cp-cvt.c

早期freebsd实现

      type = TYPE_MAIN_VARIANT (TREE_TYPE (xtype));
      for (n_variants = 0; type; type = TYPE_NEXT_VARIANT (type))
	n_variants++;
      typenames = (tree *)alloca (n_variants * sizeof (tree));
      for (n_variants = 0, type = TYPE_MAIN_VARIANT (TREE_TYPE (xtype));
	   type; n_variants++, type = TYPE_NEXT_VARIANT (type))
	{
	  if (type == TREE_TYPE (xtype))
	    typenames[n_variants] = typename;
	  else if (TREE_CODE (xtype) == POINTER_TYPE)
	    typenames[n_variants] = build_typename_overload (build_pointer_type (type));
	  else
	    typenames[n_variants] = build_typename_overload (build_reference_type (type));
	}
    }

  save_basetype = basetype;
  type = xtype;

  while (TYPE_HAS_CONVERSION (basetype))
    {
      int i;
      if (lookup_fnfields (TYPE_BINFO (basetype), typename, 0))
	return build_type_conversion_1 (xtype, basetype, expr, typename, for_sure);
      for (i = 0; i < n_variants; i++)
	if (typenames[i] != typename
	    && lookup_fnfields (TYPE_BINFO (basetype), typenames[i], 0))
	  return build_type_conversion_1 (xtype, basetype, expr, typenames[i], for_sure);

      if (TYPE_BINFO_BASETYPES (basetype))
	basetype = TYPE_BINFO_BASETYPE (basetype, 0);
      else break;
    }

  if (TREE_CODE (type) == REFERENCE_TYPE)
    {
      tree first_arg = expr;
      type = TYPE_MAIN_VARIANT (TREE_TYPE (type));
      basetype = save_basetype;

      /* May need to build a temporary for this.  */
      while (TYPE_HAS_CONVERSION (basetype))
	{
	  if (lookup_fnfields (TYPE_BINFO (basetype), typename, 0))
	    {
	      int flags;

	      if (for_sure == 0)
		{
		  if (! lvalue_p (expr))
		    first_arg = build1 (NOP_EXPR, TYPE_POINTER_TO (basetype), integer_zero_node);
		  flags = LOOKUP_PROTECT;
		}
	      else
		flags = LOOKUP_NORMAL;
	      rval = build_method_call (first_arg, constructor_name (typename),
					NULL_TREE, NULL_TREE, flags);
	      if (rval == error_mark_node)
		{
		  if (for_sure == 0)
		    return NULL_TREE;
		  return error_mark_node;
		}
	      TREE_VALUE (TREE_OPERAND (rval, 1)) = expr;

	      if (IS_AGGR_TYPE (type))
		{
		  tree init = build_method_call (NULL_TREE,
						 constructor_name (type),
						 build_tree_list (NULL_TREE, rval), NULL_TREE, LOOKUP_NORMAL);
		  tree temp = build_cplus_new (type, init, 1);
		  return build_up_reference (TYPE_REFERENCE_TO (type), temp,
					     LOOKUP_COMPLAIN, 1);
		}
	      return convert (xtype, rval);
	    }
	  if (TYPE_BINFO_BASETYPES (basetype))
	    basetype = TYPE_BINFO_BASETYPE (basetype, 0);
	  else break;
	}
      /* No free conversions for reference types, right?.  */
      return NULL_TREE;
    }

  if (exact_conversion)
    return NULL_TREE;

