CMP0155

.. versionadded:: 3.28

C++ sources in targets with at least C++20 are scanned for imports when supported.

CMake 3.27 and below assume that C++ sources do not import modules. CMake 3.28 and above prefer to assume that C++ sources in targets using C++20 or higher might import modules, and must be scanned before compiling, unless explicitly disabled. This policy provides compatibility for projects that use C++20 or higher, without modules, that have not been updated to turn off scanning, e.g., via the :variable:CMAKE_CXX_SCAN_FOR_MODULES variable. See the :manual:cmake-cxxmodules(7) manual for more details on C++ module support.

The OLD behavior for this policy is to assume that C++ 20 and newer sources do not import modules. The NEW behavior for this policy is to assume that C++ 20 and newer files may import modules if the compiler understands how to scan for their dependencies, and need to be scanned.

.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 3.28 .. |WARNS_OR_DOES_NOT_WARN| replace:: does not warn .. include:: include/STANDARD_ADVICE.rst

.. include:: include/DEPRECATED.rst