From 156dfe3d629f36a03bdcde3a9a253934e45dd4de Mon Sep 17 00:00:00 2001
From: davidot <davidot@serenityos.org>
Date: Fri, 26 Nov 2021 23:37:14 +0100
Subject: [PATCH] LibJS: Disallow member expression in binding pattern as
 parameters

---
 Userland/Libraries/LibJS/Parser.cpp                |  4 +++-
 .../LibJS/Tests/syntax/destructuring-assignment.js | 14 ++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Userland/Libraries/LibJS/Parser.cpp b/Userland/Libraries/LibJS/Parser.cpp
index c8f5690798..5379c891d5 100644
--- a/Userland/Libraries/LibJS/Parser.cpp
+++ b/Userland/Libraries/LibJS/Parser.cpp
@@ -2383,7 +2383,7 @@ Vector<FunctionNode::Parameter> Parser::parse_formal_parameters(int& function_le
     Vector<FunctionNode::Parameter> parameters;
 
     auto consume_identifier_or_binding_pattern = [&]() -> Variant<FlyString, NonnullRefPtr<BindingPattern>> {
-        if (auto pattern = parse_binding_pattern(AllowDuplicates::No, AllowMemberExpressions::Yes))
+        if (auto pattern = parse_binding_pattern(AllowDuplicates::No, AllowMemberExpressions::No))
             return pattern.release_nonnull();
 
         auto token = consume_identifier();
@@ -2635,6 +2635,8 @@ RefPtr<BindingPattern> Parser::parse_binding_pattern(Parser::AllowDuplicates all
                 return {};
             }
             consume();
+        } else if (is_object && !match(TokenType::CurlyClose)) {
+            consume(TokenType::Comma);
         }
     }
 
diff --git a/Userland/Libraries/LibJS/Tests/syntax/destructuring-assignment.js b/Userland/Libraries/LibJS/Tests/syntax/destructuring-assignment.js
index 7a709a31bb..198561c4a8 100644
--- a/Userland/Libraries/LibJS/Tests/syntax/destructuring-assignment.js
+++ b/Userland/Libraries/LibJS/Tests/syntax/destructuring-assignment.js
@@ -46,6 +46,20 @@ describe("parsing", () => {
         expect(`const [ a, [ ...{length} ] ] = [];`).toEval();
         expect(`let [ a, [ ...{length} ] ] = [];`).toEval();
     });
+
+    test("function parameters cannot use member expresssions", () => {
+        expect("function f([a.b]) {}").not.toEval();
+        expect("function f([b[0]]) {}").not.toEval();
+
+        expect("function f({c:a.b}) {}").not.toEval();
+        expect("function f({a:b[0]}) {}").not.toEval();
+
+        expect("([a.b]) => 1").not.toEval();
+        expect("([b[0]]) => 2").not.toEval();
+
+        expect("({c:a.b}) => 3").not.toEval();
+        expect("({a:b[0]}) => 4").not.toEval();
+    });
 });
 
 describe("evaluating", () => {