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Make TAITs capture all higher-ranked lifetimes in scope

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This commit is contained in:
Michael Goulet 2024-03-06 17:52:53 +00:00
parent 9823f17315
commit cf299ddb6e
17 changed files with 122 additions and 152 deletions
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56
compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs
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@ -514,38 +514,11 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
// These sorts of items have no lifetime parameters at all.
intravisit::walk_item(self, item);
}
hir::ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::TyAlias { .. },
..
}) => {
// Opaque types are visited when we visit the
// `TyKind::OpaqueDef`, so that they have the lifetimes from
// their parent opaque_ty in scope.
//
// The core idea here is that since OpaqueTys are generated with the impl Trait as
// their owner, we can keep going until we find the Item that owns that. We then
// conservatively add all resolved lifetimes. Otherwise we run into problems in
// cases like `type Foo<'a> = impl Bar<As = impl Baz + 'a>`.
let parent_item = self.tcx.hir().get_parent_item(item.hir_id());
let resolved_lifetimes: &ResolveBoundVars =
self.tcx.resolve_bound_vars(parent_item);
// We need to add *all* deps, since opaque tys may want them from *us*
for (&owner, defs) in resolved_lifetimes.defs.iter() {
defs.iter().for_each(|(&local_id, region)| {
self.map.defs.insert(hir::HirId { owner, local_id }, *region);
});
}
for (&owner, late_bound_vars) in resolved_lifetimes.late_bound_vars.iter() {
late_bound_vars.iter().for_each(|(&local_id, late_bound_vars)| {
self.record_late_bound_vars(
hir::HirId { owner, local_id },
late_bound_vars.clone(),
);
});
}
}
hir::ItemKind::OpaqueTy(&hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent),
origin:
hir::OpaqueTyOrigin::FnReturn(parent)
| hir::OpaqueTyOrigin::AsyncFn(parent)
| hir::OpaqueTyOrigin::TyAlias { parent, .. },
generics,
..
}) => {
@ -683,26 +656,7 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
// the opaque_ty generics
let opaque_ty = self.tcx.hir().item(item_id);
match &opaque_ty.kind {
hir::ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::TyAlias { .. },
..
}) => {
intravisit::walk_ty(self, ty);
// Elided lifetimes and late-bound lifetimes (from the parent)
// are not allowed in non-return position impl Trait
let scope = Scope::LateBoundary {
s: &Scope::TraitRefBoundary { s: self.scope },
what: "type alias impl trait",
};
self.with(scope, |this| intravisit::walk_item(this, opaque_ty));
return;
}
hir::ItemKind::OpaqueTy(hir::OpaqueTy {
origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
..
}) => {}
hir::ItemKind::OpaqueTy(hir::OpaqueTy { origin: _, .. }) => {}
i => bug!("`impl Trait` pointed to non-opaque type?? {:#?}", i),
};