CMake Warning \(dev\) in CMakeLists.txt:
  Policy CMP0081 is not set: Relative paths not allowed in LINK_DIRECTORIES
  target property.  Run "cmake --help-policy CMP0081" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Found relative path while evaluating link directories of "foo":

    "../lib"

This warning is for project developers.  Use -Wno-dev to suppress it.