Add `: Box<_>` or `::Box<_>` type annotations to various places.

This is the kind of change that one is expected to need to make to
accommodate overloaded-`box`.

----

Note that this is not *all* of the changes necessary to accommodate
Issue 22181.  It is merely the subset of those cases where there was
already a let-binding in place that made it easy to add the necesasry
type ascription.

(For unnamed intermediate `Box` values, one must go down a different
route; `Box::new` is the option that maximizes portability, but has
potential inefficiency depending on whether the call is inlined.)

----

There is one place worth note, `run-pass/coerce-match.rs`, where I
used an ugly form of `Box<_>` type ascription where I would have
preferred to use `Box::new` to accommodate overloaded-`box`.  I
deliberately did not use `Box::new` here, because that is already done
in coerce-match-calls.rs.

----

Precursor for overloaded-`box` and placement-`in`; see Issue 22181.

3 files changed, 6 insertions, 6 deletions

diff --git a/src/libstd/sync/mpsc/mod.rs b/src/libstd/sync/mpsc/mod.rs
index ee8bef50d89..1a1e9e69e71 100644
--- a/src/libstd/sync/mpsc/mod.rs
+++ b/src/libstd/sync/mpsc/mod.rs
@@ -1044,13 +1044,13 @@ mod test {
 
     #[test]
     fn drop_full() {
-        let (tx, _rx) = channel();
+        let (tx, _rx) = channel::<Box<int>>();
         tx.send(box 1).unwrap();
     }
 
     #[test]
     fn drop_full_shared() {
-        let (tx, _rx) = channel();
+        let (tx, _rx) = channel::<Box<int>>();
         drop(tx.clone());
         drop(tx.clone());
         tx.send(box 1).unwrap();
@@ -1389,7 +1389,7 @@ mod test {
     #[test]
     fn oneshot_multi_thread_send_recv_stress() {
         for _ in 0..stress_factor() {
-            let (tx, rx) = channel();
+            let (tx, rx) = channel::<Box<int>>();
             let _t = thread::spawn(move|| {
                 tx.send(box 10).unwrap();
             });
@@ -1566,7 +1566,7 @@ mod sync_tests {
 
     #[test]
     fn drop_full() {
-        let (tx, _rx) = sync_channel(1);
+        let (tx, _rx) = sync_channel::<Box<int>>(1);
         tx.send(box 1).unwrap();
     }
 
diff --git a/src/libstd/sync/mpsc/mpsc_queue.rs b/src/libstd/sync/mpsc/mpsc_queue.rs
index 59fa2e6bc9a..14ed253d8e2 100644
--- a/src/libstd/sync/mpsc/mpsc_queue.rs
+++ b/src/libstd/sync/mpsc/mpsc_queue.rs
@@ -164,7 +164,7 @@ mod tests {
 
     #[test]
     fn test_full() {
-        let q = Queue::new();
+        let q: Queue<Box<_>> = Queue::new();
         q.push(box 1);
         q.push(box 2);
     }
diff --git a/src/libstd/sync/mpsc/spsc_queue.rs b/src/libstd/sync/mpsc/spsc_queue.rs
index ce40fa2672a..3fb13739aa7 100644
--- a/src/libstd/sync/mpsc/spsc_queue.rs
+++ b/src/libstd/sync/mpsc/spsc_queue.rs
@@ -289,7 +289,7 @@ mod test {
     #[test]
     fn drop_full() {
         unsafe {
-            let q = Queue::new(0);
+            let q: Queue<Box<_>> = Queue::new(0);
             q.push(box 1);
             q.push(box 2);
         }