manual: Update _DEFAULT_SOURCE. [BZ #22862]

The description of the interplay between feature test macros and
compiler options in the description of _DEFAULT_SOURCE is a little
confusing, and dated, so clarify the situation, and don't assume a
specific value for _DEFAULT_SOURCE.

Also, _DEFAULT_SOURCE is supposed to be defined if none of the C/POSIX
feature test macros are defined, but the condition was lacking a test
for _ISOC11_SOURCE, so that is also addressed.

	[BZ #22862]
	* include/features.h: Add _ISOC11_SOURCE to test for whether
	to define _DEFAULT_SOURCE.
	* manual/creature.texi (_DEFAULT_SOURCE): Improve
	documentation.
This commit is contained in:
Rical Jasan 2018-02-19 04:37:16 -08:00
parent 999a6dab3e
commit 862b45026f
3 changed files with 22 additions and 8 deletions

View file

@ -1,3 +1,10 @@
2018-02-21 Rical Jasan <ricaljasan@pacific.net>
[BZ #22862]
* include/features.h: Add _ISOC11_SOURCE to test for whether to
define _DEFAULT_SOURCE.
* manual/creature.texi (_DEFAULT_SOURCE): Improve documentation.
2018-02-21 Florian Weimer <fweimer@redhat.com>
[BZ #20890]

View file

@ -214,7 +214,7 @@
define _DEFAULT_SOURCE. */
#if (defined _DEFAULT_SOURCE \
|| (!defined __STRICT_ANSI__ \
&& !defined _ISOC99_SOURCE \
&& !defined _ISOC99_SOURCE && !defined _ISOC11_SOURCE \
&& !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE \
&& !defined _XOPEN_SOURCE))
# undef _DEFAULT_SOURCE

View file

@ -221,13 +221,20 @@ precedence.
If you define this macro, most features are included apart from
X/Open, LFS and GNU extensions: the effect is to enable features from
the 2008 edition of POSIX, as well as certain BSD and SVID features
without a separate feature test macro to control them. Defining this
macro, on its own and without using compiler options such as
@option{-ansi} or @option{-std=c99}, has the same effect as not
defining any feature test macros; defining it together with other
feature test macros, or when options such as @option{-ansi} are used,
enables those features even when the other options would otherwise
cause them to be disabled.
without a separate feature test macro to control them.
Be aware that compiler options also affect included features:
@itemize
@item
If you use a strict conformance option, features beyond those from the
compiler's language version will be disabled, though feature test
macros may be used to enable them.
@item
Features enabled by compiler options are not overridden by feature
test macros.
@end itemize
@end defvr
@defvr Macro _ATFILE_SOURCE