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Suggest copying trait associated type bounds on lifetime error

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This commit is contained in:
Jack Huey 2022-01-08 23:30:19 -05:00
parent 30b3f35c42
commit 3d19c8defd
12 changed files with 163 additions and 28 deletions
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2
compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs
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@ -64,7 +64,7 @@ impl<'cx, 'tcx> NiceRegionError<'cx, 'tcx> {
.or_else(|| self.try_report_mismatched_static_lifetime())
}
pub fn regions(&self) -> Option<(Span, ty::Region<'tcx>, ty::Region<'tcx>)> {
pub(super) fn regions(&self) -> Option<(Span, ty::Region<'tcx>, ty::Region<'tcx>)> {
match (&self.error, self.regions) {
(Some(ConcreteFailure(origin, sub, sup)), None) => Some((origin.span(), *sub, *sup)),
(Some(SubSupConflict(_, _, origin, sub, _, sup, _)), None) => {

52
compiler/rustc_infer/src/infer/error_reporting/note.rs
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@ -102,6 +102,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
"...so that the definition in impl matches the definition from the trait",
);
}
infer::CheckAssociatedTypeBounds { ref parent, .. } => {
self.note_region_origin(err, &parent);
}
}
}
@ -345,6 +348,55 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
trait_item_def_id,
&format!("`{}: {}`", sup, sub),
),
infer::CheckAssociatedTypeBounds { impl_item_def_id, trait_item_def_id, parent } => {
let mut err = self.report_concrete_failure(*parent, sub, sup);
let trait_item_span = self.tcx.def_span(trait_item_def_id);
let item_name = self.tcx.item_name(impl_item_def_id);
err.span_label(
trait_item_span,
format!("definition of `{}` from trait", item_name),
);
let trait_predicates = self.tcx.explicit_predicates_of(trait_item_def_id);
let impl_predicates = self.tcx.explicit_predicates_of(impl_item_def_id);
let impl_predicates: rustc_data_structures::stable_set::FxHashSet<_> =
impl_predicates.predicates.into_iter().map(|(pred, _)| pred).collect();
let clauses: Vec<_> = trait_predicates
.predicates
.into_iter()
.filter(|&(pred, _)| !impl_predicates.contains(pred))
.map(|(pred, _)| format!("{}", pred))
.collect();
if !clauses.is_empty() {
let where_clause_span = self
.tcx
.hir()
.get_generics(impl_item_def_id.expect_local())
.unwrap()
.where_clause
.tail_span_for_suggestion();
let suggestion = format!(
"{} {}",
if !impl_predicates.is_empty() { "," } else { " where" },
clauses.join(", "),
);
err.span_suggestion(
where_clause_span,
&format!(
"try copying {} from the trait",
if clauses.len() > 1 { "these clauses" } else { "this clause" }
),
suggestion,
rustc_errors::Applicability::MaybeIncorrect,
);
}
err
}
}
}

17
compiler/rustc_infer/src/infer/mod.rs
View File

@ -438,6 +438,13 @@ pub enum SubregionOrigin<'tcx> {
/// Comparing the signature and requirements of an impl associated type
/// against the containing trait
CompareImplTypeObligation { span: Span, impl_item_def_id: DefId, trait_item_def_id: DefId },
/// Checking that the bounds of a trait's associated type hold for a given impl
CheckAssociatedTypeBounds {
parent: Box<SubregionOrigin<'tcx>>,
impl_item_def_id: DefId,
trait_item_def_id: DefId,
},
}
// `SubregionOrigin` is used a lot. Make sure it doesn't unintentionally get bigger.
@ -1832,6 +1839,7 @@ impl<'tcx> SubregionOrigin<'tcx> {
ReferenceOutlivesReferent(_, a) => a,
CompareImplMethodObligation { span, .. } => span,
CompareImplTypeObligation { span, .. } => span,
CheckAssociatedTypeBounds { ref parent, .. } => parent.span(),
}
}
@ -1862,6 +1870,15 @@ impl<'tcx> SubregionOrigin<'tcx> {
trait_item_def_id,
},
traits::ObligationCauseCode::CheckAssociatedTypeBounds {
impl_item_def_id,
trait_item_def_id,
} => SubregionOrigin::CheckAssociatedTypeBounds {
impl_item_def_id,
trait_item_def_id,
parent: Box::new(default()),
},
_ => default(),
}
}

6
compiler/rustc_middle/src/traits/mod.rs
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@ -285,6 +285,12 @@ pub enum ObligationCauseCode<'tcx> {
trait_item_def_id: DefId,
},
/// Checking that the bounds of a trait's associated type hold for a given impl
CheckAssociatedTypeBounds {
impl_item_def_id: DefId,
trait_item_def_id: DefId,
},
/// Checking that this expression can be assigned where it needs to be
// FIXME(eddyb) #11161 is the original Expr required?
ExprAssignable,

3
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
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@ -1932,7 +1932,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
| ObligationCauseCode::AwaitableExpr(_)
| ObligationCauseCode::ForLoopIterator
| ObligationCauseCode::QuestionMark
| ObligationCauseCode::LetElse => {}
| ObligationCauseCode::LetElse
| ObligationCauseCode::CheckAssociatedTypeBounds { .. } => {}
ObligationCauseCode::SliceOrArrayElem => {
err.note("slice and array elements must have `Sized` type");
}

