Avoid sending PART command for unjoined channels

fix #3205

src/bridge/bridge.cpp

@@ -359,8 +359,16 @@ void Bridge::leave_irc_channel(Iid&& iid, const std::string& status_message, con
 
   const auto resources = this->number_of_resources_in_chan(key);
   if (resources == 1)
+    {
+      // Do not send a PART message if we actually are not in that channel
+      // or if we already sent a PART but we are just waiting for the
+      // acknowledgment from the server
+      IrcChannel* channel = irc->get_channel(iid.get_local());
+      if (channel->joined && !channel->parting)
         {
           irc->send_part_command(iid.get_local(), status_message);
+          channel->parting = true;
+        }
       // Since there are no resources left in that channel, we don't
       // want to receive private messages using this room's JID
       this->remove_all_preferred_from_jid_of_room(iid.get_local());

src/irc/irc_channel.cpp

@@ -1,12 +1,6 @@
 #include <irc/irc_channel.hpp>
 #include <algorithm>
 
-IrcChannel::IrcChannel():
-  joined(false),
-  self(nullptr)
-{
-}
-
 void IrcChannel::set_self(const std::string& name)
 {
   this->self = std::make_unique<IrcUser>(name);

src/irc/irc_channel.hpp

@@ -14,16 +14,19 @@
 class IrcChannel
 {
 public:
-  explicit IrcChannel();
+  IrcChannel() = default;
 
   IrcChannel(const IrcChannel&) = delete;
   IrcChannel(IrcChannel&&) = delete;
   IrcChannel& operator=(const IrcChannel&) = delete;
   IrcChannel& operator=(IrcChannel&&) = delete;
 
-  bool joined;
-  std::string topic;
-  std::string topic_author;
+  bool joined{false};
+  // Set to true if we sent a PART but didn’t yet receive the PART ack from
+  // the server
+  bool parting{false};
+  std::string topic{};
+  std::string topic_author{};
   void set_self(const std::string& name);
   IrcUser* get_self() const;
   IrcUser* add_user(const std::string& name,
@@ -35,8 +38,8 @@ public:
   { return this->users; }
 
 protected:
-  std::unique_ptr<IrcUser> self;
-  std::vector<std::unique_ptr<IrcUser>> users;
+  std::unique_ptr<IrcUser> self{};
+  std::vector<std::unique_ptr<IrcUser>> users{};
 };
 
 /**