Public bug reported:
INTRODUCTION
--------------------------
The C++ library has internal macros called _GLIBCXX_USE_NANOSLEEP and
_GLIBCXX_USE_SCHED_YIELD.
Normally the macros are defined in x86_64-linux-gnu/32/bits/c++config.h
and x86_64-linux-gnu/bits/c++config.h.
When _GLIBCXX_USE_NANOSLEEP is defined, the standard library has support
for crucial components related to time.
Specifically, in "thread" there is a section which begins with "#ifdef
_GLIBCXX_USE_NANOSLEEP" and declares "sleep_until", "sleep_for",
"nanosleep", "chrono::seconds", "chrono::nanoseconds", etc. There
functions / types are an important part of C++ standard.
The _GLIBCXX_USE_SCHED_YIELD macro enables "yield()" method.
PROBLEM
--------------------------
C++ code which depends on the relevant parts of the C++ standard simply cannot
be compiled.
There is no known and reliable workaround for this problem.
WHY IT HAPPENED
--------------------------
I am not 100% sure, but there seem to be a bug in a test program which check
for the presence of nanosleep. It is a part of "configure", which is in turn
generated from acinclude.m4.
In order to test for nanosleep the following program is used:
#include <unistd.h>
#include <time.h>
int
main ()
{
#if _POSIX_TIMERS > 0 && defined(_POSIX_MONOTONIC_CLOCK)
timespec tp;
#endif
clock_gettime(CLOCK_MONOTONIC, &tp);
;
return 0;
}
The program is missing "struct" before "timespec tp;". In fact, there
are three places in the file where the "struct" is missing.
As for "yield", I am not sure yet why it is missing but the reason is
probably similar.
SCOPE
--------------------------
Both macros are NOT enabled in Ubuntu releases after 12.04 LTS, including the
to-be-released Ubuntu 14.04 LTS.
For example, on Ubuntu 13.10:
rtvd@localhost $ pwd
/usr/include/c++
rtvd@localhost $ grep -r _GLIBCXX_USE_NANOSLEEP *
4.6/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.6/x86_64-linux-gnu/32/bits/c++config.h:/* #undef _GLIBCXX_USE_NANOSLEEP */
4.6/x86_64-linux-gnu/bits/c++config.h:/* #undef _GLIBCXX_USE_NANOSLEEP */
4.6.4/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.6.4/x86_64-linux-gnu/32/bits/c++config.h:/* #undef _GLIBCXX_USE_NANOSLEEP */
4.6.4/x86_64-linux-gnu/bits/c++config.h:/* #undef _GLIBCXX_USE_NANOSLEEP */
4.7/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.7.3/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.8/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.8.1/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
On Ubuntu 12.04 LTS (notice #define ...) everything is good:
rtvd@localhost $ pwd
/usr/include/c++
rtvd@localhost $ grep -r _GLIBCXX_USE_NANOSLEEP *
4.6/x86_64-linux-gnu/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.6/x86_64-linux-gnu/32/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.6/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.6.3/x86_64-linux-gnu/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.6.3/x86_64-linux-gnu/32/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.6.3/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
On Debian 7.3 the macros are defined (notice #define ... in each version
of the library), so C++ library is good there too:
rtvd@debiantest:/usr/include/c++$ pwd
/usr/include/c++
rtvd@debiantest:/usr/include/c++$ grep -r _GLIBCXX_USE_NANOSLEEP *
4.6/x86_64-linux-gnu/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.6/x86_64-linux-gnu/32/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.6/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.6.3/x86_64-linux-gnu/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.6.3/x86_64-linux-gnu/32/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.6.3/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.7/x86_64-linux-gnu/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.7/x86_64-linux-gnu/32/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.7/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
4.7.2/x86_64-linux-gnu/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.7.2/x86_64-linux-gnu/32/bits/c++config.h:#define _GLIBCXX_USE_NANOSLEEP 1
4.7.2/thread:#ifdef _GLIBCXX_USE_NANOSLEEP
** Affects: gcc-4.6 (Ubuntu)
Importance: Undecided
Status: New
** Tags: c++ libstdc++ macro nanosleep yield
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https://bugs.launchpad.net/bugs/1269803
Title:
C++ standard library is compiled with nanosleep and yield switched OFF
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