Chuanqi Xu ec117158a3 [Coroutines] [Frontend] Lookup in std namespace first
Now in libcxx and clang, all the coroutine components are defined in
std::experimental namespace.
And now the coroutine TS is merged into C++20. So in the working draft
like N4892, we could find the coroutine components is defined in std
namespace instead of std::experimental namespace.
And the coroutine support in clang seems to be relatively stable. So I
think it may be suitable to move the coroutine component into the
experiment namespace now.

This patch would make clang lookup coroutine_traits in std namespace
first. For the compatibility consideration, clang would lookup in
std::experimental namespace if it can't find definitions in std
namespace. So the existing codes wouldn't be break after update
compiler.

And in case the compiler found std::coroutine_traits and
std::experimental::coroutine_traits at the same time, it would emit an
error for it.

The support for looking up std::experimental::coroutine_traits would be
removed in Clang16.

Reviewed By: lxfind, Quuxplusone

Differential Revision: https://reviews.llvm.org/D108696
2021-11-04 11:53:47 +08:00

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1.0 KiB
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// RUN: %clang_cc1 -triple x86_64-apple-darwin9 %s -std=c++20 -fsyntax-only -Wignored-qualifiers -Wno-error=return-type -verify -fblocks -Wno-unreachable-code -Wno-unused-value
#ifndef STD_COROUTINE_H
#define STD_COROUTINE_H
namespace std {
template <class Ret, typename... T>
struct coroutine_traits { using promise_type = typename Ret::promise_type; };
template <class Promise = void>
struct coroutine_handle {
static coroutine_handle from_address(void *) noexcept;
};
template <>
struct coroutine_handle<void> {
template <class PromiseType>
coroutine_handle(coroutine_handle<PromiseType>) noexcept;
static coroutine_handle from_address(void *);
};
struct suspend_always {
bool await_ready() noexcept { return false; }
void await_suspend(coroutine_handle<>) noexcept {}
void await_resume() noexcept {}
};
struct suspend_never {
bool await_ready() noexcept { return true; }
void await_suspend(coroutine_handle<>) noexcept {}
void await_resume() noexcept {}
};
} // namespace std
#endif // STD_COROUTINE_H