[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 Jonathan Wakely redi at gcc dot gnu.org changed: What|Removed |Added Status|NEW |RESOLVED Resolution||FIXED --- Comment #48 from Jonathan Wakely redi at gcc dot gnu.org 2012-11-06 11:35:22 UTC --- Fixed for 4.8
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 Jonathan Wakely redi at gcc dot gnu.org changed: What|Removed |Added Target Milestone|--- |4.8.0 --- Comment #47 from Jonathan Wakely redi at gcc dot gnu.org 2012-10-10 23:19:56 UTC --- should be fixed on trunk, by http://gcc.gnu.org/ml/gcc-cvs/2012-10/msg00457.html
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 Jonathan Wakely redi at gcc dot gnu.org changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2012-10-08 Summary|--enable-libstdcxx-time=yes |--enable-libstdcxx-time=yes |doesn't find the functional |doesn't find the function |nanosleep() on darwin |nanosleep() on darwin Ever Confirmed|0 |1 --- Comment #37 from Jonathan Wakely redi at gcc dot gnu.org 2012-10-08 16:47:46 UTC --- (In reply to comment #36) (In reply to comment #33) So is _GLIBCXX_USE_SCHED_YIELD defined on darwin? Yes, passing --enable-libstdcxx-time=yes and allowing nanosleep() to be found on darwin also results in... ./c++/4.8.0/x86_64-apple-darwin12.2.0/bits/c++config.h:#define _GLIBCXX_USE_SCHED_YIELD 1 ./c++/4.8.0/x86_64-apple-darwin12.2.0/i386/bits/c++config.h:#define _GLIBCXX_USE_SCHED_YIELD 1 The check for sched_yield has nothing to do with nanosleep, that must have always ben defined.
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #38 from Jack Howarth howarth at nitro dot med.uc.edu 2012-10-08 17:03:39 UTC --- I assume the option of using... Index: libstdc++-v3/config/os/bsd/darwin/os_defines.h === --- libstdc++-v3/config/os/bsd/darwin/os_defines.h(revision 192213) +++ libstdc++-v3/config/os/bsd/darwin/os_defines.h(working copy) @@ -42,4 +42,8 @@ // Static initializer macro is buggy in darwin, see libstdc++/51906 #define _GTHREAD_USE_RECURSIVE_MUTEX_INIT_FUNC +// Use nanosleep and sched_yield in libc for C++11 standard. +#define _GLIBCXX_USE_NANOSLEEP 1 +#define _GLIBCXX_USE_SCHED_YIELD 1 + #endif ...eliminates our ability to toggle this support off with --disable-libstdcxx-time, right? This is my only concern with this approach versus the patch in comment 32;
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #39 from Jonathan Wakely redi at gcc dot gnu.org 2012-10-08 17:16:13 UTC --- Yes, but why do you want to disable it? Why does that patch define _GLIBCXX_USE_SCHED_YIELD? That is correctly detected anyway by configure, without any changes, as I said in comment 30 and again in comment 37
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #40 from Jeremy Huddleston Sequoia jeremyhu at macports dot org 2012-10-08 18:33:37 UTC --- (In reply to comment #25) N.B. prior to POSIX 2008 nanosleep was part of the Timers option, if OS X supports that it should define _POSIX_TIMERS to 0, -1 or 200112L to indicate it's supported. POSIX 2008 moves the Timers functionality to the Base spec, and requires that _POSIX_TIMERS is defined to 200809L. In eiher case, a POSIX system supporting nanosleep should define _POSIX_TIMERS. It is defined to -1 because OS X does not support all that _POSIX_TIMERS entails. I still don't see why the _POSIX_TIMERS 0 check exists at all. On systems that don't have it, the tests will simply fail because timespec or nanosleep are undefined. The configure checks are based on well-documented, publicly-available standards, please try to understand them instead of proposing patches based on the misunderstanding that adding struct makes any difference to anything. I very much understand the standards, and I've provided a link to them. The standard itself does not require _POSIX_TIMERS to be defined for nanosleep to be supported, and it specifically states 'struct timespec' in the function prototype. (In reply to comment #26) If Apple or anyone else wants it to work otherwise they need to do the work, as GCC maintainers have no reason to do support building parts of GCC without GCC! Apple is fully committed to libc++. If anyone wants libstdc++ to work on Darwin, it is clear that it will need to be a community effort. (In reply to comment #29) _POSIX_TIMERS=200112L would mean darwin provides a pre-2008 nanosleep, -1 means the Timers option is not supported. Yes, it is not *fully* supported. Or are you going to demand that the use of pre-2008 POSIX nanosleep() be only accepted on a target-specific