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extend the concept portability macros to support _Convertible_to(T) and _Derived_from(T) #8768

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extend the concept portability macros to support _Convertible_to(T) and _Derived_from(T) #8768

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d74e764
extend the concept portability macros to support `_Convertible_to(T)`…
ericniebler Apr 30, 2026
804f994
avoid nvcc-12.0 concepts parsing bug
ericniebler Apr 30, 2026
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10 changes: 5 additions & 5 deletions libcudacxx/include/cuda/__algorithm/common.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,9 +38,9 @@ using __as_span_t = ::cuda::std::span<::cuda::std::remove_reference_t<::cuda::st
//! @brief A concept that checks if the type can be converted to a `cuda::std::span`.
//! The type must be a contiguous range.
template <typename _Tp>
_CCCL_CONCEPT __spannable = _CCCL_REQUIRES_EXPR((_Tp))( //
requires(::cuda::std::ranges::contiguous_range<_Tp>), //
requires(::cuda::std::convertible_to<_Tp, __as_span_t<_Tp>>));
_CCCL_CONCEPT __spannable = _CCCL_REQUIRES_EXPR((_Tp), _Tp&& __value)( //
_Satisfies(cuda::std::ranges::contiguous_range)::cuda::std::forward<_Tp>(__value), //
_Convertible_to(__as_span_t<_Tp>)::cuda::std::forward<_Tp>(__value));

template <typename _Tp>
using __as_mdspan_t =
Expand All @@ -52,8 +52,8 @@ using __as_mdspan_t =
//! @brief A concept that checks if the type can be converted to a `cuda::std::mdspan`.
//! The type must have a conversion to `__as_mdspan_t<_Tp>`.
template <typename _Tp>
_CCCL_CONCEPT __mdspannable =
_CCCL_REQUIRES_EXPR((_Tp))(requires(::cuda::std::convertible_to<_Tp, __as_mdspan_t<_Tp>>));
_CCCL_CONCEPT __mdspannable = _CCCL_REQUIRES_EXPR((_Tp), _Tp&& __value)( //
_Convertible_to(__as_mdspan_t<_Tp>)::cuda::std::forward<_Tp>(__value));

template <typename _Tp>
[[nodiscard]] _CCCL_HOST_API constexpr auto __as_mdspan(_Tp&& __value) noexcept -> __as_mdspan_t<_Tp>
Expand Down
66 changes: 55 additions & 11 deletions libcudacxx/include/cuda/std/__concepts/concept_macros.h
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Original file line number Diff line number Diff line change
Expand Up @@ -149,11 +149,13 @@ namespace __cccl_unqualified_cuda_std = ::cuda::std; // NOLINT(misc-unused-alias
// - _Satisfies(CONCEPT...) EXPR...
//
// The last 4 are handled below:
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH_requires _CCCL_PP_CASE(REQUIRES)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH_noexcept _CCCL_PP_CASE(NOEXCEPT)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH_typename _CCCL_PP_CASE(TYPENAME)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH__Same_as _CCCL_PP_CASE(SAME_AS)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH__Satisfies _CCCL_PP_CASE(SATISFIES)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH_requires _CCCL_PP_CASE(REQUIRES)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH_noexcept _CCCL_PP_CASE(NOEXCEPT)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH_typename _CCCL_PP_CASE(TYPENAME)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH__Same_as _CCCL_PP_CASE(SAME_AS)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH__Satisfies _CCCL_PP_CASE(SATISFIES)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH__Convertible_to _CCCL_PP_CASE(CONVERTIBLE_TO)
#define _CCCL_CONCEPT_REQUIREMENT_SWITCH__Derived_from _CCCL_PP_CASE(DERIVED_FROM)

// Converts "requires(ARGS...)" to "ARGS..."
#define _CCCL_CONCEPT_EAT_REQUIRES_(...) _CCCL_PP_CAT(_CCCL_CONCEPT_EAT_REQUIRES_, __VA_ARGS__)
Expand Down Expand Up @@ -184,18 +186,42 @@ namespace __cccl_unqualified_cuda_std = ::cuda::std; // NOLINT(misc-unused-alias
_CCCL_PP_CAT(_CCCL, _CCCL_PP_EVAL(_CCCL_PP_FIRST, _CCCL_PP_CAT(_CCCL_CONCEPT_GET_TYPE_FROM_SAME_AS_, __VA_ARGS__)))
#define _CCCL_CONCEPT_GET_TYPE_FROM_SAME_AS__Same_as(...) _PP_EXPAND(__VA_ARGS__),

// Converts "_Satisfies(TYPE) EXPR..." to "EXPR..."
// Converts "_Satisfies(CONCEPT) EXPR..." to "EXPR..."
#define _CCCL_CONCEPT_EAT_SATISFIES_(...) _CCCL_PP_CAT(_CCCL_CONCEPT_EAT_SATISFIES_, __VA_ARGS__)
#define _CCCL_CONCEPT_EAT_SATISFIES__Satisfies(...)

