https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67116
--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> --- The thread model is determined using: target_thread_file=`$CXX -v 2>&1 | sed -n 's/^Thread model: //p'` where $CXX is *supposed* to be the newly-built GCC, e.g. for my native builds the value of CXX is /home/jwakely/src/gcc/build/./gcc/xgcc -shared-libgcc -B/home/jwakely/src/gcc/build/./gcc -nostdinc++ -L/home/jwakely/src/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/src -L/home/jwakely/src/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs -L/home/jwakely/src/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/libsupc++/.libs -B/home/jwakely/gcc/6/x86_64-pc-linux-gnu/bin/ -B/home/jwakely/gcc/6/x86_64-pc-linux-gnu/lib/ -isystem /home/jwakely/gcc/6/x86_64-pc-linux-gnu/include -isystem /home/jwakely/gcc/6/x86_64-pc-linux-gnu/sys-include For a mingw64 cross I see /tmp/67116/./gcc/xgcc being used, so I don't know why your config.log shows x86_64-w64-mingw32-c++ being used. Are you setting CXX or doing anything funny in the libstdc++ build dir?
