I generated MSYS Makefiles for Avro C++ by executing the following command in the avro/lang/c++ directory:
cmake -G "MSYS Makefiles"
However, when trying to "make" Avro C++ with the generated makefiles and with MinGW GCC, the build fails with the following error:
g++.exe: C:/msys/EHa: No such file or directory
make: *** [CMakeFiles/avrocpp_s.dir/impl/Compiler.cc.obj] Error 1
make: *** [CMakeFiles/avrocpp_s.dir/all] Error 2
make: *** [all] Error 2
It turns out that the Visual Studio compiler flag "/Eha" was added to the generated makefiles, which MSYS then interpreted as a file path. MinGW GCC would not understand or need that flag anyway.