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CMake/Help/command/cmake_minimum_required.rst
Nikita Nemkin c705279bae Help: Add .. versionadded directives to commands documentation
This change ony concerns directives that appear in the document body.

The guidelines for inserting version directives:

 * Baseline version is CMake 3.0, i.e. directives start at 3.1.
 * Always use `.. versionadded::` directive, avoid ad-hoc version
   references. Exception: policy pages.
 * For new command signatures, put `versionadded` on a separate line
   after the signature.
 * For a group of new signatures in a new document section,
   a single version note at the beginning of the section is sufficient.
 * For new options, put `versionadded` on a separate line before
   option description.
 * If all the option descriptions in the list are short one-liners,
   it's fine to put `versionadded` on the same line as the description.
 * If multiple option descriptions in close proximity would have
   the same ..versionadded directive, consider adding a single
   directive after the list, mentioning all added options.
 * For compact value lists and sub-option lists, put a single
  `versionadded` directive after the list mentioning all additions.
 * When a change is described in a single paragraph, put
   `versionadded` into that paragraph.
 * When only part of the paragraph has changed, separate the changed
   part if it doesn't break the flow. Otherwise, write a follow-up
   clarification paragraph and apply version directive to that.
 * When multiple version directives are close by, order earlier
   additions before later additions.
 * Indent related lists and code blocks to include them in the scope
   of `versionadded` directive.

Issue: #19715
2020-11-09 20:51:57 +05:00

72 lines
2.7 KiB
ReStructuredText

cmake_minimum_required
----------------------
Require a minimum version of cmake.
.. code-block:: cmake
cmake_minimum_required(VERSION <min>[...<max>] [FATAL_ERROR])
.. versionadded:: 3.12
The optional ``<max>`` version.
Sets the minimum required version of cmake for a project.
Also updates the policy settings as explained below.
``<min>`` and the optional ``<max>`` are each CMake versions of the form
``major.minor[.patch[.tweak]]``, and the ``...`` is literal.
If the running version of CMake is lower than the ``<min>`` required
version it will stop processing the project and report an error.
The optional ``<max>`` version, if specified, must be at least the
``<min>`` version and affects policy settings as described below.
If the running version of CMake is older than 3.12, the extra ``...``
dots will be seen as version component separators, resulting in the
``...<max>`` part being ignored and preserving the pre-3.12 behavior
of basing policies on ``<min>``.
The ``FATAL_ERROR`` option is accepted but ignored by CMake 2.6 and
higher. It should be specified so CMake versions 2.4 and lower fail
with an error instead of just a warning.
.. note::
Call the ``cmake_minimum_required()`` command at the beginning of
the top-level ``CMakeLists.txt`` file even before calling the
:command:`project` command. It is important to establish version
and policy settings before invoking other commands whose behavior
they may affect. See also policy :policy:`CMP0000`.
Calling ``cmake_minimum_required()`` inside a :command:`function`
limits some effects to the function scope when invoked. Such calls
should not be made with the intention of having global effects.
Policy Settings
^^^^^^^^^^^^^^^
The ``cmake_minimum_required(VERSION)`` command implicitly invokes the
:command:`cmake_policy(VERSION)` command to specify that the current
project code is written for the given range of CMake versions.
All policies known to the running version of CMake and introduced
in the ``<min>`` (or ``<max>``, if specified) version or earlier will
be set to use ``NEW`` behavior. All policies introduced in later
versions will be unset. This effectively requests behavior preferred
as of a given CMake version and tells newer CMake versions to warn
about their new policies.
When a ``<min>`` version higher than 2.4 is specified the command
implicitly invokes
.. code-block:: cmake
cmake_policy(VERSION <min>[...<max>])
which sets CMake policies based on the range of versions specified.
When a ``<min>`` version 2.4 or lower is given the command implicitly
invokes
.. code-block:: cmake
cmake_policy(VERSION 2.4[...<max>])
which enables compatibility features for CMake 2.4 and lower.