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| author | Zack Weinberg <zackw@panix.com> | 2016-12-06 10:14:42 -0500 |
|---|---|---|
| committer | Zack Weinberg <zackw@panix.com> | 2016-12-08 15:45:33 -0500 |
| commit | c03073774f915fe7841c2b551fe304544143470f (patch) | |
| tree | 724d0dff62918aba70b4e4fc17c80f35f2e6eafa /NEWS | |
| parent | 3d6bfcace17a479c2e006a33567af80e6070583f (diff) | |
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Make _REENTRANT and _THREAD_SAFE aliases for _POSIX_C_SOURCE=199506L.
For many years, the only effect of these macros has been to make
unistd.h declare getlogin_r. _POSIX_C_SOURCE >= 199506L also causes
this function to be declared. However, people who don't carefully
read all the headers might be confused into thinking they need to
define _REENTRANT for any threaded code (as was indeed the case a long
time ago).
Therefore, remove __USE_REENTRANT, and make _REENTRANT and _THREAD_SAFE
into synonyms for _POSIX_C_SOURCE=199506L. This will only affect
programs that don't select a higher conformance level some other way.
For instance, -std=c89 -D_REENTRANT will see a change in visible
declarations, but -std=c99 -D_POSIX_C_SOURCE=200809L -D_REENTRANT won't,
and -D_REENTRANT all by itself also won't, because _DEFAULT_SOURCE
implies _POSIX_C_SOURCE > 199506.
* include/features.h: Remove __USE_REENTRANT. Treat _REENTRANT
and _THREAD_SAFE the same as _POSIX_C_SOURCE=199506L, if a higher
POSIX conformance level has not been selected by other macros.
* NEWS, manual/creature.texi: Document this change.
* posix/unistd.h, posix/bits/unistd.h: Don't check __USE_REENTRANT.
* include/libc-symbols.h: Don't define _REENTRANT.
* scripts/check-installed-headers.sh: Don't undefine _REENTRANT.
Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 13 |
1 files changed, 13 insertions, 0 deletions
@@ -22,6 +22,19 @@ Version 2.25 from that TS. Note that most features from that TS are not supported by the GNU C Library. +* The nonstandard feature selection macros _REENTRANT and _THREAD_SAFE are + now treated as compatibility synonyms for _POSIX_C_SOURCE=199506L. + Since the GNU C Library defaults to a much newer revision of POSIX, this + will only affect programs that specifically request an old conformance + mode. For instance, a program compiled with -std=c89 -D_REENTRANT will + see a change in the visible declarations, but a program compiled with + just -D_REENTRANT, or -std=c99 -D_POSIX_C_SOURCE=200809L -D_REENTRANT, + will not. + + Some C libraries once required _REENTRANT and/or _THREAD_SAFE to be + defined by all multithreaded code, but glibc has not required this for + many years. + * The inclusion of <sys/sysmacros.h> by <sys/types.h> is deprecated. This means that in a future release, the macros “major”, “minor”, and “makedev” will only be available from <sys/sysmacros.h>. |