cppcheck only recognises .cpp, .cxx, .cc, .c++, and .c files.
If the package has C and/or C++ files with another extension please contact
cppcheck upstream.
Note: given the current way the source packages are checked, files
generated at build time (headers, .c files based on other data, etc) do
not exist at the time cppcheck is run. The code is never compiled.