[Bug libfortran/47945] REAL(8) output conversion error on MinGW32

["sgk at troutmask dot apl.washington.edu" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47945

--- Comment #14 from Steve Kargl <sgk at troutmask dot apl.washington.edu> 2011-03-02 18:17:30 UTC ---
On Wed, Mar 02, 2011 at 06:02:22PM +0000, burnus at gcc dot gnu.org wrote:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47945
> 
> --- Comment #13 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-03-02 18:02:15 UTC ---
> (In reply to comment #12)
> > could it be that it was the intention to set __USE_MINGW_ANSI_STDIO in effect?
> 
> Yes - and that is what does happen for _POSIX=1 on MinGW64. But it does not
> happen for _POSIX=1 on the 32bit MinGW.
> 
> Jerry et al.: Do you think the following patch is OK?
> 
> --- a/libgfortran/libgfortran.h
> +++ b/libgfortran/libgfortran.h
> @@ -33,6 +33,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If
> not, see
>     any system header file is included.  */
>  #if defined __MINGW32__
>  #  define _POSIX 1
> +#  define _POSIX_SOURCE 1
>  #  define gfc_printf gnu_printf
>  #else
>  #  define gfc_printf __printf__
> 

I though a leading underscore in C denoted the namespace
of the C compiler, and a userspace program should not 
set such a macro.  Guess I'll pull out n1256.pdf later
to read up on the convention.  You may want to ask Joseph.  

It may also be prudent to add

#if define _POSIX_SOURCE
#undef _POSIX_SOURCE
#endif 

prior to (re)setting it to 1.