redifinition of struct hash<coroutine_handle<_Tp> >

[TannyXie]

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What happened + What you expected to happen

I'm on MacOS and I use g++-11 (11.2.0) for both CXX and CC. I come across the error when build.

/async_simple/async_simple/experimental/coroutine.h:400:8: error: 
      redefinition of 'hash<coroutine_handle<_Tp> >'
struct hash<coroutine_handle<_Tp> > {
/include/c++/v1/experimental/coroutine:323:8: note: 
      previous definition is here
struct hash<_VSTD_CORO::coroutine_handle<_Tp> > {

Reproduction way

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Are you willing to submit a PR?

• Yes I am willing to submit a PR!

[ChuanqiXu9]

It is weird. I remember I met the problem before and have fixed it. Would you like to check the commit id?

[TannyXie]

I'm on commit e342335.

[ChuanqiXu9]

I'm on commit e342335.

Would you like to move to HEAD? It should be able to solve this.

[TannyXie]

I'm getting a new error.

async_simple/async_simple/Common.h:44:9: error: unknown attribute 'likely' ignored [-Werror,-Wunknown-attributes]
        LIKELY { return; }
        ^
async_simple/async_simple/Common.h:25:18: note: expanded from macro 'LIKELY'
#define LIKELY [[likely]]
                 ^

[qicosmos]

I think it's the compiler problem, use a c++ compiler which can support c++20.

[ChuanqiXu9]

I'm getting a new error.

async_simple/async_simple/Common.h:44:9: error: unknown attribute 'likely' ignored [-Werror,-Wunknown-attributes]
        LIKELY { return; }
        ^
async_simple/async_simple/Common.h:25:18: note: expanded from macro 'LIKELY'
#define LIKELY [[likely]]
                 ^

It is odd since we've tried GCC-10.3 it is in the CI system. But our method of detecting the presence of [[likely]] is not good enough as well. I've sent #120. Would you like to try again?

[TannyXie]

In file included from /Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:16:
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/FutureAwaiter.h:44:35: error: expected ';' at end of declaration
auto operator co_await(T&& future) requires IsFuture<std::decay_t<T>>::value {
                                  ^
                                  ;
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/FutureAwaiter.h:44:36: error: expected unqualified-id
auto operator co_await(T&& future) requires IsFuture<std::decay_t<T>>::value {
                                   ^
In file included from /Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:17:
In file included from /Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/Lazy.h:22:
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/ViaCoroutine.h:97:25: error: function 'operator co_await<std::experimental::coroutines_v1::suspend_always>' with deduced return type cannot
      be used before it is defined
    static ViaCoroutine create(Executor* ex) { co_return; }
                        ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/FutureAwaiter.h:44:6: note: 'operator co_await<std::experimental::coroutines_v1::suspend_always>' declared here
auto operator co_await(T&& future) requires IsFuture<std::decay_t<T>>::value {
     ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:41:18: error: function 'operator co_await<std::experimental::coroutines_v1::suspend_always>' with deduced return
      type cannot be used before it is defined
    auto lazy1 = [&]() -> Lazy<> {
                 ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/FutureAwaiter.h:44:6: note: 'operator co_await<std::experimental::coroutines_v1::suspend_always>' declared here
auto operator co_await(T&& future) requires IsFuture<std::decay_t<T>>::value {
     ^
In file included from /Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:17:
In file included from /Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/Lazy.h:22:
In file included from /Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/ViaCoroutine.h:30:
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/Traits.h:70:12: error: call to deleted constructor of 'async_simple::Future<int>'
    return std::forward<Awaitable>(awaitable);
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/ViaCoroutine.h:183:26: note: in instantiation of function template specialization
      'async_simple::coro::detail::getAwaiter<async_simple::Future<int> &, 0, 0>' requested here
        decltype(detail::getAwaiter(std::forward<Awaitable>(awaitable)));
                         ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/Lazy.h:97:24: note: in instantiation of function template specialization
      'async_simple::coro::detail::coAwait<async_simple::Future<int> &, 0>' requested here
        return detail::coAwait(_executor, std::forward<Awaitable>(awaitable));
                       ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:46:20: note: in instantiation of function template specialization
      'async_simple::coro::detail::LazyPromiseBase::await_transform<async_simple::Future<int> &>' requested here
        auto val = co_await fut;
                   ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/Future.h:63:5: note: 'Future' has been explicitly marked deleted here
    Future(const Future&) = delete;
    ^
In file included from /Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:17:
In file included from /Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/Lazy.h:22:
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/ViaCoroutine.h:139:34: error: no member named 'await_suspend' in 'async_simple::Future<int>'
        std::declval<Awaiter&>().await_suspend(std::declval<HandleType>()));
        ~~~~~~~~~~~~~~~~~~~~~~~~ ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/ViaCoroutine.h:184:12: note: in instantiation of template class 'async_simple::coro::detail::ViaAsyncAwaiter<async_simple::Future<int> >'
      requested here
    return ViaAsyncAwaiter<std::decay_t<AwaiterType>>(
           ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/Lazy.h:97:24: note: in instantiation of function template specialization
      'async_simple::coro::detail::coAwait<async_simple::Future<int> &, 0>' requested here
        return detail::coAwait(_executor, std::forward<Awaitable>(awaitable));
                       ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:46:20: note: in instantiation of function template specialization
      'async_simple::coro::detail::LazyPromiseBase::await_transform<async_simple::Future<int> &>' requested here
        auto val = co_await fut;
                   ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:46:20: note: call to 'await_transform' implicitly required by 'co_await' here
        auto val = co_await fut;
                   ^        ~~~
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:50:18: error: function 'operator co_await<std::experimental::coroutines_v1::suspend_always>' with deduced return
      type cannot be used before it is defined
    auto lazy2 = [&]() -> Lazy<> {
                 ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/FutureAwaiter.h:44:6: note: 'operator co_await<std::experimental::coroutines_v1::suspend_always>' declared here
auto operator co_await(T&& future) requires IsFuture<std::decay_t<T>>::value {
     ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/test/FutureAwaiterTest.cpp:57:20: error: function 'operator co_await<async_simple::coro::detail::ViaAsyncAwaiter<async_simple::Future<int> >
      >' with deduced return type cannot be used before it is defined
        auto val = co_await std::move(fut);
                   ^
/Users/tannyxie/Documents/Project Preparation/github/async_simple/async_simple/coro/FutureAwaiter.h:44:6: note: 'operator co_await<async_simple::coro::detail::ViaAsyncAwaiter<async_simple::Future<int> > >' declared here
auto operator co_await(T&& future) requires IsFuture<std::decay_t<T>>::value {
     ^
8 errors generated.
make[2]: *** [async_simple/coro/test/CMakeFiles/async_simple_coro_test.dir/FutureAwaiterTest.cpp.o] Error 1
make[1]: *** [async_simple/coro/test/CMakeFiles/async_simple_coro_test.dir/all] Error 2
make: *** [all] Error 2

[ChuanqiXu9]

It looks like your compiler is not new enough indeed. It couldn't recognize requires keyword. Would you like to check the used compiler?