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 patch ensures that the C99 and C11 features required by C++ are
defined according to the value of the __cplusplus macro, and not just
because G++ always defines _GNU_SOURCE. This will allow G++ to stop
defining _GNU_SOURCE some day, without causing the C99 and C11
interfaces to disappear for C++ programs.
[BZ #21326]
* include/features.h [__cplusplus >= 201103] (__USE_ISOC99): Define.
[__cplusplus >= 201703] (__USE_ISOCXX17, __USE_ISOC11): Define.
* math/Makefile (test-math-cxx11): New test.
* math/test-math-cxx11.cc: New file.
This macro is defined by TS 18661-3 for supporting the _FloatN and
_FloatNx types, as well as the functions suffixed with fN.
* bits/libc-header-start.h:
(__GLIBC_USE_IEC_60559_TYPES_EXT): New macro.
* include/features.h: Describe __STDC_WANT_IEC_60559_TYPES_EXT__.
* manual/creature.texi: Likewise.
gets has the dubious honor of being the only C89 library feature that
has been completely removed from the current C and C++ standards.
glibc follows suit by not declaring it in _GNU_SOURCE mode either,
but it remains present in older compatibility modes. Internally,
two test cases need to see stdio.h make the declaration, but all our
internal code is of course compiled under _GNU_SOURCE. This is currently
kludged by duplicating the gets declaration, fortify wrapper and all,
in include/stdio.h. Also, the conditional in the public headers for
deciding when to declare gets is complicated and repeated in two places.
This patch adds a new macro to features.h that encapsulates the
complicated rule for when to declare gets. stdio.h and bits/stdio2.h
then simply test __GLIBC_USE (DEPRECATED_GETS), and instead of having
a duplicate gets declaration in include/stdio.h, debug/tst-chk1.c and
stdio-common/tst-gets.c can force gets to be declared.
* include/features.h (__GLIBC_USE_DEPRECATED_GETS): New macro.
* libio/stdio.h, libio/bits/stdio2.h: Condition gets on
__GLIBC_USE (DEPRECATED_GETS). Update comments to indicate
gets was removed from C++ in C++14.
* include/stdio.h: Remove redundant declaration of gets.
* debug/tst-chk1.c, stdio-common/tst-gets.c: Force gets to
be declared, since we are testing it.
* stdio-common/Makefile (tst-gets.c): Compile with
-Wno-deprecated-declarations.
* debug/Makefile (tst-chk1.c, tst-chk2.c, tst-chk3.c, tst-chk4.cc)
(tst-chk5.cc, tst-chk6.cc, tst-lfschk1.c, tst-lfschk2.c)
(tst-lfschk3.c, tst-lfschk4.cc, tst-lfschk5.cc, tst-lfschk6.cc):
Compile with -Wno-deprecated-declarations.
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.
This patch implements support for the
__STDC_WANT_IEC_60559_FUNCS_EXT__ feature test macro, following the
__GLIBC_USE approach used for other ISO C feature test macros.
Currently this only affects the exp10 functions (which glibc has had
for a long time).
Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch).
* bits/libc-header-start.h (__GLIBC_USE_IEC_60559_FUNCS_EXT): New
macro.
* include/features.h (__STDC_WANT_IEC_60559_FUNCS_EXT__):
Document.
* manual/creature.texi (__STDC_WANT_IEC_60559_FUNCS_EXT__):
Document macro.
* manual/math.texi (exp10): Document as ISO from TS 18661-4:2015.
(exp10f): Likewise.
(exp10l): Likewise.
* math/bits/mathcalls.h (exp10): Declare if
[__GLIBC_USE (IEC_60559_FUNCS_EXT)], not [__USE_GNU].
There are three new macros added to features.h and sys/cdefs.h:
* __glibc_clang_prereq: just like __GNUC_PREREQ, but for clang.
* __glibc_clang_has_extension: wraps clang's intrinsic __has_extension.
Writing "#if defined __clang__ && __has_extension (...)" doesn't work,
because compilers other than clang will object to the unknown macro
__has_extension even though they don't need to evaluate it.
Instead, write "#if __glibc_clang_has_extension (...)".
* __attribute_deprecated_msg__(msg): like __attribute_deprecated__, but
if possible, prints a message.
The first two are used to define the third. The third will be used
in subsequent patches.
* include/features.h (__glibc_clang_prereq): New macro.
* misc/sys/cdefs.h (__glibc_clang_has_extension)
(__attribute_deprecated_msg__): New macros.
This patch implements support for the __STDC_WANT_IEC_60559_BFP_EXT__
feature test macro from ISO/IEC 18661-1:2014, following the
__GLIBC_USE approach now used for __STDC_WANT_LIB_EXT2__. For this
macro, the relevant consideration is whether it is defined or
undefined when an affected header is included (not what its value is
if defined, and not whether it's defined or undefined when any other
unaffected system header is included).
Currently this macro only affects the issignaling macro and the nextup
and nextdown functions (so they can be enabled by defining this macro,
not just by defining _GNU_SOURCE as previously). Any further features
from this TS added in future would also be conditioned on this macro.
Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch).
* bits/libc-header-start.h (__GLIBC_USE_IEC_60559_BFP_EXT): New
macro.
* include/features.h (__STDC_WANT_IEC_60559_BFP_EXT__): Document.
* manual/arith.texi (issignaling): Document as ISO from TS
18661-1:2014.
(nextup): Likewise.
(nextupf): Likewise.
(nextupl): Likewise.
(nextdown): Likewise.
(nextdownf): Likewise.
(nextdownl): Likewise.
* manual/creature.texi (__STDC_WANT_IEC_60559_BFP_EXT__): Document
macro.
* math/math.h: Define
__GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION and include
<bits/libc-header-start.h> instead of including <features.h>.
(issignaling): Define if [__GLIBC_USE (IEC_60559_BFP_EXT)], not
[__USE_GNU].
* math/bits/mathcalls.h (nextdown): Declare if
[__GLIBC_USE (IEC_60559_BFP_EXT)], not [__USE_GNU].
(nextup): Likewise.
(__issignaling): Likewise.
This patch implements support for the __STDC_WANT_LIB_EXT2__ feature
test macro from ISO/IEC TR 24731-2:2010, thereby implementing one
possible approach for supporting ISO C feature test macros.
Recall that, as described in
<https://sourceware.org/ml/libc-alpha/2016-05/msg00486.html>, these
macros work based on the definition when affected headers are
included, so cannot be handled once when the first system header is
included because that might not be one of the headers the particular
macro in question affects.
<https://sourceware.org/ml/libc-alpha/2016-05/msg00680.html> expresses
views on possible approaches for implementation and
<https://sourceware.org/ml/libc-alpha/2016-06/msg00039.html> follows
up on that.
This patch arranges things so that the relevant condition is
__GLIBC_USE (LIB_EXT2), following one of the suggestions given.
Headers using these macros include <bits/libc-header-start.h>, which
in turn includes <features.h>. Headers must define
__GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION before including
<bits/libc-header-start.h>, to discourage inclusion outside glibc as
requested. __USE_GNU conditions on affected functions are changed to
__GLIBC_USE (LIB_EXT2), while it's added as an additional alternative
on the conditions for functions already enabled for some POSIX
versions.
It would be possible to convert existing __USE_* conditionals to
__GLIBC_USE (with the relevant __GLIBC_USE_* being defined in
<features.h> where __USE_* are presently defined), and so make them
typo-proof (given -Wundef -Werror in glibc builds) because __GLIBC_USE
is used with #if not #ifdef / #if defined.
No attempt is made to enforce the rule about diagnosing different
definitions of __STDC_WANT_LIB_EXT2__ when affected headers are
included; such a diagnostic is incompatible with multiple-include
guards on the affected headers, unless compiler extensions are added
to support it.
As previously noted, glibc does not implement all features from TR
24731-2:2010: the functions aswprintf vaswprintf getwdelim getwline
are not in glibc, although they would be appropriate to add if someone
wished to do so. But I think it makes sense to support the feature
test macro if *any* of the controlled features are present in glibc.
Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch).
* bits/libc-header-start.h: New file.
* Makefile (headers): Add bits/libc-header-start.h.
* include/features.h (__STDC_WANT_LIB_EXT2__): Document.
(__GLIBC_USE): New macro.
* libio/stdio.h: Define
__GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION and include
<bits/libc-header-start.h> instead of including <features.h>.
(fmemopen): Declare also if [__GLIBC_USE (LIB_EXT2)].
(open_memstream): Likewise.
(vasprintf): Declare if [__GLIBC_USE (LIB_EXT2)], not [__USE_GNU].
(__asprintf): Likewise.
(asprintf): Likewise.
(__getdelim): Declare also if [__GLIBC_USE (LIB_EXT2)].
(getdelim): Likewise.
(getline): Likewise.
* string/string.h: Define
__GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION and include
<bits/libc-header-start.h> instead of including <features.h>.
(strdup): Declare also if [__GLIBC_USE (LIB_EXT2)]
(strndup): Likewise.
* wcsmbs/wchar.h: Define
__GLIBC_INTERNAL_STARTING_HEADER_IMPLEMENTATION and include
<bits/libc-header-start.h> instead of including <features.h>.
(open_wmemstream): Declare also if [__GLIBC_USE (LIB_EXT2)].
* manual/creature.texi (__STDC_WANT_LIB_EXT2__): Document macro.
features.h is not clean with -Wundef (for the installed header, of
course this only appears with -Wsystem-headers). In ISO C standards
modes, you get a series of warnings / errors relating to
_POSIX_C_SOURCE and _XOPEN_SOURCE not being defined when tested in
standards mode and uses #undef _GNU_SOURCE to avoid the default
_GNU_SOURCE from libc-symbols.h. This patch changes the relevant #if
conditionals to avoid these warnings / errors.
Tested for x86_64 and x86 (testsuite, and that installed shared
libraries are unchanged by the patch).
