This commit adds a new layout layout_left_padded as standardized in
N5014. It adds a purely internal feature testing macro padded_layouts
and registers layout_left_padded in the std module.
This commit implements LWG4372, because without it's not possible
to properly test padded layouts with a dynamic padding value. It also
implements LWG4314, for consistency with prior layouts.
The implementation uses a _PaddedStorage to deduplicate most of the code
shared between left- and right-padded layouts. It's implemented through
aggregation rather than inheritence, because of a bug related to
inheriting conditionally explicit ctors.
The tests are written such that the canonical version works for
layout_left_padded. A version for layout_right_padded is derived
essentially by reversing the order of the extents.
PR libstdc++/110352
libstdc++-v3/ChangeLog:
* include/bits/version.def (padded_layouts): Add new internal
feature testing macro.
* include/bits/version.h: Regenerate.
* include/std/mdspan (__fwd_prod): New overload.
(layout_left_padded): Add declaration and implementation.
(layout_right_padded): Add declaration only.
(layout_left::mapping::mapping): New overload for left
padded mappings.
(__index_type_cast): New function that performs a checked cast
to index_type.
(__is_left_padded_mapping): New concept.
(__is_right_padded_mapping): Ditto.
(__standardized_mapping): Recognize left and right padded
mappings.
(_LeftPaddedIndices): Traits for left padded details.
(_PaddedStorage): New class for implementing padded layouts.
* src/c++23/std.cc.in (layout_left_padded): Add.
* testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc:
Refactor and add tests for layout_left_padded.
* testsuite/23_containers/mdspan/layouts/ctors.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/empty.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/mapping.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/padded.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/padded_neg.cc: Ditto.
* testsuite/23_containers/mdspan/layouts/padded_traits.h: New
traits.
Signed-off-by: Luc Grosheintz <[email protected]>
---
libstdc++-v3/include/bits/version.def | 10 +
libstdc++-v3/include/bits/version.h | 9 +
libstdc++-v3/include/std/mdspan | 655 ++++++++++++++++-
libstdc++-v3/src/c++23/std.cc.in | 8 +-
.../mdspan/layouts/class_mandate_neg.cc | 1 +
.../23_containers/mdspan/layouts/ctors.cc | 59 +-
.../23_containers/mdspan/layouts/empty.cc | 20 +-
.../23_containers/mdspan/layouts/mapping.cc | 107 ++-
.../23_containers/mdspan/layouts/padded.cc | 673 ++++++++++++++++++
.../mdspan/layouts/padded_neg.cc | 324 +++++++++
.../mdspan/layouts/padded_traits.h | 73 ++
11 files changed, 1922 insertions(+), 17 deletions(-)
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_neg.cc
create mode 100644
libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_traits.h
diff --git a/libstdc++-v3/include/bits/version.def
b/libstdc++-v3/include/bits/version.def
index 3a26234f87e..9fe3ad2feda 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1062,6 +1062,16 @@ ftms = {
cxxmin = 26;
extra_cond = "__glibcxx_assume_aligned "
"&& __glibcxx_is_sufficiently_aligned";
+ };
+};
+
+// Purely internal macro padded layouts.
+ftms = {
+ name = padded_layouts;
+ no_stdname = true; // internal
+ values = {
+ v = 1;
+ cxxmin = 26;
};
};
diff --git a/libstdc++-v3/include/bits/version.h
b/libstdc++-v3/include/bits/version.h
index 46e4c1121e7..d9bf5c8145a 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -1193,6 +1193,15 @@
#endif /* !defined(__cpp_lib_aligned_accessor) &&
defined(__glibcxx_want_aligned_accessor) */
#undef __glibcxx_want_aligned_accessor
+#if !defined(__cpp_lib_padded_layouts)
+# if (__cplusplus > 202302L)
+# define __glibcxx_padded_layouts 1L
+# if defined(__glibcxx_want_all) || defined(__glibcxx_want_padded_layouts)
+# endif
+# endif
+#endif /* !defined(__cpp_lib_padded_layouts) &&
defined(__glibcxx_want_padded_layouts) */
+#undef __glibcxx_want_padded_layouts
+
#if !defined(__cpp_lib_ssize)
# if (__cplusplus >= 202002L)
# define __glibcxx_ssize 201902L
diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index d9b5152b693..6bd75ffde0b 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -71,6 +71,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return true;
}
+ template<typename _IndexType, typename _OIndexType>
+ constexpr _IndexType
+ __index_type_cast(_OIndexType&& __other)
+ {
+ if constexpr (std::is_integral_v<_OIndexType>)
+ {
+ __glibcxx_assert(cmp_less_equal(__other,
+ __gnu_cxx::__int_traits<_IndexType>::__max));
+ if constexpr (std::is_signed_v<_OIndexType>)
+ __glibcxx_assert(__other >= 0);
+ return std::move(__other);
+ }
+ else
+ {
+ auto __ret = static_cast<_IndexType>(std::move(__other));
+ if constexpr (std::is_signed_v<_IndexType>)
+ __glibcxx_assert(__ret >= 0);
+ return __ret;
+ }
+ }
+
template<array _Extents>
class _StaticExtents
{
@@ -261,6 +282,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__static_extents() noexcept
{ return _Extents::_Storage::_S_static_extents(); }
+ template<typename _Extents>
+ constexpr span<const size_t>
+ __static_extents(size_t __begin, size_t __end) noexcept
+ {
+ const auto& __sta_exts = __static_extents<_Extents>();
+ return span<const size_t>(__sta_exts.data() + __begin, __end - __begin);
+ }
+
// Pre-compute: \prod_{i = 0}^r _Extents[i], for r = 0,..., n (exclusive)
template<array _Extents>
constexpr auto __fwd_partial_prods = [] consteval
@@ -476,6 +505,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
// Preconditions: _r < _Extents::rank()
+ template<typename _Extents>
+ constexpr typename _Extents::index_type
+ __fwd_prod(const _Extents& __exts, size_t __begin, size_t __end) noexcept
+ {
+ size_t __sta_prod = [__begin, __end] {
+ span<const size_t> __sta_exts = __static_extents<_Extents>(__begin,
__end);
+ size_t __ret = 1;
+ for(auto __ext : __sta_exts)
+ if (__ext != dynamic_extent)
+ __ret *= __ext;
+ return __ret;
+ }();
+ return __extents_prod(__exts, __sta_prod, __begin, __end);
+ }
+
template<typename _Extents>
constexpr typename _Extents::index_type
__fwd_prod(const _Extents& __exts, size_t __r) noexcept
@@ -567,6 +611,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
class mapping;
};
+#ifdef __glibcxx_padded_layouts
+ template<size_t _PaddingValue>
+ struct layout_left_padded
+ {
+ template<typename _Extents>
+ class mapping;
+ };
+
+ template<size_t _PaddingValue>
+ struct layout_right_padded
+ {
+ template<typename _Extents>
+ class mapping;
+ };
+#endif
+
namespace __mdspan
{
template<typename _Tp>
@@ -669,10 +729,34 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
is_same_v<typename _Layout::template mapping<typename
_Mapping::extents_type>,
_Mapping>;
+ template<template<size_t> typename _Layout, typename _Mapping>
+ concept __padded_mapping_of = __mapping_of<
+ _Layout<_Mapping::padding_value>, _Mapping>;
+
+#ifdef __glibcxx_padded_layouts
+ template<typename _Mapping>
+ constexpr bool __is_left_padded_mapping = __padded_mapping_of<
+ layout_left_padded, _Mapping>;
+
+ template<typename _Mapping>
+ constexpr bool __is_right_padded_mapping = __padded_mapping_of<
+ layout_right_padded, _Mapping>;
+#endif
+
+ template<typename _PaddedMapping>
+ consteval size_t
+ __get_static_stride()
+ { return _PaddedMapping::_PaddedStorage::_S_static_stride; }
+
template<typename _Mapping>
concept __standardized_mapping = __mapping_of<layout_left, _Mapping>
|| __mapping_of<layout_right, _Mapping>
- || __mapping_of<layout_stride, _Mapping>;
+ || __mapping_of<layout_stride, _Mapping>
+#ifdef __glibcxx_padded_layouts
+ || __is_left_padded_mapping<_Mapping>
+ || __is_right_padded_mapping<_Mapping>
+#endif
+ ;
// A tag type to create internal ctors.
