CMP0039

Utility targets may not have link dependencies.

CMake 2.8.12 and lower allowed using utility targets in the left hand side position of the target_link_libraries() command. This is an indicator of a bug in user code.

The OLD behavior for this policy is to ignore attempts to set the link libraries of utility targets. The NEW behavior for this policy is to report an error if an attempt is made to set the link libraries of a utility target.

This policy was introduced in CMake version 3.0. CMake version 3.15.7 warns when the policy is not set and uses OLD behavior. Use the cmake_policy() command to set it to OLD or NEW explicitly.