRMEM_CLASS_TYPE (type2);

          if (IS_AGGR_TYPE (c1) && DERIVED_FROM_P (c2, c1)
              && (TYPE_PTRMEMFUNC_P (type2)
                  || is_complete (TYPE_PTRMEM_POINTED_TO_TYPE (type2))))
            break;
        }
      return;

/* 13For every pair of promoted arithmetic types L and R, there exist  can-
     didate operator functions of the form
             LR      operator*(L, R);
             LR      operator/(L, R);
             LR      operator+(L, R);
             LR      operator-(L, R);
             bool    operator<(L, R);
             bool    operator>(L, R);
             bool    operator<=(L, R);
             bool    operator>=(L, R);
             bool    operator==(L, R);
             bool    operator!=(L, R);
     where  LR  is  the  result of the usual arithmetic conversions between
     types L and R.

   14For every pair of types T and I, where T  is  a  cv-qualified  or  cv-
     unqualified  complete  object  type and I is a promoted integral type,
     there exist candidate operator functions of the form
             T*      operator+(T*, I);
             T&      operator[](T*, I);
             T*      operator-(T*, I);
             T*      operator+(I, T*);
             T&      operator[](I, T*);

   15For every T, where T is a pointer to complete object type, there exist
     candidate operator functions of the form112)
             ptrdiff_t operator-(T, T);

   16For every pointer or enumeration type T, there exist candidate operator
     functions of the form
             bool    operator<(T, T);
             bool    operator>(T, T);
             bool    operator<=(T, T);
             bool    operator>=(T, T);
             bool    operator==(T, T);
             bool    operator!=(T, T);

   17For every pointer to member type T,  there  exist  candidate  operator
     functions of the form
             bool    operator==(T, T);
             bool    operator!=(T, T);  */

    case MINUS_EXPR:
      if (TYPE_PTROB_P (type1) && TYPE_PTROB_P (type2))
        break;
      if (TYPE_PTROB_P (type1) && INTEGRAL_TYPE_P (type2))
        {
          type2 = ptrdiff_type_node;
          break;
        }
    case MULT_EXPR:
    case TRUNC_DIV_EXPR:
      if (ARITHMETIC_TYPE_P (type1) && ARITHMETIC_TYPE_P (type2))
        break;
      return;

    case EQ_EXPR:
    case NE_EXPR:
      if ((TYPE_PTRMEMFUNC_P (type1) && TYPE_PTRMEMFUNC_P (type2))
          || (TYPE_PTRMEM_P (type1) && TYPE_PTRMEM_P (type2)))
        break;
      if (TYPE_PTR_TO_MEMBER_P (type1) && null_ptr_cst_p (args[1]))
        {
          type2 = type1;
          break;
        }
      if (TYPE_PTR_TO_MEMBER_P (type2) && null_ptr_cst_p (args[0]))
        {
          type1 = type2;
          break;
        }
      /* Fall through.  */
    case LT_EXPR:
    case GT_EXPR:
    case LE_EXPR:
    case GE_EXPR:
    case MAX_EXPR:
    case MIN_EXPR:
      if (ARITHMETIC_TYPE_P (type1) && ARITHMETIC_TYPE_P (type2))
        break;
      if (TYPE_PTR_P (type1) && TYPE_PTR_P (type2))
        break;
      if (TREE_CODE (type1) == ENUMERAL_TYPE 
          && TREE_CODE (type2) == ENUMERAL_TYPE)
        break;
      if (TYPE_PTR_P (type1) 
          && null_ptr_cst_p (args[1])
          && !uses_template_parms (type1))
        {
          type2 = type1;
          break;
        }
      if (null_ptr_cst_p (args[0]) 
          && TYPE_PTR_P (type2)
          && !uses_template_parms (type2))
        {
          type1 = type2;
          break;
        }
      return;

    case PLUS_EXPR:
      if (ARITHMETIC_TYPE_P (type1) && ARITHMETIC_TYPE_P (type2))
        break;
    case ARRAY_REF:
      if (INTEGRAL_TYPE_P (type1) && TYPE_PTROB_P (type2))
        {
          type1 = ptrdiff_type_node;
          break;
        }
      if (TYPE_PTROB_P (type1) && INTEGRAL_TYPE_P (type2))
        {
          type2 = ptrdiff_type_node;
          break;
        }
      return;

/* 18For  every pair of promoted integral types L and R, there exist candi-
     date operator functions of the form
             LR      operator%(L, R);
             LR      operator&(L, R);
             LR      operator^(L, R);
             LR      operator|(L, R);
             L       operator<<(L, R);
             L       operator>>(L, R);
     where LR is the result of the  usual  arithmetic  conversions  between
     types L and R.  */

    case TRUNC_MOD_EXPR:
    case BIT_AND_EXPR:
    case BIT_IOR_EXPR:
    case BIT_XOR_EXPR:
    case LSHIFT_EXPR:
    case RSHIFT_EXPR:
      if (INTEGRAL_TYPE_P (type1) && INTEGRAL_TYPE_P (type2))
        break;
      return;

/* 19For  every  triple  L, VQ, R), where L is an arithmetic or enumeration
     type, VQ is either volatile or empty, and R is a  promoted  arithmetic
     type, there exist candidate operator functions of the form
             VQ L&   operator=(VQ L&, R);
             VQ L&   operator*=(VQ L&, R);
             VQ L&   operator/=(VQ L&, R);
             VQ L&   operator+=(VQ L&, R);
             VQ L&   operator-=(VQ L&, R);

   20For  every  pair T, VQ), where T is any type and VQ is either volatile
     or empty, there exist candidate operator functions of the form
             T*VQ&   operator=(T*VQ&, T*);

   21For every pair T, VQ), where T is a pointer to member type and  VQ  is
     either  volatile or empty, there exist candidate operator functions of
     the form
             VQ T&   operator=(VQ T&, T);

   22For every triple  T,  VQ,  I),  where  T  is  a  cv-qualified  or  cv-
     unqualified  complete object type, VQ is either volatile or empty, and
     I is a promoted integral type, there exist  candidate  operator  func-
     tions of the form
             T*VQ&   operator+=(T*VQ&, I);
             T*VQ&   operator-=(T*VQ&, I);

   23For  every  triple  L,  VQ,  R), where L is an integral or enumeration
     type, VQ is either volatile or empty, and R  is  a  promoted  integral
     type, there exist candidate operator functions of the form

             VQ L&   operator%=(VQ L&, R);
             VQ L&   operator<<=(VQ L&, R);
             VQ L&   operator>>=(VQ L&, R);
             VQ L&   operator&=(VQ L&, R);
             VQ L&   operator^=(VQ L&, R);
             VQ L&   operator|=(VQ L&, R);  */

    case MODIFY_EXPR:
      switch (code2)
        {
        case PLUS_EXPR:
        case MINUS_EXPR:
          if (TYPE_PTROB_P (type1) && INTEGRAL_TYPE_P (type2))
            {
              type2 = ptrdiff_type_node;
              break;
            }
        case MULT_EXPR:
        case TRUNC_DIV_EXPR:
          if (ARITHMETIC_TYPE_P (type1) && ARITHMETIC_TYPE_P (type2))
            break;
          return;

        case TRUNC_MOD_EXPR:
        case BIT_AND_EXPR:
        case BIT_IOR_EXPR:
        case BIT_XOR_EXPR:
        case LSHIFT_EXPR:
        case RSHIFT_EXPR:
          if (INTEGRAL_TYPE_P (type1) && INTEGRAL_TYPE_P (type2))
            break;
          return;

        case NOP_EXPR:
          if (ARITHMETIC_TYPE_P (type1) && ARITHMETIC_TYPE_P (type2))
            break;
          if ((TYPE_PTRMEMFUNC_P (type1) && TYPE_PTRMEMFUNC_P (type2))
              || (TYPE_PTR_P (type1) && TYPE_PTR_P (type2))
              || (TYPE_PTRMEM_P (type1) && TYPE_PTRMEM_P (type2))
              || ((TYPE_PTRMEMFUNC_P (type1)
                   || TREE_CODE (type1) == POINTER_TYPE)
                  && null_ptr_cst_p (args[1])))
            {
              type2 = type1;
              break;
            }
          return;

        default:
          gcc_unreachable ();
        }
      type1 = build_reference_type (type1);
      break;

    case COND_EXPR:
      /* [over.built]

         For every pair of promoted arithmetic types L and R, there
         exist candidate operator functions of the form

         LR operator?(bool, L, R);

         where LR is the result of the usual arithmetic conversions
         between types L and R.

         For every type T, where T is a pointer or pointer-to-member
         type, there exist candidate operator functions of the form T
         operator?(bool, T, T);  */

      if (promoted_arithmetic_type_p (type1)
          && promoted_arithmetic_type_p (type2))
        /* That's OK.  */
        break;

      /* Otherwise, the types should be pointers.  */
      if (!(TYPE_PTR_P (type1) || TYPE_PTR_TO_MEMBER_P (type1))
          || !(TYPE_PTR_P (type2) || TYPE_PTR_TO_MEMBER_P (type2)))
        return;

      /* We don't check that the two types are the same; the logic
         below will actually create two candidates; one in which both
         parameter types are TYPE1, and one in which both parameter
         types are TYPE2.  */
      break;

    default:
      gcc_unreachable ();
    }

  /* If we're dealing with two pointer types or two enumeral types,
     we need candidates for both of them.  */
  if (type2 && !same_type_p (type1, type2)
      && TREE_CODE (type1) == TREE_CODE (type2)
      && (TREE_CODE (type1) == REFERENCE_TYPE
          || (TYPE_PTR_P (type1) && TYPE_PTR_P (type2))
          || (TYPE_PTRMEM_P (type1) && TYPE_PTRMEM_P (type2))
          || TYPE_PTRMEMFUNC_P (type1)
          || IS_AGGR_TYPE (type1)
          || TREE_CODE (type1) == ENUMERAL_TYPE))
    {
      build_builtin_candidate
        (candidates, fnname, type1, type1, args, argtypes, flags);
      build_builtin_candidate
        (candidates, fnname, type2, type2, args, argtypes, flags);
      return;
    }

  build_builtin_candidate
    (candidates, fnname, type1, type2, args, argtypes, flags);
}

tree
type_decays_to (tree type)
{
  if (TREE_CODE (type) == ARRAY_TYPE)
    return build_pointer_type (TREE_TYPE (type));
  if (TREE_CODE (type) == FUNCTION_TYPE)
    return build_pointer_type (type);
  return type;
}

/* There are three conditions of builtin candidates:

   1) bool-taking candidates.  These are the same regardless of the input.
   2) pointer-pair taking candidates.  These are generated for each type
      one of the input types converts to.
   3) arithmetic candidates.  According to the standard, we should generate
      all of these, but I'm trying not to...