class __internal_ctor
@@ -726,6 +810,32 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: mapping(__other.extents(), __mdspan::__internal_ctor{})
{ __glibcxx_assert(*this == __other); }
+#if __glibcxx_padded_layouts
+ template<class _LeftpadMapping>
+ requires __mdspan::__is_left_padded_mapping<_LeftpadMapping>
+ && is_constructible_v<extents_type,
+ typename _LeftpadMapping::extents_type>
+ constexpr
+ explicit(!is_convertible_v<typename _LeftpadMapping::extents_type,
+ extents_type>)
+ mapping(const _LeftpadMapping& __other) noexcept
+ : mapping(__other.extents(), __mdspan::__internal_ctor{})
+ {
+ constexpr size_t __ostride_sta = __mdspan::__get_static_stride<
+ _LeftpadMapping>();
+
+ if constexpr (extents_type::rank() > 1)
+ {
+ if constexpr (extents_type::static_extent(0) != dynamic_extent
+ && __ostride_sta != dynamic_extent)
+ static_assert(extents_type::static_extent(0) == __ostride_sta);
+ else
+ __glibcxx_assert(__other.stride(1)
+ == __other.extents().extent(0));
+ }
+ }
+#endif
+
constexpr mapping&
operator=(const mapping&) noexcept = default;
@@ -1173,6 +1283,547 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
[[no_unique_address]] _Strides _M_strides;
};
+#ifdef __glibcxx_padded_layouts
+ namespace __mdspan
+ {
+ constexpr size_t
+ __least_multiple(size_t __x, size_t __y)
+ {
+ if (__x <= 1)
+ return __y;
+ return (__y / __x + (__y % __x != 0)) * __x ;
+ }
+
+ template<typename _IndexType>
+ constexpr bool
+ __is_representable_least_multiple(size_t __x, size_t __y)
+ {
+ constexpr auto __y_max = __gnu_cxx::__int_traits<_IndexType>::__max;
+ if(std::cmp_greater(__y, __y_max))
+ return false;
+
+ if(__x <= 1)
+ return true;
+
+ auto __max_delta = __y_max - static_cast<_IndexType>(__y);
+ auto __y_mod_x = __y % __x;
+ auto __delta = (__y_mod_x == 0) ? size_t(0) : (__x - __y_mod_x);
+ return std::cmp_less_equal(__delta, __max_delta);
+ }
+
+ template<typename _Extents, size_t _PaddingValue, typename _LayoutTraits,
+ size_t _Rank = _Extents::rank()>
+ concept __valid_static_stride = (_Extents::rank() <= 1)
+ || (_PaddingValue == dynamic_extent)
+ || (_Extents::static_extent(_LayoutTraits::_S_ext_idx) ==
dynamic_extent)
+ || (__is_representable_least_multiple<size_t>(
+ _PaddingValue, _Extents::static_extent(_LayoutTraits::_S_ext_idx)));
+
+ template<size_t _PaddedStride, typename _Extents,
+ typename _LayoutTraits>
+ consteval bool
+ __is_representable_padded_size()
+ {
+ using _IndexType = typename _Extents::index_type;
+ auto __sta_exts = __static_extents<_Extents>(
+ _LayoutTraits::_S_unpad_begin, _LayoutTraits::_S_unpad_end);
+ size_t __max = __gnu_cxx::__int_traits<_IndexType>::__max;
+ return __static_quotient(__sta_exts, __max / _PaddedStride) != 0;
+ }
+
+ template<typename _Extents, size_t _PaddedStride, typename _LayoutTraits,
+ size_t _Rank = _Extents::rank()>
+ concept __valid_padded_size = (_Rank <= 1)
+ || (_PaddedStride == dynamic_extent)
+ || (!__all_static(__static_extents<_Extents>()))
+ || (__contains_zero(__static_extents<_Extents>()))
+ || (__is_representable_padded_size<_PaddedStride, _Extents,
+ _LayoutTraits>());
+
+ template<typename _Extents, typename _Stride, typename... _Indices>
+ constexpr typename _Extents::index_type
+ __linear_index_leftpad(const _Extents& __exts, _Stride __stride,
+ _Indices... __indices)
+ {
+ // i0 + stride*(i1 + extents.extent(1)*...)
+ using _IndexType = typename _Extents::index_type;
+ _IndexType __res = 0;
+ if constexpr (sizeof...(__indices) > 0)
+ {
+ _IndexType __mult = 1;
+
+ auto __update_rest = [&, __pos = 1u](_IndexType __idx) mutable
+ {
+ __res += __idx * __mult;
+ __mult *= __exts.extent(__pos);
+ ++__pos;
+ };
+
+ auto __update = [&](_IndexType __idx, auto... __rest)
+ {
+ __res += __idx;
+ __mult = __stride.extent(0);
+ (__update_rest(__rest), ...);
+ };
+ __update(__indices...);
+ }
+ return __res;
+ }
+
+ template<size_t _Rank>
+ struct _LeftPaddedLayoutTraits
+ {
+ using _LayoutSame = layout_left;
+ using _LayoutOther = layout_right;
+
+ constexpr static const size_t _S_ext_idx = 0;
+ constexpr static const size_t _S_stride_idx = 1;
+ constexpr static const size_t _S_unpad_begin = 1;
+ constexpr static const size_t _S_unpad_end = _Rank;
+
+ template<typename _IndexType, size_t _StaticStride, size_t..._Extents>
+ constexpr static auto _S_make_padded_extent(
+ extents<_IndexType, _StaticStride> __stride,
+ const extents<_IndexType, _Extents...>& __exts)
+ {
+ auto __impl = [&]<size_t... _Is>(integer_sequence<size_t, _Is...>)
+ {
+ return extents<_IndexType, _StaticStride,
+ (_Extents...[_Is + 1])...>{
+ __stride.extent(0), __exts.extent(_Is + 1)...};
+ };
+ return __impl(make_index_sequence<sizeof...(_Extents) - 1>());
+ }
+ };
+
+ template<size_t _PaddingValue, typename _Extents, typename _LayoutTraits>
+ class _PaddedStorage
+ {
+ using _LayoutSame = typename _LayoutTraits::_LayoutSame;
+
+ public:
+ using _IndexType = typename _Extents::index_type;
+ constexpr static size_t _S_rank = _Extents::rank();
+
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 4372. Weaken Mandates: for dynamic padding values in padded layouts
+ static_assert((_PaddingValue == dynamic_extent)
+ || (cmp_less_equal(_PaddingValue,
+ __gnu_cxx::__int_traits<_IndexType>::__max)),
+ "padding_value must be representable as index_type");
+
+ static_assert(__representable_size<_Extents, _IndexType>,
+ "The size of extents_type must be representable as index_type");
+
+ static_assert(__valid_static_stride<_Extents, _PaddingValue,
+ _LayoutTraits>,
+ "The padded stride must be representable as size_t");
+
+ static constexpr size_t _S_static_stride = [] consteval
+ {
+ constexpr size_t __rank = _Extents::rank();
+ if constexpr (__rank <= 1)
+ return 0;
+ else
+ {
+ constexpr size_t __ext_idx = _LayoutTraits::_S_ext_idx;
+ constexpr size_t __sta_ext = _Extents::static_extent(__ext_idx);
+ if constexpr (__sta_ext == 0)
+ return size_t(0);
+ else if constexpr (_PaddingValue == dynamic_extent
+ || __sta_ext == dynamic_extent)
+ return dynamic_extent;
+ else
+ return __least_multiple(_PaddingValue, __sta_ext);
+ }
+ }();
+
+ static_assert(_S_static_stride == dynamic_extent
+ || cmp_less_equal(_S_static_stride,
+ __gnu_cxx::__int_traits<_IndexType>::__max),
+ "Padded stride must be representable as index_type");
+
+ static_assert(__valid_padded_size<_Extents, _S_static_stride,
+ _LayoutTraits>);
+
+ constexpr
+ _PaddedStorage() noexcept
+ {
+ if constexpr (_S_rank > 0)
+ if constexpr (_S_static_stride == dynamic_extent
+ && _S_static_padextent() != dynamic_extent)
+ _M_stride = _Stride{_S_static_padextent()};
+ }
+
+ constexpr explicit
+ _PaddedStorage(const _Extents& __exts)
+ : _M_extents(__exts)
+ {
+ if constexpr (!__all_static(__static_extents<_Extents>()))
+ __glibcxx_assert(__is_representable_extents(_M_extents));
+
+ if constexpr (_S_rank > 1)
+ {
+ _IndexType __stride;
+ if constexpr (_PaddingValue == dynamic_extent)
+ __stride = _M_padextent();
+ else if constexpr (_S_static_padextent() != dynamic_extent)
+ return;
+ else
+ {
+ __stride = static_cast<_IndexType>(
+ __least_multiple(_PaddingValue, _M_padextent()));
+
+ __glibcxx_assert(
+ __is_representable_least_multiple<_IndexType>(
+ _PaddingValue, _M_padextent()));
+ __glibcxx_assert(__is_representable_extents(
+ _LayoutTraits::_S_make_padded_extent(
+ std::dextents<_IndexType, 1>{__stride},
+ _M_extents)));
+ }
+ _M_stride = _Stride{__stride};
+ }
+ }
+
+ constexpr explicit
+ _PaddedStorage(const _Extents& __exts, _IndexType __pad)
+ : _M_extents(__exts)
+ {
+ if constexpr (_PaddingValue != dynamic_extent)
+ __glibcxx_assert(cmp_equal(_PaddingValue, __pad));
+ if constexpr (_S_rank > 1 && _S_static_stride == dynamic_extent)
+ {
+ __glibcxx_assert(
+ __is_representable_least_multiple<_IndexType>(
+ __pad, _M_padextent()));
+
+ _M_stride = _Stride{static_cast<_IndexType>(
+ __least_multiple(__pad, _M_padextent()))};
+
+ __glibcxx_assert(__is_representable_extents(
+ _LayoutTraits::_S_make_padded_extent(
+ _M_stride, _M_extents)));
+ }
+ }
+
+ template<typename _OExtents>
+ constexpr explicit
+ _PaddedStorage(const typename _LayoutSame::mapping<_OExtents>&
+ __other)
+ : _PaddedStorage(_Extents(__other.extents()))
+ {
+ constexpr size_t __stride_idx = _LayoutTraits::_S_stride_idx;
+ constexpr size_t __ext_idx = _LayoutTraits::_S_ext_idx;
+ if constexpr (_S_rank > 1 && _PaddingValue != dynamic_extent)
+ {
+ static_assert(_S_static_stride == dynamic_extent
+ || _OExtents::static_extent(__ext_idx) == dynamic_extent
+ || _S_static_stride == _OExtents::static_extent(__ext_idx),
+ "The padded stride must be compatible with other");
+