// Converts "_Satisfies(TYPE) EXPR..." to "TYPE" (The ridiculous concatenation of _CCCL
// with _PP_EXPAND(__VA_ARGS__) is the only way to get MSVC's broken preprocessor to do macro
// expansion here.)
// Converts "_Satisfies(CONCEPT) EXPR..." to "CONCEPT" (The ridiculous concatenation of
// _CCCL with _PP_EXPAND(__VA_ARGS__) is the only way to get MSVC's broken preprocessor to
// do macro expansion here.)
#define _CCCL_CONCEPT_GET_CONCEPT_FROM_SATISFIES_(...) \
_CCCL_PP_CAT(_CCCL, \
_CCCL_PP_EVAL(_CCCL_PP_FIRST, _CCCL_PP_CAT(_CCCL_CONCEPT_GET_CONCEPT_FROM_SATISFIES_, __VA_ARGS__)))
#define _CCCL_CONCEPT_GET_CONCEPT_FROM_SATISFIES__Satisfies(...) _PP_EXPAND(__VA_ARGS__),

// Converts "_Convertible_to(TYPE) EXPR..." to "EXPR..."
#define _CCCL_CONCEPT_EAT_CONVERTIBLE_TO_(...) _CCCL_PP_CAT(_CCCL_CONCEPT_EAT_CONVERTIBLE_TO_, __VA_ARGS__)
#define _CCCL_CONCEPT_EAT_CONVERTIBLE_TO__Convertible_to(...)

// Converts "_Convertible_to(TYPE) EXPR..." to "TYPE" (The ridiculous concatenation of
// _CCCL with _PP_EXPAND(__VA_ARGS__) is the only way to get MSVC's broken preprocessor to
// do macro expansion here.)
#define _CCCL_CONCEPT_GET_TYPE_FROM_CONVERTIBLE_TO_(...) \
_CCCL_PP_CAT(_CCCL, \
_CCCL_PP_EVAL(_CCCL_PP_FIRST, _CCCL_PP_CAT(_CCCL_CONCEPT_GET_TYPE_FROM_CONVERTIBLE_TO_, __VA_ARGS__)))
#define _CCCL_CONCEPT_GET_TYPE_FROM_CONVERTIBLE_TO__Convertible_to(...) _PP_EXPAND(__VA_ARGS__),

// Converts "_Derived_from(TYPE) EXPR..." to "EXPR..."
#define _CCCL_CONCEPT_EAT_DERIVED_FROM_(...) _CCCL_PP_CAT(_CCCL_CONCEPT_EAT_DERIVED_FROM_, __VA_ARGS__)
#define _CCCL_CONCEPT_EAT_DERIVED_FROM__Derived_from(...)

// Converts "_Derived_from(TYPE) EXPR..." to "TYPE" (The ridiculous concatenation of
// _CCCL with _PP_EXPAND(__VA_ARGS__) is the only way to get MSVC's broken preprocessor to
// do macro expansion here.)
#define _CCCL_CONCEPT_GET_TYPE_FROM_DERIVED_FROM_(...) \
_CCCL_PP_CAT(_CCCL, \
_CCCL_PP_EVAL(_CCCL_PP_FIRST, _CCCL_PP_CAT(_CCCL_CONCEPT_GET_TYPE_FROM_DERIVED_FROM_, __VA_ARGS__)))
#define _CCCL_CONCEPT_GET_TYPE_FROM_DERIVED_FROM__Derived_from(...) _PP_EXPAND(__VA_ARGS__),

