Regression test

Closes phpstan/phpstan#9657

Author: ondrejmirtes

tests/PHPStan/Rules/Methods/MissingMethodReturnTypehintRuleTest.php

@@ -5,6 +5,7 @@
 use PHPStan\Rules\MissingTypehintCheck;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
+use const PHP_VERSION_ID;
 
 /**
  * @extends RuleTestCase<MissingMethodReturnTypehintRule>
@@ -111,4 +112,13 @@ public function testGenericStatic(): void
 		]);
 	}
 
+	public function testBug9657(): void
+	{
+		if (PHP_VERSION_ID < 80000) {
+			$this->markTestSkipped('Test requires PHP 8.0');
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-9657.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-9657.php

@@ -0,0 +1,25 @@
+<?php // lint >= 8.0
+
+namespace Bug9657;
+
+/**
+ * @template T
+ */
+trait Convertable
+{
+	/**
+	 * @return T
+	 */
+	abstract public function toOther(): mixed;
+}
+
+final class Thing
+{
+	/** @use Convertable<list<never>> */
+	use Convertable;
+
+	public function toOther(): array
+	{
+		return [];
+	}
+}