Suggest bounds in more cases, accounting for type parameters referenced in predicate
Use a `ty::Visitor` to see if the failed predicate references a type parameter. If it does, then we only suggest adding a bound to an (associated) item only if the referenced parameter is present in its generics.
Provide adding bound suggestion in trait and impl associated functions in cases we previously weren't:
```
error[E0277]: `?` couldn't convert the error to `ApplicationError`
--> $DIR/suggest-complex-bound-on-method.rs:18:16
|
LL | t.run()?;
| -----^ the trait `From<<T as Trait>::Error>` is not implemented for `ApplicationError`
| |
| this can't be annotated with `?` because it has type `Result<_, <T as Trait>::Error>`
|
note: `ApplicationError` needs to implement `From<<T as Trait>::Error>`
--> $DIR/suggest-complex-bound-on-method.rs:12:1
|
LL | enum ApplicationError {
| ^^^^^^^^^^^^^^^^^^^^^
= note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
|
LL | fn thing<T: Trait>(&self, t: T) -> Result<(), ApplicationError> where ApplicationError: From<<T as Trait>::Error> {
| +++++++++++++++++++++++++++++++++++++++++++++++++
```
Fixrust-lang/rust#144734.
bc0dfaa048