| cmake_minimum_required | |
| ---------------------- | |
| Require a minimum version of cmake. | |
| .. code-block:: cmake | |
| cmake_minimum_required(VERSION <min>[...<policy_max>] [FATAL_ERROR]) | |
| .. versionadded:: 3.12 | |
| The optional ``<policy_max>`` version. | |
| Sets the minimum required version of cmake for a project. | |
| Also updates the policy settings as explained below. | |
| ``<min>`` and the optional ``<policy_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 ``<policy_max>`` version, if specified, must be at least the | |
| ``<min>`` version and affects policy settings as described in `Policy Settings`_. | |
| 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>``. | |
| This command will set the value of the | |
| :variable:`CMAKE_MINIMUM_REQUIRED_VERSION` variable to ``<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. For example, | |
| the :variable:`CMAKE_MINIMUM_REQUIRED_VERSION` variable won't be set | |
| in the calling scope. Functions do not introduce their own policy | |
| scope though, so policy settings of the caller *will* be affected | |
| (see below). Due to this mix of things that do and do not affect the | |
| calling scope, calling ``cmake_minimum_required()`` inside a function | |
| is generally discouraged. | |
| .. _`Policy Settings`: | |
| 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. | |
| .. include:: DEPRECATED_POLICY_VERSIONS.txt | |
| See Also | |
| ^^^^^^^^ | |
| * :command:`cmake_policy` | |