#22075 makes it such that NumMethod no longer counts unexported methods for interfaces (and by implication the inability to obtain information about unexported methods).

One use case this breaks is https://github.com/google/go-cmp/blob/566225a2554cf156c7af1006dc3a0940e1e02b09/cmp/internal/value/name.go#L133-L146, where the goal is to print fully-qualified type information about a Go type (i.e., reflect.Type.String is insufficiently detailed). With the NumMethod change, I can no longer print unnamed interfaces in a way where users can tell that they are different.

I propose we add a reflect.Type.QualifiedString method that ensures the following property:

t1.QualifiedString() == t2.QualifiedString() if and only if t1 == t2

I don't have any strong preferences for the content of the string other than it be a humanly readable representation of the type. If the output is Go syntax, perhaps the method can be called GoString.

\cc @mdempsky