encoding/xml: use reflect.TypeFor for known types

For #60088

Change-Id: Ib2589b994d304cca1f2e2081639959d80818ac7f
Reviewed-on: https://go-review.googlesource.com/c/go/+/514639
Run-TryBot: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>

Author: ianlancetaylor

src/encoding/xml/marshal.go

@@ -415,9 +415,9 @@ func (p *printer) popPrefix() {
 }
 
 var (
-	marshalerType     = reflect.TypeOf((*Marshaler)(nil)).Elem()
-	marshalerAttrType = reflect.TypeOf((*MarshalerAttr)(nil)).Elem()
-	textMarshalerType = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
+	marshalerType     = reflect.TypeFor[Marshaler]()
+	marshalerAttrType = reflect.TypeFor[MarshalerAttr]()
+	textMarshalerType = reflect.TypeFor[encoding.TextMarshaler]()
 )
 
 // marshalValue writes one or more XML elements representing val.

src/encoding/xml/read.go

@@ -304,10 +304,10 @@ func (d *Decoder) unmarshalAttr(val reflect.Value, attr Attr) error {
 }
 
 var (
-	attrType            = reflect.TypeOf(Attr{})
-	unmarshalerType     = reflect.TypeOf((*Unmarshaler)(nil)).Elem()
-	unmarshalerAttrType = reflect.TypeOf((*UnmarshalerAttr)(nil)).Elem()
-	textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+	attrType            = reflect.TypeFor[Attr]()
+	unmarshalerType     = reflect.TypeFor[Unmarshaler]()
+	unmarshalerAttrType = reflect.TypeFor[UnmarshalerAttr]()
+	textUnmarshalerType = reflect.TypeFor[encoding.TextUnmarshaler]()
 )
 
 const (

src/encoding/xml/read_test.go

@@ -326,10 +326,10 @@ type BadPathEmbeddedB struct {
 var badPathTests = []struct {
 	v, e any
 }{
-	{&BadPathTestA{}, &TagPathError{reflect.TypeOf(BadPathTestA{}), "First", "items>item1", "Second", "items"}},
-	{&BadPathTestB{}, &TagPathError{reflect.TypeOf(BadPathTestB{}), "First", "items>item1", "Second", "items>item1>value"}},
-	{&BadPathTestC{}, &TagPathError{reflect.TypeOf(BadPathTestC{}), "First", "", "Second", "First"}},
-	{&BadPathTestD{}, &TagPathError{reflect.TypeOf(BadPathTestD{}), "First", "", "Second", "First"}},
+	{&BadPathTestA{}, &TagPathError{reflect.TypeFor[BadPathTestA](), "First", "items>item1", "Second", "items"}},
+	{&BadPathTestB{}, &TagPathError{reflect.TypeFor[BadPathTestB](), "First", "items>item1", "Second", "items>item1>value"}},
+	{&BadPathTestC{}, &TagPathError{reflect.TypeFor[BadPathTestC](), "First", "", "Second", "First"}},
+	{&BadPathTestD{}, &TagPathError{reflect.TypeFor[BadPathTestD](), "First", "", "Second", "First"}},
 }
 
 func TestUnmarshalBadPaths(t *testing.T) {

src/encoding/xml/typeinfo.go

@@ -46,7 +46,7 @@ const (
 
 var tinfoMap sync.Map // map[reflect.Type]*typeInfo
 
-var nameType = reflect.TypeOf(Name{})
+var nameType = reflect.TypeFor[Name]()
 
 // getTypeInfo returns the typeInfo structure with details necessary
 // for marshaling and unmarshaling typ.