For example, if `trait Foo: Bar`, and we try to call a method from `Bar` on `dyn Foo`, encode the callsite as passing a `dyn Bar`, not a `dyn Foo`.
For example, if `trait Foo: Bar`, and we try to call a method from `Bar` on `dyn Foo`, encode the callsite as passing a `dyn Bar`, not a `dyn Foo`.