typeck2.c

gcc-2.95.3 Linux下最常用的C编译器

	case FIX_TRUNC_EXPR:
	case FIX_FLOOR_EXPR:
	case FIX_ROUND_EXPR:
	case FIX_CEIL_EXPR:
	  ref = convert_pointer_to (binfo,
				    build_unary_op (ADDR_EXPR, TREE_OPERAND (datum, 0), 0));
	  break;
	default:
	  ref = convert_pointer_to (binfo,
				    build_unary_op (ADDR_EXPR, datum, 0));
	}
      return build_indirect_ref (ref, "(compiler error in build_scoped_ref)");
    }
  return error_mark_node;
}

/* Build a reference to an object specified by the C++ `->' operator.
   Usually this just involves dereferencing the object, but if the
   `->' operator is overloaded, then such overloads must be
   performed until an object which does not have the `->' operator
   overloaded is found.  An error is reported when circular pointer
   delegation is detected.  */

tree
build_x_arrow (datum)
     tree datum;
{
  tree types_memoized = NULL_TREE;
  register tree rval = datum;
  tree type = TREE_TYPE (rval);
  tree last_rval = NULL_TREE;

  if (type == error_mark_node)
    return error_mark_node;

  if (processing_template_decl)
    return build_min_nt (ARROW_EXPR, rval);

  if (TREE_CODE (rval) == OFFSET_REF)
    {
      rval = resolve_offset_ref (datum);
      type = TREE_TYPE (rval);
    }

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

  if (IS_AGGR_TYPE (type))
    {
      while ((rval = build_opfncall (COMPONENT_REF, LOOKUP_NORMAL, rval,
				     NULL_TREE, NULL_TREE)))
	{
	  if (rval == error_mark_node)
	    return error_mark_node;

	  if (value_member (TREE_TYPE (rval), types_memoized))
	    {
	      error ("circular pointer delegation detected");
	      return error_mark_node;
	    }
	  else
	    {
	      types_memoized = tree_cons (NULL_TREE, TREE_TYPE (rval),
					  types_memoized);
	    }
	  last_rval = rval;
	}     

      if (last_rval == NULL_TREE)
	{
	  cp_error ("base operand of `->' has non-pointer type `%T'", type);
	  return error_mark_node;
	}

      if (TREE_CODE (TREE_TYPE (last_rval)) == REFERENCE_TYPE)
	last_rval = convert_from_reference (last_rval);
    }
  else
    last_rval = default_conversion (rval);

  /* Signature pointers are not dereferenced.  */
  if (TYPE_LANG_SPECIFIC (TREE_TYPE (last_rval))
      && IS_SIGNATURE_POINTER (TREE_TYPE (last_rval)))
    return last_rval;

  if (TREE_CODE (TREE_TYPE (last_rval)) == POINTER_TYPE)
    return build_indirect_ref (last_rval, NULL_PTR);

  if (types_memoized)
    error ("result of `operator->()' yields non-pointer result");
  else
    error ("base operand of `->' is not a pointer");
  return error_mark_node;
}

/* Make an expression to refer to the COMPONENT field of
   structure or union value DATUM.  COMPONENT is an arbitrary
   expression.  DATUM has not already been checked out to be of
   aggregate type.

   For C++, COMPONENT may be a TREE_LIST.  This happens when we must
   return an object of member type to a method of the current class,
   but there is not yet enough typing information to know which one.
   As a special case, if there is only one method by that name,
   it is returned.  Otherwise we return an expression which other
   routines will have to know how to deal with later.  */

tree
build_m_component_ref (datum, component)
     tree datum, component;
{
  tree type;
  tree objtype = TREE_TYPE (datum);
  tree rettype;
  tree binfo;

  if (processing_template_decl)
    return build_min_nt (DOTSTAR_EXPR, datum, component);

  if (TYPE_PTRMEMFUNC_P (TREE_TYPE (component)))
    {
      type = TREE_TYPE (TYPE_PTRMEMFUNC_FN_TYPE (TREE_TYPE (component)));
      rettype = type;
    }
  else
    {
      type = TREE_TYPE (TREE_TYPE (component));
      rettype = TREE_TYPE (type);
    }

  if (datum == error_mark_node || component == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (type) != OFFSET_TYPE && TREE_CODE (type) != METHOD_TYPE)
    {
      cp_error ("`%E' cannot be used as a member pointer, since it is of type `%T'", component, type);
      return error_mark_node;
    }

  if (TREE_CODE (objtype) == REFERENCE_TYPE)
    objtype = TREE_TYPE (objtype);
  objtype = TYPE_MAIN_VARIANT (objtype);

  if (! IS_AGGR_TYPE (objtype))
    {
      cp_error ("cannot apply member pointer `%E' to `%E'", component, datum);
      cp_error ("which is of non-aggregate type `%T'", objtype);
      return error_mark_node;
    }

  binfo = get_binfo (TYPE_METHOD_BASETYPE (type), objtype, 1);
  if (binfo == NULL_TREE)
    {
      cp_error ("member type `%T::' incompatible with object type `%T'",
		TYPE_METHOD_BASETYPE (type), objtype);
      return error_mark_node;
    }
  else if (binfo == error_mark_node)
    return error_mark_node;

  component = build (OFFSET_REF, rettype, datum, component);
  if (TREE_CODE (type) == OFFSET_TYPE)
    component = resolve_offset_ref (component);
  return component;
}

