Get a property of
get_directory_property(<variable> [DIRECTORY <dir>] <prop-name>)
Store a property of directory scope in the named variable. If the
property is not defined the empty-string is returned. The
argument specifies another directory from which to retrieve the
property value. The specified directory must have already been
traversed by CMake.
get_directory_property(<variable> [DIRECTORY <dir>] DEFINITION <var-name>)
Get a variable definition from a directory. This form is useful to get a variable definition from another directory.
See also the more general