cmd/cloner, cmd/viewer, util/codegen: add support for aliases of cloneable types

We have several checked type assertions to *types.Named in both cmd/cloner and cmd/viewer.
As Go 1.23 updates the go/types package to produce Alias type nodes for type aliases,
these type assertions no longer work as expected unless the new behavior is disabled
with gotypesalias=0.

In this PR, we add codegen.NamedTypeOf(t types.Type), which functions like t.(*types.Named)
but also unrolls type aliases. We then use it in place of type assertions in the cmd/cloner and
cmd/viewer packages where appropriate.

We also update type switches to include *types.Alias alongside *types.Named in relevant cases,
remove *types.Struct cases when switching on types.Type.Underlying and update the tests
with more cases where type aliases can be used.

Updates #13224
Updates #12912

Signed-off-by: Nick Khyl <nickk@tailscale.com>

cmd/cloner/cloner.go

@@ -115,7 +115,7 @@ func gen(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named) {
 		if !codegen.ContainsPointers(ft) || codegen.HasNoClone(t.Tag(i)) {
 			continue
 		}
-		if named, _ := ft.(*types.Named); named != nil {
+		if named, _ := codegen.NamedTypeOf(ft); named != nil {
 			if codegen.IsViewType(ft) {
 				writef("dst.%s = src.%s", fname, fname)
 				continue
@@ -161,7 +161,7 @@ func gen(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named) {
 		case *types.Pointer:
 			base := ft.Elem()
 			hasPtrs := codegen.ContainsPointers(base)
-			if named, _ := base.(*types.Named); named != nil && hasPtrs {
+			if named, _ := codegen.NamedTypeOf(base); named != nil && hasPtrs {
 				writef("dst.%s = src.%s.Clone()", fname, fname)
 				continue
 			}

cmd/viewer/tests/tests.go

@@ -206,11 +206,25 @@ type StructWithContainers struct {
 type (
 	StructWithPtrsAlias        = StructWithPtrs
 	StructWithoutPtrsAlias     = StructWithoutPtrs
+	StructWithPtrsAliasView    = StructWithPtrsView
+	StructWithoutPtrsAliasView = StructWithoutPtrsView
 )
 
 type StructWithTypeAliasFields struct {
 	WithPtr    StructWithPtrsAlias
 	WithoutPtr StructWithoutPtrsAlias
+
+	WithPtrByPtr    *StructWithPtrsAlias
+	WithoutPtrByPtr *StructWithoutPtrsAlias
+
+	SliceWithPtrs    []*StructWithPtrsAlias
+	SliceWithoutPtrs []*StructWithoutPtrsAlias
+
+	MapWithPtrs    map[string]*StructWithPtrsAlias
+	MapWithoutPtrs map[string]*StructWithoutPtrsAlias
+
+	MapOfSlicesWithPtrs    map[string][]*StructWithPtrsAlias
+	MapOfSlicesWithoutPtrs map[string][]*StructWithoutPtrsAlias
 }
 
