Qt5 dependency on Kinetic - Cannot build with Qt4

[theobslhc]

rviz will not build with Qt4 on branch kinetic-devel :

.../rviz/src/rviz/visualization_frame.cpp:1253:66: error: ‘FindDirectChildrenOnly’ is not a member of ‘Qt’
   QList<QTabBar *> tab_bars = findChildren<QTabBar *>(QString(), Qt::FindDirectChildrenOnly);

Merged PR #1168 relies on Qt::FindDirectChildrenOnly to get a list of all QTabBar children of VisualizationFrame, which is a flag to QObject::findChild() that was introduced in Qt5.

See visualization_frame.cpp, line 1253 :

QList<QTabBar *> tab_bars = findChildren<QTabBar *>(QString(), Qt::FindDirectChildrenOnly);

Qt4 does not seem to provide an "easy" equivalent of this flag. The subject of reproducing its behaviour has been covered here, but proposed solutions rely on the children's object names, which I am not sure will be reliable in the context of rviz.

Your environment

• OS Version: e.g. Ubuntu 16.04
• ROS Distro: Kinetic
• RViz, Qt, OGRE, OpenGl version as printed by rviz:

  no build, Qt 4.8.7
  

[wjwwood]

Technically Kinetic requires Qt5:

http://www.ros.org/reps/rep-0003.html#kinetic-kame-may-2016-may-2021

Though we had tried to be friendly to Qt4 in that release, it's technically unsupported. So I can't say I'm surprised that it's broken.

[theobslhc]

@wjwwood thanks for your feedback. I had missed that detail.
I will try to investigate the issue myself and submit a PR if time allows, for the sake of Qt4-friendliness :)