Merge pull request #1499 from NVIDIA/deprecate-empty-env

deprecate `empty_env`; use `env<>` instead

Author: ericniebler

examples/benchmark/static_thread_pool_old.hpp

@@ -679,7 +679,7 @@ namespace exec_old {
     shared_state shared_state_;
     inner_op_state inner_op_;
 
-    public:
+   public:
     bulk_op_state(
       static_thread_pool& pool,
       Shape shape,

include/exec/async_scope.hpp

@@ -775,7 +775,7 @@ namespace exec {
         return nest_result_t<_Constrained>{&__impl_, static_cast<_Constrained&&>(__c)};
       }
 
-      template <__movable_value _Env = empty_env, sender_in<__spawn_env_t<_Env>> _Sender>
+      template <__movable_value _Env = env<>, sender_in<__spawn_env_t<_Env>> _Sender>
         requires sender_to<nest_result_t<_Sender>, __spawn_receiver_t<_Env>>
       void spawn(_Sender&& __sndr, _Env __env = {}) {
         using __op_t = __spawn_operation_t<nest_result_t<_Sender>, _Env>;
@@ -786,7 +786,7 @@ namespace exec {
           new __op_t{nest(static_cast<_Sender&&>(__sndr)), static_cast<_Env&&>(__env), &__impl_}));
       }
 
-      template <__movable_value _Env = empty_env, sender_in<__env_t<_Env>> _Sender>
+      template <__movable_value _Env = env<>, sender_in<__env_t<_Env>> _Sender>
       auto spawn_future(_Sender&& __sndr, _Env __env = {}) -> __future_t<_Sender, _Env> {
         using __state_t = __future_state<nest_result_t<_Sender>, _Env>;
         auto __state = std::make_unique<__state_t>(

include/exec/finally.hpp

@@ -324,7 +324,7 @@ namespace stdexec {
     static constexpr auto get_completion_signatures = //
       []<class _Sender>(_Sender&&) noexcept           //
       -> __completion_signatures_of_t<                //
-        transform_sender_result_t<default_domain, _Sender, empty_env>> {
+        transform_sender_result_t<default_domain, _Sender, env<>>> {
     };
   };
 } // namespace stdexec

include/exec/repeat_n.hpp

@@ -237,7 +237,7 @@ namespace stdexec {
     static constexpr auto get_completion_signatures = //
       []<class _Sender>(_Sender &&) noexcept          //
       -> __completion_signatures_of_t<                //
-        transform_sender_result_t<default_domain, _Sender, empty_env>> {
+        transform_sender_result_t<default_domain, _Sender, env<>>> {
     };
   };
 } // namespace stdexec

include/exec/sequence/iterate.hpp

@@ -204,7 +204,7 @@ namespace exec {
         return {};
       }
 
-      static auto get_env(__ignore) noexcept -> empty_env {
+      static auto get_env(__ignore) noexcept -> env<> {
         return {};
       }
     };

include/exec/sequence_senders.hpp

@@ -39,7 +39,7 @@ namespace exec {
     concept __all_contained_in = __v<__mall_contained_in<_Needles, _Haystack>>;
 
     // This concept checks if a given sender satisfies the requirements to be returned from `set_next`.
-    template <class _Sender, class _Env = empty_env>
+    template <class _Sender, class _Env = env<>>
     concept next_sender =      //
       sender_in<_Sender, _Env> //
       && __all_contained_in<
@@ -180,7 +180,7 @@ namespace exec {
         }
       }
 
-      template <class _Sender, class _Env = empty_env>
+      template <class _Sender, class _Env = env<>>
       constexpr auto
         operator()(_Sender&&, _Env&& = {}) const noexcept -> decltype(__impl<_Sender, _Env>()()) {
         return {};

include/nvexec/stream/ensure_started.cuh

@@ -348,7 +348,7 @@ namespace nvexec::_strm {
       Sender sndr_;
       __intrusive_ptr<sh_state_> shared_state_;
 
-      template <receiver Receiver, class Env = empty_env>
+      template <receiver Receiver, class Env = env<>>
         requires receiver_of<Receiver, completion_signatures_of_t<__t, Env>>
       auto connect(Receiver rcvr) && noexcept(__nothrow_move_constructible<Receiver>) //
         -> operation_t<Receiver> {

include/stdexec/__detail/__basic_sender.hpp

@@ -93,7 +93,7 @@ namespace stdexec {
       if constexpr (sizeof...(__child) == 1) {
         return __env::__fwd_fn()(stdexec::get_env(__child...));
       } else {
-        return empty_env();
+        return env<>();
       }
     };
 

include/stdexec/__detail/__debug.hpp

@@ -173,10 +173,10 @@ namespace stdexec {
     // understand where in a chain of senders the problem is occurring.
     //
     // ```c++
-    // template <class _Sigs, class _Env = empty_env, class _Sender>
+    // template <class _Sigs, class _Env = env<>, class _Sender>
     //   void __debug_sender(_Sender&& __sndr, _Env = {});
     //
-    // template <class _Env = empty_env, class _Sender>
+    // template <class _Env = env<>, class _Sender>
     //   void __debug_sender(_Sender&& __sndr, _Env = {});
     // ```
     //
@@ -205,7 +205,7 @@ namespace stdexec {
     // At least with clang, this gives me a nice backtrace, at the bottom of
     // which is the faulty `tag_invoke` overload with a mention of the
     // constraint that failed.
-    template <class _Sigs, class _Env = empty_env, class _Sender>
+    template <class _Sigs, class _Env = env<>, class _Sender>
     void __debug_sender(_Sender&& __sndr, const _Env& = {}) {
       if constexpr (!__is_debug_env<_Env>) {
         if (sizeof(_Sender) == ~0u) { // never true
@@ -220,7 +220,7 @@ namespace stdexec {
       }
     }
 
-    template <class _Env = empty_env, class _Sender>
+    template <class _Env = env<>, class _Sender>
     void __debug_sender(_Sender&& __sndr, const _Env& = {}) {
       if constexpr (!__is_debug_env<_Env>) {
         if (sizeof(_Sender) == ~0ul) { // never true

include/stdexec/__detail/__ensure_started.hpp

@@ -36,7 +36,7 @@ namespace stdexec {
     struct __ensure_started_t { };
 
     struct ensure_started_t {
-      template <sender _Sender, class _Env = empty_env>
+      template <sender _Sender, class _Env = env<>>
         requires sender_in<_Sender, _Env> && __decay_copyable<env_of_t<_Sender>>
       [[nodiscard]]
       auto operator()(_Sender&& __sndr, _Env&& __env = {}) const -> __well_formed_sender auto {
@@ -91,7 +91,7 @@ namespace stdexec {
     static constexpr auto get_completion_signatures = //
       []<class _Sender>(_Sender&&) noexcept           //
       -> __completion_signatures_of_t<                //
-        transform_sender_result_t<default_domain, _Sender, empty_env>> {
+        transform_sender_result_t<default_domain, _Sender, env<>>> {
     };
   };
 } // namespace stdexec