bjoernager/rust
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Do binder folding eagerly in bound_coroutine_hidden_types

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I refuse to fix this in the old solver; its lazy instantiation of
binders will be the end of me.
This commit is contained in:
Michael Goulet 2024-03-14 11:51:22 -04:00
parent 67f1c53c05
commit bca708b9fa
3 changed files with 42 additions and 37 deletions
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36
compiler/rustc_middle/src/ty/util.rs
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@ -682,6 +682,9 @@ impl<'tcx> TyCtxt<'tcx> {
/// Return the set of types that should be taken into account when checking
/// trait bounds on a coroutine's internal state.
// FIXME(compiler-errors): We should remove this when the old solver goes away;
// and all other usages of this function should go through `bound_coroutine_hidden_types`
// instead.
pub fn coroutine_hidden_types(
self,
def_id: DefId,
@ -694,6 +697,33 @@ impl<'tcx> TyCtxt<'tcx> {
.map(|decl| ty::EarlyBinder::bind(decl.ty))
}
/// Return the set of types that should be taken into account when checking
/// trait bounds on a coroutine's internal state. This properly replaces
/// `ReErased` with new existential bound lifetimes.
pub fn bound_coroutine_hidden_types(
self,
def_id: DefId,
) -> impl Iterator<Item = ty::EarlyBinder<ty::Binder<'tcx, Ty<'tcx>>>> {
let coroutine_layout = self.mir_coroutine_witnesses(def_id);
coroutine_layout
.as_ref()
.map_or_else(|| [].iter(), |l| l.field_tys.iter())
.filter(|decl| !decl.ignore_for_traits)
.map(move |decl| {
let mut vars = vec![];
let ty = self.fold_regions(decl.ty, |re, debruijn| {
assert_eq!(re, self.lifetimes.re_erased);
let var = ty::BoundVar::from_usize(vars.len());
vars.push(ty::BoundVariableKind::Region(ty::BrAnon));
ty::Region::new_bound(self, debruijn, ty::BoundRegion { var, kind: ty::BrAnon })
});
ty::EarlyBinder::bind(ty::Binder::bind_with_vars(
ty,
self.mk_bound_variable_kinds(&vars),
))
})
}
/// Expands the given impl trait type, stopping if the type is recursive.
#[instrument(skip(self), level = "debug", ret)]
pub fn try_expand_impl_trait_type(
@ -998,8 +1028,10 @@ impl<'tcx> OpaqueTypeExpander<'tcx> {
Some(expanded_ty) => *expanded_ty,
None => {
if matches!(self.inspect_coroutine_fields, InspectCoroutineFields::Yes) {
for bty in self.tcx.coroutine_hidden_types(def_id) {
let hidden_ty = bty.instantiate(self.tcx, args);
for bty in self.tcx.bound_coroutine_hidden_types(def_id) {
let hidden_ty = self.tcx.instantiate_bound_regions_with_erased(
bty.instantiate(self.tcx, args),
);
self.fold_ty(hidden_ty);
}
}