Dunno, but it makes little sense to me. For you can have an anonymous reference. (no name) or you can have a reference to a scalar that has more than one name (using Scalar::Alias or similar)

So the question "which is the name of the var referenced by $x" may have zero, one or more than one answer.

Is yours an academic question or have you a specific need in mind? Maybe it is an XY Problem.