Update E0025 to new error format

Author: KiChjang

src/librustc_typeck/check/_match.rs

@@ -675,14 +675,14 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         for &Spanned { node: ref field, span } in fields {
             let field_ty = match used_fields.entry(field.name) {
                 Occupied(occupied) => {
-                    let mut err = struct_span_err!(tcx.sess, span, E0025,
-                                                   "field `{}` bound multiple times \
-                                                    in the pattern",
-                                                   field.name);
-                    span_note!(&mut err, *occupied.get(),
-                               "field `{}` previously bound here",
-                               field.name);
-                    err.emit();
+                    struct_span_err!(tcx.sess, span, E0025,
+                                     "field `{}` bound multiple times \
+                                      in the pattern",
+                                     field.name)
+                        .span_label(span,
+                                    &format!("multiple uses of `{}` in pattern", field.name))
+                        .span_label(*occupied.get(), &format!("first use of `{}`", field.name))
+                        .emit();
                     tcx.types.err
                 }
                 Vacant(vacant) => {

src/test/compile-fail/E0025.rs

@@ -15,5 +15,8 @@ struct Foo {
 
 fn main() {
     let x = Foo { a:1, b:2 };
-    let Foo { a: x, a: y, b: 0 } = x; //~ ERROR E0025
+    let Foo { a: x, a: y, b: 0 } = x;
+    //~^ ERROR field `a` bound multiple times in the pattern
+    //~| NOTE multiple uses of `a` in pattern
+    //~| NOTE first use of `a`
 }

src/test/compile-fail/issue-15260.rs

@@ -14,19 +14,28 @@ struct Foo {
 
 fn main() {
     let Foo {
-        a: _, //~ NOTE field `a` previously bound here
-        a: _ //~ ERROR field `a` bound multiple times in the pattern
+        a: _, //~ NOTE first use of `a`
+        a: _
+        //~^ ERROR field `a` bound multiple times in the pattern
+        //~| NOTE multiple uses of `a` in pattern
     } = Foo { a: 29 };
 
     let Foo {
-        a, //~ NOTE field `a` previously bound here
-        a: _ //~ ERROR field `a` bound multiple times in the pattern
+        a, //~ NOTE first use of `a`
+        a: _
+        //~^ ERROR field `a` bound multiple times in the pattern
+        //~| NOTE multiple uses of `a` in pattern
     } = Foo { a: 29 };
 
     let Foo {
-        a, //~ NOTE field `a` previously bound here
-        //~^ NOTE field `a` previously bound here
-        a: _, //~ ERROR field `a` bound multiple times in the pattern
-        a: x //~ ERROR field `a` bound multiple times in the pattern
+        a,
+        //~^ NOTE first use of `a`
+        //~| NOTE first use of `a`
+        a: _,
+        //~^ ERROR field `a` bound multiple times in the pattern
+        //~| NOTE multiple uses of `a` in pattern
+        a: x
+        //~^ ERROR field `a` bound multiple times in the pattern
+        //~| NOTE multiple uses of `a` in pattern
     } = Foo { a: 29 };
 }