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Diffstat (limited to 'Help/variable/PROJECT_IS_TOP_LEVEL.rst')
-rw-r--r-- | Help/variable/PROJECT_IS_TOP_LEVEL.rst | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Help/variable/PROJECT_IS_TOP_LEVEL.rst b/Help/variable/PROJECT_IS_TOP_LEVEL.rst new file mode 100644 index 000000000..ad61fecc0 --- /dev/null +++ b/Help/variable/PROJECT_IS_TOP_LEVEL.rst @@ -0,0 +1,31 @@ +PROJECT_IS_TOP_LEVEL +-------------------- + +.. versionadded:: 3.21 + +A boolean variable indicating whether :command:`project` was called in a top +level ``CMakeLists.txt`` file. + +Some modules should only be included as part of the top level +``CMakeLists.txt`` file to not cause unintended side effects in the build +tree, and this variable can be used to conditionally execute such code. For +example, consider the :module:`CTest` module, which creates targets and +options: + +.. code-block:: cmake + + project(MyProject) + ... + if(PROJECT_IS_TOP_LEVEL) + include(CTest) + endif() + +The variable value will be true in: + +* the top-level directory of the project +* the top-level directory of an external project added by :module:`ExternalProject` + +The variable value will be false in: + +* a directory added by :command:`add_subdirectory` +* a directory added by :module:`FetchContent` |