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Allow to self reference associated types in where clauses

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Santiago Pastorino 2020-11-13 14:01:16 -03:00
parent 24dcf6f7a2
commit 2ca4964db5
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GPG key ID: 8131A24E0C79EFAF
8 changed files with 205 additions and 64 deletions
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35
compiler/rustc_infer/src/traits/util.rs
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@ -4,6 +4,7 @@ use crate::traits::{Obligation, ObligationCause, PredicateObligation};
use rustc_data_structures::fx::FxHashSet;
use rustc_middle::ty::outlives::Component;
use rustc_middle::ty::{self, ToPredicate, TyCtxt, WithConstness};
use rustc_span::symbol::Ident;
pub fn anonymize_predicate<'tcx>(
tcx: TyCtxt<'tcx>,
@ -89,6 +90,32 @@ pub fn elaborate_trait_refs<'tcx>(
elaborate_predicates(tcx, predicates)
}
pub fn elaborate_trait_refs_that_define_assoc_type<'tcx>(
tcx: TyCtxt<'tcx>,
trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
assoc_name: Ident,
) -> FxHashSet<ty::PolyTraitRef<'tcx>> {
let mut stack: Vec<_> = trait_refs.collect();
let mut trait_refs = FxHashSet::default();
while let Some(trait_ref) = stack.pop() {
if trait_refs.insert(trait_ref) {
let super_predicates =
tcx.super_predicates_that_define_assoc_type((trait_ref.def_id(), Some(assoc_name)));
for (super_predicate, _) in super_predicates.predicates {
let bound_predicate = super_predicate.bound_atom();
let subst_predicate = super_predicate
.subst_supertrait(tcx, &bound_predicate.rebind(trait_ref.skip_binder()));
if let Some(binder) = subst_predicate.to_opt_poly_trait_ref() {
stack.push(binder.value);
}
}
}
}
trait_refs
}
pub fn elaborate_predicates<'tcx>(
tcx: TyCtxt<'tcx>,
predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
@ -287,6 +314,14 @@ pub fn transitive_bounds<'tcx>(
elaborate_trait_refs(tcx, bounds).filter_to_traits()
}
pub fn transitive_bounds_that_define_assoc_type<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
assoc_name: Ident,
) -> FxHashSet<ty::PolyTraitRef<'tcx>> {
elaborate_trait_refs_that_define_assoc_type(tcx, bounds, assoc_name)
}
///////////////////////////////////////////////////////////////////////////
// Other
///////////////////////////////////////////////////////////////////////////