+ if constexpr (_S_static_stride == dynamic_extent
+ || _OExtents::static_extent(__stride_idx) == dynamic_extent)
+ __glibcxx_assert(std::cmp_equal(_M_padstride(),
+ _M_padextent()));
+ }
+ }
+
+ template<typename _OExtents>
+ constexpr explicit
+ _PaddedStorage(const typename layout_stride::mapping<_OExtents>&
+ __other)
+ : _M_extents(__other.extents())
+ {
+ __glibcxx_assert(cmp_less_equal(__other.required_span_size(),
+ __gnu_cxx::__int_traits<_IndexType>
+ ::__max));
+
+ constexpr size_t __stride_idx = _LayoutTraits::_S_stride_idx;
+ if constexpr (_S_rank > 1)
+ {
+ if constexpr (_S_static_stride != dynamic_extent)
+ __glibcxx_assert(cmp_equal(__other.stride(__stride_idx),
+ _S_static_stride));
+ else if constexpr (_PaddingValue != dynamic_extent)
+ __glibcxx_assert(cmp_equal(__other.stride(__stride_idx),
+ __least_multiple(_PaddingValue,
+ _M_padextent())));
+ if constexpr (_S_static_stride == dynamic_extent)
+ _M_stride = _Stride{__other.stride(__stride_idx)};
+ }
+ }
+
+ template<typename _SamePaddedMapping>
+ constexpr explicit
+ _PaddedStorage(_LayoutTraits::_LayoutSame,
+ const _SamePaddedMapping& __other)
+ : _M_extents(__other.extents())
+ {
+ if constexpr (_S_rank > 1)
+ {
+ static_assert(_PaddingValue == dynamic_extent
+ || _SamePaddedMapping::padding_value == dynamic_extent
+ || _PaddingValue == _SamePaddedMapping::padding_value,
+ "If neither PaddingValue is dynamic_extent, then they must "
+ "be equal");
+
+ constexpr size_t __ext_idx = _LayoutTraits::_S_ext_idx;
+ constexpr size_t __stride_idx = _LayoutTraits::_S_stride_idx;
+ if constexpr (_S_static_stride != dynamic_extent)
+ __glibcxx_assert(cmp_equal(_S_static_stride,
+ __other.stride(__stride_idx)));
+ else if constexpr (_PaddingValue != dynamic_extent)
+ __glibcxx_assert(cmp_equal(__other.stride(__stride_idx),
+ __least_multiple(
+ _PaddingValue, __other.extents().extent(__ext_idx)))
+ && "The padded stride must be compatible with other");
+
+ if constexpr (_S_static_stride == dynamic_extent)
+ _M_stride = _Stride{__other.stride(__stride_idx)};
+ }
+ __glibcxx_assert(cmp_less_equal(__other.required_span_size(),
+ __gnu_cxx::__int_traits<_IndexType>::__max));
+ }
+
+ template<typename _OtherPaddedMapping>
+ constexpr explicit
+ _PaddedStorage(_LayoutTraits::_LayoutOther,
+ const _OtherPaddedMapping& __other) noexcept
+ : _M_extents(__other.extents())
+ {
+ __glibcxx_assert(cmp_less_equal(__other.required_span_size(),
+ __gnu_cxx::__int_traits<_IndexType>::__max));
+ }
+
+ static constexpr bool
+ _M_is_always_exhaustive() noexcept
+ {
+ if constexpr (_S_rank <= 1)
+ return true;
+ else
+ return _S_static_padextent() != dynamic_extent
+ && _S_static_stride != dynamic_extent
+ && _S_static_padextent() == _S_static_stride;
+ }
+
+ constexpr bool
+ _M_is_exhaustive() const noexcept
+ {
+ if constexpr (_M_is_always_exhaustive())
+ return true;
+ else
+ return cmp_equal(_M_padextent(), _M_padstride());
+ }
+
+ constexpr static size_t
+ _S_static_padextent() noexcept
+ { return _Extents::static_extent(_LayoutTraits::_S_ext_idx); }
+
+ constexpr _IndexType
+ _M_padextent() const noexcept
+ { return _M_extents.extent(_LayoutTraits::_S_ext_idx); }
+
+ constexpr size_t
+ _M_padstride() const noexcept
+ { return _M_stride.extent(0); }
+
+ constexpr _IndexType
+ _M_required_span_size() const noexcept
+ {
+ if constexpr (_S_rank == 0)
+ return 1;
+ else if (__mdspan::__empty(_M_extents))
+ return 0;
+ else
+ {
+ size_t __stride = static_cast<size_t>(_M_padstride());
+ size_t __prod_rest = __mdspan::__fwd_prod(_M_extents,
+ _LayoutTraits::_S_unpad_begin, _LayoutTraits::_S_unpad_end);
+ size_t __delta = _M_padstride() - _M_padextent();
+ return static_cast<_IndexType>(__stride * __prod_rest - __delta);
+ }
+ }
+
+ template<typename _SamePaddedMapping>
+ constexpr bool
+ _M_equal(const _SamePaddedMapping& __other) const noexcept
+ {
+ return _M_extents == __other.extents()
+ && (_S_rank < 2
+ || cmp_equal(_M_stride.extent(0),
+ __other.stride(_LayoutTraits::_S_stride_idx)));
+ }
+
+ using _Stride = std::extents<_IndexType, _S_static_stride>;
+ [[no_unique_address]] _Stride _M_stride;
+ [[no_unique_address]] _Extents _M_extents;
+ };
+ }
+
+ template<size_t _PaddingValue>
+ template<typename _Extents>
+ class layout_left_padded<_PaddingValue>::mapping
+ {
+ public:
+ static constexpr size_t padding_value = _PaddingValue;
+
+ using extents_type = _Extents;
+ using index_type = typename extents_type::index_type;
+ using size_type = typename extents_type::size_type;
+ using rank_type = typename extents_type::rank_type;
+ using layout_type = layout_left_padded<padding_value>;
+
+ private:
+ static constexpr size_t _S_rank = extents_type::rank();
+ using _PaddedStorage = __mdspan::_PaddedStorage<_PaddingValue,
+ _Extents, __mdspan::_LeftPaddedLayoutTraits<_S_rank>>;
+ [[no_unique_address]] _PaddedStorage _M_storage;
+
+ consteval friend size_t
+ __mdspan::__get_static_stride<mapping>();
+
+ constexpr index_type
+ _M_extent(size_t __r) const noexcept
+ { return _M_storage._M_extents.extent(__r); }
+
+ constexpr index_type
+ _M_padstride() const noexcept
+ { return _M_storage._M_stride.extent(0); }
+
+ public:
+ constexpr
+ mapping() noexcept
+ { }
+
+ constexpr
+ mapping(const mapping&) noexcept = default;
+
+ constexpr
+ mapping(const extents_type& __exts)
+ : _M_storage(__exts)
+ { }
+
+ template<__mdspan::__valid_index_type<index_type> _OIndexType>
+ constexpr mapping(const extents_type& __exts, _OIndexType __pad)
+ : _M_storage(__exts,
+ __mdspan::__index_type_cast<index_type>(std::move(__pad)))
+ { }
+
+ template<typename _OExtents>
+ requires is_constructible_v<extents_type, _OExtents>
+ constexpr explicit(!is_convertible_v<_OExtents, extents_type>)
+ mapping(const layout_left::mapping<_OExtents>& __other)
+ : _M_storage(__other)
+ { }
+
+ template<typename _OExtents>
+ requires is_constructible_v<_OExtents, extents_type>
+ constexpr explicit(_OExtents::rank() > 0)
+ mapping(const typename layout_stride::mapping<_OExtents>& __other)
+ : _M_storage(__other)
+ { __glibcxx_assert(*this == __other); }
+
+ template<typename _LeftpadMapping>
+ requires __mdspan::__is_left_padded_mapping<_LeftpadMapping>
+ && is_constructible_v<extents_type,
+ typename _LeftpadMapping::extents_type>
+ constexpr explicit(_S_rank > 1 && (padding_value != dynamic_extent
+ || _LeftpadMapping::padding_value == dynamic_extent))
+ mapping(const _LeftpadMapping& __other)
+ : _M_storage(layout_left{}, __other)
+ { }
+
+ template<typename _RightPaddedMapping>
+ requires (__mdspan::__is_right_padded_mapping<_RightPaddedMapping>
+ || __mdspan::__mapping_of<layout_right, _RightPaddedMapping>)
+ && (_S_rank <= 1)
+ && is_constructible_v<extents_type,
+ typename _RightPaddedMapping::extents_type>
+ constexpr explicit(!is_convertible_v<
+ typename _RightPaddedMapping::extents_type, extents_type>)
+ mapping(const _RightPaddedMapping& __other) noexcept
+ : _M_storage(layout_right{}, __other)
+ { }
+
+ constexpr mapping&
+ operator=(const mapping&) noexcept = default;
+
+ constexpr const extents_type&
+ extents() const noexcept { return _M_storage._M_extents; }
+
+ constexpr array<index_type, _S_rank>
+ strides() const noexcept
+ {
+ array<index_type, _S_rank> __ret;
+ if constexpr (_S_rank > 0)
+ __ret[0] = 1;
+ if constexpr (_S_rank > 1)
+ __ret[1] = _M_padstride();
+ if constexpr (_S_rank > 2)
+ for(size_t __i = 2; __i < _S_rank; ++__i)
+ __ret[__i] = __ret[__i - 1] * _M_extent(__i - 1);
+ return __ret;
+ }
+
+ constexpr index_type
+ required_span_size() const noexcept
+ { return _M_storage._M_required_span_size(); }
+
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 4314. Missing move in mdspan layout mapping::operator()
+ template<__mdspan::__valid_index_type<index_type>... _Indices>
+ requires (sizeof...(_Indices) == _S_rank)
+ constexpr index_type
+ operator()(_Indices... __indices) const noexcept
+ {
+ return __mdspan::__linear_index_leftpad(
+ extents(), _M_storage._M_stride,
+ static_cast<index_type>(std::move(__indices))...);
+ }
+
+ static constexpr bool
+ is_always_exhaustive() noexcept
+ { return _PaddedStorage::_M_is_always_exhaustive(); }
+
+ constexpr bool
+ is_exhaustive() noexcept
+ { return _M_storage._M_is_exhaustive(); }
+
+ static constexpr bool
+ is_always_unique() noexcept { return true; }
+
+ static constexpr bool
+ is_always_strided() noexcept { return true; }
+
+ static constexpr bool
+ is_unique() noexcept { return true; }
+
+ static constexpr bool
+ is_strided() noexcept { return true; }
+
+ constexpr index_type
+ stride(rank_type __r) const noexcept
+ {
+ __glibcxx_assert(__r < _S_rank);
+ if (__r == 0)
+ return 1;
+ else
