CMake/Help/policy/CMP0208.rst

CMP0208
-------

.. versionadded:: 4.3

:command:`export(EXPORT)` does not allow empty arguments.

In CMake 4.2 and below, the :command:`export(EXPORT)` command silently
accepted ``NAMESPACE``, ``FILE`` or ``CXX_MODULES_DIRECTORY`` arguments with
empty or missing values.

CMake 4.3 and above issue a diagnostic if any of these keywords are present
without an associated value, or of the value given to ``FILE`` or
``CXX_MODULES_DIRECTORY`` is empty.  (``NAMESPACE`` is allowed to have an empty
value, but an empty value must be quoted.)  A diagnostic is also issued
immediately if the value of ``EXPORT`` is missing or empty.  (Previously, this
would result in an error at generate-time because no export set whose name is
empty can exist.)

This policy provides compatibility with projects which may have relied on the
previous lack of enforcement.  The ``OLD`` behavior for this policy permits
these keywords to be present without an accompanying value, or to be given an
empty value.  The ``NEW`` behavior requires that a value be given, and that
the value (except for ``NAMESPACE``) is non-empty.

.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 4.3
.. |WARNS_OR_DOES_NOT_WARN| replace:: warns
.. include:: include/STANDARD_ADVICE.rst

.. include:: include/DEPRECATED.rst