From 1a3ba6eff9b5472db14ecd0147b7907f98b62112 Mon Sep 17 00:00:00 2001
From: Auriane R <aurianer@cscs.ch>
Date: Tue, 4 Oct 2022 11:07:24 +0200
Subject: [PATCH 1/2] Add failing test with const_reference_sender

---
 .../tests/unit/algorithm_let_value.cpp         | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/libs/pika/execution/tests/unit/algorithm_let_value.cpp b/libs/pika/execution/tests/unit/algorithm_let_value.cpp
index be56f87abd..59edfaa6c3 100644
--- a/libs/pika/execution/tests/unit/algorithm_let_value.cpp
+++ b/libs/pika/execution/tests/unit/algorithm_let_value.cpp
@@ -98,6 +98,24 @@ int main()
         PIKA_TEST(let_value_callback_called);
     }
 
+    {
+        std::atomic<bool> set_value_called{false};
+        std::atomic<bool> let_value_callback_called{false};
+        int x = 42;
+        auto s1 = const_reference_sender<int>{x};
+        auto s2 = ex::let_value(std::move(s1), [&](auto& x) {
+            PIKA_TEST_EQ(x, 42);
+            let_value_callback_called = true;
+            return ex::just(x);
+        });
+        auto f = [](int x) { PIKA_TEST_EQ(x, 42); };
+        auto r = callback_receiver<decltype(f)>{f, set_value_called};
+        auto os = ex::connect(std::move(s2), std::move(r));
+        ex::start(os);
+        PIKA_TEST(set_value_called);
+        PIKA_TEST(let_value_callback_called);
+    }
+
     // operator| overload
     {
         std::atomic<bool> set_value_called{false};

From 46e53ba27f9b675fef4fdae8884356001eb73ae5 Mon Sep 17 00:00:00 2001
From: Auriane R <aurianer@cscs.ch>
Date: Tue, 4 Oct 2022 12:16:54 +0200
Subject: [PATCH 2/2] Attempt to fix const ref handling

---
 .../pika/execution/algorithms/let_value.hpp   | 22 +++++++++++++------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/libs/pika/execution/include/pika/execution/algorithms/let_value.hpp b/libs/pika/execution/include/pika/execution/algorithms/let_value.hpp
index 730f121889..eca49eb971 100644
--- a/libs/pika/execution/include/pika/execution/algorithms/let_value.hpp
+++ b/libs/pika/execution/include/pika/execution/algorithms/let_value.hpp
@@ -47,12 +47,19 @@ namespace pika::let_value_detail {
             predecessor_sender;
         PIKA_NO_UNIQUE_ADDRESS std::decay_t<F> f;
 
+        template <typename Tuple>
+        struct predecessor_value_types_helper
+        {
+            using type = pika::util::detail::transform_t<Tuple, std::decay>;
+        };
+
         // Type of the potential values returned from the predecessor sender
         template <template <typename...> class Tuple,
             template <typename...> class Variant>
-        using predecessor_value_types =
-            typename pika::execution::experimental::sender_traits<std::decay_t<
-                PredecessorSender>>::template value_types<Tuple, Variant>;
+        using predecessor_value_types = pika::util::detail::transform_t<
+            typename pika::execution::experimental::sender_traits<
+                PredecessorSender>::template value_types<Tuple, Variant>,
+            predecessor_value_types_helper>;
 
         template <typename Tuple>
         struct successor_sender_types_helper;
@@ -268,9 +275,9 @@ namespace pika::let_value_detail {
                 {
                     pika::detail::try_catch_exception_ptr(
                         [&]() {
-                            op_state.predecessor_ts
-                                .template emplace<std::tuple<Ts...>>(
-                                    PIKA_FORWARD(Ts, ts)...);
+                            op_state.predecessor_ts.template emplace<
+                                std::tuple<std::decay_t<Ts>...>>(
+                                PIKA_FORWARD(Ts, ts)...);
                             pika::detail::visit(
                                 set_value_visitor{PIKA_MOVE(receiver),
                                     PIKA_MOVE(f), op_state},
@@ -287,7 +294,8 @@ namespace pika::let_value_detail {
                     pika::execution::experimental::set_value_t,
                     let_value_predecessor_receiver&& r, Ts&&... ts) noexcept
                     -> decltype(std::declval<predecessor_ts_type>()
-                                    .template emplace<std::tuple<Ts...>>(
+                                    .template emplace<
+                                        std::tuple<std::decay_t<Ts>...>>(
                                         PIKA_FORWARD(Ts, ts)...),
                         void())
                 {