On Fri, 25 Sept 2026 at 18:18, Jason Merrill wrote:
> While we're touching the comments, how about mentioning the C23 changes
> as well?
Good idea. Like so?
-- >8 --
The <stdalign.h> macros were removed from C23 and C++26 but this patch
just tweaks the comment, without actually removing them. Doing so would
technically be a breaking change, but it's not expected that these
macros are widely used.
gcc/ChangeLog:
* ginclude/stdalign.h (__alignas_is_defined, __alignof_is_defined):
Note that the macros were removed in C23 and C++26.
* ginclude/stdbool.h (__bool_true_false_are_defined): Note that
the macro is obsolescent since C23 and deprecated since C++23.
---
gcc/ginclude/stdalign.h | 3 ++-
gcc/ginclude/stdbool.h | 2 ++
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/gcc/ginclude/stdalign.h b/gcc/ginclude/stdalign.h
index a68cb28059ce..fdf016ef3bfe 100644
--- a/gcc/ginclude/stdalign.h
+++ b/gcc/ginclude/stdalign.h
@@ -33,7 +33,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If
not, see
#define alignof _Alignof
#endif
-/* These are defined for C++, but deprecated in C++23. */
+/* Added in C99, removed in C23.
+ Also defined in C++ since C++11, deprecated in C++23 and gone in C++26. */
#define __alignas_is_defined 1
#define __alignof_is_defined 1
diff --git a/gcc/ginclude/stdbool.h b/gcc/ginclude/stdbool.h
index 9070a1876233..a45bd9b7712b 100644
--- a/gcc/ginclude/stdbool.h
+++ b/gcc/ginclude/stdbool.h
@@ -46,6 +46,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If
not, see
#endif /* __cplusplus */
/* Signal that all the definitions are present. */
+/* Added in C99, made obsolescent in C23.
+ Also defined in C++ since C++11, but deprecated in C++23. */
#define __bool_true_false_are_defined 1
#endif /* stdbool.h */
--
2.55.0