  /* No perfect match found, try default.  */
  if (code == CONVERT_EXPR && TREE_CODE (type) == POINTER_TYPE)
    type_default = ptr_type_node;
  else if (type == void_type_node)
    return NULL_TREE;
  else
    {
      extern tree default_conversion ();
      tree tmp = default_conversion (build1 (NOP_EXPR, type, integer_zero_node));
      if (tmp == error_mark_node)
	return NULL_TREE;
      type_default = TREE_TYPE (tmp);
    }

  basetype = save_basetype;

  if (type_default != type)
    {
      type = type_default;
      typename = build_typename_overload (type);

      while (TYPE_HAS_CONVERSION (basetype))
	{
	  if (lookup_fnfields (TYPE_BINFO (basetype), typename, 0))
	    return build_type_conversion_1 (xtype, basetype, expr, typename, for_sure);
	  if (TYPE_BINFO_BASETYPES (basetype))
	    basetype = TYPE_BINFO_BASETYPE (basetype, 0);
	  else break;
	}
    }

 try_pointer:

  if (type == ptr_type_node)
    {
      /* Try converting to some other pointer type
	 with which void* is compatible, or in situations
	 in which void* is appropriate (such as &&,||, and !).  */

      while (TYPE_HAS_CONVERSION (basetype))
	{
	  if (CLASSTYPE_CONVERSION (basetype, ptr_conv) != 0)
	    {
	      if (CLASSTYPE_CONVERSION (basetype, ptr_conv) == error_mark_node)
		return error_mark_node;
	      typename = DECL_NAME (CLASSTYPE_CONVERSION (basetype, ptr_conv));
	      return build_type_conversion_1 (xtype, basetype, expr, typename, for_sure);
	    }
	  if (TYPE_BINFO_BASETYPES (basetype))
	    basetype = TYPE_BINFO_BASETYPE (basetype, 0);
	  else break;
	}
    }
  if (TREE_CODE (type) == POINTER_TYPE
      && TYPE_READONLY (TREE_TYPE (type))
      && TYPE_MAIN_VARIANT (TREE_TYPE (type)) == void_type_node)
    {
      /* Try converting to some other pointer type
	 with which const void* is compatible.  */

      while (TYPE_HAS_CONVERSION (basetype))
	{
	  if (CLASSTYPE_CONVERSION (basetype, constptr_conv) != 0)
	    {
	      if (CLASSTYPE_CONVERSION (basetype, constptr_conv) == error_mark_node)
		return error_mark_node;
	      typename = DECL_NAME (CLASSTYPE_CONVERSION (basetype, constptr_conv));
	      return build_type_conversion_1 (xtype, basetype, expr, typename, for_sure);
	    }
	  if (TYPE_BINFO_BASETYPES (basetype))
	    basetype = TYPE_BINFO_BASETYPE (basetype, 0);
	  else break;
	}
    }
  /* Use the longer or shorter conversion that is appropriate.  Have
     to check against 0 because the conversion may come from a baseclass.  */
  if (TREE_CODE (type) == INTEGER_TYPE
      && TYPE_HAS_INT_CONVERSION (basetype)
      && CLASSTYPE_CONVERSION (basetype, int_conv) != 0
      && CLASSTYPE_CONVERSION (basetype, int_conv) != error_mark_node)
    {
      typename = DECL_NAME (CLASSTYPE_CONVERSION (basetype, int_conv));
      return build_type_conversion_1 (xtype, basetype, expr, typename, for_sure);
    }
  if (TREE_CODE (type) == REAL_TYPE
      && TYPE_HAS_REAL_CONVERSION (basetype)
      && CLASSTYPE_CONVERSION (basetype, real_conv) != 0
      && CLASSTYPE_CONVERSION (basetype, real_conv) != error_mark_node)
    {
      typename = DECL_NAME (CLASSTYPE_CONVERSION (basetype, real_conv));
      return build_type_conversion_1 (xtype, basetype, expr, typename, for_sure);
    }

  /* THIS IS A KLUDGE.  */
  if (TREE_CODE (type) != POINTER_TYPE
      && (code == TRUTH_ANDIF_EXPR
	  || code == TRUTH_ORIF_EXPR
	  || code == TRUTH_NOT_EXPR))
    {
      /* Here's when we can convert to a pointer.  */
      type = ptr_type_node;
      goto try_pointer;
    }

