Layouts: reimplement toString() for better warning messages

When combined with the patch in qtbase that adds the virtual toString
function to QGridLayoutItem, this turns the following warning

    QGridLayoutEngine::addItem: Cell (1, 0) already taken

into the much more informative

    QGridLayoutEngine::addItem: Can't add QQuickRectangle(0x6110000d5100, id="r4", parent=0x6110000d4ac0, geometry=0,0 20x20) at cell (1, 0) because it's already taken by QQuickRectangle(0x6110000d4e80, id="r2", parent=0x6110000d4ac0, geometry=0,0 20x20)

This makes it easier to see which item warnings are referring to.

Change-Id: I80a85b77abcb404fb0d6bc622baa1be3cd9e0df5
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

3 files changed, 4 insertions, 1 deletions

diff --git a/src/quicklayouts/qquickgridlayoutengine_p.h b/src/quicklayouts/qquickgridlayoutengine_p.h
index a59679761d..047d214655 100644
--- a/src/quicklayouts/qquickgridlayoutengine_p.h
+++ b/src/quicklayouts/qquickgridlayoutengine_p.h
@@ -86,6 +86,8 @@ public:
         }
     }
 
+    inline virtual QString toString() const override { return QDebug::toString(m_item); }
+
     QQuickItem *layoutItem() const { return m_item; }
 
     QQuickItem *m_item;
diff --git a/src/quicklayouts/qquicklinearlayout.cpp b/src/quicklayouts/qquicklinearlayout.cpp
index 25c5e62632..2fa3c7e820 100644
--- a/src/quicklayouts/qquicklinearlayout.cpp
+++ b/src/quicklayouts/qquicklinearlayout.cpp
@@ -811,6 +811,7 @@ void QQuickGridLayout::insertLayoutItems()
             layoutItem->setStretchFactor(hStretch, Qt::Horizontal);
         if (vStretch >= 0)
             layoutItem->setStretchFactor(vStretch, Qt::Vertical);
+
         d->engine.insertItem(layoutItem, -1);
     }
 }
diff --git a/tests/auto/quick/qquicklayouts/data/tst_gridlayout.qml b/tests/auto/quick/qquicklayouts/data/tst_gridlayout.qml
index d03a8006b4..f311cc34d6 100644
--- a/tests/auto/quick/qquicklayouts/data/tst_gridlayout.qml
+++ b/tests/auto/quick/qquicklayouts/data/tst_gridlayout.qml
@@ -208,7 +208,7 @@ Item {
         }
 
         function test_flowLeftToRightDefaultPositions() {
-            ignoreWarning("QGridLayoutEngine::addItem: Cell (1, 0) already taken");
+            ignoreWarning(/QGridLayoutEngine::addItem: Can't add .* at cell \(1, 0\) because it's already taken by .*/);
             var layout = createTemporaryObject(layout_flowLeftToRightDefaultPositions_Component, container);
             compare(layout.implicitWidth, 40);
             compare(layout.children[0].x, 0);