> contains notes on compiling for IRIX, HPUX, AIX, and OSF/1.

Again, how well tested do you imagine the OSF/1 target is? Do you imagine each merge pops off a CI test for that platform? My guess is -- it's been a long time since anyone connected with the GNU coreutils project built for that platform.

See the reply from estebank to me, below:

> Platform support goes beyond "does a compiler happen to produce a binary".

Fair. I suppose it comes down to what "supported" means. AFAICT there's no official CI testing for any platform; the closest thing seems to be a mailing list where people will sometimes test new releases. It would be interesting to see what would happen if someone found and reported a bug for something obscure.

Okay, so I was curious enough to check... I can install NetBSD on an emulated VAX (opensimh), run

  pkgin install coreutils

and those binaries do in fact work. I can't seem to find documentation of whether they run tests on every build, but I'm going to tentatively take that as a strong signal that GNU coreutils is still portable across more machines than even Linux can run on.

> I'm going to tentatively take that as a strong signal that GNU coreutils is still portable across more machines than even Linux can run on

And I'm saying -- yes, if "Does it compile?" portability is a value that you care about, the GNU version is probably your version. But what if the Q is (as it was): "Is Rust (llvm?) supported on all platforms Linux targets?"

Then -- I think you need to dig more carefully into what you mean by "support" of non-standard platforms, and why it might be important to you. Would say -- we can move our entire stack to an emulated PDP-11 because Linux and GNU coreutils seem to compile? My guess is no. For lots of reasons, but one reason is "It compiles"/"Seems to work" is not a good measure of support.