From b0ae1e80fb023a9b17169f65f7586dbda0654956 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sun, 2 Jul 2023 11:24:55 +0200
Subject: [PATCH] LibJS/Bytecode: Support using MemberExpression as rest
 property

Also, don't assert while dumping an AST with this construct.

7 new passes on test262. :^)
---
 Userland/Libraries/LibJS/AST.cpp              |  6 ++++-
 .../Libraries/LibJS/Bytecode/ASTCodegen.cpp   | 25 +++++++++++--------
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/Userland/Libraries/LibJS/AST.cpp b/Userland/Libraries/LibJS/AST.cpp
index 9cab06633a..a6a1e5c764 100644
--- a/Userland/Libraries/LibJS/AST.cpp
+++ b/Userland/Libraries/LibJS/AST.cpp
@@ -2461,8 +2461,12 @@ void BindingPattern::dump(int indent) const
             outln("(Identifier)");
             if (entry.name.has<NonnullRefPtr<Identifier const>>()) {
                 entry.name.get<NonnullRefPtr<Identifier const>>()->dump(indent + 3);
-            } else {
+            } else if (entry.name.has<NonnullRefPtr<Expression const>>()) {
                 entry.name.get<NonnullRefPtr<Expression const>>()->dump(indent + 3);
+            } else {
+                VERIFY(entry.name.has<Empty>());
+                print_indent(indent + 3);
+                outln("<empty>");
             }
         } else if (entry.is_elision()) {
             print_indent(indent + 2);
diff --git a/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp b/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
index 5e962af277..b9618372cc 100644
--- a/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
@@ -1032,19 +1032,24 @@ static Bytecode::CodeGenerationErrorOr<void> generate_object_binding_pattern_byt
 
     for (auto& [name, alias, initializer, is_rest] : pattern.entries) {
         if (is_rest) {
-            VERIFY(name.has<NonnullRefPtr<Identifier const>>());
-            VERIFY(alias.has<Empty>());
             VERIFY(!initializer);
+            if (name.has<NonnullRefPtr<Identifier const>>()) {
+                auto identifier = name.get<NonnullRefPtr<Identifier const>>()->string();
+                auto interned_identifier = generator.intern_identifier(identifier);
 
-            auto identifier = name.get<NonnullRefPtr<Identifier const>>()->string();
-            auto interned_identifier = generator.intern_identifier(identifier);
+                generator.emit_with_extra_register_slots<Bytecode::Op::CopyObjectExcludingProperties>(excluded_property_names.size(), value_reg, excluded_property_names);
+                if (create_variables)
+                    generator.emit<Bytecode::Op::CreateVariable>(interned_identifier, Bytecode::Op::EnvironmentMode::Lexical, false);
+                generator.emit<Bytecode::Op::SetVariable>(interned_identifier, initialization_mode);
 
-            generator.emit_with_extra_register_slots<Bytecode::Op::CopyObjectExcludingProperties>(excluded_property_names.size(), value_reg, excluded_property_names);
-            if (create_variables)
-                generator.emit<Bytecode::Op::CreateVariable>(interned_identifier, Bytecode::Op::EnvironmentMode::Lexical, false);
-            generator.emit<Bytecode::Op::SetVariable>(interned_identifier, initialization_mode);
-
-            return {};
+                return {};
+            }
+            if (alias.has<NonnullRefPtr<MemberExpression const>>()) {
+                generator.emit_with_extra_register_slots<Bytecode::Op::CopyObjectExcludingProperties>(excluded_property_names.size(), value_reg, excluded_property_names);
+                TRY(generator.emit_store_to_reference(alias.get<NonnullRefPtr<MemberExpression const>>()));
+                return {};
+            }
+            VERIFY_NOT_REACHED();
         }
 
         Bytecode::StringTableIndex name_index;