Fix members dropdown and mention autocomplete.

Fixes #7345.

Telegram/SourceFiles/apiwrap.cpp

@@ -1503,7 +1503,8 @@ void ApiWrap::applyLastParticipantsList(
 	channel->mgInfo->lastAdmins.clear();
 	channel->mgInfo->lastRestricted.clear();
 	channel->mgInfo->lastParticipants.clear();
-	channel->mgInfo->lastParticipantsStatus = MegagroupInfo::LastParticipantsUpToDate;
+	channel->mgInfo->lastParticipantsStatus = MegagroupInfo::LastParticipantsUpToDate
+		| MegagroupInfo::LastParticipantsOnceReceived;
 
 	auto botStatus = channel->mgInfo->botStatus;
 	const auto emptyAdminRights = MTP_chatAdminRights(MTP_flags(0));

Telegram/SourceFiles/chat_helpers/field_autocomplete.cpp

@@ -206,8 +206,7 @@ void FieldAutocomplete::updateFiltered(bool resetScroll) {
 		if (_chat) {
 			maxListSize += (_chat->participants.empty() ? _chat->lastAuthors.size() : _chat->participants.size());
 		} else if (_channel && _channel->isMegagroup()) {
-			if (_channel->mgInfo->lastParticipants.empty() || _channel->lastParticipantsCountOutdated()) {
-			} else {
+			if (!_channel->lastParticipantsRequestNeeded()) {
 				maxListSize += _channel->mgInfo->lastParticipants.size();
 			}
 		}
@@ -274,7 +273,7 @@ void FieldAutocomplete::updateFiltered(bool resetScroll) {
 			}
 		} else if (_channel && _channel->isMegagroup()) {
 			QMultiMap<int32, UserData*> ordered;
-			if (_channel->mgInfo->lastParticipants.empty() || _channel->lastParticipantsCountOutdated()) {
+			if (_channel->lastParticipantsRequestNeeded()) {
 				Auth().api().requestLastParticipants(_channel);
 			} else {
 				mrows.reserve(mrows.size() + _channel->mgInfo->lastParticipants.size());

Telegram/SourceFiles/data/data_channel.cpp

@@ -340,6 +340,20 @@ bool ChannelData::isGroupAdmin(not_null<UserData*> user) const {
 	return false;
 }
 
+bool ChannelData::lastParticipantsRequestNeeded() const {
+	if (!mgInfo) {
+		return false;
+	} else if (mgInfo->lastParticipantsCount == membersCount()) {
+		mgInfo->lastParticipantsStatus
+			&= ~MegagroupInfo::LastParticipantsCountOutdated;
+	}
+	return mgInfo->lastParticipants.empty()
+		|| !(mgInfo->lastParticipantsStatus
+			& MegagroupInfo::LastParticipantsOnceReceived)
+		|| (mgInfo->lastParticipantsStatus
+			& MegagroupInfo::LastParticipantsCountOutdated);
+}
+
 auto ChannelData::unavailableReasons() const
 -> const std::vector<Data::UnavailableReason> & {
 	return _unavailableReasons;

Telegram/SourceFiles/data/data_channel.h

@@ -73,6 +73,7 @@ public:
 
 	enum LastParticipantsStatus {
 		LastParticipantsUpToDate       = 0x00,
+		LastParticipantsOnceReceived   = 0x01,
 		LastParticipantsCountOutdated  = 0x02,
 	};
 	mutable int lastParticipantsStatus = LastParticipantsUpToDate;
@@ -219,20 +220,7 @@ public:
 	void markForbidden();
 
 	[[nodiscard]] bool isGroupAdmin(not_null<UserData*> user) const;
-
-	[[nodiscard]] bool lastParticipantsCountOutdated() const {
-		if (!mgInfo
-			|| !(mgInfo->lastParticipantsStatus
-				& MegagroupInfo::LastParticipantsCountOutdated)) {
-			return false;
-		}
-		if (mgInfo->lastParticipantsCount == membersCount()) {
-			mgInfo->lastParticipantsStatus
-				&= ~MegagroupInfo::LastParticipantsCountOutdated;
-			return false;
-		}
-		return true;
-	}
+	[[nodiscard]] bool lastParticipantsRequestNeeded() const;
 	[[nodiscard]] bool isMegagroup() const {
 		return flags() & MTPDchannel::Flag::f_megagroup;
 	}

Telegram/SourceFiles/history/view/history_view_top_bar_widget.cpp

@@ -848,7 +848,7 @@ void TopBarWidget::updateOnlineDisplay() {
 		}
 	} else if (const auto channel = _activeChat.peer()->asChannel()) {
 		if (channel->isMegagroup() && channel->membersCount() > 0 && channel->membersCount() <= Global::ChatSizeMax()) {
-			if (channel->mgInfo->lastParticipants.empty() || channel->lastParticipantsCountOutdated()) {
+			if (channel->lastParticipantsRequestNeeded()) {
 				session().api().requestLastParticipants(channel);
 			}
 			const auto self = session().user();

Telegram/SourceFiles/profile/profile_block_group_members.cpp

@@ -192,7 +192,7 @@ void GroupMembersWidget::refreshMembers() {
 		fillChatMembers(chat);
 	} else if (const auto megagroup = peer()->asMegagroup()) {
 		auto &megagroupInfo = megagroup->mgInfo;
-		if (megagroupInfo->lastParticipants.empty() || megagroup->lastParticipantsCountOutdated()) {
+		if (megagroup->lastParticipantsRequestNeeded()) {
 			Auth().api().requestLastParticipants(megagroup);
 		}
 		fillMegagroupMembers(megagroup);