https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94770
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #9) > At least, when using: > gcc version 9.2.1 20190827 (Fedora MinGW 9.2.1-1.fc31) (GCC) > and executing with Wine. Yeah, I can clearly see it in the assembly that it must ICE, the big question is what is the right ABI, if the empty structures are not passed at all (like e.g. in the x86-64 clarified psABI), or if they are passed as clearly is what happens in the caller. On the va_arg side, for the MS ABI va_list seems to be a pointer and thus it defers to the standard middle-end handling where it see a TYPE_EMPTY_P? struct and uses 0 size instead of the actual one. Now, not sure if we can tweak the *RECORD_EMPTY_P* target hook, because it marks types rather than their uses, and in sources where both x86-64 psABI and msabi are used together, we want TYPE_EMPTY_P being set for the former and perhaps not? for the latter. Of course, the backend coiuld check for the MSABI and TYPE_EMPTY_P type and don't defer to the middle-end in that case and handle it differently. BTW, when I tried clang++ (10.0.0 trunk 374035 version) with -target x86_64-w64-mingw32, it seems it matches g++ on the caller side and does something on the callee side, but I bet MSVC is the ABI etalon on this target, right?
