From 85071b61a3955461e1493d13c1e0c5f3f78e7c01 Mon Sep 17 00:00:00 2001
From: Daniil Gentili <daniil@daniil.it>
Date: Thu, 24 Nov 2022 11:28:00 +0100
Subject: [PATCH 1/2] Fix #8748

---
 .../Expression/Call/Method/MethodCallPurityAnalyzer.php         | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
index 1b5859bd660..0fde9d86617 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Call/Method/MethodCallPurityAnalyzer.php
@@ -158,7 +158,7 @@ public static function analyze(
                     && !isset($class_storage->declaring_property_ids[$name]);
 
                 if ($this_property_didnt_exist) {
-                    $context->vars_in_scope[$mutation_var_id] = Type::getMixed();
+                    unset($context->vars_in_scope[$mutation_var_id]);
                 } else {
                     $new_type = AssignmentAnalyzer::getExpandedPropertyType(
                         $codebase,

From 5ac60ddea0427991ffbd5c25c8d984aad2ffbbea Mon Sep 17 00:00:00 2001
From: Daniil Gentili <daniil@daniil.it>
Date: Thu, 24 Nov 2022 19:31:53 +0100
Subject: [PATCH 2/2] Add tests

---
 tests/MagicPropertyTest.php | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/tests/MagicPropertyTest.php b/tests/MagicPropertyTest.php
index a6b9876dd27..445b3ee1f12 100644
--- a/tests/MagicPropertyTest.php
+++ b/tests/MagicPropertyTest.php
@@ -731,6 +731,41 @@ public function __set(string $_prop, $_value) {}
                     $a->type = A::TYPE_B;
                 ',
             ],
+            'impureMethodTest' => [
+                'code' => '<?php
+                    /**
+                     * @property array<string, string> $errors
+                     *
+                     * @psalm-seal-properties
+                     */
+                    final class OrganizationObject {
+
+                        public function __get(string $key)
+                        {
+                            return [];
+                        }
+
+                        /**
+                         * @param mixed $a
+                         */
+                        public function __set(string $key, $a): void
+                        {
+                        }
+
+                        public function updateErrors(): void {
+                            /** @var array<string, string> */
+                            $errors = [];
+                            $this->errors = $errors;
+                        }
+                        /** @return array<string, string> */
+                        public function updateStatus(): array {
+                            $_ = $this->errors;
+                            $this->updateErrors();
+                            $errors = $this->errors;
+                            return $errors;
+                        }
+                    }'
+            ]
         ];
     }