# CMP0000

A minimum required CMake version must be specified.

CMake requires that projects specify the version of CMake to which they have been written. This policy has been put in place so users trying to build the project may be told when they need to update their CMake. Specifying a version also helps the project build with CMake versions newer than that specified. Use the `cmake_minimum_required()` command at the top of your main `CMakeLists.txt` file:

    cmake_minimum_required(VERSION <major>.<minor>)

where `<major>.<minor>` is the version of CMake you want to support (such as `3.14`). The command will ensure that at least the given version of CMake is running and help newer versions be compatible with the project. See documentation of `cmake_minimum_required()` for details.

Note that the command invocation must appear in the `CMakeLists.txt` file itself; a call in an included file is not sufficient. However, the `cmake_policy()` command may be called to set policy `CMP0000` to `OLD` or `NEW` behavior explicitly. The `OLD` behavior is to silently ignore the missing invocation. The `NEW` behavior is to issue an error instead of a warning. An included file may set `CMP0000` explicitly to affect how this policy is enforced for the main `CMakeLists.txt` file.

This policy was introduced in CMake version 2.6.0.

Note

The `OLD` behavior of a policy is `deprecated by definition` and may be removed in a future version of CMake.