+ return static_cast<index_type>(
+ static_cast<size_t>(_M_padstride()) *
+ static_cast<size_t>(__mdspan::__fwd_prod(extents(), 1, __r)));
+ }
+
+ template<typename _LeftpadMapping>
+ requires(__mdspan::__is_left_padded_mapping<_LeftpadMapping>
+ && _LeftpadMapping::extents_type::rank() == _S_rank)
+ friend constexpr bool
+ operator==(const mapping& __self, const _LeftpadMapping& __other)
+ noexcept
+ { return __self._M_storage._M_equal(__other); }
+ };
+#endif
+
template<typename _ElementType>
struct default_accessor
{
@@ -1370,7 +2021,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
mdspan(data_handle_type __handle, const mapping_type& __mapping,
const accessor_type& __accessor)
: _M_accessor(__accessor), _M_mapping(__mapping),
- _M_handle(std::move(__handle))
+ _M_handle(std::move(__handle))
{ }
template<typename _OElementType, typename _OExtents, typename _OLayout,
diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/std.cc.in
index 9352482cbdb..f10bab59e2c 100644
--- a/libstdc++-v3/src/c++23/std.cc.in
+++ b/libstdc++-v3/src/c++23/std.cc.in
@@ -1869,9 +1869,11 @@ export namespace std
using std::aligned_accessor;
#endif
using std::mdspan;
- // FIXME layout_left_padded, layout_right_padded, strided_slice,
- // submdspan_mapping_result, full_extent_t, full_extent, submdspan_extents,
- // mdsubspan
+#if __glibcxx_padded_layouts
+ using std::layout_left_padded;
+#endif
+ // FIXME layout_right_padded, strided_slice, submdspan_mapping_result,
+ // full_extent_t, full_extent, submdspan_extents, mdsubspan
}
#endif
diff --git
a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
index 7091153daba..edf07c983da 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
@@ -46,3 +46,4 @@ auto b6 = B<6, std::layout_stride, std::layout_left>(); //
{ dg-error "require
auto b7 = B<7, std::layout_stride, std::layout_stride>(); // { dg-error
"required from" }
// { dg-prune-output "must be representable as index_type" }
+// { dg-prune-output "static assertion failed" }
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
index 23c0a55dae1..8cba8094abc 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
@@ -1,6 +1,7 @@
// { dg-do run { target c++23 } }
#include <mdspan>
+#include "padded_traits.h"
#include <cstdint>
#include <testsuite_hooks.h>
@@ -27,7 +28,6 @@ template<typename Mapping, typename OMapping>
VERIFY(std::cmp_equal(m.stride(i), other.stride(i)));
}
-
template<typename To, typename From>
constexpr void
verify_convertible(From from)
@@ -40,7 +40,10 @@ template<typename To, typename From>
constexpr void
verify_nothrow_convertible(From from)
{
- static_assert(std::is_nothrow_constructible_v<To, From>);
+ if constexpr (is_padded_layout<typename To::layout_type>)
+ static_assert(std::is_constructible_v<To, From>);
+ else
+ static_assert(std::is_nothrow_constructible_v<To, From>);
verify_convertible<To>(from);
}
@@ -57,7 +60,10 @@ template<typename To, typename From>
constexpr void
verify_nothrow_constructible(From from)
{
- static_assert(std::is_nothrow_constructible_v<To, From>);
+ if constexpr (is_padded_layout<typename To::layout_type>)
+ static_assert(std::is_constructible_v<To, From>);
+ else
+ static_assert(std::is_nothrow_constructible_v<To, From>);
verify_constructible<To>(from);
}
@@ -196,6 +202,16 @@ namespace from_extents
// ctor: mapping(mapping<OExtents>)
namespace from_same_layout
{
+ template<typename Layout, typename Extents, typename OExtents>
+ constexpr void
+ verify_convertible(OExtents exts)
+ {
+ using Mapping = typename Layout::mapping<Extents>;
+ using OMapping = typename Layout::mapping<OExtents>;
+
+ ::verify_convertible<Mapping>(OMapping(exts));
+ }
+
template<typename Layout, typename Extents, typename OExtents>
constexpr void
verify_nothrow_convertible(OExtents exts)
@@ -223,8 +239,12 @@ namespace from_same_layout
verify_nothrow_convertible<Layout, std::extents<unsigned int>>(
std::extents<int>{});
- verify_nothrow_constructible<Layout, std::extents<int>>(
- std::extents<unsigned int>{});
+ if constexpr (!is_padded_layout<Layout>)
+ verify_nothrow_constructible<Layout, std::extents<int>>(
+ std::extents<unsigned int>{});
+ else
+ verify_convertible<Layout, std::extents<int>>(
+ std::extents<unsigned int>{});
assert_not_constructible<
typename Layout::mapping<std::extents<int>>,
@@ -234,8 +254,12 @@ namespace from_same_layout
typename Layout::mapping<std::extents<int, 1>>,
typename Layout::mapping<std::extents<int>>>();
- verify_nothrow_constructible<Layout, std::extents<int, 1>>(
- std::extents<int, dyn>{1});
+ if constexpr (!is_padded_layout<Layout>)
+ verify_nothrow_constructible<Layout, std::extents<int, 1>>(
+ std::extents<int, dyn>{1});
+ else
+ verify_convertible<Layout, std::extents<int, 1>>(
+ std::extents<int, dyn>{1});
verify_nothrow_convertible<Layout, std::extents<int, dyn>>(
std::extents<int, 1>{});
@@ -247,8 +271,12 @@ namespace from_same_layout
verify_nothrow_constructible<Layout, std::extents<int, 1, 2>>(
std::extents<int, dyn, 2>{1});
- verify_nothrow_convertible<Layout, std::extents<int, dyn, 2>>(
- std::extents<int, 1, 2>{});
+ if constexpr (!is_padded_layout<Layout>)
+ verify_nothrow_convertible<Layout, std::extents<int, dyn, 2>>(
+ std::extents<int, 1, 2>{});
+ else
+ verify_nothrow_constructible<Layout, std::extents<int, dyn, 2>>(
+ std::extents<int, 1, 2>{});
return true;
}
@@ -424,11 +452,24 @@ template<typename Layout>
from_stride::test_all<Layout>();
}
+template<template<size_t> typename Layout>
+ constexpr void
+ test_padded_all()
+ {
+ test_all<Layout<0>>();
+ test_all<Layout<1>>();
+ test_all<Layout<2>>();
+ test_all<Layout<dyn>>();
+ }
+
int
main()
{
test_all<std::layout_left>();
test_all<std::layout_right>();
+#if __cplusplus > 202302L
+ test_padded_all<std::layout_left_padded>();
+#endif
from_left_or_right::test_all<std::layout_left, std::layout_right>();
from_left_or_right::test_all<std::layout_right, std::layout_left>();
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
index cbc425f6c15..05188432f14 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
@@ -35,7 +35,8 @@ template<typename Layout, typename Int>
{
constexpr Int n1 = std::numeric_limits<Int>::max();
constexpr size_t n2 = std::dynamic_extent - 1;
- constexpr size_t n = std::cmp_less(n1, n2) ? size_t(n1) : n2;
+ // Allow some room for padding.
+ constexpr size_t n = (std::cmp_less(n1, n2) ? size_t(n1) : n2) - 4;
verify_all(typename Layout::mapping<std::extents<Int, n, n, 0, n, n>>{});
verify_all(typename Layout::mapping<std::extents<Int, 0, n, n, n>>{});
@@ -73,7 +74,8 @@ template<typename Layout, typename Int>
{
constexpr Int n1 = std::numeric_limits<Int>::max();
constexpr size_t n2 = std::dynamic_extent - 1;
- constexpr Int n = std::cmp_less(n1, n2) ? n1 : Int(n2);
+ // Allow some room for padding.
+ constexpr Int n = (std::cmp_less(n1, n2) ? n1 : Int(n2)) - 4;
verify_all(make_mapping<Layout>(
std::extents<Int, dyn, dyn, 0, dyn, dyn>{n, n, n, n}));
@@ -121,11 +123,25 @@ template<typename Layout>
return true;
}
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_padded_all()
+ {
+ static_assert(test_all<Layout<0>>());
+ static_assert(test_all<Layout<1>>());
+ static_assert(test_all<Layout<2>>());
+ static_assert(test_all<Layout<dyn>>());
+ return true;
+ }
+
int
main()
{
static_assert(test_all<std::layout_left>());
static_assert(test_all<std::layout_right>());
static_assert(test_all<std::layout_stride>());
+#if __cplusplus > 202302L
+ static_assert(test_padded_all<std::layout_left_padded>());
+#endif
return 0;
}
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
index db15e2a48f3..10ce622523d 100644
--- a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
@@ -2,6 +2,7 @@
#include <mdspan>
#include "../int_like.h"
+#include "padded_traits.h"
#include <cstdint>
#include <testsuite_hooks.h>
@@ -370,6 +371,37 @@ template<>
}
};
+#if __cplusplus > 202302L
+template<typename Layout>
+ requires is_left_padded<Layout>
+ struct TestStride2D<Layout>
+ {
+ static constexpr void
+ run()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_typename<Layout>()>;
+ using Extents = typename Traits::extents_type<std::extents<int, 3, 5>>;
+ using Mapping = typename Layout::mapping<Extents>;
+ constexpr size_t padding_value = Mapping::padding_value;
+
+ Mapping m;
+ size_t effective_pad = (padding_value == 0 || padding_value == dyn)
+ ? size_t(1) : padding_value;
+
+ constexpr auto i0 = is_left_padded<Layout> ? 0 : 1;
+ VERIFY(m.stride(i0) == 1);
+
+ // The next multiple of padding_value, that's greater or equal
+ // to exts.extent(0) is the unique value in the range:
+ // [exts.extent(0), exts.extent(0) + padding_value)
+ // that is divisible by padding_value.
