From 4d7e79fb72c33bf341688428948c3c8e90898960 Mon Sep 17 00:00:00 2001
From: davidot <davidot@serenityos.org>
Date: Fri, 26 Nov 2021 23:38:36 +0100
Subject: [PATCH] LibJS: Stop parsing an expression on comma after a yield

---
 Userland/Libraries/LibJS/Parser.cpp                 | 2 +-
 Userland/Libraries/LibJS/Tests/syntax/generators.js | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/Userland/Libraries/LibJS/Parser.cpp b/Userland/Libraries/LibJS/Parser.cpp
index 5379c891d5..cb758c802c 100644
--- a/Userland/Libraries/LibJS/Parser.cpp
+++ b/Userland/Libraries/LibJS/Parser.cpp
@@ -2153,7 +2153,7 @@ NonnullRefPtr<YieldExpression> Parser::parse_yield_expression()
         }
 
         if (yield_from || match_expression() || match(TokenType::Class))
-            argument = parse_expression(0);
+            argument = parse_expression(2);
     }
 
     return create_ast_node<YieldExpression>({ m_state.current_token.filename(), rule_start.position(), position() }, move(argument), yield_from);
diff --git a/Userland/Libraries/LibJS/Tests/syntax/generators.js b/Userland/Libraries/LibJS/Tests/syntax/generators.js
index 99e0968c4b..c70bc6cf72 100644
--- a/Userland/Libraries/LibJS/Tests/syntax/generators.js
+++ b/Userland/Libraries/LibJS/Tests/syntax/generators.js
@@ -12,6 +12,12 @@ describe("parsing freestanding generators", () => {
         expect(`function foo() { yield; }`).toEval();
         expect(`function foo() { yield 3; }`).not.toEval();
     });
+
+    test("yield expression only gets the first expression", () => {
+        expect("function* foo() { yield 2,3 }").toEval();
+        expect("function* foo() { ({...yield yield, }) }").toEval();
+    });
+
     test("yield-from expression", () => {
         expect(`function* foo() { yield *bar; }`).toEval();
         expect(`function* foo() { yield *(yield); }`).toEval();