Re: Error building gcc-5.* with threads=win32

[niXman <i.nixman@autistici.org>]

niXman 2015-08-01 11:32:
> Hi,
> 
> I have successfully built gcc-4.8.*/4.9.* as MinGW-w64 with
> --enable-threads=win32 but I can't build gcc-5.* with the same
> options.
> Error occurs when building libatomic on stage 3.
> 
> If I change the '--enable-threads=win32' option on
> '--enable-threads=posix' then it builds successfully.
> 
> 
> configure: error: in
> `/c/mingw520/i686-520-win32-sjlj-rt_v4-rev0/build/gcc-5.2.0/i686-w64-mingw32/64/libatomic':
> configure: error: C compiler cannot create executables
> See `config.log' for more details.
> 
> 
> libatomic/config.log:
> configure:3566: checking for C compiler default output file name
> configure:3588:
> /c/mingw520/i686-520-win32-sjlj-rt_v4-rev0/build/gcc-5.2.0/./gcc/xgcc
> -B/c/mingw520/i686-520-win32-sjlj-rt_v4-rev0/build/gcc-5.2.0/./gcc/
> -L/mingw32/i686-w64-mingw32/lib -L/mingw32/mingw/lib -isystem
> /mingw32/i686-w64-mingw32/include -isystem /mingw32/mingw/include
> -B/mingw32/i686-w64-mingw32/bin/ -B/mingw32/i686-w64-mingw32/lib/
> -isystem /mingw32/i686-w64-mingw32/include -isystem
> /mingw32/i686-w64-mingw32/sys-include  -m64 -g -O2 -pipe
> -I/c/mingw520/i686-520-win32-sjlj-rt_v4-rev0/mingw32/opt/include
> -I/c/mingw520/prerequisites/i686-zlib-static/include
> -I/c/mingw520/prerequisites/i686-w64-mingw32-static/include
> -fno-sync-libcalls  -march=i486 -mtune=i686 -fomit-frame-pointer
> conftest.c  >&5
> conftest.c:1:0: error: CPU you selected does not support x86-64 
> instruction set
> 
> As you can see here are simultaneously used the '-m64 -march=i486
> -mtune=i686' options.
> 
> 
> Question is, why and how can I fix it?

This bug is also present in the gcc-trunk.