The DR#458 is about the usage of ATOMIC_*_LOCK_FREE macros defined in
stdatomic.h in the #if directives. Proposed Technical Corrigendum of
this DR is that these macros should expand to constant expressions
suitable for use in #if preprocessing directives. This patch does
that by mapping these macros to __GCC_ATOMIC_*_LOCK_FREE variants
defined in c-cppbuiltin.c:cpp_atomic_builtins. (It's what libsupc++
does.) The current implementation wouldn't work in #if directives.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2014-08-14 Marek Polacek <pola...@redhat.com>
DR 458
* ginclude/stdatomic.h (__atomic_type_lock_free): Remove.
(ATOMIC_*_LOCK_FREE): Map to __GCC_ATOMIC_*_LOCK_FREE.
* gcc.dg/c11-stdatomic-2.c: New test.
diff --git gcc/ginclude/stdatomic.h gcc/ginclude/stdatomic.h
index 108259b4..26b4b6e 100644
--- gcc/ginclude/stdatomic.h
+++ gcc/ginclude/stdatomic.h
@@ -95,30 +95,16 @@ typedef _Atomic __UINTMAX_TYPE__ atomic_uintmax_t;
#define atomic_signal_fence(MO) __atomic_signal_fence (MO)
#define atomic_is_lock_free(OBJ) __atomic_is_lock_free (sizeof (*(OBJ)), (OBJ))
-#define __atomic_type_lock_free(T) \
- (__atomic_always_lock_free (sizeof (T), (void *) 0) \
- ? 2 \
- : (__atomic_is_lock_free (sizeof (T), (void *) 0) ? 1 : 0))
-#define ATOMIC_BOOL_LOCK_FREE \
- __atomic_type_lock_free (atomic_bool)
-#define ATOMIC_CHAR_LOCK_FREE \
- __atomic_type_lock_free (atomic_char)
-#define ATOMIC_CHAR16_T_LOCK_FREE \
- __atomic_type_lock_free (atomic_char16_t)
-#define ATOMIC_CHAR32_T_LOCK_FREE \
- __atomic_type_lock_free (atomic_char32_t)
-#define ATOMIC_WCHAR_T_LOCK_FREE \
- __atomic_type_lock_free (atomic_wchar_t)
-#define ATOMIC_SHORT_LOCK_FREE \
- __atomic_type_lock_free (atomic_short)
-#define ATOMIC_INT_LOCK_FREE \
- __atomic_type_lock_free (atomic_int)
-#define ATOMIC_LONG_LOCK_FREE \
- __atomic_type_lock_free (atomic_long)
-#define ATOMIC_LLONG_LOCK_FREE \
- __atomic_type_lock_free (atomic_llong)
-#define ATOMIC_POINTER_LOCK_FREE \
- __atomic_type_lock_free (void * _Atomic)
+#define ATOMIC_BOOL_LOCK_FREE __GCC_ATOMIC_BOOL_LOCK_FREE
+#define ATOMIC_CHAR_LOCK_FREE __GCC_ATOMIC_CHAR_LOCK_FREE
+#define ATOMIC_CHAR16_T_LOCK_FREE __GCC_ATOMIC_CHAR16_T_LOCK_FREE
+#define ATOMIC_CHAR32_T_LOCK_FREE __GCC_ATOMIC_CHAR32_T_LOCK_FREE
+#define ATOMIC_WCHAR_T_LOCK_FREE __GCC_ATOMIC_WCHAR_T_LOCK_FREE
+#define ATOMIC_SHORT_LOCK_FREE __GCC_ATOMIC_SHORT_LOCK_FREE
+#define ATOMIC_INT_LOCK_FREE __GCC_ATOMIC_INT_LOCK_FREE
+#define ATOMIC_LONG_LOCK_FREE __GCC_ATOMIC_LONG_LOCK_FREE
+#define ATOMIC_LLONG_LOCK_FREE __GCC_ATOMIC_LLONG_LOCK_FREE
+#define ATOMIC_POINTER_LOCK_FREE __GCC_ATOMIC_POINTER_LOCK_FREE
/* Note that these macros require __typeof__ and __auto_type to remove
diff --git gcc/testsuite/gcc.dg/c11-stdatomic-2.c
gcc/testsuite/gcc.dg/c11-stdatomic-2.c
index e69de29..d746b5c 100644
--- gcc/testsuite/gcc.dg/c11-stdatomic-2.c
+++ gcc/testsuite/gcc.dg/c11-stdatomic-2.c
@@ -0,0 +1,27 @@
+/* Test stdatomic.h header contents. Test that ATOMIC_*_LOCK_FREE
+ macros can be used in an #if directive (DR#458). */
+/* { dg-do preprocess } */
+/* { dg-options "-std=c11 -pedantic-errors" } */
+
+#include <stdatomic.h>
+
+#if ATOMIC_BOOL_LOCK_FREE
+#endif
+#if ATOMIC_CHAR_LOCK_FREE
+#endif
+#if ATOMIC_CHAR16_T_LOCK_FREE
+#endif
+#if ATOMIC_CHAR32_T_LOCK_FREE
+#endif
+#if ATOMIC_WCHAR_T_LOCK_FREE
+#endif
+#if ATOMIC_SHORT_LOCK_FREE
+#endif
+#if ATOMIC_INT_LOCK_FREE
+#endif
+#if ATOMIC_LONG_LOCK_FREE
+#endif
+#if ATOMIC_LLONG_LOCK_FREE
+#endif
+#if ATOMIC_POINTER_LOCK_FREE
+#endif
Marek