// Here are the implementations of the internal macros, first for when concepts
// are available, and then for when they're not.
#if _CCCL_HAS_CONCEPTS() || defined(_CCCL_DOXYGEN_INVOKED)
Expand All @@ -222,6 +248,12 @@ namespace __cccl_unqualified_cuda_std = ::cuda::std; // NOLINT(misc-unused-alias
{_CCCL_CONCEPT_EAT_SAME_AS_(_REQ)}->_CCCL_CONCEPT_VSTD::same_as<_CCCL_CONCEPT_GET_TYPE_FROM_SAME_AS_(_REQ)>
# define _CCCL_CONCEPT_REQUIREMENT_CASE_SATISFIES(_REQ) \
{_CCCL_CONCEPT_EAT_SATISFIES_(_REQ)}->_CCCL_CONCEPT_GET_CONCEPT_FROM_SATISFIES_(_REQ)
# define _CCCL_CONCEPT_REQUIREMENT_CASE_CONVERTIBLE_TO(_REQ) \
{_CCCL_CONCEPT_EAT_CONVERTIBLE_TO_(_REQ)} \
->_CCCL_CONCEPT_VSTD::convertible_to<_CCCL_CONCEPT_GET_TYPE_FROM_CONVERTIBLE_TO_(_REQ)>
# define _CCCL_CONCEPT_REQUIREMENT_CASE_DERIVED_FROM(_REQ) \
{_CCCL_CONCEPT_EAT_DERIVED_FROM_(_REQ)} \
->_CCCL_CONCEPT_VSTD::derived_from<_CCCL_CONCEPT_GET_TYPE_FROM_DERIVED_FROM_(_REQ)>

# define _CCCL_FRAGMENT(_NAME, ...) _NAME<__VA_ARGS__>

Expand Down Expand Up @@ -269,10 +301,22 @@ namespace __cccl_unqualified_cuda_std = ::cuda::std; // NOLINT(misc-unused-alias
# define _CCCL_CONCEPT_REQUIREMENT_CASE_SATISFIES(_REQ) \
::__cccl_requires < _CCCL_CONCEPT_GET_CONCEPT_FROM_SATISFIES_(_REQ) < decltype(_CCCL_CONCEPT_EAT_SATISFIES_(_REQ)) \
>>
# define _CCCL_CONCEPT_REQUIREMENT_CASE_CONVERTIBLE_TO(_REQ) \
::__cccl_requires<::cuda::std::convertible_to<_CCCL_CONCEPT_CONVERTIBLE_TO_REQUIREMENT_(_REQ)>>
# define _CCCL_CONCEPT_REQUIREMENT_CASE_DERIVED_FROM(_REQ) \
::__cccl_requires<::cuda::std::derived_from<_CCCL_CONCEPT_DERIVED_FROM_REQUIREMENT_(_REQ)>>

// Converts "_Same_as(TYPE) EXPR..." to "TYPE, decltype(EXPR...)"
// Converts "_Same_as(TYPE) EXPR..." to "decltype(EXPR...), TYPE"
# define _CCCL_CONCEPT_SAME_AS_REQUIREMENT_(_REQ) \
_CCCL_CONCEPT_GET_TYPE_FROM_SAME_AS_(_REQ), decltype(_CCCL_CONCEPT_EAT_SAME_AS_(_REQ))
decltype(_CCCL_CONCEPT_EAT_SAME_AS_(_REQ)), _CCCL_CONCEPT_GET_TYPE_FROM_SAME_AS_(_REQ)
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@Jacobfaib Jacobfaib May 1, 2026

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Why the swap?

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@ericniebler ericniebler May 1, 2026 •
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Just for consistency with the argument order for the _Derived_from and _Convertible_to cases


// Converts "_Convertible_to(TYPE) EXPR..." to "decltype(EXPR...), TYPE"
# define _CCCL_CONCEPT_CONVERTIBLE_TO_REQUIREMENT_(_REQ) \
decltype(_CCCL_CONCEPT_EAT_CONVERTIBLE_TO_(_REQ)), _CCCL_CONCEPT_GET_TYPE_FROM_CONVERTIBLE_TO_(_REQ)

// Converts "_Derived_from(TYPE) EXPR..." to "decltype(EXPR...), TYPE"
# define _CCCL_CONCEPT_DERIVED_FROM_REQUIREMENT_(_REQ) \
decltype(_CCCL_CONCEPT_EAT_DERIVED_FROM_(_REQ)), _CCCL_CONCEPT_GET_TYPE_FROM_DERIVED_FROM_(_REQ)

# if _CCCL_HAS_NOEXCEPT_MANGLING()
// Converts "noexcept(EXPR)" to "::__cccl_requires<noexcept(EXPR)>"
Expand Down
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