LibCore+Everywhere: Remove ArgsParser::add*(char const*&)

This is not guaranteed to always work correctly as ArgsParser deals in
StringViews and might have a non-properly-null-terminated string as a
value. As a bonus, using StringView (and DeprecatedString where
necessary) leads to nicer looking code too :^)

Userland/Applications/FontEditor/main.cpp

@@ -28,7 +28,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     Config::pledge_domain("FontEditor");
     TRY(Core::System::pledge("stdio recvfd sendfd thread rpath cpath wpath"));
 
-    char const* path = nullptr;
+    StringView path;
     Core::ArgsParser args_parser;
     args_parser.add_positional_argument(path, "The font file for editing.", "file", Core::ArgsParser::Required::No);
     args_parser.parse(arguments);
@@ -42,7 +42,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto font_editor = TRY(window->set_main_widget<FontEditor::MainWidget>());
     TRY(font_editor->initialize_menubar(*window));
 
-    if (path) {
+    if (!path.is_empty()) {
         TRY(font_editor->open_file(path));
     } else {
         auto mutable_font = TRY(TRY(Gfx::BitmapFont::try_load_from_file("/res/fonts/KaticaRegular10.font"))->unmasked_character_set());

Userland/Applications/ImageViewer/main.cpp

@@ -51,7 +51,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto app_icon = GUI::Icon::default_icon("filetype-image"sv);
 
-    char const* path = nullptr;
+    StringView path;
     Core::ArgsParser args_parser;
     args_parser.add_positional_argument(path, "The image file to be displayed.", "file", Core::ArgsParser::Required::No);
     args_parser.parse(arguments);
@@ -68,7 +68,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto main_toolbar = TRY(toolbar_container->try_add<GUI::Toolbar>());
 
     auto widget = TRY(root_widget->try_add<ViewWidget>());
-    if (path) {
+    if (!path.is_empty()) {
         widget->set_path(path);
     }
     widget->on_scale_change = [&](float scale) {

Userland/Applications/PDFViewer/main.cpp

@@ -18,7 +18,7 @@
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
-    char const* file_path = nullptr;
+    StringView file_path;
     Core::ArgsParser args_parser;
     args_parser.add_positional_argument(file_path, "PDF file to open", "path", Core::ArgsParser::Required::No);
     args_parser.parse(arguments);
@@ -45,7 +45,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->show();
     window->set_icon(app_icon.bitmap_for_size(16));
 
-    if (file_path) {
+    if (!file_path.is_empty()) {
         auto response = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, file_path);
         if (response.is_error())
             return 1;

Userland/Applications/PixelPaint/main.cpp

@@ -26,7 +26,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto app = TRY(GUI::Application::try_create(arguments));
     Config::pledge_domain("PixelPaint");
 
-    char const* image_file = nullptr;
+    StringView image_file;
     Core::ArgsParser args_parser;
     args_parser.add_positional_argument(image_file, "Image file to open", "path", Core::ArgsParser::Required::No);
     args_parser.parse(arguments);
@@ -72,7 +72,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     window->show();
 
-    if (image_file) {
+    if (!image_file.is_empty()) {
         auto response = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, image_file);
         if (response.is_error())
             return 1;

Userland/Applications/Spreadsheet/main.cpp

@@ -26,15 +26,15 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto app = TRY(GUI::Application::try_create(arguments));
 
-    char const* filename = nullptr;
+    StringView filename;
 
     Core::ArgsParser args_parser;
     args_parser.add_positional_argument(filename, "File to read from", "file", Core::ArgsParser::Required::No);
 
     args_parser.parse(arguments);
 
-    if (filename) {
-        if (!Core::DeprecatedFile::exists({ filename, strlen(filename) }) || Core::DeprecatedFile::is_directory(filename)) {
+    if (!filename.is_empty()) {
+        if (!Core::DeprecatedFile::exists(filename) || Core::DeprecatedFile::is_directory(filename)) {
             warnln("File does not exist or is a directory: {}", filename);
             return 1;
         }
@@ -51,7 +51,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->resize(640, 480);
     window->set_icon(app_icon.bitmap_for_size(16));
 
-    auto spreadsheet_widget = TRY(window->set_main_widget<Spreadsheet::SpreadsheetWidget>(*window, NonnullRefPtrVector<Spreadsheet::Sheet> {}, filename == nullptr));
+    auto spreadsheet_widget = TRY(window->set_main_widget<Spreadsheet::SpreadsheetWidget>(*window, NonnullRefPtrVector<Spreadsheet::Sheet> {}, filename.is_empty()));
 
     spreadsheet_widget->initialize_menubar(*window);
     spreadsheet_widget->update_window_title();
@@ -64,7 +64,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     window->show();
 
-    if (filename) {
+    if (!filename.is_empty()) {
         auto file = TRY(FileSystemAccessClient::Client::the().request_file_read_only_approved(window, filename));
         spreadsheet_widget->load_file(file.filename(), file.stream());
     }

Userland/Applications/Terminal/main.cpp

@@ -251,7 +251,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     Config::pledge_domain("Terminal");
 
-    char const* command_to_execute = nullptr;
+    StringView command_to_execute;
     bool keep_open = false;
 
     Core::ArgsParser args_parser;
@@ -260,7 +260,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     args_parser.parse(arguments);
 
-    if (keep_open && !command_to_execute) {
+    if (keep_open && command_to_execute.is_empty()) {
         warnln("Option -k can only be used in combination with -e.");
         return 1;
     }
@@ -273,7 +273,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
     if (shell_pid == 0) {
         close(ptm_fd);
-        if (command_to_execute)
+        if (!command_to_execute.is_empty())
             TRY(run_command(command_to_execute, keep_open));
         else
             TRY(run_command(Config::read_string("Terminal"sv, "Startup"sv, "Command"sv, ""sv), false));

Userland/Applications/TextEditor/main.cpp

@@ -27,7 +27,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     app->set_config_domain(TRY("TextEditor"_string));
 
     auto preview_mode = "auto"sv;
-    char const* file_to_edit = nullptr;
+    StringView file_to_edit;
     Core::ArgsParser parser;
     parser.add_option(preview_mode, "Preview mode, one of 'none', 'html', 'markdown', 'auto'", "preview-mode", '\0', "mode");
     parser.add_positional_argument(file_to_edit, "File to edit, with optional starting line and column number", "file[:line[:column]]", Core::ArgsParser::Required::No);
@@ -73,8 +73,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->show();
     window->set_icon(app_icon.bitmap_for_size(16));
 
-    if (file_to_edit) {
-        auto filename = TRY(String::from_utf8(StringView(file_to_edit, strlen(file_to_edit))));
+    if (!file_to_edit.is_empty()) {
+        auto filename = TRY(String::from_utf8(file_to_edit));
         FileArgument parsed_argument(filename);
         auto response = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, parsed_argument.filename().to_deprecated_string());