 type integer = constraints.Integer

cmd/viewer/tests/tests_clone.go

@@ -450,7 +450,63 @@ func (src *StructWithTypeAliasFields) Clone() *StructWithTypeAliasFields {
 	}
 	dst := new(StructWithTypeAliasFields)
 	*dst = *src
-	panic("TODO: WithPtr (*types.Struct)")
+	dst.WithPtr = *src.WithPtr.Clone()
+	dst.WithPtrByPtr = src.WithPtrByPtr.Clone()
+	if dst.WithoutPtrByPtr != nil {
+		dst.WithoutPtrByPtr = ptr.To(*src.WithoutPtrByPtr)
+	}
+	if src.SliceWithPtrs != nil {
+		dst.SliceWithPtrs = make([]*StructWithPtrsAlias, len(src.SliceWithPtrs))
+		for i := range dst.SliceWithPtrs {
+			if src.SliceWithPtrs[i] == nil {
+				dst.SliceWithPtrs[i] = nil
+			} else {
+				dst.SliceWithPtrs[i] = src.SliceWithPtrs[i].Clone()
+			}
+		}
+	}
+	if src.SliceWithoutPtrs != nil {
+		dst.SliceWithoutPtrs = make([]*StructWithoutPtrsAlias, len(src.SliceWithoutPtrs))
+		for i := range dst.SliceWithoutPtrs {
+			if src.SliceWithoutPtrs[i] == nil {
+				dst.SliceWithoutPtrs[i] = nil
+			} else {
+				dst.SliceWithoutPtrs[i] = ptr.To(*src.SliceWithoutPtrs[i])
+			}
+		}
+	}
+	if dst.MapWithPtrs != nil {
+		dst.MapWithPtrs = map[string]*StructWithPtrsAlias{}
+		for k, v := range src.MapWithPtrs {
+			if v == nil {
+				dst.MapWithPtrs[k] = nil
+			} else {
+				dst.MapWithPtrs[k] = v.Clone()
+			}
+		}
+	}
+	if dst.MapWithoutPtrs != nil {
+		dst.MapWithoutPtrs = map[string]*StructWithoutPtrsAlias{}
+		for k, v := range src.MapWithoutPtrs {
+			if v == nil {
+				dst.MapWithoutPtrs[k] = nil
+			} else {
+				dst.MapWithoutPtrs[k] = ptr.To(*v)
+			}
+		}
+	}
+	if dst.MapOfSlicesWithPtrs != nil {
+		dst.MapOfSlicesWithPtrs = map[string][]*StructWithPtrsAlias{}
+		for k := range src.MapOfSlicesWithPtrs {
+			dst.MapOfSlicesWithPtrs[k] = append([]*StructWithPtrsAlias{}, src.MapOfSlicesWithPtrs[k]...)
+		}
+	}
+	if dst.MapOfSlicesWithoutPtrs != nil {
+		dst.MapOfSlicesWithoutPtrs = map[string][]*StructWithoutPtrsAlias{}
+		for k := range src.MapOfSlicesWithoutPtrs {
+			dst.MapOfSlicesWithoutPtrs[k] = append([]*StructWithoutPtrsAlias{}, src.MapOfSlicesWithoutPtrs[k]...)
+		}
+	}
 	return dst
 }
 
@@ -458,6 +514,14 @@ func (src *StructWithTypeAliasFields) Clone() *StructWithTypeAliasFields {
 var _StructWithTypeAliasFieldsCloneNeedsRegeneration = StructWithTypeAliasFields(struct {
 	WithPtr                StructWithPtrsAlias
 	WithoutPtr             StructWithoutPtrsAlias
+	WithPtrByPtr           *StructWithPtrsAlias
+	WithoutPtrByPtr        *StructWithoutPtrsAlias
+	SliceWithPtrs          []*StructWithPtrsAlias
+	SliceWithoutPtrs       []*StructWithoutPtrsAlias
+	MapWithPtrs            map[string]*StructWithPtrsAlias
+	MapWithoutPtrs         map[string]*StructWithoutPtrsAlias
+	MapOfSlicesWithPtrs    map[string][]*StructWithPtrsAlias
+	MapOfSlicesWithoutPtrs map[string][]*StructWithoutPtrsAlias
 }{})
 
 // Clone makes a deep copy of GenericTypeAliasStruct.

cmd/viewer/tests/tests_view.go

@@ -724,11 +724,60 @@ func (v *StructWithTypeAliasFieldsView) UnmarshalJSON(b []byte) error {
 
