bjoernager/rust
bjoernager/rust
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Remove detail from label/note that is already available in other note

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Remove the "which is required by `{root_obligation}`" post-script in
"the trait `X` is not implemented for `Y`" explanation in E0277. This
information is already conveyed in the notes explaining requirements,
making it redundant while making the text (particularly in labels)
harder to read.

```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
  --> $DIR/wf-static-type.rs:10:13
   |
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
   |             ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`
   |
   = note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
  --> $DIR/wf-static-type.rs:7:17
   |
LL | struct IsCopy<T:Copy> { t: T }
   |                 ^^^^ required by this bound in `IsCopy`
```
vs the prior

```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
  --> $DIR/wf-static-type.rs:10:13
   |
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
   |             ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`, which is required by `Option<NotCopy>: Copy`
   |
   = note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
  --> $DIR/wf-static-type.rs:7:17
   |
LL | struct IsCopy<T:Copy> { t: T }
   |                 ^^^^ required by this bound in `IsCopy`
```
This commit is contained in:
Esteban Küber 2024-10-24 21:14:17 +00:00
parent 2dece5bb62
commit 5b54286640
223 changed files with 407 additions and 418 deletions
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15
compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
View file

@ -5105,24 +5105,13 @@ pub(super) fn get_explanation_based_on_obligation<'tcx>(
_ => None,
};
let pred = obligation.predicate;
let (_, base) = obligation.cause.code().peel_derives_with_predicate();
let post = if let ty::PredicateKind::Clause(clause) = pred.kind().skip_binder()
&& let ty::ClauseKind::Trait(pred) = clause
&& let Some(base) = base
&& base.skip_binder() != pred
{
format!(", which is required by `{base}`")
} else {
String::new()
};
let desc = match ty_desc {
Some(desc) => format!(" {desc}"),
None => String::new(),
};
if let ty::PredicatePolarity::Positive = trait_predicate.polarity() {
format!(
"{pre_message}the trait `{}` is not implemented for{desc} `{}`{post}",
"{pre_message}the trait `{}` is not implemented for{desc} `{}`",
trait_predicate.print_modifiers_and_trait_path(),
tcx.short_ty_string(trait_predicate.self_ty().skip_binder(), &mut None),
)
@ -5130,7 +5119,7 @@ pub(super) fn get_explanation_based_on_obligation<'tcx>(
// "the trait bound `T: !Send` is not satisfied" reads better than "`!Send` is
// not implemented for `T`".
// FIXME: add note explaining explicit negative trait bounds.
format!("{pre_message}the trait bound `{trait_predicate}` is not satisfied{post}")
format!("{pre_message}the trait bound `{trait_predicate}` is not satisfied")
}
}
}