Fix warnings in examples

examples/media_downloader.cpp

@@ -150,7 +150,7 @@ message_handler(const mtx::responses::Messages &res, RequestErr err)
                 return;
         }
 
-        for (const auto msg : res.chunk)
+        for (const auto& msg : res.chunk)
                 print_message(msg);
 
         if (res.chunk.empty()) {

examples/online_backup_exporter.cpp

@@ -96,7 +96,6 @@ login_handler(const mtx::responses::Login &res, RequestErr err)
                                       if (secret.encrypted.size() != 1) {
                                               cerr << "Only one encryption key for backup "
                                                       "supported. Aborting.\n";
-                                              return;
                                               client->logout(
                                                 [](mtx::responses::Logout, RequestErr) {});
                                               return;

examples/room_feed.cpp

@@ -96,8 +96,8 @@ sync_handler(const mtx::responses::Sync &res, RequestErr err)
                 return;
         }
 
-        for (const auto room : res.rooms.join) {
-                for (const auto msg : room.second.timeline.events)
+        for (const auto& room : res.rooms.join) {
+                for (const auto& msg : room.second.timeline.events)
                         print_message(msg);
         }
 

examples/simple_bot.cpp

@@ -83,7 +83,7 @@ get_sender(const TimelineEvent &event)
 void
 parse_messages(const mtx::responses::Sync &res, bool parse_repeat_cmd = false)
 {
-        for (const auto room : res.rooms.invite) {
+        for (const auto& room : res.rooms.invite) {
                 auto room_id = room.first;
 
                 printf("joining room %s\n", room_id.c_str());
@@ -114,7 +114,7 @@ parse_messages(const mtx::responses::Sync &res, bool parse_repeat_cmd = false)
         if (!parse_repeat_cmd)
                 return;
 
-        for (const auto room : res.rooms.join) {
+        for (const auto& room : res.rooms.join) {
                 const std::string repeat_cmd = "!repeat";
                 const std::string room_id    = room.first;