[CMake] What's the best way to support additional compilers for an "official" CMake language such as Fortran

[Brad King]

Arjen Markus wrote:
> I did it this way just now too, but I found out that the intermediate
> files are stored in the directory containing the CMakeLists.txt file!

Somehow a CMakeCache.txt file must have ended up in your source tree.
Once an in-source build is done it is impossible to do out-of-source.
Get a fresh tree from version control and try again.

-Brad