<PROJECT-NAME>_IS_TOP_LEVEL

New in version 3.21.

A boolean variable indicating whether the named project was called in a top level CMakeLists.txt file.

To obtain the value from the most recent call to project() in the current directory scope or above, see the PROJECT_IS_TOP_LEVEL variable.

The variable value will be true in:

• the top-level directory of the project

• the top-level directory of an external project added by ExternalProject

The variable value will be false in:

• a directory added by add_subdirectory()

• a directory added by FetchContent