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Point at explicit 'static obligations on a trait

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Given `trait Any: 'static` and a `struct` with a `Box<dyn Any + 'a>` field, point at the `'static` bound in `Any` to explain why `'a: 'static`.

```
error[E0478]: lifetime bound not satisfied
   --> f202.rs:2:12
    |
2   |     value: Box<dyn std::any::Any + 'a>,
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
note: lifetime parameter instantiated with the lifetime `'a` as defined here
   --> f202.rs:1:14
    |
1   | struct Hello<'a> {
    |              ^^
note: but lifetime parameter must outlive the static lifetime
   --> /home/gh-estebank/rust/library/core/src/any.rs:113:16
    |
113 | pub trait Any: 'static {
    |                ^^^^^^^
```

Partially address #33652.
This commit is contained in:
Esteban Küber 2024-08-12 22:57:14 +00:00
parent 4d5b3b1962
commit f5bae722be
8 changed files with 80 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
compiler/rustc_hir_analysis/src/check/wfcheck.rs
View File

@ -747,7 +747,7 @@ fn region_known_to_outlive<'tcx>(
region_b: ty::Region<'tcx>,
) -> bool {
test_region_obligations(tcx, id, param_env, wf_tys, |infcx| {
infcx.sub_regions(infer::RelateRegionParamBound(DUMMY_SP), region_b, region_a);
infcx.sub_regions(infer::RelateRegionParamBound(DUMMY_SP, None), region_b, region_a);
})
}

2
compiler/rustc_infer/src/infer/context.rs
View File

@ -167,7 +167,7 @@ fn probe<T>(&self, probe: impl FnOnce() -> T) -> T {
}
fn sub_regions(&self, sub: ty::Region<'tcx>, sup: ty::Region<'tcx>) {
self.sub_regions(SubregionOrigin::RelateRegionParamBound(DUMMY_SP), sub, sup)
self.sub_regions(SubregionOrigin::RelateRegionParamBound(DUMMY_SP, None), sub, sup)
}
fn register_ty_outlives(&self, ty: Ty<'tcx>, r: ty::Region<'tcx>) {

10
compiler/rustc_infer/src/infer/mod.rs
View File

@ -390,7 +390,7 @@ pub enum SubregionOrigin<'tcx> {
/// The given region parameter was instantiated with a region
/// that must outlive some other region.
RelateRegionParamBound(Span),
RelateRegionParamBound(Span, Option<Ty<'tcx>>),
/// Creating a pointer `b` to contents of another reference.
Reborrow(Span),
@ -859,7 +859,7 @@ pub fn region_outlives_predicate(
) {
self.enter_forall(predicate, |ty::OutlivesPredicate(r_a, r_b)| {
let origin = SubregionOrigin::from_obligation_cause(cause, || {
RelateRegionParamBound(cause.span)
RelateRegionParamBound(cause.span, None)
});
self.sub_regions(origin, r_b, r_a); // `b : a` ==> `a <= b`
})
@ -1685,7 +1685,7 @@ pub fn span(&self) -> Span {
Subtype(ref a) => a.span(),
RelateObjectBound(a) => a,
RelateParamBound(a, ..) => a,
RelateRegionParamBound(a) => a,
RelateRegionParamBound(a, _) => a,
Reborrow(a) => a,
ReferenceOutlivesReferent(_, a) => a,
CompareImplItemObligation { span, .. } => span,
@ -1726,6 +1726,10 @@ pub fn from_obligation_cause<F>(cause: &traits::ObligationCause<'tcx>, default:
SubregionOrigin::AscribeUserTypeProvePredicate(span)
}
traits::ObligationCauseCode::ObjectTypeBound(ty, _reg) => {
SubregionOrigin::RelateRegionParamBound(cause.span, Some(ty))
}
_ => default(),
}
}

2
compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/placeholder_relation.rs
View File

@ -11,7 +11,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
pub(super) fn try_report_placeholder_relation(&self) -> Option<Diag<'tcx>> {
match &self.error {
Some(RegionResolutionError::ConcreteFailure(
SubregionOrigin::RelateRegionParamBound(span),
SubregionOrigin::RelateRegionParamBound(span, _),
Region(Interned(
RePlaceholder(ty::Placeholder {
bound: ty::BoundRegion { kind: sub_name, .. },

