bjoernager/rust
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Make empty bounds lower to WellFormed and make WellFormed coinductive

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This commit is contained in:
Jack Huey 2022-06-26 11:08:58 -04:00
parent 8e430bfa9a
commit e16dbb5076
8 changed files with 100 additions and 26 deletions
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3
compiler/rustc_typeck/src/check/dropck.rs
View file

@ -206,6 +206,9 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
relator.relate(predicate.rebind(ty_a), p.rebind(ty_b)).is_ok()
&& relator.relate(predicate.rebind(lt_a), p.rebind(lt_b)).is_ok()
}
(ty::PredicateKind::WellFormed(arg_a), ty::PredicateKind::WellFormed(arg_b)) => {
relator.relate(predicate.rebind(arg_a), p.rebind(arg_b)).is_ok()
}
_ => predicate == p,
}
};

6
compiler/rustc_typeck/src/check/wfcheck.rs
View file

@ -1807,6 +1807,12 @@ fn check_false_global_bounds(fcx: &FnCtxt<'_, '_>, mut span: Span, id: hir::HirI
let implied_obligations = traits::elaborate_predicates_with_span(fcx.tcx, predicates_with_span);
for obligation in implied_obligations {
// We lower empty bounds like `Vec<dyn Copy>:` as
// `WellFormed(Vec<dyn Copy>)`, which will later get checked by
// regular WF checking
if let ty::PredicateKind::WellFormed(..) = obligation.predicate.kind().skip_binder() {
continue;
}
let pred = obligation.predicate;
// Match the existing behavior.
if pred.is_global() && !pred.has_late_bound_regions() {

6
compiler/rustc_typeck/src/collect.rs
View file

@ -2264,12 +2264,8 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericP
// compiler/tooling bugs from not handling WF predicates.
} else {
let span = bound_pred.bounded_ty.span;
let re_root_empty = tcx.lifetimes.re_root_empty;
let predicate = ty::Binder::bind_with_vars(
ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
ty,
re_root_empty,
)),
ty::PredicateKind::WellFormed(ty.into()),
bound_vars,
);
predicates.insert((predicate.to_predicate(tcx), span));