Always use "must be non-empty".

td/telegram/BotMenuButton.cpp

@@ -133,7 +133,7 @@ void set_menu_button(Td *td, UserId user_id, td_api::object_ptr<td_api::botMenuB
     input_bot_menu_button = telegram_api::make_object<telegram_api::botMenuButtonCommands>();
   } else if (menu_button->text_.empty()) {
     if (menu_button->url_ != "default") {
-      return promise.set_error(Status::Error(400, "Menu button text can't be empty"));
+      return promise.set_error(Status::Error(400, "Menu button text must be non-empty"));
     }
     input_bot_menu_button = telegram_api::make_object<telegram_api::botMenuButtonDefault>();
   } else {

td/telegram/InlineQueriesManager.cpp

@@ -346,7 +346,7 @@ Result<tl_object_ptr<telegram_api::InputBotInlineMessage>> InlineQueriesManager:
     tl_object_ptr<td_api::InputMessageContent> &&input_message_content,
     tl_object_ptr<td_api::ReplyMarkup> &&reply_markup_ptr, int32 allowed_media_content_id) const {
   if (input_message_content == nullptr) {
-    return Status::Error(400, "Inline message can't be empty");
+    return Status::Error(400, "Inline message must be non-empty");
   }
   TRY_RESULT(reply_markup, get_reply_markup(std::move(reply_markup_ptr), true, true, false, true));
   auto input_reply_markup = get_input_reply_markup(td_->contacts_manager_.get(), reply_markup);

td/telegram/MessageContent.cpp

@@ -2794,7 +2794,7 @@ bool can_forward_message_content(const MessageContent *content) {
   auto content_type = content->get_type();
   if (content_type == MessageContentType::Text) {
     auto *text = static_cast<const MessageText *>(content);
-    return !is_empty_string(text->text.text);  // text can't be empty in the new message
+    return !is_empty_string(text->text.text);  // text must be non-empty in the new message
   }
   if (content_type == MessageContentType::Poll) {
     auto *poll = static_cast<const MessagePoll *>(content);

td/telegram/MessagesManager.cpp

@@ -20696,7 +20696,7 @@ DialogId MessagesManager::create_new_group_chat(const vector<UserId> &user_ids,
 
   auto new_title = clean_name(title, MAX_TITLE_LENGTH);
   if (new_title.empty()) {
-    promise.set_error(Status::Error(400, "Title can't be empty"));
+    promise.set_error(Status::Error(400, "Title must be non-empty"));
     return DialogId();
   }
 
@@ -20744,7 +20744,7 @@ DialogId MessagesManager::create_new_channel_chat(const string &title, bool is_m
 
   auto new_title = clean_name(title, MAX_TITLE_LENGTH);
   if (new_title.empty()) {
-    promise.set_error(Status::Error(400, "Title can't be empty"));
+    promise.set_error(Status::Error(400, "Title must be non-empty"));
     return DialogId();
   }
 
@@ -33748,7 +33748,7 @@ void MessagesManager::set_dialog_title(DialogId dialog_id, const string &title,
 
   auto new_title = clean_name(title, MAX_TITLE_LENGTH);
   if (new_title.empty()) {
-    return promise.set_error(Status::Error(400, "Title can't be empty"));
+    return promise.set_error(Status::Error(400, "Title must be non-empty"));
   }
 
   switch (dialog_id.get_type()) {

td/telegram/PhoneNumberManager.cpp

@@ -45,7 +45,7 @@ void PhoneNumberManager::send_new_send_code_query(uint64 query_id, const telegra
 
 void PhoneNumberManager::set_phone_number(uint64 query_id, string phone_number, Settings settings) {
   if (phone_number.empty()) {
-    return on_query_error(query_id, Status::Error(400, "Phone number can't be empty"));
+    return on_query_error(query_id, Status::Error(400, "Phone number must be non-empty"));
   }
 
   switch (type_) {
@@ -64,10 +64,10 @@ void PhoneNumberManager::set_phone_number(uint64 query_id, string phone_number,
 void PhoneNumberManager::set_phone_number_and_hash(uint64 query_id, string hash, string phone_number,
                                                    Settings settings) {
   if (phone_number.empty()) {
-    return on_query_error(query_id, Status::Error(400, "Phone number can't be empty"));
+    return on_query_error(query_id, Status::Error(400, "Phone number must be non-empty"));
   }
   if (hash.empty()) {
-    return on_query_error(query_id, Status::Error(400, "Hash can't be empty"));
+    return on_query_error(query_id, Status::Error(400, "Hash must be non-empty"));
   }
 