+ auto stride = Traits::padded_stride(m);
+ VERIFY((stride % effective_pad) == 0);
+ VERIFY(3 <= stride && std::cmp_less(stride, 3 + effective_pad));
+ }
+ };
+#endif
+
template<typename Layout>
constexpr void
test_stride_2d()
@@ -423,6 +455,40 @@ template<>
}
};
+#if __cplusplus > 202302L
+template<typename Layout>
+ requires is_left_padded<Layout>
+ struct TestStride3D<Layout>
+ {
+ static constexpr void
+ run()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_typename<Layout>()>;
+ using Extents = typename Traits::extents_type<std::extents<int, 3, 5,
7>>;
+ using Mapping = typename Layout::mapping<Extents>;
+ constexpr size_t padding_value = Mapping::padding_value;
+
+ Mapping m;
+ size_t effective_pad = (padding_value == 0 || padding_value == dyn)
+ ? size_t(1) : padding_value;
+
+ constexpr auto i0 = is_left_padded<Layout> ? 0 : 2;
+ VERIFY(m.stride(i0) == 1);
+
+ // The next multiple of padding_value, that's greater or equal
+ // to exts.extent(0) is the unique value in the range:
+ // [exts.extent(0), exts.extent(0) + padding_value)
+ // that is divisible by padding_value.
+ auto stride = Traits::padded_stride(m);
+ VERIFY((stride % effective_pad) == 0);
+ VERIFY(3 <= stride && std::cmp_less(stride, 3 + effective_pad));
+
+ constexpr auto i2 = is_left_padded<Layout> ? 2 : 0;
+ VERIFY(stride * 5 == m.stride(i2));
+ }
+ };
+#endif
+
template<typename Layout>
constexpr void
test_stride_3d()
@@ -451,7 +517,8 @@ template<typename Layout>
test_has_stride_0d()
{
using Mapping = typename Layout::mapping<std::extents<int>>;
- constexpr bool expected = std::is_same_v<Layout, std::layout_stride>;
+ constexpr bool expected = !(std::is_same_v<Layout, std::layout_left>
+ || std::is_same_v<Layout, std::layout_right>);
static_assert(has_stride<Mapping> == expected);
}
@@ -595,16 +662,54 @@ template<typename Layout>
test_has_op_eq<Layout, Layout, true>();
}
+#if __cplusplus > 202302L
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_padded_all()
+ {
+ test_all<Layout<0>>();
+ test_all<Layout<1>>();
+ test_all<Layout<2>>();
+ test_all<Layout<5>>();
+ test_all<Layout<dyn>>();
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_padded_has_op_eq()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ test_has_op_eq<typename Traits::layout_same, Layout<0>, false>();
+ test_has_op_eq<typename Traits::layout_same, Layout<6>, false>();
+ test_has_op_eq<typename Traits::layout_same, Layout<dyn>, false>();
+ // The next one looks strange, because it's neither. Somehow, the
+ // conversion rules seem to be playing a critical role again.
+ // test_has_op_eq<typename Traits::layout_other, Layout<0>, false>();
+
+ test_has_op_eq<Layout<2>, Layout<6>, true>();
+ test_has_op_eq<Layout<2>, Layout<dyn>, true>();
+ return true;
+ }
+#endif
+
int
main()
{
test_all<std::layout_left>();
test_all<std::layout_right>();
test_all<std::layout_stride>();
+#if __cplusplus > 202302L
+ test_padded_all<std::layout_left_padded>();
+#endif
test_has_op_eq<std::layout_right, std::layout_left, false>();
test_has_op_eq<std::layout_right, std::layout_stride, true>();
test_has_op_eq<std::layout_left, std::layout_stride, true>();
+#if __cplusplus > 202302L
+ test_padded_has_op_eq<std::layout_left_padded>();
+#endif
+
test_has_op_eq_peculiar();
return 0;
}
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded.cc
new file mode 100644
index 00000000000..d43b84ef875
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded.cc
@@ -0,0 +1,673 @@
+// { dg-do run { target c++26 } }
+#include <mdspan>
+
+#include <cstdint>
+#include "../int_like.h"
+#include "padded_traits.h"
+#include <testsuite_hooks.h>
+
+constexpr size_t dyn = std::dynamic_extent;
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_representable_padded_size()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ {
+ using E = typename Traits::extents_type<std::extents<uint8_t, 64, 2>>;
+ [[maybe_unused]] typename Layout<1>::mapping<E> m1;
+ }
+
+ {
+ using E = typename Traits::extents_type<std::extents<uint8_t, 0, 2>>;
+ [[maybe_unused]] typename Layout<0>::mapping<E> m1;
+ [[maybe_unused]] typename Layout<1>::mapping<E> m2;
+ [[maybe_unused]] typename Layout<128>::mapping<E> m3;
+ [[maybe_unused]] typename Layout<255>::mapping<E> m4;
+ }
+
+ {
+ using E = typename Traits::extents_type<std::extents<uint8_t, 0, 2>>;
+ [[maybe_unused]] typename Layout<dyn>::mapping<E> m1(E{}, 0);
+ [[maybe_unused]] typename Layout<dyn>::mapping<E> m2(E{}, 1);
+ [[maybe_unused]] typename Layout<dyn>::mapping<E> m3(E{}, 128);
+ [[maybe_unused]] typename Layout<dyn>::mapping<E> m4(E{}, 255);
+ }
+
+ {
+ using E = typename Traits::extents_type<std::extents<uint8_t, dyn, 2>>;
+ [[maybe_unused]] typename Layout<0>::mapping<E> m1;
+ [[maybe_unused]] typename Layout<1>::mapping<E> m2;
+ [[maybe_unused]] typename Layout<128>::mapping<E> m3;
+ [[maybe_unused]] typename Layout<255>::mapping<E> m4;
+ }
+ return true;
+ }
+
+template<typename Layout, typename CanonicalExtents>
+ constexpr void
+ test_default_ctor_single(auto canonical_strides)
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_typename<Layout>()>;
+ using E = typename Traits::extents_type<CanonicalExtents>;
+ auto strides = Traits::make_array(canonical_strides);
+
+ typename Layout::template mapping<E> msta;
+ VERIFY(msta.stride(0) == strides[0]);
+ VERIFY(msta.stride(1) == strides[1]);
+ }
+
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_default_ctor()
+ {
+ using E1 = std::extents<size_t, 3, 5>;
+ test_default_ctor_single<Layout<2>, E1>(std::array<size_t, 2>{1, 4});
+ test_default_ctor_single<Layout<dyn>, E1>(std::array<size_t, 2>{1, 3});
+
+ using E2 = std::extents<size_t, dyn, 5>;
+ test_default_ctor_single<Layout<2>, E2>(std::array<size_t, 2>{1, 0});
+ test_default_ctor_single<Layout<dyn>, E2>(std::array<size_t, 2>{1, 0});
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_exts()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto exts = Traits::make_extents(std::dextents<size_t, 2>{3, 5});
+
+ typename Layout<0>::mapping m0_sta(exts);
+ VERIFY(Traits::padded_stride(m0_sta) == Traits::padded_extent(exts));
+
+ typename Layout<1>::mapping m1_sta(exts);
+ VERIFY(Traits::padded_stride(m1_sta) == Traits::padded_extent(exts));
+
+ typename Layout<2>::mapping m2_sta(exts);
+ VERIFY(Traits::padded_stride(m2_sta) == 4);
+
+ typename Layout<dyn>::mapping mdyn(exts);
+ VERIFY(Traits::padded_stride(mdyn) == Traits::padded_extent(exts));
+ return true;
+ }
+
+template<typename Layout, typename CustomPadType>
+ constexpr bool
+ test_from_pad_single()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_typename<Layout>()>;
+ auto pad = 3;
+ auto exts = Traits::make_extents(std::dextents<size_t, 3>{pad + 1, 5, 7});
+ typename Layout::mapping m(exts, CustomPadType{pad});
+ VERIFY(std::cmp_equal(Traits::padded_stride(m), 2*pad));
+ VERIFY(m.extents() == exts);
+ return true;
+ }
+
+template<typename Layout>
+ constexpr void
+ test_from_pad()
+ {
+ test_from_pad_single<Layout, int>();
+ static_assert(test_from_pad_single<Layout, int>());
+
+ test_from_pad_single<Layout, IntLike>();
+ test_from_pad_single<Layout, MutatingInt>();
+ test_from_pad_single<Layout, RValueInt>();
+
+ using Extents = std::dims<3>;
+ using Mapping = Layout::template mapping<Extents>;
+ static_assert(!std::is_constructible_v<Mapping, Extents, ThrowingInt>);
+ static_assert(!std::is_constructible_v<Mapping, Extents, NotIntLike>);
+ }
+
+template<template<size_t> typename Layout>
+ constexpr void
+ test_from_pad_all()
+ {
+ test_from_pad<Layout<3>>();
+ test_from_pad<Layout<dyn>>();
+ }
+
+constexpr bool
+is_same_mapping(const auto& lhs, const auto& rhs)
+{
+ if (lhs.extents().rank() != rhs.extents().rank())
+ return false;
+
+ if (lhs.extents() != rhs.extents())
+ return false;
+
+ for (size_t i = 0; i < lhs.extents().rank(); ++i)
+ if (lhs.stride(i) != rhs.stride(i))
+ return false;
+ return true;
+}
+
+enum class ConversionRule
+{
+ Never,
+ Always,
+ Regular
+};
+
+template<typename To, typename From>
+consteval bool
+should_convert(auto rule)
+{
+ if constexpr (rule == ConversionRule::Never)
+ return false;
+ if constexpr (rule == ConversionRule::Always)
+ return true;
+ else
+ return std::is_convertible_v<typename From::extents_type,
+ typename To::extents_type>;
+}
+
+template<typename To, typename From>
+ constexpr void
+ check_convertible(const From& m, auto conversion_rule)
+ {
+ VERIFY(is_same_mapping(m, To(m)));
+ constexpr bool expected = should_convert<To, From>(conversion_rule);
+ static_assert(std::is_convertible_v<From, To> == expected);
+ }
+
+template<typename LayoutTo, typename Esta, typename Edyn, typename Ewrong>
+ constexpr void
+ check_convertible_variants(auto msta, auto conversion_rule)
+ {
+ using LayoutFrom = decltype(msta)::layout_type;
+ constexpr auto cregular = std::cw<ConversionRule::Regular>;
+
+ // There's a twist when both mappings are left-padded. There's two distinct
+ // ctors: a defaulted copy ctor and a constrained template that enables
+ // construction from left-padded mappings even if their layout_type is
+ // different. The two ctors have different rules regarding conversion.
