try to fix the CUDA builds

Author: ericniebler

include/stdexec/__detail/__atomic.hpp

@@ -28,6 +28,8 @@
 
 #include <memory>
 
+//#include <stdatomic.h> // IWYU pragma: keep for atomic_* functions
+
 namespace STDEXEC::__std {
 #if STDEXEC_HAS_CUDA_STD_ATOMIC()
 
@@ -44,7 +46,7 @@ namespace STDEXEC::__std {
   using cuda::std::atomic_thread_fence;
   using cuda::std::atomic_signal_fence;
 
-#else
+#else // ^^^ STDEXEC_HAS_CUDA_STD_ATOMIC() / vvv !STDEXEC_HAS_CUDA_STD_ATOMIC()
 
   using std::atomic;
   using std::atomic_flag;
@@ -99,18 +101,20 @@ namespace STDEXEC::__std {
       __atomic_store_n(__ptr_, __desired, __map_memory_order(__order));
     }
   };
-#  endif
+#  endif // ^^^ __cpp_lib_atomic_ref < 2018'06L
+
+#endif // ^^^ !STDEXEC_HAS_CUDA_STD_ATOMIC()
 
   constexpr memory_order __memory_order_load(memory_order __order) noexcept {
     return __order == memory_order_acq_rel ? memory_order_acquire
          : __order == memory_order_release ? memory_order_relaxed
                                            : __order;
   }
 
-#  if __cpp_lib_atomic_shared_ptr >= 2017'11L
+#if __cpp_lib_atomic_shared_ptr >= 2017'11L
   template <class _Ty>
   using __atomic_shared_ptr = std::atomic<std::shared_ptr<_Ty>>;
-#  else
+#elif !STDEXEC_CLANG() || !STDEXEC_CUDA_COMPILATION()
   template <typename _Ty>
   struct __atomic_shared_ptr {
     using value_type = std::shared_ptr<_Ty>;
@@ -148,16 +152,17 @@ namespace STDEXEC::__std {
     }
 
     std::shared_ptr<_Ty> load(memory_order __order = memory_order_seq_cst) const noexcept {
-      return atomic_load_explicit(&__ptr_, __order);
+      return atomic_load_explicit(&__ptr_, static_cast<std::memory_order>(__order));
     }
 
     void store(std::shared_ptr<_Ty> __ptr, memory_order __order = memory_order_seq_cst) noexcept {
-      atomic_store_explicit(&__ptr_, std::move(__ptr), __order);
+      atomic_store_explicit(&__ptr_, std::move(__ptr), static_cast<std::memory_order>(__order));
     }
 
     std::shared_ptr<_Ty>
       exchange(std::shared_ptr<_Ty> __ptr, memory_order __order = memory_order_seq_cst) noexcept {
-      return atomic_exchange_explicit(&__ptr_, std::move(__ptr), __order);
+      return atomic_exchange_explicit(
+        &__ptr_, std::move(__ptr), static_cast<std::memory_order>(__order));
     }
 
     bool compare_exchange_weak(
@@ -166,15 +171,23 @@ namespace STDEXEC::__std {
       memory_order __success,
       memory_order __failure) noexcept {
       return atomic_compare_exchange_weak_explicit(
-        &__ptr_, &__expected, std::move(__desired), __success, __failure);
+        &__ptr_,
+        &__expected,
+        std::move(__desired),
+        static_cast<std::memory_order>(__success),
+        static_cast<std::memory_order>(__failure));
     }
 
     bool compare_exchange_weak(
       std::shared_ptr<_Ty>& __expected,
       std::shared_ptr<_Ty> __desired,
       memory_order __order = memory_order_seq_cst) noexcept {
       return atomic_compare_exchange_weak_explicit(
-        &__ptr_, &__expected, std::move(__desired), __order, __memory_order_load(__order));
+        &__ptr_,
+        &__expected,
+        std::move(__desired),
+        static_cast<std::memory_order>(__order),
+        static_cast<std::memory_order>(__memory_order_load(__order)));
     }
 
     bool compare_exchange_strong(
@@ -183,15 +196,23 @@ namespace STDEXEC::__std {
       memory_order __upon_success,
       memory_order __upon_failure) noexcept {
       return atomic_compare_exchange_strong_explicit(
-        &__ptr_, &__expected, std::move(__desired), __upon_success, __upon_failure);
+        &__ptr_,
+        &__expected,
+        std::move(__desired),
+        static_cast<std::memory_order>(__upon_success),
+        static_cast<std::memory_order>(__upon_failure));
     }
 
     bool compare_exchange_strong(
       std::shared_ptr<_Ty>& __expected,
       std::shared_ptr<_Ty> __desired,
       memory_order __order = memory_order_seq_cst) noexcept {
       return atomic_compare_exchange_strong_explicit(
-        &__ptr_, &__expected, std::move(__desired), __order, __memory_order_load(__order));
+        &__ptr_,
+        &__expected,
+        std::move(__desired),
+        static_cast<std::memory_order>(__order),
+        static_cast<std::memory_order>(__memory_order_load(__order)));
     }
 
    private:
@@ -201,7 +222,6 @@ namespace STDEXEC::__std {
   template <typename _Ty>
   __atomic_shared_ptr(std::shared_ptr<_Ty>) -> __atomic_shared_ptr<_Ty>;
 
-#  endif
+#endif // ^^^ __cpp_lib_atomic_shared_ptr < 2017'11L
 
-#endif
 } // namespace STDEXEC::__std