clang/test/SemaCXX/coroutine-traits-undefined-template.cpp

   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++20 -verify %s -fcxx-exceptions -fexceptions -Wunused-result
   5
   6 namespace std {
   7
   8 template<typename ...T>
   9 struct coroutine_traits {
  10   struct promise_type {};
  11 };
  12
  13 template <> struct coroutine_traits<void>; // expected-note {{forward declaration of 'std::coroutine_traits<void>'}}
  14 } // namespace std
  15
  16 void uses_forward_declaration() {
  17   co_return; // expected-error {{this function cannot be a coroutine: missing definition of specialization 'coroutine_traits<void>'}}
  18 }