CMP0138
-------

.. versionadded:: 3.24

MSVC compilers use ``-ZI`` instead of ``/Zi`` for x86 and x64 by default.

When using MSVC C/C++ compilers in CMake 3.23 and below, debug information
format flag ``/Zi`` is added to :variable:`CMAKE_<LANG>_FLAGS_DEBUG` and
:variable:`CMAKE_<LANG>_FLAGS_RELWITHDEBINFO` by default. The ``/Zi`` flag
produces a separate PDB file that contains all the symbolic debugging
information for use with the debugger, however, it does not support Edit
and Continue feature in a debugging session.

CMake 3.24 and above adds ``-ZI`` to :variable:`CMAKE_<LANG>_FLAGS_DEBUG`
and :variable:`CMAKE_<LANG>_FLAGS_RELWITHDEBINFO` instead to enable Edit
and Continue by default.

This policy provides compatibility with projects that have not been updated
to expect the lack of warning flags. The policy setting takes effect as of
the first :command:`project` or :command:`enable_language` command that
initializes :variable:`CMAKE_<LANG>_FLAGS_DEBUG` and
:variable:`CMAKE_<LANG>_FLAGS_RELWITHDEBINFO` for a given language
``<LANG>`` using MSVC compilers.

.. note::

  Once the policy has taken effect at the top of a project for a given
  language, that choice must be used throughout the tree for that language.
  In projects that have nested projects in subdirectories, be sure to
  convert everything together.

The ``OLD`` behavior for this policy is to place ``/Zi`` in the default
:variable:`CMAKE_<LANG>_FLAGS_DEBUG` and
:variable:`CMAKE_<LANG>_FLAGS_RELWITHDEBINFO` cache entries. The ``NEW``
behavior for this policy is to place ``-ZI`` in the default cache entries.

This policy was introduced in CMake version 3.24. Use the
:command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly.
Unlike many policies, CMake version |release| does *not* warn
when this policy is not set and simply uses ``OLD`` behavior.

.. include:: DEPRECATED.txt