[PATCH v5 3/8] libstdc++: Add tests for layout_left.
Luc Grosheintz
luc.grosheintz@gmail.com
Tue Jun 3 12:50:39 GMT 2025
On 6/3/25 14:31, Tomasz Kaminski wrote:
> On Mon, Jun 2, 2025 at 9:07 AM Luc Grosheintz <luc.grosheintz@gmail.com>
> wrote:
>
>>
>>
>> On 5/30/25 18:42, Luc Grosheintz wrote:
>>> Implements a suite of tests for the currently implemented parts of
>>> layout_left. The individual tests are templated over the layout type, to
>>> allow reuse as more layouts are added.
>>>
>>> libstdc++-v3/ChangeLog:
>>>
>>> * testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc: New
>> test.
>>> * testsuite/23_containers/mdspan/layouts/ctors.cc: New test.
>>> * testsuite/23_containers/mdspan/layouts/empty.cc: New test.
>>> * testsuite/23_containers/mdspan/layouts/mapping.cc: New test.
>>>
>>
>> CI complains that empty.cc contains a bug on 32-bit systems. I'll explain
>> below.
>>
>>> Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>
>>> ---
>>> .../mdspan/layouts/class_mandate_neg.cc | 36 ++
>>> .../23_containers/mdspan/layouts/ctors.cc | 280 +++++++++++
>>> .../23_containers/mdspan/layouts/empty.cc | 67 +++
>>> .../23_containers/mdspan/layouts/mapping.cc | 437 ++++++++++++++++++
>>> 4 files changed, 820 insertions(+)
>>> create mode 100644
>> libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
>>> create mode 100644
>> libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
>>> create mode 100644
>> libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
>>> create mode 100644
>> libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
>>>
>>> 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
>>> new file mode 100644
>>> index 00000000000..62526140200
>>> --- /dev/null
>>> +++
>> b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/class_mandate_neg.cc
>>> @@ -0,0 +1,36 @@
>>> +// { dg-do compile { target c++23 } }
>>> +#include<mdspan>
>>> +
>>> +#include <cstdint>
>>> +
>>> +constexpr size_t dyn = std::dynamic_extent;
>>> +static constexpr size_t n = std::numeric_limits<uint8_t>::max() / 2;
>>> +
>>> +template<typename Layout>
>>> + struct A
>>> + {
>>> + typename Layout::mapping<std::extents<uint8_t, n, 2>> m0;
>>> + typename Layout::mapping<std::extents<uint8_t, n, 2, dyn>> m1;
>>> + typename Layout::mapping<std::extents<uint8_t, n, 2, 0>> m2;
>>> +
>>> + using extents_type = std::extents<uint8_t, n, 4>;
>>> + typename Layout::mapping<extents_type> m3; // { dg-error "required
>> from" }
>>> + };
>>> +
>>> +template<size_t Count, typename Layout, typename OLayout>
>>> + struct B // { dg-error "expansion of" }
>>> + {
>>> + using Extents = std::extents<uint8_t, dyn, dyn, Count>;
>>> + using OExtents = std::extents<uint16_t, n, 4, Count>;
>>> +
>>> + using Mapping = typename Layout::mapping<Extents>;
>>> + using OMapping = typename OLayout::mapping<OExtents>;
>>> +
>>> + Mapping m{OMapping{}};
>>> + };
>>> +
>>> +A<std::layout_left> a_left; // { dg-error
>> "required from" }
>>> +
>>> +B<1, std::layout_left, std::layout_left> bll; // { dg-error
>> "required here" }
>>> +
>>> +// { dg-prune-output "must be representable as index_type" }
>>> diff --git
>> a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
>> b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
>>> new file mode 100644
>>> index 00000000000..8e1fd2d9524
>>> --- /dev/null
>>> +++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/ctors.cc
>>> @@ -0,0 +1,280 @@
