CMake can retrieve and use Git submodules as a regular subdirectory. This is an alternative to using FetchContent when the project team decides to use Git submodules instead of FetchContent. Create a file AddGitSubmodule.cmake:

Add Git submodule directories from CMakeLists.txt like:

include(AddGitSubmodule.cmake)

add_git_submodule(my_submod_dir)