   Here we generate a superset of the possible candidates for this particular
   case.  That is a subset of the full set the standard defines, plus some
   other cases which the standard disallows. add_builtin_candidate will
   filter out the invalid set.  */

static void
add_builtin_candidates (struct z_candidate **candidates, enum tree_code code,
                        enum tree_code code2, tree fnname, tree *args,
                        int flags)
{
  int ref1, i;
  int enum_p = 0;
  tree type, argtypes[3];
  /* TYPES[i] is the set of possible builtin-operator parameter types
     we will consider for the Ith argument.  These are represented as
     a TREE_LIST; the TREE_VALUE of each node is the potential
     parameter type.  */
  tree types[2];

  for (i = 0; i < 3; ++i)
    {
      if (args[i])
        argtypes[i]  = lvalue_type (args[i]);
      else
        argtypes[i] = NULL_TREE;
    }

  switch (code)
    {
/* 4 For every pair T, VQ), where T is an arithmetic or  enumeration  type,
     and  VQ  is  either  volatile or empty, there exist candidate operator
     functions of the form
                 VQ T&   operator++(VQ T&);  */

    case POSTINCREMENT_EXPR:
    case PREINCREMENT_EXPR:
    case POSTDECREMENT_EXPR:
    case PREDECREMENT_EXPR:
    case MODIFY_EXPR:
      ref1 = 1;
      break;

/* 24There also exist candidate operator functions of the form
             bool    operator!(bool);
             bool    operator&&(bool, bool);
             bool    operator||(bool, bool);  */

    case TRUTH_NOT_EXPR:
      build_builtin_candidate
        (candidates, fnname, boolean_type_node,
         NULL_TREE, args, argtypes, flags);
      return;

    case TRUTH_ORIF_EXPR:
    case TRUTH_ANDIF_EXPR:
      build_builtin_candidate
        (candidates, fnname, boolean_type_node,
         boolean_type_node, args, argtypes, flags);
      return;

    case ADDR_EXPR:
    case COMPOUND_EXPR:
    case COMPONENT_REF:
      return;

    case COND_EXPR:
    case EQ_EXPR:
    case NE_EXPR:
    case LT_EXPR:
    case LE_EXPR:
    case GT_EXPR:
    case GE_EXPR:
      enum_p = 1;
      /* Fall through.  */

    default:
      ref1 = 0;
    }

  types[0] = types[1] = NULL_TREE;

  for (i = 0; i < 2; ++i)
    {
      if (! args[i])
        ;
      else if (IS_AGGR_TYPE (argtypes[i]))
        {
          tree convs;

          if (i == 0 && code == MODIFY_EXPR && code2 == NOP_EXPR)
            return;

          convs = lookup_conversions (argtypes[i]);

          if (code == COND_EXPR)
            {
              if (real_lvalue_p (args[i]))
                types[i] = tree_cons
                  (NULL_TREE, build_reference_type (argtypes[i]), types[i]);

              types[i] = tree_cons
                (NULL_TREE, TYPE_MAIN_VARIANT (argtypes[i]), types[i]);
            }

          else if (! convs)
            return;

          for (; convs; convs = TREE_CHAIN (convs))
            {
              type = TREE_TYPE (TREE_TYPE (OVL_CURRENT (TREE_VALUE (convs))));

              if (i == 0 && ref1
                  && (TREE_CODE (type) != REFERENCE_TYPE
                      || CP_TYPE_CONST_P (TREE_TYPE (type))))
                continue;

              if (code == COND_EXPR && TREE_CODE (type) == REFERENCE_TYPE)
                types[i] = tree_cons (NULL_TREE, type, types[i]);

              type = non_reference (type);
              if (i != 0 || ! ref1)
                {
                  type = TYPE_MAIN_VARIANT (type_decays_to (type));
                  if (enum_p && TREE_CODE (type) == ENUMERAL_TYPE)
                    types[i] = tree_cons (NULL_TREE, type, types[i]);
                  if (INTEGRAL_TYPE_P (type))
                    type = type_promotes_to (type);
                }

              if (! value_member (type, types[i]))
                types[i] = tree_cons (NULL_TREE, type, types[i]);
            }
        }
      else
        {
          if (code == COND_EXPR && real_lvalue_p (args[i]))
            types[i] = tree_cons
              (NULL_TREE, build_reference_type (argtypes[i]), types[i]);
          type = non_reference (argtypes[i]);
          if (i != 0 || ! ref1)
            {
              type = TYPE_MAIN_VARIANT (type_decays_to (type));
              if (enum_p && TREE_CODE (type) == ENUMERAL_TYPE)
                types[i] = tree_cons (NULL_TREE, type, types[i]);
              if (INTEGRAL_TYPE_P (type))
                type = type_promotes_to (type);
            }
          types[i] = tree_cons (NULL_TREE, type, types[i]);
        }
    }

  /* Run through the possible parameter types of both arguments,
     creating candidates with those parameter types.  */
  for (; types[0]; types[0] = TREE_CHAIN (types[0]))
    {
      if (types[1])
        for (type = types[1]; type; type = TREE_CHAIN (type))
          add_builtin_candidate
            (candidates, code, code2, fnname, TREE_VALUE (types[0]),
             TREE_VALUE (type), args, argtypes, flags);
      else
        add_builtin_candidate
          (candidates, code, code2, fnname, TREE_VALUE (types[0]),
           NULL_TREE, args, argtypes, flags);
    }
}


/* If TMPL can be successfully instantiated as indicated by
   EXPLICIT_TARGS and ARGLIST, adds the instantiation to CANDIDATES.

   TMPL is the template.  EXPLICIT_TARGS are any explicit template
   arguments.  ARGLIST is the arguments provided at the call-site.
   The RETURN_TYPE is the desired type for conversion operators.  If
   OBJ is NULL_TREE, FLAGS and CTYPE are as for add_function_candidate.
   If an OBJ is supplied, FLAGS and CTYPE are ignored, and OBJ is as for
   add_conv_candidate.  */

static struct z_candidate*
add_template_candidate_real (struct z_candidate **candidates, tree tmpl,
                             tree ctype, tree explicit_targs, tree arglist,
                             tree return_type, tree access_path,
                             tree conversion_path, int flags, tree obj,
                             unification_kind_t strict)
{
  int ntparms = DECL_NTPARMS (tmpl);
  tree targs = make_tree_vec (ntparms);
  tree args_without_in_chrg = arglist;
  struct z_candidate *cand;
  int i;
  tree fn;

  /* We don't do deduction on the in-charge parameter, the VTT
     parameter or 'this'.  */
  if (DECL_NONSTATIC_MEMBER_FUNCTION_P (tmpl))
    args_without_in_chrg = TREE_CHAIN (args_without_in_chrg);

  if ((DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (tmpl)
       || DECL_BASE_CONSTRUCTOR_P (tmpl))
      && CLASSTYPE_VBASECLASSES (DECL_CONTEXT (tmpl)))
    args_without_in_chrg = TREE_CHAIN (args_without_in_chrg);

  i = fn_type_unification (tmpl, explicit_targs, targs,
                           args_without_in_chrg,
                           return_type, strict, flags);

  if (i != 0)
    return NULL;

  fn = instantiate_template (tmpl, targs, tf_none);
  if (fn == error_mark_node)
    return NULL;

  /* In [class.copy]:

       A member function template is never instantiated to perform the
       copy of a class object to an object of its class type.

     It's a little unclear what this means; the standard explicitly
     does allow a template to be used to copy a class.  For example,
     in:

       struct A {
         A(A&);
         template <class T> A(const T&);
       };
       const A f ();
       void g () { A a (f ()); }

     the member template will be used to make the copy.  The section
     quoted above appears in the paragraph that forbids constructors
     whose only parameter is (a possibly cv-qualified variant of) the
     class type, and a logical interpretation is that the intent was
     to forbid the instantiation of member templates which would then
     have that form.  */
  if (DECL_CONSTRUCTOR_P (fn) && list_length (arglist) == 2)
    {
      tree arg_types = FUNCTION_FIRST_USER_PARMTYPE (fn);
      if (arg_types && same_type_p (TYPE_MAIN_VARIANT (TREE_VALUE (arg_types)),
                                    ctype))
        return NULL;
    }

  if (obj != NULL_TREE)
    /* Aha, this is a conversion function.  */
    cand = add_conv_candidate (candidates, fn, obj, access_path,
                               conversion_path, arglist);
  else
    cand = add_function_candidate (candidates, fn, ctype,
                                   arglist, access_path,
                                   conversion_path, flags);
  if (DECL_TI_TEMPLATE (fn) != tmpl)
    /* This situation can occur if a member template of a template
       class is specialized.  Then, instantiate_template might return
       an instantiation of the specialization, in which case the
       DECL_TI_TEMPLATE field will point at the original
       specialization.  For example:

         template <class T> struct S { template <class U> void f(U);
                                       template <> void f(int) {}; };
         S<double> sd;
         sd.f(3);

