updated the TODO (primarily to create a PR)

README.md

@@ -36,7 +36,7 @@ e.g.:
 
 | Library | Linux | MacOS | Windows |
 | ------- | ----- | ----- | ------- |
-| build | ![Linux build status](https://github.com/dietmarkuehl/beman-execution/actions/workflows/linux.yml/badge.svg) | ![MacOS build status](https://github.com/dietmarkuehl/beman-execution/actions/workflows/macos.yml/badge.svg) | ![Window build status](https://github.com/dietmarkuehl/beman-execution/actions/workflows/windows.yml/badge.svg) |
+| build | ![Linux build status](https://github.com/beman-project/Execution26/actions/workflows/linux.yml/badge.svg) | ![MacOS build status](https://github.com/beman-project/Execution26/actions/workflows/macos.yml/badge.svg) | ![Window build status](https://github.com/beman-project/Execution26/actions/workflows/windows.yml/badge.svg) |
 
 You can just use `make` in the current directory. It will invoke `cmake`,
 build the code, and run tests. To have more control over the build-process

docs/TODO.json

@@ -4,6 +4,7 @@
     "execution.queries": { "code":true, "test":true, "doc":true, "comment":"empty" },
     "execution.queryable": { "code":true, "test":true, "doc":true, "comment":"empty" },
     "execution.queryable.general]": { "code":true, "test":true, "doc":false, "comment":"nothing testable" },
+    "execution.forwarding_query": { "code":true, "test":true, "doc":false },
     "execution.queryable.concepts": { "code":true, "test":true, "doc":false },
     "execution.receivers": { "code":true, "test":true, "doc":true, "comment":"empty" },
     "execution.senders": { "code":true, "test":true, "doc":true, "comment":"empty" },

docs/TODO.md

@@ -49,7 +49,7 @@
 | [[execution-async.ops](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution-async.ops)] | 🔴 | 🔴 | 🔴 |  |
 | [[execution.syn](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.syn)] | 🔴 | 🔴 | 🔴 |  |
 | [[execution.queries](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.queries)] | ✅ | ✅ | ✅ | empty |
-| [[execution.forwarding_query](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.forwarding_query)] | 🔴 | 🔴 | 🔴 |  |
+| [[execution.forwarding_query](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.forwarding_query)] | ✅ | ✅ | 🔴 |  |
 | [[execution.get_allocator](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.get_allocator)] | 🔴 | 🔴 | 🔴 |  |
 | [[execution.get_stop_token](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.get_stop_token)] | 🔴 | 🔴 | 🔴 |  |
 | [[execution.environment.get_env](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.environment.get_env)] | 🔴 | 🔴 | 🔴 |  |
@@ -64,7 +64,7 @@
 | [[execution.receivers.set_value](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.receivers.set_value)] | ✅ | ✅ | 🔴 |  |
 | [[execution.receivers.set_error](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.receivers.set_error)] | ✅ | ✅ | 🔴 |  |
 | [[execution.receivers.set_stopped](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.receivers.set_stopped)] | ✅ | ✅ | 🔴 |  |
-| [[execution.opstate](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.opstate)] | 🔴 | 🔴 | 🔴 |  |
+| [[execution.opstate](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.opstate)] | ✅ | ✅ | 🔴 |  |
 | [[execution.opstate.start](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.opstate.start)] | ✅ | ✅ | 🔴 |  |
 | [[execution.senders](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.senders)] | ✅ | ✅ | ✅ | empty |
 | [[execution.senders.general](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2300r10.html#execution.senders.general)] | 🔴 | 🔴 | 🔴 |  |

docs/questions.md

@@ -12,3 +12,6 @@ likely observable.
 - [exec.general] use "Mandates: err != exception_ptr() is true."
     However, the condition can only be determined at run-time =>
     The "Mandates" should be "Precondition".
+- [exec.fwd.env] states "Mandates: ... is a core constant expression if
+    `q` is a core constant expression": I don't know how to possibly
+    implement that.

