std::mutex missing when building Qt app with MXE gcc

Question

I'm attempting to get a Qt application to build from the command line under linux targetted for windows. I've used mxe to build a toolchain for targetting windows but my build fails whinging about various thread related bits. mxe built with winpthreads and I know the Qt project will build on windows itself from inside of creator, using the pre-packaged mingw compiler. I'm successfully building using my ARM Linux cross compiler, so I just want to get windows done the same. I'm trying to get a one line build on a build server or from Jenkins for all my targets.

I'm guessing I'm missing something that I need to pass to mxe when doing the cross toolchain build or alternatively missing something I need to pass to qmake for this build to succeed.

Answer 1

The issue is with the default MXE build of GCC using win32 threads as opposed to mingws pthreads implementation.

Edit src/gcc.mk and ensure that winpthreads is added to the $(PKG)_DEPS list and then change the configure line so that --enable-threads=win32 becomes --enable-threads=posix.

Then re-make winpthreads and gcc. Note that there is a circular dependency here, you need to build gcc with win32 threads (the default) first THEN remake with winpthreads.

Thanks to Andreia Gaita for this - http://blog.worldofcoding.com/2014/05/cross-compiling-c11-without-going-madder.html

Answer 2

POSIX configuration was added to MXE (Building pthreads inline with gcc and enable optional posix threads in libgcc).

For example, to build qt with that (x64, shared, posix threads):

make MXE_TARGETS='x86_64-w64-mingw32.shared.posix' qt