disable at_coroutine_exit on apple-clang because it generates bad code

include/exec/at_coroutine_exit.hpp

@@ -25,6 +25,11 @@
 #include <exception>
 #include <tuple>
 
+#if STDEXEC_APPLE_CLANG()
+#  error                                                                                           \
+    "at_coroutine_exit is not supported on Apple Clang due to a compiler bug that causes use-after-scope."
+#endif
+
 namespace experimental::execution
 {
   namespace __at_coro_exit

include/exec/task.hpp

@@ -28,10 +28,13 @@
 #include "../stdexec/functional.hpp"
 
 #include "any_sender_of.hpp"
-#include "at_coroutine_exit.hpp"
 #include "completion_behavior.hpp"
 #include "scope.hpp"
 
+#if !STDEXEC_APPLE_CLANG()
+#  include "at_coroutine_exit.hpp"
+#endif
+
 STDEXEC_PRAGMA_PUSH()
 STDEXEC_PRAGMA_IGNORE_GNU("-Wundefined-inline")
 
@@ -419,6 +422,7 @@ namespace experimental::execution
       __std::coroutine_handle<_Promise> __parent_;
     };
 
+#if !STDEXEC_APPLE_CLANG()
     template <class _Scheduler, class _Promise>
     struct __reschedule_awaiter
     {
@@ -491,6 +495,7 @@ namespace experimental::execution
         return {static_cast<_Scheduler&&>(__sched)};
       }
     };
+#endif
 
     ////////////////////////////////////////////////////////////////////////////////
     // basic_task
@@ -611,13 +616,15 @@ namespace experimental::execution
           }
         }
 
+#  if !STDEXEC_APPLE_CLANG()
         template <class _Scheduler>
           requires __start_scheduler_provider<_Context>
         auto await_transform(__reschedule_coroutine_on_t::__wrapper<_Scheduler> __box) noexcept
           -> decltype(auto)
         {
           return __reschedule_awaiter<_Scheduler, __promise>{__box.__sched_};
         }
+#  endif
 #endif
 
         template <__sender_adaptor_closure_for<__just_void<__scheduler_t>> _Closure>
@@ -718,7 +725,9 @@ namespace experimental::execution
   template <class _Ty>
   using task = basic_task<_Ty, default_task_context<_Ty>>;
 
+#if !STDEXEC_APPLE_CLANG()
   inline constexpr __task::__reschedule_coroutine_on_t reschedule_coroutine_on{};
+#endif
 }  // namespace experimental::execution
 
 namespace exec = experimental::execution;

test/exec/test_at_coroutine_exit.cpp

@@ -17,7 +17,7 @@
 
 #include <stdexec/coroutine.hpp>
 
-#if !STDEXEC_NO_STDCPP_COROUTINES() && !STDEXEC_NO_STDCPP_EXCEPTIONS()
+#if !STDEXEC_NO_STDCPP_COROUTINES() && !STDEXEC_NO_STDCPP_EXCEPTIONS() && !STDEXEC_APPLE_CLANG()
 #  include <catch2/catch_all.hpp>
 #  include <exec/at_coroutine_exit.hpp>
 #  include <exec/on_coro_disposition.hpp>

test/exec/test_task.cpp

@@ -49,6 +49,7 @@ namespace
     return thread_id;
   }
 
+#  if !STDEXEC_APPLE_CLANG()
   auto test_stickiness_for_two_single_thread_contexts_nested(ex::scheduler auto scheduler1,
                                                              ex::scheduler auto,
                                                              auto id1,
@@ -210,6 +211,7 @@ namespace
     auto t   = test_stickiness_for_two_single_thread_contexts(scheduler1, scheduler2, id1, id2);
     ex::sync_wait(std::move(t));
   }
+#  endif
 
   auto test_stick_on_main_nested(ex::scheduler auto sched1,
                                  ex::scheduler auto,