CMAKE_SOURCE_DIR

The path to the top level of the source tree.

This is the full path to the top level of the current CMake source tree. For an in-source build, this would be the same as :variable:CMAKE_BINARY_DIR.

When run in :option:cmake -P script mode, CMake sets the variables :variable:CMAKE_BINARY_DIR, CMAKE_SOURCE_DIR, :variable:CMAKE_CURRENT_BINARY_DIR and :variable:CMAKE_CURRENT_SOURCE_DIR to the current working directory.

Modifying CMAKE_SOURCE_DIR has undefined behavior.