Fix alias resolution algorithm

The resolution of aliases needs to to be solved in iterations as an alias can
refer to another alias, which may not be created yet in the property cache by
the time we try to perform the resolution. Therefore the alias resolution code
works off a list of pending aliases after the initial pass of resolution. This
also requires the ability to detect circular references.

Change-Id: Id4e159b9c713aa8a8a095759e22e3fac456a38a0
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

5 files changed, 45 insertions, 3 deletions

diff --git a/tests/auto/qml/qqmllanguage/data/alias.14.errors.txt b/tests/auto/qml/qqmllanguage/data/alias.14.errors.txt
new file mode 100644
index 0000000000..90a3ea4317
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/alias.14.errors.txt
@@ -0,0 +1 @@
+10:34:References to other aliases within the same object are not supported at the moment
diff --git a/tests/auto/qml/qqmllanguage/data/alias.14.qml b/tests/auto/qml/qqmllanguage/data/alias.14.qml
new file mode 100644
index 0000000000..ff3c36d990
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/alias.14.qml
@@ -0,0 +1,17 @@
+import QtQml 2.0
+
+QtObject {
+    id: root
+    property bool targetProperty: true
+
+    property QtObject foo: QtObject {
+        id: otherSubObject
+        property alias theAliasOrigin: root.targetProperty
+        property alias theAlias: otherSubObject.theAliasOrigin
+    }
+
+    property QtObject referencingSubObject: QtObject {
+        property alias success: otherSubObject.theAlias
+    }
+
+}
diff --git a/tests/auto/qml/qqmllanguage/data/invalidAlias.11.errors.txt b/tests/auto/qml/qqmllanguage/data/invalidAlias.11.errors.txt
new file mode 100644
index 0000000000..b79b660c46
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/invalidAlias.11.errors.txt
@@ -0,0 +1 @@
+5:5:Circular alias reference detected
diff --git a/tests/auto/qml/qqmllanguage/data/invalidAlias.11.qml b/tests/auto/qml/qqmllanguage/data/invalidAlias.11.qml
new file mode 100644
index 0000000000..9b50b48df8
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/invalidAlias.11.qml
@@ -0,0 +1,10 @@
+import QtQml 2.0
+
+QtObject {
+    id: root
+    property alias a: subObject.b
+    property QtObject foo: QtObject {
+        id: subObject
+        property alias b: root.a
+    }
+}
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index 1e8e92217c..1df7c4157e 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -494,6 +494,7 @@ void tst_qqmllanguage::errors_data()
     QTest::newRow("invalidAlias.8") << "invalidAlias.8.qml" << "invalidAlias.8.errors.txt" << false;
     QTest::newRow("invalidAlias.9") << "invalidAlias.9.qml" << "invalidAlias.9.errors.txt" << false;
     QTest::newRow("invalidAlias.10") << "invalidAlias.10.qml" << "invalidAlias.10.errors.txt" << false;
+    QTest::newRow("invalidAlias.11") << "invalidAlias.11.qml" << "invalidAlias.11.errors.txt" << false;
 
     QTest::newRow("invalidAttachedProperty.1") << "invalidAttachedProperty.1.qml" << "invalidAttachedProperty.1.errors.txt" << false;
     QTest::newRow("invalidAttachedProperty.2") << "invalidAttachedProperty.2.qml" << "invalidAttachedProperty.2.errors.txt" << false;
@@ -1821,8 +1822,6 @@ void tst_qqmllanguage::aliasProperties()
     {
         // This is known to fail at the moment.
         QQmlComponent component(&engine, testFileUrl("alias.13.qml"));
-        QVERIFY(!component.errors().isEmpty());
-#if 0
         VERIFY_ERRORS(0);
         QScopedPointer<QObject> object(component.create());
         QVERIFY(!object.isNull());
@@ -1831,7 +1830,21 @@ void tst_qqmllanguage::aliasProperties()
         QVERIFY(!subObject.isNull());
 
         QVERIFY(subObject->property("success").toBool());
-#endif
+    }
+
+    // "Nested" aliases within an object that require iterative resolution
+    {
+        // This is known to fail at the moment.
+        QQmlComponent component(&engine, testFileUrl("alias.14.qml"));
+        VERIFY_ERRORS(0);
+
+        QScopedPointer<QObject> object(component.create());
+        QVERIFY(!object.isNull());
+
+        QPointer<QObject> subObject = qvariant_cast<QObject*>(object->property("referencingSubObject"));
+        QVERIFY(!subObject.isNull());
+
+        QVERIFY(subObject->property("success").toBool());
     }
 }