       Here, TMPL will be template <class U> S<double>::f(U).
       And, instantiate template will give us the specialization
       template <> S<double>::f(int).  But, the DECL_TI_TEMPLATE field
       for this will point at template <class T> template <> S<T>::f(int),
       so that we can find the definition.  For the purposes of
       overload resolution, however, we want the original TMPL.  */
    cand->template_decl = tree_cons (tmpl, targs, NULL_TREE);
  else
    cand->template_decl = DECL_TEMPLATE_INFO (fn);

  return cand;
}


static struct z_candidate *
add_template_candidate (struct z_candidate **candidates, tree tmpl, tree ctype,
                        tree explicit_targs, tree arglist, tree return_type,
                        tree access_path, tree conversion_path, int flags,
                        unification_kind_t strict)
{
  return
    add_template_candidate_real (candidates, tmpl, ctype,
                                 explicit_targs, arglist, return_type,
                                 access_path, conversion_path,
                                 flags, NULL_TREE, strict);
}


static struct z_candidate *
add_template_conv_candidate (struct z_candidate **candidates, tree tmpl,
                             tree obj, tree arglist, tree return_type,
                             tree access_path, tree conversion_path)
{
  return
    add_template_candidate_real (candidates, tmpl, NULL_TREE, NULL_TREE,
                                 arglist, return_type, access_path,
                                 conversion_path, 0, obj, DEDUCE_CONV);
}

/* The CANDS are the set of candidates that were considered for
   overload resolution.  Return the set of viable candidates.  If none
   of the candidates were viable, set *ANY_VIABLE_P to true.  STRICT_P
   is true if a candidate should be considered viable only if it is
   strictly viable.  */

static struct z_candidate*
splice_viable (struct z_candidate *cands,
               bool strict_p,
               bool *any_viable_p)
{
  struct z_candidate *viable;
  struct z_candidate **last_viable;
  struct z_candidate **cand;

  viable = NULL;
  last_viable = &viable;
  *any_viable_p = false;

  cand = &cands;
  while (*cand)
    {
      struct z_candidate *c = *cand;
      if (strict_p ? c->viable == 1 : c->viable)
        {
          *last_viable = c;
          *cand = c->next;
          c->next = NULL;
          last_viable = &c->next;
          *any_viable_p = true;
        }
      else
        cand = &c->next;
    }

  return viable ? viable : cands;
}

static bool
any_strictly_viable (struct z_candidate *cands)
{
  for (; cands; cands = cands->next)
    if (cands->viable == 1)
      return true;
  return false;
}

/* OBJ is being used in an expression like "OBJ.f (...)".  In other
   words, it is about to become the "this" pointer for a member
   function call.  Take the address of the object.  */

static tree
build_this (tree obj)
{
  /* In a template, we are only concerned about the type of the
     expression, so we can take a shortcut.  */
  if (processing_template_decl)
    return build_address (obj);

  return build_unary_op (ADDR_EXPR, obj, 0);
}

/* Returns true iff functions are equivalent. Equivalent functions are
   not '==' only if one is a function-local extern function or if
   both are extern "C".  */

static inline int
equal_functions (tree fn1, tree fn2)
{
  if (DECL_LOCAL_FUNCTION_P (fn1) || DECL_LOCAL_FUNCTION_P (fn2)
      || DECL_EXTERN_C_FUNCTION_P (fn1))
    return decls_match (fn1, fn2);
  return fn1 == fn2;
}

/* Print information about one overload candidate CANDIDATE.  MSGSTR
   is the text to print before the candidate itself.

   NOTE: Unlike most diagnostic functions in GCC, MSGSTR is expected
   to have been run through gettext by the caller.  This wart makes
   life simpler in print_z_candidates and for the translators.  */

static void
print_z_candidate (const char *msgstr, struct z_candidate *candidate)
{
  if (TREE_CODE (candidate->fn) == IDENTIFIER_NODE)
    {
      if (candidate->num_convs == 3)
        inform ("%s %D(%T, %T, %T) <built-in>", msgstr, candidate->fn,
                candidate->convs[0]->type,
                candidate->convs[1]->type,
                candidate->convs[2]->type);
      else if (candidate->num_convs == 2)
        inform ("%s %D(%T, %T) <built-in>", msgstr, candidate->fn,
                candidate->convs[0]->type,
                candidate->convs[1]->type);
      else
        inform ("%s %D(%T) <built-in>", msgstr, candidate->fn,
                candidate->convs[0]->type);
    }
  else if (TYPE_P (candidate->fn))
    inform ("%s %T <conversion>", msgstr, candidate->fn);
  else if (candidate->viable == -1)
    inform ("%s %+#D <near match>", msgstr, candidate->fn);
  else
    inform ("%s %+#D", msgstr, candidate->fn);
}

static void
print_z_candidates (struct z_candidate *candidates)
{
  const char *str;
  struct z_candidate *cand1;
  struct z_candidate **cand2;

  /* There may be duplicates in the set of candidates.  We put off
     checking this condition as long as possible, since we have no way
     to eliminate duplicates from a set of functions in less than n^2
     time.  Now we are about to emit an error message, so it is more
     permissible to go slowly.  */
  for (cand1 = candidates; cand1; cand1 = cand1->next)
    {
      tree fn = cand1->fn;
      /* Skip builtin candidates and conversion functions.  */
      if (TREE_CODE (fn) != FUNCTION_DECL)
        continue;
      cand2 = &cand1->next;
      while (*cand2)
        {
          if (TREE_CODE ((*cand2)->fn) == FUNCTION_DECL
              && equal_functions (fn, (*cand2)->fn))
            *cand2 = (*cand2)->next;
          else
            cand2 = &(*cand2)->next;
        }
    }

  if (!candidates)
    return;

  str = _("candidates are:");
  print_z_candidate (str, candidates);
  if (candidates->next)
    {
      /* Indent successive candidates by the width of the translation
         of the above string.  */
      size_t len = gcc_gettext_width (str) + 1;
      char *spaces = (char *) alloca (len);
      memset (spaces, ' ', len-1);
      spaces[len - 1] = '\0';

      candidates = candidates->next;
      do
        {
          print_z_candidate (spaces, candidates);
          candidates = candidates->next;
        }
      while (candidates);
    }
}

/* USER_SEQ is a user-defined conversion sequence, beginning with a
   USER_CONV.  STD_SEQ is the standard conversion sequence applied to
   the result of the conversion function to convert it to the final
   desired type.  Merge the two sequences into a single sequence,
   and return the merged sequence.  */

static conversion *
merge_conversion_sequences (conversion *user_seq, conversion *std_seq)
{
  conversion **t;

  gcc_assert (user_seq->kind == ck_user);

  /* Find the end of the second conversion sequence.  */
  t = &(std_seq);
  while ((*t)->kind != ck_identity)
    t = &((*t)->u.next);

  /* Replace the identity conversion with the user conversion
     sequence.  */
  *t = user_seq;

  /* The entire sequence is a user-conversion sequence.  */
  std_seq->user_conv_p = true;

  return std_seq;
}

/* Returns the best overload candidate to perform the requested
   conversion.  This function is used for three the overloading situations
   described in [over.match.copy], [over.match.conv], and [over.match.ref].
   If TOTYPE is a REFERENCE_TYPE, we're trying to find an lvalue binding as
   per [dcl.init.ref], so we ignore temporary bindings.  */

static struct z_candidate *
build_user_type_conversion_1 (tree totype, tree expr, int flags)
{
  struct z_candidate *candidates, *cand;
  tree fromtype = TREE_TYPE (expr);
  tree ctors = NULL_TREE;
  tree conv_fns = NULL_TREE;
  conversion *conv = NULL;
  tree args = NULL_TREE;
  bool any_viable_p;

  /* We represent conversion within a hierarchy using RVALUE_CONV and
     BASE_CONV, as specified by [over.best.ics]; these become plain
     constructor calls, as specified in [dcl.init].  */
  gcc_assert (!IS_AGGR_TYPE (fromtype) || !IS_AGGR_TYPE (totype)
              || !DERIVED_FROM_P (totype, fromtype));

  if (IS_AGGR_TYPE (totype))
    ctors = lookup_fnfields (totype, complete_ctor_identifier, 0);

  if (IS_AGGR_TYPE (fromtype))
    conv_fns = lookup_conversions (fromtype);

  candidates = 0;
  flags |= LOOKUP_NO_CONVERSION;

  if (ctors)
    {
      tree t;

      ctors = BASELINK_FUNCTIONS (ctors);

      t = build_int_cst (build_pointer_type (totype), 0);
      args = build_tree_list (NULL_TREE, expr);
      /* We should never try to call the abstract or base constructor
         from here.  */
      gcc_assert (!DECL_HAS_IN_CHARGE_PARM_P (OVL_CURRENT (ctors))
                  && !DECL_HAS_VTT_PARM_P (OVL_CURRENT (ctors)));
      args = tree_cons (NULL_TREE, t, args);
    }
  for (; ctors; ctors = OVL_NEXT (ctors))
    {
      tree ctor = OVL_CURRENT (ctors);
      if (DECL_NONCONVERTING_P (ctor))
        continue;

      if (TREE_CODE (ctor) == TEMPLATE_DECL)
        cand = add_template_candidate (&candidates, ctor, totype,
                                       NULL_TREE, args, NULL_TREE,
                                       TYPE_BINFO (totype),
                                       TYPE_BINFO (totype),
                                       flags,
                                       DEDUCE_CALL);
      else
        cand = add_function_candidate (&candidates, ctor, totype,
                                       args, TYPE_BINFO (totype),
                                       TYPE_BINFO (totype),
                                       flags);

      if (cand)
        cand->second_conv = build_identity_conv (totype, NULL_TREE);
    }

  if (conv_fns)
    args = build_tree_list (NULL_TREE, build_this (expr));

  for (; conv_fns; conv_fns = TREE_CHAIN (conv_fns))
    {
      tree fns;
      tree conversion_path = TREE_PURPOSE (conv_fns);
      int convflags = LOOKUP_NO_CONVERSION;

      /* If we are called to convert to a reference type, we are trying to
         find an lvalue binding, so don't even consider temporaries.  If
         we don't find an lvalue binding, the caller will try again to
         look for a temporary binding.  */
      if (TREE_CODE (totype) == REFERENCE_TYPE)
        convflags |= LOOKUP_NO_TEMP_BIND;

      for (fns = TREE_VALUE (conv_fns); fns; fns = OVL_NEXT (fns))
        {
          tree fn = OVL_CURRENT (fns);

          /* [over.match.funcs] For conversion functions, the function
             is considered to be a member of the class of the implicit
             object argument for the purpose of defining the type of
             the implicit object parameter.