>>> +// { dg-do run { target c++23 } }
>>> +#include <mdspan>
>>> +
>>> +#include <cstdint>
>>> +#include <testsuite_hooks.h>
>>> +
>>> +constexpr size_t dyn = std::dynamic_extent;
>>> +
>>> +template<typename Mapping, typename IndexType, size_t... Extents>
>>> + constexpr void
>>> + verify(std::extents<IndexType, Extents...> oexts)
>>> + {
>>> + auto m = Mapping(oexts);
>>> + VERIFY(m.extents() == oexts);
>>> + }
>>> +
>>> +template<typename Mapping, typename OMapping>
>>> + requires (requires { typename OMapping::layout_type; })
>>> + constexpr void
>>> + verify(OMapping other)
>>> + {
>>> + constexpr auto rank = Mapping::extents_type::rank();
>>> + auto m = Mapping(other);
>>> + VERIFY(m.extents() == other.extents());
>>> + if constexpr (rank > 0)
>>> + for(size_t i = 0; i < rank; ++i)
>>> + VERIFY(std::cmp_equal(m.stride(i), other.stride(i)));
>>> + }
>>> +
>>> +
>>> +template<typename To, typename From>
>>> + constexpr void
>>> + verify_convertible(From from)
>>> + {
>>> + static_assert(std::is_convertible_v<From, To>);
>>> + verify<To>(from);
>>> + }
>>> +
>>> +template<typename To, typename From>
>>> + constexpr void
>>> + verify_nothrow_convertible(From from)
>>> + {
>>> + static_assert(std::is_nothrow_constructible_v<To, From>);
>>> + verify_convertible<To>(from);
>>> + }
>>> +
>>> +template<typename To, typename From>
>>> + constexpr void
>>> + verify_constructible(From from)
>>> + {
>>> + static_assert(!std::is_convertible_v<From, To>);
>>> + static_assert(std::is_constructible_v<To, From>);
>>> + verify<To>(from);
>>> + }
>>> +
>>> +template<typename To, typename From>
>>> + constexpr void
>>> + verify_nothrow_constructible(From from)
>>> + {
>>> + static_assert(std::is_nothrow_constructible_v<To, From>);
>>> + verify_constructible<To>(from);
>>> + }
>>> +
>>> +template<typename Mapping, typename OExtents>
>>> + constexpr void
>>> + assert_not_constructible()
>>> + {
>>> + static_assert(!std::is_constructible_v<Mapping, OExtents>);
>>> + }
>>> +
>>> +// ctor: mapping()
>>> +namespace default_ctor
>>> +{
>>> + template<typename Layout, typename Extents>
>>> + constexpr void
>>> + test_default_ctor()
>>> + {
>>> + using Mapping = typename Layout::mapping<Extents>;
>>> +
>>> + Mapping m;
>>> + for(size_t i = 0; i < Extents::rank(); ++i)
>>> + {
>>> + if (Extents::static_extent(i) == std::dynamic_extent)
>>> + VERIFY(m.extents().extent(i) == 0);
>>> + else
>>> + VERIFY(m.extents().static_extent(i) ==
>> Extents::static_extent(i));
>>> + }
>>> + }
>>> +
>>> + template<typename Layout>
>>> + constexpr bool
>>> + test_default_ctor_all()
>>> + {
>>> + test_default_ctor<Layout, std::extents<int, dyn>>();
>>> + test_default_ctor<Layout, std::extents<int, 1, 2>>();
>>> + test_default_ctor<Layout, std::extents<int, dyn, 2>>();
>>> + test_default_ctor<Layout, std::extents<int, dyn, dyn>>();
>>> + test_default_ctor<Layout, std::extents<int, dyn, 2, dyn>>();
>>> + test_default_ctor<Layout, std::extents<int, dyn, dyn, dyn>>();
>>> + return true;
>>> + }
>>> +
>>> + template<typename Layout>
>>> + constexpr void
>>> + test_all()
>>> + {
>>> + test_default_ctor_all<Layout>();
>>> + static_assert(test_default_ctor_all<Layout>());
>>> + }
>>> +}
>>> +
>>> +// ctor: mapping(const extents&)
>>> +namespace from_extents
>>> +{
>>> + template<typename Layout, typename Extents, typename OExtents>
>>> + constexpr void
>>> + verify_nothrow_convertible(OExtents oexts)
