spec: adjust rule for type parameter on RHS of alias declaration
Per discussion on issue #75885, a type parameter on the RHS of an alias
declaration must not be declared in the same declaration (but it may be
declared by an enclosing function). This relaxes the spec slightly and
allows for (pre-existing) test cases.
Add a corresponding check to the type checker (there was no check for
type parameters on the RHS of alias declarations at all, before).
Fixes #75884.
Fixes #75885.
Change-Id: I1e5675978e6423d626c068829d4bf5e90035ea82
Reviewed-on: https://go-review.googlesource.com/c/go/+/721820
Auto-Submit: Robert Griesemer <gri@google.com> Reviewed-by: Robert Griesemer <gri@google.com> Reviewed-by: Mark Freeman <markfreeman@google.com> Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>