E0221 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0221.rs

Error E0221 needs a span_label, updating it from:

error[E0221]: ambiguous associated type `A` in bounds of `Self`
  --> src/test/compile-fail/E0221.rs:21:16
   |
21 |         let _: Self::A; //~ ERROR E0221
   |                ^^^^^^^
   |
note: associated type `Self` could derive from `Foo`
  --> src/test/compile-fail/E0221.rs:21:16
   |
21 |         let _: Self::A; //~ ERROR E0221
   |                ^^^^^^^
note: associated type `Self` could derive from `Bar`
  --> src/test/compile-fail/E0221.rs:21:16
   |
21 |         let _: Self::A; //~ ERROR E0221
   |                ^^^^^^^

To:

error[E0221]: ambiguous associated type `A` in bounds of `Self`
  --> src/test/compile-fail/E0221.rs:21:16
   |
21 |         let _: Self::A; //~ ERROR E0221
   |                ^^^^^^^ ambiguous associated type `A`
   |
note: associated type `Self` could derive from `Foo`
  --> src/test/compile-fail/E0221.rs:21:16
   |
21 |         let _: Self::A; //~ ERROR E0221
   |                ^^^^^^^
note: associated type `Self` could derive from `Bar`
  --> src/test/compile-fail/E0221.rs:21:16
   |
21 |         let _: Self::A; //~ ERROR E0221
   |                ^^^^^^^

[tvladyslav]

@jonathandturner Is it expected result?

[sophiajt]

@crypto-universe - yes, that's expected. Though, as you probably suspect, it's not ideal. Would be great to know where the other possibilities are coming from.

I didn't put the bonus on here, but if you wanted to try to tackle a bonus, you could see if the information is available to see where those types are coming from.

[tvladyslav]

@jonathandturner Got the idea. I'll spend some time on this. Wait with merging, please.