>>> + {
>>> + using Mapping = typename Layout::mapping<Extents>;
>>> + ::verify_nothrow_convertible<Mapping>(oexts);
>>> + }
>>> +
>>> + template<typename Layout, typename Extents, typename OExtents>
>>> + constexpr void
>>> + verify_nothrow_constructible(OExtents oexts)
>>> + {
>>> + using Mapping = typename Layout::mapping<Extents>;
>>> + ::verify_nothrow_constructible<Mapping>(oexts);
>>> + }
>>> +
>>> + template<typename Layout, typename Extents, typename OExtents>
>>> + constexpr void
>>> + assert_not_constructible()
>>> + {
>>> + using Mapping = typename Layout::mapping<Extents>;
>>> + ::assert_not_constructible<Mapping, OExtents>();
>>> + }
>>> +
>>> + template<typename Layout>
>>> + constexpr bool
>>> + test_ctor()
>>> + {
>>> + verify_nothrow_convertible<Layout, std::extents<int>>(
>>> + std::extents<int>{});
>>> +
>>> + verify_nothrow_convertible<Layout, std::extents<int, 2>>(
>>> + std::extents<int, 2>{});
>>> +
>>> + verify_nothrow_convertible<Layout, std::extents<int, dyn, 3>>(
>>> + std::extents<int, dyn, 3>{2});
>>> +
>>> + verify_nothrow_constructible<Layout, std::extents<unsigned int>>(
>>> + std::extents<int>{});
>>> +
>>> + verify_nothrow_constructible<Layout, std::extents<int, dyn>>(
>>> + std::extents<int, 2>{});
>>> +
>>> + verify_nothrow_constructible<Layout, std::extents<int, dyn, 3>>(
>>> + std::extents<int, 2, 3>{});
>>> +
>>> + assert_not_constructible<Layout, std::extents<int>,
>>> + std::extents<unsigned int>>();
>>> + assert_not_constructible<Layout, std::extents<int, 2>,
>>> + std::extents<int, dyn>>();
>>> + assert_not_constructible<Layout, std::extents<int, 2, 3>,
>>> + std::extents<int, dyn, 3>>();
>>> + return true;
>>> + }
>>> +
>>> + template<typename Layout, typename Extents>
>>> + constexpr void
>>> + assert_deducible(Extents exts)
>>> + {
>>> + typename Layout::mapping m(exts);
>>> + static_assert(std::same_as<decltype(m),
>>> + typename Layout::mapping<Extents>>);
>>> + }
>>> +
>>> + template<typename Layout>
>>> + constexpr void
>>> + test_deducible()
>>> + {
>>> + assert_deducible<Layout>(std::extents<int>());
>>> + assert_deducible<Layout>(std::extents<int, 1>());
>>> + assert_deducible<Layout>(std::extents<int, 1, 2, dyn>(3));
>>> + }
>>> +
>>> + template<typename Layout>
>>> + constexpr void
>>> + test_all()
>>> + {
>>> + test_ctor<Layout>();
>>> + static_assert(test_ctor<Layout>());
>>> + test_deducible<Layout>();
>>> + }
>>> +}
>>> +
>>> +// ctor: mapping(mapping<OExtents>)
>>> +namespace from_same_layout
>>> +{
>>> + template<typename Layout, typename Extents, typename OExtents>
>>> + constexpr void
>>> + verify_nothrow_convertible(OExtents exts)
>>> + {
>>> + using Mapping = typename Layout::mapping<Extents>;
>>> + using OMapping = typename Layout::mapping<OExtents>;
>>> +
>>> + ::verify_nothrow_convertible<Mapping>(OMapping(exts));
>>> + }
>>> +
>>> + template<typename Layout, typename Extents, typename OExtents>
>>> + constexpr void
>>> + verify_nothrow_constructible(OExtents exts)
>>> + {
>>> + using Mapping = typename Layout::mapping<Extents>;
>>> + using OMapping = typename Layout::mapping<OExtents>;
>>> +
>>> + ::verify_nothrow_constructible<Mapping>(OMapping(exts));
>>> + }
>>> +
>>> + template<typename Layout>
>>> + constexpr bool
>>> + test_ctor()
>>> + {
>>> + verify_nothrow_convertible<Layout, std::extents<unsigned int>>(
>>> + std::extents<int>{});
>>> +
>>> + verify_nothrow_constructible<Layout, std::extents<int>>(
