[Bug fortran/47491] [4.6 Regression] libgfortran: getpwuid_r (for GETLOG) breaks bootstrapping

["jb at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47491

Janne Blomqvist <jb at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                URL|                            |http://gcc.gnu.org/ml/gcc-p
                   |                            |atches/2011-01/msg02026.htm
                   |                            |l

--- Comment #4 from Janne Blomqvist <jb at gcc dot gnu.org> 2011-01-27 17:10:42 UTC ---
Patch: http://gcc.gnu.org/ml/gcc-patches/2011-01/msg02026.html

(In reply to comment #3)
> > --- Comment #2 from Janne Blomqvist <jb at gcc dot gnu.org> 2011-01-27 16:10:41 UTC ---
> > Some git-grepping showed that at least libjava has in configure.ac
> >
> > AC_DEFINE(_POSIX_PTHREAD_SEMANTICS, 1, [Required define if using POSIX
> > threads])
> >
> > and in case Boehm GC is not used (which libgfortran never uses):
> >
> > AC_DEFINE(_REENTRANT, 1, [Required define if using POSIX threads])
> >
> > However, if I understand gcc/config/ correctly, _REENTRANT should be
> > automatically set for all targets that need it.
> 
> At least on Solaris (and I think on other targets as well), only with
> -pthread.

I think that's Ok. If we're not building with threads, and lack of _REENTRANT
causes the _r() functions not to be seen, gfortran falls back to the non-_r()
functions, which is no problem on a non-threaded build.

> > Also in gcc/config a few targets set 
> >
> > -D_POSIX_C_SOURCE=199506L
> >
> > (not Solaris, though). But apparently we shouldn't go and set this somewhere in
> > libgfortran? That is, at least no other library does this..
> 
> That may not provide the best guidance.  I'd rather look for autoconf
> and/or gnulib here.  On Solaris, this may not be enough: starting with
> Solaris 10, there's POSIX.1-2001 support via -D_POSIX_C_SOURCE=200112L.

The comments at

http://blogs.gnome.org/tthurman/2008/11/23/_posix_c_source/

suggests defining POSIX_C_SOURCE might not be such a good idea, so I think it's
best to avoid this.

Also, for GNU platforms

http://www.gnu.org/s/libc/manual/html_node/Feature-Test-Macros.html

seems _GNU_SOURCE is sort of a superset of POSIX_C_SOURCE and the kitchen sink.
Which is what we're using today, hopefully the AC_USE_SYSTEM_EXTENSIONS thing
is enough to make things work on other targets.