   switch (type_) {

td/telegram/ReplyMarkup.cpp

@@ -500,7 +500,7 @@ static Result<InlineKeyboardButton> get_inline_keyboard_button(tl_object_ptr<td_
   current_button.text = std::move(button->text_);
 
   if (button->type_ == nullptr) {
-    return Status::Error(400, "Inline keyboard button type can't be empty");
+    return Status::Error(400, "Inline keyboard button type must be non-empty");
   }
 
   int32 button_type_id = button->type_->get_id();

td/telegram/StickersManager.cpp

@@ -6995,7 +6995,7 @@ tl_object_ptr<telegram_api::inputStickerSetItem> StickersManager::get_input_stic
 void StickersManager::get_suggested_sticker_set_name(string title, Promise<string> &&promise) {
   title = strip_empty_characters(title, MAX_STICKER_SET_TITLE_LENGTH);
   if (title.empty()) {
-    return promise.set_error(Status::Error(400, "Sticker set title can't be empty"));
+    return promise.set_error(Status::Error(400, "Sticker set title must be non-empty"));
   }
 
   td_->create_handler<SuggestStickerSetShortNameQuery>(std::move(promise))->send(title);
@@ -7052,12 +7052,12 @@ void StickersManager::create_new_sticker_set(UserId user_id, string title, strin
 
   title = strip_empty_characters(title, MAX_STICKER_SET_TITLE_LENGTH);
   if (title.empty()) {
-    return promise.set_error(Status::Error(400, "Sticker set title can't be empty"));
+    return promise.set_error(Status::Error(400, "Sticker set title must be non-empty"));
   }
 
   short_name = strip_empty_characters(short_name, MAX_STICKER_SET_SHORT_NAME_LENGTH);
   if (short_name.empty()) {
-    return promise.set_error(Status::Error(400, "Sticker set name can't be empty"));
+    return promise.set_error(Status::Error(400, "Sticker set name must be non-empty"));
   }
 
   if (stickers.empty()) {
@@ -7292,7 +7292,7 @@ void StickersManager::add_sticker_to_set(UserId user_id, string short_name,
 
   short_name = clean_username(strip_empty_characters(short_name, MAX_STICKER_SET_SHORT_NAME_LENGTH));
   if (short_name.empty()) {
-    return promise.set_error(Status::Error(400, "Sticker set name can't be empty"));
+    return promise.set_error(Status::Error(400, "Sticker set name must be non-empty"));
   }
 
   const StickerSet *sticker_set = get_sticker_set(short_name_to_sticker_set_id_.get(short_name));
@@ -7386,7 +7386,7 @@ void StickersManager::set_sticker_set_thumbnail(UserId user_id, string short_nam
 
   short_name = clean_username(strip_empty_characters(short_name, MAX_STICKER_SET_SHORT_NAME_LENGTH));
   if (short_name.empty()) {
-    return promise.set_error(Status::Error(400, "Sticker set name can't be empty"));
+    return promise.set_error(Status::Error(400, "Sticker set name must be non-empty"));
   }
 
   const StickerSet *sticker_set = get_sticker_set(short_name_to_sticker_set_id_.get(short_name));

td/telegram/files/FileManager.cpp

@@ -2913,7 +2913,7 @@ Result<FileId> FileManager::from_persistent_id(CSlice persistent_id, FileType fi
   }
   auto binary = r_binary.move_as_ok();
   if (binary.empty()) {
-    return Status::Error(400, "Remote file identifier can't be empty");
+    return Status::Error(400, "Remote file identifier must be non-empty");
   }
   if (binary.back() == FileNode::PERSISTENT_ID_VERSION_OLD) {
     return from_persistent_id_v2(binary, file_type);

tdutils/td/utils/FileLog.cpp

@@ -18,7 +18,7 @@ namespace td {
 
 Status FileLog::init(string path, int64 rotate_threshold, bool redirect_stderr) {
   if (path.empty()) {
-    return Status::Error("Log file path can't be empty");
+    return Status::Error("Log file path must be non-empty");
   }
   if (path == path_) {
     set_rotate_threshold(rotate_threshold);