1 // This file contains references to sections of the Coroutines TS, which can be
2 // found at http://wg21.link/coroutines.
3 
4 // RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -verify %s -fcxx-exceptions -fexceptions -Wunused-result
5 
6 namespace std {
7 namespace experimental {
8 
9 template<typename ...T>
10 struct coroutine_traits {
11   struct promise_type {};
12 };
13 
14 template<> struct coroutine_traits<void>; // expected-note {{forward declaration of 'std::experimental::coroutine_traits<void>'}}
15 }} // namespace std::experimental
16 
uses_forward_declaration()17 void uses_forward_declaration() {
18   co_return; // expected-error {{this function cannot be a coroutine: missing definition of specialization 'coroutine_traits<void>'}}
19 }
20