CMP0001ΒΆ
CMAKE_BACKWARDS_COMPATIBILITY should no longer be used.
The behavior is to check CMAKE_BACKWARDS_COMPATIBILITY and present
it to the user. The NEW behavior is to ignore
CMAKE_BACKWARDS_COMPATIBILITY completely.
In CMake 2.4 and below the variable CMAKE_BACKWARDS_COMPATIBILITY was
used to request compatibility with earlier versions of CMake. In
CMake 2.6 and above all compatibility issues are handled by policies
and the cmake_policy() command. However, CMake must still check
CMAKE_BACKWARDS_COMPATIBILITY for projects written for CMake 2.4 and
below.
This policy was introduced in CMake version 2.6.0. CMake version
3.20.6 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.