Add non-template ref-to-value converting constructor to __basic_any

libcudacxx/include/cuda/__utility/__basic_any/basic_any_value.h

@@ -147,7 +147,7 @@ struct _CCCL_TYPE_VISIBILITY_DEFAULT __basic_any : __basic_any_base<_Interface>
   //! @post `__other.has_value() == false` and `has_value()` is `true` if and
   //! only if `__other.has_value()` was `true`.
   _CCCL_TEMPLATE(class _OtherInterface)
-  _CCCL_REQUIRES((!::cuda::std::same_as<_OtherInterface, _Interface>)
+  _CCCL_REQUIRES((!::cuda::std::same_as<_OtherInterface&, _Interface&>)
                    _CCCL_AND __any_convertible_to<__basic_any<_OtherInterface>, __basic_any>)
   _CCCL_API __basic_any(__basic_any<_OtherInterface>&& __other)
   {
@@ -160,13 +160,33 @@ struct _CCCL_TYPE_VISIBILITY_DEFAULT __basic_any : __basic_any_base<_Interface>
   //! `__icopyable<>`.
   //! @post `has_value() == __other.has_value()`.
   _CCCL_TEMPLATE(class _OtherInterface)
-  _CCCL_REQUIRES((!::cuda::std::same_as<_OtherInterface, _Interface>)
+  _CCCL_REQUIRES((!::cuda::std::same_as<_OtherInterface&, _Interface&>)
                    _CCCL_AND __any_convertible_to<__basic_any<_OtherInterface> const&, __basic_any>)
   _CCCL_API __basic_any(__basic_any<_OtherInterface> const& __other)
   {
     __convert_from(__other);
   }
 
+  //! @brief Non-template converting constructors from the corresponding
+  //! reference type `__basic_any<_Interface&>`. These enable implicit
+  //! conversion from proxy types (e.g. Cython's __Pyx_FakeReference)
+  //! that wrap a `__basic_any<_Interface&>` and provide
+  //! `operator __basic_any<_Interface&>&()`, since non-template parameters
+  //! participate in implicit conversion sequences.
+  //! @pre `_Interface` must extend `__icopyable<>` (converting a ref to
+  //! a value requires copying the referenced object).
+  template <bool _Copyable = __copyable, ::cuda::std::enable_if_t<_Copyable, int> = 0>
+  _CCCL_API __basic_any(__basic_any<_Interface&> const& __other)
+  {
+    __convert_from(__other);
+  }
+
+  template <bool _Copyable = __copyable, ::cuda::std::enable_if_t<_Copyable, int> = 0>
+  _CCCL_API __basic_any(__basic_any<_Interface&>&& __other)
+  {
+    __convert_from(__other);
+  }
+
 #if _CCCL_COMPILER(CLANG, <, 12) || _CCCL_COMPILER(GCC, <, 11)
   // Older versions of clang and gcc need help disambiguating between
   // __basic_any<__ireference<I>> and __basic_any<I&>.

libcudacxx/test/libcudacxx/cuda/memory_resource/any_resource/any_resource.cu

@@ -348,4 +348,83 @@ TEST_CASE("regression test for NVIDIA/cccl#8037", "[container][resource]")
 {
   STATIC_REQUIRE(cuda::std::move_constructible<my_resource_wrapper>);
 }
+
+// Minimal proxy that wraps a value and provides operator T&(), mimicking
+// Cython's __Pyx_FakeReference<T> which wraps intermediate expression results.
+template <typename T>
+struct value_proxy
+{
+  T value;
+
+  template <typename... Args>
+  explicit value_proxy(Args&&... args)
+      : value(std::forward<Args>(args)...)
+  {}
+
+  operator T&()
+  {
+    return value;
+  }
+};
+
+// See https://github.com/NVIDIA/cccl/issues/8316
+TEST_CASE("any_resource from proxy-wrapped resource_ref", "[container][resource]")
+{
+  host_device_resource mr;
+  cuda::mr::resource_ref<cuda::mr::host_accessible> ref{mr};
+
+  SECTION("direct construction from resource_ref")
+  {
+    cuda::mr::any_resource<cuda::mr::host_accessible> any{ref};
+    // Extra parens prevent Catch2's expression decomposition, which triggers
+    // an nvcc bug with auto NTTP deduction in __satisfies during ADL.
+    CHECK((any == ref));
+  }
+
+#  if !_CCCL_CUDA_COMPILER(NVCC, <, 12, 9)
+  // nvcc before CTK 12.9 has a bug where auto NTTP deduction failures in
+  // __satisfies are hard errors instead of SFINAE during overload resolution.
+  SECTION("construction from lvalue proxy-wrapped resource_ref")
+  {
+    value_proxy<cuda::mr::resource_ref<cuda::mr::host_accessible>> proxy{mr};
+    cuda::mr::any_resource<cuda::mr::host_accessible> any{proxy};
+    CHECK((any == ref));
+  }
+
+  SECTION("construction from rvalue proxy-wrapped resource_ref")
+  {
+    cuda::mr::any_resource<cuda::mr::host_accessible> any{
+      value_proxy<cuda::mr::resource_ref<cuda::mr::host_accessible>>{mr}};
+    CHECK((any == ref));
+  }
+#  endif // !_CCCL_CUDA_COMPILER(NVCC, <, 12, 9)
+}
+
+TEST_CASE("any_synchronous_resource from proxy-wrapped synchronous_resource_ref", "[container][resource]")
+{
+  host_device_resource mr;
+  cuda::mr::synchronous_resource_ref<cuda::mr::host_accessible> ref{mr};
+
+  SECTION("direct construction from synchronous_resource_ref")
+  {
+    cuda::mr::any_synchronous_resource<cuda::mr::host_accessible> any{ref};
+    CHECK((any == ref));
+  }
+
+#  if !_CCCL_CUDA_COMPILER(NVCC, <, 12, 9)
+  SECTION("construction from lvalue proxy-wrapped synchronous_resource_ref")
+  {
+    value_proxy<cuda::mr::synchronous_resource_ref<cuda::mr::host_accessible>> proxy{mr};
+    cuda::mr::any_synchronous_resource<cuda::mr::host_accessible> any{proxy};
+    CHECK((any == ref));
+  }
+
+  SECTION("construction from rvalue proxy-wrapped synchronous_resource_ref")
+  {
+    cuda::mr::any_synchronous_resource<cuda::mr::host_accessible> any{
+      value_proxy<cuda::mr::synchronous_resource_ref<cuda::mr::host_accessible>>{mr}};
+    CHECK((any == ref));
+  }
+#  endif // !_CCCL_CUDA_COMPILER(NVCC, <, 12, 9)
+}
 #endif // __CUDA_ARCH__