CMP0046

Error on non-existent dependency in add_dependencies.

CMake 2.8.12 and lower silently ignored non-existent dependencies listed in the add_dependencies() command.

The OLD behavior for this policy is to silently ignore non-existent dependencies. The NEW behavior for this policy is to report an error if non-existent dependencies are listed in the add_dependencies() command.

This policy was introduced in CMake version 3.0. 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.