             So we pass fromtype as CTYPE to add_*_candidate.  */

          if (TREE_CODE (fn) == TEMPLATE_DECL)
            cand = add_template_candidate (&candidates, fn, fromtype,
                                           NULL_TREE,
                                           args, totype,
                                           TYPE_BINFO (fromtype),
                                           conversion_path,
                                           flags,
                                           DEDUCE_CONV);
          else
            cand = add_function_candidate (&candidates, fn, fromtype,
                                           args,
                                           TYPE_BINFO (fromtype),
                                           conversion_path,
                                           flags);

          if (cand)
            {
              conversion *ics
                = implicit_conversion (totype,
                                       TREE_TYPE (TREE_TYPE (cand->fn)),
                                       0,
                                       /*c_cast_p=*/false, convflags);

              cand->second_conv = ics;

              if (!ics)
                cand->viable = 0;
              else if (candidates->viable == 1 && ics->bad_p)
                cand->viable = -1;
            }
        }
    }

  candidates = splice_viable (candidates, pedantic, &any_viable_p);
  if (!any_viable_p)
    return NULL;

  cand = tourney (candidates);
  if (cand == 0)
    {
      if (flags & LOOKUP_COMPLAIN)
        {
          error ("conversion from %qT to %qT is ambiguous",
                    fromtype, totype);
          print_z_candidates (candidates);
        }

      cand = candidates;        /* any one will do */
      cand->second_conv = build_ambiguous_conv (totype, expr);
      cand->second_conv->user_conv_p = true;
      if (!any_strictly_viable (candidates))
        cand->second_conv->bad_p = true;
      /* If there are viable candidates, don't set ICS_BAD_FLAG; an
         ambiguous conversion is no worse than another user-defined
         conversion.  */

      return cand;
    }

  /* Build the user conversion sequence.  */
  conv = build_conv
    (ck_user,
     (DECL_CONSTRUCTOR_P (cand->fn)
      ? totype : non_reference (TREE_TYPE (TREE_TYPE (cand->fn)))),
     build_identity_conv (TREE_TYPE (expr), expr));
  conv->cand = cand;

  /* Combine it with the second conversion sequence.  */
  cand->second_conv = merge_conversion_sequences (conv,
                                                  cand->second_conv);

  if (cand->viable == -1)
    cand->second_conv->bad_p = true;

  return cand;
}

tree
build_user_type_conversion (tree totype, tree expr, int flags)
{
  struct z_candidate *cand
    = build_user_type_conversion_1 (totype, expr, flags);

  if (cand)
    {
      if (cand->second_conv->kind == ck_ambig)
        return error_mark_node;
      expr = convert_like (cand->second_conv, expr);
      return convert_from_reference (expr);
    }
  return NULL_TREE;
}

/* Do any initial processing on the arguments to a function call.  */

static tree
resolve_args (tree args)
{
  tree t;
  for (t = args; t; t = TREE_CHAIN (t))
    {
      tree arg = TREE_VALUE (t);

      if (error_operand_p (arg))
        return error_mark_node;
      else if (VOID_TYPE_P (TREE_TYPE (arg)))
        {
          error ("invalid use of void expression");
          return error_mark_node;
        }
      else if (invalid_nonstatic_memfn_p (arg))
        return error_mark_node;
    }
  return args;
}

/* Perform overload resolution on FN, which is called with the ARGS.

   Return the candidate function selected by overload resolution, or
   NULL if the event that overload resolution failed.  In the case
   that overload resolution fails, *CANDIDATES will be the set of
   candidates considered, and ANY_VIABLE_P will be set to true or
   false to indicate whether or not any of the candidates were
   viable.

   The ARGS should already have gone through RESOLVE_ARGS before this
   function is called.  */

static struct z_candidate *
perform_overload_resolution (tree fn,
                             tree args,
                             struct z_candidate **candidates,
                             bool *any_viable_p)
{
  struct z_candidate *cand;
  tree explicit_targs = NULL_TREE;
  int template_only = 0;

  *candidates = NULL;
  *any_viable_p = true;

  /* Check FN and ARGS.  */
  gcc_assert (TREE_CODE (fn) == FUNCTION_DECL
              || TREE_CODE (fn) == TEMPLATE_DECL
              || TREE_CODE (fn) == OVERLOAD
              || TREE_CODE (fn) == TEMPLATE_ID_EXPR);
  gcc_assert (!args || TREE_CODE (args) == TREE_LIST);

  if (TREE_CODE (fn) == TEMPLATE_ID_EXPR)
    {
      explicit_targs = TREE_OPERAND (fn, 1);
      fn = TREE_OPERAND (fn, 0);
      template_only = 1;
    }

  /* Add the various candidate functions.  */
  add_candidates (fn, args, explicit_targs, template_only,
                  /*conversion_path=*/NULL_TREE,
                  /*access_path=*/NULL_TREE,
                  LOOKUP_NORMAL,
                  candidates);

  *candidates = splice_viable (*candidates, pedantic, any_viable_p);
  if (!*any_viable_p)
    return NULL;

  cand = tourney (*candidates);
  return cand;
}

/* Return an expression for a call to FN (a namespace-scope function,
   or a static member function) with the ARGS.  */

tree
build_new_function_call (tree fn, tree args, bool koenig_p)
{
  struct z_candidate *candidates, *cand;
  bool any_viable_p;
  void *p;
  tree result;

  args = resolve_args (args);
  if (args == error_mark_node)
    return error_mark_node;

  /* If this function was found without using argument dependent
     lookup, then we want to ignore any undeclared friend
     functions.  */
  if (!koenig_p)
    {
      tree orig_fn = fn;

      fn = remove_hidden_names (fn);
      if (!fn)
        {
          error ("no matching function for call to %<%D(%A)%>",
                 DECL_NAME (OVL_CURRENT (orig_fn)), args);
          return error_mark_node;
        }
    }

  /* Get the high-water mark for the CONVERSION_OBSTACK.  */
  p = conversion_obstack_alloc (0);

  cand = perform_overload_resolution (fn, args, &candidates, &any_viable_p);

  if (!cand)
    {
      if (!any_viable_p && candidates && ! candidates->next)
        return build_function_call (candidates->fn, args);
      if (TREE_CODE (fn) == TEMPLATE_ID_EXPR)
        fn = TREE_OPERAND (fn, 0);
      if (!any_viable_p)
        error ("no matching function for call to %<%D(%A)%>",
               DECL_NAME (OVL_CURRENT (fn)), args);
      else
        error ("call of overloaded %<%D(%A)%> is ambiguous",
               DECL_NAME (OVL_CURRENT (fn)), args);
      if (candidates)
        print_z_candidates (candidates);
      result = error_mark_node;
    }
  else
    result = build_over_call (cand, LOOKUP_NORMAL);

  /* Free all the conversions we allocated.  */
  obstack_free (&conversion_obstack, p);

  return result;
}

/* Build a call to a global operator new.  FNNAME is the name of the
   operator (either "operator new" or "operator new[]") and ARGS are
   the arguments provided.  *SIZE points to the total number of bytes
   required by the allocation, and is updated if that is changed here.
   *COOKIE_SIZE is non-NULL if a cookie should be used.  If this
   function determines that no cookie should be used, after all,
   *COOKIE_SIZE is set to NULL_TREE.  If FN is non-NULL, it will be
   set, upon return, to the allocation function called.  */

tree
build_operator_new_call (tree fnname, tree args,
                         tree *size, tree *cookie_size,
                         tree *fn)
{
  tree fns;
  struct z_candidate *candidates;
  struct z_candidate *cand;
  bool any_viable_p;

  if (fn)
    *fn = NULL_TREE;
  args = tree_cons (NULL_TREE, *size, args);
  args = resolve_args (args);
  if (args == error_mark_node)
    return args;

  /* Based on:

       [expr.new]

       If this lookup fails to find the name, or if the allocated type
       is not a class type, the allocation function's name is looked
       up in the global scope.

     we disregard block-scope declarations of "operator new".  */
  fns = lookup_function_nonclass (fnname, args, /*block_p=*/false);

  /* Figure out what function is being called.  */
  cand = perform_overload_resolution (fns, args, &candidates, &any_viable_p);

  /* If no suitable function could be found, issue an error message
     and give up.  */
  if (!cand)
    {
      if (!any_viable_p)
        error ("no matching function for call to %<%D(%A)%>",
               DECL_NAME (OVL_CURRENT (fns)), args);
      else
        error ("call of overloaded %<%D(%A)%> is ambiguous",
               DECL_NAME (OVL_CURRENT (fns)), args);
      if (candidates)
        print_z_candidates (candidates);
      return error_mark_node;
    }

   /* If a cookie is required, add some extra space.  Whether
      or not a cookie is required cannot be determined until
      after we know which function was called.  */
   if (*cookie_size)
     {
       bool use_cookie = true;
       if (!abi_version_at_least (2))
         {
           tree placement = TREE_CHAIN (args);
           /* In G++ 3.2, the check was implemented incorrectly; it
              looked at the placement expression, rather than the
              type of the function.  */
           if (placement && !TREE_CHAIN (placement)
               && same_type_p (TREE_TYPE (TREE_VALUE (placement)),
                               ptr_type_node))
             use_cookie = false;
         }
       else
         {
           tree arg_types;

           arg_types = TYPE_ARG_TYPES (TREE_TYPE (cand->fn));
           /* Skip the size_t parameter.  */
           arg_types = TREE_CHAIN (arg_types);
           /* Check the remaining parameters (if any).  */
           if (arg_types
               && TREE_CHAIN (arg_types) == void_list_node
               && same_type_p (TREE_VALUE (arg_types),
                               ptr_type_node))
             use_cookie = false;
         }
       /* If we need a cookie, adjust the number of bytes allocated.  */
       if (use_cookie)
         {
           /* Update the total size.  */
           *size = size_binop (PLUS_EXPR, *size, *cookie_size);
           /* Update the argument list to reflect the adjusted size.  */
           TREE_VALUE (args) = *size;
         }
       else
         *cookie_size = NULL_TREE;
     }

