make sync_wait[_with_variant] available in std::this_thread when STDEXEC is std::execution

include/exec/any_sender_of.hpp

@@ -855,7 +855,7 @@ namespace exec {
       STDEXEC::inplace_stop_source __stop_source_{};
       using __stop_callback = typename STDEXEC::stop_token_of_t<
         STDEXEC::env_of_t<_Receiver>
-      >::template callback_type<__forward_stop_request>;
+      >::template callback_type<STDEXEC::__forward_stop_request>;
       std::optional<__stop_callback> __on_stop_{};
     };
 

include/exec/start_now.hpp

@@ -188,7 +188,7 @@ namespace exec {
 
     struct start_now_t {
       template <
-        STDEXEC::queryable _Env,
+        STDEXEC::__queryable _Env,
         exec::__scope::__async_scope _AsyncScope,
         STDEXEC::sender... _Sender
       >

include/exec/task.hpp

@@ -334,7 +334,7 @@ namespace exec {
 
      private:
       using __scheduler_t =
-        __query_result_or_t<get_scheduler_t, _Context, STDEXEC::inline_scheduler>;
+        __call_result_or_t<get_scheduler_t, STDEXEC::inline_scheduler, _Context>;
 
       struct __final_awaitable {
         static constexpr auto await_ready() noexcept -> bool {

include/stdexec/__detail/__completion_behavior.hpp

@@ -95,50 +95,45 @@ namespace STDEXEC {
   //////////////////////////////////////////////////////////////////////////////////////////
   // get_completion_behavior: A sender can define this attribute to describe the sender's
   // completion behavior
-  namespace __queries {
-    template <__completion_tag _Tag>
-    struct get_completion_behavior_t {
-     private:
-      template <class _Attrs, class... _Env>
-      STDEXEC_ATTRIBUTE(always_inline, host, device)
-      static constexpr auto __validate() noexcept {
-        using __result_t = __member_query_result_t<_Attrs, get_completion_behavior_t, _Env...>;
-        static_assert(
-          __nothrow_member_queryable_with<_Attrs, get_completion_behavior_t, _Env...>,
-          "The get_completion_behavior query must be noexcept.");
-        static_assert(
-          __std::convertible_to<__result_t, completion_behavior::behavior>,
-          "The get_completion_behavior query must return one of the static member variables in "
-          "execution::completion_behavior.");
-        return __result_t{};
-      }
+  template <__completion_tag _Tag>
+  struct get_completion_behavior_t {
+   private:
+    template <class _Attrs, class... _Env>
+    STDEXEC_ATTRIBUTE(always_inline, host, device)
+    static constexpr auto __validate() noexcept {
+      using __result_t = __member_query_result_t<_Attrs, get_completion_behavior_t, _Env...>;
+      static_assert(
+        __nothrow_member_queryable_with<_Attrs, get_completion_behavior_t, _Env...>,
+        "The get_completion_behavior query must be noexcept.");
+      static_assert(
+        __std::convertible_to<__result_t, completion_behavior::behavior>,
+        "The get_completion_behavior query must return one of the static member variables in "
+        "execution::completion_behavior.");
+      return __result_t{};
+    }
 
-     public:
-      template <class _Sig>
-      static inline constexpr get_completion_behavior_t (*signature)(_Sig) = nullptr;
+   public:
+    template <class _Sig>
+    static inline constexpr get_completion_behavior_t (*signature)(_Sig) = nullptr;
 
