On Wed, Oct 16, 2013 at 12:28:32PM +0000, Joseph S. Myers wrote:
> On Wed, 16 Oct 2013, Marek Polacek wrote:
>
> > This PR is about _Alignas in contexts like
> > char x[_Alignas (int) 20];
> > C grammar does not allow _Alignas to be in an array declarator, yet we
> > don't issue any warning or an error. This patch implements a pedwarn
> > for this. I'm however highly unsure whether we want pedwarn, error, or
> > normal warning for this - currently we just DTRT and ignore the
> > _Alignas altogether.
>
> I think this should be an error.
Makes sense.
> I see this as a problem with how the parsing of array declarators uses
> c_parser_declspecs to parse a sequence of qualifiers and attributes, with
> scspec_ok=false and typespec_ok=false to ensure those kinds of specifiers
> can't occur in the list, but without any measure to exclude alignment
> specifiers. That is, I think c_parser_declspecs should gain an argument
> specifying whether alignment specifiers are OK, and the relevant calls
> from c_parser_direct_declarator_inner would pass false for that argument,
> and uses of alignment specifiers here would result in parse errors.
Thanks, should be done in the attached patch.
> (Incidentally, the comments in c-parser.c that are supposed to give the
> grammar accepted are missing the syntax of array-declarator.)
I've fixed that up.
> I think this should also be tested after "static" (given that there are
> two separate calls to c_parser_declspecs involved), as well as in an
> abstract declarator.
Done.
Regtested/bootstrapped on x86_64-linux, ok for trunk?
2013-10-16 Marek Polacek <pola...@redhat.com>
PR c/58267
c/
* c-parser.c (c_parser_declspecs): Add alignspec_ok parameter.
Document syntax of the array-declarator.
(c_parser_declspecs) <RID_ALIGNAS>: Bail out if alignment specs
are not permitted.
(c_parser_declaration_or_fndef): Adjust c_parser_declspecs call.
(c_parser_struct_declaration): Likewise.
(c_parser_declarator): Likewise.
(c_parser_direct_declarator_inner): Likewise.
(c_parser_parameter_declaration): Likewise.
(c_parser_type_name): Likewise.
testsuite/
* gcc.dg/c1x-align-5.c: New test.
--- gcc/c/c-parser.c.mp 2013-10-16 15:00:36.774530501 +0200
+++ gcc/c/c-parser.c 2013-10-16 16:31:30.731611508 +0200
@@ -1124,7 +1124,7 @@ static void c_parser_declaration_or_fnde
static void c_parser_static_assert_declaration_no_semi (c_parser *);
static void c_parser_static_assert_declaration (c_parser *);
static void c_parser_declspecs (c_parser *, struct c_declspecs *, bool, bool,
- bool, enum c_lookahead_kind);
+ bool, bool, enum c_lookahead_kind);
static struct c_typespec c_parser_enum_specifier (c_parser *);
static struct c_typespec c_parser_struct_or_union_specifier (c_parser *);
static tree c_parser_struct_declaration (c_parser *);
@@ -1494,7 +1494,8 @@ c_parser_declaration_or_fndef (c_parser
fndef_ok = !nested;
}
- c_parser_declspecs (parser, specs, true, true, start_attr_ok,
cla_nonabstract_decl);
+ c_parser_declspecs (parser, specs, true, true, start_attr_ok,
+ true, cla_nonabstract_decl);
if (parser->error)
{
c_parser_skip_to_end_of_block_or_statement (parser);
@@ -1942,8 +1943,9 @@ c_parser_static_assert_declaration_no_se
/* Parse some declaration specifiers (possibly none) (C90 6.5, C99
6.7), adding them to SPECS (which may already include some).
Storage class specifiers are accepted iff SCSPEC_OK; type
- specifiers are accepted iff TYPESPEC_OK; attributes are accepted at
- the start iff START_ATTR_OK.
+ specifiers are accepted iff TYPESPEC_OK; alignment specifiers are
+ accepted iff ALIGNSPEC_OK; attributes are accepted at the start
+ iff START_ATTR_OK.
