Add validate.UpdateValue, deprecate the By* forms

This is the last place that calls semantic DeepEqual directly.

pkg/apis/core/v1/zz_generated.validations.go

@@ -985,7 +985,8 @@ func Validate_NodeSpec(
 			if e := validate.OptionalValue(ctx, op, fldPath, obj, oldObj).MarkAlpha().MarkShortCircuit(); len(e) != 0 {
 				earlyReturn = true
 			}
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoUnset, validate.NoModify).MarkAlpha().MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoUnset, validate.NoModify).MarkAlpha().MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}

staging/src/k8s.io/apimachinery/pkg/api/validate/update.go

@@ -42,8 +42,8 @@ const (
 	NoRemoveItem
 )
 
-// UpdateValueByCompare verifies update constraints for comparable value types.
-func UpdateValueByCompare[T comparable](_ context.Context, op operation.Operation, fldPath *field.Path, value, oldValue *T, constraints ...UpdateConstraint) field.ErrorList {
+// UpdateValue verifies update constraints for value types.
+func UpdateValue[T any](_ context.Context, op operation.Operation, fldPath *field.Path, value, oldValue *T, equiv MatchFunc[T], constraints ...UpdateConstraint) field.ErrorList {
 	// nil oldValue means no prior value to compare against (eg: a new item at +k8s:eachVal scope) -> no transition to check.
 	if op.Type != operation.Update || oldValue == nil {
 		return nil
@@ -51,22 +51,24 @@ func UpdateValueByCompare[T comparable](_ context.Context, op operation.Operatio
 
 	var errs field.ErrorList
 	var zero T
+	valueIsZero := equiv(*value, zero)
+	oldValueIsZero := equiv(*oldValue, zero)
 
 	for _, constraint := range constraints {
 		switch constraint {
 		case NoSet:
-			if *oldValue == zero && *value != zero {
+			if oldValueIsZero && !valueIsZero {
 				errs = append(errs, field.Invalid(fldPath, nil, "field cannot be set once created").WithOrigin("update"))
 			}
 		case NoUnset:
-			if *oldValue != zero && *value == zero {
+			if !oldValueIsZero && valueIsZero {
 				errs = append(errs, field.Invalid(fldPath, nil, "field cannot be cleared once set").WithOrigin("update"))
 			}
 		case NoModify:
 			// Rely on validation ratcheting to detect that the value has changed.
 			// This check only verifies that the field was set in both the old and
 			// new objects, confirming it was a modification, not a set/unset.
-			if *oldValue != zero && *value != zero {
+			if !oldValueIsZero && !valueIsZero {
 				errs = append(errs, field.Invalid(fldPath, nil, "field cannot be modified once set").WithOrigin("update"))
 			}
 		}
@@ -75,6 +77,13 @@ func UpdateValueByCompare[T comparable](_ context.Context, op operation.Operatio
 	return errs
 }
 
+// UpdateValueByCompare verifies update constraints for comparable value types.
+//
+// Deprecated: Use UpdateValue instead.
+func UpdateValueByCompare[T comparable](ctx context.Context, op operation.Operation, fldPath *field.Path, value, oldValue *T, constraints ...UpdateConstraint) field.ErrorList {
+	return UpdateValue(ctx, op, fldPath, value, oldValue, func(a, b T) bool { return a == b }, constraints...)
+}
+
 // UpdatePointer verifies update constraints for pointer types.
 func UpdatePointer[T any](_ context.Context, op operation.Operation, fldPath *field.Path, value, oldValue *T, constraints ...UpdateConstraint) field.ErrorList {
 	if op.Type != operation.Update {
@@ -107,38 +116,10 @@ func UpdatePointer[T any](_ context.Context, op operation.Operation, fldPath *fi
 }
 