basis? There are plenty of systems with a 2001 nanosleep that define _POSIX_TIMERS to 20112L, but darwin seems to support nanosleep without the rest of the Timers option. I don't want to remove the correct check for _POSIX_TIMERS just for one system's peculiarities. It's not one system. You are misreading the spec. _POSIX_TIMERS 0 implies that all the functionality is available. That is the only thing you can deduce from that check. It is perfectly valid to have a conforming nanosleep with _POSIX_TIMERS = -1. Why are you even othering to put that code inside of a _POSIX_TIMERS 0 check. If _POSIX_TIMERS 0, you're guaranteed (by the standard) to have that functionality, so there's no point in checking... if you want to support all platforms, it's better to just check for nanosleep directly without the _POSIX_TIMERS check. (In reply to comment #39) Yes, but why do you want to disable it? Why does that patch define _GLIBCXX_USE_SCHED_YIELD? I think his patch has no effect on _GLIBCXX_USE_SCHED_YIELD ... I think he wasn't seeing _GLIBCXX_USE_SCHED_YIELD before because of a mistype he was having with the configure option. With Rob's patch, I see both _GLIBCXX_USE_SCHED_YIELD and _GLIBCXX_USE_NANOSLEEP defined to 1. That is correctly detected anyway by configure, without any changes, as I said in comment 30 and again in comment 37 Yes, it is.
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #41 from Jonathan Wakely redi at gcc dot gnu.org 2012-10-08 19:50:21 UTC --- (In reply to comment #40) I still don't see why the _POSIX_TIMERS 0 check exists at all. On systems that don't have it, the tests will simply fail because timespec or nanosleep are undefined. The existence of a function called nanosleep doesn't mean it's the right one, or that it will be found at link time, or available at run-time. Checking _POSIX_TIMERS 0 means the functionality is actually usable, without checking sysconf() at run-time as described by POSIX.1b-2001. The configure checks are based on well-documented, publicly-available standards, please try to understand them instead of proposing patches based on the misunderstanding that adding struct makes any difference to anything. I very much understand the standards, and I've provided a link to them. (That was a link to clock_nanosleep not nanosleep, which was a different option, not Timers ;) That comment wasn't aimed at you... The standard itself does not require _POSIX_TIMERS to be defined for nanosleep to be supported, and it specifically states 'struct timespec' in the function prototype. ... but you do still seem to doubt that the struct is unnecessary in C++. Maybe you've noticed how you don't need to say: class std::string str = a string; ^ to use C++ classes. It's the same for structs. (In reply to comment #26) If Apple or anyone else wants it to work otherwise they need to do the work, as GCC maintainers have no reason to do support building parts of GCC without GCC! Apple is fully committed to libc++. If anyone wants libstdc++ to work on Darwin, it is clear that it will need to be a community effort. Again, there's a difference between *working* (i.e. being usable) on darwin and being able to build libstdc++ with a different compiler. There is no requirement to be able to configure libstdc++ with anything other than G++, but in any case I assure you that clang++ doesn't require the 'struct' keyword either. It's not one system. You are misreading the spec. No I'm not, my words you quoted carefully made the distinction of saying -1 means the Timers option is not supported, not that nanosleep is not supported: _POSIX_TIMERS=200112L would mean darwin provides a pre-2008 nanosleep, -1 means the Timers option is not supported. (I was admittedly less careful in comment 25, sorry) I'd be happy to improve the test to support other systems, but the patches posted to this PR so far have been unacceptable due to failing to understand the existing checks, failing to meet libstdc++'s configury conventions, or adding support for a single system rather than for any systems which provide nanosleep without the rest of the Timers option. In the absence of a decent patch I suggest defining the HAVE_NANOSLEEP macro in os_defines.h and moving on. Why are you even othering to put that code inside of a _POSIX_TIMERS 0 check. If _POSIX_TIMERS 0, you're guaranteed (by the standard) to have that functionality, so there's no point in checking... The existence of a preprocessor symbol doesn't tell you whether you need to link