Suggest bounds in more cases, accounting for type parameters referenced in predicate #144801
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r? @spastorino rustbot has assigned @spastorino. Use |
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Mind to put a link for an issue into the test? So it will be easier to follow it later (wheter for someone or while possible future test reorganization process) |
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@bors r+ rollup |
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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> {
| +++++++++++++++++++++++++++++++++++++++++++++++++
```
Fix rust-lang#144734.
matthiaskrgr
added a commit
to matthiaskrgr/rust
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Sep 6, 2025
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> {
| +++++++++++++++++++++++++++++++++++++++++++++++++
```
Fix rust-lang#144734.
bors
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Sep 6, 2025
Rollup of 3 pull requests Successful merges: - #127316 (move pinned version from tracing_core to tracing) - #144801 (Suggest bounds in more cases, accounting for type parameters referenced in predicate) - #146211 (Disallow shebang in `--cfg` and `--check-cfg` arguments) r? `@ghost` `@rustbot` modify labels: rollup
bors
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Sep 6, 2025
Rollup of 5 pull requests Successful merges: - #127316 (move pinned version from tracing_core to tracing) - #144801 (Suggest bounds in more cases, accounting for type parameters referenced in predicate) - #146211 (Disallow shebang in `--cfg` and `--check-cfg` arguments) - #146263 (Fix `bump-stage0` build failure, and check-build `bump-stage0` in CI) - #146266 (miri std tests: skip all of sys::) r? `@ghost` `@rustbot` modify labels: rollup
rust-timer
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Rollup merge of #144801 - estebank:issue-144734, r=spastorino 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> { | +++++++++++++++++++++++++++++++++++++++++++++++++ ``` Fix #144734.
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Use a
ty::Visitorto 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:
Fix #144734.