 // UpdateValueByReflect verifies update constraints for non-comparable value types using reflection.
-func UpdateValueByReflect[T any](_ context.Context, op operation.Operation, fldPath *field.Path, value, oldValue *T, constraints ...UpdateConstraint) field.ErrorList {
-	// nil oldValue means no prior value to compare against (eg: a new item at +k8s:eachVal scope) -> no transition to check.
-	if op.Type != operation.Update || oldValue == nil {
-		return nil
-	}
-
-	var errs field.ErrorList
-	var zero T
-	valueIsZero := equality.Semantic.DeepEqual(*value, zero)
-	oldValueIsZero := equality.Semantic.DeepEqual(*oldValue, zero)
-
-	for _, constraint := range constraints {
-		switch constraint {
-		case NoSet:
-			if oldValueIsZero && !valueIsZero {
-				errs = append(errs, field.Invalid(fldPath, nil, "field cannot be set once created").WithOrigin("update"))
-			}
-		case NoUnset:
-			if !oldValueIsZero && valueIsZero {
-				errs = append(errs, field.Invalid(fldPath, nil, "field cannot be cleared once set").WithOrigin("update"))
-			}
-		case NoModify:
-			// Rely on validation ratcheting to detect that the value has changed.
-			// This check only verifies that the field was set in both the old and
-			// new objects, confirming it was a modification, not a set/unset.
-			if !oldValueIsZero && !valueIsZero {
-				errs = append(errs, field.Invalid(fldPath, nil, "field cannot be modified once set").WithOrigin("update"))
-			}
-		}
-	}
-
-	return errs
+//
+// Deprecated: Use UpdateValue instead.
+func UpdateValueByReflect[T any](ctx context.Context, op operation.Operation, fldPath *field.Path, value, oldValue *T, constraints ...UpdateConstraint) field.ErrorList {
+	return UpdateValue(ctx, op, fldPath, value, oldValue, func(a, b T) bool { return equality.Semantic.DeepEqual(a, b) }, constraints...)
 }
 
 // UpdateStruct verifies update constraints for non-pointer struct types.

