If I understand correctly the following lines make not possible to work with UNICODE paths on windows (built with MinGW-64 compiler)
#if defined(_WIN32) && !defined(__MINGW32__) && defined(_MSC_VER) && (_MSC_VER > 1310)
int LibRaw::open_file(const wchar_t *fname, INT64 max_buf_size)
Can __MINGW32__ macro be narrowed to __MINGW64__?
But it looks like that mingw64 std library has wide char file i/o functions (_wfopen).