CMake Warning \(dev\) at CMP0028-WARN\.cmake:3 \(target_link_libraries\): Policy CMP0028 is not set: Double colon in target name means ALIAS or IMPORTED target. Run "cmake --help-policy CMP0028" for policy details. Use the cmake_policy command to set the policy and suppress this warning. Target "foo" links to: External::Library but the target was not found. Possible reasons include: ( \*[^ ]+)* Call Stack \(most recent call first\): CMakeLists\.txt:[0-9]+ \(include\) This warning is for project developers. Use -Wno-dev to suppress it.