auto merge of #19169 : aturon/rust/fds, r=alexcrichton

This PR adds some internal infrastructure to allow the private `std::sys` module to access internal representation details of `std::io`.

It then exposes those details in two new, platform-specific API surfaces: `std::os::unix` and `std::os::windows`.

To start with, these will provide the ability to extract file descriptors, HANDLEs, SOCKETs, and so on from `std::io` types.

More functionality, and more specific platforms (e.g. `std::os::linux`) will be added over time.

Closes #18897

1 files changed, 4 insertions, 5 deletions

diff --git a/src/libstd/sys/common/mod.rs b/src/libstd/sys/common/mod.rs
index 77edd7c5c4e..e382ec261a0 100644
--- a/src/libstd/sys/common/mod.rs
+++ b/src/libstd/sys/common/mod.rs
@@ -13,7 +13,7 @@
 
 use io::{mod, IoError, IoResult};
 use prelude::*;
-use sys::{last_error, retry, fs};
+use sys::{last_error, retry};
 use c_str::CString;
 use num::Int;
 use path::BytesContainer;
@@ -84,10 +84,9 @@ pub fn keep_going(data: &[u8], f: |*const u8, uint| -> i64) -> i64 {
     return (origamt - amt) as i64;
 }
 
-// traits for extracting representations from
-
-pub trait AsFileDesc {
-    fn as_fd(&self) -> &fs::FileDesc;
+// A trait for extracting representations from std::io types
+pub trait AsInner<Inner> {
+    fn as_inner(&self) -> &Inner;
 }
 
 pub trait ProcessConfig<K: BytesContainer, V: BytesContainer> {