Bonus format for E0194

[leikahing]

Bonus fix for #35280. Part of #35233. Fixes #36057. Adding expanded notes/context for what trait a parameter shadows as part of E0194 error messages.

Errors for E0194 now look like this:

$> ./build/x86_64-apple-darwin/stage1/bin/rustc src/test/compile-fail/E0194.rs 
error[E0194]: type parameter `T` shadows another type parameter of the same name
  --> src/test/compile-fail/E0194.rs:13:26
   |
11 | trait Foo<T> { //~ NOTE first `T` declared here
   |           - first `T` declared here
12 |     fn do_something(&self) -> T;
13 |     fn do_something_else<T: Clone>(&self, bar: T);
   |                          ^ shadows another type parameter

error: aborting due to previous error

r? @jonathandturner

[sophiajt]

@birryree - I'm going to also go on the assumption that the unwraps are okay because the type parameter is local. I tried for a few minutes to come up with a counter example but wasn't able to.

@bors r+ rollup

[bors]

📌 Commit fb38911 has been approved by jonathandturner

[leikahing]

@jonathandturner - I've been looking at the well-formed checker heavily and I based it on what I know about Rust currently and what @nikomatsakis mentioned to me as part of #35280. I took this bonus to a separate issue so I could get a review of the unwrap portion, just in case my assumptions were wrong. Thanks for looking and affirming!

[nikomatsakis]

Yes, I think the unwraps are ok. :)

[sophiajt]

@bors r+

[bors]

📌 Commit 69f0cee has been approved by jonathandturner

[leikahing]

@jonathandturner Sorry to give you some extra work, but I just updated my PR to cut down a line that was 101 characters long and broke tidy. Forgot to run the tidy check before my initial commit, sorry. :(