Don't try to look up members of attached properties.

src/libs/qmljs/qmljscheck.cpp

@@ -190,8 +190,11 @@ void Check::checkScopeObjectMember(const UiQualifiedId *id)
         return;
 
     // attached properties
-    if (! propertyName.isEmpty() && propertyName[0].isUpper())
+    bool isAttachedProperty = false;
+    if (! propertyName.isEmpty() && propertyName[0].isUpper()) {
+        isAttachedProperty = true;
         scopeObject = _context.typeEnvironment(_doc.data());
+    }
 
     if (! scopeObject)
         return;
@@ -206,6 +209,10 @@ void Check::checkScopeObjectMember(const UiQualifiedId *id)
         return;
     }
 
+    // can't look up members for attached properties
+    if (isAttachedProperty)
+        return;
+
     // member lookup
     const UiQualifiedId *idPart = id;
     while (idPart->next) {