refactor: restore go1.20 compatibility by dropping reflect.TypeFor

jsonpointer/resolve.go

@@ -33,7 +33,7 @@ func findByLabel(base reflect.Value, jsonLabel string) (reflect.Value, bool) {
 		return reflect.Value{}, false
 	}
 
-	for base.Kind() == reflect.Ptr || base.Kind() == reflect.Interface {
+	for base.Kind() == reflect.Pointer || base.Kind() == reflect.Interface {
 		if base.IsNil() {
 			return reflect.Value{}, false
 		}

reference.go

@@ -10,14 +10,14 @@ import (
 	"golang.org/x/exp/slices"
 )
 
-// NewReference creates a new reference to a field of a Object.
+// NewReference creates a new reference to a field of an Object.
 // The base must be a pointer to a struct implementing Object.
 // The field must be a pointer to a field within the base.
 func NewReference(base Object, field any) *Reference {
-	if reflect.ValueOf(base).Kind() != reflect.Ptr {
+	if reflect.ValueOf(base).Kind() != reflect.Pointer {
 		panic("Base must be a pointer to a struct implementing Object")
 	}
-	if reflect.ValueOf(field).Kind() != reflect.Ptr {
+	if reflect.ValueOf(field).Kind() != reflect.Pointer {
 		panic("field must be a pointer to a field within base")
 	}
 	return &Reference{
@@ -26,9 +26,9 @@ func NewReference(base Object, field any) *Reference {
 	}
 }
 
-// Reference is a reference to a field of a Object
+// Reference is a reference to a field of an Object
 type Reference struct {
-	Base         any // Must be a pointer to a Object
+	Base         any // Must be a pointer to an Object
 	PointedField any // Must be a pointer to a (possibly nested) field of Base
 
 	textLabel   string
@@ -42,7 +42,7 @@ func (r *Reference) ToJsonPointer() jsonpointer.Pointer {
 	}
 	baseValue := reflect.ValueOf(r.Base)
 	pointedValue := reflect.ValueOf(r.PointedField)
-	if pointedValue.Kind() != reflect.Ptr {
+	if pointedValue.Kind() != reflect.Pointer {
 		panic("PointedField must be a pointer")
 	}
 	r.jsonPointer = findRelativeJsonPointer(baseValue, pointedValue)
@@ -52,8 +52,12 @@ func (r *Reference) ToJsonPointer() jsonpointer.Pointer {
 	return r.jsonPointer
 }
 
-var referenceType = reflect.TypeFor[Reference]()
+var referenceType = reflect.TypeOf((*Reference)(nil)).Elem()
 
+// findRelativeJsonPointer finds a JSON pointer from base to pointedField. The
+// base must be pointer. The pointed field should be a pointer to a field
+// within the base; if the pointed field is not found within the base, nil is
+// returned.
 func findRelativeJsonPointer(base reflect.Value, pointedField reflect.Value) jsonpointer.Pointer {
 	for {
 		if base.Equal(pointedField) {
@@ -65,7 +69,7 @@ func findRelativeJsonPointer(base reflect.Value, pointedField reflect.Value) jso
 		if base.Type() == referenceType { // Don't recurse into other references
 			return nil
 		}
-		if base.Kind() == reflect.Ptr || base.Kind() == reflect.Interface {
+		if base.Kind() == reflect.Pointer || base.Kind() == reflect.Interface {
 			if base.IsNil() {
 				return nil
 			}
@@ -123,7 +127,7 @@ func (r *Reference) ToTextLabel() string {
 	}
 	baseValue := reflect.ValueOf(r.Base).Elem()
 	pointedValue := reflect.ValueOf(r.PointedField)
-	if pointedValue.Kind() != reflect.Ptr {
+	if pointedValue.Kind() != reflect.Pointer {
 		panic("PointedField must be a pointer")
 	}
 	r.textLabel, _ = findTextLabel(baseValue, reflect.ValueOf(r.PointedField))
@@ -143,7 +147,7 @@ func findTextLabel(base reflect.Value, pointedField reflect.Value) (string, bool
 	if base.Addr().Equal(pointedField) {
 		return "", true
 	}
-	if base.Kind() == reflect.Ptr || base.Kind() == reflect.Interface {
+	if base.Kind() == reflect.Pointer || base.Kind() == reflect.Interface {
 		base = base.Elem()
 	}
 	if base.Kind() != reflect.Struct {
@@ -156,7 +160,7 @@ func findTextLabel(base reflect.Value, pointedField reflect.Value) (string, bool
 			continue
 		}
 		var fieldPointer = field
-		if field.Kind() != reflect.Ptr {
+		if field.Kind() != reflect.Pointer {
 			fieldPointer = field.Addr()
 		}
 		var label string

reference_test.go

@@ -111,6 +111,8 @@ func TestReference_ToJsonPointer(t *testing.T) {
 		{&test.Valuer.Subfield7, "/valuer/subfield7"},
 		{&test.SubObject, "/subobject"},
 		{&test.SubObject.Subfield8, "/subobject/subfield8"},
+		// test.Recursive not required here: if there is a flaw in the pointer
+		// search logic, it will panic when encountering this cycle.
 	}
 	for _, tt := range tests {
 		t.Run(tt.want, func(t *testing.T) {

textlog.go

@@ -86,7 +86,7 @@ func withUppercaseKeys(entry TextlogEntry) TextlogEntry {
 }
 
 func (t TextlogFormatter) toEntry(object reflect.Value) TextlogEntry {
-	for object.Kind() == reflect.Ptr || object.Kind() == reflect.Interface {
+	for object.Kind() == reflect.Pointer || object.Kind() == reflect.Interface {
 		if object.IsNil() {
 			return nil
 		}
@@ -138,7 +138,7 @@ func (t TextlogFormatter) toEntry(object reflect.Value) TextlogEntry {
 			} else {
 				// Add the field as a single value
 				key := logfield
-				if field.Kind() == reflect.Ptr {
+				if field.Kind() == reflect.Pointer {
 					field = field.Elem()
 				}
 				details = append(details, TextlogValuePair{