On Mon, Jun 10, 2024 at 9:31 PM Ivan Solovev via SG16 <sg16_at_[hidden]>
wrote:

> Hello,
>
> I'm one of the contributors to the Qt Project, and I'm now working on
> adding
> std::format support for Qt string types. I have some questions that I'd
> like
> to clarify with the SG16 group.
>
> Qt string types include:
> * QString and QStringView: owning container and non-owning view on UTF-16
> data
> * QUtf8StringView: non-owning view on UTF-8 data
> * QLatin1StringView: non-owning view on Latin1 data
>
> What I'm trying to do is to provide std::formatter<QT_STRING_TYPE, char>
> for each of the string types mentioned above.
> The tricky question here is - which encoding should be used for the
> generated char string?
>
> We are discussing it in the Qt Project mailing list (link to the
> discussion:
> https://lists.qt-project.org/pipermail/development/2024-June/045380.html),
> and we're currently leaning towards encoding everything in UTF-8.
> But before going forward, we wanted to check with SG16 to make sure that
> we do not end up with something that will cause compatibility issues in
> future.
>
> So, my questions are:
> * Are there any plans to support charN_t formatters in the standard?
> * How std::formatter<charN_t, char> would behave in this case?
>
> I've read
> https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2728r6.html#add-utf_view-specialization-of-formatter
> and it looks like UTF-8 is the right choice if it gets accepted.
> How probable is that? Are there any other papers related to this topic?
>
> I've seen https://lists.isocpp.org/sg16/2024/05/4305.php but the link to
> the draft of the paper in that email does not work for me.
>

https://wg21.link/P3258
I hope that answers some of your question

Cheers!


> I'd appreciate any comments about the current state and future plans of
> charN_t support in std::format.
>
> Thanks,
> Ivan
>
> ------------------------------
>
> Ivan Solovev
> Senior Software Engineer
>
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