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Properly account for binders in get_impl_future_output_ty

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This commit is contained in:
Tyler Mandry 2021-12-21 22:08:47 +00:00
parent 5e57faa78a
commit 6487845884
4 changed files with 31 additions and 20 deletions
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29
compiler/rustc_infer/src/infer/error_reporting/mod.rs
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@ -69,7 +69,7 @@ use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::{
self,
subst::{GenericArgKind, Subst, SubstsRef},
Region, Ty, TyCtxt, TypeFoldable,
Binder, Region, Ty, TyCtxt, TypeFoldable,
};
use rustc_span::{sym, BytePos, DesugaringKind, MultiSpan, Pos, Span};
use rustc_target::spec::abi;
@ -1765,7 +1765,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
self.note_error_origin(diag, cause, exp_found, terr);
}
pub fn get_impl_future_output_ty(&self, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
pub fn get_impl_future_output_ty(&self, ty: Ty<'tcx>) -> Option<Binder<'tcx, Ty<'tcx>>> {
if let ty::Opaque(def_id, substs) = ty.kind() {
let future_trait = self.tcx.require_lang_item(LangItem::Future, None);
// Future::Output
@ -1775,13 +1775,20 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
for (predicate, _) in bounds {
let predicate = predicate.subst(self.tcx, substs);
if let ty::PredicateKind::Projection(projection_predicate) =
predicate.kind().skip_binder()
{
if projection_predicate.projection_ty.item_def_id == item_def_id {
// We don't account for multiple `Future::Output = Ty` contraints.
return projection_predicate.term.ty();
}
let output = predicate
.kind()
.map_bound(|kind| match kind {
ty::PredicateKind::Projection(projection_predicate)
if projection_predicate.projection_ty.item_def_id == item_def_id =>
{
projection_predicate.term.ty()
}
_ => None,
})
.transpose();
if output.is_some() {
// We don't account for multiple `Future::Output = Ty` contraints.
return output;
}
}
}
@ -1823,8 +1830,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
}
match (
self.get_impl_future_output_ty(exp_found.expected),
self.get_impl_future_output_ty(exp_found.found),
self.get_impl_future_output_ty(exp_found.expected).map(Binder::skip_binder),
self.get_impl_future_output_ty(exp_found.found).map(Binder::skip_binder),
) {
(Some(exp), Some(found)) if same_type_modulo_infer(exp, found) => match cause.code() {
ObligationCauseCode::IfExpression(box IfExpressionCause { then, .. }) => {