Move isExpressionDependentOnThis to ExpressionDependsOnThisHelper

Extract the static method into a standalone helper class to avoid
ConstantConditionRuleHelper depending on ImpossibleCheckTypeHelper.

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

Author: phpstan-bot

src/Rules/Comparison/ConstantConditionRuleHelper.php

@@ -64,7 +64,7 @@ private function shouldSkip(Scope $scope, Expr $expr): bool
 
 			if ($scope->isInTrait()) {
 				foreach ($expr->getArgs() as $arg) {
-					if (ImpossibleCheckTypeHelper::isExpressionDependentOnThis($arg->value)) {
+					if (ExpressionDependsOnThisHelper::isExpressionDependentOnThis($arg->value)) {
 						return true;
 					}
 				}

src/Rules/Comparison/ExpressionDependsOnThisHelper.php

@@ -0,0 +1,36 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Comparison;
+
+use PhpParser\Node\Expr;
+
+final class ExpressionDependsOnThisHelper
+{
+
+	public static function isExpressionDependentOnThis(Expr $expr): bool
+	{
+		if ($expr instanceof Expr\Variable && $expr->name === 'this') {
+			return true;
+		}
+
+		if ($expr instanceof Expr\PropertyFetch || $expr instanceof Expr\NullsafePropertyFetch) {
+			return self::isExpressionDependentOnThis($expr->var);
+		}
+
+		if ($expr instanceof Expr\MethodCall || $expr instanceof Expr\NullsafeMethodCall) {
+			return self::isExpressionDependentOnThis($expr->var);
+		}
+
+		if ($expr instanceof Expr\StaticPropertyFetch || $expr instanceof Expr\StaticCall) {
+			if ($expr->class instanceof Expr) {
+				return self::isExpressionDependentOnThis($expr->class);
+			}
+
+			$className = $expr->class->toString();
+			return in_array($className, ['self', 'static', 'parent'], true);
+		}
+
+		return false;
+	}
+
+}

src/Rules/Comparison/ImpossibleCheckTypeHelper.php

@@ -198,6 +198,10 @@ public function findSpecifiedType(
 					}
 				} elseif ($functionName === 'method_exists' && $argsCount >= 2) {
 					$objectArg = $args[0]->value;
+
+					if ($scope->isInTrait() && ExpressionDependsOnThisHelper::isExpressionDependentOnThis($objectArg)) {
+						return null;
+					}
 					$objectType = $this->treatPhpDocTypesAsCertain ? $scope->getType($objectArg) : $scope->getNativeType($objectArg);
 
 					if ($objectType instanceof ConstantStringType
@@ -310,7 +314,7 @@ public function findSpecifiedType(
 				continue;
 			}
 
-			if ($scope->isInTrait() && self::isExpressionDependentOnThis($sureType[0])) {
+			if ($scope->isInTrait() && ExpressionDependsOnThisHelper::isExpressionDependentOnThis($sureType[0])) {
 				$results[] = TrinaryLogic::createMaybe();
 				continue;
 			}
@@ -341,7 +345,7 @@ public function findSpecifiedType(
 				continue;
 			}
 
-			if ($scope->isInTrait() && self::isExpressionDependentOnThis($sureNotType[0])) {
+			if ($scope->isInTrait() && ExpressionDependsOnThisHelper::isExpressionDependentOnThis($sureNotType[0])) {
 				$results[] = TrinaryLogic::createMaybe();
 				continue;
 			}
@@ -391,32 +395,6 @@ private static function isSpecified(Scope $scope, Expr $node, Expr $expr): bool
 		) && $scope->hasExpressionType($expr)->yes();
 	}
 
-	public static function isExpressionDependentOnThis(Expr $expr): bool
-	{
-		if ($expr instanceof Expr\Variable && $expr->name === 'this') {
-			return true;
-		}
-
-		if ($expr instanceof Expr\PropertyFetch || $expr instanceof Expr\NullsafePropertyFetch) {
-			return self::isExpressionDependentOnThis($expr->var);
-		}
-
-		if ($expr instanceof Expr\MethodCall || $expr instanceof Expr\NullsafeMethodCall) {
-			return self::isExpressionDependentOnThis($expr->var);
-		}
-
-		if ($expr instanceof Expr\StaticPropertyFetch || $expr instanceof Expr\StaticCall) {
-			if ($expr->class instanceof Expr) {
-				return self::isExpressionDependentOnThis($expr->class);
-			}
-
-			$className = $expr->class->toString();
-			return in_array($className, ['self', 'static', 'parent'], true);
-		}
-
-		return false;
-	}
-
 	/**
 	 * @param Node\Arg[] $args
 	 */