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Eagerly instantiate opaque types

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This commit is contained in:
Oli Scherer 2021-12-16 15:26:01 +00:00
parent 689a868a1f
commit 5c46002273
1 changed files with 4 additions and 6 deletions
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10
compiler/rustc_infer/src/infer/opaque_types.rs
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@ -551,14 +551,16 @@ impl<'a, 'tcx> Instantiator<'a, 'tcx> {
let predicate = predicate.subst(tcx, substs); let predicate = predicate.subst(tcx, substs);
debug!(?predicate); debug!(?predicate);
// Replace all other mentions of the same opaque type with the hidden type,
// as the bounds must hold on the hidden type after all.
let predicate = predicate.fold_with(&mut BottomUpFolder { let predicate = predicate.fold_with(&mut BottomUpFolder {
tcx, tcx,
ty_op: |ty| match *ty.kind() { ty_op: |ty| match *ty.kind() {
// Replace all other mentions of the same opaque type with the hidden type,
// as the bounds must hold on the hidden type after all.
ty::Opaque(def_id2, substs2) if def_id == def_id2 && substs == substs2 => { ty::Opaque(def_id2, substs2) if def_id == def_id2 && substs == substs2 => {
ty_var ty_var
} }
// Instantiate nested instances of `impl Trait`.
ty::Opaque(..) => self.instantiate_opaque_types_in_map(ty),
_ => ty, _ => ty,
}, },
lt_op: |lt| lt, lt_op: |lt| lt,
@ -589,10 +591,6 @@ impl<'a, 'tcx> Instantiator<'a, 'tcx> {
return tcx.ty_error(); return tcx.ty_error();
} }
} }
// Change the predicate to refer to the type variable,
// which will be the concrete type instead of the opaque type.
// This also instantiates nested instances of `impl Trait`.
let predicate = self.instantiate_opaque_types_in_map(predicate);
let cause = let cause =
traits::ObligationCause::new(self.value_span, self.body_id, traits::OpaqueType); traits::ObligationCause::new(self.value_span, self.body_id, traits::OpaqueType);