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.

Author: pnkfelix

src/liballoc/arc.rs

@@ -69,6 +69,8 @@
 //! }
 //! ```
 
+use boxed::Box;
+
 use core::prelude::*;
 
 use core::atomic;
@@ -170,7 +172,7 @@ impl<T> Arc<T> {
     pub fn new(data: T) -> Arc<T> {
         // Start the weak pointer count as 1 which is the weak pointer that's
         // held by all the strong pointers (kinda), see std/rc.rs for more info
-        let x = box ArcInner {
+        let x: Box<_> = box ArcInner {
             strong: atomic::AtomicUsize::new(1),
             weak: atomic::AtomicUsize::new(1),
             data: data,

src/liballoc/heap.rs

@@ -387,6 +387,7 @@ mod test {
     extern crate test;
     use self::test::Bencher;
     use core::ptr::PtrExt;
+    use boxed::Box;
     use heap;
 
     #[test]
@@ -404,7 +405,7 @@ mod test {
     #[bench]
     fn alloc_owned_small(b: &mut Bencher) {
         b.iter(|| {
-            box 10
+            let _: Box<_> = box 10;
         })
     }
 }

src/liballoc/lib.rs

@@ -96,9 +96,15 @@ pub mod heap;
 
 // Primitive types using the heaps above
 
+// Need to conditionally define the mod from `boxed.rs` to avoid
+// duplicating the lang-items when building in test cfg; but also need
+// to allow code to have `use boxed::HEAP;`
+// and `use boxed::Box;` declarations.
 #[cfg(not(test))]
 pub mod boxed;
 #[cfg(test)]
+mod boxed { pub use std::boxed::{Box, HEAP}; }
+#[cfg(test)]
 mod boxed_test;
 pub mod arc;
 pub mod rc;

src/liballoc/rc.rs

@@ -795,6 +795,7 @@ impl<T> RcBoxPtr<T> for Weak<T> {
 #[cfg(test)]
 mod tests {
     use super::{Rc, Weak, weak_count, strong_count};
+    use std::boxed::Box;
     use std::cell::RefCell;
     use std::option::Option;
     use std::option::Option::{Some, None};
@@ -826,7 +827,7 @@ mod tests {
 
     #[test]
     fn test_destructor() {
-        let x = Rc::new(box 5);
+        let x: Rc<Box<_>> = Rc::new(box 5);
         assert_eq!(**x, 5);
     }
 

src/libarena/lib.rs

@@ -581,11 +581,11 @@ mod tests {
     #[bench]
     pub fn bench_copy_nonarena(b: &mut Bencher) {
         b.iter(|| {
-            box Point {
+            let _: Box<_> = box Point {
                 x: 1,
                 y: 2,
                 z: 3,
-            }
+            };
         })
     }
 
@@ -634,10 +634,10 @@ mod tests {
     #[bench]
     pub fn bench_noncopy_nonarena(b: &mut Bencher) {
         b.iter(|| {
-            box Noncopy {
+            let _: Box<_> = box Noncopy {
                 string: "hello world".to_string(),
                 array: vec!( 1, 2, 3, 4, 5 ),
-            }
+            };
         })
     }
 

src/libcollections/binary_heap.rs

@@ -790,7 +790,7 @@ mod tests {
 
     #[test]
     fn test_push_unique() {
-        let mut heap = BinaryHeap::from_vec(vec![box 2, box 4, box 9]);
+        let mut heap = BinaryHeap::<Box<_>>::from_vec(vec![box 2, box 4, box 9]);
         assert_eq!(heap.len(), 3);
         assert!(*heap.peek().unwrap() == box 9);
         heap.push(box 11);

src/libcollections/linked_list.rs

@@ -984,7 +984,7 @@ mod tests {
 
     #[test]
     fn test_basic() {
-        let mut m = LinkedList::new();
+        let mut m = LinkedList::<Box<_>>::new();
         assert_eq!(m.pop_front(), None);
         assert_eq!(m.pop_back(), None);
         assert_eq!(m.pop_front(), None);

src/libcollections/slice.rs

@@ -1509,6 +1509,7 @@ fn merge_sort<T, F>(v: &mut [T], mut compare: F) where F: FnMut(&T, &T) -> Order
 
 #[cfg(test)]
 mod tests {
+    use alloc::boxed::Box;
     use core::cmp::Ordering::{Greater, Less, Equal};
     use core::prelude::{Some, None, Clone};
     use core::prelude::{Iterator, IteratorExt};
@@ -1799,7 +1800,7 @@ mod tests {
     #[test]
     fn test_swap_remove_noncopyable() {
         // Tests that we don't accidentally run destructors twice.
-        let mut v = Vec::new();
+        let mut v: Vec<Box<_>> = Vec::new();
         v.push(box 0u8);
         v.push(box 0u8);
         v.push(box 0u8);
@@ -1828,7 +1829,7 @@ mod tests {
 
