> -mabi=name Generate code for the specified calling convention. [...] The default is to use the Microsoft ABI when targeting Microsoft Windows and the SysV ABI on all other systems.
> -mms-bitfields Enable/disable bit-field layout compatible with the native Microsoft Windows compiler. [...] This option is enabled by default for Microsoft Windows targets.
(Not OP) The C++ ABI on Windows isn't compatible between g++ and MSVC, even though the C ABI is. Libraries using C linkage should work fine. MinGW-built programs link against the Microsoft C runtime (MSVCRT.DLL by default) which is itself MSVC-built, so linking MinGW programs to MSVC libraries has to work for anything to work.