+
+ if constexpr (!std::same_as<LayoutTo, LayoutFrom>)
+ check_convertible<typename LayoutTo::mapping<Esta>>(msta,
conversion_rule);
+ else
+ check_convertible<typename LayoutTo::mapping<Esta>>(msta, cregular);
+
+ check_convertible<typename LayoutTo::mapping<Edyn>>(msta, conversion_rule);
+
+ auto mdyn = typename LayoutFrom::mapping<Edyn>(msta);
+ check_convertible<typename LayoutTo::mapping<Esta>>(mdyn, conversion_rule);
+ if constexpr (!std::same_as<LayoutTo, LayoutFrom>)
+ check_convertible<typename LayoutTo::mapping<Edyn>>(mdyn,
conversion_rule);
+ else
+ check_convertible<typename LayoutTo::mapping<Edyn>>(mdyn, cregular);
+
+ static_assert(!std::is_constructible_v<
+ typename LayoutTo::mapping<Esta>, typename
LayoutFrom::mapping<Ewrong>>);
+ };
+
+template<typename Layout>
+ constexpr void
+ test_from_same_1d()
+ {
+ using E1 = std::extents<int, 6>;
+ using E2 = std::extents<int, dyn>;
+ using E3 = std::extents<int, 5>;
+ constexpr auto cr = std::cw<ConversionRule::Regular>;
+
+ using Traits = LayoutTraits<DeducePaddingSide::from_typename<Layout>()>;
+ auto msta = typename Traits::layout_same::mapping(E1{});
+ check_convertible_variants<Layout, E1, E2, E3>(msta, cr);
+ }
+
+template<typename Layout>
+ constexpr void
+ test_from_same_2d()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_typename<Layout>()>;
+ using E1 = typename Traits::extents_type<std::extents<int, 6, 5>>;
+ using E2 = typename Traits::extents_type<std::extents<int, dyn, 5>>;
+ using E3 = typename Traits::extents_type<std::extents<int, 6, 6>>;
+ constexpr auto cr = std::cw<ConversionRule::Regular>;
+
+ auto msta = typename Traits::layout_same::mapping(E1{});
+ check_convertible_variants<Layout, E1, E2, E3>(msta, cr);
+ }
+
+template<template<size_t> typename Layout>
+constexpr bool
+test_from_same()
+{
+ auto check = []<typename PaddedLayout>(PaddedLayout)
+ {
+ test_from_same_1d<PaddedLayout>();
+ test_from_same_2d<PaddedLayout>();
+ };
+
+ check(Layout<0>{});
+ check(Layout<1>{});
+ check(Layout<2>{});
+ check(Layout<6>{});
+ check(Layout<dyn>{});
+
+ // rank == 1 is more permissive:
+ test_from_same_1d<Layout<5>>();
+ return true;
+}
+
+template<template<size_t> typename Layout, typename E1_, typename E2_,
+ typename E3_>
+ constexpr bool
+ test_from_stride_nd(auto strides_)
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using E1 = typename Traits::extents_type<E1_>;
+ using E2 = typename Traits::extents_type<E2_>;
+ using E3 = typename Traits::extents_type<E3_>;
+ auto strides = Traits::make_array(strides_);
+
+ auto check = [&strides]<typename PaddedLayout>(PaddedLayout)
+ {
+ auto exts = E1{};
+ constexpr auto cr = std::cw<ConversionRule::Never>;
+
+ auto m = std::layout_stride::mapping(exts, strides);
+ check_convertible_variants<PaddedLayout, E1, E2, E3>(m, cr);
+ };
+
+ check(Layout<0>{});
+ check(Layout<1>{});
+ check(Layout<2>{});
+ check(Layout<6>{});
+ check(Layout<dyn>{});
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_stride_2d()
+ {
+ using E1 = std::extents<size_t, 6, 5>;
+ using E2 = std::dims<2>;
+ using E3 = std::extents<size_t, 6, 6>;
+
+ auto strides = std::array<int, 2>{1, 6};
+ test_from_stride_nd<Layout, E1, E2, E3>(strides);
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_stride_3d()
+ {
+ using E1 = std::extents<size_t, 6, 5, 7>;
+ using E2 = std::dims<3>;
+ using E3 = std::extents<size_t, 6, 6, 7>;
+
+ auto strides = std::array<int, 3>{1, 6, 6*5};
+ test_from_stride_nd<Layout, E1, E2, E3>(strides);
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_stride()
+ {
+ test_from_stride_2d<Layout>();
+ test_from_stride_3d<Layout>();
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr void
+ test_from_samepad_0d()
+ {
+ using E1 = std::extents<uint16_t>;
+ using E2 = std::extents<uint8_t>;
+ using E3 = std::extents<uint8_t, 1>;
+
+ typename Layout<6>::mapping<E1> msta{E1{}};
+
+ auto check = []<typename To>(To, auto m)
+ {
+ constexpr auto cr = std::cw<ConversionRule::Always>;
+ check_convertible_variants<To, E1, E2, E3>(m, cr);
+ };
+
+ check(Layout<6>{}, msta);
+ check(Layout<dyn>{}, msta);
+ }
+
+template<template<size_t> typename Layout>
+ constexpr void
+ test_from_samepad_1d()
+ {
+ using E1 = std::extents<int, 6>;
+ using E2 = std::extents<int, dyn>;
+ using E3 = std::extents<int, 6, 6>;
+
+ typename Layout<6>::mapping<E1> msta{E1{}};
+ typename Layout<dyn>::mapping<E1> mdyn{E1{}};
+
+ auto check = []<typename To>(To, auto m)
+ {
+ constexpr auto cr = std::cw<ConversionRule::Always>;
+ check_convertible_variants<To, E1, E2, E3>(m, cr);
+ };
+
+ // Remember, for rank <= 1 the padding_value is irrelevant.
+ check(Layout<6>{}, msta);
+ check(Layout<6>{}, mdyn);
+ check(Layout<dyn>{}, msta);
+ check(Layout<dyn>{}, mdyn);
+ }
+
+template<template<size_t> typename Layout>
+ constexpr void
+ test_from_samepad_2d()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using E1 = typename Traits::extents_type<std::extents<int, 6, 5>>;
+ using E2 = typename Traits::extents_type<std::extents<int, dyn, 5>>;
+ using E3 = typename Traits::extents_type<std::extents<int, 6, 6>>;
+
+ typename Layout<6>::mapping<E1> msta{E1{}};
+ typename Layout<dyn>::mapping<E1> mdyn{E1{}};
+
+ constexpr auto calways = std::cw<ConversionRule::Always>;
+ constexpr auto cnever = std::cw<ConversionRule::Never>;
+
+ auto check = []<typename To>(To, auto m, auto cr)
+ { check_convertible_variants<To, E1, E2, E3>(m, cr); };
+
+ check(Layout<6>{}, msta, cnever);
+ check(Layout<6>{}, mdyn, cnever);
+ check(Layout<dyn>{}, msta, calways);
+ check(Layout<dyn>{}, mdyn, cnever);
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_samepad()
+ {
+ test_from_samepad_0d<Layout>();
+ test_from_samepad_1d<Layout>();
+ test_from_samepad_2d<Layout>();
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_other()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using E1 = std::extents<size_t, 3>;
+ using E2 = std::dims<1>;
+ using E3 = std::extents<size_t, 5>;
+
+ auto check = []<typename PaddedLayout>(PaddedLayout)
+ {
+ constexpr auto cr = std::cw<ConversionRule::Regular>;
+
+ using layout_other = typename Traits::layout_other;
+ auto msta = typename layout_other::mapping(E1{});
+ check_convertible_variants<PaddedLayout, E1, E2, E3>(msta, cr);
+ };
+
+
+ // Remember, the padding_value has no effect for rank <= 1.
