QTabBar: fix QStyleOptionTab::position

During 556712f511a02ff8101e648d2e6f0090231d4f3d a small regression was
introduced which set a wrong value for QStyleOptionTab::position.

Fixes: QTBUG-81393
Change-Id: Ie8c66186b1b79c97bf77c7b139e08840233b7b66
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

2 files changed, 27 insertions, 11 deletions

diff --git a/src/widgets/widgets/qtabbar.cpp b/src/widgets/widgets/qtabbar.cpp
index a7b115a1bc..df480629da 100644
--- a/src/widgets/widgets/qtabbar.cpp
+++ b/src/widgets/widgets/qtabbar.cpp
@@ -208,7 +208,7 @@ void QTabBarPrivate::initBasicStyleOption(QStyleOptionTab *option, int tabIndex)
         option->selectedPosition = QStyleOptionTab::NotAdjacent;
 
     const bool paintBeginning = (tabIndex == firstVisible) || (dragInProgress && tabIndex == pressedIndex + 1);
-    const bool paintEnd = (tabIndex == lastVisible - 1) || (dragInProgress && tabIndex == pressedIndex - 1);
+    const bool paintEnd = (tabIndex == lastVisible) || (dragInProgress && tabIndex == pressedIndex - 1);
     if (paintBeginning) {
         if (paintEnd)
             option->position = QStyleOptionTab::OnlyOneTab;
diff --git a/tests/auto/widgets/widgets/qtabbar/tst_qtabbar.cpp b/tests/auto/widgets/widgets/qtabbar/tst_qtabbar.cpp
index bc1496d0f6..e27600bad2 100644
--- a/tests/auto/widgets/widgets/qtabbar/tst_qtabbar.cpp
+++ b/tests/auto/widgets/widgets/qtabbar/tst_qtabbar.cpp
@@ -33,6 +33,7 @@
 
 #include <qpushbutton.h>
 #include <qstyle.h>
+#include <qstyleoption.h>
 
 class tst_QTabBar : public QObject
 {
@@ -279,30 +280,53 @@ void tst_QTabBar::hideTab()
     QTEST(tabbar.currentIndex(), "finalIndex");
 }
 
+class TabBar : public QTabBar
+{
+public:
+    using QTabBar::QTabBar;
+    using QTabBar::initStyleOption;
+    using QTabBar::moveTab;
+};
+
 void tst_QTabBar::hideAllTabs()
 {
-    QTabBar tabbar;
+    TabBar tabbar;
+    auto checkPositions = [&tabbar](const QVector<int> &positions)
+    {
+        QStyleOptionTab option;
+        int iPos = 0;
+        for (int i = 0; i < tabbar.count(); ++i) {
+            if (!tabbar.isTabVisible(i))
+                continue;
+            tabbar.initStyleOption(&option, i);
+            QCOMPARE(option.position, positions.at(iPos++));
+        }
+    };
 
     tabbar.addTab("foo");
     tabbar.addTab("bar");
     tabbar.addTab("baz");
     tabbar.setCurrentIndex(0);
+    checkPositions({QStyleOptionTab::Beginning, QStyleOptionTab::Middle, QStyleOptionTab::End});
 
     // Check we don't crash trying to hide an unexistant tab
     QSize prevSizeHint = tabbar.sizeHint();
     tabbar.setTabVisible(3, false);
+    checkPositions({QStyleOptionTab::Beginning, QStyleOptionTab::Middle, QStyleOptionTab::End});
     QCOMPARE(tabbar.currentIndex(), 0);
     QSize sizeHint = tabbar.sizeHint();
     QVERIFY(sizeHint.width() == prevSizeHint.width());
     prevSizeHint = sizeHint;
 
     tabbar.setTabVisible(1, false);
+    checkPositions({QStyleOptionTab::Beginning, QStyleOptionTab::End});
     QCOMPARE(tabbar.currentIndex(), 0);
     sizeHint = tabbar.sizeHint();
     QVERIFY(sizeHint.width() < prevSizeHint.width());
     prevSizeHint = sizeHint;
 
     tabbar.setTabVisible(2, false);
+    checkPositions({QStyleOptionTab::OnlyOneTab});
     QCOMPARE(tabbar.currentIndex(), 0);
     sizeHint = tabbar.sizeHint();
     QVERIFY(sizeHint.width() < prevSizeHint.width());
@@ -571,14 +595,6 @@ void tst_QTabBar::selectionBehaviorOnRemove()
     QCOMPARE(tabbar.currentIndex(), expected);
 }
 
-class TabBar : public QTabBar
-{
-    Q_OBJECT
-public:
-    void callMoveTab(int from, int to){ moveTab(from, to); }
-};
-
-
 Q_DECLARE_METATYPE(QTabBar::Shape)
 void tst_QTabBar::moveTab_data()
 {
@@ -613,7 +629,7 @@ void tst_QTabBar::moveTab()
     bar.setShape(shape);
     while(--tabs >= 0)
         bar.addTab(QString::number(tabs));
-    bar.callMoveTab(from, to);
+    bar.moveTab(from, to);
 }