[release-branch.go1.21] go/types, types2: use exact unification when comparing interface methods
Irrespective of whether unification is exact or inexact, method
signatures of interfaces must always match exactly: a type never
satisfies/implements an interface if relevant method signatures
are different (i.e., not identical, possibly after substitution).
Fixes #61959.
Change-Id: I20c0aa28ac86e2edec615b40f2269938e4a96938
Reviewed-on: https://go-review.googlesource.com/c/go/+/519435
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com> Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/519416
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>