Closure type error ui tweak

Do not point at the same span on all notes/help messages, and instead
show them without a span.

Author: estebank

src/librustc/middle/entry.rs

@@ -170,7 +170,7 @@ fn configure_main(this: &mut EntryContext) {
                       defined at the crate level. Either move the definition or \
                       attach the `#[main]` attribute to override this behavior.");
             for &(_, span) in &this.non_main_fns {
-                err.span_note(span, "here is a function named 'main'");
+                err.span_label(span, "here is a function named 'main'");
             }
             err.emit();
             this.session.abort_if_errors();

src/librustc/ty/error.rs

@@ -260,10 +260,8 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 let expected_str = values.expected.sort_string(self);
                 let found_str = values.found.sort_string(self);
                 if expected_str == found_str && expected_str == "closure" {
-                    db.span_note(sp,
-                        "no two closures, even if identical, have the same type");
-                    db.span_help(sp,
-                        "consider boxing your closure and/or using it as a trait object");
+                    db.note("no two closures, even if identical, have the same type");
+                    db.help("consider boxing your closure and/or using it as a trait object");
                 }
             },
             TyParamDefaultMismatch(values) => {

src/test/ui/issue-24036.stderr

@@ -6,16 +6,8 @@ error[E0308]: mismatched types
    |
    = note: expected type `[closure@$DIR/issue-24036.rs:12:17: 12:26]`
               found type `[closure@$DIR/issue-24036.rs:13:9: 13:18]`
-note: no two closures, even if identical, have the same type
-  --> $DIR/issue-24036.rs:13:9
-   |
-13 |     x = |c| c + 1;
-   |         ^^^^^^^^^
-help: consider boxing your closure and/or using it as a trait object
-  --> $DIR/issue-24036.rs:13:9
-   |
-13 |     x = |c| c + 1;
-   |         ^^^^^^^^^
+   = note: no two closures, even if identical, have the same type
+   = help: consider boxing your closure and/or using it as a trait object
 
 error[E0308]: match arms have incompatible types
   --> $DIR/issue-24036.rs:18:13
@@ -31,28 +23,8 @@ error[E0308]: match arms have incompatible types
    |
    = note: expected type `[closure@$DIR/issue-24036.rs:20:14: 20:23]`
               found type `[closure@$DIR/issue-24036.rs:21:14: 21:23]`
-note: no two closures, even if identical, have the same type
-  --> $DIR/issue-24036.rs:18:13
-   |
-18 |       let x = match 1usize {
-   |  _____________^
-19 | |     //~^ ERROR match arms have incompatible types
-20 | |         1 => |c| c + 1,
-21 | |         2 => |c| c - 1,
-22 | |         _ => |c| c - 1
-23 | |     };
-   | |_____^
-help: consider boxing your closure and/or using it as a trait object
-  --> $DIR/issue-24036.rs:18:13
-   |
-18 |       let x = match 1usize {
-   |  _____________^
-19 | |     //~^ ERROR match arms have incompatible types
-20 | |         1 => |c| c + 1,
-21 | |         2 => |c| c - 1,
-22 | |         _ => |c| c - 1
-23 | |     };
-   | |_____^
+   = note: no two closures, even if identical, have the same type
+   = help: consider boxing your closure and/or using it as a trait object
 note: match arm with an incompatible type
   --> $DIR/issue-24036.rs:21:14
    |