add test_scheduler to support marble tests

include/exec/sequence/ignore_all_values.hpp

@@ -317,8 +317,7 @@ namespace exec {
       static constexpr auto connect =
         []<class _Sender, receiver _Receiver>(_Sender&& __sndr, _Receiver __rcvr) noexcept(
           __nothrow_callable<__sexpr_apply_t, _Sender, __connect_fn<_Receiver>>)
-        -> __call_result_t<__sexpr_apply_t, _Sender, __connect_fn<_Receiver>>
-      {
+        -> __call_result_t<__sexpr_apply_t, _Sender, __connect_fn<_Receiver>> {
         static_assert(sender_expr_for<_Sender, ignore_all_values_t>);
         return __sexpr_apply(static_cast<_Sender&&>(__sndr), __connect_fn<_Receiver>{__rcvr});
       };

include/exec/sequence/merge_each.hpp

@@ -727,15 +727,21 @@ namespace exec {
 
       template <class _Sequence, class _Sender, class... _Env>
       struct __arg_of_t {
+
+        template <class... _Args>
+        static constexpr bool __valid_args = sizeof...(_Args) == 1
+                                          && (has_sequence_item_types<_Args, _Env...> && ...
+                                              && true);
+
         template <class... _Args>
-        using __f = stdexec::__meval<
-          stdexec::__if_c<
-            sizeof...(_Args) == 1 && (has_sequence_item_types<_Args, _Env...> && ...),
-            stdexec::__q<stdexec::__types>,
-            __value_completions_error<_Sequence, _Sender, _Env...>
-          >::template __f,
-          _Args...
+        using __checked_eval_t = stdexec::__if_c<
+          __valid_args<_Args...>,
+          stdexec::__types<_Args...>,
+          __value_completions_error<_Sequence, _Sender, _Env...>
         >;
+
+        template <class... _Args>
+        using __f = __checked_eval_t<_Args...>;
       };
 
       template <class _Sequence, class _Sender, class... _Env>

include/exec/sequence/transform_each.hpp

@@ -135,11 +135,14 @@ namespace exec {
 
       template <class... _Items>
       auto operator()(item_types<_Items...>*) -> decltype((
-        stdexec::__msuccess(), ..., __try_adaptor_for_item(static_cast<_Items*>(nullptr))));
+        stdexec::__msuccess(),
+        ...,
+        __try_adaptor_for_item(static_cast<_Items*>(nullptr))));
     };
 
     template <class _Adaptor, class _Items>
-    using __try_adaptor_calls_result_t = __call_result_t<__try_adaptor_calls_t<stdexec::__decay_t<_Adaptor>>, _Items>;
+    using __try_adaptor_calls_result_t =
+      __call_result_t<__try_adaptor_calls_t<stdexec::__decay_t<_Adaptor>>, _Items>;
 
     template <class _Adaptor, class _Items>
     concept __callable_adaptor_for = requires(_Items* __items) {
@@ -150,7 +153,7 @@ namespace exec {
       template <sender _Sequence, __sender_adaptor_closure _Adaptor>
       auto operator()(_Sequence&& __sndr, _Adaptor&& __adaptor) const
         noexcept(__nothrow_decay_copyable<_Sequence> && __nothrow_decay_copyable<_Adaptor>)
-        -> __well_formed_sequence_sender auto {
+          -> __well_formed_sequence_sender auto {
         return make_sequence_expr<transform_each_t>(
           static_cast<_Adaptor&&>(__adaptor), static_cast<_Sequence&&>(__sndr));
       }
@@ -166,8 +169,8 @@ namespace exec {
       using __completion_sigs_t = __sequence_completion_signatures_of_t<__child_of<_Self>, _Env...>;
 
       template <sender_expr_for<transform_each_t> _Self, class... _Env>
-      static auto
-        get_completion_signatures(_Self&&, _Env&&...) noexcept -> __completion_sigs_t<_Self, _Env...> {
+      static auto get_completion_signatures(_Self&&, _Env&&...) noexcept
+        -> __completion_sigs_t<_Self, _Env...> {
         return {};
       }
 
@@ -180,57 +183,61 @@ namespace exec {
         __item_types_of_t<__child_of<_Self>, _Env...>
       >;
 
-        template<class _Transform>
-        struct _TRANSFORM_EACH_ADAPTOR_INVOCATION_FAILED_ {};
+      template <class _Transform>
+      struct _TRANSFORM_EACH_ADAPTOR_INVOCATION_FAILED_ { };
 