to a particular library to use the function. The check is AC_TRY_LINK which will ensure not only is the function declared but the symbol is found, having added -lposix4 or -lrt to the link line if earlier checks indicate they're needed. if you want to support all platforms, it's better to just check for nanosleep directly without the _POSIX_TIMERS check. If _POSIX_TIMERS is defined to 0 the code might compile but not work at run-time. I didn't write those checks, but I'm not inclined to remove the tests of the POSIX option macros just to fix this PR. That is correctly detected anyway by configure, without any changes, as I said in comment 30 and again in comment 37 Yes, it is. Gread, thanks for confirming that.
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #42 from Jeremy Huddleston Sequoia jeremyhu at macports dot org 2012-10-08 20:10:26 UTC --- (In reply to comment #41) (In reply to comment #40) I still don't see why the _POSIX_TIMERS 0 check exists at all. On systems that don't have it, the tests will simply fail because timespec or nanosleep are undefined. The existence of a function called nanosleep doesn't mean it's the right one, or that it will be found at link time, or available at run-time. Checking _POSIX_TIMERS 0 means the functionality is actually usable, without checking sysconf() at run-time as described by POSIX.1b-2001. Right, but as we see here, the converse is not true. ie: This is true: (_POSIX_TIMERS 0) = (nanosleep is the one you want) This is not true: (nanosleep is the one you want) = (_POSIX_TIMERS 0) You want to find an test such that: (your test) = (nanosleep is the one you want) (That was a link to clock_nanosleep not nanosleep, which was a different option, not Timers ;) Aww sorry. I copy-linked the wrong one, but meh. ... but you do still seem to doubt that the struct is unnecessary in C++. No. I don't doubt that. I admitted in comment #20 that C++ is not a strength of mine, so thanks for letting me know about this detail. Maybe you've noticed how you don't need to say: class std::string str = a string; ^ to use C++ classes. It's the same for structs. Yeah, I knew about class, but I didn't know about that for structs. I thought it wasn't possible to drop 'struct' in C++ as it's not possible to drop it in C (although most users will typedef). Thanks for teaching me something new. Again, there's a difference between *working* (i.e. being usable) on darwin and being able to build libstdc++ with a different compiler. There is no requirement to be able to configure libstdc++ with anything other than G++, but in any case I assure you that clang++ doesn't require the 'struct' keyword either. I don't doubt it. I was just trying to make the usage strictly match the POSIX spec. It's not one system. You are misreading the spec. No I'm not, my words you quoted carefully made the distinction of saying -1 means the Timers option is not supported, not that nanosleep is not supported: Ok. I'd be happy to improve the test to support other systems, but the patches posted to this PR so far have been unacceptable due to failing to understand the existing checks, failing to meet libstdc++'s configury conventions, or adding support for a single system rather than for any systems which provide nanosleep without the rest of the Timers option. In the absence of a decent patch I suggest defining the HAVE_NANOSLEEP macro in os_defines.h and moving on. Why are you even othering to put that code inside of a _POSIX_TIMERS 0 check. If _POSIX_TIMERS 0, you're guaranteed (by the standard) to have that functionality, so there's no point in checking... The existence of a preprocessor symbol doesn't tell you whether you need to link to a particular library to use the function. Ah, I forgot you were checking for library linkage as well. That makes sense. The check is AC_TRY_LINK which will ensure not only is the function declared but the symbol is found, having added -lposix4 or -lrt to the link line if earlier checks indicate they're needed. That makes sense. if you want to support all platforms, it's better to just check for nanosleep directly without the _POSIX_TIMERS check. If _POSIX_TIMERS is defined to 0 the code might compile but not work at run-time. I didn't write those checks, but I'm not inclined to remove the tests of the POSIX option macros just to fix this PR. Ok, what about just using _POSIX_TIMERS 0 || defined(__APPLE__)? That may miss some other OSs in the same boat, but they can always add similar checks.
