Merge pull request #1172 from NVIDIA/fix-sync-wait-with-variant-retur…

…n-type remove erroneous tuple in return type of `sync_wait_with_variant`
NVIDIA · Dec 16, 2023 · e8e27de · e8e27de
2 parents bc10e41 + 5433dcd
commit e8e27de
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Showing 2 changed files with 15 additions and 8 deletions.
diff --git a/include/stdexec/execution.hpp b/include/stdexec/execution.hpp
@@ -5532,6 +5532,10 @@ namespace stdexec {
     template <class _Sender>
     using __sync_wait_result_t = __mtry_eval<__sync_wait_result_impl, _Sender, __q<std::tuple>>;
 
+    template <class _Sender>
+    using __sync_wait_with_variant_result_t =
+      __mtry_eval<__sync_wait_result_impl, __result_of<into_variant, _Sender>, __q<__midentity>>;
+
     template <class... _Values>
     struct __state {
       using _Tuple = std::tuple<_Values...>;
@@ -5605,7 +5609,7 @@ namespace stdexec {
 
     template <class _Sender>
     struct __variant_for {
-      using __t = __sync_wait_result_t<__result_of<into_variant, _Sender>>;
+      using __t = __sync_wait_with_variant_result_t<_Sender>;
     };
     template <class _Sender>
     using __variant_for_t = __t<__variant_for<_Sender>>;
@@ -5762,7 +5766,10 @@ namespace stdexec {
       template <class _Sender>
         requires __callable<sync_wait_t, __result_of<into_variant, _Sender>>
       auto apply_sender(_Sender&& __sndr) const -> std::optional<__variant_for_t<_Sender>> {
-        return sync_wait_t()(into_variant((_Sender&&) __sndr));
+        if (auto __opt_values = sync_wait_t()(into_variant((_Sender&&) __sndr))) {
+          return std::move(std::get<0>(*__opt_values));
+        }
+        return std::nullopt;
       }
     };
   } // namespace __sync_wait

diff --git a/test/stdexec/algos/consumers/test_sync_wait.cpp b/test/stdexec/algos/consumers/test_sync_wait.cpp
@@ -281,7 +281,7 @@ namespace {
   using my_transfered_multi_value_sender_t =
     decltype(ex::transfer(my_multi_value_sender_t{}, inline_scheduler{}));
 
-  optional<std::tuple<std::variant<std::tuple<std::string>, std::tuple<int>>>> tag_invoke(
+  optional<std::variant<std::tuple<std::string>, std::tuple<int>>> tag_invoke(
     decltype(sync_wait_with_variant),
     inline_scheduler sched,
     my_transfered_multi_value_sender_t&& s) {
@@ -294,7 +294,7 @@ namespace {
     return {res};
   }
 
-  optional<std::tuple<std::variant<std::tuple<std::string>, std::tuple<int>>>>
+  optional<std::variant<std::tuple<std::string>, std::tuple<int>>>
     tag_invoke(decltype(sync_wait_with_variant), my_multi_value_sender_t s) {
     CHECK(s.str_ == "hello_multi");
     return {std::string{"ciao_multi"}};
@@ -306,21 +306,21 @@ namespace {
     // The customization will return a different value
     auto snd = ex::transfer(my_multi_value_sender_t{"hello_multi"}, inline_scheduler{});
     auto snd2 = ex::transfer_just(inline_scheduler{}, std::string{"hello"});
-    optional<std::tuple<std::variant<std::tuple<std::string>, std::tuple<int>>>> res =
+    optional<std::variant<std::tuple<std::string>, std::tuple<int>>> res =
       sync_wait_with_variant(std::move(snd));
     CHECK(res.has_value());
-    CHECK(std::get<0>(std::get<0>(res.value())) == std::make_tuple(std::string{"hallo_multi"}));
+    CHECK(std::get<0>(std::get<0>(res.value())) == std::string{"hallo_multi"});
   }
 
   TEST_CASE(
     "sync_wait_with_variant can be customized without scheduler",
     "[consumers][sync_wait_with_variant]") {
     // The customization will return a different value
     my_multi_value_sender_t snd{std::string{"hello_multi"}};
-    optional<std::tuple<std::variant<std::tuple<std::string>, std::tuple<int>>>> res =
+    optional<std::variant<std::tuple<std::string>, std::tuple<int>>> res =
       sync_wait_with_variant(std::move(snd));
     CHECK(res.has_value());
-    CHECK(std::get<0>(std::get<0>(res.value())) == std::make_tuple(std::string{"ciao_multi"}));
+    CHECK(std::get<0>(std::get<0>(res.value())) == std::string{"ciao_multi"});
   }
 
   template <class... Ts>