attribute/cfg: What values are set by default?

[kornelski]

The example only shows "linux", but what values are set on other platforms?

How can I check what's my platform's name according to Rust?

Is there a way to target all Unix platforms? (OS X, FreeBSD, etc.)

Is there a way to target x86 and ARM?

[mdinger]

This seems to be documented under Reference/conditional compilation. Looks like you'd use:

#[cfg(any(target_os = "linux", target_os = "freebsd"))]
fn needs_linux_or_freebsd() {}

How nesting is applied isn't completely clear though it states you can.

[mdinger]

Ah, target_family looks like what you need.