+ check(Layout<0>{});
+ check(Layout<1>{});
+ check(Layout<2>{});
+ check(Layout<5>{});
+ check(Layout<6>{});
+ check(Layout<dyn>{});
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_to_same()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using E1 = typename Traits::extents_type<std::extents<int, 6, 5>>;
+ using E2 = typename Traits::extents_type<std::extents<int, dyn, 5>>;
+ using E3 = typename Traits::extents_type<std::extents<int, 6, 6>>;
+
+ auto check = [](auto msta)
+ {
+ constexpr auto cr = std::cw<ConversionRule::Regular>;
+ using LayoutSame = typename Traits::layout_same;
+ check_convertible_variants<LayoutSame, E1, E2, E3>(msta, cr);
+ };
+
+ check(typename Layout<0>::mapping(E1{}));
+ check(typename Layout<2>::mapping(E1{}));
+ check(typename Layout<6>::mapping(E1{}));
+ check(typename Layout<dyn>::mapping(E1{}, 0));
+ check(typename Layout<dyn>::mapping(E1{}, 2));
+ check(typename Layout<dyn>::mapping(E1{}, 6));
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_never_to_other()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using E1 = std::extents<size_t, 3>;
+ using E2 = std::dims<1>;
+
+ auto check = []<typename PaddedLayout>(PaddedLayout, auto exts)
+ {
+ using LayoutOther = typename Traits::layout_other;
+ auto mr = typename LayoutOther::mapping(exts);
+ auto mlp = typename PaddedLayout::mapping<decltype(exts)>{mr};
+ static_assert(!std::is_constructible_v<decltype(mr), decltype(mlp)>);
+ };
+
+ check(Layout<2>{}, E1{});
+ check(Layout<2>{}, E2{E1{}});
+ return true;
+ }
+
+template<typename Layout>
+ constexpr void
+ test_strides()
+ {
+ auto check = [](auto exts)
+ {
+ auto m = typename Layout::mapping(exts);
+ using IndexType = typename decltype(m)::index_type;
+ constexpr size_t rank = decltype(m)::extents_type::rank();
+
+ auto strides = m.strides();
+ static_assert(std::same_as<decltype(strides),
+ std::array<IndexType, rank>>);
+ VERIFY(strides.size() == rank);
+ for (size_t i = 0; i < strides.size(); ++i)
+ VERIFY(strides[i] == m.stride(i));
+ };
+
+ check(std::extents());
+ check(std::extents(0));
+ check(std::extents(3));
+ check(std::extents(3, 5, 7));
+ check(std::extents(3, 0, 7));
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_strides_all()
+ {
+ test_strides<Layout<0>>();
+ test_strides<Layout<1>>();
+ test_strides<Layout<3>>();
+ test_strides<Layout<dyn>>();
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr void
+ test_exhaustive_0d()
+ {
+ auto exts = std::extents<int>{};
+
+ auto check = [](auto m)
+ {
+ static_assert(m.is_always_exhaustive());
+ VERIFY(m.is_exhaustive());
+ };
+
+ check(typename Layout<0>::mapping(exts));
+ check(typename Layout<1>::mapping(exts));
+ check(typename Layout<2>::mapping(exts));
+ check(typename Layout<dyn>::mapping(exts));
+ }
+
+template<template<size_t> typename Layout>
+constexpr void
+ test_exhaustive_1d()
+ {
+ auto check_dyn_and_sta = []<typename PaddedLayout>(PaddedLayout)
+ {
+ auto check = [](auto exts)
+ {
+ auto m = typename PaddedLayout::mapping(exts);
+ static_assert(m.is_always_exhaustive());
+ VERIFY(m.is_exhaustive());
+ };
+
+ check(std::extents(4));
+ check(std::extents<int, 4>{});
+ };
+
+ check_dyn_and_sta(Layout<1>{});
+ check_dyn_and_sta(Layout<2>{});
+ check_dyn_and_sta(Layout<6>{});
+ check_dyn_and_sta(Layout<dyn>{});
+ }
+
+template<template<size_t> typename Layout>
+ constexpr void
+ test_exhaustive_3d()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto exts_dyn = Traits::make_extents(std::extents(4, 5, 7));
+ auto exts_sta = Traits::make_extents(std::extents<int, 4, 5, 7>{});
+ auto ctrue = std::cw<true>;
+ auto cfalse= std::cw<false>;
+
+ auto check = [](auto m, auto static_expected, auto runtime_expected)
+ {
+ static_assert(m.is_always_exhaustive() == static_expected);
+ VERIFY(m.is_exhaustive() == runtime_expected);
+ };
+
+ check(typename Layout<0>::mapping(exts_sta), ctrue, true);
+ check(typename Layout<0>::mapping(exts_dyn), cfalse, true);
+ check(typename Layout<1>::mapping(exts_sta), ctrue, true);
+ check(typename Layout<1>::mapping(exts_dyn), cfalse, true);
+ check(typename Layout<2>::mapping(exts_sta), ctrue, true);
+ check(typename Layout<2>::mapping(exts_dyn), cfalse, true);
+ check(typename Layout<6>::mapping(exts_dyn), cfalse, false);
+ check(typename Layout<6>::mapping(exts_sta), cfalse, false);
+ check(typename Layout<dyn>::mapping(exts_sta), cfalse, true);
+ check(typename Layout<dyn>::mapping(exts_dyn, 2), cfalse, true);
+ check(typename Layout<dyn>::mapping(exts_dyn, 3), cfalse, false);
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_exhaustive()
+ {
+ test_exhaustive_0d<Layout>();
+ test_exhaustive_1d<Layout>();
+ test_exhaustive_3d<Layout>();
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_op_eq()
+ {
+ // The generic cases are handled in layouts/mapping.cc. Here we check
+ // special cases related to non exhaustive layouts.
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+
+ auto exts_sta = Traits::make_extents(std::extents<size_t, 6, 5, 7>{});
+ auto exts_dyn = std::dims<3>(exts_sta);
+ auto exts_other = Traits::make_extents(std::extents<size_t, 7, 5, 7>{});
+
+ auto m1 = typename Layout<0>::mapping(exts_sta);
+ auto m2 = typename Layout<7>::mapping(exts_sta);
+
+ VERIFY(m1 == typename Layout<0>::mapping(exts_sta));
+ VERIFY(m1 == typename Layout<1>::mapping(exts_sta));
+ VERIFY(m1 == typename Layout<2>::mapping(exts_sta));
+ VERIFY(m1 == typename Layout<6>::mapping(exts_sta));
+ VERIFY(m1 != typename Layout<7>::mapping(exts_sta));
+ VERIFY(m1 == typename Layout<dyn>::mapping(exts_sta));
+ VERIFY(m1 != typename Layout<dyn>::mapping(exts_sta, 7));
+
+ VERIFY(m1 == typename Layout<0>::mapping(exts_dyn));
+ VERIFY(m1 == typename Layout<1>::mapping(exts_dyn));
+ VERIFY(m1 == typename Layout<2>::mapping(exts_dyn));
+ VERIFY(m1 == typename Layout<6>::mapping(exts_dyn));
+ VERIFY(m1 != typename Layout<7>::mapping(exts_dyn));
+ VERIFY(m1 == typename Layout<dyn>::mapping(exts_dyn));
+ VERIFY(m1 != typename Layout<dyn>::mapping(exts_dyn, 7));
+
+ VERIFY(m2 == typename Layout<7>::mapping(exts_sta));
+ VERIFY(m2 == typename Layout<dyn>::mapping(exts_sta, 7));
+ VERIFY(m2 == typename Layout<7>::mapping(exts_dyn));
+ VERIFY(m2 == typename Layout<dyn>::mapping(exts_dyn, 7));
+
+ VERIFY(m2 != typename Layout<7>::mapping(exts_other));
+ VERIFY(m2 != typename Layout<dyn>::mapping(exts_other, 7));
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_required_span_size_overflow()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using Extents = std::dextents<uint8_t, 2>;
+ auto exts = Traits::make_extents(Extents{64, 2});
+ auto strides = Traits::make_array(std::array<uint8_t, 2>{1, 128});
+ auto ms = std::layout_stride::mapping(exts, strides);
+ auto m = typename Layout<dyn>::mapping<Extents>(ms);
+ VERIFY(is_same_mapping(m, ms));
+ VERIFY(m.required_span_size() == ms.required_span_size());
+ return true;
+ }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_all()
+ {
+ test_representable_padded_size<std::layout_left_padded>();
+ test_default_ctor<Layout>();
+ test_from_exts<Layout>();
+ test_from_stride<Layout>();
+ test_from_samepad<Layout>();
+ test_from_same<Layout>();
+ test_from_other<Layout>();
+ test_to_same<Layout>();
+ test_never_to_other<Layout>();
+ test_strides_all<Layout>();
+ test_exhaustive<Layout>();
+ test_op_eq<Layout>();
+ test_required_span_size_overflow<Layout>();
+ return true;
+ }
+
+int
+main()
+{
+ test_all<std::layout_left_padded>();
+ static_assert(test_all<std::layout_left_padded>());
+
+ test_from_pad_all<std::layout_left_padded>();
+ return 0;
+}
diff --git a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_neg.cc
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_neg.cc
new file mode 100644
index 00000000000..f0dbfe9d9c6
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_neg.cc
@@ -0,0 +1,324 @@
+// { dg-do compile { target c++26 } }
+#include <mdspan>
+
+#include "padded_traits.h"
+#include <cstdint>
+
+constexpr size_t dyn = std::dynamic_extent;
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_extens_representable_sta()
+ {
+ using E1 = std::extents<uint8_t, 8, 128>;
+ auto m = typename Layout<dyn>::mapping(E1{}); // { dg-error "required
from" }
+ return true;
+ }
+static_assert(test_from_extens_representable_sta<std::layout_left_padded>());
// { dg-error "from here" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_extents_representable_padded_size()
+ {
+ using E1 = std::extents<uint8_t, 8, 128>;
+ using E2 = std::dextents<uint8_t, 2>;
+
+ auto m = typename Layout<dyn>::mapping(E2{E1{}}); // { dg-error "expansion
of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_extents_representable_padded_size<std::layout_left_padded>());
// { dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_extents_representable_stride()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using E1 = typename Traits::extents_type<std::extents<uint8_t, dyn, 1>>;
+ auto m = typename Layout<128>::mapping(E1{129}); // { dg-error "expansion
of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_extents_representable_stride<std::layout_left_padded>());
// { dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_pad_representable_stride()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto exts = Traits::make_extents(std::dextents<uint8_t, 2>(129, 2));
+ auto m = typename Layout<dyn>::mapping(exts, 128); // { dg-error
"expansion of" }
+ return true;
+ }
+static_assert(test_from_pad_representable_stride<std::layout_left_padded>());
// { dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_pad_representable_padded_size()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto exts = Traits::make_extents(std::dextents<uint8_t, 2>(64, 2));
+ auto m = typename Layout<dyn>::mapping(exts, 128); // { dg-error
"expansion of" }
+ return true;
+ }
+static_assert(test_from_pad_representable_padded_size<std::layout_left_padded>());
// { dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_left()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using LayoutSame = typename Traits::layout_same;
+ auto exts = Traits::make_extents(std::extents<uint8_t, 6, dyn>{4});
+ auto ml = typename LayoutSame::mapping(exts);
+
+ typename Layout<4>::mapping<decltype(exts)> m(ml); // { dg-error
"expansion of" }
+ return true;
+ }
+static_assert(test_from_left<std::layout_left_padded>()); // { dg-error
"required from here" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_left_bad_runtime_stride()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto exts = Traits::make_extents(std::extents<uint8_t, dyn, dyn>{6, 4});
+ auto ml = typename Traits::layout_same::mapping(exts);
