remove the dependence of __variant.hpp on <memory>

Author: ericniebler

include/nvexec/detail/cuda_fwd.cuh

@@ -25,7 +25,7 @@
 #include "config.cuh"
 #include <cuda/std/detail/__config>
 
-#if _LIBCUDACXX_STD_VER > 17 && _LIBCUDACXX_CUDA_API_VERSION < 1009000
+#if _LIBCUDACXX_STD_VER > 17 && _LIBCUDACXX_CUDA_API_VERSION < 1'009'000
 #  define STDEXEC_LIBCUDACXX_NEEDS_ATOMIC_WORAROUND() 1
 #else
 #  define STDEXEC_LIBCUDACXX_NEEDS_ATOMIC_WORAROUND() 0

include/stdexec/__detail/__variant.hpp

@@ -21,7 +21,6 @@
 #include "__scope.hpp"
 
 #include <cstddef>
-#include <memory>
 #include <new>
 #include <utility>
 
@@ -84,7 +83,7 @@ namespace stdexec {
       STDEXEC_ATTRIBUTE(host, device) void __destroy() noexcept {
         auto __index = std::exchange(__index_, __variant_npos);
         if (__variant_npos != __index) {
-          ((_Is == __index ? std::destroy_at(static_cast<_Ts *>(__get_ptr())) : void(0)), ...);
+          ((_Is == __index ? static_cast<_Ts *>(__get_ptr())->~_Ts() : void(0)), ...);
         }
       }