Sync behavior and documentation of QFoo::setItemDelegate()

QComboBox::setItemDelegate() does delete the old delegate which is in
constrast to all other setItemDelegate() functions which is quite
confusing. Sync in by *not* deleting the delegate in
QComboBox::setItemDelegate() and adjust the documentation to explicitly
state that the ownership is *not* passed to the affected classes.

[ChangeLog][QtWidgets][QComboBox] QComobBox::setItemDelegates no longer
deletes the previous delegate set.

Fixes: QTBUG-72483
Change-Id: I89c8e53903e7c9924a980c57b83ce40f5866e6ae
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/widgets/widgets/qcombobox.cpp b/src/widgets/widgets/qcombobox.cpp
index d786c7ff83..785de35090 100644
--- a/src/widgets/widgets/qcombobox.cpp
+++ b/src/widgets/widgets/qcombobox.cpp
@@ -2096,6 +2096,9 @@ QAbstractItemDelegate *QComboBox::itemDelegate() const
     Sets the item \a delegate for the popup list view.
     The combobox takes ownership of the delegate.
 
+    Any existing delegate will be removed, but not deleted. QComboBox
+    does not take ownership of \a delegate.
+
     \warning You should not share the same instance of a delegate between comboboxes,
     widget mappers or views. Doing so can cause incorrect or unintuitive editing behavior
     since each view connected to a given delegate may receive the
@@ -2110,7 +2113,6 @@ void QComboBox::setItemDelegate(QAbstractItemDelegate *delegate)
         qWarning("QComboBox::setItemDelegate: cannot set a 0 delegate");
         return;
     }
-    delete view()->itemDelegate();
     view()->setItemDelegate(delegate);
 }