doc: Be more specific about how to box closures

Author: richo

src/librustc/middle/ty.rs

@@ -5151,8 +5151,7 @@ pub fn note_and_explain_type_err<'tcx>(cx: &ctxt<'tcx>, err: &type_err<'tcx>, sp
             if expected_str == found_str && expected_str == "closure" {
                 cx.sess.span_note(sp, &format!("no two closures, even if identical, have the same \
                                                 type"));
-                cx.sess.span_help(sp, &format!("consider boxing your closure and/or \
-                                        using it as a trait object"));
+                cx.sess.span_help(sp, &format!("consider boxing your closure as a trait object"));
             }
         }
         _ => {}

src/test/compile-fail/issue-24036.rs

@@ -13,7 +13,7 @@ fn closure_to_loc() {
     x = |c| c + 1;
     //~^ ERROR mismatched types
     //~| NOTE no two closures, even if identical, have the same type
-    //~| HELP consider boxing your closure and/or using it as a trait object
+    //~| HELP consider boxing your closure as a trait object
 }
 
 fn closure_from_match() {
@@ -24,7 +24,7 @@ fn closure_from_match() {
     };
     //~^^^^^ ERROR match arms have incompatible types
     //~| NOTE no two closures, even if identical, have the same type
-    //~| HELP consider boxing your closure and/or using it as a trait object
+    //~| HELP consider boxing your closure as a trait object
 }
 
 fn main() { }