[release-branch.go1.21] Revert "go/types, types2: don't do version checks for embedded types of imported interfaces"

This reverts CL 571075.

Reason for revert: We might want to do a security-only minor release. Back off the release branch to a clean state from the previous minor release. Sorry for the inconvenience.

Change-Id: Ifc8c7e00e6faea3aa547b883eed44180ddb447de
Reviewed-on: https://go-review.googlesource.com/c/go/+/571355
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>

3 files changed, 12 insertions, 25 deletions

diff --git a/src/cmd/compile/internal/types2/typeset.go b/src/cmd/compile/internal/types2/typeset.go
index 14039ac9d6..8d33597ffd 100644
--- a/src/cmd/compile/internal/types2/typeset.go
+++ b/src/cmd/compile/internal/types2/typeset.go
@@ -255,8 +255,9 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 	allTerms := allTermlist
 	allComparable := false
 	for i, typ := range ityp.embeddeds {
-		// The embedding position is nil for imported interfaces.
-		// We don't need to do version checks in those cases.
+		// The embedding position is nil for imported interfaces
+		// and also for interface copies after substitution (but
+		// in that case we don't need to report errors again).
 		var pos syntax.Pos // embedding position
 		if ityp.embedPos != nil {
 			pos = (*ityp.embedPos)[i]
@@ -269,7 +270,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 			assert(!isTypeParam(typ))
 			tset := computeInterfaceTypeSet(check, pos, u)
 			// If typ is local, an error was already reported where typ is specified/defined.
-			if pos.IsKnown() && check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(pos, go1_18, "embedding constraint interface %s", typ) {
+			if check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(pos, go1_18, "embedding constraint interface %s", typ) {
 				continue
 			}
 			comparable = tset.comparable
@@ -278,7 +279,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 			}
 			terms = tset.terms
 		case *Union:
-			if pos.IsKnown() && check != nil && !check.verifyVersionf(pos, go1_18, "embedding interface element %s", u) {
+			if check != nil && !check.verifyVersionf(pos, go1_18, "embedding interface element %s", u) {
 				continue
 			}
 			tset := computeUnionTypeSet(check, unionSets, pos, u)
@@ -292,7 +293,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 			if u == Typ[Invalid] {
 				continue
 			}
-			if pos.IsKnown() && check != nil && !check.verifyVersionf(pos, go1_18, "embedding non-interface type %s", typ) {
+			if check != nil && !check.verifyVersionf(pos, go1_18, "embedding non-interface type %s", typ) {
 				continue
 			}
 			terms = termlist{{false, typ}}
diff --git a/src/go/types/typeset.go b/src/go/types/typeset.go
index a7d4485d0e..4cd118a226 100644
--- a/src/go/types/typeset.go
+++ b/src/go/types/typeset.go
@@ -253,8 +253,9 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
 	allTerms := allTermlist
 	allComparable := false
 	for i, typ := range ityp.embeddeds {
-		// The embedding position is nil for imported interfaces.
-		// We don't need to do version checks in those cases.
+		// The embedding position is nil for imported interfaces
+		// and also for interface copies after substitution (but
+		// in that case we don't need to report errors again).
 		var pos token.Pos // embedding position
 		if ityp.embedPos != nil {
 			pos = (*ityp.embedPos)[i]
@@ -267,7 +268,7 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
 			assert(!isTypeParam(typ))
 			tset := computeInterfaceTypeSet(check, pos, u)
 			// If typ is local, an error was already reported where typ is specified/defined.
-			if pos.IsValid() && check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(atPos(pos), go1_18, "embedding constraint interface %s", typ) {
+			if check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(atPos(pos), go1_18, "embedding constraint interface %s", typ) {
 				continue
 			}
 			comparable = tset.comparable
@@ -276,7 +277,7 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
 			}
 			terms = tset.terms
 		case *Union:
-			if pos.IsValid() && check != nil && !check.verifyVersionf(atPos(pos), go1_18, "embedding interface element %s", u) {
+			if check != nil && !check.verifyVersionf(atPos(pos), go1_18, "embedding interface element %s", u) {
 				continue
 			}
 			tset := computeUnionTypeSet(check, unionSets, pos, u)
@@ -290,7 +291,7 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
 			if u == Typ[Invalid] {
 				continue
 			}
-			if pos.IsValid() && check != nil && !check.verifyVersionf(atPos(pos), go1_18, "embedding non-interface type %s", typ) {
+			if check != nil && !check.verifyVersionf(atPos(pos), go1_18, "embedding non-interface type %s", typ) {
 				continue
 			}
 			terms = termlist{{false, typ}}
diff --git a/src/internal/types/testdata/fixedbugs/issue66064.go b/src/internal/types/testdata/fixedbugs/issue66064.go
deleted file mode 100644
index d4a361754b..0000000000
--- a/src/internal/types/testdata/fixedbugs/issue66064.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// -lang=go1.16
-
-// Copyright 2024 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.
-
-//go:build go1.21
-
-package main
-
-import "slices"
-
-func main() {
-	_ = slices.Clone([]string{}) // no error should be reported here
-}