KDirListerCache destroy comment in kcoredirlister.cpp

[Kevin Funk]

On Monday, 29 January 2018 11:32:56 CET René J.V. Bertin wrote:
> Hi,
> 
> Researching an issue I'm seeing (hang/crash on exit) I found the following
> vestigial out-commented code the KCoreDirListerCache ctor in
> kcoredirlister.cpp:

FYI: Note to the mailing list, before more precious developer time is being 
spent on this here:

There are two more follow-up posts, just a few more hours younger, related to 
this issue on qt-interest:
  http://lists.qt-project.org/pipermail/interest/2018-January/029182.html
  (rather unrelated, but is also hinting at said problem...)
  http://lists.qt-project.org/pipermail/interest/2018-January/029194.html
  (asks about help for debugging crashes during destruction of QRegExpEngine)

Regards,
Kevin

>     // Probably not needed in KF5 anymore:
>     // The use of KUrl::url() in ~DirItem (sendSignal) crashes if the static
> for QRegExpEngine got deleted already, // so we need to destroy the
> KCoreDirListerCache before that.
>     //qAddPostRoutine(kDirListerCache.destroy);
> 
> WHat's clear is that this no longer works: there is no `destroy` method in
> whatever kDirListerCache's real class is.
> 
> Git blame is of little help here; can anyone remember why the explicit
> pro-active delete was deemed unnecessary, and what the exact symptoms were
> when this was not done in KDE4?
> 
> FWIW, the crash (or hang) happens during QRegExpEngine take-down when I have
> used a KDE file dialog in a "pure Qt" application via a mechanism built on
> code taken from the plasma integration plugin. It does not happen in KF5
> applications like kate or kdialog. As far as I know those applications
> obtain the KDE file dialog from the platform plugin too. The difference
> must be in the order in which certain things are deleted during the global
> destruction phase, but which and how to restore the proper order. (The
> Audacious audioplayer had a similar issue on exit in its Qt5 version, which
> I traced to the QApplication instance being deleted via atexit; a lucky
> shot in the dark that makes a lot of sense in retrospect.)
> 
> Thanks for any pointers,
> R.


-- 
Kevin Funk | kfunk at kde.org | http://kfunk.org
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