http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51749
--- Comment #21 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #20) > (In reply to Jakub Jelinek from comment #19) > > Has anyone checked recently what exactly we still need -D_GNU_SOURCE for in > > the public headers (as opposed to just the libstdc++ code), as compared to > > say _ISOC99_SOURCE for glibc, at least for C++11? > > I haven't checked, it would be useful to do so. There is some stuff used by > the --enable-clocale=gnu code such as uselocale (which is now part of POSIX > but not C99) but it might be possible to only require that from .cc files > not in headers. In __gnu_cxx namespace: extern "C" __typeof(uselocale) __uselocale; and in std namespace: typedef __locale_t __c_locale; suggests that it really is looking for the uselocale function just to get the prototype and declares the function itself, and we need an alternative to __locale_t. We can't include xlocale.h, because that would make locale_t symbol visible, and can't typedef __locale_t, because that could clash with <locale.h> definition -D_GNU_SOURCE etc. Thus it would need to be something like: // Hackish forward declaration in global namespace. struct __locale_struct; and then just do: extern "C" __locale_struct *__uselocale (__locale_struct *); in __gnu_cxx namespace and typedef __locale_struct * __c_locale; in std namespace.
