For the MS libraries that is most likely wrong on win64. Should be winapi or stdcall. win64 does not know cdecl. It knows only one calling convention. winapi selects the correct one on ms compilers based on a macro, cdecl too, but not on gnu. Note third party code can still be using cdecl, though.
MS provided code is ONLY cdecl if the headers for those libraries expressly say so.