4
compiler/rustc_trait_selection/src/error_reporting/infer/note.rs
View File

@ -52,7 +52,7 @@ pub(super) fn note_region_origin(&self, err: &mut Diag<'_>, origin: &SubregionOr
.add_to_diag(err);
}
}
infer::RelateRegionParamBound(span) => {
infer::RelateRegionParamBound(span, _) => {
RegionOriginNote::Plain { span, msg: fluent::infer_relate_region_param_bound }
.add_to_diag(err);
}
@ -199,7 +199,7 @@ pub(super) fn report_concrete_failure(
note,
})
}
infer::RelateRegionParamBound(span) => {
infer::RelateRegionParamBound(span, _) => {
let param_instantiated = note_and_explain::RegionExplanation::new(
self.tcx,
generic_param_scope,

26
compiler/rustc_trait_selection/src/error_reporting/infer/region.rs
View File

@ -257,7 +257,7 @@ pub(super) fn note_region_origin(&self, err: &mut Diag<'_>, origin: &SubregionOr
.add_to_diag(err);
}
}
infer::RelateRegionParamBound(span) => {
infer::RelateRegionParamBound(span, _) => {
RegionOriginNote::Plain {
span,
msg: fluent::trait_selection_relate_region_param_bound,
@ -410,7 +410,7 @@ pub(super) fn report_concrete_failure(
note,
})
}
infer::RelateRegionParamBound(span) => {
infer::RelateRegionParamBound(span, ty) => {
let param_instantiated = note_and_explain::RegionExplanation::new(
self.tcx,
generic_param_scope,
@ -419,11 +419,31 @@ pub(super) fn report_concrete_failure(
note_and_explain::PrefixKind::LfParamInstantiatedWith,
note_and_explain::SuffixKind::Empty,
);
let mut alt_span = None;
if let Some(ty) = ty
&& sub.is_static()
&& let ty::Dynamic(preds, _, ty::DynKind::Dyn) = ty.kind()
&& let Some(def_id) = preds.principal_def_id()
{
for (clause, span) in
self.tcx.predicates_of(def_id).instantiate_identity(self.tcx)
{
if let ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(a, b)) =
clause.kind().skip_binder()
&& let ty::Param(param) = a.kind()
&& param.name == kw::SelfUpper
&& b.is_static()
{
// Point at explicit `'static` bound on the trait (`trait T: 'static`).
alt_span = Some(span);
}
}
}
let param_must_outlive = note_and_explain::RegionExplanation::new(
self.tcx,
generic_param_scope,
sub,
None,
alt_span,
note_and_explain::PrefixKind::LfParamMustOutlive,
note_and_explain::SuffixKind::Empty,
);

13
tests/ui/regions/explicit-static-bound-on-trait.rs Normal file
View File

@ -0,0 +1,13 @@
struct Hello<'a> {
value: Box<dyn std::any::Any + 'a>,
//~^ ERROR lifetime bound not satisfied
}
impl<'a> Hello<'a> {
fn new<T: 'a>(value: T) -> Self {
Self { value: Box::new(value) }
//~^ ERROR the parameter type `T` may not live long enough
}
}
fn main() {}

32
tests/ui/regions/explicit-static-bound-on-trait.stderr Normal file
View File

@ -0,0 +1,32 @@
error[E0478]: lifetime bound not satisfied
--> $DIR/explicit-static-bound-on-trait.rs:2:12
|
LL | value: Box<dyn std::any::Any + 'a>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: lifetime parameter instantiated with the lifetime `'a` as defined here
--> $DIR/explicit-static-bound-on-trait.rs:1:14
|
LL | struct Hello<'a> {
| ^^
note: but lifetime parameter must outlive the static lifetime
--> $SRC_DIR/core/src/any.rs:LL:COL
error[E0310]: the parameter type `T` may not live long enough
--> $DIR/explicit-static-bound-on-trait.rs:8:23
|
LL | Self { value: Box::new(value) }
| ^^^^^^^^^^^^^^^
| |
| the parameter type `T` must be valid for the static lifetime...
| ...so that the type `T` will meet its required lifetime bounds
|
help: consider adding an explicit lifetime bound
|
LL | fn new<T: 'a + 'static>(value: T) -> Self {
| +++++++++
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0310, E0478.
For more information about an error, try `rustc --explain E0310`.