-        template <sender_expr_for<transform_each_t> _Self, class... _Env>
-          requires (!__mvalid<__item_types_t, _Self, _Env...>)
-                && __mvalid<__item_types_of_t, __child_of<_Self>, _Env...>
-                && (!__callable_adaptor_for<
-                   __data_of<_Self>,
-                   __item_types_of_t<__child_of<_Self>, _Env...>
-                 >)
-        static auto get_item_types(_Self&&, _Env&&...) noexcept -> __mexception<
-          _TRANSFORM_EACH_ADAPTOR_INVOCATION_FAILED_<_Self>,
-          _WITH_SEQUENCE_<__child_of<_Self>>,
-          _WITH_ENVIRONMENT_<_Env...>,
-          _WITH_TYPE_<__try_adaptor_calls_result_t<
-            __data_of<_Self>,
-            __item_types_of_t<__child_of<_Self>, _Env...>>>>;
-
-      template<class _Transform>
-      struct _TRANSFORM_EACH_ITEM_TYPES_OF_THE_CHILD_ARE_INVALID_ {};
+      template <sender_expr_for<transform_each_t> _Self, class... _Env>
+        requires(!__mvalid<__item_types_t, _Self, _Env...>)
+             && __mvalid<__item_types_of_t, __child_of<_Self>, _Env...>
+             && (!__callable_adaptor_for<
+                 __data_of<_Self>,
+                 __item_types_of_t<__child_of<_Self>, _Env...>
+             >)
+      static auto get_item_types(_Self&&, _Env&&...) noexcept -> __mexception<
+        _TRANSFORM_EACH_ADAPTOR_INVOCATION_FAILED_<_Self>,
+        _WITH_SEQUENCE_<__child_of<_Self>>,
+        _WITH_ENVIRONMENT_<_Env...>,
+        _WITH_TYPE_<__try_adaptor_calls_result_t<
+          __data_of<_Self>,
+          __item_types_of_t<__child_of<_Self>, _Env...>
+        >>
+      >;
+
+      template <class _Transform>
+      struct _TRANSFORM_EACH_ITEM_TYPES_OF_THE_CHILD_ARE_INVALID_ { };
 
       template <sender_expr_for<transform_each_t> _Self, class... _Env>
-        requires (!__mvalid<__item_types_t, _Self, _Env...>)
-              && (!__mvalid<__item_types_of_t, __child_of<_Self>, _Env...>)
+        requires(!__mvalid<__item_types_t, _Self, _Env...>)
+             && (!__mvalid<__item_types_of_t, __child_of<_Self>, _Env...>)
       static auto get_item_types(_Self&&, _Env&&...) noexcept -> __mexception<
         _TRANSFORM_EACH_ITEM_TYPES_OF_THE_CHILD_ARE_INVALID_<_Self>,
         _WITH_SEQUENCE_<__child_of<_Self>>,
-        _WITH_ENVIRONMENT_<_Env...>>;
+        _WITH_ENVIRONMENT_<_Env...>
+      >;
 
-      template<class _Transform>
-      struct _TRANSFORM_EACH_ITEM_TYPES_CALCULATION_FAILED_ {};
+      template <class _Transform>
+      struct _TRANSFORM_EACH_ITEM_TYPES_CALCULATION_FAILED_ { };
 
       template <sender_expr_for<transform_each_t> _Self, class... _Env>
-        requires (!__mvalid<__item_types_t, _Self, _Env...>)
-              && __mvalid<__item_types_of_t, __child_of<_Self>, _Env...>
-              && __callable_adaptor_for<
+        requires(!__mvalid<__item_types_t, _Self, _Env...>)
+             && __mvalid<__item_types_of_t, __child_of<_Self>, _Env...>
+             && __callable_adaptor_for<
                   __data_of<_Self>,
                   __item_types_of_t<__child_of<_Self>, _Env...>
-                >
+             >
       static auto get_item_types(_Self&&, _Env&&...) noexcept -> __mexception<
         _TRANSFORM_EACH_ITEM_TYPES_CALCULATION_FAILED_<_Self>,
         _WITH_SEQUENCE_<__child_of<_Self>>,
-        _WITH_ENVIRONMENT_<_Env...>>;
+        _WITH_ENVIRONMENT_<_Env...>
+      >;
 
       template <sender_expr_for<transform_each_t> _Self, class... _Env>
         requires __mvalid<__item_types_t, _Self, _Env...>
               && __mvalid<__item_types_of_t, __child_of<_Self>, _Env...>
               && __callable_adaptor_for<
-                  __data_of<_Self>,
-                  __item_types_of_t<__child_of<_Self>, _Env...>
-                >
+                   __data_of<_Self>,
+                   __item_types_of_t<__child_of<_Self>, _Env...>
+              >
       static auto get_item_types(_Self&&, _Env&&...) noexcept -> __item_types_t<_Self, _Env...> {
         return {};
       }

include/exec/sequence_senders.hpp

@@ -211,7 +211,7 @@ namespace exec {
       tag_invocable<get_item_types_t, __tfx_sequence_t<_Sequence, _Env>, _Env>;
 
     template <class _Sequence, class _Env>
-    using __member_alias_t = typename __decay_t<__tfx_sequence_t<_Sequence, _Env>>::item_types;
+    using __member_alias_t = __decay_t<__tfx_sequence_t<_Sequence, _Env>>::item_types;
 
     template <class _Sequence, class _Env>
     concept __with_member_alias = __mvalid<__member_alias_t, _Sequence, _Env>;
@@ -813,13 +813,13 @@ namespace exec {
         static_assert(
           __well_formed_item_senders<_Sequence>,
           STDEXEC_ERROR_GET_ITEM_TYPES_HAS_INVALID_RETURN_TYPE);
-      } else {
-        stdexec::__diagnose_sender_concept_failure<_Sequence, _Env...>();
+        //} else {
+        //  stdexec::__diagnose_sender_concept_failure<_Sequence, _Env...>();
       }
 #if STDEXEC_MSVC() || STDEXEC_NVHPC()
       // MSVC and NVHPC need more encouragement to print the type of the
       // error.
-      _Completions __what = 0;
+//      _Completions __what = 0;
 #endif
     }
   }