CMake Error: CMake can not determine linker language for target: [XYZ]

Just stumpled over a strange problem using CMake. A usually straight forward setup adding a 2nd executable lead to an error like this:

-- Configuring done
CMake Error: CMake can not determine linker language for target: Tests
-- Generating done

This might be related to me now using cmake 3.14 as minimum in the CMakeLists.txt-file or might be related to using CPM as CMake-internal package-manager (which requires 3.14). Not quite sure.

To make the long story short. I fixed it by adding following to the specific target:

    set_target_properties(Tests PROPERTIES LINKER_LANGUAGE CXX)

Reference: https://stackoverflow.com/questions/56462415/cmake-error-cannot-determine-link-language-for-target