   /* Tell our caller which function we decided to call.  */
   if (fn)
     *fn = cand->fn;

   /* Build the CALL_EXPR.  */
   return build_over_call (cand, LOOKUP_NORMAL);
}

static tree
build_object_call (tree obj, tree args)
{
  struct z_candidate *candidates = 0, *cand;
  tree fns, convs, mem_args = NULL_TREE;
  tree type = TREE_TYPE (obj);
  bool any_viable_p;
  tree result = NULL_TREE;
  void *p;

  if (TYPE_PTRMEMFUNC_P (type))
    {
      /* It's no good looking for an overloaded operator() on a
         pointer-to-member-function.  */
      error ("pointer-to-member function %E cannot be called without an object; consider using .* or ->*", obj);
      return error_mark_node;
    }

  if (TYPE_BINFO (type))
    {
      fns = lookup_fnfields (TYPE_BINFO (type), ansi_opname (CALL_EXPR), 1);
      if (fns == error_mark_node)
        return error_mark_node;
    }
  else
    fns = NULL_TREE;

  args = resolve_args (args);

  if (args == error_mark_node)
    return error_mark_node;

  /* Get the high-water mark for the CONVERSION_OBSTACK.  */
  p = conversion_obstack_alloc (0);

  if (fns)
    {
      tree base = BINFO_TYPE (BASELINK_BINFO (fns));
      mem_args = tree_cons (NULL_TREE, build_this (obj), args);

      for (fns = BASELINK_FUNCTIONS (fns); fns; fns = OVL_NEXT (fns))
        {
          tree fn = OVL_CURRENT (fns);
          if (TREE_CODE (fn) == TEMPLATE_DECL)
            add_template_candidate (&candidates, fn, base, NULL_TREE,
                                    mem_args, NULL_TREE,
                                    TYPE_BINFO (type),
                                    TYPE_BINFO (type),
                                    LOOKUP_NORMAL, DEDUCE_CALL);
          else
            add_function_candidate
              (&candidates, fn, base, mem_args, TYPE_BINFO (type),
               TYPE_BINFO (type), LOOKUP_NORMAL);
        }
    }

  convs = lookup_conversions (type);

  for (; convs; convs = TREE_CHAIN (convs))
    {
      tree fns = TREE_VALUE (convs);
      tree totype = TREE_TYPE (TREE_TYPE (OVL_CURRENT (fns)));

      if ((TREE_CODE (totype) == POINTER_TYPE
           && TREE_CODE (TREE_TYPE (totype)) == FUNCTION_TYPE)
          || (TREE_CODE (totype) == REFERENCE_TYPE
              && TREE_CODE (TREE_TYPE (totype)) == FUNCTION_TYPE)
          || (TREE_CODE (totype) == REFERENCE_TYPE
              && TREE_CODE (TREE_TYPE (totype)) == POINTER_TYPE
              && TREE_CODE (TREE_TYPE (TREE_TYPE (totype))) == FUNCTION_TYPE))
        for (; fns; fns = OVL_NEXT (fns))
          {
            tree fn = OVL_CURRENT (fns);
            if (TREE_CODE (fn) == TEMPLATE_DECL)
              add_template_conv_candidate
                (&candidates, fn, obj, args, totype,
                 /*access_path=*/NULL_TREE,
                 /*conversion_path=*/NULL_TREE);
            else
              add_conv_candidate (&candidates, fn, obj, args,
                                  /*conversion_path=*/NULL_TREE,
                                  /*access_path=*/NULL_TREE);
          }
    }

  candidates = splice_viable (candidates, pedantic, &any_viable_p);
  if (!any_viable_p)
    {
      error ("no match for call to %<(%T) (%A)%>", TREE_TYPE (obj), args);
      print_z_candidates (candidates);
      result = error_mark_node;
    }
  else
    {
      cand = tourney (candidates);
      if (cand == 0)
        {
          error ("call of %<(%T) (%A)%> is ambiguous", TREE_TYPE (obj), args);
          print_z_candidates (candidates);
          result = error_mark_node;
        }
      /* Since cand->fn will be a type, not a function, for a conversion
         function, we must be careful not to unconditionally look at
         DECL_NAME here.  */
      else if (TREE_CODE (cand->fn) == FUNCTION_DECL
               && DECL_OVERLOADED_OPERATOR_P (cand->fn) == CALL_EXPR)
        result = build_over_call (cand, LOOKUP_NORMAL);
      else
        {
          obj = convert_like_with_context (cand->convs[0], obj, cand->fn, -1);
          obj = convert_from_reference (obj);
          result = build_function_call (obj, args);
        }
    }

  /* Free all the conversions we allocated.  */
  obstack_free (&conversion_obstack, p);

  return result;
}

static void
op_error (enum tree_code code, enum tree_code code2,
          tree arg1, tree arg2, tree arg3, const char *problem)
{
  const char *opname;

  if (code == MODIFY_EXPR)
    opname = assignment_operator_name_info[code2].name;
  else
    opname = operator_name_info[code].name;

  switch (code)
    {
    case COND_EXPR:
      error ("%s for ternary %<operator?:%> in %<%E ? %E : %E%>",
             problem, arg1, arg2, arg3);
      break;

    case POSTINCREMENT_EXPR:
    case POSTDECREMENT_EXPR:
      error ("%s for %<operator%s%> in %<%E%s%>", problem, opname, arg1, opname);
      break;

    case ARRAY_REF:
      error ("%s for %<operator[]%> in %<%E[%E]%>", problem, arg1, arg2);
      break;

    case REALPART_EXPR:
    case IMAGPART_EXPR:
      error ("%s for %qs in %<%s %E%>", problem, opname, opname, arg1);
      break;

    default:
      if (arg2)
        error ("%s for %<operator%s%> in %<%E %s %E%>",
               problem, opname, arg1, opname, arg2);
      else
        error ("%s for %<operator%s%> in %<%s%E%>",
               problem, opname, opname, arg1);
      break;
    }
}

/* Return the implicit conversion sequence that could be used to
   convert E1 to E2 in [expr.cond].  */

static conversion *
conditional_conversion (tree e1, tree e2)
{
  tree t1 = non_reference (TREE_TYPE (e1));
  tree t2 = non_reference (TREE_TYPE (e2));
  conversion *conv;
  bool good_base;

  /* [expr.cond]

     If E2 is an lvalue: E1 can be converted to match E2 if E1 can be
     implicitly converted (clause _conv_) to the type "reference to
     T2", subject to the constraint that in the conversion the
     reference must bind directly (_dcl.init.ref_) to E1.  */
  if (real_lvalue_p (e2))
    {
      conv = implicit_conversion (build_reference_type (t2),
                                  t1,
                                  e1,
                                  /*c_cast_p=*/false,
                                  LOOKUP_NO_TEMP_BIND);
      if (conv)
        return conv;
    }

  /* [expr.cond]

     If E1 and E2 have class type, and the underlying class types are
     the same or one is a base class of the other: E1 can be converted
     to match E2 if the class of T2 is the same type as, or a base
     class of, the class of T1, and the cv-qualification of T2 is the
     same cv-qualification as, or a greater cv-qualification than, the
     cv-qualification of T1.  If the conversion is applied, E1 is
     changed to an rvalue of type T2 that still refers to the original
     source class object (or the appropriate subobject thereof).  */
  if (CLASS_TYPE_P (t1) && CLASS_TYPE_P (t2)
      && ((good_base = DERIVED_FROM_P (t2, t1)) || DERIVED_FROM_P (t1, t2)))
    {
      if (good_base && at_least_as_qualified_p (t2, t1))
        {
          conv = build_identity_conv (t1, e1);
          if (!same_type_p (TYPE_MAIN_VARIANT (t1),
                            TYPE_MAIN_VARIANT (t2)))
            conv = build_conv (ck_base, t2, conv);
          else
            conv = build_conv (ck_rvalue, t2, conv);
          return conv;
        }
      else
        return NULL;
    }
  else
    /* [expr.cond]

       Otherwise: E1 can be converted to match E2 if E1 can be implicitly
       converted to the type that expression E2 would have if E2 were
       converted to an rvalue (or the type it has, if E2 is an rvalue).  */
    return implicit_conversion (t2, t1, e1, /*c_cast_p=*/false,
                                LOOKUP_NORMAL);
}

/* Implement [expr.cond].  ARG1, ARG2, and ARG3 are the three
   arguments to the conditional expression.  */

tree
build_conditional_expr (tree arg1, tree arg2, tree arg3)
{
  tree arg2_type;
  tree arg3_type;
  tree result = NULL_TREE;
  tree result_type = NULL_TREE;
  bool lvalue_p = true;
  struct z_candidate *candidates = 0;
  struct z_candidate *cand;
  void *p;

  /* As a G++ extension, the second argument to the conditional can be
     omitted.  (So that `a ? : c' is roughly equivalent to `a ? a :
     c'.)  If the second operand is omitted, make sure it is
     calculated only once.  */
  if (!arg2)
    {
      if (pedantic)
        pedwarn ("ISO C++ forbids omitting the middle term of a ?: expression");

      /* Make sure that lvalues remain lvalues.  See g++.oliva/ext1.C.  */
      if (real_lvalue_p (arg1))
        arg2 = arg1 = stabilize_reference (arg1);
      else
        arg2 = arg1 = save_expr (arg1);
    }

  /* [expr.cond]

     The first expr ession is implicitly converted to bool (clause
     _conv_).  */
  arg1 = perform_implicit_conversion (boolean_type_node, arg1);

  /* If something has already gone wrong, just pass that fact up the
     tree.  */
  if (error_operand_p (arg1)
      || error_operand_p (arg2)
      || error_operand_p (arg3))
    return error_mark_node;

  /* [expr.cond]

     If either the second or the third operand has type (possibly
     cv-qualified) void, then the lvalue-to-rvalue (_conv.lval_),
     array-to-pointer (_conv.array_), and function-to-pointer
     (_conv.func_) standard conversions are performed on the second
     and third operands.  */
  arg2_type = unlowered_expr_type (arg2);
  arg3_type = unlowered_expr_type (arg3);
  if (VOID_TYPE_P (arg2_type) || VOID_TYPE_P (arg3_type))
    {
      /* Do the conversions.  We don't these for `void' type arguments
         since it can't have any effect and since decay_conversion
         does not handle that case gracefully.  */
      if (!VOID_TYPE_P (arg2_type))
        arg2 = decay_conversion (arg2);
      if (!VOID_TYPE_P (arg3_type))
        arg3 = decay_conversion (arg3);
      arg2_type = TREE_TYPE (arg2);
      arg3_type = TREE_TYPE (arg3);

      /* [expr.cond]

         One of the following shall hold:

         --The second or the third operand (but not both) is a
           throw-expression (_except.throw_); the result is of the
           type of the other and is an rvalue.

