switch tag Get("json") to Lookup("json")

pkg/api/testing/serialization_proto_test.go

@@ -88,7 +88,8 @@ func fieldsHaveProtobufTags(obj reflect.Type) error {
 				// TypeMeta is not included in external protobuf because we use an envelope type with TypeMeta
 				continue
 			}
-			if len(f.Tag.Get("json")) > 0 && len(f.Tag.Get("protobuf")) == 0 {
+			_, jsonTagExists := f.Tag.Lookup("json")
+			if jsonTagExists && len(f.Tag.Get("protobuf")) == 0 {
 				return fmt.Errorf("field %s in %s has a 'json' tag but no protobuf tag", f.Name, obj)
 			}
 		}

staging/src/k8s.io/apimachinery/pkg/api/apitesting/naming/naming.go

@@ -88,9 +88,9 @@ func ensureNoTags(gvk schema.GroupVersionKind, tp reflect.Type, parents []reflec
 			if f.PkgPath != "" {
 				continue // Ignore unexported fields
 			}
-			jsonTag := f.Tag.Get("json")
+			_, jsonTagExists := f.Tag.Lookup("json")
 			protoTag := f.Tag.Get("protobuf")
-			if len(jsonTag) > 0 || len(protoTag) > 0 {
+			if jsonTagExists || len(protoTag) > 0 {
 				errs = append(errs, fmt.Errorf("internal types should not have json or protobuf tags. %#v has tag on field %v: %v.\n%s", gvk, f.Name, f.Tag, fmtParentString(parents)))
 			}
 
@@ -126,9 +126,13 @@ func ensureTags(gvk schema.GroupVersionKind, tp reflect.Type, parents []reflect.
 	case reflect.Struct:
 		for i := 0; i < tp.NumField(); i++ {
 			f := tp.Field(i)
-			jsonTag := f.Tag.Get("json")
+			jsonTag, jsonTagExists := f.Tag.Lookup("json")
 			if len(jsonTag) == 0 {
-				errs = append(errs, fmt.Errorf("external types should have json tags. %#v tags on field %v are: %s.\n%s", gvk, f.Name, f.Tag, fmtParentString(parents)))
+				if f.Anonymous && jsonTagExists {
+					// allow json:"" on embedded fields
+				} else {
+					errs = append(errs, fmt.Errorf("external types should have json tags. %#v tags on field %v are: %s.\n%s", gvk, f.Name, f.Tag, fmtParentString(parents)))
+				}
 			}
 
 			jsonTagName := strings.Split(jsonTag, ",")[0]

staging/src/k8s.io/apimachinery/pkg/api/apitesting/roundtrip/construct.go

@@ -136,7 +136,8 @@ func fill(dataString string, dataInt int, t reflect.Type, v reflect.Value, fillF
 			}
 
 			// use the json field name, which must be stable
-			dataString := strings.Split(field.Tag.Get("json"), ",")[0]
+			jsonTag, _ := field.Tag.Lookup("json")
+			dataString = strings.Split(jsonTag, ",")[0]
 			if dataString == "-" {
 				// unserialized field, no need to fill it
 				continue

staging/src/k8s.io/apimachinery/pkg/conversion/queryparams/convert.go

@@ -34,8 +34,8 @@ type Unmarshaler interface {
 }
 
 func jsonTag(field reflect.StructField) (string, bool) {
-	structTag := field.Tag.Get("json")
-	if len(structTag) == 0 {
+	structTag, exists := field.Tag.Lookup("json")
+	if !exists || len(structTag) == 0 {
 		return "", false
 	}
 	parts := strings.Split(structTag, ",")

staging/src/k8s.io/apimachinery/pkg/runtime/conversion.go

@@ -20,7 +20,6 @@ package runtime
 
 import (
 	"fmt"
-	"reflect"
 	"strconv"
 	"strings"
 
@@ -41,18 +40,6 @@ func DefaultMetaV1FieldSelectorConversion(label, value string) (string, string,
 	}
 }
 
-// JSONKeyMapper uses the struct tags on a conversion to determine the key value for
-// the other side. Use when mapping from a map[string]* to a struct or vice versa.
-func JSONKeyMapper(key string, sourceTag, destTag reflect.StructTag) (string, string) {
-	if s := destTag.Get("json"); len(s) > 0 {
-		return strings.SplitN(s, ",", 2)[0], key
-	}
-	if s := sourceTag.Get("json"); len(s) > 0 {
-		return key, strings.SplitN(s, ",", 2)[0]
-	}
-	return key, key
-}
-
 func Convert_Slice_string_To_string(in *[]string, out *string, s conversion.Scope) error {
 	if len(*in) == 0 {
 		*out = ""

staging/src/k8s.io/apimachinery/pkg/runtime/converter.go

@@ -376,8 +376,8 @@ func fieldInfoFromField(structType reflect.Type, field int) *fieldInfo {
 	// Cache miss - we need to compute the field name.
 	info := &fieldInfo{}
 	typeField := structType.Field(field)
-	jsonTag := typeField.Tag.Get("json")
-	if len(jsonTag) == 0 {
+	jsonTag, exists := typeField.Tag.Lookup("json")
+	if !exists || len(jsonTag) == 0 {
 		if !typeField.Anonymous {
 			// match stdlib behavior for naming fields that don't specify a json tag name
 			info.name = typeField.Name

staging/src/k8s.io/apiserver/pkg/endpoints/installer.go

@@ -30,6 +30,7 @@ import (
 
 	"golang.org/x/text/cases"
 	"golang.org/x/text/language"
+
 	apidiscoveryv2 "k8s.io/api/apidiscovery/v2"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/conversion"
@@ -1177,7 +1178,7 @@ func AddObjectParams(ws *restful.WebService, route *restful.RouteBuilder, obj in
 				}
 				fallthrough
 			default:
-				jsonTag := sf.Tag.Get("json")
+				jsonTag, _ := sf.Tag.Lookup("json")
 				if len(jsonTag) == 0 {
 					continue
 				}

staging/src/k8s.io/client-go/util/jsonpath/jsonpath.go

@@ -361,7 +361,7 @@ func (j *JSONPath) findFieldInValue(value *reflect.Value, node *FieldNode) (refl
 	var inlineValue *reflect.Value
 	for ix := 0; ix < t.NumField(); ix++ {
 		f := t.Field(ix)
-		jsonTag := f.Tag.Get("json")
+		jsonTag, _ := f.Tag.Lookup("json")
 		parts := strings.Split(jsonTag, ",")
 		if len(parts) == 0 {
 			continue
@@ -369,7 +369,7 @@ func (j *JSONPath) findFieldInValue(value *reflect.Value, node *FieldNode) (refl
 		if parts[0] == node.Value {
 			return value.Field(ix), nil
 		}
-		if len(parts[0]) == 0 {
+		if len(parts[0]) == 0 && f.Anonymous {
 			val := value.Field(ix)
 			inlineValue = &val
 		}

staging/src/k8s.io/code-generator/cmd/go-to-protobuf/protobuf/generator.go

@@ -652,7 +652,7 @@ func membersToFields(locator ProtobufLocator, t *types.Type, localPackage types.
 		}
 
 		// extract information from JSON field tag
-		if tag := tags.Get("json"); len(tag) > 0 {
+		if tag, _ := tags.Lookup("json"); len(tag) > 0 {
 			parts := strings.Split(tag, ",")
 			if len(field.Name) == 0 && len(parts[0]) != 0 {
 				field.Name = parts[0]