While here, change the params to be easier to understand: "t" is now
always the type being updated, and "underlying" is now used to
represent the underlying type.
Updates #33658.
Change-Id: Iabb64414ca3abaa8c780e4c9093e0c77b76fabf9
Reviewed-on: https://go-review.googlesource.com/c/go/+/192724
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Robert Griesemer <gri@golang.org>