declaration-specifiers:
storage-class-specifier declaration-specifiers[opt]
@@ -2039,7 +2041,7 @@ c_parser_static_assert_declaration_no_se
static void
c_parser_declspecs (c_parser *parser, struct c_declspecs *specs,
bool scspec_ok, bool typespec_ok, bool start_attr_ok,
- enum c_lookahead_kind la)
+ bool alignspec_ok, enum c_lookahead_kind la)
{
bool attrs_ok = start_attr_ok;
bool seen_type = specs->typespec_kind != ctsk_none;
@@ -2235,6 +2237,8 @@ c_parser_declspecs (c_parser *parser, st
declspecs_add_attrs (loc, specs, attrs);
break;
case RID_ALIGNAS:
+ if (!alignspec_ok)
+ goto out;
align = c_parser_alignas_specifier (parser);
declspecs_add_alignas (loc, specs, align);
break;
@@ -2640,7 +2644,8 @@ c_parser_struct_declaration (c_parser *p
}
specs = build_null_declspecs ();
decl_loc = c_parser_peek_token (parser)->location;
- c_parser_declspecs (parser, specs, false, true, true, cla_nonabstract_decl);
+ c_parser_declspecs (parser, specs, false, true, true,
+ true, cla_nonabstract_decl);
if (parser->error)
return NULL_TREE;
if (!specs->declspecs_seen_p)
@@ -2888,6 +2893,12 @@ c_parser_alignas_specifier (c_parser * p
type-qualifier-list type-qualifier
type-qualifier-list attributes
+ array-declarator:
+ [ type-qualifier-list[opt] assignment-expression[opt] ]
+ [ static type-qualifier-list[opt] assignment-expression ]
+ [ type-qualifier-list static assignment-expression ]
+ [ type-qualifier-list[opt] * ]
+
parameter-type-list:
parameter-list
parameter-list , ...
@@ -2946,7 +2957,8 @@ c_parser_declarator (c_parser *parser, b
struct c_declspecs *quals_attrs = build_null_declspecs ();
struct c_declarator *inner;
c_parser_consume_token (parser);
- c_parser_declspecs (parser, quals_attrs, false, false, true,
cla_prefer_id);
+ c_parser_declspecs (parser, quals_attrs, false, false, true,
+ true, cla_prefer_id);
inner = c_parser_declarator (parser, type_seen_p, kind, seen_id);
if (inner == NULL)
return NULL;
@@ -3098,12 +3110,14 @@ c_parser_direct_declarator_inner (c_pars
bool star_seen;
tree dimen;
c_parser_consume_token (parser);
- c_parser_declspecs (parser, quals_attrs, false, false, true,
cla_prefer_id);
+ c_parser_declspecs (parser, quals_attrs, false, false, true,
+ false, cla_prefer_id);
static_seen = c_parser_next_token_is_keyword (parser, RID_STATIC);
if (static_seen)
c_parser_consume_token (parser);
if (static_seen && !quals_attrs->declspecs_seen_p)
- c_parser_declspecs (parser, quals_attrs, false, false, true,
cla_prefer_id);
+ c_parser_declspecs (parser, quals_attrs, false, false, true,
+ false, cla_prefer_id);
if (!quals_attrs->declspecs_seen_p)
quals_attrs = NULL;
/* If "static" is present, there must be an array dimension.
@@ -3406,7 +3420,8 @@ c_parser_parameter_declaration (c_parser
declspecs_add_attrs (input_location, specs, attrs);
attrs = NULL_TREE;
}
- c_parser_declspecs (parser, specs, true, true, true, cla_nonabstract_decl);
+ c_parser_declspecs (parser, specs, true, true, true, true,
+ cla_nonabstract_decl);
finish_declspecs (specs);
pending_xref_error ();
prefix_attrs = specs->attrs;
@@ -3715,7 +3730,8 @@ c_parser_type_name (c_parser *parser)
struct c_declarator *declarator;
struct c_type_name *ret;
bool dummy = false;
- c_parser_declspecs (parser, specs, false, true, true, cla_prefer_type);
+ c_parser_declspecs (parser, specs, false, true, true, false,
+ cla_prefer_type);
if (!specs->declspecs_seen_p)
{
c_parser_error (parser, "expected specifier-qualifier-list");
--- gcc/testsuite/gcc.dg/c1x-align-5.c.mp 2013-10-16 16:15:09.704916186
+0200
+++ gcc/testsuite/gcc.dg/c1x-align-5.c 2013-10-16 16:27:50.920786400 +0200
@@ -0,0 +1,20 @@
+/* Test C1X alignment support. Test invalid code. */
+/* { dg-do compile } */
+/* { dg-options "-std=c1x -pedantic-errors" } */
+
+void foo (int []);
+void bar1 (int [_Alignas (double) 10]); /* { dg-error "expected expression
before" } */
+void bar2 (int [static _Alignas (double) 10]); /* { dg-error "expected
expression before" } */
+void bar3 (int [static const _Alignas (double) 10]); /* { dg-error "expected
expression before" } */
+void bar4 (int [const _Alignas (double) 10]); /* { dg-error "expected
expression before" } */
+void bar5 (int [_Alignas (0) *]); /* { dg-error "expected expression before" }
*/
+
+void foo (int a[_Alignas (0) 10]) { } /* { dg-error "expected expression
before" } */
+
+void
+test (void)
+{
+ int a[_Alignas (int) 10]; /* { dg-error "expected expression before" } */
+ int b[10];
+ foo (b);
+}
Marek
