Fix two anchors following each other

src/multisplitter/AnchorGroup.cpp

@@ -329,9 +329,7 @@ void AnchorGroup::turnIntoPlaceholder()
         if (!right->isStatic())
             right->setPosition(right->position() - ((right->position() - left->position()) / 2));
         left->setFollowee(right);
-    }
-
-    if (right->shouldFollow()) {
+    } else if (right->shouldFollow()) {
         right->setFollowee(left);
     }
 
@@ -340,10 +338,7 @@ void AnchorGroup::turnIntoPlaceholder()
         if (!bottom->isStatic())
             bottom->setPosition(bottom->position() - ((bottom->position() - top->position()) / 2));
         top->setFollowee(bottom);
-    }
-
-
-    if (bottom->shouldFollow()) {
+    } else if (bottom->shouldFollow()) {
         bottom->setFollowee(top);
     }
 

src/multisplitter/MultiSplitterLayout.cpp

@@ -742,6 +742,17 @@ void MultiSplitterLayout::setAnchorBeingDragged(Anchor *anchor)
     m_anchorBeingDragged = anchor;
 }
 
+int MultiSplitterLayout::numAchorsFolllowing() const
+{
+    int count = 0;
+    for (Anchor *a : m_anchors) {
+        if (a->isFollowing())
+            count++;
+    }
+
+    return count;
+}
+
 Anchor *MultiSplitterLayout::staticAnchor(Anchor::Type type) const
 {
     if (type == Anchor::Type_TopStatic)

src/multisplitter/MultiSplitterLayout_p.h

@@ -193,6 +193,9 @@ public:
     ///@brief returns list of separators
     const Anchor::List anchors() const { return m_anchors; }
 
+    ///@brief returns the number of anchors that are following others, just for tests.
+    int numAchorsFolllowing() const;
+
     ///@brief returns either the left, top, right or bottom separator, depending on the @p type
     Anchor *staticAnchor(Anchor::Type type) const;
 

tests/tst_docks.cpp

@@ -286,6 +286,7 @@ private Q_SLOTS:
     void tst_placeholderDisappearsOnReadd();
     void tst_placeholdersAreRemovedPropertly();
     void tst_embeddedMainWindow();
+    void tst_toggleMiddleDockCrash(); // tests some crash I got
 private:
     void tst_restoreEmpty(); // TODO. Disabled for now, save/restore needs to support placeholders
     void tst_restoreCrash(); // TODO. Disabled for now, save/restore needs to support placeholders
@@ -2495,6 +2496,39 @@ void TestDocks::tst_embeddedMainWindow()
 
 }
 
+void TestDocks::tst_toggleMiddleDockCrash()
+{
+    EnsureTopLevelsDeleted e;
+    auto m = createMainWindow(QSize(800, 500), MainWindowOption_None); // Remove central frame
+    auto dropArea = qobject_cast<DropArea*>(m->centralWidget());
+    MultiSplitterLayout *layout = dropArea->multiSplitter();
+    QPointer<DockWidget> dock1 = createDockWidget(QStringLiteral("1"), new QPushButton(QStringLiteral("1")));
+    QPointer<DockWidget> dock2 = createDockWidget(QStringLiteral("2"), new QPushButton(QStringLiteral("2")));
+    QPointer<DockWidget> dock3 = createDockWidget(QStringLiteral("3"), new QPushButton(QStringLiteral("3")));
+
+    m->addDockWidget(dock1, Location_OnLeft);
+    m->addDockWidget(dock2, Location_OnRight);
+    m->addDockWidget(dock3, Location_OnRight);
+
+    QCOMPARE(layout->count(), 3);
+    QCOMPARE(layout->placeholderCount(), 0);
+
+    auto frame = dock2->frame();
+    dock2->close();
+    QVERIFY(waitForDeleted(frame));
+
+    QCOMPARE(layout->count(), 3);
+    QCOMPARE(layout->placeholderCount(), 1);
+    QVERIFY(layout->checkSanity());
+    QCOMPARE(layout->numAchorsFolllowing(), 1);
+
+
+    delete dock2;
+
+
+    //dock2->show();
+}
+
 // QTest::qWait(50000)
 
 QTEST_MAIN(KDDockWidgets::TestDocks)