Support omitzero tags in optionalfields linter

Author: Karthik-K-N

pkg/analysis/helpers/extractjsontags/analyzer.go

@@ -29,6 +29,11 @@ import (
 	kalerrors "sigs.k8s.io/kube-api-linter/pkg/analysis/errors"
 )
 
+const (
+	omitEmpty = "omitempty"
+	omitZero  = "omitzero"
+)
+
 // StructFieldTags is used to find information about
 // json tags on fields within struct.
 type StructFieldTags interface {
@@ -140,10 +145,12 @@ func extractTagInfo(tag *ast.BasicLit) FieldTagInfo {
 
 	return FieldTagInfo{
 		Name:      tagName,
-		OmitEmpty: len(tagValues) == 2 && tagValues[1] == "omitempty",
-		RawValue:  tagValue,
-		Pos:       pos,
-		End:       end,
+		OmitEmpty: (len(tagValues) == 2 && tagValues[1] == omitEmpty) || (len(tagValues) == 3 && (tagValues[1] == omitEmpty || tagValues[2] == omitEmpty)),
+		// Considering, omitzero will always coexist with omitemtpy and it can be either second or third tag.
+		OmitZero: len(tagValues) == 3 && (tagValues[1] == omitZero || tagValues[2] == omitZero),
+		RawValue: tagValue,
+		Pos:      pos,
+		End:      end,
 	}
 }
 
@@ -159,6 +166,9 @@ type FieldTagInfo struct {
 	// OmitEmpty is true if the field has the omitempty option in the json tag.
 	OmitEmpty bool
 
+	// OmitZero is true if the field has the omitzero option in the json tag.
+	OmitZero bool
+
 	// Inline is true if the field has the inline option in the json tag.
 	Inline bool
 

pkg/analysis/optionalfields/analyzer.go

@@ -134,6 +134,7 @@ func defaultConfig(cfg *config.OptionalFieldsConfig) {
 func (a *analyzer) checkFieldProperties(pass *analysis.Pass, field *ast.Field, fieldName string, markersAccess markershelper.Markers, jsonTags extractjsontags.FieldTagInfo) {
 	hasValidZeroValue, completeValidation := isZeroValueValid(pass, field, field.Type, markersAccess)
 	hasOmitEmpty := jsonTags.OmitEmpty
+	hasOmitZero := jsonTags.OmitZero
 	isPointer, underlying := isStarExpr(field.Type)
 	isStruct := isStructType(pass, field.Type)
 
@@ -149,18 +150,21 @@ func (a *analyzer) checkFieldProperties(pass *analysis.Pass, field *ast.Field, f
 
 	if a.omitEmptyPolicy != config.OptionalFieldsOmitEmptyPolicyIgnore || hasOmitEmpty {
 		// If we require omitempty, or the field has omitempty, we can check the field properties based on it being an omitempty field.
-		a.checkFieldPropertiesWithOmitEmptyRequired(pass, field, fieldName, jsonTags, underlying, hasOmitEmpty, hasValidZeroValue, completeValidation, isPointer, isStruct)
+		a.checkFieldPropertiesWithOmitEmptyRequired(pass, field, fieldName, jsonTags, underlying, hasOmitEmpty, hasOmitZero, hasValidZeroValue, completeValidation, isPointer, isStruct)
 	} else {
 		// The field does not have omitempty, and does not require it.
 		a.checkFieldPropertiesWithoutOmitEmpty(pass, field, fieldName, jsonTags, underlying, hasValidZeroValue, completeValidation, isPointer, isStruct)
 	}
 }
 
-func (a *analyzer) checkFieldPropertiesWithOmitEmptyRequired(pass *analysis.Pass, field *ast.Field, fieldName string, jsonTags extractjsontags.FieldTagInfo, underlying ast.Expr, hasOmitEmpty, hasValidZeroValue, completeValidation, isPointer, isStruct bool) {
+func (a *analyzer) checkFieldPropertiesWithOmitEmptyRequired(pass *analysis.Pass, field *ast.Field, fieldName string, jsonTags extractjsontags.FieldTagInfo, underlying ast.Expr, hasOmitEmpty, hasOmitZero, hasValidZeroValue, completeValidation, isPointer, isStruct bool) {
 	// In this case, we should always add the omitempty if it isn't present.
 	a.handleFieldShouldHaveOmitEmpty(pass, field, fieldName, hasOmitEmpty, jsonTags)
 
