From 3ffb0a4e87366b128e6d7ad749bd7083f7016975 Mon Sep 17 00:00:00 2001
From: Jack Karamanian <karamanian.jack@gmail.com>
Date: Sat, 30 May 2020 00:16:42 -0500
Subject: [PATCH] LibJS: Throw a TypeError when an arrow function is used as a
 constructor

---
 Libraries/LibJS/Runtime/ScriptFunction.cpp | 2 ++
 Libraries/LibJS/Tests/arrow-functions.js   | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/Libraries/LibJS/Runtime/ScriptFunction.cpp b/Libraries/LibJS/Runtime/ScriptFunction.cpp
index 5828bcdde3..fddee25d2a 100644
--- a/Libraries/LibJS/Runtime/ScriptFunction.cpp
+++ b/Libraries/LibJS/Runtime/ScriptFunction.cpp
@@ -125,6 +125,8 @@ Value ScriptFunction::call(Interpreter& interpreter)
 
 Value ScriptFunction::construct(Interpreter& interpreter)
 {
+    if (m_is_arrow_function)
+        return interpreter.throw_exception<TypeError>(String::format("%s is not a constructor", m_name.characters()));
     return call(interpreter);
 }
 
diff --git a/Libraries/LibJS/Tests/arrow-functions.js b/Libraries/LibJS/Tests/arrow-functions.js
index e224415ded..add2c0a6fc 100644
--- a/Libraries/LibJS/Tests/arrow-functions.js
+++ b/Libraries/LibJS/Tests/arrow-functions.js
@@ -81,6 +81,13 @@ try {
 
     assert(Baz.prototype === undefined);
 
+    assertThrowsError(() => {
+        new Baz();
+    }, {
+        error: TypeError,
+        message: "Baz is not a constructor"
+    });
+
     (() => {
         "use strict";
         assert(isStrictMode());