Remove _CCCL_NO_FOLD_EXPRESSIONS

libcudacxx/include/cuda/std/__cccl/dialect.h

@@ -80,11 +80,6 @@
 #  define _CCCL_NO_CONCEPTS
 #endif // _CCCL_STD_VER <= 2017 || __cpp_concepts < 201907L
 
-// Fold expressions are only available from C++17 onwards
-#if __cpp_fold_expressions < 201603L
-#  define _CCCL_NO_FOLD_EXPRESSIONS
-#endif // __cpp_fold_expressions < 201603L
-
 // Inline variables are only available from C++17 onwards
 #if __cpp_inline_variables < 201606L
 #  define _CCCL_NO_INLINE_VARIABLES

libcudacxx/include/cuda/std/__type_traits/fold.h

@@ -21,13 +21,9 @@
 #endif // no system header
 
 #include <cuda/std/__type_traits/integral_constant.h>
-#include <cuda/std/__type_traits/is_same.h>
-#include <cuda/std/__type_traits/negation.h>
 
 _LIBCUDACXX_BEGIN_NAMESPACE_STD
 
-#if !defined(_CCCL_NO_FOLD_EXPRESSIONS)
-
 // Use fold expressions when possible to implement __fold_and[_v] and
 // __fold_or[_v].
 template <bool... _Preds>
@@ -42,28 +38,6 @@ using __fold_and = bool_constant<bool((_Preds && ...))>; // cast to bool to avoi
 template <bool... _Preds>
 using __fold_or = bool_constant<bool((_Preds || ...))>; // cast to bool to avoid error from gcc < 8
 
-#else // ^^^ !_CCCL_NO_FOLD_EXPRESSIONS / _CCCL_NO_FOLD_EXPRESSIONS vvv
-
-// Otherwise, we can use a helper class to implement __fold_and and __fold_or.
-template <bool... _Preds>
-struct __fold_helper;
-
-template <bool... _Preds>
-using __fold_and = _IsSame<__fold_helper<true, _Preds...>, __fold_helper<_Preds..., true>>;
-
-template <bool... _Preds>
-using __fold_or = _Not<_IsSame<__fold_helper<false, _Preds...>, __fold_helper<_Preds..., false>>>;
-
-#  if !defined(_CCCL_NO_VARIABLE_TEMPLATES)
-template <bool... _Preds>
-inline constexpr bool __fold_and_v = __fold_and<_Preds...>::value;
-
-template <bool... _Preds>
-inline constexpr bool __fold_or_v = __fold_or<_Preds...>::value;
-#  endif // !_CCCL_NO_VARIABLE_TEMPLATES
-
-#endif // _CCCL_NO_FOLD_EXPRESSIONS
-
 _LIBCUDACXX_END_NAMESPACE_STD
 
 #endif // _LIBCUDACXX___TYPE_TRAITS_FOLD_H

libcudacxx/include/cuda/std/__type_traits/type_set.h

@@ -25,6 +25,7 @@
 #include <cuda/std/__type_traits/fold.h>
 #include <cuda/std/__type_traits/integral_constant.h>
 #include <cuda/std/__type_traits/is_base_of.h>
+#include <cuda/std/__type_traits/is_same.h>
 #include <cuda/std/__type_traits/type_identity.h>
 #include <cuda/std/cstddef>