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Point out region bound mismatches in check_region_bounds_on_impl_item

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This commit is contained in:
Michael Goulet
2025-04-30 15:38:24 +00:00
parent 3ef8e64ce9
commit b27d630f89
4 changed files with 79 additions and 45 deletions
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107
compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
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@@ -1137,65 +1137,88 @@ fn check_region_bounds_on_impl_item<'tcx>(
// but found 0" it's confusing, because it looks like there
// are zero. Since I don't quite know how to phrase things at
// the moment, give a kind of vague error message.
if trait_params != impl_params {
let span = tcx
.hir_get_generics(impl_m.def_id.expect_local())
.expect("expected impl item to have generics or else we can't compare them")
.span;
if trait_params == impl_params {
return Ok(());
}
let mut generics_span = None;
let mut bounds_span = vec![];
let mut where_span = None;
if let Some(trait_node) = tcx.hir_get_if_local(trait_m.def_id)
&& let Some(trait_generics) = trait_node.generics()
{
generics_span = Some(trait_generics.span);
// FIXME: we could potentially look at the impl's bounds to not point at bounds that
// *are* present in the impl.
for p in trait_generics.predicates {
if let hir::WherePredicateKind::BoundPredicate(pred) = p.kind {
for b in pred.bounds {
let span = tcx
.hir_get_generics(impl_m.def_id.expect_local())
.expect("expected impl item to have generics or else we can't compare them")
.span;
let mut generics_span = None;
let mut bounds_span = vec![];
let mut where_span = None;
if let Some(trait_node) = tcx.hir_get_if_local(trait_m.def_id)
&& let Some(trait_generics) = trait_node.generics()
{
generics_span = Some(trait_generics.span);
// FIXME: we could potentially look at the impl's bounds to not point at bounds that
// *are* present in the impl.
for p in trait_generics.predicates {
match p.kind {
hir::WherePredicateKind::BoundPredicate(hir::WhereBoundPredicate {
bounds,
..
})
| hir::WherePredicateKind::RegionPredicate(hir::WhereRegionPredicate {
bounds,
..
}) => {
for b in *bounds {
if let hir::GenericBound::Outlives(lt) = b {
bounds_span.push(lt.ident.span);
}
}
}
_ => {}
}
if let Some(impl_node) = tcx.hir_get_if_local(impl_m.def_id)
&& let Some(impl_generics) = impl_node.generics()
{
let mut impl_bounds = 0;
for p in impl_generics.predicates {
if let hir::WherePredicateKind::BoundPredicate(pred) = p.kind {
for b in pred.bounds {
}
if let Some(impl_node) = tcx.hir_get_if_local(impl_m.def_id)
&& let Some(impl_generics) = impl_node.generics()
{
let mut impl_bounds = 0;
for p in impl_generics.predicates {
match p.kind {
hir::WherePredicateKind::BoundPredicate(hir::WhereBoundPredicate {
bounds,
..
})
| hir::WherePredicateKind::RegionPredicate(hir::WhereRegionPredicate {
bounds,
..
}) => {
for b in *bounds {
if let hir::GenericBound::Outlives(_) = b {
impl_bounds += 1;
}
}
}
}
if impl_bounds == bounds_span.len() {
bounds_span = vec![];
} else if impl_generics.has_where_clause_predicates {
where_span = Some(impl_generics.where_clause_span);
_ => {}
}
}
if impl_bounds == bounds_span.len() {
bounds_span = vec![];
} else if impl_generics.has_where_clause_predicates {
where_span = Some(impl_generics.where_clause_span);
}
}
let reported = tcx
.dcx()
.create_err(LifetimesOrBoundsMismatchOnTrait {
span,
item_kind: impl_m.descr(),
ident: impl_m.ident(tcx),
generics_span,
bounds_span,
where_span,
})
.emit_unless(delay);
return Err(reported);
}
Ok(())
let reported = tcx
.dcx()
.create_err(LifetimesOrBoundsMismatchOnTrait {
span,
item_kind: impl_m.descr(),
ident: impl_m.ident(tcx),
generics_span,
bounds_span,
where_span,
})
.emit_unless(delay);
Err(reported)
}
#[instrument(level = "debug", skip(infcx))]