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use the updated env when computing the final sender's completions #1907

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Merged
ericniebler merged 1 commit into from
Mar 3, 2026
Merged

use the updated env when computing the final sender's completions #1907

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72 changes: 38 additions & 34 deletions include/stdexec/__detail/__finally.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -44,29 +44,28 @@ namespace STDEXEC

struct __finally_t
{
template <STDEXEC::sender _Initial, STDEXEC::sender _Final>
template <sender _Initial, sender _Final>
constexpr auto operator()(_Initial&& __initial, _Final&& __final) const //
-> STDEXEC::__well_formed_sender auto
-> __well_formed_sender auto
{
return STDEXEC::__make_sexpr<__finally_t>({},
static_cast<_Initial&&>(__initial),
static_cast<_Final&&>(__final));
return __make_sexpr<__finally_t>({},
static_cast<_Initial&&>(__initial),
static_cast<_Final&&>(__final));
}

template <STDEXEC::sender _Final>
template <sender _Final>
STDEXEC_ATTRIBUTE(always_inline)
constexpr auto operator()(_Final&& __final) const
{
return STDEXEC::__closure(*this, static_cast<_Final&&>(__final));
return __closure(*this, static_cast<_Final&&>(__final));
}

template <class _Sender>
static constexpr auto
transform_sender(STDEXEC::set_value_t, _Sender&& __sndr, STDEXEC::__ignore)
static constexpr auto transform_sender(set_value_t, _Sender&& __sndr, __ignore)
{
auto& [__tag, __ign, __initial, __final] = __sndr;
return STDEXEC::__final::__sender{STDEXEC::__forward_like<_Sender>(__initial), //
STDEXEC::__forward_like<_Sender>(__final)};
return __final::__sender{STDEXEC::__forward_like<_Sender>(__initial), //
STDEXEC::__forward_like<_Sender>(__final)};
}
};

Expand Down Expand Up @@ -122,19 +121,27 @@ namespace STDEXEC
template <class _Receiver, class _Tuple>
constexpr void operator()(_Receiver& __rcvr, _Tuple&& __tuple) noexcept
{
STDEXEC::__apply(__applier{}, static_cast<_Tuple&&>(__tuple), __rcvr);
__apply(__applier{}, static_cast<_Tuple&&>(__tuple), __rcvr);
}
};

using __mk_secondary_env_t = __mk_secondary_env_t<set_value_t, set_error_t, set_stopped_t>;

template <class _CvInitialSender, class _ReceiverEnv>
using __env2_t = __call_result_t<__mk_secondary_env_t, _CvInitialSender, _ReceiverEnv>;

template <class _Env2, class _ReceiverEnv>
using __final_env_t = __join_env_t<_Env2 const &, __fwd_env_t<_ReceiverEnv>>;

template <class _ResultType, class _Receiver, class _Env2>
struct __final_receiver
{
using receiver_concept = receiver_t;
using __env2_t = __join_env_t<_Env2 const &, __fwd_env_t<env_of_t<_Receiver>>>;
using __env_t = __final_env_t<_Env2, env_of_t<_Receiver>>;

constexpr void set_value() noexcept
{
STDEXEC::__visit(__visitor{}, std::move(__opstate_->__result_), __opstate_->__rcvr_);
__visit(__visitor{}, std::move(__opstate_->__result_), __opstate_->__rcvr_);
}

template <class _Error>
Expand All @@ -150,7 +157,7 @@ namespace STDEXEC
}

[[nodiscard]]
constexpr auto get_env() const noexcept -> __env2_t
constexpr auto get_env() const noexcept -> __env_t
{
return __env::__join(__opstate_->__env2_, __fwd_env(STDEXEC::get_env(__opstate_->__rcvr_)));
}
Expand Down Expand Up @@ -214,28 +221,18 @@ namespace STDEXEC
template <class _CvFinalSender, class _ResultType, class _Receiver, class _Env2>
struct __initial_receiver;

template <class _CvInitialSender, class _CvFinalSender, class _Receiver, class _Env2>
template <class _CvInitialSender, class _CvFinalSender, class _Receiver>
using __final_opstate_t =
__final_opstate<_CvFinalSender,
__result_variant_t<_CvInitialSender, _CvFinalSender, _Receiver>,
_Receiver,
_Env2>;

using __mk_secondary_env_t =
STDEXEC::__mk_secondary_env_t<set_value_t, set_error_t, set_stopped_t>;

template <class _CvInitialSender, class _Receiver>
using __env2_t = __call_result_t<__mk_secondary_env_t, _CvInitialSender, env_of_t<_Receiver>>;
__env2_t<_CvInitialSender, env_of_t<_Receiver>>>;

template <class _CvInitialSender, class _CvFinalSender, class _Receiver>
struct __opstate
: __final_opstate_t<_CvInitialSender,
_CvFinalSender,
_Receiver,
__env2_t<_CvInitialSender, _Receiver>>
struct __opstate : __final_opstate_t<_CvInitialSender, _CvFinalSender, _Receiver>
{
using __env2_t = __final::__env2_t<_CvInitialSender, _Receiver>;
using __base_t = __final_opstate_t<_CvInitialSender, _CvFinalSender, _Receiver, __env2_t>;
using __env2_t = __final::__env2_t<_CvInitialSender, env_of_t<_Receiver>>;
using __base_t = __final_opstate_t<_CvInitialSender, _CvFinalSender, _Receiver>;
using __initial_results_t = __base_t::__results_t;

constexpr explicit __opstate(_CvInitialSender&& __initial,
Expand Down Expand Up @@ -303,17 +300,22 @@ namespace STDEXEC
__final_opstate<_CvFinalSender, _ResultType, _Receiver, _Env2>* __opstate_;
};

template <class _CvInitialSender, class _Env>
using __mk_final_env_t = __final_env_t<__env2_t<_CvInitialSender, _Env>, _Env>;

template <class _CvInitialSender, class _CvFinalSender, class... _Env>
consteval auto __get_completion_signatures()
{
STDEXEC_COMPLSIGS_LET(__initial_completions,
STDEXEC::get_completion_signatures<_CvInitialSender, _Env...>())
get_completion_signatures<_CvInitialSender, _Env...>())
{
using __initial_completions_t = decltype(__initial_completions);
auto __final_completions =
STDEXEC::get_completion_signatures<_CvFinalSender, __fwd_env_t<_Env>...>();
get_completion_signatures<_CvFinalSender, __mk_final_env_t<_CvInitialSender, _Env>...>();

if constexpr (!__sends<set_value_t, _CvFinalSender, __fwd_env_t<_Env>...>)
if constexpr (__never_sends<set_value_t,
_CvFinalSender,
__mk_final_env_t<_CvInitialSender, _Env>...>)
{
// If the finally sender doesn't have set_value completions, then we
// don't need to worry about the initial sender's value types not being
Expand All @@ -325,7 +327,9 @@ namespace STDEXEC
{},
__final_completions);
}
else if constexpr (!sender_of<_CvFinalSender, set_value_t(), __fwd_env_t<_Env>...>)
else if constexpr (!sender_of<_CvFinalSender,
set_value_t(),
__mk_final_env_t<_CvInitialSender, _Env>...>)
{
// If the finally sender has value completions other than set_value_t(), then
// throw a compilation error.
Expand Down