struct obstack *);
static tree c_parser_compound_statement (c_parser *, location_t * = NULL);
static location_t c_parser_compound_statement_nostart (c_parser *);
-static void c_parser_label (c_parser *);
+static void c_parser_label (c_parser *, tree);
static void c_parser_statement (c_parser *, bool *, location_t * = NULL);
static void c_parser_statement_after_labels (c_parser *, bool *,
vec<tree> * = NULL);
}
/* Parse a compound statement (possibly a function body) (C90 6.6.2,
- C99 6.8.2, C11 6.8.2).
+ C99 6.8.2, C11 6.8.2, C2X 6.8.2).
compound-statement:
{ block-item-list[opt] }
block-item-list block-item
block-item:
+ label
nested-declaration
statement
{
location_t loc = c_parser_peek_token (parser)->location;
loc = expansion_point_location_if_in_system_header (loc);
- /* Standard attributes may start a statement or a declaration. */
+ /* Standard attributes may start a label, statement or declaration. */
bool have_std_attrs
= c_parser_nth_token_starts_std_attributes (parser, 1);
tree std_attrs = NULL_TREE;
|| (c_parser_next_token_is (parser, CPP_NAME)
&& c_parser_peek_2nd_token (parser)->type == CPP_COLON))
{
- c_warn_unused_attributes (std_attrs);
if (c_parser_next_token_is_keyword (parser, RID_CASE))
label_loc = c_parser_peek_2nd_token (parser)->location;
else
last_label = true;
last_stmt = false;
mark_valid_location_for_stdc_pragma (false);
- c_parser_label (parser);
+ c_parser_label (parser, std_attrs);
}
- else if (!last_label
- && (c_parser_next_tokens_start_declaration (parser)
- || (have_std_attrs
- && c_parser_next_token_is (parser, CPP_SEMICOLON))))
+ else if (c_parser_next_tokens_start_declaration (parser)
+ || (have_std_attrs
+ && c_parser_next_token_is (parser, CPP_SEMICOLON)))
{
- last_label = false;
+ if (last_label)
+ pedwarn_c11 (c_parser_peek_token (parser)->location, OPT_Wpedantic,
+ "a label can only be part of a statement and "
+ "a declaration is not a statement");
+
mark_valid_location_for_stdc_pragma (false);
bool fallthru_attr_p = false;
c_parser_declaration_or_fndef (parser, true, !have_std_attrs,
true, true, true, NULL,
vNULL, have_std_attrs, std_attrs,
NULL, &fallthru_attr_p);
+
if (last_stmt && !fallthru_attr_p)
pedwarn_c90 (loc, OPT_Wdeclaration_after_statement,
"ISO C90 forbids mixed declarations and code");
last_stmt = fallthru_attr_p;
+ last_label = false;
}
- else if (!last_label
- && c_parser_next_token_is_keyword (parser, RID_EXTENSION))
+ else if (c_parser_next_token_is_keyword (parser, RID_EXTENSION))
{
/* __extension__ can start a declaration, but is also an
unary operator that can start an expression. Consume all
parser->error = false;
}
if (last_label)
- error_at (label_loc, "label at end of compound statement");
+ pedwarn_c11 (label_loc, OPT_Wpedantic, "label at end of compound statement");
location_t endloc = c_parser_peek_token (parser)->location;
c_parser_consume_token (parser);
/* Restore the value we started with. */
static void
c_parser_all_labels (c_parser *parser)
{
+ tree std_attrs = NULL;
if (c_parser_nth_token_starts_std_attributes (parser, 1))
{
- tree std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ std_attrs = c_parser_std_attribute_specifier_sequence (parser);
if (c_parser_next_token_is (parser, CPP_SEMICOLON))
c_parser_error (parser, "expected statement");
- else
- c_warn_unused_attributes (std_attrs);
}
while (c_parser_next_token_is_keyword (parser, RID_CASE)
|| c_parser_next_token_is_keyword (parser, RID_DEFAULT)
|| (c_parser_next_token_is (parser, CPP_NAME)
&& c_parser_peek_2nd_token (parser)->type == CPP_COLON))
- c_parser_label (parser);
+ {
+ c_parser_label (parser, std_attrs);
+ std_attrs = NULL;
+ if (c_parser_nth_token_starts_std_attributes (parser, 1))
+ {
+ std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ if (c_parser_next_token_is (parser, CPP_SEMICOLON))
+ c_parser_error (parser, "expected statement");
+ }
+ }
+ if (std_attrs)
+ c_warn_unused_attributes (std_attrs);
}
/* Parse a label (C90 6.6.1, C99 6.8.1, C11 6.8.1).
