Add regression tests for trait-related false positives

Add test data files for phpstan/phpstan#7599, #9095, #13474, and #13687
to document and prevent regressions in trait type checking behavior.

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

Author: phpstan-bot

tests/PHPStan/Rules/Comparison/data/bug-13474.php

@@ -0,0 +1,86 @@
+<?php // lint >= 8.0
+
+namespace Bug13474;
+
+/**
+ * @template TValue of mixed
+ */
+interface ModelInterface {
+	/**
+	 * @return TValue
+	 */
+	public function getValue(): mixed;
+}
+
+/**
+ * @implements ModelInterface<int>
+ */
+class ModelA implements ModelInterface
+{
+	public function getValue(): int
+	{
+		return 0;
+	}
+}
+
+/**
+ * @implements ModelInterface<string>
+ */
+class ModelB implements ModelInterface
+{
+	public function getValue(): string
+	{
+		return 'foo';
+	}
+}
+
+/**
+ * @template T of ModelInterface
+ */
+trait ModelTrait
+{
+	/**
+	 * @return T
+	 */
+	abstract function model(): ModelInterface;
+
+	/**
+	 * @return template-type<T, ModelInterface, 'TValue'>
+	 */
+	public function getValue(): mixed
+	{
+		return $this->model()->getValue();
+	}
+
+	public function test(): void
+	{
+		if (is_string($this->getValue())) {
+			echo 'string';
+			return;
+		}
+
+		echo 'other';
+	}
+}
+
+class TestA
+{
+	/** @use ModelTrait<ModelA> */
+	use ModelTrait;
+
+	function model(): ModelA
+	{
+		return new ModelA();
+	}
+}
+
+class TestB
+{
+	/** @use ModelTrait<ModelB> */
+	use ModelTrait;
+
+	function model(): ModelB
+	{
+		return new ModelB();
+	}
+}

tests/PHPStan/Rules/Comparison/data/bug-13687.php

@@ -0,0 +1,29 @@
+<?php declare(strict_types = 1);
+
+namespace Bug13687;
+
+trait MyTrait {
+	public function foo(): void {
+		if (method_exists($this, 'bar')) {
+			$this->bar();
+		}
+
+		if (property_exists($this, 'baz')) {
+			$a = $this->baz;
+		}
+	}
+}
+
+class A {
+	use MyTrait;
+
+	public string $baz = 'baz';
+}
+
+class B {
+	use MyTrait;
+
+	public function bar(): void {
+		echo 'bar';
+	}
+}

tests/PHPStan/Rules/Comparison/data/bug-7599.php

@@ -0,0 +1,39 @@
+<?php // lint >= 8.1
+
+namespace Bug7599;
+
+trait TraitForEnum
+{
+	/**
+	 * @return array<int, string>
+	 */
+	public static function fooMethod(): array
+	{
+		return array_map(
+			fn(self $enum): string => method_exists($enum, 'barMethod')
+				? $enum->barMethod()
+				: $enum->name,
+			static::cases()
+		);
+	}
+}
+
+enum TestEnum: string
+{
+	use TraitForEnum;
+
+	case Foo = 'foo';
+	case Bar = 'bar';
+}
+
+enum SecondEnum: string
+{
+	use TraitForEnum;
+
+	case Baz = 'baz';
+
+	public function barMethod(): string
+	{
+		return 'blah';
+	}
+}

tests/PHPStan/Rules/Comparison/data/bug-9095.php

@@ -0,0 +1,23 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9095;
+
+trait EventTrait
+{
+	public function getCreatedAt(): ?\DateTimeInterface
+	{
+		if (
+			property_exists(static::class, 'createdAt') &&
+			isset($this->createdAt) &&
+			$this->createdAt instanceof \DateTimeInterface
+		) {
+			return $this->createdAt;
+		}
+		return null;
+	}
+}
+
+final class Event
+{
+	use EventTrait;
+}