cmake_minimum_required¶
Require a minimum version of cmake.
cmake_minimum_required(VERSION <min>[...<policy_max>] [FATAL_ERROR])
New in version 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
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
project() command. It is important to establish version
and policy settings before invoking other commands whose behavior
they may affect. See also policy CMP0000.
Calling cmake_minimum_required() inside a function()
limits some effects to the function scope when invoked. For example,
the 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¶
The cmake_minimum_required(VERSION) command implicitly invokes the
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
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
cmake_policy(VERSION 2.4[...<max>])
which enables compatibility features for CMake 2.4 and lower.