C++: fix dereferencing of nested type and operator '->'

Fixed case:
template<class T>
struct List
{
  struct iterator
  {
    T *operator->() { return &t; }
    T t;
  };
  iterator begin() { return iterator(); }
};

struct Foo { int bar; };

void func()
{
  List<Foo> list;
  list.begin()->; // code completion doesn't work
}

Task-number: QTCREATORBUG-13799
Change-Id: I65e8d3092bbc9b01a5dbee241c24d95dd03fc670
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/libs/cplusplus/ResolveExpression.cpp

@@ -1078,8 +1078,9 @@ ClassOrNamespace *ResolveExpression::baseExpression(const QList<LookupItem> &bas
                 ClassOrNamespace *binding
                         = findClassForTemplateParameterInExpressionScope(r.binding(),
                                                                          ty);
+
                 if (! binding)
-                    binding = findClass(ty, scope);
+                    binding = findClass(ty, scope, r.binding());
 
                 if (binding){
                     // lookup for overloads of operator->

src/plugins/cpptools/cppcompletion_test.cpp

@@ -2533,6 +2533,26 @@ void CppToolsPlugin::test_completion_data()
     ) << _("(*list.begin()).") << (QStringList()
         << QLatin1String("Foo")
         << QLatin1String("bar"));
+
+    QTest::newRow("dereference_of_nested_type_opertor_->") << _(
+            "template<typename T>\n"
+            "struct QList\n"
+            "{\n"
+            "   struct iterator\n"
+            "   {\n"
+            "      T *operator->() { return &t; }\n"
+            "      T t;\n"
+            "   };\n"
+            "   iterator begin() { return iterator(); }\n"
+            "};\n"
+            "struct Foo { int bar; };\n"
+            "void fun() {\n"
+            "   QList<Foo> list;\n"
+            "   @\n"
+            "}\n"
+    ) << _("list.begin()->") << (QStringList()
+        << QLatin1String("Foo")
+        << QLatin1String("bar"));
 }
 
 void CppToolsPlugin::test_completion_member_access_operator()