Review Request 122184: Remove seemingly outdated hack deleting the currently used QStyle at teardown

[Hugo Pereira Da Costa]

> On Jan. 21, 2015, 3:38 p.m., Hugo Pereira Da Costa wrote:
> > the delete call was introduces by D. Faure, at 2ffe20e1bfe93c921c5372b4d21447b1de308d4b
> > with log message:
> > 
> > Fix crash on exit in all QCommandLineParser-based programs.
> >     
> >     Example: kioclient5 ls  (= a syntax error).
> >     
> >     The issue is that ::exit(1) is called, so ~QGuiApplication isn't called
> >     (so the style isn't deleted), but global static objects are deleted,
> >     which deletes the style-plugin-factory, which unloads the style plugin.
> >     
> >     The crash happened because "AppEventFilter" in oxygen would still be
> >     installed as an app event filter, but the plugin was unloaded, so any
> >     calls to it would crash.
> >     
> > can you double-check ?
> > I'll add it to the review.
> 
> Hugo Pereira Da Costa wrote:
>     in fact, you should add +him+ (not 'it', sorry), because it seems I can't.
> 
> David Edmundson wrote:
>     "kioclient5 ls" doesn't crash here.
>     
>     The other option is in OxygenStylePlugin::create I put in a
>     connect(this, deleted(), theStyle, deleteLater());

yep. Here neither. Maybe David can comment further.


- Hugo


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On Jan. 21, 2015, 4:15 p.m., David Edmundson wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/122184/
> -----------------------------------------------------------
> 
> (Updated Jan. 21, 2015, 4:15 p.m.)
> 
> 
> Review request for Plasma, David Faure and Hugo Pereira Da Costa.
> 
> 
> Repository: oxygen
> 
> 
> Description
> -------
> 
> According to the comment we need to delete the qstyle object before the
> plugin if the application exits with exit(). A small test showed this is
> no longer the case.
> 
> More importantly this patch fixes a crash we see when styles were switched at
> runtime and the app uses exit().
> 
> Because Breeze has a similar delete line the first would run deleting
> the style object but leaving a dangling pointer, the second would run
> and crash.
> 
> Even if they only deleted their own style, both need to check the active style which means the second one is always accessing a dangling pointer.
> 
> ----
> 
> A similar approach needs to go into Breeze too. I shall copy that if this gets in.
> 
> 
> Diffs
> -----
> 
>   kstyle/oxygenstyleplugin.cpp 409ec13 
> 
> Diff: https://git.reviewboard.kde.org/r/122184/diff/
> 
> 
> Testing
> -------
> 
> Wrote a unit test that calls exit(0) on button press. This used to crash if we changed theme and then pressed the button. Now it no longer crashes ever.
> 
> Checked that kglobalaccel5 no longer crashes on exit after changing Breeze->Oxygen and does not crash after changing from Oxygen->Breeze
> 
> 
> Thanks,
> 
> David Edmundson
> 
>

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