+
+ typename Layout<4>::mapping<decltype(exts)> m(ml); // { dg-error
"expansion of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_left_bad_runtime_stride<std::layout_left_padded>());
// { dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_left_representable_extents()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto exts = Traits::make_extents(std::extents<uint16_t, dyn, dyn>{8, 128});
+ auto ml = typename Traits::layout_same::mapping(exts);
+
+ typename Layout<8>::mapping<std::extents<uint8_t, dyn, dyn>> m(ml); // {
dg-error "expansion of" }
+ return true;
+ }
+static_assert(test_from_left_representable_extents<std::layout_left_padded>());
// { dg-error "expansion of" }
+
+template<template<size_t> typename Layout, size_t PaddingValue>
+ constexpr bool
+ test_pad_overflow()
+ {
+ auto exts = std::extents<uint8_t, dyn>{4};
+ auto n = size_t(1) << 9;
+ auto m = typename Layout<PaddingValue>::mapping(exts, n);
+ (void) m;
+ return true;
+ }
+static_assert(test_pad_overflow<std::layout_left_padded, 1>()); // {
dg-error "expansion of" }
+static_assert(test_pad_overflow<std::layout_left_padded, dyn>()); // {
dg-error "expansion of" }
+
+template<template<size_t> typename Layout, size_t PaddingValue>
+ constexpr bool
+ test_from_pad_negative()
+ {
+ auto exts = std::extents(4);
+ auto m = typename Layout<PaddingValue>::mapping(exts, -1);
+ (void) m;
+ return true;
+ }
+static_assert(test_from_pad_negative<std::layout_left_padded, 1>()); // {
dg-error "expansion of" }
+static_assert(test_from_pad_negative<std::layout_left_padded, dyn>()); // {
dg-error "expansion of" }
+
+template<template<size_t> typename Layout, size_t Pad>
+ constexpr bool
+ test_static_pad_same()
+ {
+ using Extents = std::extents<int, dyn>;
+ using Mapping = typename Layout<Pad>::mapping<Extents>;
+ auto exts = Extents{4};
+ auto m = Mapping(exts, Pad + 1); // { dg-error "expansion of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_static_pad_same<std::layout_left_padded, 1>()); // {
dg-error "expansion of" }
+static_assert(test_static_pad_same<std::layout_left_padded, 3>()); // {
dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_stride_wrong_stride0()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto e = Traits::make_extents(std::extents{3, 5});
+ auto s = Traits::make_array(std::array<int, 2>{2, 7});
+ auto ms = std::layout_stride::mapping(e, s);
+ auto m = typename Layout<dyn>::mapping<decltype(e)>(ms); // { dg-error
"expansion of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_stride_wrong_stride0<std::layout_left_padded>()); // {
dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_stride_wrong_stride1()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto e = Traits::make_extents(std::extents(3, 5));
+ auto s = Traits::make_array(std::array<int, 2>{1, 3});
+ auto ms = std::layout_stride::mapping(e, s);
+ auto m = typename Layout<2>::mapping<decltype(e)>(ms); // { dg-error
"expansion of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_stride_wrong_stride1<std::layout_left_padded>()); // {
dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_stride_wrong_stride2()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto e = Traits::make_extents(std::extents(3, 5, 7));
+ auto s = Traits::make_array(std::array<int, 3>{1, 4, 21});
+ auto ms = std::layout_stride::mapping(e, s);
+ auto m = typename Layout<dyn>::mapping<decltype(e)>(ms); // here (not
implemented)
+ (void) m;
+ return true;
+ }
+static_assert(test_from_stride_wrong_stride2<std::layout_left_padded>());
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_stride_oversized()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto exts = Traits::make_extents(std::extents<uint16_t, dyn, dyn>{3, 6});
+ auto s = Traits::make_array(std::array<uint16_t, 2>{1, 128});
+ auto ms = std::layout_stride::mapping(exts, s);
+
+ using Mapping = typename Layout<dyn>::mapping<std::dextents<uint8_t, 2>>;
+ Mapping m(ms); // { dg-error "expansion of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_stride_oversized<std::layout_left_padded>()); // {
dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_samepad_dyn()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto e = Traits::make_extents(std::extents(3, 5));
+ auto mlp = typename Layout<dyn>::mapping(e);
+ auto m = typename Layout<2>::mapping<decltype(e)>(mlp); // { dg-error
"expansion of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_samepad_dyn<std::layout_left_padded>()); // { dg-error
"expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_samepad_sta()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ auto e = Traits::make_extents(std::extents{3, 5});
+ auto mlp = typename Layout<3>::mapping(e);
+ auto m = typename Layout<2>::mapping<decltype(e)>(mlp); // { dg-error
"expansion of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_samepad_sta<std::layout_left_padded>()); // { dg-error
"expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_from_samepad_oversized()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using E1 = typename Traits::extents_type<std::extents<uint16_t, 8, 128>>;
+ using E2 = typename Traits::extents_type<std::extents<uint8_t, dyn, dyn>>;
+ auto mlp = typename Layout<dyn>::mapping<E1>(E1{});
+ auto m = typename Layout<dyn>::mapping<E2>(mlp); // { dg-error "expansion
of" }
+ (void) m;
+ return true;
+ }
+static_assert(test_from_samepad_oversized<std::layout_left_padded>()); // {
dg-error "expansion of" }
+
+template<template<size_t> typename Layout, size_t RunId>
+ constexpr bool
+ test_to_same_not_exhaustive()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using E1 = typename Traits::extents_type<std::extents<int, 6, 5>>;
+ using E2 = typename Traits::extents_type<std::extents<int, dyn, 5>>;
+
+ [[maybe_unused]] auto msta = typename Layout<7>::mapping(E1{});
+ if constexpr (RunId == 0)
+ {
+ auto m = typename Traits::layout_same::mapping<E1>(msta); // { dg-error
"required from" }
+ (void) m;
+ }
+ if constexpr (RunId == 1)
+ {
+ auto m = typename Traits::layout_same::mapping<E2>(msta); // { dg-error
"expansion of" }
+ (void) m;
+ }
+
+ [[maybe_unused]] auto mdyn = typename Layout<dyn>::mapping(E2{E1{}}, 7);
+ if constexpr (RunId == 2)
+ {
+ auto m = typename Traits::layout_same::mapping<E1>(mdyn); // { dg-error
"expansion of" }
+ (void) m;
+ }
+ if constexpr (RunId == 3)
+ {
+ auto m = typename Traits::layout_same::mapping<E2>(mdyn); // { dg-error
"expansion of" }
+ (void) m;
+ }
+ return true;
+ }
+static_assert(test_to_same_not_exhaustive<std::layout_left_padded, 0>()); // {
dg-error "expansion of" }
+static_assert(test_to_same_not_exhaustive<std::layout_left_padded, 1>()); // {
dg-error "expansion of" }
+static_assert(test_to_same_not_exhaustive<std::layout_left_padded, 2>()); // {
dg-error "expansion of" }
+static_assert(test_to_same_not_exhaustive<std::layout_left_padded, 3>()); // {
dg-error "expansion of" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_statically_bad_padding_value1()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ constexpr auto N = std::numeric_limits<size_t>::max() - 1;
+ using Extents = typename Traits::extents_type<std::extents<size_t, N, 0>>;
+ typename Layout<10>::mapping<Extents> m; // { dg-error "required from" }
+ return true;
+ }
+static_assert(test_statically_bad_padding_value1<std::layout_left_padded>());
// { dg-error "required from" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_statically_bad_padding_value2()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using Extents = typename Traits::extents_type<std::extents<uint8_t, 255,
0>>;
+ typename Layout<2>::mapping<Extents> m; // { dg-error "required from" }
+ return true;
+ }
+static_assert(test_statically_bad_padding_value2<std::layout_left_padded>());
// { dg-error "required from" }
+
+template<template<size_t> typename Layout>
+ constexpr bool
+ test_statically_oversized()
+ {
+ using Traits = LayoutTraits<DeducePaddingSide::from_template<Layout>()>;
+ using Extents = typename Traits::extents_type<std::extents<uint8_t, 127,
2>>;
+ typename Layout<2>::mapping<Extents> m; // { dg-error "required from" }
+ return true;
+ }
+static_assert(test_statically_oversized<std::layout_left_padded>()); // {
dg-error "from here" }
+
+// { dg-prune-output "padding_value must be representable as index_type" }
+// { dg-prune-output "non-constant condition for static assertion" }
+// { dg-prune-output "called in a constant expression" }
+// { dg-prune-output "no matching function" }
+// { dg-prune-output "static assertion failed" }
+// { dg-prune-output "__glibcxx_assert_fail()" }
+// { dg-prune-output "must be compatible with other.stride" }
+// { dg-prune-output "padding_value is dynamic_extent" }
+// { dg-prune-output "_S_rank <= 1" }
diff --git
a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_traits.h
b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_traits.h
new file mode 100644
index 00000000000..9171d8c1ce1
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/padded_traits.h
@@ -0,0 +1,73 @@
+#ifndef TEST_MDSPAN_PADDED_TRAITS_H
+#define TEST_MDSPAN_PADDED_TRAITS_H
+
+#include <algorithm>
+
+template<typename Layout>
+ constexpr static bool is_left_padded = false;
+
+#if __cplusplus > 202302L
+template<size_t PaddingValue>
+ constexpr static bool is_left_padded<std::layout_left_padded<PaddingValue>>
+ = true;
+#endif
+
+template<typename Layout>
+ constexpr bool
+ is_padded_layout = is_left_padded<Layout>;
+
+#if __cplusplus > 202302L
+
+enum class PaddingSide
+{
+ Left
+};
+
+struct DeducePaddingSide
+{
+ template<template<size_t> typename Layout>
+ constexpr static PaddingSide
+ from_template()
+ { return PaddingSide::Left; }
+
+ template<typename Layout>
+ constexpr static PaddingSide
+ from_typename()
+ { return PaddingSide::Left; }
+};
+
+template<PaddingSide Side>
+ struct LayoutTraits;
+
+template<>
+ struct LayoutTraits<PaddingSide::Left>
+ {
+ using layout_same = std::layout_left;
+ using layout_other = std::layout_right;
+
+ template<typename Extents>
+ using extents_type = Extents;
+
+ template<typename Extents>
+ constexpr static extents_type<Extents>
+ make_extents(const Extents& exts)
+ { return exts; }
+
+ template<typename T, size_t N>
+ constexpr static std::array<T, N>
+ make_array(const std::array<T, N>& expected)
+ { return expected; }
+
+ template<typename Mapping>
+ constexpr static auto
+ padded_stride(const Mapping& m)
+ { return m.stride(1); }
+
+ template<typename Extents>
+ constexpr static auto
+ padded_extent(const Extents& exts)
+ { return exts.extent(0); }
+ };
+
+#endif
+#endif
--
2.50.1
