CMake/Help/variable/CMAKE_INCLUDE_CURRENT_DIR.rst

CMAKE_INCLUDE_CURRENT_DIR
-------------------------

Automatically add the current source- and build directories to the include path.

If this variable is enabled, CMake automatically adds in each
directory ${CMAKE_CURRENT_SOURCE_DIR} and ${CMAKE_CURRENT_BINARY_DIR}
to the include path for this directory.  These additional include
directories do not propagate down to subdirectories.  This is useful
mainly for out-of-source builds, where files generated into the build
tree are included by files located in the source tree.

By default CMAKE_INCLUDE_CURRENT_DIR is OFF.