> Not that I'm expecting Microsoft to ship full conformance for C++23 any time soon,

They are actively working on it for their VS2026 C++ compiler. I think since 2017 or so they've kept up with C++ standards reasonably? I'm not a heavy C++ guy, so maybe I'm wrong, but my understanding is they match the standards.

> I'm not normally keen to "well actually" people with the C standard, but .. if you're writing in assembly, you're not writing in C.

These days on Linux/BSD/Solaris/macOS you can use makecontext()/swapcontext() from ucontext.h and it will turn out roughly the same performance on important architectures as what everyone used to do with custom assembly. And you already have fiber functions as part of the Windows API to trampoline.

I had to support a number of architectures in libdex for Debian. This is GNOME code of course, which isn't everyone's cup of C. (It also supports BSDs/Linux/macOS/Solaris/Windows).

* https://packages.debian.org/sid/libdex-1-1

* https://gitlab.gnome.org/GNOME/libdex

Boost has stackful coroutines. They also used to be in posix (makecontext).

There is no "Linux/ARM[64]". But there are "Raspberry Pi" and "RISC-V". I don't know such OSes, to be honest :-)

This support table is complete mess. And saying "most platforms are supported" is too optimistic or even cocky.

Looking at the repo, it falls back to Windows fibers on Windows/ARM. If you'd like a coroutine with more backends, I'm a fan of libco: https://github.com/higan-emu/libco/ which has assembly backends for x86, amd64, ppc, ppc-64, arm, and arm64 (and falls back to setjmp on POSIX platforms and fibers on Windows). Obviously the real solution would be for the C or C++ committees to add stackful coroutines to the standard, but unless that happens I would rather give up support for hppa or alpha or 8-bit AVR or whatever than not be able to use stackful corountines.

I think what they meant is that that what it takes to add coroutines support to a C/++ program. Adding it to, say, Java or C# is much more involved.