From 2d8212cb52e3ebe694775677da68b3b97e7a1a57 Mon Sep 17 00:00:00 2001
From: Alies Lapatsin <web.lapateen@gmail.com>
Date: Wed, 8 Oct 2025 21:00:02 +0200
Subject: [PATCH] Support $this as a valid traversable parameter type

---
 .../Helpers/AnnotationTypeHelper.php          |  4 ++
 .../TypeHints/ReturnTypeHintSniffTest.php     | 14 +++++
 .../returnTypeHintWithTraversableNoErrors.php | 51 +++++++++++++++++++
 3 files changed, 69 insertions(+)
 create mode 100644 tests/Sniffs/TypeHints/data/returnTypeHintWithTraversableNoErrors.php

diff --git a/SlevomatCodingStandard/Helpers/AnnotationTypeHelper.php b/SlevomatCodingStandard/Helpers/AnnotationTypeHelper.php
index 972b47337..c8eeb3c40 100644
--- a/SlevomatCodingStandard/Helpers/AnnotationTypeHelper.php
+++ b/SlevomatCodingStandard/Helpers/AnnotationTypeHelper.php
@@ -227,6 +227,10 @@ public static function containsItemsSpecificationForTraversable(
 			);
 		}
 
+		if ($typeNode instanceof ThisTypeNode) {
+			return $inTraversable;
+		}
+
 		if ($typeNode instanceof ConstTypeNode) {
 			return $inTraversable;
 		}
diff --git a/tests/Sniffs/TypeHints/ReturnTypeHintSniffTest.php b/tests/Sniffs/TypeHints/ReturnTypeHintSniffTest.php
index f44ad418f..01ed5cb4f 100644
--- a/tests/Sniffs/TypeHints/ReturnTypeHintSniffTest.php
+++ b/tests/Sniffs/TypeHints/ReturnTypeHintSniffTest.php
@@ -240,4 +240,18 @@ public function testWithNullTrueFalseErrors(): void
 		self::assertAllFixedInFile($report);
 	}
 
+	public function testWithThisInGenericsNoErrors(): void
+	{
+		$report = self::checkFile(__DIR__ . '/data/returnTypeHintWithTraversableNoErrors.php', [
+			'enableObjectTypeHint' => true,
+			'enableMixedTypeHint' => true,
+			'enableUnionTypeHint' => false,
+			'enableIntersectionTypeHint' => false,
+			'enableNeverTypeHint' => false,
+			'enableStandaloneNullTrueFalseTypeHints' => false,
+			'traversableTypeHints' => ['Generic'],
+		]);
+		self::assertNoSniffErrorInFile($report);
+	}
+
 }
diff --git a/tests/Sniffs/TypeHints/data/returnTypeHintWithTraversableNoErrors.php b/tests/Sniffs/TypeHints/data/returnTypeHintWithTraversableNoErrors.php
new file mode 100644
index 000000000..2cb0b7b02
--- /dev/null
+++ b/tests/Sniffs/TypeHints/data/returnTypeHintWithTraversableNoErrors.php
@@ -0,0 +1,51 @@
+<?php // lint >= 8.0
+
+namespace FooNamespace;
+
+/**
+ * @template T
+ * @template U
+ */
+class Generic
+{
+}
+
+class Bar
+{
+}
+
+class Whatever
+{
+
+    /**
+     * @return Generic<Bar, $this>
+     */
+    public function withThisTemplateType(): Generic
+    {
+        return new Generic();
+    }
+
+    /**
+     * @return Generic<Bar, self>
+     */
+    public function withSelfTemplateType(): Generic
+    {
+        return new Generic();
+    }
+
+    /**
+     * @return Generic<Bar, static>
+     */
+    public function withStaticTemplateType(): Generic
+    {
+        return new Generic();
+    }
+
+    /**
+     * @return Generic<$this, Bar>
+     */
+    public function withThisAsFirstParam(): Generic
+    {
+        return new Generic();
+    }
+}