From 26213d5465f06d41294f3fe60d1adab88dfdd636 Mon Sep 17 00:00:00 2001
From: Tomas Votruba <tomas.vot@gmail.com>
Date: Sun, 13 Oct 2019 01:24:47 +0200
Subject: [PATCH] make ReturnTypeDeclarationRector keep implementation

---
 .../Rector/FunctionLike/ReturnTypeDeclarationRector.php  | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/packages/TypeDeclaration/src/Rector/FunctionLike/ReturnTypeDeclarationRector.php b/packages/TypeDeclaration/src/Rector/FunctionLike/ReturnTypeDeclarationRector.php
index f1a61573053..1ad7b5f0988 100644
--- a/packages/TypeDeclaration/src/Rector/FunctionLike/ReturnTypeDeclarationRector.php
+++ b/packages/TypeDeclaration/src/Rector/FunctionLike/ReturnTypeDeclarationRector.php
@@ -134,6 +134,15 @@ PHP
         if ($node->returnType !== null) {
             $isSubtype = $this->isSubtypeOf($inferredReturnNode, $node->returnType);
 
+            $currentType = $this->staticTypeMapper->mapPhpParserNodePHPStanType($node->returnType);
+
+            // is current class implementation/subtype
+            if ($currentType instanceof ObjectType && $inferedType instanceof ObjectType) {
+                if (is_a($currentType->getClassName(), $inferedType->getClassName(), true)) {
+                    return null;
+                }
+            }
+
             // @see https://wiki.php.net/rfc/covariant-returns-and-contravariant-parameters
             if ($this->isAtLeastPhpVersion('7.4') && $isSubtype) {
                 $node->returnType = $inferredReturnNode;