Rollup merge of #108254 - Nathan-Fenner:nathanf/error-span-ref-trait-refine, r=WaffleLapkin

Refine error span for trait error into borrowed expression

Extends the error span refinement in #106477 to drill into borrowed expressions just like tuples/struct/enum literals. For example,

```rs
trait Fancy {}
trait Good {}
impl <'a, T> Fancy for &'a T where T: Good {}
impl <S> Good for Option<S> where S: Iterator {}

fn want_fancy<F>(f: F) where F: Fancy {}

fn example() {
    want_fancy(&Some(5));
//  (BEFORE)   ^^^^^^^^ `{integer}` is not an iterator
//  (AFTER)          ^  `{integer}` is not an iterator
}
```

Existing heuristics try to find the right part of the expression to "point at"; current heuristics look at e.g. struct constructors and tuples. This PR adds a new check for borrowed expressions when looking into a borrowed type.

0 files changed, 0 insertions, 0 deletions