Everywhere: Remove unnecessary mutable attributes from lambdas

These lambdas were marked mutable as they captured a Ptr wrapper
class by value, which then only returned const-qualified references
to the value they point from the previous const pointer operators.

Nothing is actually mutating in the lambdas state here, and now
that the Ptr operators don't add extra const qualifiers these
can be removed.

Userland/Applications/MouseSettings/ThemeWidget.cpp

@@ -119,7 +119,7 @@ ThemeWidget::ThemeWidget()
     m_mouse_cursor_model->change_theme(theme_name);
 
     m_theme_name_box = find_descendant_of_type_named<GUI::ComboBox>("theme_name_box");
-    m_theme_name_box->on_change = [this](String const& value, GUI::ModelIndex const&) mutable {
+    m_theme_name_box->on_change = [this](String const& value, GUI::ModelIndex const&) {
         m_mouse_cursor_model->change_theme(value);
         set_modified(true);
     };

Userland/Applications/Terminal/main.cpp

@@ -199,18 +199,18 @@ static ErrorOr<NonnullRefPtr<GUI::Window>> create_find_window(VT::TerminalWidget
     find_forwards->set_fixed_width(25);
     find_forwards->set_icon(TRY(Gfx::Bitmap::try_load_from_file("/res/icons/16x16/downward-triangle.png"sv)));
 
-    find_textbox->on_return_pressed = [find_backwards]() mutable {
+    find_textbox->on_return_pressed = [find_backwards] {
         find_backwards->click();
     };
 
-    find_textbox->on_shift_return_pressed = [find_forwards]() mutable {
+    find_textbox->on_shift_return_pressed = [find_forwards] {
         find_forwards->click();
     };
 
     auto match_case = TRY(main_widget->try_add<GUI::CheckBox>("Case sensitive"));
     auto wrap_around = TRY(main_widget->try_add<GUI::CheckBox>("Wrap around"));
 
-    find_backwards->on_click = [&terminal, find_textbox, match_case, wrap_around](auto) mutable {
+    find_backwards->on_click = [&terminal, find_textbox, match_case, wrap_around](auto) {
         auto needle = find_textbox->text();
         if (needle.is_empty()) {
             return;

Userland/Libraries/LibCore/Promise.h

@@ -42,7 +42,7 @@ public:
     RefPtr<Promise<T>> map(T func(Result&))
     {
         RefPtr<Promise<T>> new_promise = Promise<T>::construct();
-        on_resolved = [new_promise, func](Result& result) mutable {
+        on_resolved = [new_promise, func](Result& result) {
             auto t = func(result);
             new_promise->resolve(move(t));
         };

Userland/Libraries/LibGUI/SettingsWindow.cpp

@@ -47,7 +47,7 @@ ErrorOr<NonnullRefPtr<SettingsWindow>> SettingsWindow::create(String title, Show
 
     if (show_defaults_button == ShowDefaultsButton::Yes) {
         window->m_reset_button = TRY(button_container->try_add<GUI::DialogButton>("Defaults"));
-        window->m_reset_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) mutable {
+        window->m_reset_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) {
             window->reset_default_values();
         };
     }
@@ -55,24 +55,24 @@ ErrorOr<NonnullRefPtr<SettingsWindow>> SettingsWindow::create(String title, Show
     TRY(button_container->layout()->try_add_spacer());
 
     window->m_ok_button = TRY(button_container->try_add<GUI::DialogButton>("OK"));
-    window->m_ok_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) mutable {
+    window->m_ok_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) {
         window->apply_settings();
         GUI::Application::the()->quit();
     };
 
     window->m_cancel_button = TRY(button_container->try_add<GUI::DialogButton>("Cancel"));
-    window->m_cancel_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) mutable {
+    window->m_cancel_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) {
         window->cancel_settings();
         GUI::Application::the()->quit();
     };
 
     window->m_apply_button = TRY(button_container->try_add<GUI::DialogButton>("Apply"));
     window->m_apply_button->set_enabled(false);
-    window->m_apply_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) mutable {
+    window->m_apply_button->on_click = [window = window->make_weak_ptr<SettingsWindow>()](auto) {
         window->apply_settings();
     };
 
-    window->on_close_request = [window = window->make_weak_ptr<SettingsWindow>()]() mutable -> Window::CloseRequestDecision {
+    window->on_close_request = [window = window->make_weak_ptr<SettingsWindow>()]() -> Window::CloseRequestDecision {
         if (!window->is_modified())
             return Window::CloseRequestDecision::Close;
 

Userland/Libraries/LibIDL/IDLParser.cpp

@@ -114,7 +114,7 @@ HashMap<String, String> Parser::parse_extended_attributes()
         if (lexer.consume_specific('=')) {
             bool did_open_paren = false;
             auto value = lexer.consume_until(
-                [&did_open_paren](auto ch) mutable {
+                [&did_open_paren](auto ch) {
                     if (ch == '(') {
                         did_open_paren = true;
                         return false;

