This is already available via the MSVC compiler integrated into the Visual Studio 2017 Build Tools (which is preinstalled on the Windows VM). This compiler supports both C++ and C (should be C99-ish).
It’s being successfully used here: https://travis-ci.com/kryptoslogic/haxm/jobs/159645300/config. See:
"language": "c"
Also related: C++ Support on Windows
PS: Unless a different compiler was meant, this thread could be closed.