QAbstractItemDelegate: tolerate that editor gets reparented

An item delegate might override destroyEditor to merely reparent the
existing editor out of the item view for later reuse, rather than
actually destroying the editor.

As of d0dffdfc012574da4a75241097b667d09bb39ba2, the code calling
closeEditor() - which calls destroyEditor - might explicitly set focus
back to the item view parent of the editor. This needs to handle that
the parent of the editor might no longer be valid after the closeEditor
call returns, and rather store the old parent widget explicitly.

Add a test case that segfaults with nullptr access without the fix.

Fixes: QTBUG-105231
Pick-to: 6.4 6.3 6.2
Change-Id: I04a355673823c4941865f7a575864e991ceeb5f0
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/widgets/itemviews/qabstractitemdelegate.cpp b/src/widgets/itemviews/qabstractitemdelegate.cpp
index c6161a4680..73af3b6b1d 100644
--- a/src/widgets/itemviews/qabstractitemdelegate.cpp
+++ b/src/widgets/itemviews/qabstractitemdelegate.cpp
@@ -480,12 +480,13 @@ bool QAbstractItemDelegatePrivate::editorEventFilter(QObject *object, QEvent *ev
             // If the application loses focus while editing, then the focus needs to go back
             // to the itemview when the editor closes. This ensures that when the application
             // is active again it will have the focus on the itemview as expected.
+            QWidget *editorParent = editor->parentWidget();
             const bool manuallyFixFocus = (event->type() == QEvent::FocusOut) && !editor->hasFocus() &&
-                    editor->parentWidget() &&
+                    editorParent &&
                     (static_cast<QFocusEvent *>(event)->reason() == Qt::ActiveWindowFocusReason);
             emit q->closeEditor(editor, QAbstractItemDelegate::NoHint);
             if (manuallyFixFocus)
-                editor->parentWidget()->setFocus();
+                editorParent->setFocus();
         }
 #ifndef QT_NO_SHORTCUT
     } else if (event->type() == QEvent::ShortcutOverride) {