CMP0081

Relative paths not allowed in LINK_DIRECTORIES target property.

CMake 3.12 and lower allowed the LINK_DIRECTORIES directory property to contain relative paths. The base path for such relative entries is not well defined. CMake 3.13 and later will issue a FATAL_ERROR if the LINK_DIRECTORIES target property (which is initialized by the LINK_DIRECTORIES directory property) contains a relative path.

The OLD behavior for this policy is not to warn about relative paths in the LINK_DIRECTORIES target property. The NEW behavior for this policy is to issue a FATAL_ERROR if LINK_DIRECTORIES contains a relative path.

This policy was introduced in CMake version 3.13. 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.