>>> + std::extents<unsigned int>{});
>>> +
>>> + assert_not_constructible<
>>> + typename Layout::mapping<std::extents<int>>,
>>> + typename Layout::mapping<std::extents<int, 1>>>();
>>> +
>>> + assert_not_constructible<
>>> + 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});
>>> +
>>> + verify_nothrow_convertible<Layout, std::extents<int, dyn>>(
>>> + std::extents<int, 1>{});
>>> +
>>> + assert_not_constructible<
>>> + typename Layout::mapping<std::extents<int, 1, 2>>,
>>> + typename Layout::mapping<std::extents<int, 1>>>();
>>> +
>>> + 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>{});
>>> + return true;
>>> + }
>>> +
>>> + template<typename Layout>
>>> + constexpr void
>>> + test_all()
>>> + {
>>> + test_ctor<Layout>();
>>> + static_assert(test_ctor<Layout>());
>>> + }
>>> +}
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_all()
>>> + {
>>> + default_ctor::test_all<Layout>();
>>> + from_extents::test_all<Layout>();
>>> + from_same_layout::test_all<Layout>();
>>> + }
>>> +
>>> +int
>>> +main()
>>> +{
>>> + test_all<std::layout_left>();
>>> + return 0;
>>> +}
>>> diff --git
>> a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
>> b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
>>> new file mode 100644
>>> index 00000000000..10843e2a2bb
>>> --- /dev/null
>>> +++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/empty.cc
>>> @@ -0,0 +1,67 @@
>>> +// { dg-do run { target c++23 } }
>>> +#include <mdspan>
>>> +
>>> +#include <cstdint>
>>> +#include <testsuite_hooks.h>
>>> +
>>> +constexpr size_t dyn = std::dynamic_extent;
>>> +
>>> +template<typename Mapping>
>>> + constexpr void
>>> + invoke_stride(Mapping m)
>>> + {
>>> + // Only checking for UB, e.g. signed overflow.
>>> + for(size_t i = 0; i < Mapping::extents_type::rank(); ++i)
>>> + m.stride(i);
>>> + }
>>> +
>>> +template<typename Mapping>
>>> + constexpr void
>>> + verify_required_span_size(Mapping m)
>>> + { VERIFY(m.required_span_size() == 0); }
>>> +
>>> +template<typename Mapping>
>>> + constexpr void
>>> + verify_all(Mapping m)
>>> + {
>>> + verify_required_span_size(m);
>>> + invoke_stride(m);
>>> + }
>>> +
>>> +template<typename Layout, typename Int>
>>> +constexpr void
>>> +test_default_constructed()
>>> +{
>>> + constexpr auto n = std::numeric_limits<Int>::max();
>>> + 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>>{});
>>> + verify_all(typename Layout::mapping<std::extents<Int, dyn, n, n,
>> n>>{});
>>> + verify_all(typename Layout::mapping<std::extents<Int, n, n, n, 0>>{});
>>> + verify_all(typename Layout::mapping<std::extents<Int, n, n, n,
>> dyn>>{});
>>> +}
>>
>> The problem here are cases where
>>
>> sizeof(Int) >= sizeof(size_t)
>>
>> and it comes in two variations:
>>
>> 1. 32-bit systems: failure due to narrowing conversion from `long long
>> int` to size_t, which is the bug that the CI found.
>>
>
>> 2. any system: If `sizeof(Int) == sizeof(size_t) && is_unsigned_v<Int>`
>> then `n == std::dynamic_extents` and the test is ineffective.
>>
>> Proposed solution:
>>
>> constexpr Int n1 = std::numeric_limits<Int>::max();
>> constexpr size_t n2 = std::numeric_limits<size_t>::max() - 1;
>> constexpr size_t n = std::cmp_less(n1, n2) ? size_t(n1) : n2;
>>
> And I would replace: std::numeric_limits<size_t>::max() - 1 with
> dynamic_extent-1.
> This would make it more clear for the reader. You can also add a
> constructor.
