Qt5 drops (q_)foreach in a future release
Quassel makes use of q_foreach (or rather Qt's foreach macro) multiple times in it's code. According to a note in the Qt documentation, "the usage of this macro is discouraged" since Qt 5.7 (http://doc.qt.io/qt-5/qtglobal.html#Q_FOREACH). The alternative to that is to use C++11's ranged-for loops (as also suggested in the documetation of Qt). Since Quassel requires C++11 for 0.13 onwards anyway, this does not break backwards compatibility to previous releases.
digitalcircuit suggested to handle this whilst doing the huge code cleanup planned for 0.13.