Deprecate thrust::null_type

Author: bernhardmgruber

thrust/testing/tuple.cu

@@ -529,6 +529,7 @@ DECLARE_UNITTEST(TestTupleCTAD);
 #endif // _CCCL_STD_VER >= 2017
 
 // Ensure that we are backwards compatible with the old thrust::tuple implementation
+_CCCL_SUPPRESS_DEPRECATED_PUSH
 static_assert(
   thrust::tuple_size<thrust::tuple<thrust::null_type,
                                    thrust::null_type,
@@ -625,3 +626,4 @@ static_assert(
 static_assert(
   thrust::tuple_size<thrust::tuple<int, int, int, int, int, int, int, int, int, thrust::null_type>>::value == 9, "");
 static_assert(thrust::tuple_size<thrust::tuple<int, int, int, int, int, int, int, int, int, int>>::value == 10, "");
+_CCCL_SUPPRESS_DEPRECATED_POP

thrust/thrust/tuple.h

@@ -44,7 +44,7 @@
 THRUST_NAMESPACE_BEGIN
 
 // define null_type for backwards compatibility
-struct null_type
+struct CCCL_DEPRECATED_BECAUSE("Please remove null_type from parameters to tuple<...>") null_type
 {};
 
 _CCCL_HOST_DEVICE inline bool operator==(const null_type&, const null_type&)
@@ -176,6 +176,7 @@ using _CUDA_VSTD::tie;
 THRUST_NAMESPACE_END
 
 _LIBCUDACXX_BEGIN_NAMESPACE_STD
+_CCCL_SUPPRESS_DEPRECATED_PUSH
 
 template <>
 struct tuple_size<tuple<THRUST_NS_QUALIFIER::null_type,
@@ -284,4 +285,5 @@ struct tuple_size<tuple<T0, T1, T2, T3, T4, T5, T6, T7, T8, THRUST_NS_QUALIFIER:
     : tuple_size<tuple<T0, T1, T2, T3, T4, T5, T6, T7, T8>>
 {};
 
+_CCCL_SUPPRESS_DEPRECATED_POP
 _LIBCUDACXX_END_NAMESPACE_STD