         --Both the second and the third operands have type void; the
           result is of type void and is an rvalue.

         We must avoid calling force_rvalue for expressions of type
         "void" because it will complain that their value is being
         used.  */
      if (TREE_CODE (arg2) == THROW_EXPR
          && TREE_CODE (arg3) != THROW_EXPR)
        {
          if (!VOID_TYPE_P (arg3_type))
            arg3 = force_rvalue (arg3);
          arg3_type = TREE_TYPE (arg3);
          result_type = arg3_type;
        }
      else if (TREE_CODE (arg2) != THROW_EXPR
               && TREE_CODE (arg3) == THROW_EXPR)
        {
          if (!VOID_TYPE_P (arg2_type))
            arg2 = force_rvalue (arg2);
          arg2_type = TREE_TYPE (arg2);
          result_type = arg2_type;
        }
      else if (VOID_TYPE_P (arg2_type) && VOID_TYPE_P (arg3_type))
        result_type = void_type_node;
      else
        {
          if (VOID_TYPE_P (arg2_type))
            error ("second operand to the conditional operator "
                   "is of type %<void%>, "
                   "but the third operand is neither a throw-expression "
                   "nor of type %<void%>");
          else
            error ("third operand to the conditional operator "
                   "is of type %<void%>, "
                   "but the second operand is neither a throw-expression "
                   "nor of type %<void%>");
          return error_mark_node;
        }

      lvalue_p = false;
      goto valid_operands;
    }
  /* [expr.cond]

     Otherwise, if the second and third operand have different types,
     and either has (possibly cv-qualified) class type, an attempt is
     made to convert each of those operands to the type of the other.  */
  else if (!same_type_p (arg2_type, arg3_type)
           && (CLASS_TYPE_P (arg2_type) || CLASS_TYPE_P (arg3_type)))
    {
      conversion *conv2;
      conversion *conv3;

      /* Get the high-water mark for the CONVERSION_OBSTACK.  */
      p = conversion_obstack_alloc (0);

      conv2 = conditional_conversion (arg2, arg3);
      conv3 = conditional_conversion (arg3, arg2);

      /* [expr.cond]

         If both can be converted, or one can be converted but the
         conversion is ambiguous, the program is ill-formed.  If
         neither can be converted, the operands are left unchanged and
         further checking is performed as described below.  If exactly
         one conversion is possible, that conversion is applied to the
         chosen operand and the converted operand is used in place of
         the original operand for the remainder of this section.  */
      if ((conv2 && !conv2->bad_p
           && conv3 && !conv3->bad_p)
          || (conv2 && conv2->kind == ck_ambig)
          || (conv3 && conv3->kind == ck_ambig))
        {
          error ("operands to ?: have different types %qT and %qT",
                 arg2_type, arg3_type);
          result = error_mark_node;
        }
      else if (conv2 && (!conv2->bad_p || !conv3))
        {
          arg2 = convert_like (conv2, arg2);
          arg2 = convert_from_reference (arg2);
          arg2_type = TREE_TYPE (arg2);
          /* Even if CONV2 is a valid conversion, the result of the
             conversion may be invalid.  For example, if ARG3 has type
             "volatile X", and X does not have a copy constructor
             accepting a "volatile X&", then even if ARG2 can be
             converted to X, the conversion will fail.  */
          if (error_operand_p (arg2))
            result = error_mark_node;
        }
      else if (conv3 && (!conv3->bad_p || !conv2))
        {
          arg3 = convert_like (conv3, arg3);
          arg3 = convert_from_reference (arg3);
          arg3_type = TREE_TYPE (arg3);
          if (error_operand_p (arg3))
            result = error_mark_node;
        }

      /* Free all the conversions we allocated.  */
      obstack_free (&conversion_obstack, p);

      if (result)
        return result;

      /* If, after the conversion, both operands have class type,
         treat the cv-qualification of both operands as if it were the
         union of the cv-qualification of the operands.

         The standard is not clear about what to do in this
         circumstance.  For example, if the first operand has type
         "const X" and the second operand has a user-defined
         conversion to "volatile X", what is the type of the second
         operand after this step?  Making it be "const X" (matching
         the first operand) seems wrong, as that discards the
         qualification without actually performing a copy.  Leaving it
         as "volatile X" seems wrong as that will result in the
         conditional expression failing altogether, even though,
         according to this step, the one operand could be converted to
         the type of the other.  */
      if ((conv2 || conv3)
          && CLASS_TYPE_P (arg2_type)
          && TYPE_QUALS (arg2_type) != TYPE_QUALS (arg3_type))
        arg2_type = arg3_type =
          cp_build_qualified_type (arg2_type,
                                   TYPE_QUALS (arg2_type)
                                   | TYPE_QUALS (arg3_type));
    }

  /* [expr.cond]

     If the second and third operands are lvalues and have the same
     type, the result is of that type and is an lvalue.  */
  if (real_lvalue_p (arg2)
      && real_lvalue_p (arg3)
      && same_type_p (arg2_type, arg3_type))
    {
      result_type = arg2_type;
      goto valid_operands;
    }

  /* [expr.cond]

     Otherwise, the result is an rvalue.  If the second and third
     operand do not have the same type, and either has (possibly
     cv-qualified) class type, overload resolution is used to
     determine the conversions (if any) to be applied to the operands
     (_over.match.oper_, _over.built_).  */
  lvalue_p = false;
  if (!same_type_p (arg2_type, arg3_type)
      && (CLASS_TYPE_P (arg2_type) || CLASS_TYPE_P (arg3_type)))
    {
      tree args[3];
      conversion *conv;
      bool any_viable_p;

      /* Rearrange the arguments so that add_builtin_candidate only has
         to know about two args.  In build_builtin_candidates, the
         arguments are unscrambled.  */
      args[0] = arg2;
      args[1] = arg3;
      args[2] = arg1;
      add_builtin_candidates (&candidates,
                              COND_EXPR,
                              NOP_EXPR,
                              ansi_opname (COND_EXPR),
                              args,
                              LOOKUP_NORMAL);

      /* [expr.cond]

         If the overload resolution fails, the program is
         ill-formed.  */
      candidates = splice_viable (candidates, pedantic, &any_viable_p);
      if (!any_viable_p)
        {
          op_error (COND_EXPR, NOP_EXPR, arg1, arg2, arg3, "no match");
          print_z_candidates (candidates);
          return error_mark_node;
        }
      cand = tourney (candidates);
      if (!cand)
        {
          op_error (COND_EXPR, NOP_EXPR, arg1, arg2, arg3, "no match");
          print_z_candidates (candidates);
          return error_mark_node;
        }

      /* [expr.cond]

         Otherwise, the conversions thus determined are applied, and
         the converted operands are used in place of the original
         operands for the remainder of this section.  */
      conv = cand->convs[0];
      arg1 = convert_like (conv, arg1);
      conv = cand->convs[1];
      arg2 = convert_like (conv, arg2);
      conv = cand->convs[2];
      arg3 = convert_like (conv, arg3);
    }

  /* [expr.cond]

     Lvalue-to-rvalue (_conv.lval_), array-to-pointer (_conv.array_),
     and function-to-pointer (_conv.func_) standard conversions are
     performed on the second and third operands.

     We need to force the lvalue-to-rvalue conversion here for class types,
     so we get TARGET_EXPRs; trying to deal with a COND_EXPR of class rvalues
     that isn't wrapped with a TARGET_EXPR plays havoc with exception
     regions.  */

  arg2 = force_rvalue (arg2);
  if (!CLASS_TYPE_P (arg2_type))
    arg2_type = TREE_TYPE (arg2);

  arg3 = force_rvalue (arg3);
  if (!CLASS_TYPE_P (arg2_type))
    arg3_type = TREE_TYPE (arg3);

  if (arg2 == error_mark_node || arg3 == error_mark_node)
    return error_mark_node;

  /* [expr.cond]

     After those conversions, one of the following shall hold:

     --The second and third operands have the same type; the result  is  of
       that type.  */
  if (same_type_p (arg2_type, arg3_type))
    result_type = arg2_type;
  /* [expr.cond]

     --The second and third operands have arithmetic or enumeration
       type; the usual arithmetic conversions are performed to bring
       them to a common type, and the result is of that type.  */
  else if ((ARITHMETIC_TYPE_P (arg2_type)
            || TREE_CODE (arg2_type) == ENUMERAL_TYPE)
           && (ARITHMETIC_TYPE_P (arg3_type)
               || TREE_CODE (arg3_type) == ENUMERAL_TYPE))
    {
      /* In this case, there is always a common type.  */
      result_type = type_after_usual_arithmetic_conversions (arg2_type,
                                                             arg3_type);

      if (TREE_CODE (arg2_type) == ENUMERAL_TYPE
          && TREE_CODE (arg3_type) == ENUMERAL_TYPE)
         warning (0, "enumeral mismatch in conditional expression: %qT vs %qT",
                   arg2_type, arg3_type);
      else if (extra_warnings
               && ((TREE_CODE (arg2_type) == ENUMERAL_TYPE
                    && !same_type_p (arg3_type, type_promotes_to (arg2_type)))
                   || (TREE_CODE (arg3_type) == ENUMERAL_TYPE
                       && !same_type_p (arg2_type, type_promotes_to (arg3_type)))))
        warning (0, "enumeral and non-enumeral type in conditional expression");

      arg2 = perform_implicit_conversion (result_type, arg2);
      arg3 = perform_implicit_conversion (result_type, arg3);
    }
  /* [expr.cond]

     --The second and third operands have pointer type, or one has
       pointer type and the other is a null pointer constant; pointer
       conversions (_conv.ptr_) and qualification conversions
       (_conv.qual_) are performed to bring them to their composite
       pointer type (_expr.rel_).  The result is of the composite
       pointer type.