[BZ #19212]
* include/features.h [(_XOPEN_SOURCE - 0) >= 500]: Change
conditional to [defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >=
500].
[_POSIX_C_SOURCE >= 1]: Change conditional to [defined
_POSIX_C_SOURCE && _POSIX_C_SOURCE >= 1].
[(_POSIX_C_SOURCE - 0) >= 199309L]: Change conditional to [defined
_POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199309L].
[(_POSIX_C_SOURCE - 0) >= 199506L]: Change conditional to [defined
_POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199506L].
[(_POSIX_C_SOURCE - 0) >= 200112L]: Change conditional to [defined
_POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200112L].
[(_POSIX_C_SOURCE - 0) >= 200809L]: Change conditional to [defined
_POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200809L].
Source packages that need to support both 2.19 and
2.20 will need to decide to use _BSD_SOURCE and
_SVID_SOURCE vs. _DEFAULT_SOURCE.
The difficulty in making that decision is that
__GLIBC_MINOR__ is itself defined in features.h,
but you want to set the feature test macros before
including features.h.
Therefore to ease the transition we should disable
the warning if _DEFAULT_SOURCE is also defined.
https://sourceware.org/ml/libc-alpha/2014-02/msg00666.htmlhttps://sourceware.org/glibc/wiki/Release/2.20#Packaging_Changes
This is a minimal patch to remove _BSD_SOURCE and _SVID_SOURCE from
the documented user API, making them into aliases for _DEFAULT_SOURCE
with a #warning given, but keeping most of the features.h logic using
those macros and all the exising __USE_* conditionals, on the basis
that all the consequent cleanups will go in followup patches.
Tested x86_64.
* include/features.h: Update comment documenting feature test
macros.
[_BSD_SOURCE || _SVID_SOURCE]: Give #warning. Define
_DEFAULT_SOURCE.
* manual/creature.texi (_BSD_SOURCE): Remove documentation.
(_SVID_SOURCE): Likewise.
(_DEFAULT_SOURCE): Update description of default features.
(Feature Test Macros): Don't mention _SVID_SOURCE in conjunction
with _GNU_SOURCE.
* manual/filesys.texi (__ftw_func_t): Do not refer to _BSD_SOURCE.
(S_ISVTX): Likewise.
* manual/math.texi (Mathematical Constants): Likewise.
* manual/signal.texi (Interrupted Primitives): Likewise.
* manual/startup.texi (putenv): Do not refer to _SVID_SOURCE.
* math/test-matherr.c (_SVID_SOURCE): Do not define.
* sysvipc/sys/ipc.h [__USE_SVID && !__USE_XOPEN && __GNUC__ >= 2]:
Don't refer to _SVID_SOURCE in warning text.
This patch adds a feature test macro _DEFAULT_SOURCE to enable the
default set of header declarations.
The intention is: if _DEFAULT_SOURCE is not used there is no change to
the set of __USE_* macros glibc defines; if it's used on its own, and
without compiler options such as -std=c99 that define __STRICT_ANSI__,
again, there is no change; if it's used together with the macros it
approximately (i.e., apart from __USE_POSIX_IMPLICITLY) implies
(-D_BSD_SOURCE -D_SVID_SOURCE -D_POSIX_C_SOURCE=200809L), again, there
is no change. Otherwise, it causes the relevant features to be
enabled, even if __STRICT_ANSI__, or another feature test macro, would
cause them to be disabled.
This macro deliberately bundles the POSIX.1-2008 (non-X/Open)
functionality with the BSD/SVID/"misc" functionality, rather than
defining a macro that gives just the latter, as many of the header
cleanups resulting from removing _BSD_SOURCE and _SVID_SOURCE support
are only possible when BSD/SVID/"misc" is always bundled with
POSIX.1-2008.
Tested x86_64.
* include/features.h: Update comment documenting feature test
macros. Mention _DEFAULT_SOURCE in comment.
[_GNU_SOURCE] (_DEFAULT_SOURCE): Undefine and redefine.
[_DEFAULT_SOURCE]: Undefine and redefine _DEFAULT_SOURCE,
_BSD_SOURCE and _SVID_SOURCE.
[!__STRICT_ANSI__ && !_ISOC99_SOURCE && !_POSIX_SOURCE &&
!_POSIX_C_SOURCE && !_XOPEN_SOURCE && !_BSD_SOURCE &&
!_SVID_SOURCE]: Likewise.
[_DEFAULT_SOURCE && !_POSIX_SOURCE && !_POSIX_C_SOURCE]
(__USE_POSIX_IMPLICITLY): Define.
[_DEFAULT_SOURCE && !_POSIX_SOURCE && !_POSIX_C_SOURCE]
(_POSIX_SOURCE): Undefine and redefine.
[_DEFAULT_SOURCE && !_POSIX_SOURCE && !_POSIX_C_SOURCE]
(_POSIX_C_SOURCE): Likewise.
* manual/creature.texi (_DEFAULT_SOURCE): Document.
(Feature Test Macros): Update documentation of default features.
