Set the minimum required version of cmake for a project and update Policy Settings to match the version given:
cmake_minimum_required(VERSION major.minor[.patch[.tweak]] [FATAL_ERROR])
If the current version of CMake is lower than that required it will stop processing the project and report an error.
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.
cmake_minimum_required() command at the beginning of
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
cmake_minimum_required() inside a
limits some effects to the function scope when invoked. Such calls
should not be made with the intention of having global effects.
cmake_minimum_required(VERSION) command implicitly invokes the
cmake_policy(VERSION) command to specify that the current
project code is written for the given version of CMake.
All policies introduced in the specified version or earlier will be
set to use NEW behavior. All policies introduced after the specified
version 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 version higher than 2.4 is specified the command implicitly invokes:
which sets the cmake policy version level to the version specified. When version 2.4 or lower is given the command implicitly invokes:
which enables compatibility features for CMake 2.4 and lower.