scummvm/scummvm — comment on commit 77c9be7998b85da24ae292f7eda1e478b32f2e64
File:  line 0
By dhewg:

The reason why I excluded these 2 symbols for mingw was that some of the compile errors origin from backends/graphics/opengl/gltexture.h. That includes windows.h. On mingw, windows.h includes intrin.h (on some deeper level). Excludes in a public header looked hackish to me, just like excluding them on every spot that directly or indirectly includes intrin.h.
Now, wjp pointed out that MSVC is also affected, there's a hack for intrin.h in common/math.h for that.
The current idea is to remove the mingw-w64 specific defines from forbidden.h again and add the excludes to scummsys.h, but for everything _WIN32.