>>
>>
>> -------------------------------------------------------------------------
>>
>> The tests are also insufficient because they don't cover cases where
>> the overflow could happen while multiplying dynamic extents.
>>
> In which code path that multiplication will happen? I think it will always
> trigger
> the preconditions in the constructor.
>
Look at the extents, they're all either:
* fully static with a 0,
* or have one dyn which is 0.
What we don't check is the case where we have 4 dynamic extents,
one is 0 and the rest are huge, e.g.
layout_left::mapping(std::dextents<Int, 4>(n, n, n, 0));
This matters because we split __exts_prod as follow:
__exts_prod = __sta_prod * __dyn_prod
(The notation isn't very precise, but is gets to the core.)
We've carefully checked that there's no overflow in computing
__sta_prod but not __dyn_prod.
The way this could cause issues is via m.stride(i) (for layout_left
and layout_right) or maybe in `required_span_size()` (if one doesn't
prescan for 0).
Remember the cases in empty.cc don't trigger the precondition, because
the required span size is 0.
>>
>>> +
>>> +template<typename Layout>
>>> +constexpr bool
>>> +test_all()
>>> +{
>>> + test_default_constructed<Layout, signed char>();
>>> + test_default_constructed<Layout, short int>();
>>> + test_default_constructed<Layout, int>();
>>> + test_default_constructed<Layout, long int>();
>>> + test_default_constructed<Layout, long long int>();
>>> +
>>> + test_default_constructed<Layout, unsigned char>();
>>> + test_default_constructed<Layout, unsigned short int>();
>>> + test_default_constructed<Layout, unsigned int>();
>>> + test_default_constructed<Layout, unsigned long int>();
>>> + test_default_constructed<Layout, unsigned long long int>();
>>> + test_default_constructed<Layout, size_t>();
>>> + return true;
>>> +}
>>> +
>>> +int
>>> +main()
>>> +{
>>> + static_assert(test_all<std::layout_left>());
>>> + return 0;
>>> +}
>>> diff --git
>> a/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
>> b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
>>> new file mode 100644
>>> index 00000000000..a5be1166617
>>> --- /dev/null
>>> +++ b/libstdc++-v3/testsuite/23_containers/mdspan/layouts/mapping.cc
>>> @@ -0,0 +1,437 @@
>>> +// { dg-do run { target c++23 } }
>>> +#include <mdspan>
>>> +
>>> +#include <cstdint>
>>> +#include <testsuite_hooks.h>
>>> +
>>> +constexpr size_t dyn = std::dynamic_extent;
>>> +
>>> +template<typename Layout, typename Extents>
>>> + constexpr bool
>>> + test_mapping_properties()
>>> + {
>>> + using M = typename Layout::mapping<Extents>;
>>> + static_assert(std::__mdspan::__is_extents<typename
>> M::extents_type>);
>>> + static_assert(std::copyable<M>);
>>> + static_assert(std::is_nothrow_move_constructible_v<M>);
>>> + static_assert(std::is_nothrow_move_assignable_v<M>);
>>> + static_assert(std::is_nothrow_swappable_v<M>);
>>> + static_assert(std::is_same_v<typename M::extents_type, Extents>);
>>> + static_assert(std::is_same_v<typename M::index_type,
>>> + typename M::extents_type::index_type>);
>>> + static_assert(std::is_same_v<typename M::size_type,
>>> + typename M::extents_type::size_type>);
>>> + static_assert(std::is_same_v<typename M::rank_type,
>>> + typename M::extents_type::rank_type>);
>>> + static_assert(std::is_same_v<typename M::layout_type, Layout>);
>>> +
>>> + static_assert(std::is_trivially_copyable_v<M>);
>>> + static_assert(std::regular<M>);
>>> +
>>> + static_assert(M::is_always_unique() && M::is_unique());
>>> + static_assert(M::is_always_strided() && M::is_strided());
>>> + return true;
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr bool
>>> + test_mapping_properties_all()
>>> + {
>>> + test_mapping_properties<Layout, std::extents<int>>();
>>> + test_mapping_properties<Layout, std::extents<int, 1>>();
>>> + test_mapping_properties<Layout, std::extents<int, dyn>>();
>>> + test_mapping_properties<Layout, std::extents<int, dyn, dyn>>();
>>> + return true;
>>> + }
>>> +
>>> +// Check operator()(Indices...)