  /* THESE ARE TOTAL KLUDGES.  */
  /* Default promotion yields no new alternatives, try
     conversions which are anti-default, such as

     double -> float or int -> unsigned or unsigned -> long

     */
  if (type_default == type
      && (TREE_CODE (type) == INTEGER_TYPE || TREE_CODE (type) == REAL_TYPE))
    {
      int not_again = 0;

      if (type == double_type_node)
	typename = build_typename_overload (float_type_node);
      else if (type == integer_type_node)
	typename = build_typename_overload (unsigned_type_node);
      else if (type == unsigned_type_node)
	typename = build_typename_overload (long_integer_type_node);

    again:
      basetype = save_basetype;
      while (TYPE_HAS_CONVERSION (basetype))
	{
	  if (lookup_fnfields (TYPE_BINFO (basetype), typename, 0))
	    return build_type_conversion_1 (xtype, basetype, expr, typename, for_sure);
	  if (TYPE_BINFO_BASETYPES (basetype))
	    basetype = TYPE_BINFO_BASETYPE (basetype, 0);
	  else break;
	}
      if (! not_again)
	{
	  if (type == integer_type_node)
	    {
	      typename = build_typename_overload (long_integer_type_node);
	      not_again = 1;
	      goto again;
	    }
	  else
	    {
	      typename = build_typename_overload (integer_type_node);
	      not_again = 1;
	      goto again;
	    }
	}
    }

  /* Now, try C promotions...

     float -> int
     int -> float, void *
     void * -> int

     Truthvalue conversions let us try to convert
     to pointer if we were going for int, and to int
     if we were looking for pointer.  */

    basetype = save_basetype;
    if (TREE_CODE (type) == REAL_TYPE
	|| (TREE_CODE (type) == POINTER_TYPE
	    && (code == TRUTH_ANDIF_EXPR
		|| code == TRUTH_ORIF_EXPR
		|| code == TRUTH_NOT_EXPR)))
      type = integer_type_node;
    else if (TREE_CODE (type) == INTEGER_TYPE)
      if (TYPE_HAS_REAL_CONVERSION (basetype))
	type = double_type_node;
      else
	return NULL_TREE;
    else
      return NULL_TREE;

    typename = build_typename_overload (type);
    while (TYPE_HAS_CONVERSION (basetype))
      {
	if (lookup_fnfields (TYPE_BINFO (basetype), typename, 0))
	  {
	    rval = build_type_conversion_1 (xtype, basetype, expr, typename, for_sure);
	    return rval;
	  }
	if (TYPE_BINFO_BASETYPES (basetype))
	  basetype = TYPE_BINFO_BASETYPE (basetype, 0);
	else
	  break;
      }

  return NULL_TREE;
}

/* Must convert two aggregate types to non-aggregate type.
   Attempts to find a non-ambiguous, "best" type conversion.

   Return 1 on success, 0 on failure.

   @@ What are the real semantics of this supposed to be??? */
int
build_default_binary_type_conversion (code, arg1, arg2)
     enum tree_code code;
     tree *arg1, *arg2;
{
  tree type1 = TREE_TYPE (*arg1);
  tree type2 = TREE_TYPE (*arg2);
  char *name1, *name2;

  if (TREE_CODE (type1) == REFERENCE_TYPE)
    type1 = TREE_TYPE (type1);
  if (TREE_CODE (type2) == REFERENCE_TYPE)
    type2 = TREE_TYPE (type2);

  if (TREE_CODE (TYPE_NAME (type1)) != TYPE_DECL)
    {
      tree decl = typedecl_for_tag (type1);
      if (decl)
	error ("type conversion nonexistent for type `%s'",
	       IDENTIFIER_POINTER (DECL_NAME (decl)));
      else
	error ("type conversion nonexistent for non-C++ type");
      return 0;
    }
  if (TREE_CODE (TYPE_NAME (type2)) != TYPE_DECL)
    {
      tree decl = typedecl_for_tag (type2);
      if (decl)
	error ("type conversion nonexistent for type `%s'",
	       IDENTIFIER_POINTER (decl));
      else
	error ("type conversion nonexistent for non-C++ type");
      return 0;
    }