in the caller, to distinguish statements from declarations. Any
attribute-specifier-sequence after the label is parsed in this
function. */
-
static void
-c_parser_label (c_parser *parser)
+c_parser_label (c_parser *parser, tree std_attrs)
{
location_t loc1 = c_parser_peek_token (parser)->location;
tree label = NULL_TREE;
if (tlab)
{
decl_attributes (&tlab, attrs, 0);
+ decl_attributes (&tlab, std_attrs, 0);
label = add_stmt (build_stmt (loc1, LABEL_EXPR, tlab));
}
+ if (attrs
+ && c_parser_next_tokens_start_declaration (parser))
+ warning_at (loc2, OPT_Wattributes, "GNU-style attribute between"
+ " label and declaration appertains to the label");
}
if (label)
{
FALLTHROUGH_LABEL_P (LABEL_EXPR_LABEL (label)) = fallthrough_p;
else
FALLTHROUGH_LABEL_P (CASE_LABEL (label)) = fallthrough_p;
-
- /* Standard attributes are only allowed here if they start a
- statement, not a declaration (including the case of an
- attribute-declaration with only attributes). */
- bool have_std_attrs
- = c_parser_nth_token_starts_std_attributes (parser, 1);
- tree std_attrs = NULL_TREE;
- if (have_std_attrs)
- std_attrs = c_parser_std_attribute_specifier_sequence (parser);
-
- /* Allow '__attribute__((fallthrough));'. */
- if (!have_std_attrs
- && c_parser_next_token_is_keyword (parser, RID_ATTRIBUTE))
- {
- location_t loc = c_parser_peek_token (parser)->location;
- tree attrs = c_parser_gnu_attributes (parser);
- if (attribute_fallthrough_p (attrs))
- {
- if (c_parser_next_token_is (parser, CPP_SEMICOLON))
- {
- tree fn = build_call_expr_internal_loc (loc,
- IFN_FALLTHROUGH,
- void_type_node, 0);
- add_stmt (fn);
- }
- else
- warning_at (loc, OPT_Wattributes, "%<fallthrough%> attribute "
- "not followed by %<;%>");
- }
- else if (attrs != NULL_TREE)
- warning_at (loc, OPT_Wattributes, "only attribute %<fallthrough%>"
- " can be applied to a null statement");
- }
- if (c_parser_next_tokens_start_declaration (parser)
- || (have_std_attrs
- && c_parser_next_token_is (parser, CPP_SEMICOLON)))
- {
- error_at (c_parser_peek_token (parser)->location,
- "a label can only be part of a statement and "
- "a declaration is not a statement");
- c_parser_declaration_or_fndef (parser, /*fndef_ok*/ false,
- /*static_assert_ok*/ true,
- /*empty_ok*/ true, /*nested*/ true,
- /*start_attr_ok*/ true, NULL,
- vNULL, have_std_attrs, std_attrs);
- }
- else if (std_attrs)
- /* Nonempty attributes on the following statement are ignored. */
- c_warn_unused_attributes (std_attrs);
}
}
* Designated Inits:: Labeling elements of initializers.
* Case Ranges:: `case 1 ... 9' and such.
* Cast to Union:: Casting to union type from any member of the union.
-* Mixed Declarations:: Mixing declarations and code.
+* Mixed Labels and Declarations:: Mixing declarations, labels and code.
* Function Attributes:: Declaring that functions have no side effects,
or that they can never return.
* Variable Attributes:: Specifying attributes of variables.
hack ((union foo) x);
@end smallexample
-@node Mixed Declarations
-@section Mixed Declarations and Code
+@node Mixed Labels and Declarations
+@section Mixed Declarations, Labels and Code
@cindex mixed declarations and code
@cindex declarations, mixed with code
@cindex code, mixed with declarations
ISO C99 and ISO C++ allow declarations and code to be freely mixed
-within compound statements. As an extension, GNU C also allows this in
-C90 mode. For example, you could do:
+within compound statements. ISO C2X allows labels to be
+placed before declarations and at the end of a compound statement.
+As an extension, GNU C also allows all this in C90 mode. For example,
+you could do:
@smallexample
int i;
available for functions (@pxref{Function Attributes}), variables
(@pxref{Variable Attributes}), enumerators (@pxref{Enumerator Attributes}),
statements (@pxref{Statement Attributes}), and for types
-(@pxref{Type Attributes}).
+(@pxref{Type Attributes}). A label attribute followed
+by a declaration appertains to the label and not the declaration.
This example uses the @code{cold} label attribute to indicate the
@code{ErrorHandling} branch is unlikely to be taken and that the
projects / gcc.git / commitdiff