Userland/Libraries/LibIPC/Connection.cpp

@@ -172,7 +172,7 @@ ErrorOr<Vector<u8>> ConnectionBase::read_as_much_as_possible_from_socket_without
 
         auto bytes_read = maybe_bytes_read.release_value();
         if (bytes_read.is_empty()) {
-            m_deferred_invoker->schedule([strong_this = NonnullRefPtr(*this)]() mutable {
+            m_deferred_invoker->schedule([strong_this = NonnullRefPtr(*this)] {
                 strong_this->shutdown();
             });
             if (!bytes.is_empty())
@@ -211,7 +211,7 @@ ErrorOr<void> ConnectionBase::drain_messages_from_peer()
     }
 
     if (!m_unprocessed_messages.is_empty()) {
-        m_deferred_invoker->schedule([strong_this = NonnullRefPtr(*this)]() mutable {
+        m_deferred_invoker->schedule([strong_this = NonnullRefPtr(*this)] {
             strong_this->handle_messages();
         });
     }

Userland/Libraries/LibJS/Runtime/PromiseJobs.cpp

@@ -92,7 +92,7 @@ PromiseJob create_promise_reaction_job(VM& vm, PromiseReaction& reaction, Value
 {
     // 1. Let job be a new Job Abstract Closure with no parameters that captures reaction and argument and performs the following steps when called:
     //    See run_reaction_job for "the following steps".
-    auto job = [&vm, reaction = make_handle(&reaction), argument = make_handle(argument)]() mutable {
+    auto job = [&vm, reaction = make_handle(&reaction), argument = make_handle(argument)] {
         return run_reaction_job(vm, *reaction.cell(), argument.value());
     };
 

Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp

@@ -128,7 +128,7 @@ JS::VM& main_thread_vm()
 
                 // 5. Queue a global task on the DOM manipulation task source given global to fire an event named rejectionhandled at global, using PromiseRejectionEvent,
                 //    with the promise attribute initialized to promise, and the reason attribute initialized to the value of promise's [[PromiseResult]] internal slot.
-                HTML::queue_global_task(HTML::Task::Source::DOMManipulation, global, [&global, &promise]() mutable {
+                HTML::queue_global_task(HTML::Task::Source::DOMManipulation, global, [&global, &promise] {
                     // FIXME: This currently assumes that global is a WindowObject.
                     auto& window = verify_cast<HTML::Window>(global);
 
@@ -178,12 +178,12 @@ JS::VM& main_thread_vm()
         };
 
         // 8.1.5.4.2 HostEnqueueFinalizationRegistryCleanupJob(finalizationRegistry), https://html.spec.whatwg.org/multipage/webappapis.html#hostenqueuefinalizationregistrycleanupjob
-        vm->host_enqueue_finalization_registry_cleanup_job = [](JS::FinalizationRegistry& finalization_registry) mutable {
+        vm->host_enqueue_finalization_registry_cleanup_job = [](JS::FinalizationRegistry& finalization_registry) {
             // 1. Let global be finalizationRegistry.[[Realm]]'s global object.
             auto& global = finalization_registry.realm().global_object();
 
             // 2. Queue a global task on the JavaScript engine task source given global to perform the following steps:
-            HTML::queue_global_task(HTML::Task::Source::JavaScriptEngine, global, [&finalization_registry]() mutable {
+            HTML::queue_global_task(HTML::Task::Source::JavaScriptEngine, global, [&finalization_registry] {
                 // 1. Let entry be finalizationRegistry.[[CleanupCallback]].[[Callback]].[[Realm]]'s environment settings object.
                 auto& entry = host_defined_environment_settings_object(*finalization_registry.cleanup_callback().callback.cell()->realm());
 
@@ -224,7 +224,7 @@ JS::VM& main_thread_vm()
             auto* script = active_script();
 
             // NOTE: This keeps job_settings alive by keeping realm alive, which is holding onto job_settings.
-            HTML::queue_a_microtask(script ? script->settings_object().responsible_document().ptr() : nullptr, [job_settings, job = move(job), script_or_module = move(script_or_module)]() mutable {
+            HTML::queue_a_microtask(script ? script->settings_object().responsible_document().ptr() : nullptr, [job_settings, job = move(job), script_or_module = move(script_or_module)] {
                 // The dummy execution context has to be kept up here to keep it alive for the duration of the function.
                 Optional<JS::ExecutionContext> dummy_execution_context;
 

Userland/Libraries/LibWeb/DOM/AbortSignal.cpp

@@ -101,7 +101,7 @@ void AbortSignal::follow(JS::NonnullGCPtr<AbortSignal> parent_signal)
 
