Binding: Reevaluate when before the target changes

...and do not warn about missing properties if when is disabled. Besides
avoiding spurious warnings, this also avoids modifying a property only
to restore its binding/value directly afterwards.

Note that when the binding gets re-enabled, we still trigger the
warning.

Fixes: QTBUG-112860
Pick-to: 6.5
Change-Id: I5ddd32f2de2dec9da372b08ab4bb5bdb88873e51
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Sami Shalayel <sami.shalayel@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlbinding/data/whenEvaluatedEarlyEnough.qml b/tests/auto/qml/qqmlbinding/data/whenEvaluatedEarlyEnough.qml
new file mode 100644
index 0000000000..6245270e14
--- /dev/null
+++ b/tests/auto/qml/qqmlbinding/data/whenEvaluatedEarlyEnough.qml
@@ -0,0 +1,23 @@
+import QtQuick
+
+Item {
+    id: root
+    property bool toggle: true
+    property bool forceEnable: false
+
+    Item {
+        id: item1
+        property int i
+    }
+
+    Item {
+        id: item2
+    }
+
+    Binding {
+        target: root.toggle ? item1 : item2 
+        when:  root.forceEnable || (root.toggle ? item1 : item2).hasOwnProperty("i")
+        property: "i"
+        value: 42
+    }
+}