cp-call.c

早期freebsd实现

/* Functions related to invoking methods and overloaded functions.
   Copyright (C) 1987, 1992 Free Software Foundation, Inc.
   Contributed by Michael Tiemann ([e-mail])

This file is part of GNU CC.

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

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

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


/* High-level class interface. */

#include "config.h"
#include "tree.h"
#include <stdio.h>
#include "cp-tree.h"
#include "flags.h"
#include "cp-class.h"

#include "obstack.h"
#define obstack_chunk_alloc xmalloc
#define obstack_chunk_free free

extern void sorry ();

extern tree build_function_call_maybe ();

extern int inhibit_warnings;
extern int flag_assume_nonnull_objects;
extern tree ctor_label, dtor_label;

/* From cp-typeck.c:  */
extern tree unary_complex_lvalue ();

/* Compute the ease with which a conversion can be performed
   between an expected and the given type.  */
static int convert_harshness ();

#define EVIL_HARSHNESS(ARG) ((ARG) & 1)
#define USER_HARSHNESS(ARG) ((ARG) & 2)
#define CONTRAVARIANT_HARSHNESS(ARG) ((ARG) & 4)
#define BASE_DERIVED_HARSHNESS(ARG) ((ARG) & 8)
#define INT_TO_BD_HARSHNESS(ARG) (((ARG) << 4) | 8)
#define INT_FROM_BD_HARSHNESS(ARG) ((ARG) >> 4)
#define INT_TO_EASY_HARSHNESS(ARG) ((ARG) << 4)
#define INT_FROM_EASY_HARSHNESS(ARG) ((ARG) >> 4)
#define ONLY_EASY_HARSHNESS(ARG) (((ARG) & 15) == 0)
#define CONST_HARSHNESS(ARG) ((ARG) & 1024)

/* Ordering function for overload resolution.  */
int
rank_for_overload (x, y)
     struct candidate *x, *y;
{
  if (y->evil - x->evil)
    return y->evil - x->evil;
  if (CONST_HARSHNESS (y->harshness[0]) ^ CONST_HARSHNESS (x->harshness[0]))
    return y->harshness[0] - x->harshness[0];
  if (y->user - x->user)
    return y->user - x->user;
  if (y->b_or_d - x->b_or_d)
    return y->b_or_d - x->b_or_d;
  return y->easy - x->easy;
}

/* TYPE is the type we wish to convert to.  PARM is the parameter
   we have to work with.  We use a somewhat arbitrary cost function
   to measure this conversion.  */
static int
convert_harshness (type, parmtype, parm)
     register tree type, parmtype;
     tree parm;
{
  register enum tree_code codel = TREE_CODE (type);
  register enum tree_code coder = TREE_CODE (parmtype);

#ifdef GATHER_STATISTICS
  n_convert_harshness++;
#endif

  if (TYPE_MAIN_VARIANT (parmtype) == TYPE_MAIN_VARIANT (type))
    return 0;

  if (coder == ERROR_MARK)
    return 1;

  if (codel == POINTER_TYPE
      && (coder == METHOD_TYPE || coder == FUNCTION_TYPE))
    {
      tree p1, p2;
      int harshness, new_harshness;

      /* Get to the METHOD_TYPE or FUNCTION_TYPE that this might be.  */
      type = TREE_TYPE (type);

      if (coder != TREE_CODE (type))
	return 1;

      harshness = 0;

      /* We allow the default conversion between function type
	 and pointer-to-function type for free.  */
      if (type == parmtype)
	return 0;

      /* Compare return types.  */
      p1 = TREE_TYPE (type);
      p2 = TREE_TYPE (parmtype);
      new_harshness = convert_harshness (p1, p2, 0);
      if (new_harshness & 1)
	return 1;

      if (BASE_DERIVED_HARSHNESS (new_harshness))
	{
	  tree binfo;

	  /* This only works for pointers.  */
	  if (TREE_CODE (p1) != POINTER_TYPE
	      && TREE_CODE (p1) != REFERENCE_TYPE)
	    return 1;

	  p1 = TREE_TYPE (p1);
	  p2 = TREE_TYPE (p2);
	  if (CONTRAVARIANT_HARSHNESS (new_harshness))
	    binfo = get_binfo (p2, p1, 0);
	  else
	    binfo = get_binfo (p1, p2, 0);

	  if (! BINFO_OFFSET_ZEROP (binfo))
	    {
	      static int explained;
	      if (CONTRAVARIANT_HARSHNESS (new_harshness))
		message_2_types (sorry, "cannot cast `%d' to `%d' at function call site", p2, p1);
	      else
		message_2_types (sorry, "cannot cast `%d' to `%d' at function call site", p1, p2);

	      if (! explained++)
		sorry ("(because pointer values change during conversion)");
	      return 1;
	    }
	}

      harshness |= new_harshness;

      p1 = TYPE_ARG_TYPES (type);
      p2 = TYPE_ARG_TYPES (parmtype);
      while (p1 && p2)
	{
	  new_harshness = convert_harshness (TREE_VALUE (p1), TREE_VALUE (p2), 0);
	  if (EVIL_HARSHNESS (new_harshness))
	    return 1;