     // 3. Otherwise, add the following abort steps to parentSignal:
     // NOTE: `this` and `parent_signal` are protected by AbortSignal using JS::SafeFunction.
-    parent_signal->add_abort_algorithm([this, parent_signal]() mutable {
+    parent_signal->add_abort_algorithm([this, parent_signal] {
         // 1. Signal abort on followingSignal with parentSignal’s abort reason.
         signal_abort(parent_signal->reason());
     });

Userland/Libraries/LibWeb/DOM/Document.cpp

@@ -1559,13 +1559,13 @@ void Document::completely_finish_loading()
 
     // 4. If container is an iframe element, then queue an element task on the DOM manipulation task source given container to run the iframe load event steps given container.
     if (container && is<HTML::HTMLIFrameElement>(*container)) {
-        container->queue_an_element_task(HTML::Task::Source::DOMManipulation, [container]() mutable {
+        container->queue_an_element_task(HTML::Task::Source::DOMManipulation, [container] {
             run_iframe_load_event_steps(static_cast<HTML::HTMLIFrameElement&>(*container));
         });
     }
     // 5. Otherwise, if container is non-null, then queue an element task on the DOM manipulation task source given container to fire an event named load at container.
     else if (container) {
-        container->queue_an_element_task(HTML::Task::Source::DOMManipulation, [container]() mutable {
+        container->queue_an_element_task(HTML::Task::Source::DOMManipulation, [container] {
             container->dispatch_event(*DOM::Event::create(container->realm(), HTML::EventNames::load));
         });
     }

Userland/Libraries/LibWeb/DOM/EventTarget.cpp

@@ -171,7 +171,7 @@ void EventTarget::add_an_event_listener(DOMEventListener& listener)
     // 5. If listener’s signal is not null, then add the following abort steps to it:
     if (listener.signal) {
         // NOTE: `this` and `listener` are protected by AbortSignal using JS::SafeFunction.
-        listener.signal->add_abort_algorithm([this, &listener]() mutable {
+        listener.signal->add_abort_algorithm([this, &listener] {
             // 1. Remove an event listener with eventTarget and listener.
             remove_an_event_listener(listener);
         });

Userland/Libraries/LibWeb/Fetch/FetchMethod.cpp

@@ -125,7 +125,7 @@ JS::NonnullGCPtr<JS::Promise> fetch_impl(JS::VM& vm, RequestInfo const& input, R
             })));
 
     // 11. Add the following abort steps to requestObject’s signal:
-    request_object->signal()->add_abort_algorithm([&vm, locally_aborted, request, controller, promise_capability_handle = JS::make_handle(*promise_capability), request_object_handle = JS::make_handle(*request_object), response_object_handle]() mutable {
+    request_object->signal()->add_abort_algorithm([&vm, locally_aborted, request, controller, promise_capability_handle = JS::make_handle(*promise_capability), request_object_handle = JS::make_handle(*request_object), response_object_handle] {
         dbgln_if(WEB_FETCH_DEBUG, "Fetch: Request object signal's abort algorithm called");
 
         auto& promise_capability = *promise_capability_handle;

Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp

@@ -260,7 +260,7 @@ WebIDL::ExceptionOr<Optional<JS::NonnullGCPtr<PendingResponse>>> main_fetch(JS::
         request->current_url().set_scheme("https"sv);
     }
 
-    JS::SafeFunction<WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>>()> get_response = [&realm, &vm, &fetch_params, request]() mutable -> WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> {
+    JS::SafeFunction<WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>>()> get_response = [&realm, &vm, &fetch_params, request]() -> WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> {
         dbgln_if(WEB_FETCH_DEBUG, "Fetch: Running 'main fetch' get_response() function");
 
         // -> fetchParams’s preloaded response candidate is not null
@@ -333,7 +333,7 @@ WebIDL::ExceptionOr<Optional<JS::NonnullGCPtr<PendingResponse>>> main_fetch(JS::
 
             // 2. Let corsWithPreflightResponse be the result of running HTTP fetch given fetchParams and true.
             auto cors_with_preflight_response = TRY(http_fetch(realm, fetch_params, MakeCORSPreflight::Yes));
-            cors_with_preflight_response->when_loaded([returned_pending_response](JS::NonnullGCPtr<Infrastructure::Response> cors_with_preflight_response) mutable {
+            cors_with_preflight_response->when_loaded([returned_pending_response](JS::NonnullGCPtr<Infrastructure::Response> cors_with_preflight_response) {
                 dbgln_if(WEB_FETCH_DEBUG, "Fetch: Running 'main fetch' cors_with_preflight_response load callback");
                 // 3. If corsWithPreflightResponse is a network error, then clear cache entries using request.
                 if (cors_with_preflight_response->is_network_error()) {
@@ -368,7 +368,7 @@ WebIDL::ExceptionOr<Optional<JS::NonnullGCPtr<PendingResponse>>> main_fetch(JS::
     }
 