>>> +template<typename Mapping, size_t N>
>>> + constexpr typename Mapping::index_type
>>> + linear_index(const Mapping& mapping,
>>> + const std::array<typename Mapping::index_type, N>& indices)
>>> + {
>>> + typename Mapping::index_type ret = 0;
>>> + for(size_t r = 0; r < indices.size(); ++r)
>>> + ret += indices[r] * mapping.stride(r);
>>> + return ret;
>>> + }
>>> +
>>> +template<typename Mapping, typename... Indices>
>>> + constexpr void
>>> + test_linear_index(const Mapping& m, Indices... i)
>>> + {
>>> + using index_type = typename Mapping::index_type;
>>> + index_type expected = linear_index(m, std::array{index_type(i)...});
>>> + VERIFY(m(i...) == expected);
>>> + VERIFY(m(uint8_t(i)...) == expected);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_linear_index_0d()
>>> + {
>>> + constexpr typename Layout::mapping<std::extents<int>> m;
>>> + VERIFY(m() == 0);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_linear_index_1d()
>>> + {
>>> + typename Layout::mapping<std::extents<int, 5>> m;
>>> + test_linear_index(m, 0);
>>> + test_linear_index(m, 1);
>>> + test_linear_index(m, 4);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_linear_index_2d()
>>> + {
>>> + typename Layout::mapping<std::extents<int, 3, 256>> m;
>>> + test_linear_index(m, 0, 0);
>>> + test_linear_index(m, 1, 0);
>>> + test_linear_index(m, 0, 1);
>>> + test_linear_index(m, 1, 1);
>>> + test_linear_index(m, 2, 4);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + struct MappingFactory
>>> + {
>>> + template<typename Extents>
>>> + static constexpr typename Layout::mapping<Extents>
>>> + create(Extents exts)
>>> + { return exts; }
>>> + };
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_linear_index_3d()
>>> + {
>>> + auto m = MappingFactory<Layout>::create(std::extents(3, 5, 7));
>>> + test_linear_index(m, 0, 0, 0);
>>> + test_linear_index(m, 1, 0, 0);
>>> + test_linear_index(m, 0, 1, 0);
>>> + test_linear_index(m, 0, 0, 1);
>>> + test_linear_index(m, 1, 1, 0);
>>> + test_linear_index(m, 2, 4, 6);
>>> + }
>>> +
>>> +struct IntLikeA
>>> +{
>>> + operator int()
>>> + { return 0; }
>>> +};
>>> +
>>> +struct IntLikeB
>>> +{
>>> + operator int() noexcept
>>> + { return 0; }
>>> +};
>>> +
>>> +struct NotIntLike
>>> +{ };
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_has_linear_index_0d()
>>> + {
>>> + using Mapping = typename Layout::mapping<std::extents<int>>;
>>> + static_assert(std::invocable<Mapping>);
>>> + static_assert(!std::invocable<Mapping, int>);
>>> + static_assert(!std::invocable<Mapping, IntLikeA>);
>>> + static_assert(!std::invocable<Mapping, IntLikeB>);
>>> + static_assert(!std::invocable<Mapping, NotIntLike>);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_has_linear_index_1d()
>>> + {
>>> + using Mapping = typename Layout::mapping<std::extents<int, 3>>;
>>> + static_assert(std::invocable<Mapping, int>);
>>> + static_assert(!std::invocable<Mapping>);
>>> + static_assert(!std::invocable<Mapping, IntLikeA>);
>>> + static_assert(std::invocable<Mapping, IntLikeB>);
>>> + static_assert(!std::invocable<Mapping, NotIntLike>);
>>> + static_assert(std::invocable<Mapping, double>);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_has_linear_index_2d()
>>> + {
>>> + using Mapping = typename Layout::mapping<std::extents<int, 3, 5>>;
>>> + static_assert(std::invocable<Mapping, int, int>);
>>> + static_assert(!std::invocable<Mapping, int>);
>>> + static_assert(!std::invocable<Mapping, IntLikeA, int>);
>>> + static_assert(std::invocable<Mapping, IntLikeB, int>);
