I think the problem here is that it only builds with MSVS and only when MFC is available (which is not always the case any more). So we'd need to test that MSVS is being used (probably simple) and ideally also that MFC is available (e.g. by checking for one of its headers?), otherwise this will break the build for all MinGW users.

it is possible with MSVC CMake Variable to check compiler is Visual Studio. MFC base header file is afxwin.h

Checking MSVC is probably the right thing to do, I'll look at a fix.

Testing for MSVC is simple, but testing that MFC is available is not, so somebody would need to do it. For now I'm closing it as it can't be applied as is.

Using FindMFC and adding the MFC sample only when MFC_FOUND would seem an obvious solution but I cannot test it and using it could add unwanted dependencies to projects (but I don't see anything like that there).