     // 10. If recursive is false, then run the remaining steps in parallel.
-    Platform::EventLoopPlugin::the().deferred_invoke([&realm, &vm, &fetch_params, request, response, get_response = move(get_response)]() mutable {
+    Platform::EventLoopPlugin::the().deferred_invoke([&realm, &vm, &fetch_params, request, response, get_response = move(get_response)] {
         // 11. If response is null, then set response to the result of running the steps corresponding to the first
         //     matching statement:
         auto pending_response = PendingResponse::create(vm, request, Infrastructure::Response::create(vm));
@@ -898,7 +898,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_fetch(JS::Realm& rea
                 // HTTP-redirect fetch given fetchParams and response.
                 response = Infrastructure::OpaqueRedirectFilteredResponse::create(vm, *actual_response);
                 if (request->mode() == Infrastructure::Request::Mode::Navigate) {
-                    fetch_params.controller()->set_next_manual_redirect_steps([&realm, &fetch_params, response]() mutable {
+                    fetch_params.controller()->set_next_manual_redirect_steps([&realm, &fetch_params, response] {
                         (void)http_redirect_fetch(realm, fetch_params, *response);
                     });
                 }
@@ -914,7 +914,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_fetch(JS::Realm& rea
         }
 
         if (inner_pending_response) {
-            inner_pending_response->when_loaded([returned_pending_response](JS::NonnullGCPtr<Infrastructure::Response> response) mutable {
+            inner_pending_response->when_loaded([returned_pending_response](JS::NonnullGCPtr<Infrastructure::Response> response) {
                 dbgln_if(WEB_FETCH_DEBUG, "Fetch: Running 'HTTP fetch' inner_pending_response load callback");
                 returned_pending_response->resolve(response);
             });
@@ -1465,7 +1465,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_network_or_cache_fet
             inner_pending_response = TRY_OR_IGNORE(http_network_or_cache_fetch(realm, fetch_params, IsAuthenticationFetch::Yes));
         }
 
-        inner_pending_response->when_loaded([&realm, &vm, &fetch_params, request, returned_pending_response, is_authentication_fetch, is_new_connection_fetch](JS::NonnullGCPtr<Infrastructure::Response> response) mutable {
+        inner_pending_response->when_loaded([&realm, &vm, &fetch_params, request, returned_pending_response, is_authentication_fetch, is_new_connection_fetch](JS::NonnullGCPtr<Infrastructure::Response> response) {
             dbgln_if(WEB_FETCH_DEBUG, "Fetch: Running 'HTTP network-or-cache fetch' inner_pending_response load callback");
             // 15. If response’s status is 407, then:
             if (response->status() == 407) {
@@ -1515,7 +1515,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_network_or_cache_fet
                 inner_pending_response = TRY_OR_IGNORE(http_network_or_cache_fetch(realm, fetch_params, is_authentication_fetch, IsNewConnectionFetch::Yes));
             }
 
-            inner_pending_response->when_loaded([returned_pending_response, is_authentication_fetch](JS::NonnullGCPtr<Infrastructure::Response> response) mutable {
+            inner_pending_response->when_loaded([returned_pending_response, is_authentication_fetch](JS::NonnullGCPtr<Infrastructure::Response> response) {
                 // 17. If isAuthenticationFetch is true, then create an authentication entry for request and the given
                 //     realm.
                 if (is_authentication_fetch == IsAuthenticationFetch::Yes) {
@@ -1595,7 +1595,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> nonstandard_resource_load
 
     ResourceLoader::the().load(
         load_request,
-        [&realm, &vm, request, pending_response](auto data, auto& response_headers, auto status_code) mutable {
+        [&realm, &vm, request, pending_response](auto data, auto& response_headers, auto status_code) {
             dbgln_if(WEB_FETCH_DEBUG, "Fetch: ResourceLoader load for '{}' complete", request->url());
             if constexpr (WEB_FETCH_DEBUG)
                 log_response(status_code, response_headers, data);
@@ -1610,7 +1610,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> nonstandard_resource_load
             // FIXME: Set response status message
             pending_response->resolve(response);
         },
-        [&vm, request, pending_response](auto& error, auto status_code) mutable {
+        [&vm, request, pending_response](auto& error, auto status_code) {
             dbgln_if(WEB_FETCH_DEBUG, "Fetch: ResourceLoader load for '{}' failed: {} (status {})", request->url(), error, status_code.value_or(0));
             auto response = Infrastructure::Response::create(vm);
             // FIXME: This is ugly, ResourceLoader should tell us.

