CMP0054
-------

Only interpret :command:`if` arguments as variables or keywords when unquoted.

CMake 3.1 and above no longer dereference variables or interpret keywords
in an :command:`if` command argument when it is a :ref:`Quoted Argument`
or a :ref:`Bracket Argument`.

The ``OLD`` behavior for this policy is to dereference variables and
interpret keywords even if they are quoted or bracketed.
The ``NEW`` behavior is to not dereference variables or interpret keywords
that have been quoted or bracketed.

This policy was introduced in CMake version 3.1.
CMake version |release| warns when the policy is not set and uses
``OLD`` behavior.  Use the :command:`cmake_policy` command to set
it to ``OLD`` or ``NEW`` explicitly.