Targets may not link directly to themselves.
CMake 2.8.12 and lower allowed a build target to link to itself directly with
target_link_libraries() call. This is an indicator of a bug in
OLD behavior for this policy is to ignore targets which list themselves
in their own link implementation. The
NEW behavior for this policy is to
report an error if a target attempts to link to itself.
This policy was introduced in CMake version 3.0. CMake version
3.26.2 warns when the policy is not set and uses
OLD behavior. Use
cmake_policy() command to set it to
OLD behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.