bjoernager/rust
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Rework how we emit errors for unresolved object lifetimes

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This commit is contained in:
Michael Goulet 2024-08-24 14:55:31 -04:00
parent f167efad2f
commit 147bb17f51
3 changed files with 25 additions and 16 deletions
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2
compiler/rustc_hir_analysis/src/collect.rs
View file

@ -392,7 +392,7 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
} }
fn re_infer(&self, span: Span, reason: RegionInferReason<'_>) -> ty::Region<'tcx> { fn re_infer(&self, span: Span, reason: RegionInferReason<'_>) -> ty::Region<'tcx> {
if let RegionInferReason::BorrowedObjectLifetimeDefault = reason { if let RegionInferReason::ObjectLifetimeDefault = reason {
let e = struct_span_code_err!( let e = struct_span_code_err!(
self.dcx(), self.dcx(),
span, span,

7
compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
View file

@ -85,10 +85,9 @@ pub enum PredicateFilter {
#[derive(Debug)] #[derive(Debug)]
pub enum RegionInferReason<'a> { pub enum RegionInferReason<'a> {
/// Lifetime on a trait object behind a reference. /// Lifetime on a trait object that is spelled explicitly, e.g. `+ 'a` or `+ '_`.
/// This allows inferring information from the reference. ExplicitObjectLifetime,
BorrowedObjectLifetimeDefault, /// A trait object's lifetime when it is elided, e.g. `dyn Any`.
/// A trait object's lifetime.
ObjectLifetimeDefault, ObjectLifetimeDefault,
/// Generic lifetime parameter /// Generic lifetime parameter
Param(&'a ty::GenericParamDef), Param(&'a ty::GenericParamDef),

32
compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs
View file

@ -30,7 +30,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
hir_id: hir::HirId, hir_id: hir::HirId,
hir_trait_bounds: &[(hir::PolyTraitRef<'tcx>, hir::TraitBoundModifier)], hir_trait_bounds: &[(hir::PolyTraitRef<'tcx>, hir::TraitBoundModifier)],
lifetime: &hir::Lifetime, lifetime: &hir::Lifetime,
borrowed: bool, _borrowed: bool,
representation: DynKind, representation: DynKind,
) -> Ty<'tcx> { ) -> Ty<'tcx> {
let tcx = self.tcx(); let tcx = self.tcx();
@ -325,22 +325,32 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
v.dedup(); v.dedup();
let existential_predicates = tcx.mk_poly_existential_predicates(&v); let existential_predicates = tcx.mk_poly_existential_predicates(&v);
// Use explicitly-specified region bound. // Use explicitly-specified region bound, unless the bound is missing.
let region_bound = if !lifetime.is_elided() { let region_bound = if !lifetime.is_elided() {
self.lower_lifetime(lifetime, RegionInferReason::ObjectLifetimeDefault) self.lower_lifetime(lifetime, RegionInferReason::ExplicitObjectLifetime)
} else { } else {
self.compute_object_lifetime_bound(span, existential_predicates).unwrap_or_else(|| { self.compute_object_lifetime_bound(span, existential_predicates).unwrap_or_else(|| {
// Curiously, we prefer object lifetime default for `+ '_`...
if tcx.named_bound_var(lifetime.hir_id).is_some() { if tcx.named_bound_var(lifetime.hir_id).is_some() {
self.lower_lifetime(lifetime, RegionInferReason::ObjectLifetimeDefault) self.lower_lifetime(lifetime, RegionInferReason::ExplicitObjectLifetime)
} else { } else {
self.re_infer( let reason =
span, if let hir::LifetimeName::ImplicitObjectLifetimeDefault = lifetime.res {
if borrowed { if let hir::Node::Ty(hir::Ty {
RegionInferReason::ObjectLifetimeDefault kind: hir::TyKind::Ref(parent_lifetime, _),
..
}) = tcx.parent_hir_node(hir_id)
&& tcx.named_bound_var(parent_lifetime.hir_id).is_none()
{
// Parent lifetime must have failed to resolve. Don't emit a redundant error.
RegionInferReason::ExplicitObjectLifetime
} else {
RegionInferReason::ObjectLifetimeDefault
}
} else { } else {
RegionInferReason::BorrowedObjectLifetimeDefault RegionInferReason::ExplicitObjectLifetime
}, };
) self.re_infer(span, reason)
} }
}) })
}; };