Multi-threading support

Who stopped using pthreads/windows threads for this?

Unicode support

Those who care use icu anyway.

memccpy()

First of all, 😄.
Secondly, it's a library feature, not a language one.
Thirdly, it existed forever in POSIX.
And lastly, good bait 😄.

whats so bad about Various syntax changes improve compatibility with C++

It's bad because compiler implementations keep adding warnings and enabling them by default about completely valid usage that got "deprecated" or "removed" in "future versions of C" I will never use or give a fuck about. So my CI runs which all minimally have -Wall -Werror can fail with a compiler upgrade for absolutely irrelevant stuff to me. If it wasn't for that, I wouldn't even know about these changes' existence, because I have zero interest in them.

Those who like C++ should use C++ anyway. They can use the C+classes style if they like (spoiler alert: they already do).

I can understand. But why would you not use newer C versions, if there is no compatibility with older version “required”?

Because C doesn’t exist in a vacuum, and Rust exists. Other choices exist too for those who don't like Rust.

My C projects are mature and have been in production for a long time. They are mostly maintenance only, with new minor features added not so often, and only after careful consideration.

^Still^ ^interested^ ^in^ ^knowing^ ^what^ ^relevant^ ^projects^ ^will^ ^be^ ^using^ ^C23.^