-      template <class _Attrs, class... _Env>
-      STDEXEC_ATTRIBUTE(nodiscard, always_inline, host, device)
-      constexpr auto operator()(const _Attrs&, const _Env&...) const noexcept {
-        if constexpr (
-          __member_queryable_with<const _Attrs&, get_completion_behavior_t<_Tag>, _Env...>) {
-          return __validate<_Attrs, _Env...>();
-        } else if constexpr (__member_queryable_with<
-                               const _Attrs&,
-                               get_completion_behavior_t<_Tag>
-                             >) {
-          return __validate<_Attrs>();
-        } else {
-          return completion_behavior::unknown;
-        }
+    template <class _Attrs, class... _Env>
+    STDEXEC_ATTRIBUTE(nodiscard, always_inline, host, device)
+    constexpr auto operator()(const _Attrs&, const _Env&...) const noexcept {
+      if constexpr (
+        __member_queryable_with<const _Attrs&, get_completion_behavior_t<_Tag>, _Env...>) {
+        return __validate<_Attrs, _Env...>();
+      } else if constexpr (__member_queryable_with<const _Attrs&, get_completion_behavior_t<_Tag>>) {
+        return __validate<_Attrs>();
+      } else {
+        return completion_behavior::unknown;
       }
+    }
 
-      STDEXEC_ATTRIBUTE(nodiscard, always_inline, host, device)
-      static constexpr auto query(forwarding_query_t) noexcept -> bool {
-        return true;
-      }
-    };
-  } // namespace __queries
+    STDEXEC_ATTRIBUTE(nodiscard, always_inline, host, device)
+    static constexpr auto query(forwarding_query_t) noexcept -> bool {
+      return true;
+    }
+  };
 
   [[deprecated("use STDEXEC::completion_behavior::weakest instead")]]
   inline constexpr const auto& min = completion_behavior::weakest;

include/stdexec/__detail/__config.hpp

@@ -179,7 +179,9 @@
 #endif
 
 STDEXEC_NAMESPACE_STD_BEGIN
-namespace execution {
+namespace execution::system_context_replaceability {
+}
+namespace this_thread {
 }
 STDEXEC_NAMESPACE_STD_END
 
@@ -207,6 +209,18 @@ STDEXEC_NAMESPACE_STD_END
 #  error stdexec cannot be defined directly in namespace std, but a namespace nested inside std is allowed.
 #endif
 
+// clang-format off
+#if STDEXEC_NAMESPACE_IS_WITHIN_STD()
+#  define STDEXEC_P2300_NAMESPACE_BEGIN(...)   STDEXEC_NAMESPACE_STD_BEGIN __VA_OPT__(namespace __VA_ARGS__ {)
+#  define STDEXEC_P2300_NAMESPACE_END(...)     __VA_OPT__(}) STDEXEC_NAMESPACE_STD_END
+#  define STDEXEC_P2300_DEPRECATED_SYMBOL(...) using __VA_ARGS__;
+#else
+#  define STDEXEC_P2300_NAMESPACE_BEGIN(...)   namespace STDEXEC {
+#  define STDEXEC_P2300_NAMESPACE_END(...)     }
+#  define STDEXEC_P2300_DEPRECATED_SYMBOL(...)
+#endif
+// clang-format on
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 #if __cpp_impl_coroutine >= 2019'02L && __cpp_lib_coroutine >= 2019'02L
 #  include <coroutine> // IWYU pragma: keep

include/stdexec/__detail/__debug.hpp

@@ -29,13 +29,11 @@
 namespace STDEXEC {
   /////////////////////////////////////////////////////////////////////////////
   // Some utilities for debugging senders
-  namespace __queries {
-    struct __debug_env_t : __query<__debug_env_t> {
-      static constexpr auto query(forwarding_query_t) noexcept -> bool {
-        return true;
-      }
-    };
-  } // namespace __queries
+  struct __debug_env_t : __query<__debug_env_t> {
+    static constexpr auto query(forwarding_query_t) noexcept -> bool {
+      return true;
+    }
+  };
 
   namespace __debug {
     struct _COMPLETION_SIGNATURES_MISMATCH_ { };
@@ -59,7 +57,7 @@ namespace STDEXEC {
     }
 
     template <class _Env>
-    using __env_t = env<prop<__queries::__debug_env_t, bool>, _Env>;
+    using __env_t = env<prop<__debug_env_t, bool>, _Env>;
 
     template <class _CvSender, class _Env, class... _Sigs>
     struct __receiver {