Bug#575997: libstdc++6-4.5-dev: c++config.h doesn't seem to match reality

[Matthias Klose <doko@debian.org>]

On 31.03.2010 07:34, Miles Bader wrote:
> The file "/usr/include/c++/4.5/x86_64-linux-gnu/bits/c++config.h"
> doesn't seem to actually reflect the available facilities of the system.
[...]
> Is there a good reason these features are disabled when they are
> apparently available?
>
> If not, could they please be enabled?

Same in 4.4.

libstdc++-v3/acinclude.m4:
dnl Check for clock_gettime, nanosleep and sched_yield, used in the
dnl implementation of 20.8.5 [time.clock], and 30.2.2 [thread.thread.this]
dnl in the current C++0x working draft.
dnl
dnl --enable-libstdcxx-time
dnl --enable-libstdcxx-time=yes
dnl        checks for the availability of monotonic and realtime clocks,
dnl        nanosleep and sched_yield in libc and libposix4 and, in case, links
dnl       the latter
dnl --enable-libstdcxx-time=rt
dnl        also searches (and, in case, links) librt.  Note that this is
dnl        not always desirable because, in glibc, for example, in turn it
dnl        triggers the linking of libpthread too, which activates locking,
dnl        a large overhead for single-thread programs.
dnl --enable-libstdcxx-time=no
dnl --disable-libstdcxx-time
dnl        disables the checks completely

not enabled by other distributions as well. asked upstream:
http://gcc.gnu.org/ml/libstdc++/2010-04/msg00007.html

  Matthias