CMAKE_POLICY_WARNING_CMP<NNNN>
Explicitly enable or disable the warning when CMake Policy CMP<NNNN> is not set. This is meaningful only for the few policies that do not warn by default:
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CMAKE_POLICY_WARNING_CMP0025controls the warning for policyCMP0025.
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CMAKE_POLICY_WARNING_CMP0047controls the warning for policyCMP0047.
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CMAKE_POLICY_WARNING_CMP0056controls the warning for policyCMP0056.
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CMAKE_POLICY_WARNING_CMP0060controls the warning for policyCMP0060.
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CMAKE_POLICY_WARNING_CMP0065controls the warning for policyCMP0065.
This variable should not be set by a project in CMake code. Project developers running CMake may set this variable in their cache to enable the warning (e.g. -DCMAKE_POLICY_WARNING_CMP<NNNN>=ON). Alternatively, running cmake(1) with the --debug-output, --trace, or --trace-expand option will also enable the warning.
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Licensed under the BSD 3-clause License.
    https://cmake.org/cmake/help/v3.5/variable/CMAKE_POLICY_WARNING_CMPNNNN.html