Rollup merge of #35507 - hank-der-hafenarbeiter:master, r=jonathandturner

Updated Error mesage to new format for E0221

Part of #35386
r? @jonathandturner

Author: Jonathan Turner

src/librustc_typeck/astconv.rs

@@ -1287,10 +1287,12 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
         }
 
         if bounds.len() > 1 {
-            let mut err = struct_span_err!(self.tcx().sess, span, E0221,
-                                           "ambiguous associated type `{}` in bounds of `{}`",
-                                           assoc_name,
-                                           ty_param_name);
+            let mut err = struct_span_err!(
+                self.tcx().sess, span, E0221,
+                "ambiguous associated type `{}` in bounds of `{}`",
+                assoc_name,
+                ty_param_name);
+            err.span_label(span, &format!("ambiguous associated type `{}`", assoc_name));
 
             for bound in &bounds {
                 span_note!(&mut err, span,

src/test/compile-fail/associated-type-projection-from-multiple-supertraits.rs

@@ -28,20 +28,23 @@ pub trait BoxCar : Box + Vehicle {
 
 fn dent<C:BoxCar>(c: C, color: C::Color) {
     //~^ ERROR ambiguous associated type `Color` in bounds of `C`
+    //~| NOTE ambiguous associated type `Color`
     //~| NOTE could derive from `Vehicle`
     //~| NOTE could derive from `Box`
 }
 
 fn dent_object<COLOR>(c: BoxCar<Color=COLOR>) {
     //~^ ERROR ambiguous associated type
     //~| ERROR the value of the associated type `Color` (from the trait `Vehicle`) must be specified
+    //~| NOTE ambiguous associated type `Color`
     //~| NOTE could derive from `Vehicle`
     //~| NOTE could derive from `Box`
     //~| NOTE missing associated type `Color` value
 }
 
 fn paint<C:BoxCar>(c: C, d: C::Color) {
     //~^ ERROR ambiguous associated type `Color` in bounds of `C`
+    //~| NOTE ambiguous associated type `Color`
     //~| NOTE could derive from `Vehicle`
     //~| NOTE could derive from `Box`
 }