introduce a linux android macro

[sylvestre]

No description provided.

[ChrisDryden]

I'm not able to identify why this doesn't work in the CI, did you investigate using cfg-aliases? #9559

[ChrisDryden]

Did some further research, its failing because the #[cfg(...)] attribute evaluates based on the host machine (where the build script runs), not the target machine.

This should work:

  if let Ok(target_os) = env::var("CARGO_CFG_TARGET_OS") {
      if target_os == "linux" || target_os == "android" {
          println!("cargo:rustc-cfg=linux_android");
      }
  }

I would love to do something similar for all of the BSD os's, it would make stty much cleaner and easier to read

[ChrisDryden]

Actually two issues here, the cross compilation and that this will only set that config for the parent crate and you would need this in a build.rs for every crate to do this. How about adding this to the Cargo.toml instead?

[target.'cfg(any(target_os = "linux", target_os = "android"))']
rustflags = ["--cfg", "linux_android"]

[ChrisDryden]

Actually that Cargo.toml rustflags is not ideal either since it wont work for anyone that wants to use any of the utilities as a dependency. Not really any great options here.

[sylvestre]

probably why we haven't done it before :)

[oech3]

cfg-aliases is a dep of nix. No reason to avoid it (if works).

[xtqqczze]

I know the name linux_android matches that in nix/nix-rust but I think it's a little unclear.

[oech3]

linux_kernel?

[xtqqczze]

linux_kernel?

That's what bytecodealliance/rustix uses and much clearer.

[xtqqczze]

Other suggestions, linux-targets, linux-all, linux-abi or simplylinux?

[xtqqczze]

linux_kernel?

That's what bytecodealliance/rustix uses and much clearer.

Might be worth considering that Android might not always use a linux kernel. For example, a future release of Android might be based on starnix which uses fuchsia.

So linux-abi might be the most technically correct option.

[xtqqczze]

I'm leaning toward linux for simplicity and to align with the approach for bsd in #10443