  name1 = TYPE_NAME_STRING (type1);
  name2 = TYPE_NAME_STRING (type2);

  if (!IS_AGGR_TYPE (type1) || !TYPE_HAS_CONVERSION (type1))
    {
      if (!IS_AGGR_TYPE (type2) || !TYPE_HAS_CONVERSION (type2))
	error ("type conversion required for binary operation on types `%s' and `%s'",
	       name1, name2);
      else
	error ("type conversion required for type `%s'", name1);
      return 0;
    }
  else if (!IS_AGGR_TYPE (type2) || !TYPE_HAS_CONVERSION (type2))
    {
      error ("type conversion required for type `%s'", name2);
      return 0;
    }

  if (TYPE_HAS_INT_CONVERSION (type1) && TYPE_HAS_REAL_CONVERSION (type1))
    warning ("ambiguous type conversion for type `%s', defaulting to int", name1);
  if (TYPE_HAS_INT_CONVERSION (type1))
    {
      *arg1 = build_type_conversion (code, integer_type_node, *arg1, 1);
      *arg2 = build_type_conversion (code, integer_type_node, *arg2, 1);
    }
  else if (TYPE_HAS_REAL_CONVERSION (type1))
    {
      *arg1 = build_type_conversion (code, double_type_node, *arg1, 1);
      *arg2 = build_type_conversion (code, double_type_node, *arg2, 1);
    }
  else
    {
      *arg1 = build_type_conversion (code, ptr_type_node, *arg1, 1);
      if (*arg1 == error_mark_node)
	error ("ambiguous pointer conversion");
      *arg2 = build_type_conversion (code, ptr_type_node, *arg2, 1);
      if (*arg1 != error_mark_node && *arg2 == error_mark_node)
	error ("ambiguous pointer conversion");
    }
  if (*arg1 == 0)
    {
      if (*arg2 == 0 && type1 != type2)
	error ("default type conversion for types `%s' and `%s' failed",
	       name1, name2);
      else
	error ("default type conversion for type `%s' failed", name1);
      return 0;
    }
  else if (*arg2 == 0)
    {
      error ("default type conversion for type `%s' failed", name2);
      return 0;
    }
  return 1;
}

/* Must convert two aggregate types to non-aggregate type.
   Attempts to find a non-ambiguous, "best" type conversion.

   Return 1 on success, 0 on failure.

   The type of the argument is expected to be of aggregate type here.

   @@ What are the real semantics of this supposed to be??? */
int
build_default_unary_type_conversion (code, arg)
     enum tree_code code;
     tree *arg;
{
  tree type = TREE_TYPE (*arg);
  tree id = TREE_CODE (TYPE_NAME (type)) == TYPE_DECL
    ? TYPE_IDENTIFIER (type) : TYPE_NAME (type);
  char *name = IDENTIFIER_POINTER (id);

  if (! TYPE_HAS_CONVERSION (type))
    {
      error ("type conversion required for type `%s'", name);
      return 0;
    }

  if (TYPE_HAS_INT_CONVERSION (type) && TYPE_HAS_REAL_CONVERSION (type))
    warning ("ambiguous type conversion for type `%s', defaulting to int", name);
  if (TYPE_HAS_INT_CONVERSION (type))
    *arg = build_type_conversion (code, integer_type_node, *arg, 1);
  else if (TYPE_HAS_REAL_CONVERSION (type))
    *arg = build_type_conversion (code, double_type_node, *arg, 1);
  else
    {
      *arg = build_type_conversion (code, ptr_type_node, *arg, 1);
      if (*arg == error_mark_node)
	error ("ambiguous pointer conversion");
    }
  if (*arg == 0)
    {
      error ("default type conversion for type `%s' failed", name);
      return 0;
    }
  return 1;
}