diff mbox

manual: Update _DEFAULT_SOURCE.

Message ID 20180219124531.29958-1-ricaljasan@pacific.net
State Committed
Headers

Commit Message

Rical Jasan Feb. 19, 2018, 12:45 p.m. UTC 
  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.

	* include/features.h: Add _ISOC11_SOURCE to test for whether
	to define _DEFAULT_SOURCE.
	* manual/creature.texi (_DEFAULT_SOURCE): Improve
	documentation.
---
 include/features.h   |  2 +-
 manual/creature.texi | 21 ++++++++++++++-------
 2 files changed, 15 insertions(+), 8 deletions(-)

Comments

Joseph Myers Feb. 19, 2018, 4:14 p.m. UTC | #1 
On Mon, 19 Feb 2018, Rical Jasan wrote:

> 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.

I think this is a header bug that was user-visible in releases, so should 
be filed in Bugzilla before being fixed.
Rical Jasan Feb. 20, 2018, 8:30 a.m. UTC | #2 
On 02/19/2018 08:14 AM, Joseph Myers wrote:
> On Mon, 19 Feb 2018, Rical Jasan wrote:
>> 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.
> 
> I think this is a header bug that was user-visible in releases, so should 
> be filed in Bugzilla before being fixed.

I created BZ #22862. [0]  Should I commit now, with an update to the
commit message/ChangeLog to include the BZ#?

Rical

[0] https://sourceware.org/bugzilla/show_bug.cgi?id=22862
Joseph Myers Feb. 20, 2018, 1:59 p.m. UTC | #3 
On Tue, 20 Feb 2018, Rical Jasan wrote:

> On 02/19/2018 08:14 AM, Joseph Myers wrote:
> > On Mon, 19 Feb 2018, Rical Jasan wrote:
> >> 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.
> > 
> > I think this is a header bug that was user-visible in releases, so should 
> > be filed in Bugzilla before being fixed.
> 
> I created BZ #22862. [0]  Should I commit now, with an update to the
> commit message/ChangeLog to include the BZ#?

Yes, in this case.
Rical Jasan Feb. 21, 2018, 10:49 a.m. UTC | #4 
On 02/20/2018 05:59 AM, Joseph Myers wrote:
> On Tue, 20 Feb 2018, Rical Jasan wrote:
> 
>> On 02/19/2018 08:14 AM, Joseph Myers wrote:
>>> On Mon, 19 Feb 2018, Rical Jasan wrote:
>>>> 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.
>>>
>>> I think this is a header bug that was user-visible in releases, so should 
>>> be filed in Bugzilla before being fixed.
>>
>> I created BZ #22862. [0]  Should I commit now, with an update to the
>> commit message/ChangeLog to include the BZ#?
> 
> Yes, in this case.

Committed: 862b45026fa6; RESOLVED BZ #22862. [0]

Thanks,
Rical

[0] https://sourceware.org/bugzilla/show_bug.cgi?id=22862
diff mbox

Patch

diff --git a/include/features.h b/include/features.h
index 137a90b405..d22c32eee6 100644
--- a/include/features.h
+++ b/include/features.h
@@ -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
diff --git a/manual/creature.texi b/manual/creature.texi
index fe7a7790a2..8876b2ab77 100644
--- a/manual/creature.texi
+++ b/manual/creature.texi
@@ -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