	  if (BASE_DERIVED_HARSHNESS (new_harshness))
	    {
	      /* This only works for pointers and references. */
	      if (TREE_CODE (TREE_VALUE (p1)) != POINTER_TYPE
		  && TREE_CODE (TREE_VALUE (p1)) != REFERENCE_TYPE)
		return 1;
	      new_harshness ^= CONTRAVARIANT_HARSHNESS (new_harshness);
	      harshness |= new_harshness;
	    }
	  /* This trick allows use to accumulate easy type
	     conversions without messing up the bits that encode
	     info about more involved things.  */
	  else if (ONLY_EASY_HARSHNESS (new_harshness))
	    harshness += new_harshness;
	  else
	    harshness |= new_harshness;
	  p1 = TREE_CHAIN (p1);
	  p2 = TREE_CHAIN (p2);
	}
      if (p1 == p2)
	return harshness;
      if (p2)
	return 1;
      if (p1)
	return harshness | (TREE_PURPOSE (p1) == NULL_TREE);
    }
  else if (codel == POINTER_TYPE && coder == OFFSET_TYPE)
    {
      int harshness;

      /* Get to the OFFSET_TYPE that this might be.  */
      type = TREE_TYPE (type);

      if (coder != TREE_CODE (type))
	return 1;

      harshness = 0;

      if (TYPE_OFFSET_BASETYPE (type) == TYPE_OFFSET_BASETYPE (parmtype))
	harshness = 0;
      else if (UNIQUELY_DERIVED_FROM_P (TYPE_OFFSET_BASETYPE (type),
			       TYPE_OFFSET_BASETYPE (parmtype)))
	harshness = INT_TO_BD_HARSHNESS (1);
      else if (UNIQUELY_DERIVED_FROM_P (TYPE_OFFSET_BASETYPE (parmtype),
			       TYPE_OFFSET_BASETYPE (type)))
	harshness = CONTRAVARIANT_HARSHNESS (-1);
      else
	return 1;
      /* Now test the OFFSET_TYPE's target compatibility.  */
      type = TREE_TYPE (type);
      parmtype = TREE_TYPE (parmtype);
    }

  if (coder == UNKNOWN_TYPE)
    {
      if (codel == FUNCTION_TYPE
	  || codel == METHOD_TYPE
	  || (codel == POINTER_TYPE
	      && (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
		  || TREE_CODE (TREE_TYPE (type)) == METHOD_TYPE)))
	return 0;
      return 1;
    }

  if (coder == VOID_TYPE)
    return 1;

  if (codel == ENUMERAL_TYPE || codel == INTEGER_TYPE)
    {
      /* Control equivalence of ints an enums.  */

      if (codel == ENUMERAL_TYPE
	  && flag_int_enum_equivalence == 0)
	{
	  /* Enums can be converted to ints, but not vice-versa.  */
	  if (coder != ENUMERAL_TYPE
	      || TYPE_MAIN_VARIANT (type) != TYPE_MAIN_VARIANT (parmtype))
	    return 1;
	}

      /* else enums and ints (almost) freely interconvert.  */

      if (coder == INTEGER_TYPE || coder == ENUMERAL_TYPE)
	{
	  int easy = TREE_UNSIGNED (type) ^ TREE_UNSIGNED (parmtype);
	  if (codel != coder)
	    easy += 1;
	  if (TYPE_MODE (type) != TYPE_MODE (parmtype))
	    easy += 2;
	  return INT_TO_EASY_HARSHNESS (easy);
	}
      else if (coder == REAL_TYPE)
	return INT_TO_EASY_HARSHNESS (4);
    }

  if (codel == REAL_TYPE)
    if (coder == REAL_TYPE)
      /* Shun converting between float and double if a choice exists.  */
      {
	if (TYPE_MODE (type) != TYPE_MODE (parmtype))
	  return INT_TO_EASY_HARSHNESS (2);
	return 0;
      }
    else if (coder == INTEGER_TYPE || coder == ENUMERAL_TYPE)
      return INT_TO_EASY_HARSHNESS (4);

  /* convert arrays which have not previously been converted.  */
  if (codel == ARRAY_TYPE)
    codel = POINTER_TYPE;
  if (coder == ARRAY_TYPE)
    coder = POINTER_TYPE;

