Rollup merge of #22567 - Gankro:unstable, r=alexcrichton

 * Adds features and allows
* Removes unused muts, unused imports, dead code
* Migrates some deprecated code to new io/env
* Changes std::num::uint/int to be re-exports of std::num::usize/isize

libcollections, liballoc, and libcoretest no longer warn during testing.

libstd warns much less, though there's some dangly bits that weren't obvious fixes. In particular, how to only supress deprecated warnings in specific submodules of std.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libstd/thread.rs b/src/libstd/thread.rs
index 1c64b6961d7..1f70e1526a0 100644
--- a/src/libstd/thread.rs
+++ b/src/libstd/thread.rs
@@ -702,7 +702,7 @@ mod test {
     use boxed::BoxAny;
     use result;
     use std::old_io::{ChanReader, ChanWriter};
-    use super::{Thread, Builder};
+    use super::{Builder};
     use thread;
     use thunk::Thunk;
     use time::Duration;
@@ -767,7 +767,7 @@ mod test {
     #[test]
     #[should_fail]
     fn test_scoped_implicit_panic() {
-        thread::scoped(|| panic!());
+        let _ = thread::scoped(|| panic!());
     }
 
     #[test]