New in version 3.3.
Support new if() IN_LIST operator.
CMake 3.3 adds support for the new IN_LIST operator.
The OLD behavior for this policy is to ignore the IN_LIST operator. The NEW behavior is to interpret the IN_LIST operator.
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.
Note
The OLD behavior of a policy is deprecated by definition and may be removed in a future version of CMake.
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Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.19/policy/CMP0057.html