CMP0059

Do not treat DEFINITIONS as a built-in directory property.

CMake 3.3 and above no longer make a list of definitions available through the DEFINITIONS directory property. The COMPILE_DEFINITIONS directory property may be used instead.

The OLD behavior for this policy is to provide the list of flags given so far to the add_definitions() command. The NEW behavior is to behave as a normal user-defined directory property.

This policy was introduced in CMake version 3.3. CMake version 3.19.0-rc3 warns when the policy is not set and uses OLD behavior. Use the cmake_policy() command to set it to OLD or NEW explicitly.