Can't compile "libc.rs" for iOS

[kud1ing]

src/libstd/libc.rs:2937:17: 2937:50 error: unresolved import: could not find `arch` in `libc::types::os`.
src/libstd/libc.rs:2937             use libc::types::os::arch::c95::c_int;
                                                                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/libstd/libc.rs:2937:17: 2937:50 error: failed to resolve import `libc::types::os::arch::c95::c_int`
src/libstd/libc.rs:2937             use libc::types::os::arch::c95::c_int;
                                                                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...

[kud1ing]

https://github.com/mozilla/rust/blob/master/src/libstd/libc.rs#L1163 etc. probably needs an additional #[cfg(target_arch = "arm")].

Compare with Android: https://github.com/mozilla/rust/blob/master/src/libstd/libc.rs#L305

[adrientetar]

@kud1ing I would maybe start by looking at the modules tagged under #[cfg(target_os = android)] althrough android might be different because it uses bionic there are fields that seem common to various OSes.
e.g. https://github.com/mozilla/rust/blob/master/src/libstd/libc.rs#L3392

[kud1ing]

One gets an overview of the cases with grep -Irsnw "pub mod\|cfg" libc.rs.