From 7e67366a9b71f6fe52a09bdbadf75f167551f9f0 Mon Sep 17 00:00:00 2001
From: Nikita Popov <nikita.ppv@gmail.com>
Date: Thu, 4 Nov 2021 16:58:24 +0100
Subject: [PATCH] Remove unnecessary assertion

zend_class_implements_interface works fine if the "class" is an
interface, so simply drop this assertion. This avoids the need to
special case this situation.
---
 Zend/tests/interface_with_tostring.phpt | 18 ++++++++++++++++++
 Zend/zend_operators.c                   |  1 -
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 Zend/tests/interface_with_tostring.phpt

diff --git a/Zend/tests/interface_with_tostring.phpt b/Zend/tests/interface_with_tostring.phpt
new file mode 100644
index 00000000000..a7771c5e27a
--- /dev/null
+++ b/Zend/tests/interface_with_tostring.phpt
@@ -0,0 +1,18 @@
+--TEST--
+Interface with __toString() method
+--FILE--
+<?php
+
+interface MyStringable {
+    public function __toString(): string;
+}
+
+$rc = new ReflectionClass(MyStringable::class);
+var_dump($rc->getInterfaceNames());
+
+?>
+--EXPECT--
+array(1) {
+  [0]=>
+  string(10) "Stringable"
+}
diff --git a/Zend/zend_operators.c b/Zend/zend_operators.c
index ee86f9e96d3..acda841979e 100644
--- a/Zend/zend_operators.c
+++ b/Zend/zend_operators.c
@@ -2276,7 +2276,6 @@ ZEND_API zend_result ZEND_FASTCALL is_smaller_or_equal_function(zval *result, zv
 ZEND_API zend_bool ZEND_FASTCALL zend_class_implements_interface(const zend_class_entry *class_ce, const zend_class_entry *interface_ce) /* {{{ */
 {
 	uint32_t i;
-	ZEND_ASSERT(!(class_ce->ce_flags & ZEND_ACC_INTERFACE));
 	ZEND_ASSERT(interface_ce->ce_flags & ZEND_ACC_INTERFACE);
 
 	if (class_ce->num_interfaces) {