qmltypes: Handle extension property

Previously Qt Creator ignored the extension property in qmltypes leading to
auto-complete being unavailable for some properties of extended types among other things.

Change-Id: I1bc13b3daf9bbd0a835e9a25f52b9589ad942e75
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/libs/languageutils/fakemetaobject.cpp

@@ -369,6 +369,11 @@ QString FakeMetaObject::attachedTypeName() const
 void FakeMetaObject::setAttachedTypeName(const QString &name)
 { m_attachedTypeName = name; }
 
+QString FakeMetaObject::extensionTypeName() const
+{ return m_extensionTypeName; }
+void FakeMetaObject::setExtensionTypeName(const QString &name)
+{ m_extensionTypeName = name; }
+
 QByteArray FakeMetaObject::calculateFingerprint() const
 {
     QCryptographicHash hash(QCryptographicHash::Sha1);

src/libs/languageutils/fakemetaobject.h

@@ -170,6 +170,7 @@ private:
     QList<FakeMetaMethod> m_methods;
     QString m_defaultPropertyName;
     QString m_attachedTypeName;
+    QString m_extensionTypeName;
     QByteArray m_fingerprint;
     bool m_isSingleton;
     bool m_isCreatable;
@@ -212,6 +213,8 @@ public:
 
     QString attachedTypeName() const;
     void setAttachedTypeName(const QString &name);
+    QString extensionTypeName() const;
+    void setExtensionTypeName(const QString &name);
     QByteArray calculateFingerprint() const;
     void updateFingerprint();
     QByteArray fingerprint() const;

src/libs/qmljs/qmljsinterpreter.cpp

@@ -358,6 +358,14 @@ void CppComponentValue::processMembers(MemberProcessor *processor) const
             attachedType->processMembers(processor);
     }
 
+    // look at extension types
+    const QString &extensionTypeName = m_metaObject->extensionTypeName();
+    if (!extensionTypeName.isEmpty()) {
+        const CppComponentValue *extensionType = valueOwner()->cppQmlTypes().objectByCppName(extensionTypeName);
+        if (extensionType && extensionType != this) // ### only weak protection against infinite loops
+            extensionType->processMembers(processor);
+    }
+
     ObjectValue::processMembers(processor);
 }
 

src/libs/qmljs/qmljstypedescriptionreader.cpp

@@ -228,6 +228,8 @@ void TypeDescriptionReader::readComponent(UiObjectDefinition *ast)
                 readMetaObjectRevisions(script, fmo);
             } else if (name == QLatin1String("attachedType")) {
                 fmo->setAttachedTypeName(readStringBinding(script));
+            } else if (name == QLatin1String("extension")) {
+                fmo->setExtensionTypeName(readStringBinding(script));
             } else if (name == QLatin1String("isSingleton")) {
                 fmo->setIsSingleton(readBoolBinding(script));
             } else if (name == QLatin1String("isCreatable")) {