staging/src/k8s.io/apimachinery/pkg/api/validate/update_test.go

@@ -138,10 +138,153 @@ func TestUpdateValue(t *testing.T) {
 		},
 	}
 
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			op := operation.Operation{Type: tt.op}
+			errs := UpdateValue(context.TODO(), op, field.NewPath("test"), &tt.value, &tt.oldValue, func(a, b string) bool { return a == b }, tt.constraints...)
+			if len(errs) != tt.wantErrs {
+				t.Errorf("UpdateValue() returned %d errors, want %d: %v", len(errs), tt.wantErrs, errs)
+			}
+			for i, msg := range tt.wantMsgs {
+				if i >= len(errs) {
+					t.Errorf("Expected error message %q not found", msg)
+					continue
+				}
+				if errs[i].Detail != msg {
+					t.Errorf("UpdateValue() error message = %q, want %q", errs[i].Detail, msg)
+				}
+			}
+		})
+	}
+}
+
+func TestUpdateValueByCompare(t *testing.T) {
+	tests := []struct {
+		name        string
+		op          operation.Type
+		value       string
+		oldValue    string
+		constraints []UpdateConstraint
+		wantErrs    int
+		wantMsgs    []string
+	}{
+		{
+			name:        "NoSet - unset to set transition (forbidden)",
+			op:          operation.Update,
+			value:       "value",
+			oldValue:    "",
+			constraints: []UpdateConstraint{NoSet},
+			wantErrs:    1,
+			wantMsgs:    []string{"field cannot be set once created"},
+		},
+		{
+			name:        "NoUnset - set to unset transition (forbidden)",
+			op:          operation.Update,
+			value:       "",
+			oldValue:    "value",
+			constraints: []UpdateConstraint{NoUnset},
+			wantErrs:    1,
+			wantMsgs:    []string{"field cannot be cleared once set"},
+		},
+		{
+			name:        "NoModify - set to different value (forbidden)",
+			op:          operation.Update,
+			value:       "value2",
+			oldValue:    "value1",
+			constraints: []UpdateConstraint{NoModify},
+			wantErrs:    1,
+			wantMsgs:    []string{"field cannot be modified once set"},
+		},
+	}
+
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			op := operation.Operation{Type: tt.op}
 			errs := UpdateValueByCompare(context.TODO(), op, field.NewPath("test"), &tt.value, &tt.oldValue, tt.constraints...)
+			if len(errs) != tt.wantErrs {
+				t.Errorf("UpdateValueByCompare() returned %d errors, want %d: %v", len(errs), tt.wantErrs, errs)
+			}
+			for i, msg := range tt.wantMsgs {
+				if i >= len(errs) {
+					t.Errorf("Expected error message %q not found", msg)
+					continue
+				}
+				if errs[i].Detail != msg {
+					t.Errorf("UpdateValueByCompare() error message = %q, want %q", errs[i].Detail, msg)
+				}
+			}
+		})
+	}
+}
+
+func TestUpdateValue_CustomMatchFunc(t *testing.T) {
+	type NonComparableStruct struct {
+		Name string
+		Tags []string
+	}
+
+	customEquiv := func(a, b NonComparableStruct) bool {
+		return a.Name == b.Name && (len(a.Tags) == 0 && len(b.Tags) == 0 || (len(a.Tags) == len(b.Tags) && a.Tags[0] == b.Tags[0]))
+	}
+
+	tests := []struct {
+		name        string
+		op          operation.Type
+		value       NonComparableStruct
+		oldValue    NonComparableStruct
+		constraints []UpdateConstraint
+		wantErrs    int
+		wantMsgs    []string
+	}{
+		{
+			name:        "NoSet - unset to set (forbidden)",
+			op:          operation.Update,
+			value:       NonComparableStruct{Name: "foo", Tags: []string{"a"}},
+			oldValue:    NonComparableStruct{},
+			constraints: []UpdateConstraint{NoSet},
+			wantErrs:    1,
+			wantMsgs:    []string{"field cannot be set once created"},
+		},
+		{
+			name:        "NoUnset - set to unset (forbidden)",
+			op:          operation.Update,
+			value:       NonComparableStruct{},
+			oldValue:    NonComparableStruct{Name: "foo", Tags: []string{"a"}},
+			constraints: []UpdateConstraint{NoUnset},
+			wantErrs:    1,
+			wantMsgs:    []string{"field cannot be cleared once set"},
+		},
+		{
+			name:        "NoModify - zero to non-zero transition (allowed)",
+			op:          operation.Update,
+			value:       NonComparableStruct{Name: "foo", Tags: []string{"a"}},
+			oldValue:    NonComparableStruct{},
+			constraints: []UpdateConstraint{NoModify},
+			wantErrs:    0,
+		},
+		{
+			name:        "NoModify - non-zero to zero transition (allowed)",
+			op:          operation.Update,
+			value:       NonComparableStruct{},
+			oldValue:    NonComparableStruct{Name: "foo", Tags: []string{"a"}},
+			constraints: []UpdateConstraint{NoModify},
+			wantErrs:    0,
+		},
+		{
+			name:        "NoModify - non-zero to non-zero transition (forbidden)",
+			op:          operation.Update,
+			value:       NonComparableStruct{Name: "foo", Tags: []string{"b"}},
+			oldValue:    NonComparableStruct{Name: "foo", Tags: []string{"a"}},
+			constraints: []UpdateConstraint{NoModify},
+			wantErrs:    1,
+			wantMsgs:    []string{"field cannot be modified once set"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			op := operation.Operation{Type: tt.op}
+			errs := UpdateValue(context.TODO(), op, field.NewPath("test"), &tt.value, &tt.oldValue, customEquiv, tt.constraints...)
 			if len(errs) != tt.wantErrs {
 				t.Errorf("UpdateValue() returned %d errors, want %d: %v", len(errs), tt.wantErrs, errs)
 			}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/levels/simple/zz_generated.validations.go

