Update E0428 to new format

src/librustc_resolve/lib.rs

@@ -3382,7 +3382,11 @@ impl<'a> Resolver<'a> {
             },
             (true, _) | (_, true) => struct_span_err!(self.session, span, E0260, "{}", msg),
             _ => match (old_binding.is_import(), binding.is_import()) {
-                (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
+                (false, false) => {
+                    let mut e = struct_span_err!(self.session, span, E0428, "{}", msg);
+                    e.span_label(span, &format!("already defined"));
+                    e
+                },
                 (true, true) => {
                     let mut e = struct_span_err!(self.session, span, E0252, "{}", msg);
                     e.span_label(span, &format!("already imported"));

src/test/compile-fail/E0428.rs

@@ -8,9 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-struct Bar;
+struct Bar; //~ previous definition of `Bar` here
+            //~| previous definition of `Bar` here
 struct Bar; //~ ERROR E0428
-            //~^ ERROR E0428
+            //~| NOTE already defined
+            //~| ERROR E0428
+            //~| NOTE already defined
 
 fn main () {
 }

src/test/compile-fail/enum-and-module-in-same-scope.rs

@@ -8,11 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-enum Foo { //~ NOTE previous definition
+enum Foo { //~ NOTE previous definition of `Foo` here
     X
 }
 
 mod Foo { //~ ERROR a type named `Foo` has already been defined
+          //~| NOTE already defined
     pub static X: isize = 42;
     fn f() { f() } // Check that this does not result in a resolution error
 }

src/test/compile-fail/issue-21546.rs

@@ -17,6 +17,7 @@ mod Foo { }
 #[allow(dead_code)]
 struct Foo;
 //~^ ERROR a module named `Foo` has already been defined in this module
+//~| NOTE already defined
 
 #[allow(non_snake_case)]
 mod Bar { }
@@ -25,6 +26,7 @@ mod Bar { }
 #[allow(dead_code)]
 struct Bar(i32);
 //~^ ERROR a module named `Bar` has already been defined
+//~| NOTE already defined
 
 
 #[allow(dead_code)]
@@ -34,6 +36,7 @@ struct Baz(i32);
 #[allow(non_snake_case)]
 mod Baz { }
 //~^ ERROR a type named `Baz` has already been defined
+//~| NOTE already defined
 
 
 #[allow(dead_code)]
@@ -43,6 +46,7 @@ struct Qux { x: bool }
 #[allow(non_snake_case)]
 mod Qux { }
 //~^ ERROR a type named `Qux` has already been defined
+//~| NOTE already defined
 
 
 #[allow(dead_code)]
@@ -52,6 +56,7 @@ struct Quux;
 #[allow(non_snake_case)]
 mod Quux { }
 //~^ ERROR a type named `Quux` has already been defined
+//~| NOTE already defined
 
 
 #[allow(dead_code)]
@@ -61,5 +66,6 @@ enum Corge { A, B }
 #[allow(non_snake_case)]
 mod Corge { }
 //~^ ERROR a type named `Corge` has already been defined
+//~| NOTE already defined
 
 fn main() { }

src/test/compile-fail/trait-duplicate-methods.rs

@@ -11,6 +11,7 @@
 trait Foo {
     fn orange(&self); //~ NOTE previous definition of `orange` here
     fn orange(&self); //~ ERROR a value named `orange` has already been defined in this trait
+                      //~| NOTE already define
 }
 
 fn main() {}