From eae1a7022dc86290e2ea83819a22149e41fabcfb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Tomulik?= <pawel@tomulik.pl>
Date: Sun, 26 Feb 2023 23:48:55 +0100
Subject: [PATCH] fixed #9401

---
 src/Psalm/Internal/TypeVisitor/TypeChecker.php | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/Psalm/Internal/TypeVisitor/TypeChecker.php b/src/Psalm/Internal/TypeVisitor/TypeChecker.php
index d135de1be72..4c2e52c916b 100644
--- a/src/Psalm/Internal/TypeVisitor/TypeChecker.php
+++ b/src/Psalm/Internal/TypeVisitor/TypeChecker.php
@@ -348,6 +348,7 @@ public function checkTemplateParam(TTemplateParam $atomic): void
     {
         if ($this->prevent_template_covariance
             && strpos($atomic->defining_class, 'fn-') !== 0
+            && $atomic->defining_class !== 'class-string-map'
         ) {
             $codebase = $this->source->getCodebase();