/* Return a tree node for the expression TYPENAME '(' PARMS ')'.  */

tree
build_functional_cast (exp, parms)
     tree exp;
     tree parms;
{
  /* This is either a call to a constructor,
     or a C cast in C++'s `functional' notation.  */
  tree type;

  if (exp == error_mark_node || parms == error_mark_node)
    return error_mark_node;

  if (TREE_CODE (exp) == IDENTIFIER_NODE)
    {
      if (IDENTIFIER_HAS_TYPE_VALUE (exp))
	/* Either an enum or an aggregate type.  */
	type = IDENTIFIER_TYPE_VALUE (exp);
      else
	{
	  type = lookup_name (exp, 1);
	  if (!type || TREE_CODE (type) != TYPE_DECL)
	    {
	      cp_error ("`%T' fails to be a typedef or built-in type", exp);
	      return error_mark_node;
	    }
	  type = TREE_TYPE (type);
	}
    }
  else if (TREE_CODE (exp) == TYPE_DECL)
    type = TREE_TYPE (exp);
  else
    type = exp;

  if (processing_template_decl)
    return build_min (CAST_EXPR, type, parms);

  if (IS_SIGNATURE (type))
    {
      error ("signature type not allowed in cast or constructor expression");
      return error_mark_node;
    }

  if (! IS_AGGR_TYPE (type))
    {
      /* this must build a C cast */
      if (parms == NULL_TREE)
	parms = integer_zero_node;
      else
	{
	  if (TREE_CHAIN (parms) != NULL_TREE)
	    pedwarn ("initializer list being treated as compound expression");
	  parms = build_compound_expr (parms);
	}

      return build_c_cast (type, parms);
    }

  /* Prepare to evaluate as a call to a constructor.  If this expression
     is actually used, for example,
	 
     return X (arg1, arg2, ...);
	 
     then the slot being initialized will be filled in.  */

  if (TYPE_SIZE (complete_type (type)) == NULL_TREE)
    {
      cp_error ("type `%T' is not yet defined", type);
      return error_mark_node;
    }
  if (IS_AGGR_TYPE (type) && CLASSTYPE_ABSTRACT_VIRTUALS (type))
    {
      abstract_virtuals_error (NULL_TREE, type);
      return error_mark_node;
    }

  if (parms && TREE_CHAIN (parms) == NULL_TREE)
    return build_c_cast (type, TREE_VALUE (parms));

  /* We need to zero-initialize POD types.  Let's do that for everything
     that doesn't need a constructor.  */
  if (parms == NULL_TREE && !TYPE_NEEDS_CONSTRUCTING (type)
      && TYPE_HAS_DEFAULT_CONSTRUCTOR (type))
    {
      exp = build (CONSTRUCTOR, type, NULL_TREE, NULL_TREE);
      return get_target_expr (exp);
    }

  exp = build_method_call (NULL_TREE, ctor_identifier, parms,
			   TYPE_BINFO (type), LOOKUP_NORMAL);

  if (exp == error_mark_node)
    return error_mark_node;

  return build_cplus_new (type, exp);
}

/* Return the character string for the name that encodes the
   enumeral value VALUE in the domain TYPE.  */

char *
enum_name_string (value, type)
     tree value;
     tree type;
{
  register tree values = TYPE_VALUES (type);
  register HOST_WIDE_INT intval = TREE_INT_CST_LOW (value);

  my_friendly_assert (TREE_CODE (type) == ENUMERAL_TYPE, 324);
  while (values
	 && TREE_INT_CST_LOW (TREE_VALUE (values)) != intval)
    values = TREE_CHAIN (values);
  if (values == NULL_TREE)
    {
      char *buf = (char *)oballoc (16 + TYPE_NAME_LENGTH (type));

      /* Value must have been cast.  */
      sprintf (buf, "(enum %s)%ld",
	       TYPE_NAME_STRING (type), (long) intval);
      return buf;
    }
  return IDENTIFIER_POINTER (TREE_PURPOSE (values));
}

