PARENT_DIRECTORY

Source directory that added current subdirectory.

This read-only property specifies the source directory that added the current source directory as a subdirectory of the build. In the top-level directory the value is the empty-string.

© 2000–2020 Kitware, Inc. and Contributors
Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.18/prop_dir/PARENT_DIRECTORY.html