Fix internal error

Author: ondrejmirtes

src/Reflection/ClassReflection.php

@@ -1587,7 +1587,7 @@ public function getTraitContextResolvedPhpDoc(self $implementingClass): ?Resolve
 		if (!$this->isTrait()) {
 			throw new ShouldNotHappenException();
 		}
-		if (!$implementingClass->isClass()) {
+		if ($implementingClass->isTrait()) {
 			throw new ShouldNotHappenException();
 		}
 		$fileName = $this->getFileName();

tests/PHPStan/Rules/Classes/MethodTagTraitUseRuleTest.php

@@ -10,6 +10,7 @@
 use PHPStan\Rules\PhpDoc\UnresolvableTypeHelper;
 use PHPStan\Rules\Rule as TRule;
 use PHPStan\Testing\RuleTestCase;
+use const PHP_VERSION_ID;
 
 /**
  * @extends RuleTestCase<MethodTagTraitUseRule>
@@ -56,6 +57,21 @@ public function testRule(): void
 		]);
 	}
 
+	public function testEnum(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			self::markTestSkipped('Test requires PHP 8.1.');
+		}
+
+		$this->analyse([__DIR__ . '/data/method-tag-trait-enum.php'], [
+			[
+				'PHPDoc tag @method for method MethodTagTraitEnum\Foo::doFoo() return type contains unknown class MethodTagTraitEnum\intt.',
+				8,
+				'Learn more at https://phpstan.org/user-guide/discovering-symbols',
+			],
+		]);
+	}
+
 	public function testBug11591(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-11591-method-tag.php'], []);

tests/PHPStan/Rules/Classes/data/method-tag-trait-enum.php

@@ -0,0 +1,18 @@
+<?php // lint >= 8.1
+
+namespace MethodTagTraitEnum;
+
+/**
+ * @method intt doFoo()
+ */
+trait Foo
+{
+
+}
+
+enum FooEnum
+{
+
+	use Foo;
+
+}