[PATCH] Export std::dextents from std.cc.in [PR121174]

[Jonathan Wakely]

On Sat, 19 Jul 2025, 14:20 Jakub Jelinek, <jakub@redhat.com> wrote:

> Hi!
>
> r16-442 implemented both std::extents and std::dextents (and perhaps other
> stuff), but exported only std::extents.
> I went through https://eel.is/c++draft/mdspan.syn and I think
> std::dextents
> is the only one implemented but not exported.
>
> The following patch exports it, and additionally appends some further
> entities to the FIXME list, those all seems to be unimplemented yet.
>

Yes, those are all C++26 additions to the header and not supported yet.



> Tested on x86_64-linux, ok for trunk?
>

OK, thanks.



> 2025-07-19  Jakub Jelinek  <jakub@redhat.com>
>
>         PR libstdc++/121174
>         * src/c++23/std.cc.in (std::dextents): Export.  Add to FIXME
> comments
>         other not yet implemented nor exported <mdspan> entities.
>
> --- libstdc++-v3/src/c++23/std.cc.in.jj 2025-07-19 14:39:32.617034910 +0200
> +++ libstdc++-v3/src/c++23/std.cc.in    2025-07-19 14:41:32.641471785
> +0200
> @@ -1850,12 +1850,15 @@ export namespace std
>  export namespace std
>  {
>    using std::extents;
> +  using std::dextents;
>    using std::layout_left;
>    using std::layout_right;
>    using std::layout_stride;
>    using std::default_accessor;
>    using std::mdspan;
> -  // FIXME layout_left_padded, layout_right_padded, aligned_accessor,
> mdsubspan
> +  // FIXME layout_left_padded, layout_right_padded, aligned_accessor,
> +  // strided_slice, submdspan_mapping_result, full_extent_t, full_extent,
> +  // submdspan_extents, mdsubspan
>  }
>  #endif
>
>
>         Jakub
>
>
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