Merge pull request NVIDIA#1449 from NVIDIA/drive-by-simplification

use `__tuple::for_each` to simplify some senders

Author: ericniebler

include/exec/start_now.hpp

@@ -180,8 +180,7 @@ namespace exec {
             __scope.nest(static_cast<stdexec::__cvref_t<_SenderIds>&&>(__sndr)),
             __receiver_t{this})}...} {
         // Start all of the child operations
-        __op_state_.apply(
-          [](auto&... __op_state) noexcept { (stdexec::start(__op_state), ...); }, __op_state_);
+        __op_state_.for_each(stdexec::start, __op_state_);
       }
 
       bool request_stop() noexcept {

include/exec/when_any.hpp

@@ -219,7 +219,7 @@ namespace exec {
           if (this->__stop_source_.stop_requested()) {
             stdexec::set_stopped(static_cast<_Receiver&&>(this->__rcvr_));
           } else {
-            __ops_.apply([](auto&... __ops) { (stdexec::start(__ops), ...); }, __ops_);
+            __ops_.for_each(stdexec::start, __ops_);
           }
         }
 

include/nvexec/stream/when_all.cuh

@@ -378,9 +378,7 @@ namespace nvexec::STDEXEC_STREAM_DETAIL_NS {
             if constexpr (sizeof...(SenderIds) == 0) {
               complete();
             } else {
-              child_states_.apply(
-                [](auto&... __child_ops) noexcept -> void { (stdexec::start(__child_ops), ...); },
-                child_states_);
+              child_states_.for_each(stdexec::start, child_states_);
             }
           }
         }