go/types, types2: typecheck cases even if switch expression is invalid
Rather than returning right away when the switch expression is invalid,
continue type checking the type switch case.
The code was already written to be able to deal with an invalid switch
expression but it returned early nevertheless. Remove the early return
and rewrite the switch expression test slightly to better control the
scope of the x operand, leading to cleaner code.
In the process replace a tricky use of the x operand with a use of the
sx operand (plus guard, since sx may be nil if invalid).
Fixes #67962.
Change-Id: I1dc08d10078753c68449637622beb4018ed23803
Reviewed-on: https://go-review.googlesource.com/c/go/+/592555 Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>