     #[test]
     fn test_truncate() {
-        let mut v = vec![box 6,box 5,box 4];
+        let mut v: Vec<Box<_>> = vec![box 6,box 5,box 4];
         v.truncate(1);
         let v = v;
         assert_eq!(v.len(), 1);
@@ -1838,7 +1839,7 @@ mod tests {
 
     #[test]
     fn test_clear() {
-        let mut v = vec![box 6,box 5,box 4];
+        let mut v: Vec<Box<_>> = vec![box 6,box 5,box 4];
         v.clear();
         assert_eq!(v.len(), 0);
         // If the unsafe block didn't drop things properly, we blow up here.
@@ -1863,11 +1864,11 @@ mod tests {
 
     #[test]
     fn test_dedup_unique() {
-        let mut v0 = vec![box 1, box 1, box 2, box 3];
+        let mut v0: Vec<Box<_>> = vec![box 1, box 1, box 2, box 3];
         v0.dedup();
-        let mut v1 = vec![box 1, box 2, box 2, box 3];
+        let mut v1: Vec<Box<_>> = vec![box 1, box 2, box 2, box 3];
         v1.dedup();
-        let mut v2 = vec![box 1, box 2, box 3, box 3];
+        let mut v2: Vec<Box<_>> = vec![box 1, box 2, box 3, box 3];
         v2.dedup();
         /*
          * If the boxed pointers were leaked or otherwise misused, valgrind
@@ -1877,11 +1878,11 @@ mod tests {
 
     #[test]
     fn test_dedup_shared() {
-        let mut v0 = vec![box 1, box 1, box 2, box 3];
+        let mut v0: Vec<Box<_>> = vec![box 1, box 1, box 2, box 3];
         v0.dedup();
-        let mut v1 = vec![box 1, box 2, box 2, box 3];
+        let mut v1: Vec<Box<_>> = vec![box 1, box 2, box 2, box 3];
         v1.dedup();
-        let mut v2 = vec![box 1, box 2, box 3, box 3];
+        let mut v2: Vec<Box<_>> = vec![box 1, box 2, box 3, box 3];
         v2.dedup();
         /*
          * If the pointers were leaked or otherwise misused, valgrind and/or
@@ -2254,8 +2255,9 @@ mod tests {
     #[test]
     #[should_fail]
     fn test_permute_fail() {
-        let v = [(box 0, Rc::new(0)), (box 0, Rc::new(0)),
-                 (box 0, Rc::new(0)), (box 0, Rc::new(0))];
+        let v: [(Box<_>, Rc<_>); 4] =
+            [(box 0, Rc::new(0)), (box 0, Rc::new(0)),
+             (box 0, Rc::new(0)), (box 0, Rc::new(0))];
         let mut i = 0;
         for _ in v.permutations() {
             if i == 2 {
@@ -2849,7 +2851,7 @@ mod tests {
 
     #[test]
     fn test_to_vec() {
-        let xs = box [1, 2, 3];
+        let xs: Box<_> = box [1, 2, 3];
         let ys = xs.to_vec();
         assert_eq!(ys, [1, 2, 3]);
     }

src/libcollections/vec.rs

@@ -2130,8 +2130,8 @@ mod tests {
     #[test]
     fn test_clone_from() {
         let mut v = vec!();
-        let three = vec!(box 1, box 2, box 3);
-        let two = vec!(box 4, box 5);
+        let three: Vec<Box<_>> = vec!(box 1, box 2, box 3);
+        let two: Vec<Box<_>> = vec!(box 4, box 5);
         // zero, long
         v.clone_from(&three);
         assert_eq!(v, three);

src/libcollections/vec_map.rs

@@ -1205,7 +1205,7 @@ mod test_map {
 
     #[test]
     fn test_move_iter() {
-        let mut m = VecMap::new();
+        let mut m: VecMap<Box<_>> = VecMap::new();
         m.insert(1, box 2);
         let mut called = false;
         for (k, v) in m {

src/libcoretest/any.rs

@@ -68,7 +68,7 @@ fn any_downcast_ref() {
 #[test]
 fn any_downcast_mut() {
     let mut a = 5_usize;
-    let mut b = box 7_usize;
+    let mut b: Box<_> = box 7_usize;
 
     let a_r = &mut a as &mut Any;
     let tmp: &mut uint = &mut *b;

src/libcoretest/option.rs

@@ -16,7 +16,7 @@ use core::clone::Clone;
 #[test]
 fn test_get_ptr() {
     unsafe {
-        let x = box 0;
+        let x: Box<_> = box 0;
         let addr_x: *const int = mem::transmute(&*x);
         let opt = Some(x);
         let y = opt.unwrap();

src/librustc_back/sha2.rs

@@ -606,7 +606,7 @@ mod tests {
 
         let tests = wikipedia_tests;
 