>>> + static_assert(!std::invocable<Mapping, NotIntLike, int>);
>>> + static_assert(std::invocable<Mapping, double, double>);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr bool
>>> + test_linear_index_all()
>>> + {
>>> + test_linear_index_0d<Layout>();
>>> + test_linear_index_1d<Layout>();
>>> + test_linear_index_2d<Layout>();
>>> + test_linear_index_3d<Layout>();
>>> + test_has_linear_index_0d<Layout>();
>>> + test_has_linear_index_1d<Layout>();
>>> + test_has_linear_index_2d<Layout>();
>>> + return true;
>>> + }
>>> +
>>> +template<typename Mapping>
>>> + constexpr typename Mapping::index_type
>>> + linear_index_end(Mapping m)
>>> + {
>>> + using index_type = typename Mapping::index_type;
>>> + constexpr size_t rank = Mapping::extents_type::rank();
>>> +
>>> + auto impl = [m]<index_type... Counts>(
>>> + std::integer_sequence<index_type, Counts...>) -> index_type
>>> + {
>>> + auto exts = m.extents();
>>> + if(((exts.extent(Counts) == 0) || ...))
>>> + return 0;
>>> + return m((exts.extent(Counts) - 1)...) + 1;
>>> + };
>>> +
>>> + return impl(std::make_integer_sequence<index_type, rank>());
>>> + }
>>> +
>>> +// Check required_span_size
>>> +template<typename Mapping>
>>> + constexpr void
>>> + test_required_span_size(Mapping m)
>>> + { VERIFY(m.required_span_size() == linear_index_end(m)); }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_required_span_size_0d()
>>> + {
>>> + typename Layout::mapping<std::extents<int>> m;
>>> + test_required_span_size(m);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_required_span_size_1d()
>>> + {
>>> + auto m = MappingFactory<Layout>::create(std::extents(3));
>>> + test_required_span_size(m);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_required_span_size_2d()
>>> + {
>>> + auto m = MappingFactory<Layout>::create(std::extents(3, 5));
>>> + test_required_span_size(m);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_required_span_size_3d()
>>> + {
>>> + auto m = MappingFactory<Layout>::create(std::extents(3, 5, 7));
>>> + test_required_span_size(m);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_required_span_size_zero_1d()
>>> + {
>>> + auto m = MappingFactory<Layout>::create(std::extents(3, 0));
>>> + test_required_span_size(m);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_required_span_size_zero_3d()
>>> + {
>>> + auto m = MappingFactory<Layout>::create(std::extents(3, 0, 7));
>>> + test_required_span_size(m);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr bool
>>> + test_required_span_size_all()
>>> + {
>>> + test_required_span_size_0d<Layout>();
>>> + test_required_span_size_1d<Layout>();
>>> + test_required_span_size_2d<Layout>();
>>> + test_required_span_size_3d<Layout>();
>>> + test_required_span_size_zero_1d<Layout>();
>>> + test_required_span_size_zero_3d<Layout>();
>>> + return true;
>>> + }
>>> +
>>> +// Check stride
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_stride_1d()
>>> + {
>>> + std::layout_left::mapping<std::extents<int, 3>> m;
>>> + VERIFY(m.stride(0) == 1);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_stride_2d();
>>> +
>>> +template<>
>>> + constexpr void
>>> + test_stride_2d<std::layout_left>()
>>> + {
>>> + std::layout_left::mapping<std::extents<int, 3, 5>> m;
>>> + VERIFY(m.stride(0) == 1);
>>> + VERIFY(m.stride(1) == 3);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_stride_3d();
>>> +
>>> +template<>
>>> + constexpr void
>>> + test_stride_3d<std::layout_left>()
>>> + {
>>> + std::layout_left::mapping m(std::dextents<int, 3>(3, 5, 7));
>>> + VERIFY(m.stride(0) == 1);
