1 files changed, 21 insertions, 3 deletions
diff --git a/vendor/google.golang.org/protobuf/internal/impl/message_opaque.go b/vendor/google.golang.org/protobuf/internal/impl/message_opaque.go
index d407dd791..d7ec53f07 100644
--- a/vendor/google.golang.org/protobuf/internal/impl/message_opaque.go
+++ b/vendor/google.golang.org/protobuf/internal/impl/message_opaque.go
@@ -88,9 +88,7 @@ func opaqueInitHook(mi *MessageInfo) bool {
 	mi.oneofs = map[protoreflect.Name]*oneofInfo{}
 	for i := 0; i < mi.Desc.Oneofs().Len(); i++ {
 		od := mi.Desc.Oneofs().Get(i)
-		if !od.IsSynthetic() {
-			mi.oneofs[od.Name()] = makeOneofInfo(od, si.structInfo, mi.Exporter)
-		}
+		mi.oneofs[od.Name()] = makeOneofInfoOpaque(mi, od, si.structInfo, mi.Exporter)
 	}
 
 	mi.denseFields = make([]*fieldInfo, fds.Len()*2)
@@ -119,6 +117,26 @@ func opaqueInitHook(mi *MessageInfo) bool {
 	return true
 }
 
+func makeOneofInfoOpaque(mi *MessageInfo, od protoreflect.OneofDescriptor, si structInfo, x exporter) *oneofInfo {
+	oi := &oneofInfo{oneofDesc: od}
+	if od.IsSynthetic() {
+		fd := od.Fields().Get(0)
+		index, _ := presenceIndex(mi.Desc, fd)
+		oi.which = func(p pointer) protoreflect.FieldNumber {
+			if p.IsNil() {
+				return 0
+			}
+			if !mi.present(p, index) {
+				return 0
+			}
+			return od.Fields().Get(0).Number()
+		}
+		return oi
+	}
+	// Dispatch to non-opaque oneof implementation for non-synthetic oneofs.
+	return makeOneofInfo(od, si, x)
+}
+
 func (mi *MessageInfo) fieldInfoForMapOpaque(si opaqueStructInfo, fd protoreflect.FieldDescriptor, fs reflect.StructField) fieldInfo {
 	ft := fs.Type
 	if ft.Kind() != reflect.Map {