 	switch {
+	case !hasValidZeroValue && isStruct && hasOmitZero:
+		// The struct field need not be pointer if it does not have valid zero value and has omitzero tag.
+		return
 	case hasValidZeroValue && !completeValidation:
 		a.handleIncompleteFieldValidation(pass, field, fieldName, isPointer, underlying)
 		fallthrough // Since it's a valid zero value, we should still enforce the pointer.
@@ -187,7 +191,7 @@ func (a *analyzer) checkFieldPropertiesWithoutOmitEmpty(pass *analysis.Pass, fie
 		// Once it has the omitempty tag, it will also need to be a pointer in some cases.
 		// Now handle it as if it had the omitempty already.
 		// We already handle the omitempty tag above, so force the `hasOmitEmpty` to true.
-		a.checkFieldPropertiesWithOmitEmptyRequired(pass, field, fieldName, jsonTags, underlying, true, hasValidZeroValue, completeValidation, isPointer, isStruct)
+		a.checkFieldPropertiesWithOmitEmptyRequired(pass, field, fieldName, jsonTags, underlying, true, false, hasValidZeroValue, completeValidation, isPointer, isStruct)
 	}
 }
 
@@ -300,7 +304,7 @@ func getStructZeroValue(pass *analysis.Pass, structType *ast.StructType) string
 	for _, field := range structType.Fields.List {
 		fieldTagInfo := jsonTagInfo.FieldTags(field)
 
-		if fieldTagInfo.OmitEmpty {
+		if fieldTagInfo.OmitEmpty || fieldTagInfo.OmitZero {
 			// If the field is omitted, we can use a zero value.
 			// For structs, if they aren't a pointer another error will be raised.
 			continue

pkg/analysis/optionalfields/testdata/src/b/a.go

@@ -171,6 +171,11 @@ type A struct {
 	// +optional
 	StructWithMinProperties B `json:"structWithMinProperties,omitempty"` // want "field StructWithMinProperties is optional and should be a pointer"
 
+	// StructWithMinPropertiesAndOmitEmptyTag is a struct field with a minimum number of properties.
+	// +kubebuilder:validation:MinProperties=1
+	// +optional
+	StructWithMinPropertiesAndOmitEmptyTag B `json:"structWithMinPropertiesAndOmitEmptyTag,omitempty,omitzero"`
+
 	// structWithMinPropertiesOnStruct is a struct field with a minimum number of properties on the struct.
 	// +optional
 	StructWithMinPropertiesOnStruct D `json:"structWithMinPropertiesOnStruct,omitempty"` // want "field StructWithMinPropertiesOnStruct is optional and should be a pointer"

pkg/analysis/optionalfields/testdata/src/b/a.go.golden

@@ -171,6 +171,11 @@ type A struct {
 	// +optional
 	StructWithMinProperties *B `json:"structWithMinProperties,omitempty"` // want "field StructWithMinProperties is optional and should be a pointer"
 
+	// StructWithMinPropertiesAndOmitEmptyTag is a struct field with a minimum number of properties.
+	// +kubebuilder:validation:MinProperties=1
+	// +optional
+	StructWithMinPropertiesAndOmitEmptyTag B `json:"structWithMinPropertiesAndOmitEmptyTag,omitempty,omitzero"`
+
 	// structWithMinPropertiesOnStruct is a struct field with a minimum number of properties on the struct.
 	// +optional
 	StructWithMinPropertiesOnStruct *D `json:"structWithMinPropertiesOnStruct,omitempty"` // want "field StructWithMinPropertiesOnStruct is optional and should be a pointer"

pkg/analysis/optionalfields/util.go

@@ -224,7 +224,7 @@ func areStructFieldZeroValuesValid(pass *analysis.Pass, structType *ast.StructTy
 	for _, field := range structType.Fields.List {
 		fieldTagInfo := jsonTagInfo.FieldTags(field)
 
-		if fieldTagInfo.OmitEmpty {
+		if fieldTagInfo.OmitEmpty || fieldTagInfo.OmitZero {
 			// If the field is omitted, we can use a zero value.
 			// For structs, if they aren't a pointer another error will be raised.
 			continue