1 // PR c++/81188
2 // { dg-do compile { target c++11 } }
3 
4 template <class F>
5 struct C {
6   F fast(long i) const;
7   auto operator[](long i) const -> decltype(this->fast(i));
8 };
9 
10 template <class F>
11 auto C<F>::operator[](long i) const -> decltype(this->fast(i)) {
12   return fast(i);
13 }
14