CMP0203
-------

.. versionadded:: 4.2

``_WINDLL`` is defined for shared libraries targeting the MSVC ABI.

In CMake 4.1 and below, :ref:`Visual Studio Generators` compile sources in
shared libraries with ``_WINDLL`` defined due to behavior of Visual Studio
itself.  The preprocessor definition is not modeled by CMake and is therefore
not added by other generators, such as :generator:`Ninja`.

CMake 4.2 and above, when targeting the MSVC ABI, prefer to compile sources
in shared libraries with ``_WINDLL`` defined by all generators.
This policy provides compatibility with projects that have not been updated
to be aware of the definition.  Its setting is recorded by each target as
it is created, and affects compilation of sources in that target.

The ``OLD`` behavior for this policy does not model the ``_WINDLL``
preprocessor definition in CMake itself.  The ``NEW`` behavior for this
policy adds the ``_WINDLL`` preprocessor definition to sources in shared
libraries when targeting the MSVC ABI.

.. |INTRODUCED_IN_CMAKE_VERSION| replace:: 4.2
.. |WARNS_OR_DOES_NOT_WARN| replace:: does *not* warn
.. include:: include/STANDARD_ADVICE.rst

.. include:: include/DEPRECATED.rst
