<PROJECT-NAME>_IS_TOP_LEVELΒΆ
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
- a directory added by - add_subdirectory()that does not also contain a- project()call
- a directory added by - FetchContent_MakeAvailable(), if the fetched content does not contain a- project()call
The variable value will be false in:
- a directory added by - add_subdirectory()that also contains a- project()call
- a directory added by - FetchContent_MakeAvailable(), if the fetched content contains a- project()call
