From caac9049c40f7361ede282cf358d3c5981e5d6db Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=98=BF=E8=B1=AA?= <504595380@qq.com>
Date: Sat, 21 Oct 2023 15:25:18 +0800
Subject: [PATCH] Fix Array.join when the array contains itself (#3406)

* Fix Array.join when the array contains itself

* add test
---
 boa_engine/src/builtins/array/mod.rs   | 4 ++--
 boa_engine/src/builtins/array/tests.rs | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/boa_engine/src/builtins/array/mod.rs b/boa_engine/src/builtins/array/mod.rs
index 8c3f386707..05b7abc775 100644
--- a/boa_engine/src/builtins/array/mod.rs
+++ b/boa_engine/src/builtins/array/mod.rs
@@ -1000,8 +1000,8 @@ impl Array {
             }
             // b. Let element be ? Get(O, ! ToString(𝔽(k))).
             let element = o.get(k, context)?;
-            // c. If element is undefined or null, let next be the empty String; otherwise, let next be ? ToString(element).
-            let next = if element.is_null_or_undefined() {
+            // c. If element is undefined, null or the array itself, let next be the empty String; otherwise, let next be ? ToString(element).
+            let next = if element.is_null_or_undefined() || &element == this {
                 js_string!()
             } else {
                 element.to_string(context)?
diff --git a/boa_engine/src/builtins/array/tests.rs b/boa_engine/src/builtins/array/tests.rs
index d14b610e39..595f4d333c 100644
--- a/boa_engine/src/builtins/array/tests.rs
+++ b/boa_engine/src/builtins/array/tests.rs
@@ -77,6 +77,7 @@ fn join() {
         TestAction::assert_eq("[].join('.')", js_string!()),
         TestAction::assert_eq("['a'].join('.')", js_string!("a")),
         TestAction::assert_eq("['a', 'b', 'c'].join('.')", js_string!("a.b.c")),
+        TestAction::assert_eq("let a=[];a[0]=a;a[1]=a;a[2]=a;a.join()", js_string!(",,")),
     ]);
 }