On Mon, 8 Dec 2025 at 22:27, Luc Grosheintz <[email protected]> wrote: > > Add submdspan_mapping for layout_stride as in P3663.
OK > > PR libstdc++/110352 > > libstdc++-v3/ChangeLog: > > * include/std/mdspan (layout_stride::mapping::submdspan_mapping): New > friend function. > * testsuite/23_containers/mdspan/submdspan/selections/stride.cc: > Instantiate tests for layout_stride. > * testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc: > Ditto. > * testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc: > Add tests for layout_stride. > > Signed-off-by: Luc Grosheintz <[email protected]> > --- > libstdc++-v3/include/std/mdspan | 20 +++++++++++++++++++ > .../mdspan/submdspan/selections/stride.cc | 9 +++++++++ > .../mdspan/submdspan/submdspan_mapping.cc | 18 +++++++++++++++++ > .../mdspan/submdspan/submdspan_neg.cc | 9 +++++++++ > 4 files changed, 56 insertions(+) > create mode 100644 > libstdc++-v3/testsuite/23_containers/mdspan/submdspan/selections/stride.cc > > diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan > index c962d0e0cd3..16dda4c8468 100644 > --- a/libstdc++-v3/include/std/mdspan > +++ b/libstdc++-v3/include/std/mdspan > @@ -1928,6 +1928,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > } > > private: > +#if __glibcxx_submdspan > + template<typename... _Slices> > + requires (extents_type::rank() == sizeof...(_Slices)) > + friend constexpr auto > + submdspan_mapping(const mapping& __mapping, _Slices... __slices) > + { > + if constexpr (sizeof...(_Slices) == 0) > + return submdspan_mapping_result{__mapping, 0}; > + else > + { > + auto __offset = __mdspan::__suboffset(__mapping, __slices...); > + auto __sub_exts = __mdspan::__subextents(__mapping.extents(), > __slices...); > + auto __sub_strides > + = __mdspan::__substrides<decltype(__sub_exts)>(__mapping, > __slices...); > + return submdspan_mapping_result{ > + layout_stride::mapping(__sub_exts, __sub_strides), __offset}; > + } > + } > +#endif > + > using _Strides = typename __array_traits<index_type, > extents_type::rank()>::_Type; > [[no_unique_address]] extents_type _M_extents; > diff --git > a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/selections/stride.cc > b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/selections/stride.cc > new file mode 100644 > index 00000000000..19451d7f954 > --- /dev/null > +++ > b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/selections/stride.cc > @@ -0,0 +1,9 @@ > +// { dg-do run { target c++26 } } > +#include "testcases.h" > + > +int > +main() > +{ > + test_all<std::layout_stride>(); > + return 0; > +} > diff --git > a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc > b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc > index cc832cdb415..cf6167dc3b0 100644 > --- > a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc > +++ > b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_mapping.cc > @@ -123,6 +123,21 @@ template<typename Layout> > return true; > } > > +constexpr bool > +test_layout_stride_return_types() > +{ > + auto exts = std::extents(3, 5); > + auto m = std::layout_stride::mapping(exts, std::array{2, 12}); > + > + using index_type = decltype(exts)::index_type; > + auto s1 = std::strided_slice{index_type(2), index_type(2), > + std::cw<index_type(2)>}; > + auto result = submdspan_mapping(m, index_type(1), s1); > + using layout_type = decltype(result.mapping)::layout_type; > + static_assert(std::same_as<layout_type, std::layout_stride>); > + return true; > +} > + > int > main() > { > @@ -132,6 +147,9 @@ main() > test_layout_unpadded_return_types<std::layout_right>(); > static_assert(test_layout_unpadded_return_types<std::layout_right>()); > > + test_layout_stride_return_types(); > + static_assert(test_layout_stride_return_types()); > + > test_layout_unpadded_padding_value<std::layout_left>(); > static_assert(test_layout_unpadded_padding_value<std::layout_left>()); > > diff --git > a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc > b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc > index 15b9b2e71ec..39eb18cb03d 100644 > --- a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc > +++ b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_neg.cc > @@ -25,6 +25,7 @@ template<typename Layout> > } > static_assert(test_int_under<std::layout_left>()); // { dg-error > "expansion of" } > static_assert(test_int_under<std::layout_right>()); // { dg-error > "expansion of" } > +static_assert(test_int_under<std::layout_stride>()); // { dg-error > "expansion of" } > > template<typename Layout> > constexpr bool > @@ -35,6 +36,7 @@ template<typename Layout> > } > static_assert(test_int_over<std::layout_left>()); // { dg-error > "expansion of" } > static_assert(test_int_over<std::layout_right>()); // { dg-error > "expansion of" } > +static_assert(test_int_over<std::layout_stride>()); // { dg-error > "expansion of" } > > template<typename Layout> > constexpr bool > @@ -45,6 +47,7 @@ template<typename Layout> > } > static_assert(test_tuple_under<std::layout_left>()); // { dg-error > "expansion of" } > static_assert(test_tuple_under<std::layout_right>()); // { dg-error > "expansion of" } > +static_assert(test_tuple_under<std::layout_stride>()); // { dg-error > "expansion of" } > > template<typename Layout> > constexpr bool > @@ -55,6 +58,7 @@ template<typename Layout> > } > static_assert(test_tuple_reversed<std::layout_left>()); // { dg-error > "expansion of" } > static_assert(test_tuple_reversed<std::layout_right>()); // { dg-error > "expansion of" } > +static_assert(test_tuple_reversed<std::layout_stride>()); // { dg-error > "expansion of" } > > template<typename Layout> > constexpr bool > @@ -65,6 +69,7 @@ template<typename Layout> > } > static_assert(test_tuple_over<std::layout_left>()); // { dg-error > "expansion of" } > static_assert(test_tuple_over<std::layout_right>()); // { dg-error > "expansion of" } > +static_assert(test_tuple_over<std::layout_stride>()); // { dg-error > "expansion of" } > > template<typename Layout> > constexpr bool > @@ -75,6 +80,7 @@ template<typename Layout> > } > static_assert(test_strided_slice_zero<std::layout_left>()); // { dg-error > "expansion of" } > static_assert(test_strided_slice_zero<std::layout_right>()); // { dg-error > "expansion of" } > +static_assert(test_strided_slice_zero<std::layout_stride>()); // { dg-error > "expansion of" } > > template<typename Layout> > constexpr bool > @@ -85,6 +91,7 @@ template<typename Layout> > } > static_assert(test_strided_slice_offset_under<std::layout_left>()); // { > dg-error "expansion of" } > static_assert(test_strided_slice_offset_under<std::layout_right>()); // { > dg-error "expansion of" } > +static_assert(test_strided_slice_offset_under<std::layout_stride>()); // { > dg-error "expansion of" } > > template<typename Layout> > constexpr bool > @@ -95,6 +102,7 @@ template<typename Layout> > } > static_assert(test_strided_slice_offset_over<std::layout_left>()); // { > dg-error "expansion of" } > static_assert(test_strided_slice_offset_over<std::layout_right>()); // { > dg-error "expansion of" } > +static_assert(test_strided_slice_offset_over<std::layout_stride>()); // { > dg-error "expansion of" } > > template<typename Layout> > constexpr bool > @@ -105,6 +113,7 @@ template<typename Layout> > } > static_assert(test_strided_slice_extent_over<std::layout_left>()); // { > dg-error "expansion of" } > static_assert(test_strided_slice_extent_over<std::layout_right>()); // { > dg-error "expansion of" } > +static_assert(test_strided_slice_extent_over<std::layout_stride>()); // { > dg-error "expansion of" } > > // { dg-prune-output "static assertion failed" } > // { dg-prune-output "__glibcxx_assert_fail" } > -- > 2.52.0 >