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #43 from Jack Howarth howarth at nitro dot med.uc.edu 2012-10-08 20:31:01 UTC --- Both OpenBSD and FreeBSD seem to have nanosleep calls documented as... The nanosleep() function conforms to IEEE Std 1003.1b-1993 (``POSIX'') like Apple's. On the other hand, using a patch like... Index: libstdc++-v3/config/os/bsd/darwin/os_defines.h === --- libstdc++-v3/config/os/bsd/darwin/os_defines.h(revision 19) +++ libstdc++-v3/config/os/bsd/darwin/os_defines.h(working copy) @@ -42,4 +42,9 @@ // Static initializer macro is buggy in darwin, see libstdc++/51906 #define _GTHREAD_USE_RECURSIVE_MUTEX_INIT_FUNC +// Use nanosleep and sched_yield in libc for time.clock and +// thread.thread.this in C++11 standard. +#define _GLIBCXX_USE_NANOSLEEP 1 +#define _GLIBCXX_USE_SCHED_YIELD 1 + #endif will effectively default darwin to --enable-libstdcxx-time=yes and eliminates a configure option.
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #44 from Jonathan Wakely redi at gcc dot gnu.org 2012-10-08 20:42:22 UTC --- (In reply to comment #42) You want to find an test such that: (your test) = (nanosleep is the one you want) That's why I was asking about other feature test macros that would allow us to detect systems supporting the POSIX.1b-1993 Realtime Extensions, but not the later Timers option, or the POSIX-2008 Base. Ok, what about just using _POSIX_TIMERS 0 || defined(__APPLE__)? That may miss some other OSs in the same boat, but they can always add similar checks. Because we generally try to avoid littering acinclude.m4 with such checks. The other OSs can add defines to their own os_defines.h files if needed. (In reply to comment #43) will effectively default darwin to --enable-libstdcxx-time=yes and eliminates a configure option. That's a *good* thing. If the platform unconditionally supports the feature and doesn't need a configure check why would you want to prevent using it? All that achieves is an incomplete libstdc++ with missing functionality.
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #45 from Jack Howarth howarth at nitro dot med.uc.edu 2012-10-08 22:27:08 UTC --- I can confirm the existence of sched_yield() back to Libc-166 in 1997 on darwin. http://opensource.apple.com/source/Libc/Libc-166/pthreads.subproj/sched.h The nanosleep() call appears at least by Libc-262.2.12 in 2003 on darwin... http://opensource.apple.com/source/Libc/Libc-262.2.12/include/time.h and probably goes back further but the archived Libc don't show the time.h header before then.
[Bug libstdc++/54847] --enable-libstdcxx-time=yes doesn't find the function nanosleep() on darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54847 --- Comment #46 from Jack Howarth howarth at nitro dot med.uc.edu 2012-10-09 00:46:08 UTC --- Revised patch posted to libstdc++ mailing list... http://gcc.gnu.org/ml/libstdc++/2012-10/msg00047.html