     --The second and third operands have pointer to member type, or
       one has pointer to member type and the other is a null pointer
       constant; pointer to member conversions (_conv.mem_) and
       qualification conversions (_conv.qual_) are performed to bring
       them to a common type, whose cv-qualification shall match the
       cv-qualification of either the second or the third operand.
       The result is of the common type.  */
  else if ((null_ptr_cst_p (arg2)
            && (TYPE_PTR_P (arg3_type) || TYPE_PTR_TO_MEMBER_P (arg3_type)))
           || (null_ptr_cst_p (arg3)
               && (TYPE_PTR_P (arg2_type) || TYPE_PTR_TO_MEMBER_P (arg2_type)))
           || (TYPE_PTR_P (arg2_type) && TYPE_PTR_P (arg3_type))
           || (TYPE_PTRMEM_P (arg2_type) && TYPE_PTRMEM_P (arg3_type))
           || (TYPE_PTRMEMFUNC_P (arg2_type) && TYPE_PTRMEMFUNC_P (arg3_type)))
    {
      result_type = composite_pointer_type (arg2_type, arg3_type, arg2,
                                            arg3, "conditional expression");
      if (result_type == error_mark_node)
        return error_mark_node;
      arg2 = perform_implicit_conversion (result_type, arg2);
      arg3 = perform_implicit_conversion (result_type, arg3);
    }

  if (!result_type)
    {
      error ("operands to ?: have different types %qT and %qT",
             arg2_type, arg3_type);
      return error_mark_node;
    }

 valid_operands:
  result = fold_if_not_in_template (build3 (COND_EXPR, result_type, arg1,
                                            arg2, arg3));
  /* We can't use result_type below, as fold might have returned a
     throw_expr.  */

  if (!lvalue_p)
    {
      /* Expand both sides into the same slot, hopefully the target of
         the ?: expression.  We used to check for TARGET_EXPRs here,
         but now we sometimes wrap them in NOP_EXPRs so the test would
         fail.  */
      if (CLASS_TYPE_P (TREE_TYPE (result)))
        result = get_target_expr (result);
      /* If this expression is an rvalue, but might be mistaken for an
         lvalue, we must add a NON_LVALUE_EXPR.  */
      result = rvalue (result);
    }

  return result;
}

/* OPERAND is an operand to an expression.  Perform necessary steps
   required before using it.  If OPERAND is NULL_TREE, NULL_TREE is
   returned.  */

static tree
prep_operand (tree operand)
{
  if (operand)
    {
      if (CLASS_TYPE_P (TREE_TYPE (operand))
          && CLASSTYPE_TEMPLATE_INSTANTIATION (TREE_TYPE (operand)))
        /* Make sure the template type is instantiated now.  */
        instantiate_class_template (TYPE_MAIN_VARIANT (TREE_TYPE (operand)));
    }

  return operand;
}

/* Add each of the viable functions in FNS (a FUNCTION_DECL or
   OVERLOAD) to the CANDIDATES, returning an updated list of
   CANDIDATES.  The ARGS are the arguments provided to the call,
   without any implicit object parameter.  The EXPLICIT_TARGS are
   explicit template arguments provided.  TEMPLATE_ONLY is true if
   only template functions should be considered.  CONVERSION_PATH,
   ACCESS_PATH, and FLAGS are as for add_function_candidate.  */

static void
add_candidates (tree fns, tree args,
                tree explicit_targs, bool template_only,
                tree conversion_path, tree access_path,
                int flags,
                struct z_candidate **candidates)
{
  tree ctype;
  tree non_static_args;

  ctype = conversion_path ? BINFO_TYPE (conversion_path) : NULL_TREE;
  /* Delay creating the implicit this parameter until it is needed.  */
  non_static_args = NULL_TREE;

  while (fns)
    {
      tree fn;
      tree fn_args;

      fn = OVL_CURRENT (fns);
      /* Figure out which set of arguments to use.  */
      if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn))
        {
          /* If this function is a non-static member, prepend the implicit
             object parameter.  */
          if (!non_static_args)
            non_static_args = tree_cons (NULL_TREE,
                                         build_this (TREE_VALUE (args)),
                                         TREE_CHAIN (args));
          fn_args = non_static_args;
        }
      else
        /* Otherwise, just use the list of arguments provided.  */
        fn_args = args;

      if (TREE_CODE (fn) == TEMPLATE_DECL)
        add_template_candidate (candidates,
                                fn,
                                ctype,
                                explicit_targs,
                                fn_args,
                                NULL_TREE,
                                access_path,
                                conversion_path,
                                flags,
                                DEDUCE_CALL);
      else if (!template_only)
        add_function_candidate (candidates,
                                fn,
                                ctype,
                                fn_args,
                                access_path,
                                conversion_path,
                                flags);
      fns = OVL_NEXT (fns);
    }
}

tree
build_new_op (enum tree_code code, int flags, tree arg1, tree arg2, tree arg3,
              bool *overloaded_p)
{
  struct z_candidate *candidates = 0, *cand;
  tree arglist, fnname;
  tree args[3];
  tree result = NULL_TREE;
  bool result_valid_p = false;
  enum tree_code code2 = NOP_EXPR;
  conversion *conv;
  void *p;
  bool strict_p;
  bool any_viable_p;
  bool expl_eq_arg1 = false;

  if (error_operand_p (arg1)
      || error_operand_p (arg2)
      || error_operand_p (arg3))
    return error_mark_node;

  if (code == MODIFY_EXPR)
    {
      code2 = TREE_CODE (arg3);
      arg3 = NULL_TREE;
      fnname = ansi_assopname (code2);
    }
  else
    fnname = ansi_opname (code);

  arg1 = prep_operand (arg1);

  switch (code)
    {
    case NEW_EXPR:
    case VEC_NEW_EXPR:
    case VEC_DELETE_EXPR:
    case DELETE_EXPR:
      /* Use build_op_new_call and build_op_delete_call instead.  */
      gcc_unreachable ();

    case CALL_EXPR:
      return build_object_call (arg1, arg2);

    case TRUTH_ORIF_EXPR:
    case TRUTH_ANDIF_EXPR:
    case TRUTH_AND_EXPR:
    case TRUTH_OR_EXPR:
      if (COMPARISON_CLASS_P (arg1))
        expl_eq_arg1 = true;
    default:
      break;
    }

  arg2 = prep_operand (arg2);
  arg3 = prep_operand (arg3);

  if (code == COND_EXPR)
    {
      if (arg2 == NULL_TREE
          || TREE_CODE (TREE_TYPE (arg2)) == VOID_TYPE
          || TREE_CODE (TREE_TYPE (arg3)) == VOID_TYPE
          || (! IS_OVERLOAD_TYPE (TREE_TYPE (arg2))
              && ! IS_OVERLOAD_TYPE (TREE_TYPE (arg3))))
        goto builtin;
    }
  else if (! IS_OVERLOAD_TYPE (TREE_TYPE (arg1))
           && (! arg2 || ! IS_OVERLOAD_TYPE (TREE_TYPE (arg2))))
    goto builtin;

  if (code == POSTINCREMENT_EXPR || code == POSTDECREMENT_EXPR)
    arg2 = integer_zero_node;

  arglist = NULL_TREE;
  if (arg3)
    arglist = tree_cons (NULL_TREE, arg3, arglist);
  if (arg2)
    arglist = tree_cons (NULL_TREE, arg2, arglist);
  arglist = tree_cons (NULL_TREE, arg1, arglist);

  /* Get the high-water mark for the CONVERSION_OBSTACK.  */
  p = conversion_obstack_alloc (0);

  /* Add namespace-scope operators to the list of functions to
     consider.  */
  add_candidates (lookup_function_nonclass (fnname, arglist, /*block_p=*/true),
                  arglist, NULL_TREE, false, NULL_TREE, NULL_TREE,
                  flags, &candidates);
  /* Add class-member operators to the candidate set.  */
  if (CLASS_TYPE_P (TREE_TYPE (arg1)))
    {
      tree fns;

      fns = lookup_fnfields (TREE_TYPE (arg1), fnname, 1);
      if (fns == error_mark_node)
        {
          result = error_mark_node;
          goto user_defined_result_ready;
        }
      if (fns)
        add_candidates (BASELINK_FUNCTIONS (fns), arglist,
                        NULL_TREE, false,
                        BASELINK_BINFO (fns),
                        TYPE_BINFO (TREE_TYPE (arg1)),
                        flags, &candidates);
    }

