As you can see by the sample, Im not doing anything special, not changing any
ownership, and not doing any individual deletes + deleteLaters with a
processEvents (The root cause of many a "double delete in my experience"), so
Im really stumped on this one.
Something in designer with the UI file is causing this.
Scott
From: Interest <interest-boun...@qt-project.org> On Behalf Of Axel Spoerl via
Interest
Sent: Thursday, March 2, 2023 10:09 PM
To: interest@qt-project.org
Subject: Re: [Interest] Weird assert, how to debug?
Hi Scott,
I can't make the reproducer crash on Qt 5.15.9 or on the latest dev (6.6).
The assertion happens in QWidget's destructor, when it wants to exit from the
focus list.
I can imagine two cases, how this assertion kicks in.
* The code path in the if statement right after the assertion has been
reached before:
if (d->focus_next != this) {
d->focus_next->d_func()->focus_prev = d->focus_prev;
d->focus_prev->d_func()->focus_next = d->focus_next;
d->focus_next = d->focus_prev = nullptr;
}
=> An already deleted widget is deleted a second time.
* Focus chain has changed without events having been processed, so the
destroyed widget doesn't know about it.
Happens in the debugger (e.g. Qt Creator) sometimes, because debugging output
is a notirious focus thief.
Option 2 seems more likely to me, since the assertion doesn't shout in release
builds.
Updating to the latest Qt Creator version may help. If it doesn't please file a
bugreport in https://bugreports.qt.io,
upload the reproducer, specify the Qt and (Qt Creator if used for debugging)
versions used.
Cheers
Axel
________________________________
Von: Interest
<interest-boun...@qt-project.org<mailto:interest-boun...@qt-project.org>> im
Auftrag von Scott Bloom <sc...@towel42.com<mailto:sc...@towel42.com>>
Gesendet: Freitag, 3. März 2023 01:37
An: interest@qt-project.org<mailto:interest@qt-project.org>
<interest@qt-project.org<mailto:interest@qt-project.org>>
Betreff: [Interest] Weird assert, how to debug?
Im getting an assertion in qwidget.cpp
"d->focus_prev->d_func()->focus_next == this" in Qwidget.cpp line 1443 (Qt
5.15.10)
I realize the response is going to be, create a minimal example, I created a
repo on github with it, it's a simple cmake based project. Any help figuring
this out would be appreciated.
The application has a QApplication and a QDialog derived dialog. The dialog
has a tabwidget and a dialogbutton box.
The assertion gets thrown when the dialog is destroyed.
https://github.com/towel42-com/TestFocusAssert
This happens on Windows, I don't have a linux box setup right now to test on
linux.
Thanks
Scott
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