Userland/Libraries/LibWeb/Fetch/Fetching/PendingResponse.cpp

@@ -56,7 +56,7 @@ void PendingResponse::run_callback() const
 {
     VERIFY(m_callback);
     VERIFY(m_response);
-    Platform::EventLoopPlugin::the().deferred_invoke([strong_this = JS::make_handle(const_cast<PendingResponse&>(*this))]() mutable {
+    Platform::EventLoopPlugin::the().deferred_invoke([strong_this = JS::make_handle(const_cast<PendingResponse&>(*this))] {
         strong_this->m_callback(*strong_this->m_response);
         strong_this->m_request->remove_pending_response({}, *strong_this.ptr());
     });

Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp

@@ -1142,7 +1142,7 @@ WebIDL::ExceptionOr<void> BrowsingContext::traverse_the_history(size_t entry_ind
     if (new_document->ready_state() == "complete"sv) {
         // then queue a global task on the DOM manipulation task source given newDocument's relevant global object to run the following steps:
 
-        queue_global_task(Task::Source::DOMManipulation, relevant_global_object(*new_document), [new_document]() mutable {
+        queue_global_task(Task::Source::DOMManipulation, relevant_global_object(*new_document), [new_document] {
             // 1. If newDocument's page showing flag is true, then abort these steps.
             if (new_document->page_showing())
                 return;
@@ -1211,7 +1211,7 @@ WebIDL::ExceptionOr<void> BrowsingContext::traverse_the_history(size_t entry_ind
     // 20. If hashChanged is true,
     if (hash_changed) {
         // then queue a global task on the DOM manipulation task source given newDocument's relevant global object
-        queue_global_task(Task::Source::DOMManipulation, relevant_global_object(*new_document), [new_document]() mutable {
+        queue_global_task(Task::Source::DOMManipulation, relevant_global_object(*new_document), [new_document] {
             // to fire an event named hashchange at newDocument's relevant global object,
             // using HashChangeEvent, with the oldURL attribute initialized to oldURL
             // and the newURL attribute initialized to newURL.
@@ -1330,7 +1330,7 @@ void BrowsingContext::set_system_visibility_state(VisibilityState visibility_sta
     // has changed to newState, it must queue a task on the user interaction task source to update
     // the visibility state of all the Document objects in the top-level browsing context's document family with newState.
     auto document_family = top_level_browsing_context().document_family();
-    queue_global_task(Task::Source::UserInteraction, Bindings::main_thread_vm().current_realm()->global_object(), [visibility_state, document_family = move(document_family)]() mutable {
+    queue_global_task(Task::Source::UserInteraction, Bindings::main_thread_vm().current_realm()->global_object(), [visibility_state, document_family = move(document_family)] {
         for (auto& document : document_family) {
             document->update_the_visibility_state(visibility_state);
         }

Userland/Libraries/LibWeb/HTML/FormAssociatedElement.cpp

@@ -103,7 +103,7 @@ void FormAssociatedElement::reset_form_owner()
     if (is_listed() && html_element.has_attribute(HTML::AttributeNames::form) && html_element.is_connected()) {
         // 1. If the first element in element's tree, in tree order, to have an ID that is identical to element's form content attribute's value, is a form element, then associate the element with that form element.
         auto form_value = html_element.attribute(HTML::AttributeNames::form);
-        html_element.root().for_each_in_inclusive_subtree_of_type<HTMLFormElement>([this, &form_value](HTMLFormElement& form_element) mutable {
+        html_element.root().for_each_in_inclusive_subtree_of_type<HTMLFormElement>([this, &form_value](HTMLFormElement& form_element) {
             if (form_element.attribute(HTML::AttributeNames::id) == form_value) {
                 set_form(&form_element);
                 return IterationDecision::Break;

Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp

@@ -534,7 +534,7 @@ void HTMLHyperlinkElementUtils::follow_the_hyperlink(Optional<String> hyperlink_
     // set to source.
     // FIXME: "navigate" means implementing the navigation algorithm here:
     //        https://html.spec.whatwg.org/multipage/browsing-the-web.html#navigate
-    hyperlink_element_utils_queue_an_element_task(Task::Source::DOMManipulation, [url_string, target]() mutable {
+    hyperlink_element_utils_queue_an_element_task(Task::Source::DOMManipulation, [url_string, target] {
         target->loader().load(url_string, FrameLoader::Type::Navigation);
     });
 }

Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp

@@ -123,7 +123,7 @@ void HTMLInputElement::set_files(JS::GCPtr<FileAPI::FileList> files)
 void HTMLInputElement::update_the_file_selection(JS::NonnullGCPtr<FileAPI::FileList> files)
 {
     // 1. Queue an element task on the user interaction task source given element and the following steps:
-    queue_an_element_task(Task::Source::UserInteraction, [this, files]() mutable {
+    queue_an_element_task(Task::Source::UserInteraction, [this, files] {
         // 1. Update element's selected files so that it represents the user's selection.
         this->set_files(files.ptr());
 

Userland/Libraries/LibWeb/HTML/MessagePort.cpp

@@ -88,7 +88,7 @@ void MessagePort::post_message(JS::Value message)
 
     // FIXME: This is an ad-hoc hack implementation instead, since we don't currently
     //        have serialization and deserialization of messages.
-    main_thread_event_loop().task_queue().add(HTML::Task::create(HTML::Task::Source::PostedMessage, nullptr, [target_port, message]() mutable {
+    main_thread_event_loop().task_queue().add(HTML::Task::create(HTML::Task::Source::PostedMessage, nullptr, [target_port, message] {
         MessageEventInit event_init {};
         event_init.data = message;
         event_init.origin = "<origin>";

Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp

@@ -250,7 +250,7 @@ void HTMLParser::the_end()
     }
 
     // 6. Queue a global task on the DOM manipulation task source given the Document's relevant global object to run the following substeps:
-    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, *m_document, [document = m_document]() mutable {
+    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, *m_document, [document = m_document] {
         // 1. Set the Document's load timing info's DOM content loaded event start time to the current high resolution time given the Document's relevant global object.
         document->load_timing_info().dom_content_loaded_event_start_time = HighResolutionTime::unsafe_shared_current_time();
 
@@ -279,7 +279,7 @@ void HTMLParser::the_end()
     });
 
     // 9. Queue a global task on the DOM manipulation task source given the Document's relevant global object to run the following steps:
-    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, *m_document, [document = m_document]() mutable {
+    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, *m_document, [document = m_document] {
         // 1. Update the current document readiness to "complete".
         document->update_readiness(HTML::DocumentReadyState::Complete);
 

Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp

@@ -228,7 +228,7 @@ void EnvironmentSettingsObject::notify_about_rejected_promises(Badge<EventLoop>)
     auto& global = global_object();
 
     // 5. Queue a global task on the DOM manipulation task source given global to run the following substep:
-    queue_global_task(Task::Source::DOMManipulation, global, [this, &global, list = move(list)]() mutable {
+    queue_global_task(Task::Source::DOMManipulation, global, [this, &global, list = move(list)] {
         // 1. For each promise p in list:
         for (auto promise : list) {
 

Userland/Libraries/LibWeb/HTML/Window.cpp

@@ -495,7 +495,7 @@ i32 Window::run_timer_initialization_steps(TimerHandler handler, i32 timeout, JS
     // 8. Assert: initiating script is not null, since this algorithm is always called from some script.
 
     // 9. Let task be a task that runs the following substeps:
-    JS::SafeFunction<void()> task = [this, handler = move(handler), timeout, arguments = move(arguments), repeat, id]() mutable {
+    JS::SafeFunction<void()> task = [this, handler = move(handler), timeout, arguments = move(arguments), repeat, id] {
         // 1. If id does not exist in global's map of active timers, then abort these steps.
         if (!m_timers.contains(id))
             return;
@@ -564,7 +564,7 @@ i32 Window::run_timer_initialization_steps(TimerHandler handler, i32 timeout, JS
 // https://html.spec.whatwg.org/multipage/imagebitmap-and-animations.html#run-the-animation-frame-callbacks
 i32 Window::request_animation_frame_impl(WebIDL::CallbackType& js_callback)
 {
-    return m_animation_frame_callback_driver.add([this, js_callback = JS::make_handle(js_callback)](auto) mutable {
+    return m_animation_frame_callback_driver.add([this, js_callback = JS::make_handle(js_callback)](auto) {
         // 3. Invoke callback, passing now as the only argument,
         auto result = WebIDL::invoke_callback(*js_callback, {}, JS::Value(performance().now()));
 
@@ -802,7 +802,7 @@ void Window::fire_a_page_transition_event(FlyString const& event_name, bool pers
 void Window::queue_microtask_impl(WebIDL::CallbackType& callback)
 {
     // The queueMicrotask(callback) method must queue a microtask to invoke callback,
-    HTML::queue_a_microtask(&associated_document(), [this, &callback]() mutable {
+    HTML::queue_a_microtask(&associated_document(), [this, &callback] {
         auto result = WebIDL::invoke_callback(callback, {});
         // and if callback throws an exception, report the exception.
         if (result.is_error())
@@ -906,7 +906,7 @@ WebIDL::ExceptionOr<void> Window::post_message_impl(JS::Value message, String co
 {
     // FIXME: This is an ad-hoc hack implementation instead, since we don't currently
     //        have serialization and deserialization of messages.
-    HTML::queue_global_task(HTML::Task::Source::PostedMessage, *this, [this, message]() mutable {
+    HTML::queue_global_task(HTML::Task::Source::PostedMessage, *this, [this, message] {
         HTML::MessageEventInit event_init {};
         event_init.data = message;
         event_init.origin = "<origin>";
@@ -961,7 +961,7 @@ void Window::start_an_idle_period()
 