>>> + VERIFY(m.stride(1) == 3);
>>> + VERIFY(m.stride(2) == 3*5);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr bool
>>> + test_stride_all()
>>> + {
>>> + test_stride_1d<Layout>();
>>> + test_stride_2d<Layout>();
>>> + test_stride_3d<Layout>();
>>> + return true;
>>> + }
>>> +
>>> +template<typename Mapping>
>>> + concept has_stride = requires (Mapping m)
>>> + {
>>> + { m.stride(0) } -> std::same_as<typename Mapping::index_type>;
>>> + };
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_has_stride_0d()
>>> + {
>>> + using Mapping = typename Layout::mapping<std::extents<int>>;
>>> + constexpr bool expected = false;
>>> + static_assert(has_stride<Mapping> == expected);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_has_stride_1d()
>>> + { static_assert(has_stride<typename Layout::mapping<std::extents<int,
>> 1>>>); }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_has_stride_2d()
>>> + {
>>> + using Extents = std::extents<int, 1, 2>;
>>> + static_assert(has_stride<typename Layout::mapping<Extents>>);
>>> + }
>>> +
>>> +// Check operator==
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_eq()
>>> + {
>>> + typename Layout::mapping<std::extents<int, 1, 2>> m1;
>>> + typename Layout::mapping<std::extents<int, 2, 2>> m2;
>>> + typename Layout::mapping<std::dextents<int, 2>> m3(m1);
>>> +
>>> + VERIFY(m1 == m1);
>>> + VERIFY(m1 != m2);
>>> + VERIFY(m1 == m3);
>>> + VERIFY(m2 != m3);
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_eq_zero()
>>> + {
>>> + typename Layout::mapping<std::extents<int, 0, 2>> m1;
>>> + typename Layout::mapping<std::extents<int, 0, 2>> m2;
>>> + typename Layout::mapping<std::extents<int, 2, 0>> m3;
>>> +
>>> + VERIFY(m1 == m2);
>>> + VERIFY(m1 != m3);
>>> + }
>>> +
>>> +template<typename M1, typename M2>
>>> + concept has_op_eq = requires (M1 m1, M2 m2)
>>> + {
>>> + { m1 == m2 } -> std::same_as<bool>;
>>> + { m2 == m1 } -> std::same_as<bool>;
>>> + { m1 != m2 } -> std::same_as<bool>;
>>> + { m2 != m1 } -> std::same_as<bool>;
>>> + };
>>> +
>>> +template<typename Layout>
>>> + constexpr bool
>>> + test_has_op_eq()
>>> + {
>>> + static_assert(!has_op_eq<
>>> + typename Layout::mapping<std::extents<int, 1, 2>>,
>>> + typename Layout::mapping<std::extents<int, 1>>>);
>>> +
>>> + static_assert(has_op_eq<
>>> + typename Layout::mapping<std::extents<int, 1>>,
>>> + typename Layout::mapping<std::extents<int, 1>>>);
>>> +
>>> + static_assert(has_op_eq<
>>> + typename Layout::mapping<std::extents<int, 1>>,
>>> + typename Layout::mapping<std::extents<int, 2>>>);
>>> + return true;
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr bool
>>> + test_mapping_all()
>>> + {
>>> + test_linear_index_all<Layout>();
>>> + test_required_span_size_all<Layout>();
>>> + test_stride_all<Layout>();
>>> +
>>> + test_eq<Layout>();
>>> + test_eq_zero<Layout>();
>>> + return true;
>>> + }
>>> +
>>> +template<typename Layout>
>>> + constexpr void
>>> + test_all()
>>> + {
>>> + static_assert(std::is_trivially_default_constructible_v<Layout>);
>>> + static_assert(std::is_trivially_copyable_v<Layout>);
>>> + static_assert(test_mapping_properties_all<Layout>());
>>> +
>>> + test_mapping_all<Layout>();
>>> + static_assert(test_mapping_all<Layout>());
>>> +
>>> + test_has_stride_0d<Layout>();
>>> + test_has_stride_1d<Layout>();
>>> + test_has_stride_2d<Layout>();
>>> + test_has_op_eq<Layout>();
>>> + }
>>> +
>>> +int
>>> +main()
>>> +{
>>> + test_all<std::layout_left>();
>>> + return 0;
>>> +}
>>
>>
>
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