refactor: rename TransitionRule to UsesOldSelf

not all rules that use OldSelf are transition rules, and this flag was used to check for oldSelf usage anyway, not specifically whether the rule was a transition rule

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go

@@ -1182,7 +1182,7 @@ func ValidateCustomResourceDefinitionOpenAPISchema(schema *apiextensions.JSONSch
 								}
 							}
 						}
-						if cr.TransitionRule {
+						if cr.UsesOldSelf {
 							if uncorrelatablePath := ssv.forbidOldSelfValidations(); uncorrelatablePath != nil {
 								allErrs.CELErrors = append(allErrs.CELErrors, field.Invalid(fldPath.Child("x-kubernetes-validations").Index(i).Child("rule"), schema.XValidations[i].Rule, fmt.Sprintf("oldSelf cannot be used on the uncorrelatable portion of the schema within %v", uncorrelatablePath)))
 							}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/compilation.go

@@ -48,9 +48,8 @@ const (
 type CompilationResult struct {
 	Program cel.Program
 	Error   *apiservercel.Error
-	// If true, the compiled expression contains a reference to the identifier "oldSelf", and its corresponding rule
-	// is implicitly a transition rule.
-	TransitionRule bool
+	// If true, the compiled expression contains a reference to the identifier "oldSelf".
+	UsesOldSelf bool
 	// Represents the worst-case cost of the compiled expression in terms of CEL's cost units, as used by cel.EstimateCost.
 	MaxCost uint64
 	// MaxCardinality represents the worse case number of times this validation rule could be invoked if contained under an
@@ -190,7 +189,7 @@ func compileRule(s *schema.Structural, rule apiextensions.ValidationRule, envSet
 	}
 	for _, ref := range checkedExpr.ReferenceMap {
 		if ref.Name == OldScopedVarName {
-			compilationResult.TransitionRule = true
+			compilationResult.UsesOldSelf = true
 			break
 		}
 	}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/compilation_test.go

@@ -140,7 +140,7 @@ func transitionRule(t bool) validationMatcher {
 }
 
 func (v transitionRuleMatcher) matches(cr CompilationResult) bool {
-	return cr.TransitionRule == bool(v)
+	return cr.UsesOldSelf == bool(v)
 }
 
 func (v transitionRuleMatcher) String() string {

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/validation.go

@@ -124,7 +124,7 @@ func validator(s *schema.Structural, isResourceRoot bool, declType *cel.DeclType
 	if len(compiledRules) > 0 || err != nil || itemsValidator != nil || additionalPropertiesValidator != nil || len(propertiesValidators) > 0 {
 		var activationFactory func(*schema.Structural, interface{}, interface{}) interpreter.Activation = validationActivationWithoutOldSelf
 		for _, rule := range compiledRules {
-			if rule.TransitionRule {
+			if rule.UsesOldSelf {
 				activationFactory = validationActivationWithOldSelf
 				break
 			}
@@ -300,7 +300,7 @@ func (s *Validator) validateExpressions(ctx context.Context, fldPath *field.Path
 			// rule is empty
 			continue
 		}
-		if compiled.TransitionRule && oldObj == nil {
+		if compiled.UsesOldSelf && oldObj == nil {
 			// transition rules are evaluated only if there is a comparable existing value
 			continue
 		}
@@ -344,7 +344,7 @@ func (s *Validator) validateExpressions(ctx context.Context, fldPath *field.Path
 			}
 
 			addErr := func(e *field.Error) {
-				if !compiled.TransitionRule && correlation.shouldRatchetError() {
+				if !compiled.UsesOldSelf && correlation.shouldRatchetError() {
 					warning.AddWarning(ctx, "", e.Error())
 				} else {
 					errs = append(errs, e)