qmllint: Consider "on-bindings" for required properties

The runtime doesn't complain if a required property is satisfied via a
ValueSource or an Interceptor, so qmllint shouldn't complain either.

Whether this really should apply to interceptors is debatable, but for
now let's aim for consistency. And that a ValueSource can satifsy the
requirement is arguably to be expected.

Pick-to: 6.10 6.8
Fixes: QTBUG-139632
Change-Id: I355b8a48e6b9bc2749839267c3b799e8eba5d72f
Reviewed-by: Olivier De Cannière <olivier.decanniere@qt.io>

src/qmlcompiler/qqmljsimportvisitor.cpp

@@ -1149,7 +1149,11 @@ void QQmlJSImportVisitor::checkRequiredProperties()
                 continue;
             const auto &[begin, end] = scope->ownPropertyBindings(propName);
             for (auto it = begin; it != end; ++it) {
-                if (!QQmlSA::isRegularBindingType(it->bindingType()))
+                // attached and grouped bindings should not be considered here
+                const bool isRelevantBinding = QQmlSA::isRegularBindingType(it->bindingType())
+                        || it->bindingType() == QQmlSA::BindingType::Interceptor
+                        || it->bindingType() == QQmlSA::BindingType::ValueSource;
+                if (!isRelevantBinding)
                     continue;
                 if (QQmlJSScope::ownerOfProperty(scope, propName).scope == owner)
                     return true;

tests/auto/qml/qmllint/data/requiredPropertySetViaOnBinding.qml

@@ -0,0 +1,27 @@
+import QtQuick
+
+Window {
+    id: window
+    width: 640
+    height: 480
+    visible: true
+
+    property int refValue: 0
+
+    component TestObject: QtObject {
+        required property int value
+    }
+
+
+    TestObject {
+        // consistent with runtime
+        Behavior on value {}
+    }
+
+    TestObject {
+        Binding on value {
+            value: 42
+        }
+    }
+}
+

tests/auto/qml/qmllint/tst_qmllint.cpp

@@ -2287,6 +2287,7 @@ void TestQmllint::cleanQmlCode_data()
     QTest::newRow("qualifiedAttached")         << QStringLiteral("Drawer.qml");
     QTest::addRow("regExp") << u"regExp.qml"_s;
     QTest::newRow("requiredPropertyInGroupedPropertyScope") << QStringLiteral("requiredPropertyInGroupedPropertyScope.qml");
+    QTest::newRow("requiredPropertySetViaOnBinding") << QStringLiteral("requiredPropertySetViaOnBinding.qml");
     QTest::newRow("requiredWithRootLevelAlias") << QStringLiteral("RequiredWithRootLevelAlias.qml");
     QTest::newRow("required_property_in_Component") << QStringLiteral("requiredPropertyInComponent.qml");
     QTest::newRow("retrieveFunction") << QStringLiteral("retrieveFunction.qml");