bjoernager/rust
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Auto merge of #95474 - oli-obk:tait_ub, r=jackh726

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Neither require nor imply lifetime bounds on opaque type for well formedness

The actual hidden type can live arbitrarily longer than any individual lifetime and arbitrarily shorter than all but one of the lifetimes.

fixes #86218
fixes #84305

This is a **breaking change** but it is a necessary soundness fix
This commit is contained in:
bors 2022-09-25 19:15:26 +00:00
commit f5193a9fcc
34 changed files with 696 additions and 153 deletions
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12
compiler/rustc_typeck/src/mem_categorization.rs
View file

@ -265,6 +265,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
self.cat_expr_adjusted_with(expr, || Ok(previous), adjustment)
}
#[instrument(level = "debug", skip(self, previous))]
fn cat_expr_adjusted_with<F>(
&self,
expr: &hir::Expr<'_>,
@ -274,7 +275,6 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
where
F: FnOnce() -> McResult<PlaceWithHirId<'tcx>>,
{
debug!("cat_expr_adjusted_with({:?}): {:?}", adjustment, expr);
let target = self.resolve_vars_if_possible(adjustment.target);
match adjustment.kind {
adjustment::Adjust::Deref(overloaded) => {
@ -299,6 +299,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
}
}
#[instrument(level = "debug", skip(self))]
pub(crate) fn cat_expr_unadjusted(
&self,
expr: &hir::Expr<'_>,
@ -387,6 +388,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
}
}
#[instrument(level = "debug", skip(self, span))]
pub(crate) fn cat_res(
&self,
hir_id: hir::HirId,
@ -394,8 +396,6 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
expr_ty: Ty<'tcx>,
res: Res,
) -> McResult<PlaceWithHirId<'tcx>> {
debug!("cat_res: id={:?} expr={:?} def={:?}", hir_id, expr_ty, res);
match res {
Res::Def(
DefKind::Ctor(..)
@ -475,13 +475,12 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
ret
}
#[instrument(level = "debug", skip(self))]
fn cat_overloaded_place(
&self,
expr: &hir::Expr<'_>,
base: &hir::Expr<'_>,
) -> McResult<PlaceWithHirId<'tcx>> {
debug!("cat_overloaded_place(expr={:?}, base={:?})", expr, base);
// Reconstruct the output assuming it's a reference with the
// same region and mutability as the receiver. This holds for
// `Deref(Mut)::Deref(_mut)` and `Index(Mut)::index(_mut)`.
@ -497,13 +496,12 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
self.cat_deref(expr, base)
}
#[instrument(level = "debug", skip(self, node))]
fn cat_deref(
&self,
node: &impl HirNode,
base_place: PlaceWithHirId<'tcx>,
) -> McResult<PlaceWithHirId<'tcx>> {
debug!("cat_deref: base_place={:?}", base_place);
let base_curr_ty = base_place.place.ty();
let deref_ty = match base_curr_ty.builtin_deref(true) {
Some(mt) => mt.ty,

17
compiler/rustc_typeck/src/outlives/utils.rs
View file

@ -96,6 +96,23 @@ pub(crate) fn insert_outlives_predicate<'tcx>(
.or_insert(span);
}
Component::Opaque(def_id, substs) => {
// This would arise from something like:
//
// ```rust
// type Opaque<T> = impl Sized;
// fn defining<T>() -> Opaque<T> {}
// struct Ss<'a, T>(&'a Opaque<T>);
// ```
//
// Here we want to have an implied bound `Opaque<T>: 'a`
let ty = tcx.mk_opaque(def_id, substs);
required_predicates
.entry(ty::OutlivesPredicate(ty.into(), outlived_region))
.or_insert(span);
}
Component::EscapingProjection(_) => {
// As above, but the projection involves
// late-bound regions. Therefore, the WF