Generalize trait $this check to cover property fetches and method calls

The previous fix only handled `$this` directly in trait context, but
similar false positives occur with expressions like `$this->foo` when
different classes using the trait define properties with different types.

Introduced `isExpressionDependentOnThis()` helper that recursively checks
if an expression is rooted in `$this`, covering Variable, PropertyFetch,
and MethodCall nodes.

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

Author: phpstan-bot

src/Rules/Comparison/ImpossibleCheckTypeHelper.php

@@ -310,7 +310,7 @@ public function findSpecifiedType(
 				continue;
 			}
 
-			if ($scope->isInTrait() && $sureType[0] instanceof Expr\Variable && $sureType[0]->name === 'this') {
+			if ($scope->isInTrait() && self::isExpressionDependentOnThis($sureType[0])) {
 				$results[] = TrinaryLogic::createMaybe();
 				continue;
 			}
@@ -341,7 +341,7 @@ public function findSpecifiedType(
 				continue;
 			}
 
-			if ($scope->isInTrait() && $sureNotType[0] instanceof Expr\Variable && $sureNotType[0]->name === 'this') {
+			if ($scope->isInTrait() && self::isExpressionDependentOnThis($sureNotType[0])) {
 				$results[] = TrinaryLogic::createMaybe();
 				continue;
 			}
@@ -391,6 +391,23 @@ private static function isSpecified(Scope $scope, Expr $node, Expr $expr): bool
 		) && $scope->hasExpressionType($expr)->yes();
 	}
 
+	private static function isExpressionDependentOnThis(Expr $expr): bool
+	{
+		if ($expr instanceof Expr\Variable && $expr->name === 'this') {
+			return true;
+		}
+
+		if ($expr instanceof Expr\PropertyFetch) {
+			return self::isExpressionDependentOnThis($expr->var);
+		}
+
+		if ($expr instanceof Expr\MethodCall) {
+			return self::isExpressionDependentOnThis($expr->var);
+		}
+
+		return false;
+	}
+
 	/**
 	 * @param Node\Arg[] $args
 	 */

tests/PHPStan/Rules/Comparison/data/bug-13023.php

@@ -23,3 +23,30 @@ public function getRandom(): int
 		return $value;
 	}
 }
+
+class SomeClass3
+{
+	use MyTrait2;
+
+	public string $foo = 'foo';
+}
+
+class SomeClass4
+{
+	use MyTrait2;
+
+	public int $foo = 1;
+}
+
+trait MyTrait2
+{
+	public function getRandom(): int
+	{
+		$value = random_int(1, 100);
+		if (\is_int($this->foo)) {
+			return $value * $value;
+		}
+
+		return $value;
+	}
+}