[1718627440]

From https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html

> -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.

Doesn't this work in practice, due to bugs?

[electroly]

(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.