Design of std::os::consts is unmaintainable/unspeccable

[brson]

This module looks vaguelly like

pub mod os {
  pub mod consts {
    ... various reexports ...

    pub mod android { ... }
    pub mod linux { .... }
  }
}

All constants for all platforms are available to all platforms. There is no bound to the number of public modules that must be added here over time, and doubtless different implementations of Rust must support different platforms. In other words, as designed this module will never stop changing. This is a mess waiting to happen. I suggest only exposing the current arch and moving any necessary cross-arch capability into rustc directly. Nominating.

[pnkfelix]

Assigning 1.0, P-backcompat-libs.

[pongad]

@brson I'll be happy to try this. I'm not quite sure what you want the outcome to be though; I'll find you on the IRC.

[brson]

@pongad I want the outcome to be that os::consts defines only a single set of constants for FAMILY, etc., so it should look essentially like

mod consts {
    static FAMILY: &'static str = "unix";
    static SYSNAME: &'static str = "linux";
    ...
}

And in fact could even be defined using cfg attributes on mod const like

#[cfg(target_os = "linux")]
mod consts {
    static FAMILY: &'static str = "unix";
    static SYSNAME: &'static str = "linux";
    ...
}

Just making this change will probably break parts of rustc that do want to know this information for all platforms. I would then just duplicate the constants directly in rustc.