LibJS: Convert create_immutable_binding() to ThrowCompletionOr

Also add spec step comments to it while we're here.

Userland/Libraries/LibJS/AST.cpp

@@ -192,7 +192,7 @@ Value FunctionExpression::instantiate_ordinary_function_expression(Interpreter&
     if (has_own_name) {
         VERIFY(scope);
         scope = new_declarative_environment(*scope);
-        scope->create_immutable_binding(global_object, name(), false);
+        MUST(scope->create_immutable_binding(global_object, name(), false));
     }
 
     auto closure = ECMAScriptFunctionObject::create(global_object, used_name, body(), parameters(), function_length(), scope, kind(), is_strict_mode(), might_need_arguments_object(), contains_direct_call_to_eval(), is_arrow_function());
@@ -543,7 +543,7 @@ Value ForStatement::execute(Interpreter& interpreter, GlobalObject& global_objec
             auto& declaration = static_cast<VariableDeclaration const&>(*m_init);
             declaration.for_each_bound_name([&](auto const& name) {
                 if (declaration.declaration_kind() == DeclarationKind::Const) {
-                    loop_environment->create_immutable_binding(global_object, name, true);
+                    MUST(loop_environment->create_immutable_binding(global_object, name, true));
                 } else {
                     MUST(loop_environment->create_mutable_binding(global_object, name, false));
                     let_declarations.append(name);
@@ -683,7 +683,7 @@ struct ForInOfHeadState {
             auto& for_declaration = static_cast<VariableDeclaration const&>(*expression_lhs);
             for_declaration.for_each_bound_name([&](auto const& name) {
                 if (for_declaration.declaration_kind() == DeclarationKind::Const)
-                    iteration_environment->create_immutable_binding(global_object, name, false);
+                    MUST(iteration_environment->create_immutable_binding(global_object, name, false));
                 else
                     MUST(iteration_environment->create_mutable_binding(global_object, name, true));
             });
@@ -1210,7 +1210,7 @@ ThrowCompletionOr<Value> ClassExpression::class_definition_evaluation(Interprete
     VERIFY(environment);
     auto* class_scope = new_declarative_environment(*environment);
     if (!binding_name.is_null())
-        class_scope->create_immutable_binding(global_object, binding_name, true);
+        MUST(class_scope->create_immutable_binding(global_object, binding_name, true));
 
     ArmedScopeGuard restore_environment = [&] {
         vm.running_execution_context().lexical_environment = environment;
@@ -3188,7 +3188,7 @@ void ScopeNode::block_declaration_instantiation(GlobalObject& global_object, Env
         auto is_constant_declaration = declaration.is_constant_declaration();
         declaration.for_each_bound_name([&](auto const& name) {
             if (is_constant_declaration) {
-                environment->create_immutable_binding(global_object, name, true);
+                MUST(environment->create_immutable_binding(global_object, name, true));
             } else {
                 if (!MUST(environment->has_binding(name)))
                     MUST(environment->create_mutable_binding(global_object, name, false));
@@ -3327,10 +3327,9 @@ ThrowCompletionOr<void> Program::global_declaration_instantiation(Interpreter& i
     for_each_lexically_scoped_declaration([&](Declaration const& declaration) {
         declaration.for_each_bound_name([&](auto const& name) {
             if (declaration.is_constant_declaration())
-                global_environment.create_immutable_binding(global_object, name, true);
+                (void)global_environment.create_immutable_binding(global_object, name, true);
             else
                 (void)global_environment.create_mutable_binding(global_object, name, false);
-
             if (interpreter.exception())
                 return IterationDecision::Break;
             return IterationDecision::Continue;

Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp

@@ -678,7 +678,7 @@ ThrowCompletionOr<void> eval_declaration_instantiation(VM& vm, GlobalObject& glo
     program.for_each_lexically_scoped_declaration([&](Declaration const& declaration) {
         declaration.for_each_bound_name([&](auto const& name) {
             if (declaration.is_constant_declaration())
-                lexical_environment->create_immutable_binding(global_object, name, true);
+                (void)lexical_environment->create_immutable_binding(global_object, name, true);
             else
                 (void)lexical_environment->create_mutable_binding(global_object, name, false);
             if (vm.exception())

Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.cpp

@@ -66,8 +66,9 @@ ThrowCompletionOr<void> DeclarativeEnvironment::create_mutable_binding(GlobalObj
 }
 
 // 9.1.1.1.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-createimmutablebinding-n-s
-void DeclarativeEnvironment::create_immutable_binding(GlobalObject&, FlyString const& name, bool strict)
+ThrowCompletionOr<void> DeclarativeEnvironment::create_immutable_binding(GlobalObject&, FlyString const& name, bool strict)
 {
+    // 2. Create an immutable binding in envRec for N and record that it is uninitialized. If S is true, record that the newly created binding is a strict binding.
     m_bindings.append(Binding {
         .value = {},
         .strict = strict,
@@ -76,7 +77,12 @@ void DeclarativeEnvironment::create_immutable_binding(GlobalObject&, FlyString c
         .initialized = false,
     });
     auto result = m_names.set(name, m_bindings.size() - 1);
+
+    // 1. Assert: envRec does not already have a binding for N.
     VERIFY(result == AK::HashSetResult::InsertedNewEntry);
+
+    // 3. Return NormalCompletion(empty).
+    return {};
 }
 
 // 9.1.1.1.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-declarative-environment-records-initializebinding-n-v

Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.h

@@ -24,7 +24,7 @@ public:
 
     virtual ThrowCompletionOr<bool> has_binding(FlyString const& name, Optional<size_t>* = nullptr) const override;
     virtual ThrowCompletionOr<void> create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
-    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual ThrowCompletionOr<void> create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
     virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
     virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
     virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;

Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp

@@ -374,7 +374,7 @@ ThrowCompletionOr<void> ECMAScriptFunctionObject::function_declaration_instantia
             arguments_object = create_mapped_arguments_object(global_object(), *this, formal_parameters(), vm.running_execution_context().arguments, *environment);
 
         if (is_strict_mode())
-            environment->create_immutable_binding(global_object(), vm.names.arguments.as_string(), false);
+            MUST(environment->create_immutable_binding(global_object(), vm.names.arguments.as_string(), false));
         else
             MUST(environment->create_mutable_binding(global_object(), vm.names.arguments.as_string(), false));
 
@@ -524,7 +524,7 @@ ThrowCompletionOr<void> ECMAScriptFunctionObject::function_declaration_instantia
     scope_body->for_each_lexically_scoped_declaration([&](Declaration const& declaration) {
         declaration.for_each_bound_name([&](auto const& name) {
             if (declaration.is_constant_declaration())
-                lex_environment->create_immutable_binding(global_object(), name, true);
+                MUST(lex_environment->create_immutable_binding(global_object(), name, true));
             else
                 MUST(lex_environment->create_mutable_binding(global_object(), name, false));
             return IterationDecision::Continue;

Userland/Libraries/LibJS/Runtime/Environment.h

@@ -35,7 +35,7 @@ public:
 
     virtual ThrowCompletionOr<bool> has_binding([[maybe_unused]] FlyString const& name, [[maybe_unused]] Optional<size_t>* out_index = nullptr) const { return false; }
     virtual ThrowCompletionOr<void> create_mutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool can_be_deleted) { return {}; }
-    virtual void create_immutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool strict) { }
+    virtual ThrowCompletionOr<void> create_immutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool strict) { return {}; }
     virtual void initialize_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, Value) { }
     virtual void set_mutable_binding(GlobalObject&, [[maybe_unused]] FlyString const& name, Value, [[maybe_unused]] bool strict) { }
     virtual Value get_binding_value(GlobalObject&, [[maybe_unused]] FlyString const& name, [[maybe_unused]] bool strict) { return {}; }

Userland/Libraries/LibJS/Runtime/GlobalEnvironment.cpp

@@ -64,13 +64,15 @@ ThrowCompletionOr<void> GlobalEnvironment::create_mutable_binding(GlobalObject&
 }
 
 // 9.1.1.4.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-global-environment-records-createimmutablebinding-n-s
-void GlobalEnvironment::create_immutable_binding(GlobalObject& global_object, FlyString const& name, bool strict)
+ThrowCompletionOr<void> GlobalEnvironment::create_immutable_binding(GlobalObject& global_object, FlyString const& name, bool strict)
 {
-    if (MUST(m_declarative_record->has_binding(name))) {
-        global_object.vm().throw_exception<TypeError>(global_object, ErrorType::FixmeAddAnErrorString);
-        return;
-    }
-    m_declarative_record->create_immutable_binding(global_object, name, strict);
+    // 1. Let DclRec be envRec.[[DeclarativeRecord]].
+    // 2. If DclRec.HasBinding(N) is true, throw a TypeError exception.
+    if (MUST(m_declarative_record->has_binding(name)))
+        return vm().throw_completion<TypeError>(global_object, ErrorType::FixmeAddAnErrorString);
+
+    // 3. Return DclRec.CreateImmutableBinding(N, S).
+    return m_declarative_record->create_immutable_binding(global_object, name, strict);
 }
 
 // 9.1.1.4.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-global-environment-records-initializebinding-n-v

Userland/Libraries/LibJS/Runtime/GlobalEnvironment.h

@@ -21,7 +21,7 @@ public:
 
     virtual ThrowCompletionOr<bool> has_binding(FlyString const& name, Optional<size_t>* = nullptr) const override;
     virtual ThrowCompletionOr<void> create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
-    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual ThrowCompletionOr<void> create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
     virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
     virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
     virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;

Userland/Libraries/LibJS/Runtime/ObjectEnvironment.cpp

@@ -69,7 +69,7 @@ ThrowCompletionOr<void> ObjectEnvironment::create_mutable_binding(GlobalObject&,
 }
 
 // 9.1.1.2.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-object-environment-records-createimmutablebinding-n-s
-void ObjectEnvironment::create_immutable_binding(GlobalObject&, FlyString const&, bool)
+ThrowCompletionOr<void> ObjectEnvironment::create_immutable_binding(GlobalObject&, FlyString const&, bool)
 {
     // "The CreateImmutableBinding concrete method of an object Environment Record is never used within this specification."
     VERIFY_NOT_REACHED();

Userland/Libraries/LibJS/Runtime/ObjectEnvironment.h

@@ -22,7 +22,7 @@ public:
 
     virtual ThrowCompletionOr<bool> has_binding(FlyString const& name, Optional<size_t>* = nullptr) const override;
     virtual ThrowCompletionOr<void> create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted) override;
-    virtual void create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
+    virtual ThrowCompletionOr<void> create_immutable_binding(GlobalObject&, FlyString const& name, bool strict) override;
     virtual void initialize_binding(GlobalObject&, FlyString const& name, Value) override;
     virtual void set_mutable_binding(GlobalObject&, FlyString const& name, Value, bool strict) override;
     virtual Value get_binding_value(GlobalObject&, FlyString const& name, bool strict) override;