On 7/14/25 08:57, Tomasz Kaminski wrote:
Hi Luc, While running the libc++ test on libstdc++ we have found the following issue in our implementation. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121061 Would you be interested in looking into fixing this?
Yes, I'll take care of this. Do you know if it's the only issue? If it's not clear it might make sense that I learn how to run their tests on our code.
Also, libc++ makes the default constructor of mdpsan conditionally noexcept as extension (standard does not require it https://eel.is/c++draft/views.multidim#mdspan.mdspan.cons). We could do the same. Instead of writing a big conditional noexcept specification, I would suggest defaultint the constructor on first declaration: constexpr mdspan() requires (rank_dynamic() > 0) && is_default_constructible_v<data_handle_type> && is_default_constructible_v<mapping_type> && is_default_constructible_v<accessor_type> = default; And then having default member initializers: private: [[no_unique_address]] accessor_type _M_accessor = accessor_type(); [[no_unique_address]] mapping_type _M_mapping = mapping_type(); [[no_unique_address]] data_handle_type _M_handle = data_handle_type(); We do not want to use "{}" as the samantis is a bit differnt.
Yes, I think it makes sense if those two implementations behave the same.