  /* Rearrange the arguments for ?: so that add_builtin_candidate only has
     to know about two args; a builtin candidate will always have a first
     parameter of type bool.  We'll handle that in
     build_builtin_candidate.  */
  if (code == COND_EXPR)
    {
      args[0] = arg2;
      args[1] = arg3;
      args[2] = arg1;
    }
  else
    {
      args[0] = arg1;
      args[1] = arg2;
      args[2] = NULL_TREE;
    }

  add_builtin_candidates (&candidates, code, code2, fnname, args, flags);

  switch (code)
    {
    case COMPOUND_EXPR:
    case ADDR_EXPR:
      /* For these, the built-in candidates set is empty
         [over.match.oper]/3.  We don't want non-strict matches
         because exact matches are always possible with built-in
         operators.  The built-in candidate set for COMPONENT_REF
         would be empty too, but since there are no such built-in
         operators, we accept non-strict matches for them.  */
      strict_p = true;
      break;

    default:
      strict_p = pedantic;
      break;
    }

  candidates = splice_viable (candidates, strict_p, &any_viable_p);
  if (!any_viable_p)
    {
      switch (code)
        {
        case POSTINCREMENT_EXPR:
        case POSTDECREMENT_EXPR:
          /* Look for an `operator++ (int)'.  If they didn't have
             one, then we fall back to the old way of doing things.  */
          if (flags & LOOKUP_COMPLAIN)
            pedwarn ("no %<%D(int)%> declared for postfix %qs, "
                     "trying prefix operator instead",
                     fnname,
                     operator_name_info[code].name);
          if (code == POSTINCREMENT_EXPR)
            code = PREINCREMENT_EXPR;
          else
            code = PREDECREMENT_EXPR;
          result = build_new_op (code, flags, arg1, NULL_TREE, NULL_TREE,
                                 overloaded_p);
          break;

          /* The caller will deal with these.  */
        case ADDR_EXPR:
        case COMPOUND_EXPR:
        case COMPONENT_REF:
          result = NULL_TREE;
          result_valid_p = true;
          break;

        default:
          if (flags & LOOKUP_COMPLAIN)
            {
              op_error (code, code2, arg1, arg2, arg3, "no match");
              print_z_candidates (candidates);
            }
          result = error_mark_node;
          break;
        }
    }
  else
    {
      cand = tourney (candidates);
      if (cand == 0)
        {
          if (flags & LOOKUP_COMPLAIN)
            {
              op_error (code, code2, arg1, arg2, arg3, "ambiguous overload");
              print_z_candidates (candidates);
            }
          result = error_mark_node;
        }
      else if (TREE_CODE (cand->fn) == FUNCTION_DECL)
        {
          if (overloaded_p)
            *overloaded_p = true;

          result = build_over_call (cand, LOOKUP_NORMAL);
        }
      else
        {
          /* Give any warnings we noticed during overload resolution.  */
          if (cand->warnings)
            {
              struct candidate_warning *w;
              for (w = cand->warnings; w; w = w->next)
                joust (cand, w->loser, 1);
            }

          /* Check for comparison of different enum types.  */
          switch (code)
            {
            case GT_EXPR:
            case LT_EXPR:
            case GE_EXPR:
            case LE_EXPR:
            case EQ_EXPR:
            case NE_EXPR:
              if (TREE_CODE (TREE_TYPE (arg1)) == ENUMERAL_TYPE
                  && TREE_CODE (TREE_TYPE (arg2)) == ENUMERAL_TYPE
                  && (TYPE_MAIN_VARIANT (TREE_TYPE (arg1))
                      != TYPE_MAIN_VARIANT (TREE_TYPE (arg2))))
                {
                  warning (0, "comparison between %q#T and %q#T",
                           TREE_TYPE (arg1), TREE_TYPE (arg2));
                }
              break;
            default:
              break;
            }

          /* We need to strip any leading REF_BIND so that bitfields
             don't cause errors.  This should not remove any important
             conversions, because builtins don't apply to class
             objects directly.  */
          conv = cand->convs[0];
          if (conv->kind == ck_ref_bind)
            conv = conv->u.next;
          arg1 = convert_like (conv, arg1);
          if (arg2)
            {
              conv = cand->convs[1];
              if (conv->kind == ck_ref_bind)
                conv = conv->u.next;
              arg2 = convert_like (conv, arg2);
            }
          if (arg3)
            {
              conv = cand->convs[2];
              if (conv->kind == ck_ref_bind)
                conv = conv->u.next;
              arg3 = convert_like (conv, arg3);
            }

          if (!expl_eq_arg1) 
            {
              warn_logical_operator (code, arg1, arg2);
              expl_eq_arg1 = true;
            }
        }
    }

 user_defined_result_ready:

  /* Free all the conversions we allocated.  */
  obstack_free (&conversion_obstack, p);

  if (result || result_valid_p)
    return result;

 builtin:
  switch (code)
    {
    case MODIFY_EXPR:
      return build_modify_expr (arg1, code2, arg2);

    case INDIRECT_REF:
      return build_indirect_ref (arg1, "unary *");

    case TRUTH_ANDIF_EXPR:
    case TRUTH_ORIF_EXPR:
    case TRUTH_AND_EXPR:
    case TRUTH_OR_EXPR:
      if (!expl_eq_arg1)
        warn_logical_operator (code, arg1, arg2);
    case PLUS_EXPR:
    case MINUS_EXPR:
    case MULT_EXPR:
    case TRUNC_DIV_EXPR:
    case GT_EXPR:
    case LT_EXPR:
    case GE_EXPR:
    case LE_EXPR:
    case EQ_EXPR:
    case NE_EXPR:
    case MAX_EXPR:
    case MIN_EXPR:
    case LSHIFT_EXPR:
    case RSHIFT_EXPR:
    case TRUNC_MOD_EXPR:
    case BIT_AND_EXPR:
    case BIT_IOR_EXPR:
    case BIT_XOR_EXPR:
      return cp_build_binary_op (code, arg1, arg2);

    case UNARY_PLUS_EXPR:
    case NEGATE_EXPR:
    case BIT_NOT_EXPR:
    case TRUTH_NOT_EXPR:
    case PREINCREMENT_EXPR:
    case POSTINCREMENT_EXPR:
    case PREDECREMENT_EXPR:
    case POSTDECREMENT_EXPR:
    case REALPART_EXPR:
    case IMAGPART_EXPR:
      return build_unary_op (code, arg1, candidates != 0);

    case ARRAY_REF:
      return build_array_ref (arg1, arg2);

    case COND_EXPR:
      return build_conditional_expr (arg1, arg2, arg3);

    case MEMBER_REF:
      return build_m_component_ref (build_indirect_ref (arg1, NULL), arg2);

      /* The caller will deal with these.  */
    case ADDR_EXPR:
    case COMPONENT_REF:
    case COMPOUND_EXPR:
      return NULL_TREE;

    default:
      gcc_unreachable ();
    }
  return NULL_TREE;
}

/* Build a call to operator delete.  This has to be handled very specially,
   because the restrictions on what signatures match are different from all
   other call instances.  For a normal delete, only a delete taking (void *)
   or (void *, size_t) is accepted.  For a placement delete, only an exact
   match with the placement new is accepted.

   CODE is either DELETE_EXPR or VEC_DELETE_EXPR.
   ADDR is the pointer to be deleted.
   SIZE is the size of the memory block to be deleted.
   GLOBAL_P is true if the delete-expression should not consider
   class-specific delete operators.
   PLACEMENT is the corresponding placement new call, or NULL_TREE.
   If PLACEMENT is non-NULL, then ALLOC_FN is the allocation function
   called to perform the placement new.  */

tree
build_op_delete_call (enum tree_code code, tree addr, tree size,
                      bool global_p, tree placement,
                      tree alloc_fn)
{
  tree fn = NULL_TREE;
  tree fns, fnname, argtypes, type;
  int pass;

  if (addr == error_mark_node)
    return error_mark_node;

  type = strip_array_types (TREE_TYPE (TREE_TYPE (addr)));

  fnname = ansi_opname (code);

  if (CLASS_TYPE_P (type)
      && COMPLETE_TYPE_P (complete_type (type))
      && !global_p)
    /* In [class.free]

       If the result of the lookup is ambiguous or inaccessible, or if
       the lookup selects a placement deallocation function, the
       program is ill-formed.

       Therefore, we ask lookup_fnfields to complain about ambiguity.  */
    {
      fns = lookup_fnfields (TYPE_BINFO (type), fnname, 1);
      if (fns == error_mark_node)
        return error_mark_node;
    }
  else
    fns = NULL_TREE;

  if (fns == NULL_TREE)
    fns = lookup_name_nonclass (fnname);

  /* Strip const and volatile from addr.  */
  addr = cp_convert (ptr_type_node, addr);

  if (placement)
    {
      /* Get the parameter types for the allocation function that is
         being called.  */
      gcc_assert (alloc_fn != NULL_TREE);
      argtypes = TREE_CHAIN (TYPE_ARG_TYPES (TREE_TYPE (alloc_fn)));
    }
  else
    {
      /* First try it without the size argument.  */
      argtypes = void_list_node;
    }

  /* We make two tries at finding a matching `operator delete'.  On
     the first pass, we look for a one-operator (or placement)
     operator delete.  If we're not doing placement delete, then on
     the second pass we look for a two-argument delete.  */
  for (pass = 0; pass < (placement ? 1 : 2); ++pass)
    {
      /* Go through the `operator delete' functions looking for one
         with a matching type.  */
      for (fn = BASELINK_P (fns) ? BASELINK_FUNCTIONS (fns) : fns;
           fn;
           fn = OVL_NEXT (fn))
        {
          tree t;

          /* The first argument must be "void *".  */
          t = TYPE_ARG_TYPES (TREE_TYPE (OVL_CURRENT (fn)));
          if (!same_type_p (TREE_VALUE (t), ptr_type_node))
            continue;
          t = TREE_CHAIN (t);
          /* On the first pass, check the rest of the arguments.  */
          if (pass == 0)
            {
              tree a = argtypes;
              while (a && t)
                {
                  if (!same_type_p (TREE_VALUE (a), TREE_VALUE (t)))
                    break;
                  a = TREE_CHAIN (a);
                  t = TREE_CHAIN (t);
                }
              if (!a && !t)
                break;
            }
          /* On the second pass, the second argument must be
             "s