  /* Conversions among pointers */
  if (codel == POINTER_TYPE && coder == POINTER_TYPE)
    {
      register tree ttl = TYPE_MAIN_VARIANT (TREE_TYPE (type));
      register tree ttr = TYPE_MAIN_VARIANT (TREE_TYPE (parmtype));
      int penalty = 4 * (ttl != ttr);
      /* Anything converts to void *.  void * converts to anything.
	 Since these may be `const void *' (etc.) use VOID_TYPE
	 instead of void_type_node.
	 Otherwise, the targets must be the same,
	 except that we do allow (at some cost) conversion
	 between signed and unsinged pointer types.  */

      if ((TREE_CODE (ttl) == METHOD_TYPE
	   || TREE_CODE (ttl) == FUNCTION_TYPE)
	  && TREE_CODE (ttl) == TREE_CODE (ttr))
	{
	  if (comptypes (ttl, ttr, -1))
	    return INT_TO_EASY_HARSHNESS (penalty);
	  return 1;
	}

      if (!(TREE_CODE (ttl) == VOID_TYPE
	    || TREE_CODE (ttr) == VOID_TYPE
	    || (TREE_UNSIGNED (ttl) ^ TREE_UNSIGNED (ttr)
		&& (ttl = unsigned_type (ttl),
		    ttr = unsigned_type (ttr),
		    penalty = 10, 0))
	    || (comp_target_types (ttl, ttr, 0))))
	return 1;

      if (penalty == 10)
	return INT_TO_EASY_HARSHNESS (10);
      if (ttr == ttl)
	return INT_TO_BD_HARSHNESS (0);

      if (TREE_CODE (ttl) == RECORD_TYPE && TREE_CODE (ttr) == RECORD_TYPE)
	{
	  int b_or_d = get_base_distance (ttl, ttr, 0, 0);
	  if (b_or_d < 0)
	    {
	      b_or_d = get_base_distance (ttr, ttl, 0, 0);
	      if (b_or_d < 0)
		return 1;
	      return CONTRAVARIANT_HARSHNESS (-1);
	    }
	  return INT_TO_BD_HARSHNESS (b_or_d);
	}
      /* If converting from a `class*' to a `void*', make it
	 less favorable than any inheritance relationship.  */
      if (TREE_CODE (ttl) == VOID_TYPE && IS_AGGR_TYPE (ttr))
	return INT_TO_BD_HARSHNESS (CLASSTYPE_MAX_DEPTH (ttr)+1);
      return INT_TO_EASY_HARSHNESS (penalty);
    }

  if (codel == POINTER_TYPE && coder == INTEGER_TYPE)
    {
      /* This is not a bad match, but don't let it beat
	 integer-enum combinations.  */
      if (parm && integer_zerop (parm))
	return INT_TO_EASY_HARSHNESS (4);
    }

  /* C++: one of the types must be a reference type.  */
  {
    tree ttl, ttr;
    register tree intype = TYPE_MAIN_VARIANT (parmtype);
    register enum tree_code form = TREE_CODE (intype);
    int penalty;

    if (codel == REFERENCE_TYPE || coder == REFERENCE_TYPE)
      {
	ttl = TYPE_MAIN_VARIANT (type);

	if (codel == REFERENCE_TYPE)
	  {
	    ttl = TREE_TYPE (ttl);

	    /* When passing a non-const argument into a const reference,
	       dig it a little, so a non-const reference is preferred over
	       this one. (mrs) */
	    if (TREE_READONLY (ttl) && ! TREE_READONLY (parm))
	      penalty = 2;
	    else
	      penalty = 0;

	    ttl = TYPE_MAIN_VARIANT (ttl);

	    if (form == OFFSET_TYPE)
	      {
		intype = TREE_TYPE (intype);
		form = TREE_CODE (intype);
	      }

	    if (form == REFERENCE_TYPE)
	      {
		intype = TYPE_MAIN_VARIANT (TREE_TYPE (intype));

		if (ttl == intype)
		  return 0;
		penalty = 2;
	      }
	    else
	      {
		/* Can reference be built up?  */
		if (ttl == intype && penalty == 0) {
		  /* Becuase the READONLY bits are not always in the type,
		     this extra check is necessary.  The problem should
		     be fixed someplace else, and this extra code removed.

		     Also, if type if a reference, the readonly bits could
		     either be in the outer type (with reference) or on the
		     inner type (the thing being referenced).  (mrs)  */
		  if (TREE_READONLY (parm)
		      && ! (TYPE_READONLY (type)
			    || (TREE_CODE (type) == REFERENCE_TYPE
				&& TYPE_READONLY (TREE_TYPE (type)))))
		    penalty = 2;
		  else
		    return 0;
		}
		else
		  penalty = 2;
	      }
	  }
	else if (form == REFERENCE_TYPE)
	  {
	    if (parm)
	      {
		tree tmp = convert_from_reference (parm);
		intype = TYPE_MAIN_VARIANT (TREE_TYPE (tmp));
	      }
	    else
	      {
		intype = parmtype;
		do
		  {
		    intype = TREE_TYPE (intype);
		  }
		while (TREE_CODE (intype) == REFERENCE_TYPE);
		intype = TYPE_MAIN_VARIANT (intype);
	      }

	    if (ttl == intype)
	      return 0;
	    else
	      penalty = 2;
	  }

	if (TREE_UNSIGNED (ttl) ^ TREE_UNSIGNED (intype))
	  {
	    ttl = unsigned_type (ttl);
	    intype = unsigned_type (intype);
	    penalty += 2;
	  }

	ttr = intype;

	/* If the initializer is not an lvalue, then it does not