QWidget::mapTo()/mapFrom(): Do not crash if parent argument is invalid

These functions iterate through the parent hierarchy until the widget
given as argument is found. If never found, the code would assert (in
debug mode) or just silently crash (in release mode).

No need to bring down the entire application just because some widget
coordinate calculation is off. Instead, just emit a qWarning and
return cleanly.

Task-number: QTBUG-132072
Pick-to: 6.9 6.8
Change-Id: I4d13f46037cdcf855f76e040f941a8a7050ab12b
Reviewed-by: Richard Moe Gustavsen <[email protected]>

1 files changed, 8 insertions, 5 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index dc1abe70cc4..683285011f5 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -4219,10 +4219,12 @@ QPointF QWidget::mapTo(const QWidget *parent, const QPointF &pos) const
     if (parent) {
         const QWidget * w = this;
         while (w != parent) {
-            Q_ASSERT_X(w, "QWidget::mapTo(const QWidget *parent, const QPointF &pos)",
-                       "parent must be in parent hierarchy");
             p = w->mapToParent(p);
             w = w->parentWidget();
+            if (!w) {
+                qWarning("QWidget::mapTo(): parent must be in parent hierarchy");
+                break;
+            }
         }
     }
     return p;
@@ -4251,11 +4253,12 @@ QPointF QWidget::mapFrom(const QWidget *parent, const QPointF &pos) const
     if (parent) {
         const QWidget * w = this;
         while (w != parent) {
-            Q_ASSERT_X(w, "QWidget::mapFrom(const QWidget *parent, const QPoint &pos)",
-                       "parent must be in parent hierarchy");
-
             p = w->mapFromParent(p);
             w = w->parentWidget();
+            if (!w) {
+                qWarning("QWidget::mapFrom(): parent must be in parent hierarchy");
+                break;
+            }
         }
     }
     return p;