On Mon, 26 May 2025 at 08:49, Tomasz Kaminski <tkami...@redhat.com> wrote:
>
>
>
> On Sat, May 24, 2025 at 1:29 PM Luc Grosheintz <luc.groshei...@gmail.com>
> wrote:
>>
>> The array that stores the dynamic extents used to be default
>> initialized. The standard requires value intialization. This
>> commit fixes the bug and adds a test.
>>
>> libstdc++-v3/ChangeLog:
>>
>> * include/std/mdspan: Value initialize the array storing the
>> dynamic extents.
>> * testsuite/23_containers/mdspan/extents/ctor_default.cc: New
>> test.
>>
>> Signed-off-by: Luc Grosheintz <luc.groshei...@gmail.com>
>> ---
>
> LGTM, thanks for noticing and fixing it.
> We also need approval from the maintainer.
OK for trunk.
>>
>> libstdc++-v3/include/std/mdspan | 2 +-
>> .../mdspan/extents/ctor_default.cc | 41 +++++++++++++++++++
>> 2 files changed, 42 insertions(+), 1 deletion(-)
>> create mode 100644
>> libstdc++-v3/testsuite/23_containers/mdspan/extents/ctor_default.cc
>>
>> diff --git a/libstdc++-v3/include/std/mdspan
>> b/libstdc++-v3/include/std/mdspan
>> index 47cfa405e44..bcf2fa60fea 100644
>> --- a/libstdc++-v3/include/std/mdspan
>> +++ b/libstdc++-v3/include/std/mdspan
>> @@ -146,7 +146,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>>
>> private:
>> using _S_storage = __array_traits<_IndexType,
>> _S_rank_dynamic>::_Type;
>> - [[no_unique_address]] _S_storage _M_dynamic_extents;
>> + [[no_unique_address]] _S_storage _M_dynamic_extents{};
>
> We know that these are integral types, so we can use {}.
>>
>> };
>>
>> template<typename _OIndexType, typename _SIndexType>
>> diff --git
>> a/libstdc++-v3/testsuite/23_containers/mdspan/extents/ctor_default.cc
>> b/libstdc++-v3/testsuite/23_containers/mdspan/extents/ctor_default.cc
>> new file mode 100644
>> index 00000000000..eec300f6896
>> --- /dev/null
>> +++ b/libstdc++-v3/testsuite/23_containers/mdspan/extents/ctor_default.cc
>> @@ -0,0 +1,41 @@
>> +// { dg-do run { target c++23 } }
>> +#include <mdspan>
>> +
>> +#include <cstdint>
>> +#include <testsuite_hooks.h>
>> +
>> +constexpr auto dyn = std::dynamic_extent;
>> +
>> +template<typename Extents>
>> + constexpr void
>> + test_default_ctor()
>> + {
>> + Extents exts;
>> + for(size_t i = 0; i < Extents::rank(); ++i)
>> + if(exts.static_extent(i) == std::dynamic_extent)
>> + VERIFY(exts.extent(i) == 0);
>> + else
>> + VERIFY(exts.extent(i) == Extents::static_extent(i));
>> + }
>> +
>> +constexpr bool
>> +test_default_ctor_all()
>> +{
>> + test_default_ctor<std::extents<int, 1>>();
>> + test_default_ctor<std::extents<int, dyn>>();
>> + test_default_ctor<std::extents<int, 1, 2>>();
>> + test_default_ctor<std::extents<int, dyn, 2>>();
>> + test_default_ctor<std::extents<int, dyn, dyn>>();
>> + test_default_ctor<std::extents<int, 1, 2, 3>>();
>> + test_default_ctor<std::extents<int, dyn, 2, dyn>>();
>> + test_default_ctor<std::extents<int, dyn, dyn, dyn>>();
>> + return true;
>> +}
>> +
>> +int
>> +main()
>> +{
>> + test_default_ctor_all();
>> + static_assert(test_default_ctor_all());
>> + return 0;
>> +}
>> --
>> 2.49.0
>>
