Fix crash in ListView with PullBackHeader/Footer

The header/footer positioning code would otherwise call qBound() with
max < min when a PullBackHeader/Footer is used and the delegates do not
fill the whole content area (i.e. the list does not need scrolling).
After qtbase ad5c5bb541ae20a205ac07122153b302dee1d3e1 that was causing
an assertion failure.

Even though relying on the old qBound() behavior seems strange, it
does produce the correct header/footer positioning, while swapping
the min/max values (in case max < min) does not. So we need to call
qMin and qMax explicitly rather than using qBound, to avoid the assert.

Task-number: QTBUG-104679
Pick-to: 6.4 6.5
Change-Id: Iefc50e347e77ed51c6d90ddbc6e1cf21d76fc62c
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

3 files changed, 65 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklistview2/data/qtbug104679_footer.qml b/tests/auto/quick/qquicklistview2/data/qtbug104679_footer.qml
new file mode 100644
index 0000000000..919cf4d2ec
--- /dev/null
+++ b/tests/auto/quick/qquicklistview2/data/qtbug104679_footer.qml
@@ -0,0 +1,21 @@
+import QtQuick
+
+Rectangle {
+    width: 640
+    height: 480
+
+    ListView {
+        anchors.fill: parent
+        spacing: 5
+
+        footerPositioning: ListView.PullBackFooter
+        footer: Rectangle { width: ListView.view.width; color: "blue"; implicitHeight: 46 }
+
+        model: 3 // crashed if less items than a full list page
+        delegate: Rectangle {
+            width: ListView.view.width
+            height: 50
+            color: index % 2 ? "black" : "gray"
+        }
+    }
+}
diff --git a/tests/auto/quick/qquicklistview2/data/qtbug104679_header.qml b/tests/auto/quick/qquicklistview2/data/qtbug104679_header.qml
new file mode 100644
index 0000000000..40ddf27988
--- /dev/null
+++ b/tests/auto/quick/qquicklistview2/data/qtbug104679_header.qml
@@ -0,0 +1,21 @@
+import QtQuick
+
+Rectangle {
+    width: 640
+    height: 480
+
+    ListView {
+        anchors.fill: parent
+        spacing: 5
+
+        headerPositioning: ListView.PullBackHeader
+        header: Rectangle { width: ListView.view.width; color: "red"; implicitHeight: 46 }
+
+        model: 3 // crashed if less items than a full list page
+        delegate: Rectangle {
+            width: ListView.view.width
+            height: 50
+            color: index % 2 ? "black" : "gray"
+        }
+    }
+}
diff --git a/tests/auto/quick/qquicklistview2/tst_qquicklistview2.cpp b/tests/auto/quick/qquicklistview2/tst_qquicklistview2.cpp
index e5db492550..a86504599c 100644
--- a/tests/auto/quick/qquicklistview2/tst_qquicklistview2.cpp
+++ b/tests/auto/quick/qquicklistview2/tst_qquicklistview2.cpp
@@ -50,6 +50,8 @@ private slots:
     void isCurrentItem_DelegateModel();
     void isCurrentItem_NoRegressionWithDelegateModelGroups();
 
+    void pullbackSparseList();
+
 private:
     void flickWithTouch(QQuickWindow *window, const QPoint &from, const QPoint &to);
     QScopedPointer<QPointingDevice> touchDevice = QScopedPointer<QPointingDevice>(QTest::createTouchDevice());
@@ -908,6 +910,27 @@ void tst_QQuickListView2::isCurrentItem_NoRegressionWithDelegateModelGroups()
     QCOMPARE(item3->property("isCurrent").toBool(), false);
 }
 
+void tst_QQuickListView2::pullbackSparseList() // QTBUG_104679
+{
+    // check if PullbackHeader crashes
+    QScopedPointer<QQuickView> window(createView());
+    QVERIFY(window);
+    window->setSource(testFileUrl("qtbug104679_header.qml"));
+    QVERIFY2(window->status() == QQuickView::Ready, qPrintable(QDebug::toString(window->errors())));
+    window->resize(640, 480);
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+
+    // check if PullbackFooter crashes
+    window.reset(createView());
+    QVERIFY(window);
+    window->setSource(testFileUrl("qtbug104679_footer.qml"));
+    QVERIFY2(window->status() == QQuickView::Ready, qPrintable(QDebug::toString(window->errors())));
+    window->resize(640, 480);
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+}
+
 QTEST_MAIN(tst_QQuickListView2)
 
 #include "tst_qquicklistview2.moc"