Installing MACOSX_BUNDLE targets requires a BUNDLE DESTINATION.
This policy determines whether the install(TARGETS) command must be given a BUNDLE DESTINATION when asked to install a target with the MACOSX_BUNDLE property set. CMake 2.4 and below did not distinguish application bundles from normal executables when installing targets. CMake 2.6 provides a BUNDLE option to the install(TARGETS) command that specifies rules specific to application bundles on the Mac. Projects should use this option when installing a target with the MACOSX_BUNDLE property set.
The OLD behavior for this policy is to fall back to the RUNTIME DESTINATION if a BUNDLE DESTINATION is not given. The NEW behavior for this policy is to produce an error if a bundle target is installed without a BUNDLE DESTINATION.
This policy was introduced in CMake version 2.6.0. CMake version warns when the policy is not set and uses OLD behavior. Use the cmake_policy command to set it to OLD or NEW explicitly.