@@ -219,7 +219,8 @@ func Validate_SpecialValidationStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkAlpha().MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoModify).MarkAlpha().MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -248,7 +249,8 @@ func Validate_SpecialValidationStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkBeta().MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoModify).MarkBeta().MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/monotonic/zz_generated.validations.go

@@ -258,7 +258,8 @@ func Validate_Struct(
 			if e := validate.OptionalValue(ctx, op, fldPath, obj, oldObj).MarkShortCircuit(); len(e) != 0 {
 				earlyReturn = true
 			}
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoUnset).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a int, b int) bool { return a == b }, validate.NoUnset).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/options/update/zz_generated.validations.go

@@ -136,7 +136,8 @@ func Validate_Struct(
 			earlyReturn := false
 			if e := validate.IfOption(ctx, op, fldPath, obj, oldObj, "FeatureX", true,
 				func(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj *string) field.ErrorList {
-					return validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify)
+					return validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+						func(a string, b string) bool { return a == b }, validate.NoModify)
 				}).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
@@ -168,7 +169,8 @@ func Validate_Struct(
 			earlyReturn := false
 			if e := validate.IfOption(ctx, op, fldPath, obj, oldObj, "FeatureX", false,
 				func(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj *string) field.ErrorList {
-					return validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify)
+					return validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+						func(a string, b string) bool { return a == b }, validate.NoModify)
 				}).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/subfield/shortcircuit/zz_generated.validations.go

@@ -1029,7 +1029,8 @@ func Validate_ParentWithUpdate(
 				if e := validate.Subfield(ctx, op, fldPath, obj, oldObj, "value",
 					func(o *TargetWithUpdate) *string { return &o.Value }, validate.DirectEqual,
 					func(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj *string) field.ErrorList {
-						return validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify)
+						return validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+							func(a string, b string) bool { return a == b }, validate.NoModify)
 					}).MarkShortCircuit(); len(e) != 0 {
 					earlyReturn = true
 				}
@@ -1308,7 +1309,8 @@ func Validate_TargetWithUpdate(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/update/primitives/zz_generated.validations.go

@@ -77,7 +77,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoSet).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoSet).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -106,7 +107,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoUnset).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoUnset).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -135,7 +137,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -164,7 +167,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoSet, validate.NoUnset, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoSet, validate.NoUnset, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -193,7 +197,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoUnset, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a string, b string) bool { return a == b }, validate.NoUnset, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -222,7 +227,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a int, b int) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -251,7 +257,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a int32, b int32) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -280,7 +287,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a int64, b int64) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -309,7 +317,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a uint, b uint) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -338,7 +347,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a bool, b bool) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -367,7 +377,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a float32, b float32) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -396,7 +407,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a float64, b float64) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -425,7 +437,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a byte, b byte) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -715,7 +728,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a CustomString, b CustomString) bool { return a == b }, validate.NoModify).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}
@@ -744,7 +758,8 @@ func Validate_UpdateTestStruct(
 			}
 			// call field-attached validations
 			earlyReturn := false
-			if e := validate.UpdateValueByCompare(ctx, op, fldPath, obj, oldObj, validate.NoSet).MarkShortCircuit(); len(e) != 0 {
+			if e := validate.UpdateValue(ctx, op, fldPath, obj, oldObj,
+				func(a CustomInt, b CustomInt) bool { return a == b }, validate.NoSet).MarkShortCircuit(); len(e) != 0 {
 				errs = append(errs, e...)
 				earlyReturn = true
 			}

