The way I saw it was that if I had different output files (say, "library.lib" and "library.a") and/or different additional options (say, "/nologo" and "-O") in the build targets (I also use MSVC and MinGW), then I could not build, because the "/nologo" switch was passed to MinGW, which complained; at another run MinGW was trying to build "library.lib" instead of "library.a".
This seems to be a real problem to me, as I need MSVC library in the end, but there is no debugger for MSVC (or did I miss one?).
Mike