std: Second pass stabilization for `comm`

This commit is a second pass stabilization for the `std::comm` module,
performing the following actions:

* The entire `std::comm` module was moved under `std::sync::mpsc`. This movement
  reflects that channels are just yet another synchronization primitive, and
  they don't necessarily deserve a special place outside of the other
  concurrency primitives that the standard library offers.
* The `send` and `recv` methods have all been removed.
* The `send_opt` and `recv_opt` methods have been renamed to `send` and `recv`.
  This means that all send/receive operations return a `Result` now indicating
  whether the operation was successful or not.
* The error type of `send` is now a `SendError` to implement a custom error
  message and allow for `unwrap()`. The error type contains an `into_inner`
  method to extract the value.
* The error type of `recv` is now `RecvError` for the same reasons as `send`.
* The `TryRecvError` and `TrySendError` types have had public reexports removed
  of their variants and the variant names have been tweaked with enum
  namespacing rules.
* The `Messages` iterator is renamed to `Iter`

This functionality is now all `#[stable]`:

* `Sender`
* `SyncSender`
* `Receiver`
* `std::sync::mpsc`
* `channel`
* `sync_channel`
* `Iter`
* `Sender::send`
* `Sender::clone`
* `SyncSender::send`
* `SyncSender::try_send`
* `SyncSender::clone`
* `Receiver::recv`
* `Receiver::try_recv`
* `Receiver::iter`
* `SendError`
* `RecvError`
* `TrySendError::{mod, Full, Disconnected}`
* `TryRecvError::{mod, Empty, Disconnected}`
* `SendError::into_inner`
* `TrySendError::into_inner`

This is a breaking change due to the modification of where this module is
located, as well as the changing of the semantics of `send` and `recv`. Most
programs just need to rename imports of `std::comm` to `std::sync::mpsc` and
add calls to `unwrap` after a send or a receive operation.

[breaking-change]

3 files changed, 15 insertions, 15 deletions

diff --git a/src/libstd/sys/common/helper_thread.rs b/src/libstd/sys/common/helper_thread.rs
index 5d94e8efeb8..b9dc5f0e398 100644
--- a/src/libstd/sys/common/helper_thread.rs
+++ b/src/libstd/sys/common/helper_thread.rs
@@ -23,10 +23,10 @@
 use prelude::v1::*;
 
 use cell::UnsafeCell;
-use comm::{channel, Sender, Receiver};
 use mem;
 use rt;
 use sync::{StaticMutex, StaticCondvar};
+use sync::mpsc::{channel, Sender, Receiver};
 use sys::helper_signal;
 
 use thread::Thread;
@@ -118,7 +118,7 @@ impl<M: Send> Helper<M> {
             // message. Otherwise it could wake up and go to sleep before we
             // send the message.
             assert!(!self.chan.get().is_null());
-            (**self.chan.get()).send(msg);
+            (**self.chan.get()).send(msg).unwrap();
             helper_signal::signal(*self.signal.get() as helper_signal::signal);
         }
     }
diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs
index 9824c9c7364..a11fe3487a8 100644
--- a/src/libstd/sys/unix/process.rs
+++ b/src/libstd/sys/unix/process.rs
@@ -13,7 +13,6 @@ use self::Req::*;
 
 use c_str::{CString, ToCStr};
 use collections;
-use comm::{channel, Sender, Receiver};
 use hash::Hash;
 use io::process::{ProcessExit, ExitStatus, ExitSignal};
 use io::{mod, IoResult, IoError, EndOfFile};
@@ -22,6 +21,7 @@ use mem;
 use os;
 use path::BytesContainer;
 use ptr;
+use sync::mpsc::{channel, Sender, Receiver};
 use sys::fs::FileDesc;
 use sys::{mod, retry, c, wouldblock, set_nonblocking, ms_to_timeval};
 use sys_common::helper_thread::Helper;
@@ -277,8 +277,8 @@ impl Process {
     }
 
     pub fn wait(&self, deadline: u64) -> IoResult<ProcessExit> {
-        use std::cmp;
-        use std::comm;
+        use cmp;
+        use sync::mpsc::TryRecvError;
 
         static mut WRITE_FD: libc::c_int = 0;
 
@@ -337,9 +337,9 @@ impl Process {
 
         let (tx, rx) = channel();
         unsafe { HELPER.send(NewChild(self.pid, tx, deadline)); }
-        return match rx.recv_opt() {
+        return match rx.recv() {
             Ok(e) => Ok(e),
-            Err(()) => Err(timeout("wait timed out")),
+            Err(..) => Err(timeout("wait timed out")),
         };
 
         // Register a new SIGCHLD handler, returning the reading half of the
@@ -420,11 +420,11 @@ impl Process {
                             Ok(NewChild(pid, tx, deadline)) => {
                                 active.push((pid, tx, deadline));
                             }
-                            Err(comm::Disconnected) => {
+                            Err(TryRecvError::Disconnected) => {
                                 assert!(active.len() == 0);
                                 break 'outer;
                             }
-                            Err(comm::Empty) => break,
+                            Err(TryRecvError::Empty) => break,
                         }
                     }
                 }
@@ -460,7 +460,7 @@ impl Process {
                     active.retain(|&(pid, ref tx, _)| {
                         let pr = Process { pid: pid };
                         match pr.try_wait() {
-                            Some(msg) => { tx.send(msg); false }
+                            Some(msg) => { tx.send(msg).unwrap(); false }
                             None => true,
                         }
                     });
diff --git a/src/libstd/sys/unix/timer.rs b/src/libstd/sys/unix/timer.rs
index 903c4954f6f..4afe13d8735 100644
--- a/src/libstd/sys/unix/timer.rs
+++ b/src/libstd/sys/unix/timer.rs
@@ -49,13 +49,13 @@
 use prelude::v1::*;
 use self::Req::*;
 
-use comm::{mod, channel, Sender, Receiver};
 use io::IoResult;
 use libc;
 use mem;
 use os;
 use ptr;
 use sync::atomic;
+use sync::mpsc::{channel, Sender, Receiver, TryRecvError};
 use sys::c;
 use sys::fs::FileDesc;
 use sys_common::helper_thread::Helper;
@@ -168,7 +168,7 @@ fn helper(input: libc::c_int, messages: Receiver<Req>, _: ()) {
             1 => {
                 loop {
                     match messages.try_recv() {
-                        Err(comm::Disconnected) => {
+                        Err(TryRecvError::Disconnected) => {
                             assert!(active.len() == 0);
                             break 'outer;
                         }
@@ -179,7 +179,7 @@ fn helper(input: libc::c_int, messages: Receiver<Req>, _: ()) {
                             match dead.iter().position(|&(i, _)| id == i) {
                                 Some(i) => {
                                     let (_, i) = dead.remove(i).unwrap();
-                                    ack.send(i);
+                                    ack.send(i).unwrap();
                                     continue
                                 }
                                 None => {}
@@ -187,7 +187,7 @@ fn helper(input: libc::c_int, messages: Receiver<Req>, _: ()) {
                             let i = active.iter().position(|i| i.id == id);
                             let i = i.expect("no timer found");
                             let t = active.remove(i).unwrap();
-                            ack.send(t);
+                            ack.send(t).unwrap();
                         }
                         Err(..) => break
                     }
@@ -271,7 +271,7 @@ impl Timer {
             None => {
                 let (tx, rx) = channel();
                 HELPER.send(RemoveTimer(self.id, tx));
-                rx.recv()
+                rx.recv().unwrap()
             }
         }
     }