Index: cfe/trunk/lib/Sema/SemaCoroutine.cpp =================================================================== --- cfe/trunk/lib/Sema/SemaCoroutine.cpp +++ cfe/trunk/lib/Sema/SemaCoroutine.cpp @@ -841,6 +841,19 @@ E = R.get(); } + // Move the return value if we can + if (E) { + auto NRVOCandidate = this->getCopyElisionCandidate(E->getType(), E, CES_AsIfByStdMove); + if (NRVOCandidate) { + InitializedEntity Entity = + InitializedEntity::InitializeResult(Loc, E->getType(), NRVOCandidate); + ExprResult MoveResult = this->PerformMoveOrCopyInitialization( + Entity, NRVOCandidate, E->getType(), E); + if (MoveResult.get()) + E = MoveResult.get(); + } + } + // FIXME: If the operand is a reference to a variable that's about to go out // of scope, we should treat the operand as an xvalue for this overload // resolution. Index: cfe/trunk/test/SemaCXX/coroutine-rvo.cpp =================================================================== --- cfe/trunk/test/SemaCXX/coroutine-rvo.cpp +++ cfe/trunk/test/SemaCXX/coroutine-rvo.cpp @@ -0,0 +1,69 @@ +// RUN: %clang_cc1 -triple x86_64-apple-darwin9 %s -stdlib=libc++ -std=c++1z -fcoroutines-ts -fsyntax-only + +namespace std::experimental { +template struct coroutine_handle { + coroutine_handle() = default; + static coroutine_handle from_address(void *) noexcept; +}; + +template <> struct coroutine_handle { + static coroutine_handle from_address(void *) noexcept; + coroutine_handle() = default; + template + coroutine_handle(coroutine_handle) noexcept; +}; + +template +struct void_t_imp { + using type = void; +}; +template +using void_t = typename void_t_imp::type; + +template +struct traits_sfinae_base {}; + +template +struct traits_sfinae_base> { + using promise_type = typename T::promise_type; +}; + +template +struct coroutine_traits : public traits_sfinae_base {}; +} + +struct suspend_never { + bool await_ready() noexcept; + void await_suspend(std::experimental::coroutine_handle<>) noexcept; + void await_resume() noexcept; +}; + +struct MoveOnly { + MoveOnly() {}; + MoveOnly(const MoveOnly&) = delete; + MoveOnly(MoveOnly&&) noexcept {}; + ~MoveOnly() {}; +}; + +template +struct task { + struct promise_type { + auto initial_suspend() { return suspend_never{}; } + auto final_suspend() { return suspend_never{}; } + auto get_return_object() { return task{}; } + static void unhandled_exception() {} + void return_value(T&& value) {} + }; +}; + +task f() { + MoveOnly value; + co_return value; +} + +int main() { + f(); + return 0; +} + +// expected-no-diagnostics