Redundancy in C++ chiefly arises from textual inclusion as the mechanism for communicating about the capabilities of other modules. It's not because of a bad preprocessor or programming skill.
In my impression, most of the redundancy in the C world comes from the header/code seperation, i.e. all the signatures are repeated. Another level of redundancy was added by C++ templates where one quickly needs to write lengthy expressions, but the newer C++ standards resolved much of that thanks to the "auto a = b" type keyword or the "use X = Y" definitions.
Note that "CPY" addresses none of these issues.
This problem is avoided at no cost in Go, where an external tool can be used to get the same concise view of all of the function types that you like, without needing to manually create and update header files.
Most of my work these days is in JavaScript (Node).
I agree it is annoying to write, but I find well documented headers to be more usable than the other environments, if the project is large enough that I cannot read everything.