     // 5. Queue a task on the queue associated with the idle-task task source,
     //    which performs the steps defined in the invoke idle callbacks algorithm with window and getDeadline as parameters.
-    HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this]() mutable {
+    HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this] {
         invoke_idle_callbacks();
     });
 }
@@ -985,7 +985,7 @@ void Window::invoke_idle_callbacks()
             HTML::report_exception(result, realm());
         // 4. If window's list of runnable idle callbacks is not empty, queue a task which performs the steps
         //    in the invoke idle callbacks algorithm with getDeadline and window as a parameters and return from this algorithm
-        HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this]() mutable {
+        HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this] {
             invoke_idle_callbacks();
         });
     }

Userland/Libraries/LibWeb/HTML/Worker.cpp

@@ -154,7 +154,7 @@ void Worker::run_a_worker(AK::URL& url, EnvironmentSettingsObject& outside_setti
 
             auto& event_loop = get_vm_event_loop(m_document->realm().vm());
 
-            event_loop.task_queue().add(HTML::Task::create(HTML::Task::Source::PostedMessage, nullptr, [this, message]() mutable {
+            event_loop.task_queue().add(HTML::Task::create(HTML::Task::Source::PostedMessage, nullptr, [this, message] {
                 MessageEventInit event_init {};
                 event_init.data = message;
                 event_init.origin = "<origin>";

Userland/Libraries/LibWeb/Loader/Resource.cpp

@@ -168,7 +168,7 @@ void ResourceClient::set_resource(Resource* resource)
         // This ensures that these callbacks always happen in a consistent way, instead of being invoked
         // synchronously in some cases, and asynchronously in others.
         if (resource->is_loaded() || resource->is_failed()) {
-            Platform::EventLoopPlugin::the().deferred_invoke([weak_this = make_weak_ptr(), strong_resource = NonnullRefPtr { *m_resource }]() mutable {
+            Platform::EventLoopPlugin::the().deferred_invoke([weak_this = make_weak_ptr(), strong_resource = NonnullRefPtr { *m_resource }] {
                 if (!weak_this)
                     return;
 

Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp

@@ -285,7 +285,7 @@ void ResourceLoader::load(LoadRequest& request, Function<void(ReadonlyBytes, Has
 
         if (timeout.has_value() && timeout.value() > 0) {
             auto timer = Platform::Timer::create_single_shot(timeout.value(), nullptr);
-            timer->on_timeout = [timer, protocol_request, timeout_callback = move(timeout_callback)]() mutable {
+            timer->on_timeout = [timer, protocol_request, timeout_callback = move(timeout_callback)] {
                 protocol_request->stop();
                 if (timeout_callback)
                     timeout_callback();

Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp

@@ -178,7 +178,7 @@ void XMLDocumentBuilder::document_end()
         (void)m_document.scripts_to_execute_when_parsing_has_finished().take_first();
     }
     // Queue a global task on the DOM manipulation task source given the Document's relevant global object to run the following substeps:
-    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, m_document, [document = &m_document]() mutable {
+    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, m_document, [document = &m_document] {
         // Set the Document's load timing info's DOM content loaded event start time to the current high resolution time given the Document's relevant global object.
         document->load_timing_info().dom_content_loaded_event_start_time = HighResolutionTime::unsafe_shared_current_time();
 
@@ -206,7 +206,7 @@ void XMLDocumentBuilder::document_end()
     });
 
     // Queue a global task on the DOM manipulation task source given the Document's relevant global object to run the following steps:
-    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, m_document, [document = &m_document]() mutable {
+    old_queue_global_task_with_document(HTML::Task::Source::DOMManipulation, m_document, [document = &m_document] {
         // Update the current document readiness to "complete".
         document->update_readiness(HTML::DocumentReadyState::Complete);
 

Userland/Services/SQLServer/SQLStatement.cpp

@@ -60,7 +60,7 @@ void SQLStatement::execute()
         return;
     }
 
-    deferred_invoke([this]() mutable {
+    deferred_invoke([this] {
         auto parse_result = parse();
         if (parse_result.is_error()) {
             report_error(parse_result.release_error());

Userland/Services/WebDriver/Session.cpp

@@ -36,7 +36,7 @@ ErrorOr<NonnullRefPtr<Core::LocalServer>> Session::create_server(String const& s
     auto server = TRY(Core::LocalServer::try_create());
     server->listen(socket_path);
 