staging/src/k8s.io/code-generator/cmd/validation-gen/validators/update.go

@@ -199,13 +199,12 @@ func (utc updateTagCollector) Docs() TagDoc {
 }
 
 var (
-	updateValueValidator          = types.Name{Package: libValidationPkg, Name: "UpdateValueByCompare"}
-	updatePointerValidator        = types.Name{Package: libValidationPkg, Name: "UpdatePointer"}
-	updateValueByReflectValidator = types.Name{Package: libValidationPkg, Name: "UpdateValueByReflect"}
-	updateStructValidator         = types.Name{Package: libValidationPkg, Name: "UpdateStruct"}
-	valSliceUpdateValidator       = types.Name{Package: libValidationPkg, Name: "ValSliceUpdate"}
-	ptrSliceUpdateValidator       = types.Name{Package: libValidationPkg, Name: "PtrSliceUpdate"}
-	updateMapValidator            = types.Name{Package: libValidationPkg, Name: "UpdateMap"}
+	updateValueValidator    = types.Name{Package: libValidationPkg, Name: "UpdateValue"}
+	updatePointerValidator  = types.Name{Package: libValidationPkg, Name: "UpdatePointer"}
+	updateStructValidator   = types.Name{Package: libValidationPkg, Name: "UpdateStruct"}
+	valSliceUpdateValidator = types.Name{Package: libValidationPkg, Name: "ValSliceUpdate"}
+	ptrSliceUpdateValidator = types.Name{Package: libValidationPkg, Name: "PtrSliceUpdate"}
+	updateMapValidator      = types.Name{Package: libValidationPkg, Name: "UpdateMap"}
 
 	// Constraint constants that will be used as arguments
 	noSetConstraint        = types.Name{Package: libValidationPkg, Name: "NoSet"}
@@ -314,9 +313,8 @@ func generateMapValidation(constraints []validate.UpdateConstraint) Validations
 	return Validations{Functions: []FunctionGen{fn}}
 }
 
-// emitScalarUpdate emits a call to
-// UpdateValueByCompare/UpdatePointer/UpdateStruct/UpdateValueByReflect based
-// on the Go kind of context.Type.
+// emitScalarUpdate emits a call to UpdateValue/UpdatePointer/UpdateStruct
+// based on the Go kind of context.Type.
 // Used for both field scope (scalar/pointer/struct) and list/map element
 // scope via +k8s:eachVal.
 func emitScalarUpdate(context Context, constraints []validate.UpdateConstraint) Validations {
@@ -327,21 +325,33 @@ func emitScalarUpdate(context Context, constraints []validate.UpdateConstraint)
 	isComparable := util.IsDirectComparable(t)
 
 	var validatorFunc types.Name
+	var args []any
 	if isPointer {
 		validatorFunc = updatePointerValidator
+		args = constraintIdentifierArgs(constraints)
 	} else if isStruct {
 		validatorFunc = updateStructValidator
-	} else if isComparable {
-		validatorFunc = updateValueValidator
+		args = constraintIdentifierArgs(constraints)
 	} else {
-		validatorFunc = updateValueByReflectValidator
+		validatorFunc = updateValueValidator
+		var matchArg any
+		if isComparable {
+			matchArg = FunctionLiteral{
+				Parameters: []ParamResult{{"a", context.Type}, {"b", context.Type}},
+				Results:    []ParamResult{{"", types.Bool}},
+				Body:       "return a == b",
+			}
+		} else {
+			matchArg = Identifier(validateSemanticDeepEqual)
+		}
+		args = append([]any{matchArg}, constraintIdentifierArgs(constraints)...)
 	}
 
 	// Use ShortCircuit flag so these run in the same group as +k8s:optional.
 	// Scalar/pointer/struct fields only accept NoSet/NoUnset/NoModify
 	// (validateConstraintsForType rejects the rest), all of which emit
 	// field.Invalid at the field path.
-	fn := Function(updateTagName, ShortCircuit, validatorFunc, constraintIdentifierArgs(constraints)...).
+	fn := Function(updateTagName, ShortCircuit, validatorFunc, args...).
 		WithEmits(Emission{field.ErrorTypeInvalid, "update", ""})
 	return Validations{Functions: []FunctionGen{fn}}
 }