[Bug libstdc++/67116] incorrect detection of thread model when cross-compiling the tool chain

[redi at gcc dot gnu.org]

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?