warn about ignored source files that would work when language is enabled
I have converted a project from a different build system over to CMake. Easy enough, just a ton of C, C++, and assembler files. The results were wrong and it took me a while to find out that CMake ignored the
.S files I passed to
add_executable() until I added
ASM to the list of languages. IMHO CMake should warn at least once when I add things that are ignored only because of missing languages. Ignoring a
.rc on non-Windows is perfectly fine, but other things like assembler files should be suspicious.