 func (v StructWithTypeAliasFieldsView) WithPtr() StructWithPtrsView        { return v.ж.WithPtr.View() }
 func (v StructWithTypeAliasFieldsView) WithoutPtr() StructWithoutPtrsAlias { return v.ж.WithoutPtr }
+func (v StructWithTypeAliasFieldsView) WithPtrByPtr() StructWithPtrsAliasView {
+	return v.ж.WithPtrByPtr.View()
+}
+func (v StructWithTypeAliasFieldsView) WithoutPtrByPtr() *StructWithoutPtrsAlias {
+	if v.ж.WithoutPtrByPtr == nil {
+		return nil
+	}
+	x := *v.ж.WithoutPtrByPtr
+	return &x
+}
+
+func (v StructWithTypeAliasFieldsView) SliceWithPtrs() views.SliceView[*StructWithPtrsAlias, StructWithPtrsAliasView] {
+	return views.SliceOfViews[*StructWithPtrsAlias, StructWithPtrsAliasView](v.ж.SliceWithPtrs)
+}
+func (v StructWithTypeAliasFieldsView) SliceWithoutPtrs() views.SliceView[*StructWithoutPtrsAlias, StructWithoutPtrsAliasView] {
+	return views.SliceOfViews[*StructWithoutPtrsAlias, StructWithoutPtrsAliasView](v.ж.SliceWithoutPtrs)
+}
+
+func (v StructWithTypeAliasFieldsView) MapWithPtrs() views.MapFn[string, *StructWithPtrsAlias, StructWithPtrsAliasView] {
+	return views.MapFnOf(v.ж.MapWithPtrs, func(t *StructWithPtrsAlias) StructWithPtrsAliasView {
+		return t.View()
+	})
+}
+
+func (v StructWithTypeAliasFieldsView) MapWithoutPtrs() views.MapFn[string, *StructWithoutPtrsAlias, StructWithoutPtrsAliasView] {
+	return views.MapFnOf(v.ж.MapWithoutPtrs, func(t *StructWithoutPtrsAlias) StructWithoutPtrsAliasView {
+		return t.View()
+	})
+}
+
+func (v StructWithTypeAliasFieldsView) MapOfSlicesWithPtrs() views.MapFn[string, []*StructWithPtrsAlias, views.SliceView[*StructWithPtrsAlias, StructWithPtrsAliasView]] {
+	return views.MapFnOf(v.ж.MapOfSlicesWithPtrs, func(t []*StructWithPtrsAlias) views.SliceView[*StructWithPtrsAlias, StructWithPtrsAliasView] {
+		return views.SliceOfViews[*StructWithPtrsAlias, StructWithPtrsAliasView](t)
+	})
+}
+
+func (v StructWithTypeAliasFieldsView) MapOfSlicesWithoutPtrs() views.MapFn[string, []*StructWithoutPtrsAlias, views.SliceView[*StructWithoutPtrsAlias, StructWithoutPtrsAliasView]] {
+	return views.MapFnOf(v.ж.MapOfSlicesWithoutPtrs, func(t []*StructWithoutPtrsAlias) views.SliceView[*StructWithoutPtrsAlias, StructWithoutPtrsAliasView] {
+		return views.SliceOfViews[*StructWithoutPtrsAlias, StructWithoutPtrsAliasView](t)
+	})
+}
 
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
 var _StructWithTypeAliasFieldsViewNeedsRegeneration = StructWithTypeAliasFields(struct {
 	WithPtr                StructWithPtrsAlias
 	WithoutPtr             StructWithoutPtrsAlias
+	WithPtrByPtr           *StructWithPtrsAlias
+	WithoutPtrByPtr        *StructWithoutPtrsAlias
+	SliceWithPtrs          []*StructWithPtrsAlias
+	SliceWithoutPtrs       []*StructWithoutPtrsAlias
+	MapWithPtrs            map[string]*StructWithPtrsAlias
+	MapWithoutPtrs         map[string]*StructWithoutPtrsAlias
+	MapOfSlicesWithPtrs    map[string][]*StructWithPtrsAlias
+	MapOfSlicesWithoutPtrs map[string][]*StructWithoutPtrsAlias
 }{})
 
 // View returns a readonly view of GenericTypeAliasStruct.

