QStyleSheetStyle::repolish: only run on direct children

When re-parenting, some widgets change their children. For example
QLabel, when set to rich text, will not update, until receiving a polish
call, at which time getting a list of all children recursively and then
trying to call functions on them will crash, since the children change
in the middle of this operation.

Fixes: QTBUG-69204
Fixes: QTBUG-74667
Change-Id: I95dd83ebeed14c017e22552ddd47658ae8a09353
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

2 files changed, 25 insertions, 1 deletions

diff --git a/src/widgets/styles/qstylesheetstyle.cpp b/src/widgets/styles/qstylesheetstyle.cpp
index 73b147e622..4518d8c736 100644
--- a/src/widgets/styles/qstylesheetstyle.cpp
+++ b/src/widgets/styles/qstylesheetstyle.cpp
@@ -2905,7 +2905,10 @@ void QStyleSheetStyle::polish(QPalette &pal)
 
 void QStyleSheetStyle::repolish(QWidget *w)
 {
-    QList<const QObject *> children = w->findChildren<const QObject *>(QString());
+    QList<const QObject *> children;
+    children.reserve(w->children().size() + 1);
+    for (auto child: qAsConst(w->children()))
+        children.append(child);
     children.append(w);
     styleSheetCaches->styleSheetCache.remove(w);
     updateObjects(children);
diff --git a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
index 0e5c40f1b6..8760ed0373 100644
--- a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
+++ b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
@@ -48,6 +48,7 @@ public:
 private slots:
     void init();
     void repolish();
+    void repolish_without_crashing();
     void numinstances();
     void widgetsBeforeAppStyleSheet();
     void widgetsAfterAppStyleSheet();
@@ -367,6 +368,26 @@ void tst_QStyleSheetStyle::repolish()
     QCOMPARE(BACKGROUND(p1), APPBACKGROUND(p1));
 }
 
+void tst_QStyleSheetStyle::repolish_without_crashing()
+{
+    // This used to crash, QTBUG-69204
+    QMainWindow w;
+    QScopedPointer<QSplitter> splitter1(new QSplitter(w.centralWidget()));
+    QScopedPointer<QSplitter> splitter2(new QSplitter);
+    QScopedPointer<QSplitter> splitter3(new QSplitter);
+    splitter2->addWidget(splitter3.data());
+
+    splitter2->setStyleSheet("color: red");
+    QScopedPointer<QLabel> label(new QLabel);
+    label->setTextFormat(Qt::RichText);
+    splitter3->addWidget(label.data());
+    label->setText("hey");
+
+    splitter1->addWidget(splitter2.data());
+    w.show();
+    QCOMPARE(COLOR(*label), QColor(Qt::red));
+}
+
 void tst_QStyleSheetStyle::widgetStyle()
 {
     qApp->setStyleSheet("");