include/Beman/Execution26/detail/forwarding_query.hpp

@@ -0,0 +1,37 @@
+// include/Beman/Execution26/detail/forwarding_query.hpp              -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef INCLUDED_BEMAN_EXECUTION26_DETAIL_FORWARDING_QUERY
+#define INCLUDED_BEMAN_EXECUTION26_DETAIL_FORWARDING_QUERY
+
+#include <concepts>
+#include <utility>
+
+// ----------------------------------------------------------------------------
+
+namespace Beman::Execution26
+{
+    struct forwarding_query_t
+    {
+        template <typename Object>
+            requires requires(Object&& object, forwarding_query_t const& query)
+            {
+                 { ::std::forward<Object>(object).query(query) } noexcept -> ::std::same_as<bool>;
+            }
+        constexpr auto operator()(Object&& object) const noexcept -> bool
+        {
+            return ::std::forward<Object>(object).query(*this);
+        }
+        template <typename Object>
+        constexpr auto operator()(Object&&) const noexcept -> bool
+        {
+            return ::std::derived_from<Object, ::Beman::Execution26::forwarding_query_t>;
+        }
+    };
+
+    inline constexpr forwarding_query_t forwarding_query{};
+}
+
+// ----------------------------------------------------------------------------
+
+#endif

src/Beman/Execution26/tests/CMakeLists.txt

@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 list(APPEND execution_tests
+    exec-fwd-env.pass
     exec-opstate.pass
     exec-opstate-start.pass
     allocator-requirements-general.pass

src/Beman/Execution26/tests/exec-fwd-env.pass.cpp

@@ -0,0 +1,80 @@
+// src/Beman/Execution26/tests/exec-fwd-env.pass.cpp                  -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <Beman/Execution26/detail/forwarding_query.hpp>
+#include <Beman/Execution26/execution.hpp>
+#include <test/execution.hpp>
+#include <concepts>
+
+// ----------------------------------------------------------------------------
+
+namespace
+{
+    struct derived
+        : test_std::forwarding_query_t
+    {
+    };
+
+    template <bool Noexcept = true, typename Result = bool, Result Value = true>
+    struct static_query
+    {
+        constexpr auto query(test_std::forwarding_query_t) noexcept(Noexcept) -> Result
+        {
+            return Value;
+        }
+    };
+
+    struct rvalue_query
+    {
+        constexpr auto query(test_std::forwarding_query_t) && noexcept -> bool
+        {
+            return true;
+        }
+    };
+
+    struct const_query
+    {
+        constexpr auto query(test_std::forwarding_query_t&&) noexcept -> bool = delete;
+        constexpr auto query(test_std::forwarding_query_t&) noexcept -> bool = delete;
+        constexpr auto query(test_std::forwarding_query_t const&) noexcept -> bool
+        {
+            return true;
+        }
+    };
+
+    struct dynamic_query
+    {
+        bool value{true};
+        constexpr auto query(test_std::forwarding_query_t) && noexcept -> bool
+        {
+            return value;
+        }
+    };
+}
+
+auto main(int ac, char*[]) -> int
+{
+    static_assert(std::same_as<test_std::forwarding_query_t const,
+                               decltype(test_std::forwarding_query)>);
+
+    static_assert(not test_std::forwarding_query(0));
+    static_assert(test_std::forwarding_query(derived()));
+    static_assert(test_std::forwarding_query(static_query<>()));
+    static_assert(not test_std::forwarding_query(static_query<false>()));
+    static_assert(not test_std::forwarding_query(static_query<true, int>()));
+    static_assert(not test_std::forwarding_query(static_query<true, bool, false>()));
+
+    static_assert(test_std::forwarding_query(rvalue_query()));
+    rvalue_query rq{};
+    static_assert(not test_std::forwarding_query(rq));
+    rvalue_query crq{};
+    static_assert(not test_std::forwarding_query(crq));
+
+    static_assert(test_std::forwarding_query(const_query()));
+
+    static_assert(test_std::forwarding_query(dynamic_query()));
+    static_assert(test_std::forwarding_query(dynamic_query{true}));
+    static_assert(not test_std::forwarding_query(dynamic_query{false}));
+    assert(test_std::forwarding_query(dynamic_query{ac == 1}));
+    assert(not test_std::forwarding_query(dynamic_query{ac != 1}));
+}