9
compiler/rustc_typeck/src/check/compare_method.rs
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@ -1378,7 +1378,14 @@ pub fn check_type_bounds<'tcx>(
let mut selcx = traits::SelectionContext::new(&infcx);
let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local());
let normalize_cause = traits::ObligationCause::misc(impl_ty_span, impl_ty_hir_id);
let normalize_cause = ObligationCause::new(
impl_ty_span,
impl_ty_hir_id,
ObligationCauseCode::CheckAssociatedTypeBounds {
impl_item_def_id: impl_ty.def_id,
trait_item_def_id: trait_ty.def_id,
},
);
let mk_cause = |span: Span| {
let code = if span.is_dummy() {
traits::MiscObligation

7
src/test/ui/generic-associated-types/impl_bounds.stderr
View File

@ -19,8 +19,13 @@ LL | type B<'a, 'b> where 'b: 'a = (&'a(), &'b ());
error[E0478]: lifetime bound not satisfied
--> $DIR/impl_bounds.rs:17:35
|
LL | type B<'a, 'b> where 'a: 'b;
| ---------------------------- definition of `B` from trait
...
LL | type B<'a, 'b> where 'b: 'a = (&'a(), &'b ());
| ^^^^^^^^^^^^^^^
| - ^^^^^^^^^^^^^^^
| |
| help: try copying this clause from the trait: `, 'a: 'b`
|
note: lifetime parameter instantiated with the lifetime `'a` as defined here
--> $DIR/impl_bounds.rs:17:12

5
src/test/ui/generic-associated-types/issue-88595.rs
View File

@ -8,7 +8,7 @@ trait A<'a> {
// FIXME(generic_associated_types): Remove one of the below bounds
// https://github.com/rust-lang/rust/pull/90678#discussion_r744976085
where
'a: 'b, Self: 'a, Self: 'b;
Self: 'a, Self: 'b;
fn a(&'a self) -> Self::B<'a>;
}
@ -17,8 +17,7 @@ struct C;
impl<'a> A<'a> for C {
type B<'b> = impl Clone;
//~^ ERROR: lifetime bound not satisfied
//~| ERROR: could not find defining uses
//~^ ERROR: could not find defining uses
fn a(&'a self) -> Self::B<'a> {} //~ ERROR: non-defining opaque type use in defining scope
}

22
src/test/ui/generic-associated-types/issue-88595.stderr
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@ -1,22 +1,5 @@
error[E0478]: lifetime bound not satisfied
--> $DIR/issue-88595.rs:19:18
|
LL | type B<'b> = impl Clone;
| ^^^^^^^^^^
|
note: lifetime parameter instantiated with the lifetime `'a` as defined here
--> $DIR/issue-88595.rs:18:6
|
LL | impl<'a> A<'a> for C {
| ^^
note: but lifetime parameter must outlive the lifetime `'b` as defined here
--> $DIR/issue-88595.rs:19:12
|
LL | type B<'b> = impl Clone;
| ^^
error: non-defining opaque type use in defining scope
--> $DIR/issue-88595.rs:23:23
--> $DIR/issue-88595.rs:22:23
|
LL | fn a(&'a self) -> Self::B<'a> {}
| ^^^^^^^^^^^
@ -35,6 +18,5 @@ error: could not find defining uses
LL | type B<'b> = impl Clone;
| ^^^^^^^^^^
error: aborting due to 3 previous errors
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0478`.

7
src/test/ui/generic-associated-types/issue-90014.stderr
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@ -1,8 +1,13 @@
error[E0477]: the type `&mut ()` does not fulfill the required lifetime
--> $DIR/issue-90014.rs:14:20
|
LL | type Fut<'a> where Self: 'a;
| ---------------------------- definition of `Fut` from trait
...
LL | type Fut<'a> = impl Future<Output = ()>;
| ^^^^^^^^^^^^^^^^^^^^^^^^
| - ^^^^^^^^^^^^^^^^^^^^^^^^
| |
| help: try copying this clause from the trait: `where Self: 'a`
|
note: type must outlive the lifetime `'a` as defined here
--> $DIR/issue-90014.rs:14:14

39
src/test/ui/generic-associated-types/issue-92033.rs Normal file
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@ -0,0 +1,39 @@
#![feature(generic_associated_types)]
struct Texture;
trait Surface {
type TextureIter<'a>: Iterator<Item = &'a Texture>
where
Self: 'a;
fn get_texture(&self) -> Self::TextureIter<'_>;
}
trait Swapchain {
type Surface<'a>: Surface
where
Self: 'a;
fn get_surface(&self) -> Self::Surface<'_>;
}
impl<'s> Surface for &'s Texture {
type TextureIter<'a> = std::option::IntoIter<&'a Texture>;
//~^ ERROR the type
fn get_texture(&self) -> Self::TextureIter<'_> {
let option: Option<&Texture> = Some(self);
option.into_iter()
}
}
impl Swapchain for Texture {
type Surface<'a> = &'a Texture;
fn get_surface(&self) -> Self::Surface<'_> {
self
}
}
fn main() {}

22
src/test/ui/generic-associated-types/issue-92033.stderr Normal file
View File

@ -0,0 +1,22 @@
error[E0477]: the type `&'s Texture` does not fulfill the required lifetime
--> $DIR/issue-92033.rs:22:28
|
LL | / type TextureIter<'a>: Iterator<Item = &'a Texture>
LL | | where
LL | | Self: 'a;
| |_________________- definition of `TextureIter` from trait
...
LL | type TextureIter<'a> = std::option::IntoIter<&'a Texture>;
| - ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| help: try copying this clause from the trait: `where Self: 'a`
|
note: type must outlive the lifetime `'a` as defined here
--> $DIR/issue-92033.rs:22:22
|
LL | type TextureIter<'a> = std::option::IntoIter<&'a Texture>;
| ^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0477`.