-    server->on_accept = [this, promise](auto client_socket) mutable {
+    server->on_accept = [this, promise](auto client_socket) {
         auto maybe_connection = adopt_nonnull_ref_or_enomem(new (nothrow) WebContentConnection(move(client_socket), m_client, session_id()));
         if (maybe_connection.is_error()) {
             promise->resolve(maybe_connection.release_error());
@@ -49,7 +49,7 @@ ErrorOr<NonnullRefPtr<Core::LocalServer>> Session::create_server(String const& s
         promise->resolve({});
     };
 
-    server->on_accept_error = [promise](auto error) mutable {
+    server->on_accept_error = [promise](auto error) {
         promise->resolve(move(error));
     };
 

Userland/Services/WindowServer/ConnectionFromClient.cpp

@@ -234,7 +234,7 @@ void ConnectionFromClient::flash_menubar_menu(i32 window_id, i32 menu_id)
             m_flashed_menu_timer->stop();
         }
 
-        m_flashed_menu_timer = Core::Timer::create_single_shot(75, [weak_window = window.make_weak_ptr<Window>()]() mutable {
+        m_flashed_menu_timer = Core::Timer::create_single_shot(75, [weak_window = window.make_weak_ptr<Window>()] {
             if (!weak_window)
                 return;
             weak_window->menubar().flash_menu(nullptr);

Userland/Utilities/headless-browser.cpp

@@ -327,7 +327,7 @@ public:
             , m_socket(move(socket))
             , m_job(HTTP::Job::construct(move(request), *m_output_stream))
         {
-            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) mutable {
+            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) {
                 if (auto strong_this = weak_this.strong_ref()) {
                     strong_this->m_response_code = response_code;
                     for (auto& header : response_headers) {
@@ -335,8 +335,8 @@ public:
                     }
                 }
             };
-            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) mutable {
-                Core::deferred_invoke([weak_this, success]() mutable {
+            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) {
+                Core::deferred_invoke([weak_this, success] {
                     if (auto strong_this = weak_this.strong_ref()) {
                         ReadonlyBytes response_bytes { strong_this->m_output_stream->bytes().data(), strong_this->m_output_stream->offset() };
                         auto response_buffer = ByteBuffer::copy(response_bytes).release_value_but_fixme_should_propagate_errors();
@@ -406,7 +406,7 @@ public:
             , m_socket(move(socket))
             , m_job(HTTP::HttpsJob::construct(move(request), *m_output_stream))
         {
-            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) mutable {
+            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) {
                 if (auto strong_this = weak_this.strong_ref()) {
                     strong_this->m_response_code = response_code;
                     for (auto& header : response_headers) {
@@ -414,8 +414,8 @@ public:
                     }
                 }
             };
-            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) mutable {
-                Core::deferred_invoke([weak_this, success]() mutable {
+            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) {
+                Core::deferred_invoke([weak_this, success] {
                     if (auto strong_this = weak_this.strong_ref()) {
                         ReadonlyBytes response_bytes { strong_this->m_output_stream->bytes().data(), strong_this->m_output_stream->offset() };
                         auto response_buffer = ByteBuffer::copy(response_bytes).release_value_but_fixme_should_propagate_errors();
@@ -475,7 +475,7 @@ public:
             , m_socket(move(socket))
             , m_job(Gemini::Job::construct(move(request), *m_output_stream))
         {
-            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) mutable {
+            m_job->on_headers_received = [weak_this = make_weak_ptr()](auto& response_headers, auto response_code) {
                 if (auto strong_this = weak_this.strong_ref()) {
                     strong_this->m_response_code = response_code;
                     for (auto& header : response_headers) {
@@ -483,8 +483,8 @@ public:
                     }
                 }
             };
-            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) mutable {
-                Core::deferred_invoke([weak_this, success]() mutable {
+            m_job->on_finish = [weak_this = make_weak_ptr()](bool success) {
+                Core::deferred_invoke([weak_this, success] {
                     if (auto strong_this = weak_this.strong_ref()) {
                         ReadonlyBytes response_bytes { strong_this->m_output_stream->bytes().data(), strong_this->m_output_stream->offset() };
                         auto response_buffer = ByteBuffer::copy(response_bytes).release_value_but_fixme_should_propagate_errors();
@@ -717,7 +717,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     dbgln("Taking screenshot after {} seconds !", take_screenshot_after);
     auto timer = Core::Timer::create_single_shot(
         take_screenshot_after * 1000,
-        [page_client = move(page_client)]() mutable {
+        [page_client = move(page_client)] {
             // FIXME: Allow passing the output path as argument
             String output_file_path = "output.png";
             dbgln("Saving to {}", output_file_path);