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QMainWindowLayout: de-pessimize ~QMainWindowToolBar

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As the code comment says, ~QMainWindowTabBar will removeOne(this) from
QMainWindowLayout::unusedTabBars. It doesn't assert that it was
included in it, or something special like that.

So we can optimize the whole thing by making sure that
~QMainWindowTabBar doesn't find anything to remove here, avoiding a
detach from the copy 'bars' and potentially also avoiding quadratic
behavior, as we delete the items in order.

Found by Coverity, but it only saw this as an optimization opportunity
because it doesn't understand that the copy is needed.

Amends 23357e59bb4dc54e76a237b290aa64a620db2ea1.

Pick-to: 6.9 6.8 6.5
Coverity-Id: 479705
Change-Id: I6c31e028c0c39813768e8c71076471b39bd8ef5a
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
This commit is contained in:
Marc Mutz 2025-04-06 14:32:07 +02:00 committed by Axel Spoerl
parent 7ce4a8a8c9
commit fb7670f193
1 changed files with 3 additions and 2 deletions
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5
src/widgets/widgets/qmainwindowlayout.cpp
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@ -2733,8 +2733,9 @@ QMainWindowLayout::~QMainWindowLayout()
#if QT_CONFIG(dockwidget) && QT_CONFIG(tabwidget)
// unusedTabBars contains unparented tab bars, which need to be removed manually.
// ~QMainWindowTabBar() removes the bar from unusedTabBars => call qDeleteAll() on a copy.
const auto bars = unusedTabBars;
// ~QMainWindowTabBar() attempts to remove the bar from unusedTabBars
// => move it out of the way first.
const auto bars = std::move(unusedTabBars);
qDeleteAll(bars);
#endif // QT_CONFIG(dockwidget) && QT_CONFIG(tabwidget)
}