-        let mut sh = box Sha256::new();
+        let mut sh: Box<_> = box Sha256::new();
 
         test_hash(&mut *sh, &tests);
     }

src/libstd/old_io/net/ip.rs

@@ -323,22 +323,22 @@ impl<'a> Parser<'a> {
     }
 
     fn read_ip_addr(&mut self) -> Option<IpAddr> {
-        let ipv4_addr = |p: &mut Parser| p.read_ipv4_addr();
-        let ipv6_addr = |p: &mut Parser| p.read_ipv6_addr();
-        self.read_or(&mut [box ipv4_addr, box ipv6_addr])
+        let ipv4_addr: Box<_> = box |p: &mut Parser| p.read_ipv4_addr();
+        let ipv6_addr: Box<_> = box |p: &mut Parser| p.read_ipv6_addr();
+        self.read_or(&mut [ipv4_addr, ipv6_addr])
     }
 
     fn read_socket_addr(&mut self) -> Option<SocketAddr> {
         let ip_addr = |p: &mut Parser| {
-            let ipv4_p = |p: &mut Parser| p.read_ip_addr();
-            let ipv6_p = |p: &mut Parser| {
+            let ipv4_p: Box<_> = box |p: &mut Parser| p.read_ip_addr();
+            let ipv6_p: Box<_> = box |p: &mut Parser| {
                 let open_br = |p: &mut Parser| p.read_given_char('[');
                 let ip_addr = |p: &mut Parser| p.read_ipv6_addr();
                 let clos_br = |p: &mut Parser| p.read_given_char(']');
                 p.read_seq_3::<char, IpAddr, char, _, _, _>(open_br, ip_addr, clos_br)
                         .map(|t| match t { (_, ip, _) => ip })
             };
-            p.read_or(&mut [box ipv4_p, box ipv6_p])
+            p.read_or(&mut [ipv4_p, ipv6_p])
         };
         let colon = |p: &mut Parser| p.read_given_char(':');
         let port  = |p: &mut Parser| p.read_number(10, 5, 0x10000).map(|n| n as u16);

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();
     }
 

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);
     }

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);
         }

src/libstd/thread.rs

@@ -804,7 +804,7 @@ mod test {
     fn avoid_copying_the_body<F>(spawnfn: F) where F: FnOnce(Thunk<'static>) {
         let (tx, rx) = channel();
 
-        let x = box 1;
+        let x: Box<_> = box 1;
         let x_in_parent = (&*x) as *const i32 as usize;
 
         spawnfn(Thunk::new(move|| {

src/test/bench/shootout-k-nucleotide.rs

@@ -146,7 +146,7 @@ impl Table {
     fn search_remainder<C:TableCallback>(item: &mut Entry, key: Code, c: C) {
         match item.next {
             None => {
-                let mut entry = box Entry {
+                let mut entry: Box<_> = box Entry {
                     code: key,
                     count: 0,
                     next: None,
@@ -170,7 +170,7 @@ impl Table {
 
         {
             if self.items[index as usize].is_none() {
-                let mut entry = box Entry {
+                let mut entry: Box<_> = box Entry {
                     code: key,
                     count: 0,
                     next: None,

src/test/bench/sudoku.rs

@@ -124,7 +124,7 @@ impl Sudoku {
     fn next_color(&mut self, row: u8, col: u8, start_color: u8) -> bool {
         if start_color < 10u8 {
             // colors not yet used
-            let mut avail = box Colors::new(start_color);
+            let mut avail: Box<_> = box Colors::new(start_color);
 
             // drop colors already in use in neighbourhood
             self.drop_colors(&mut *avail, row, col);

src/test/compile-fail/borrow-tuple-fields.rs

@@ -16,7 +16,7 @@ struct Foo(Box<isize>, isize);
 struct Bar(isize, isize);
 
 fn main() {
-    let x = (box 1, 2);
+    let x: (Box<_>, _) = (box 1, 2);
     let r = &x.0;
     let y = x; //~ ERROR cannot move out of `x` because it is borrowed
 

src/test/compile-fail/borrowck-bad-nested-calls-free.rs

@@ -23,7 +23,7 @@ fn add(v: &usize, w: usize) -> usize {
 }
 
 fn implicit() {
-    let mut a = box 1;
+    let mut a: Box<_> = box 1;
 
     // Note the danger here:
     //
@@ -36,7 +36,7 @@ fn implicit() {
 }
 
 fn explicit() {
-    let mut a = box 1;
+    let mut a: Box<_> = box 1;
     add(
         &*a,
         rewrite(&mut a)); //~ ERROR cannot borrow