go/types, types2: use strict comparability for type set intersection

Fixes #57486.

Change-Id: I4b71199a724718886ce6d7a49e96a9ebdcbcf737
Reviewed-on: https://go-review.googlesource.com/c/go/+/459816
Run-TryBot: Robert Griesemer <[email protected]>
Auto-Submit: Robert Griesemer <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Auto-Submit: Robert Griesemer <[email protected]>
Reviewed-by: Robert Findley <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>
Run-TryBot: Robert Griesemer <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: griesemer

src/cmd/compile/internal/types2/typeset.go

@@ -352,7 +352,7 @@ func intersectTermLists(xterms termlist, xcomp bool, yterms termlist, ycomp bool
 		i := 0
 		for _, t := range terms {
 			assert(t.typ != nil)
-			if Comparable(t.typ) {
+			if comparable(t.typ, false /* strictly comparable */, nil, nil) {
 				terms[i] = t
 				i++
 			}

src/go/types/typeset.go

@@ -350,7 +350,7 @@ func intersectTermLists(xterms termlist, xcomp bool, yterms termlist, ycomp bool
 		i := 0
 		for _, t := range terms {
 			assert(t.typ != nil)
-			if Comparable(t.typ) {
+			if comparable(t.typ, false /* strictly comparable */, nil, nil) {
 				terms[i] = t
 				i++
 			}

src/internal/types/testdata/fixedbugs/issue57486.go

@@ -0,0 +1,29 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type C1 interface {
+	comparable
+}
+
+type C2 interface {
+	comparable
+	[2]any | int
+}
+
+func G1[T C1](t T) { _ = t == t }
+func G2[T C2](t T) { _ = t == t }
+
+func F1[V [2]any](v V) {
+	_ = G1[V /* ERROR "V does not implement comparable" */]
+	_ = G1[[2]any]
+	_ = G1[int]
+}
+
+func F2[V [2]any](v V) {
+	_ = G2[V /* ERROR "V does not implement C2" */]
+	_ = G2[[ /* ERROR "\[2\]any does not implement C2 \(\[2\]any missing in int\)" */ 2]any]
+	_ = G2[int]
+}