From 8b9de8bba62eb938602a1d83e594b3f50b568432 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Sun, 26 May 2019 13:16:44 -0400
Subject: [PATCH] =?UTF-8?q?class=5Fesists=20check=20with=20false=20arg=20s?=
 =?UTF-8?q?houldn=E2=80=99t=20count?=
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Fixes #1682
---
 .../Statements/Expression/AssertionFinder.php      | 13 ++++++++++++-
 tests/ClassTest.php                                | 14 ++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php b/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php
index 6060888ff..f83203e7a 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php
@@ -2296,7 +2296,18 @@ class AssertionFinder
         if ($stmt->name instanceof PhpParser\Node\Name
             && strtolower($stmt->name->parts[0]) === 'class_exists'
         ) {
-            return true;
+            if (!isset($stmt->args[2])) {
+                return true;
+            }
+
+            $second_arg = $stmt->args[2]->value;
+
+            if ($second_arg instanceof PhpParser\Node\Expr\ConstFetch
+                && $second_arg->name instanceof PhpParser\Node\Name
+                && strtolower($second_arg->name->parts[0]) === 'true'
+            ) {
+                return true;
+            }
         }
 
         return false;
diff --git a/tests/ClassTest.php b/tests/ClassTest.php
index b09082910..606aa35bb 100644
--- a/tests/ClassTest.php
+++ b/tests/ClassTest.php
@@ -391,6 +391,20 @@ class ClassTest extends TestCase
                         if (class_exists($s) || interface_exists($s)) {}
                     }'
             ],
+            'classExistsWithFalseArg' => [
+                '<?php
+                    /**
+                     * @param class-string $class
+                     * @return ?class-string
+                     */
+                    function autoload(string $class) : string {
+                        if (class_exists($class, false)) {
+                            return $class;
+                        }
+
+                        return $class;
+                    }'
+            ],
         ];
     }