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

Imported interfaces don't have position information for embedded types.
When computing the type set of such interfaces, doing a version check
may fail because it will rely on the Go version of the current package.

We must not do a version check for features of types from imported
packages - those types have already been typechecked and are "correct".
The version check code does look at packages to avoid such incorrect
version checks, but we don't have the package information available
in an interface type (divorced from its object).

Instead, for now rely on the fact that imported interfaces don't have
position information for embedded types: if the position is unknown,
don't do a version check.

We may want to assert that positions are known in all other cases,
but since this is an older release, don't add such additional changes
to avoid introducing other bugs.

Fixes #66064.

Change-Id: I773d57e5410c3d4a911ab3e018b3233c2972b3c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/571075
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Griesemer <gri@google.com>

diff --git a/src/cmd/compile/internal/types2/typeset.go b/src/cmd/compile/internal/types2/typeset.go
index 8d33597ffd90a6b270d8550d233e7d1b61e24ba3..14039ac9d6184dc1e82015220d72f7ca1f970eae 100644 (file)
--- a/src/cmd/compile/internal/types2/typeset.go
+++ b/src/cmd/compile/internal/types2/typeset.go
@@ -255,9 +255,8 @@ 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
-               // and also for interface copies after substitution (but
-               // in that case we don't need to report errors again).
+               // The embedding position is nil for imported interfaces.
+               // We don't need to do version checks in those cases.
                var pos syntax.Pos // embedding position
                if ityp.embedPos != nil {
                        pos = (*ityp.embedPos)[i]
@@ -270,7 +269,7 @@ 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 check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(pos, go1_18, "embedding constraint interface %s", typ) {
+                       if pos.IsKnown() && check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(pos, go1_18, "embedding constraint interface %s", typ) {
                                continue
                        }
                        comparable = tset.comparable
@@ -279,7 +278,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
                        }
                        terms = tset.terms
                case *Union:
-                       if check != nil && !check.verifyVersionf(pos, go1_18, "embedding interface element %s", u) {
+                       if pos.IsKnown() && check != nil && !check.verifyVersionf(pos, go1_18, "embedding interface element %s", u) {
                                continue
                        }
                        tset := computeUnionTypeSet(check, unionSets, pos, u)
@@ -293,7 +292,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
                        if u == Typ[Invalid] {
                                continue
                        }
-                       if check != nil && !check.verifyVersionf(pos, go1_18, "embedding non-interface type %s", typ) {
+                       if pos.IsKnown() && 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 4cd118a2265535f68508ddf3e662d8fc14c398c9..a7d4485d0ef7230f706940bc8cf37ca724841d4d 100644 (file)
--- a/src/go/types/typeset.go
+++ b/src/go/types/typeset.go
@@ -253,9 +253,8 @@ 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
-               // and also for interface copies after substitution (but
-               // in that case we don't need to report errors again).
+               // The embedding position is nil for imported interfaces.
+               // We don't need to do version checks in those cases.
                var pos token.Pos // embedding position
                if ityp.embedPos != nil {
                        pos = (*ityp.embedPos)[i]
@@ -268,7 +267,7 @@ 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 check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(atPos(pos), go1_18, "embedding constraint interface %s", typ) {
+                       if pos.IsValid() && check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(atPos(pos), go1_18, "embedding constraint interface %s", typ) {
                                continue
                        }
                        comparable = tset.comparable
@@ -277,7 +276,7 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
                        }
                        terms = tset.terms
                case *Union:
-                       if check != nil && !check.verifyVersionf(atPos(pos), go1_18, "embedding interface element %s", u) {
+                       if pos.IsValid() && check != nil && !check.verifyVersionf(atPos(pos), go1_18, "embedding interface element %s", u) {
                                continue
                        }
                        tset := computeUnionTypeSet(check, unionSets, pos, u)
@@ -291,7 +290,7 @@ func computeInterfaceTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_T
                        if u == Typ[Invalid] {
                                continue
                        }
-                       if check != nil && !check.verifyVersionf(atPos(pos), go1_18, "embedding non-interface type %s", typ) {
+                       if pos.IsValid() && 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
new file mode 100644 (file)
index 0000000..d4a3617
--- /dev/null
+++ b/src/internal/types/testdata/fixedbugs/issue66064.go
@@ -0,0 +1,15 @@
+// -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
+}