Rebase conflicts from this giant stack of patches

List of PRs contained in this rollup:

Closes #12167 r=alexcrichton
Closes #12200 r=alexcrichton
Closes #12206 r=pcwalton
Closes #12209 r=huonw
Closes #12211 r=pcwalton
Closes #12217 r=brson
Closes #12218 r=alexcrichton
Closes #12220 r=alexcrichton
Closes #12222 r=kballard
Closes #12225 r=alexcrichton
Closes #12227 r=kballard
Closes #12237 r=alexcrichton
Closes #12240 r=kballard

src/libstd/comm/select.rs

@@ -531,7 +531,7 @@ mod test {
         let (p, c) = Chan::new();
         c.send(());
         select!(
-            () = p.recv() => {},
+            () = p.recv() => {}
         )
     })
 
@@ -540,7 +540,7 @@ mod test {
         c.send(());
         c.send(());
         select!(
-            () = p.recv() => {},
+            () = p.recv() => {}
         )
     })
 
@@ -549,7 +549,7 @@ mod test {
         drop(c.clone());
         c.send(());
         select!(
-            () = p.recv() => {},
+            () = p.recv() => {}
         )
     })