Merge pull request NVIDIA#1454 from maikel/any-sender-improve-overloads

Relax overload resolution of any receivers completion functions

Author: ericniebler

include/exec/any_sender_of.hpp

@@ -439,9 +439,7 @@ namespace exec {
         (*__other.__vtable_)(__copy_construct, this, __other);
       }
 
-      auto operator=(const __t& __other) -> __t&
-        requires(_Copyable)
-      {
+      auto operator=(const __t& __other) -> __t& requires(_Copyable) {
         if (&__other != this) {
           __t tmp(__other);
           *this = std::move(tmp);
@@ -615,6 +613,7 @@ namespace exec {
           , public __query_vfun<_Queries>... {
          public:
           using __query_vfun<_Queries>::operator()...;
+          using __any_::__rcvr_vfun<_Sigs>::operator()...;
 
          private:
           template <class _Rcvr>
@@ -674,24 +673,21 @@ namespace exec {
         }
 
         template <class... _As>
-          requires __one_of<set_value_t(_As...), _Sigs...>
+          requires __callable<__vtable_t, void*, set_value_t, _As...>
         void set_value(_As&&... __as) noexcept {
-          const __any_::__rcvr_vfun<set_value_t(_As...)>* __vfun = __env_.__vtable_;
-          (*__vfun->__complete_)(__env_.__rcvr_, static_cast<_As&&>(__as)...);
+          (*__env_.__vtable_)(__env_.__rcvr_, set_value_t(), static_cast<_As&&>(__as)...);
         }
 
         template <class _Error>
-          requires __one_of<set_error_t(_Error), _Sigs...>
+          requires __callable<__vtable_t, void*, set_error_t, _Error>
         void set_error(_Error&& __err) noexcept {
-          const __any_::__rcvr_vfun<set_error_t(_Error)>* __vfun = __env_.__vtable_;
-          (*__vfun->__complete_)(__env_.__rcvr_, static_cast<_Error&&>(__err));
+          (*__env_.__vtable_)(__env_.__rcvr_, set_error_t(), static_cast<_Error&&>(__err));
         }
 
         void set_stopped() noexcept
-          requires __one_of<set_stopped_t(), _Sigs...>
+          requires __callable<__vtable_t, void*, set_stopped_t>
         {
-          const __any_::__rcvr_vfun<set_stopped_t()>* __vfun = __env_.__vtable_;
-          (*__vfun->__complete_)(__env_.__rcvr_);
+          (*__env_.__vtable_)(__env_.__rcvr_, set_stopped_t());
         }
 
         auto get_env() const noexcept -> const __env_t& {

include/stdexec/__detail/__receiver_ref.hpp

@@ -30,16 +30,16 @@ namespace stdexec { namespace __any_ {
 
   template <class _Tag, class... _Args>
   struct __rcvr_vfun<_Tag(_Args...)> {
-    void (*__complete_)(void*, _Args&&...) noexcept;
+    void (*__complete_)(void*, _Args...) noexcept;
 
-    void operator()(void* __obj, _Tag, _Args&&... __args) const noexcept {
+    void operator()(void* __obj, _Tag, _Args... __args) const noexcept {
       __complete_(__obj, static_cast<_Args&&>(__args)...);
     }
   };
 
   template <class _GetReceiver = std::identity, class _Obj, class _Tag, class... _Args>
   constexpr auto __rcvr_vfun_fn(_Obj*, _Tag (*)(_Args...)) noexcept {
-    return +[](void* __ptr, _Args&&... __args) noexcept {
+    return +[](void* __ptr, _Args... __args) noexcept {
       _Obj* __obj = static_cast<_Obj*>(__ptr);
       _Tag()(std::move(_GetReceiver()(*__obj)), static_cast<_Args&&>(__args)...);
     };
@@ -95,16 +95,20 @@ namespace stdexec { namespace __any_ {
     }
 
     template <class... _As>
+      requires __callable<__receiver_vtable_for<_Sigs, _Env>, void*, set_value_t, _As...>
     void set_value(_As&&... __as) noexcept {
       (*__vtable_)(__op_state_, set_value_t(), static_cast<_As&&>(__as)...);
     }
 
     template <class _Error>
+      requires __callable<__receiver_vtable_for<_Sigs, _Env>, void*, set_error_t, _Error>
     void set_error(_Error&& __err) noexcept {
       (*__vtable_)(__op_state_, set_error_t(), static_cast<_Error&&>(__err));
     }
 
-    void set_stopped() noexcept {
+    void set_stopped() noexcept
+      requires __callable<__receiver_vtable_for<_Sigs, _Env>, void*, set_stopped_t>
+    {
       (*__vtable_)(__op_state_, set_stopped_t());
     }
 

test/exec/test_any_sender.cpp

@@ -259,10 +259,9 @@ namespace {
   TEST_CASE("sync_wait works on any_sender_of", "[types][any_sender]") {
     int value = 0;
     any_sender_of<set_value_t()> sender = just(42) | then([&](int v) noexcept { value = v; });
-    CHECK(
-      std::same_as<
-        completion_signatures_of_t<any_sender_of<set_value_t()>>,
-        completion_signatures<set_value_t()>>);
+    CHECK(std::same_as<
+          completion_signatures_of_t<any_sender_of<set_value_t()>>,
+          completion_signatures<set_value_t()>>);
     sync_wait(std::move(sender));
     CHECK(value == 42);
   }
@@ -276,10 +275,9 @@ namespace {
 
   TEST_CASE("sync_wait returns value", "[types][any_sender]") {
     any_sender_of<set_value_t(int)> sender = just(21) | then([&](int v) noexcept { return 2 * v; });
-    CHECK(
-      std::same_as<
-        completion_signatures_of_t<any_sender_of<set_value_t(int)>>,
-        completion_signatures<set_value_t(int)>>);
+    CHECK(std::same_as<
+          completion_signatures_of_t<any_sender_of<set_value_t(int)>>,
+          completion_signatures<set_value_t(int)>>);
     auto [value1] = *sync_wait(std::move(sender));
     CHECK(value1 == 42);
   }
@@ -330,6 +328,23 @@ namespace {
     }
   }
 
+  template <class... Vals>
+  using my_stoppable_sender_of =
+    any_sender_of<set_value_t(Vals)..., set_error_t(std::exception_ptr), set_stopped_t()>;
+
+  TEST_CASE("any_sender uses overload rules for completion signatures", "[types][any_sender]") {
+    auto split_sender = split(just(42));
+    static_assert(sender_of<decltype(split_sender), set_error_t(const std::exception_ptr&)>);
+    static_assert(sender_of<decltype(split_sender), set_value_t(const int&)>);
+    my_stoppable_sender_of<int> sender = split_sender;
+
+    auto [value] = *sync_wait(std::move(sender));
+    CHECK(value == 42);
+
+    sender = just(21) | then([&](int) -> int { throw 420; });
+    CHECK_THROWS_AS(sync_wait(std::move(sender)), int);
+  }
+
   class stopped_token {
    private:
     bool stopped_{true};