Hi,
I was just working on these things, too. So great, one thing less on
my list.

Patch looks fine, but for the parts with the prefix, which I find
suspicious, anyhow, too much black magic for me.

What is still missing then, is to add PRIxYYY macros. With the latest
draft

        https://open-std.org/JTC1/SC22/WG14/www/docs/n3096.pdf

these become mandatory feature tests for this feature. I already have
a patch for that.

I also have already patches for

- the wN and wfN length modifiers

- an extension towards `[u]int128_t`

- adding the `*_WIDTH` macros

And I will soon be starting on the similar features for `scanf` and
friends. There is one problem zone for that, namely that `0b` prefixes
are not only extensions but change semantics of existing executables
that would be linked against different versions of the C library.

My plan is to make the distinction deep down in `__intscan` and have
that internal function in two versions `__intscan_c17` and
`__intscan_c23`, say.

Thanks
Jₑₙₛ

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