Room::usersAtEventId(): switch from QMultiHash to QHash of QSets

While slightly more complex for updating, this allows COW to kick in in
the read accessor; using QSet instead of QList also provides better
consistency guarantees. For QML both are converted to an Array-like
collection since Qt 5.15; Qt 5.12 turns QSet<> in a QVariantList,
according to the documentation, which is quite reasonable too.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/room.h b/lib/room.h
index cdbfe58f..fa7b6e6d 100644
--- a/lib/room.h
+++ b/lib/room.h
@@ -364,7 +364,7 @@ public:
     rev_iter_t readMarker(const User* user) const;
     rev_iter_t readMarker() const;
     QString readMarkerEventId() const;
-    QList<User*> usersAtEventId(const QString& eventId);
+    QSet<User*> usersAtEventId(const QString& eventId);
     /**
      * \brief Mark the event with uptoEventId as read
      *