Fix lint errors and skip testBug7599 on PHP < 8.1

- Use early exit in ConstantConditionRuleHelper to reduce nesting (SlevomatCodingStandard.ControlStructures.EarlyExit)
- Use \in_array() instead of fallback global name in ExpressionDependsOnThisHelper (SlevomatCodingStandard.Namespaces.ReferenceUsedNamesOnly)
- Skip testBug7599 on PHP < 8.1 using #[RequiresPhp] attribute (enums require PHP 8.1)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Rules/Comparison/ConstantConditionRuleHelper.php

@@ -62,20 +62,24 @@ private function shouldSkip(Scope $scope, Expr $expr): bool
 				return true;
 			}
 
-			if ($scope->isInTrait()) {
-				foreach ($expr->getArgs() as $arg) {
-					if (ExpressionDependsOnThisHelper::isExpressionDependentOnThis($arg->value)) {
-						return true;
-					}
+			if (!$scope->isInTrait()) {
+				return false;
+			}
+
+			foreach ($expr->getArgs() as $arg) {
+				if (ExpressionDependsOnThisHelper::isExpressionDependentOnThis($arg->value)) {
+					return true;
+				}
+
+				$classReflection = $scope->getClassReflection();
+				if ($classReflection === null) {
+					continue;
+				}
 
-					$classReflection = $scope->getClassReflection();
-					if ($classReflection !== null) {
-						$argType = $this->treatPhpDocTypesAsCertain ? $scope->getType($arg->value) : $scope->getNativeType($arg->value);
-						foreach ($argType->getObjectClassNames() as $className) {
-							if ($className === $classReflection->getName()) {
-								return true;
-							}
-						}
+				$argType = $this->treatPhpDocTypesAsCertain ? $scope->getType($arg->value) : $scope->getNativeType($arg->value);
+				foreach ($argType->getObjectClassNames() as $className) {
+					if ($className === $classReflection->getName()) {
+						return true;
 					}
 				}
 			}

src/Rules/Comparison/ExpressionDependsOnThisHelper.php

@@ -27,7 +27,7 @@ public static function isExpressionDependentOnThis(Expr $expr): bool
 			}
 
 			$className = $expr->class->toString();
-			return in_array($className, ['self', 'static', 'parent'], true);
+			return \in_array($className, ['self', 'static', 'parent'], true);
 		}
 
 		return false;

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -1205,6 +1205,7 @@ public function testBug13023(): void
 		$this->analyse([__DIR__ . '/data/bug-13023.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.1')]
 	public function testBug7599(): void
 	{
 		$this->treatPhpDocTypesAsCertain = true;