From e898c988737b012134bb4ba7e12c1db9eb48714e Mon Sep 17 00:00:00 2001
From: Linus Groh <mail@linusgroh.de>
Date: Mon, 19 Oct 2020 00:29:17 +0100
Subject: [PATCH] LibJS: Don't parse arrow function with newline between ) and
 =>

If there's a newline between the closing paren and arrow it's not a
valid arrow function, ASI should kick in instead (it'll then fail with
"Unexpected token Arrow")
---
 Libraries/LibJS/Parser.cpp                         | 4 ++++
 Libraries/LibJS/Tests/functions/arrow-functions.js | 1 +
 2 files changed, 5 insertions(+)

diff --git a/Libraries/LibJS/Parser.cpp b/Libraries/LibJS/Parser.cpp
index a612ff59e2..b725982005 100644
--- a/Libraries/LibJS/Parser.cpp
+++ b/Libraries/LibJS/Parser.cpp
@@ -353,6 +353,10 @@ RefPtr<FunctionExpression> Parser::try_parse_arrow_function_expression(bool expe
             return nullptr;
         parameters.append({ consume().value(), {} });
     }
+    // If there's a newline between the closing paren and arrow it's not a valid arrow function,
+    // ASI should kick in instead (it'll then fail with "Unexpected token Arrow")
+    if (m_parser_state.m_current_token.trivia().contains('\n'))
+        return nullptr;
     if (!match(TokenType::Arrow))
         return nullptr;
     consume();
diff --git a/Libraries/LibJS/Tests/functions/arrow-functions.js b/Libraries/LibJS/Tests/functions/arrow-functions.js
index cb741e2a17..6af8790514 100644
--- a/Libraries/LibJS/Tests/functions/arrow-functions.js
+++ b/Libraries/LibJS/Tests/functions/arrow-functions.js
@@ -160,4 +160,5 @@ test("syntax errors", () => {
     expect("(a b) => {}").not.toEval();
     expect("(a ...b) => {}").not.toEval();
     expect("(a = 1 = 2) => {}").not.toEval();
+    expect("()\n=> {}").not.toEval();
 });