On 4/22/21 11:16 AM, Corentin Jabot via SG16 wrote:
Hey Victor,
I hope you are doing well, thanks for your reply!
A few comments below.

On Thu, Apr 22, 2021 at 4:26 PM Victor Zverovich <victor.zverovich@gmail.com> wrote:
> Peter:
> What should the following code do?

I think (1) is the only acceptable option because all the rest are inconsistent with existing std::format overloads.

> “std::locale in its current form is pretty much useless,” may be a true statement but it doesn’t help me make progress.

Maybe we are trying to make "progress" in the wrong direction? We don't have to quickly hack something together for new std::format overloads. We didn't have a chance to look at locale in C++20 but now is a great time.

> Corentin:
> Converting between UTF-X and UTF-Y is a lossless operation.

Only valid ones. There is still a question of handling transcoding errors.

I think to make progress SG16 will need to resolve "what if a string pretends to be in encoding X but isn't".
In this case, what happens when a u8 string isn't a u8 string? (this is a rhetorical question, I don't expect SG16 will come to an agreement any time soon).
Only then can we make progress - P1880 had a point.

We had consensus on P1880 within SG16; at least for the direction.  We forwarded it to LEWG to resolve C++20 FR164.  I believe wording challenges, and the author choosing to no longer pursue it, are what has prevented progress.