std::mutex is indeed a C++11 feature. But I think "-std=gnu++14" is GCC's default for C++ code by now:
https://gcc.gnu.org/onlinedocs/gcc/C...ialect-Options
Anyhow, whether setting CXXFLAGS or CFLAGS has any effect, that totally depends on the build system (e.g. Makefile) that is used to build the application!
For example, you may need to specify those when running the
./configure script, so that they will actually be applied to the generated Makefile.
Also, make sure that your MinGW was built with "posix" threading (libwinpthread). If built with "win32" threading, C++11 threading features are
not available!
More info on that topic here:
*
https://stackoverflow.com/a/30390278
*
https://wiki.qt.io/MinGW-64-bit#GCC_...ix_vs_win32.29