I suggest rephrasing this sentence since it currently makes assumption what the package might do / might want to do, maybe: > Check the 'LANGUAGES' argument of the 'project()' call to make sure CXX is not excluded.

This logic can never be triggered. The macro `_generate_function_if_no_cxx_language` already contains a `return()` statement which ends the file when it is invoked in line 4.

This needs to include other public functions from this file, e.g. `catkin_add_executable_with_gtest`. The same is probably needed above in `_generate_function_if_testing_is_disabled`.