The libraries were built with MSVC++ version 18 (2013), 64 bits and Intel Fortran 2015. Build type: Release. Tested with both Intel Fortran 2015 and 2017. Directories: \bin - DLLs and drivers (created ...

I have made a test in MSYS2 with a fpm project depending on gtk-fortran and PLplot and had the same errors as you with the single quotes. It was better with double quotes, but finally the compilation ...