cmd/viewer/viewer.go

@@ -230,7 +230,7 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 				writeTemplate("sliceField")
 			}
 			continue
-		case *types.Struct, *types.Named:
+		case *types.Struct:
 			strucT := underlying
 			args.FieldType = it.QualifiedName(fieldType)
 			if codegen.ContainsPointers(strucT) {
@@ -262,7 +262,7 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 			mElem := m.Elem()
 			var template string
 			switch u := mElem.(type) {
-			case *types.Struct, *types.Named:
+			case *types.Struct, *types.Named, *types.Alias:
 				strucT := u
 				args.FieldType = it.QualifiedName(fieldType)
 				if codegen.ContainsPointers(strucT) {
@@ -281,7 +281,7 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 				slice := u
 				sElem := slice.Elem()
 				switch x := sElem.(type) {
-				case *types.Basic, *types.Named:
+				case *types.Basic, *types.Named, *types.Alias:
 					sElem := it.QualifiedName(sElem)
 					args.MapValueView = fmt.Sprintf("views.Slice[%v]", sElem)
 					args.MapValueType = sElem
@@ -292,7 +292,7 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 					template = "unsupportedField"
 					if _, isIface := pElem.Underlying().(*types.Interface); !isIface {
 						switch pElem.(type) {
-						case *types.Struct, *types.Named:
+						case *types.Struct, *types.Named, *types.Alias:
 							ptrType := it.QualifiedName(ptr)
 							viewType := appendNameSuffix(it.QualifiedName(pElem), "View")
 							args.MapFn = fmt.Sprintf("views.SliceOfViews[%v,%v](t)", ptrType, viewType)
@@ -313,7 +313,7 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 				pElem := ptr.Elem()
 				if _, isIface := pElem.Underlying().(*types.Interface); !isIface {
 					switch pElem.(type) {
-					case *types.Struct, *types.Named:
+					case *types.Struct, *types.Named, *types.Alias:
 						args.MapValueType = it.QualifiedName(ptr)
 						args.MapValueView = appendNameSuffix(it.QualifiedName(pElem), "View")
 						args.MapFn = "t.View()"
@@ -422,7 +422,7 @@ func viewTypeForValueType(typ types.Type) types.Type {
 func viewTypeForContainerType(typ types.Type) (*types.Named, *types.Func) {
 	// The container type should be an instantiated generic type,
 	// with its first type parameter specifying the element type.
-	containerType, ok := typ.(*types.Named)
+	containerType, ok := codegen.NamedTypeOf(typ)
 	if !ok || containerType.TypeArgs().Len() == 0 {
 		return nil, nil
 	}
@@ -435,7 +435,7 @@ func viewTypeForContainerType(typ types.Type) (*types.Named, *types.Func) {
 	if !ok {
 		return nil, nil
 	}
-	containerViewGenericType, ok := containerViewTypeObj.Type().(*types.Named)
+	containerViewGenericType, ok := codegen.NamedTypeOf(containerViewTypeObj.Type())
 	if !ok || containerViewGenericType.TypeParams().Len() != containerType.TypeArgs().Len()+1 {
 		return nil, nil
 	}
@@ -448,7 +448,7 @@ func viewTypeForContainerType(typ types.Type) (*types.Named, *types.Func) {
 	}
 	// ...and add the element view type.
 	// For that, we need to first determine the named elem type...
-	elemType, ok := baseType(containerType.TypeArgs().At(containerType.TypeArgs().Len() - 1)).(*types.Named)
+	elemType, ok := codegen.NamedTypeOf(baseType(containerType.TypeArgs().At(containerType.TypeArgs().Len() - 1)))
 	if !ok {
 		return nil, nil
 	}
@@ -473,7 +473,7 @@ func viewTypeForContainerType(typ types.Type) (*types.Named, *types.Func) {
 	}
 	// If elemType is an instantiated generic type, instantiate the elemViewType as well.
 	if elemTypeArgs := elemType.TypeArgs(); elemTypeArgs != nil {
-		elemViewType = must.Get(types.Instantiate(nil, elemViewType, collectTypes(elemTypeArgs), false)).(*types.Named)
+		elemViewType, _ = codegen.NamedTypeOf(must.Get(types.Instantiate(nil, elemViewType, collectTypes(elemTypeArgs), false)))
 	}
 	// And finally set the elemViewType as the last type argument.
 	containerViewTypeArgs[len(containerViewTypeArgs)-1] = elemViewType

util/codegen/codegen.go

@@ -382,3 +382,12 @@ func LookupMethod(t types.Type, name string) *types.Func {
 	}
 	return nil
 }
+
+// NamedTypeOf is like t.(*types.Named), but also works with type aliases.
+func NamedTypeOf(t types.Type) (named *types.Named, ok bool) {
+	if a, ok := t.(*types.Alias); ok {
+		return NamedTypeOf(types.Unalias(a))
+	}
+	named, ok = t.(*types.Named)
+	return
+}