bjoernager/rust
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Only walk the identity substituted version of struct fields

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This commit is contained in:
Oli Scherer 2023-06-19 17:58:14 +00:00
parent b323f587fc
commit 27b386ad17
5 changed files with 126 additions and 1 deletions
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23
compiler/rustc_ty_utils/src/opaque_types.rs
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@ -82,10 +82,12 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for OpaqueTypeCollector<'tcx> {
// start seeing the error below.
// Collect opaque types nested within the associated type bounds of this opaque type.
// We use identity substs here, because we already know that the opaque type uses
// only generic parameters, and thus substituting would not give us more information.
for (pred, span) in self
.tcx
.explicit_item_bounds(alias_ty.def_id)
.subst_iter_copied(self.tcx, alias_ty.substs)
.subst_identity_iter_copied()
{
trace!(?pred);
self.visit_spanned(span, pred);
@ -158,6 +160,25 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for OpaqueTypeCollector<'tcx> {
}
}
}
ty::Adt(def, _) if def.did().is_local() => {
if !self.seen.insert(def.did().expect_local()) {
return ControlFlow::Continue(());
}
for variant in def.variants().iter() {
for field in variant.fields.iter() {
// Don't use the `ty::Adt` substs, we either
// * found the opaque in the substs
// * will find the opaque in the unsubstituted fields
// The only other situation that can occur is that after substituting,
// some projection resolves to an opaque that we would have otherwise
// not found. While we could substitute and walk those, that would mean we
// would have to walk all substitutions of an Adt, which can quickly
// degenerate into looking at an exponential number of types.
let ty = self.tcx.type_of(field.did).subst_identity();
self.visit_spanned(self.tcx.def_span(field.did), ty);
}
}
}
_ => trace!(kind=?t.kind()),
}
ControlFlow::Continue(())