Make hint clearer, with the potential of being wrong

Author: estebank

src/libcore/marker.rs

@@ -346,11 +346,11 @@ pub trait Copy : Clone {
 #[rustc_on_unimplemented(
     on(
         _Self="std::sync::mpsc::Receiver<T>",
-        label="`{Self}` cannot be shared safely, if using a closure consider marking it `move`"
+        label="`{Self}` cannot be shared safely, consider marking the closure `move`"
     ),
     on(
         _Self="std::sync::mpsc::Sender<T>",
-        label="`{Self}` cannot be shared safely, if using a closure consider marking it `move`"
+        label="`{Self}` cannot be shared safely, consider marking the closure `move`"
     ),
     message="`{Self}` cannot be shared between threads safely",
     label="`{Self}` cannot be shared between threads safely"

src/test/ui/closure-move-sync.stderr

@@ -2,7 +2,7 @@ error[E0277]: `std::sync::mpsc::Receiver<()>` cannot be shared between threads s
   --> $DIR/closure-move-sync.rs:16:13
    |
 16 |     let t = thread::spawn(|| {
-   |             ^^^^^^^^^^^^^ `std::sync::mpsc::Receiver<()>` cannot be shared safely, if using a closure consider marking it `move`
+   |             ^^^^^^^^^^^^^ `std::sync::mpsc::Receiver<()>` cannot be shared safely, consider marking the closure `move`
    |
    = help: the trait `std::marker::Sync` is not implemented for `std::sync::mpsc::Receiver<()>`
    = note: required because of the requirements on the impl of `std::marker::Send` for `&std::sync::mpsc::Receiver<()>`
@@ -13,7 +13,7 @@ error[E0277]: `std::sync::mpsc::Sender<()>` cannot be shared between threads saf
   --> $DIR/closure-move-sync.rs:28:5
    |
 28 |     thread::spawn(|| tx.send(()).unwrap());
-   |     ^^^^^^^^^^^^^ `std::sync::mpsc::Sender<()>` cannot be shared safely, if using a closure consider marking it `move`
+   |     ^^^^^^^^^^^^^ `std::sync::mpsc::Sender<()>` cannot be shared safely, consider marking the closure `move`
    |
    = help: the trait `std::marker::Sync` is not implemented for `std::sync::mpsc::Sender<()>`
    = note: required because of the requirements on the impl of `std::marker::Send` for `&std::sync::mpsc::Sender<()>`