Don't mention FromResidual on bad ?
#137232
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Unless `try_trait_v2` is enabled, don't mention that `FromResidual` isn't implemented for a specific type when the implicit `From` conversion of a `?` fails. For the end user on stable, `?` might as well be a compiler intrinsic, so we remove that note to avoid further confusion and allowing other parts of the error to be more prominent.
```
error[E0277]: `?` couldn't convert the error to `u8`
--> $DIR/bad-interconversion.rs:4:20
|
LL | fn result_to_result() -> Result<u64, u8> {
| --------------- expected `u8` because of this
LL | Ok(Err(123_i32)?)
| ------------^ the trait `From<i32>` is not implemented for `u8`
| |
| this can't be annotated with `?` because it has type `Result<_, i32>`
|
= note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
= help: the following other types implement trait `From<T>`:
`u8` implements `From<Char>`
`u8` implements `From<bool>`
```
|
rustbot has assigned @petrochenkov. Use |
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estebank
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Feb 18, 2025
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| if tcx.is_diagnostic_item(sym::FromResidual, parent_def_id) | ||
| && !tcx.features().enabled(sym::try_trait_v2) |
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We could add a further check for whether the current compiler is nightly and the feature is disabled to still provide a note that the feature could be enabled.
|
@bors r+ |
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#127793 (Added project-specific Zed IDE settings) - rust-lang#134995 (Stabilize const_slice_flatten) - rust-lang#136301 (Improve instant docs) - rust-lang#136347 (Add a bullet point to `std::fs::copy`) - rust-lang#136794 (Stabilize file_lock) - rust-lang#137094 (x86_win64 ABI: do not use xmm0 with softfloat ABI) - rust-lang#137227 (docs(dev): Update the feature-gate instructions) - rust-lang#137232 (Don't mention `FromResidual` on bad `?`) - rust-lang#137251 (coverage: Get hole spans from nested items without fully visiting them) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#137232 - estebank:from-residual-note, r=petrochenkov Don't mention `FromResidual` on bad `?` Unless `try_trait_v2` is enabled, don't mention that `FromResidual` isn't implemented for a specific type when the implicit `From` conversion of a `?` fails. For the end user on stable, `?` might as well be a compiler intrinsic, so we remove that note to avoid further confusion and allowing other parts of the error to be more prominent. ``` error[E0277]: `?` couldn't convert the error to `u8` --> $DIR/bad-interconversion.rs:4:20 | LL | fn result_to_result() -> Result<u64, u8> { | --------------- expected `u8` because of this LL | Ok(Err(123_i32)?) | ------------^ the trait `From<i32>` is not implemented for `u8` | | | this can't be annotated with `?` because it has type `Result<_, i32>` | = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait = help: the following other types implement trait `From<T>`: `u8` implements `From<Char>` `u8` implements `From<bool>` ```
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Feb 22, 2025
…li-obk
Tweak E0277 when predicate comes indirectly from ?
When a `?` operation requires an `Into` conversion with additional bounds (like having a concrete error but wanting to convert to a trait object), we handle it speficically and provide the same kind of information we give other `?` related errors.
```
error[E0277]: `?` couldn't convert the error: `E: std::error::Error` is not satisfied
--> $DIR/bad-question-mark-on-trait-object.rs:7:13
|
LL | fn foo() -> Result<(), Box<dyn std::error::Error>> {
| -------------------------------------- required `E: std::error::Error` because of this
LL | Ok(bar()?)
| -----^ the trait `std::error::Error` is not implemented for `E`
| |
| this has type `Result<_, E>`
|
note: `E` needs to implement `std::error::Error`
--> $DIR/bad-question-mark-on-trait-object.rs:1:1
|
LL | struct E;
| ^^^^^^^^
= note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
= note: required for `Box<dyn std::error::Error>` to implement `From<E>`
```
Avoid talking about `FromResidual` when other more relevant information is being given, particularly from `rust_on_unimplemented`.
Fix rust-lang#137238.
-----
CC rust-lang#137232, which was a smaller step related to this.
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Rollup merge of rust-lang#137245 - estebank:from-residual-note-2, r=oli-obk Tweak E0277 when predicate comes indirectly from ? When a `?` operation requires an `Into` conversion with additional bounds (like having a concrete error but wanting to convert to a trait object), we handle it speficically and provide the same kind of information we give other `?` related errors. ``` error[E0277]: `?` couldn't convert the error: `E: std::error::Error` is not satisfied --> $DIR/bad-question-mark-on-trait-object.rs:7:13 | LL | fn foo() -> Result<(), Box<dyn std::error::Error>> { | -------------------------------------- required `E: std::error::Error` because of this LL | Ok(bar()?) | -----^ the trait `std::error::Error` is not implemented for `E` | | | this has type `Result<_, E>` | note: `E` needs to implement `std::error::Error` --> $DIR/bad-question-mark-on-trait-object.rs:1:1 | LL | struct E; | ^^^^^^^^ = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait = note: required for `Box<dyn std::error::Error>` to implement `From<E>` ``` Avoid talking about `FromResidual` when other more relevant information is being given, particularly from `rust_on_unimplemented`. Fix rust-lang#137238. ----- CC rust-lang#137232, which was a smaller step related to this.
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Unless
try_trait_v2is enabled, don't mention thatFromResidualisn't implemented for a specific type when the implicitFromconversion of a?fails. For the end user on stable,?might as well be a compiler intrinsic, so we remove that note to avoid further confusion and allowing other parts of the error to be more prominent.