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.
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_direct_declarator_inner): Record whether
_Alignas has been seen.
* c-decl.c (build_array_declarator): Add alignas_p parameter. Warn
if _Alignas occurs in an array declarator.
* c-tree.h (build_array_declarator): Adjust declaration.
testsuite/
* gcc.dg/c1x-align-5.c: New test.
--- gcc/c/c-tree.h.mp 2013-10-15 19:36:09.548670833 +0200
+++ gcc/c/c-tree.h 2013-10-15 19:36:25.003727398 +0200
@@ -480,8 +480,8 @@ extern void c_init_decl_processing (void
extern void c_print_identifier (FILE *, tree, int);
extern int quals_from_declspecs (const struct c_declspecs *);
extern struct c_declarator *build_array_declarator (location_t, tree,
- struct c_declspecs *,
- bool, bool);
+ struct c_declspecs *,
+ bool, bool, bool);
extern tree build_enumerator (location_t, location_t, struct c_enum_contents *,
tree, tree);
extern tree check_for_loop_decls (location_t, bool);
--- gcc/c/c-parser.c.mp 2013-10-15 19:33:47.706150200 +0200
+++ gcc/c/c-parser.c 2013-10-15 19:35:57.557627164 +0200
@@ -3096,8 +3096,10 @@ c_parser_direct_declarator_inner (c_pars
struct c_declspecs *quals_attrs = build_null_declspecs ();
bool static_seen;
bool star_seen;
+ bool alignas_seen;
tree dimen;
c_parser_consume_token (parser);
+ alignas_seen = c_parser_next_token_is_keyword (parser, RID_ALIGNAS);
c_parser_declspecs (parser, quals_attrs, false, false, true,
cla_prefer_id);
static_seen = c_parser_next_token_is_keyword (parser, RID_STATIC);
if (static_seen)
@@ -3169,7 +3171,8 @@ c_parser_direct_declarator_inner (c_pars
if (dimen)
mark_exp_read (dimen);
declarator = build_array_declarator (brace_loc, dimen, quals_attrs,
- static_seen, star_seen);
+ static_seen, star_seen,
+ alignas_seen);
if (declarator == NULL)
return NULL;
inner = set_array_declarator_inner (declarator, inner);
--- gcc/c/c-decl.c.mp 2013-10-15 19:35:30.172525717 +0200
+++ gcc/c/c-decl.c 2013-10-16 11:05:06.046383071 +0200
@@ -3866,7 +3866,7 @@ quals_from_declspecs (const struct c_dec
struct c_declarator *
build_array_declarator (location_t loc,
tree expr, struct c_declspecs *quals, bool static_p,
- bool vla_unspec_p)
+ bool vla_unspec_p, bool alignas_p)
{
struct c_declarator *declarator = XOBNEW (&parser_obstack,
struct c_declarator);
@@ -3908,6 +3908,9 @@ build_array_declarator (location_t loc,
}
current_scope->had_vla_unspec = true;
}
+ if (alignas_p)
+ pedwarn (loc, OPT_Wpedantic, "%<_Alignas%> meaningless in array "
+ "declarator");
return declarator;
}
--- gcc/testsuite/gcc.dg/c1x-align-5.c.mp 2013-10-16 11:11:16.432690963
+0200
+++ gcc/testsuite/gcc.dg/c1x-align-5.c 2013-10-16 11:15:09.269514593 +0200
@@ -0,0 +1,17 @@
+/* Test C1X alignment support. Test invalid code. */
+/* { dg-do compile } */
+/* { dg-options "-std=c1x -pedantic-errors" } */
+
+static int
+foo (int a[_Alignas (0) 10]) /* { dg-error "meaningless in array declarator"
} */
+{
+ return a[0];
+}
+
+int
+main ()
+{
+ int a[_Alignas (int) 10]; /* { dg-error "meaningless in array declarator"
} */
+ foo (a);
+ return 0;
+}
Marek