#if 0
/* Print out a language-specific error message for
   (Pascal) case or (C) switch statements.
   CODE tells what sort of message to print. 
   TYPE is the type of the switch index expression.
   NEW is the new value that we were trying to add.
   OLD is the old value that stopped us from adding it.  */

void
report_case_error (code, type, new_value, old_value)
     int code;
     tree type;
     tree new_value, old_value;
{
  if (code == 1)
    {
      if (new_value)
	error ("case label not within a switch statement");
      else
	error ("default label not within a switch statement");
    }
  else if (code == 2)
    {
      if (new_value == 0)
	{
	  error ("multiple default labels in one switch");
	  return;
	}
      if (TREE_CODE (new_value) == RANGE_EXPR)
	if (TREE_CODE (old_value) == RANGE_EXPR)
	  {
	    char *buf = (char *)alloca (4 * (8 + TYPE_NAME_LENGTH (type)));
	    if (TREE_CODE (type) == ENUMERAL_TYPE)
	      sprintf (buf, "overlapping ranges [%s..%s], [%s..%s] in case expression",
		       enum_name_string (TREE_OPERAND (new_value, 0), type),
		       enum_name_string (TREE_OPERAND (new_value, 1), type),
		       enum_name_string (TREE_OPERAND (old_value, 0), type),
		       enum_name_string (TREE_OPERAND (old_value, 1), type));
	    else
	      sprintf (buf, "overlapping ranges [%d..%d], [%d..%d] in case expression",
		       TREE_INT_CST_LOW (TREE_OPERAND (new_value, 0)),
		       TREE_INT_CST_LOW (TREE_OPERAND (new_value, 1)),
		       TREE_INT_CST_LOW (TREE_OPERAND (old_value, 0)),
		       TREE_INT_CST_LOW (TREE_OPERAND (old_value, 1)));
	    error (buf);
	  }
	else
	  {
	    char *buf = (char *)alloca (4 * (8 + TYPE_NAME_LENGTH (type)));
	    if (TREE_CODE (type) == ENUMERAL_TYPE)
	      sprintf (buf, "range [%s..%s] includes element `%s' in case expression",
		       enum_name_string (TREE_OPERAND (new_value, 0), type),
		       enum_name_string (TREE_OPERAND (new_value, 1), type),
		       enum_name_string (old_value, type));
	    else
	      sprintf (buf, "range [%d..%d] includes (%d) in case expression",
		       TREE_INT_CST_LOW (TREE_OPERAND (new_value, 0)),
		       TREE_INT_CST_LOW (TREE_OPERAND (new_value, 1)),
		       TREE_INT_CST_LOW (old_value));
	    error (buf);
	  }
      else if (TREE_CODE (old_value) == RANGE_EXPR)
	{
	  char *buf = (char *)alloca (4 * (8 + TYPE_NAME_LENGTH (type)));
	  if (TREE_CODE (type) == ENUMERAL_TYPE)
	    sprintf (buf, "range [%s..%s] includes element `%s' in case expression",
		     enum_name_string (TREE_OPERAND (old_value, 0), type),
		     enum_name_string (TREE_OPERAND (old_value, 1), type),
		     enum_name_string (new_value, type));
	  else
	    sprintf (buf, "range [%d..%d] includes (%d) in case expression",
		     TREE_INT_CST_LOW (TREE_OPERAND (old_value, 0)),
		     TREE_INT_CST_LOW (TREE_OPERAND (old_value, 1)),
		     TREE_INT_CST_LOW (new_value));
	  error (buf);
	}
      else
	{
	  if (TREE_CODE (type) == ENUMERAL_TYPE)
	    error ("duplicate label `%s' in switch statement",
		   enum_name_string (new_value, type));
	  else
	    error ("duplicate label (%d) in switch statement",
		   TREE_INT_CST_LOW (new_value));
	}
    }
  else if (code == 3)
    {
      if (TREE_CODE (type) == ENUMERAL_TYPE)
	warning ("case value out of range for enum %s",
		 TYPE_NAME_STRING (type));
      else
	warning ("case value out of range");
    }
  else if (code == 4)
    {
      if (TREE_CODE (type) == ENUMERAL_TYPE)
	error ("range values `%s' and `%s' reversed",
	       enum_name_string (new_value, type),
	       enum_name_string (old_value, type));
      else
	error ("range values reversed");
    }
}
#endif

/* Complain about defining new types in inappropriate places.  We give an
   exception for C-style casts, to accommodate GNU C stylings.  */

void
check_for_new_type (string, inptree)
     const char *string;
     flagged_type_tree inptree;
{
  if (inptree.new_type_flag
      && (pedantic || strcmp (string, "cast") != 0))
    pedwarn ("ANSI C++ forbids defining types within %s",string);
}