stty: refine target configuration

[xtqqczze]

• Refine the stty target configuration to explicitly exclude unsupported platforms, skipping compilation where it would otherwise fail.
• Add missing rustix/fs feature.

$ cargo check -q -p uu_stty
error[E0433]: cannot find `fs` in `rustix`
   --> src/uu/stty/src/stty.rs:249:47
    |
249 |                         .custom_flags(rustix::fs::OFlags::NONBLOCK.bits() as i32)
    |                                               ^^ could not find `fs` in `rustix`
    |
note: found an item that was configured out
   --> ~/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/rustix-1.1.5/src/lib.rs:223:9
    |
221 | #[cfg(feature = "fs")]
    |       -------------- the item is gated behind the `fs` feature
222 | #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
223 | pub mod fs;
    |         ^^
note: found an item that was configured out
   --> ~/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/rustix-1.1.5/src/lib.rs:342:16
    |
330 |     linux_raw,
    |     --------- the item is gated here
...
342 | pub(crate) mod fs;
    |                ^^

Relates to: #14912.

[oech3]

Missing clap means we cannot build anyway. Is this worth to increase complexity?

[xtqqczze]

seems less complex to be explicit about configuration

[oech3]

Why? not(unix) is much simpler and we cannot support aix in any cases.

[xtqqczze]

Missing clap means we cannot build anyway

what do you mean by this?

[oech3]

All of our utility depends on clap. So there is no reason to cfg out it.

[xtqqczze]

To add check-only CI for less common targets, it would be helpful if commands like the following could succeed:

RUSTC_BOOTSTRAP=1 cargo hack clippy -Zbuild-std \
  --quiet --workspace --all-features \
  --target=powerpc64-ibm-aix

[oech3]

But build-std is high cost to run on the all CI. Is threre any pre-built std we can use?

[xtqqczze]

That's just an example, -Zbuild-std wouldn't be necessary for most targets.

[oech3]

Do you just want to avoid fetching unnecessary crates? Then, this change is making a sense.

[xtqqczze]

Avoiding fetching unnecessary crates is another benefit.

[xtqqczze]

@oech3 Would you rebase #15299 onto this to fix the compiler errors?

[oech3]

after one of them was merged

[xtqqczze]

@oech3 this should merge before #15299 as uu_stty doesn't currently compile (fails since #15331)

[oech3]

I take rustix::fs of Cargo.toml only. Change for aix should be different PR.

[oech3]

How about merging this by yourself since this looks serious? Collaborator has priv to merge this.

[xtqqczze]

No I do not write permissions on main; I've already requested @sylvestre review.