Do not define static_assert or thread_local in headers for C2x

C2x makes static_assert and thread_local into keywords, removing the
definitions as macros in assert.h and threads.h.  Thus, disable those
macros in those glibc headers for C2x.

The disabling is done based on a combination of language version and
__GNUC_PREREQ, *not* based on __GLIBC_USE (ISOC2X), on the principle
that users of the header (when requesting C11 or later APIs - not
assert.h for C99 and older API versions) should always have the names
static_assert or thread_local available after inclusion of the header,
whether as a keyword or as a macro.  Thus, when using a compiler
without the keywords (whether an older compiler, possibly in C2x mode,
or _GNU_SOURCE with any compiler but in an older language mode, for
example) the macros should be defined, even when C2x APIs have been
requested.  The __GNUC_PREREQ conditionals here may well need updating
with the versions of other compilers that gained support for these
keywords in C2x mode.

Tested for x86_64.
This commit is contained in:
Joseph Myers 2022-09-07 18:39:28 +00:00
parent 89d40cacd0
commit b8cc607f3c
2 changed files with 8 additions and 2 deletions

View File

@ -135,7 +135,11 @@ __END_DECLS
#endif /* NDEBUG. */
#if defined __USE_ISOC11 && !defined __cplusplus
#if (defined __USE_ISOC11 \
&& (!defined __STDC_VERSION__ \
|| __STDC_VERSION__ <= 201710L \
|| !__GNUC_PREREQ (13, 0)) \
&& !defined __cplusplus)
# undef static_assert
# define static_assert _Static_assert
#endif

View File

@ -27,7 +27,9 @@ __BEGIN_DECLS
#include <bits/thread-shared-types.h>
#include <bits/types/struct_timespec.h>
#ifndef __cplusplus
#if (!defined __STDC_VERSION__ \
|| __STDC_VERSION__ <= 201710L \
|| !__GNUC_PREREQ (13, 0)) && !defined __cplusplus
# define thread_local _Thread_local
#endif