From 5e75140ca575406d01df12d856c98ec12b565cc3 Mon Sep 17 00:00:00 2001
From: Matt Brown <github@muglug.com>
Date: Sun, 17 Jan 2021 14:28:28 -0500
Subject: [PATCH] Fix #5020 - remove previous catch var assertions when
 assigning inside catch

---
 src/Psalm/Context.php                         |  4 +++
 .../Analyzer/Statements/Block/TryAnalyzer.php |  8 +++++
 tests/Template/FunctionTemplateAssertTest.php | 35 +++++++++++++++++++
 3 files changed, 47 insertions(+)

diff --git a/src/Psalm/Context.php b/src/Psalm/Context.php
index f62616160..6a8af0cd0 100644
--- a/src/Psalm/Context.php
+++ b/src/Psalm/Context.php
@@ -630,6 +630,10 @@ class Context
         }
     }
 
+    /**
+     * This method is used after assignments to variables to remove any existing
+     * items in $vars_in_scope that are now made redundant by an update to some data
+     */
     public function removeDescendents(
         string $remove_var_id,
         ?Union $existing_type = null,
diff --git a/src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php
index 58399df1a..b5c1424b5 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php
@@ -306,6 +306,14 @@ class TryAnalyzer
                     )
                 );
 
+                // removes dependent vars from $context
+                $catch_context->removeDescendents(
+                    $catch_var_id,
+                    null,
+                    $catch_context->vars_in_scope[$catch_var_id],
+                    $statements_analyzer
+                );
+
                 $catch_context->vars_possibly_in_scope[$catch_var_id] = true;
 
                 $location = new CodeLocation($statements_analyzer->getSource(), $catch->var);
diff --git a/tests/Template/FunctionTemplateAssertTest.php b/tests/Template/FunctionTemplateAssertTest.php
index 00613e89b..eab898d6b 100644
--- a/tests/Template/FunctionTemplateAssertTest.php
+++ b/tests/Template/FunctionTemplateAssertTest.php
@@ -732,6 +732,41 @@ class FunctionTemplateAssertTest extends TestCase
                         }
                     }'
             ],
+            'assertSameOnMemoizedMethodCall' => [
+                '<?php
+                    function testValidUsername(): void {
+                        try {
+                            validateUsername("123");
+                            throw new Exception("Failed to throw exception for short username");
+                        } catch (Exception $e) {
+                            assertSame("a", $e->getMessage());
+                        }
+
+                        try {
+                            validateUsername("invalid#1");
+                        } catch (Exception $e) {
+                            assertSame("b", $e->getMessage());
+                        }
+                    }
+
+                    /**
+                     * @psalm-template ExpectedType
+                     * @psalm-param ExpectedType $expected
+                     * @psalm-param mixed $actual
+                     * @psalm-assert =ExpectedType $actual
+                     */
+                    function assertSame($expected, $actual): void {
+                        if ($actual !== $expected) {
+                            throw new Exception("Bad");
+                        }
+                    }
+
+                    function validateUsername(string $username): void {
+                        if (strlen($username) < 5) {
+                            throw new Exception("Username must be at least 5 characters long");
+                        }
+                    }'
+            ],
         ];
     }