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Fix query cycle in needs drop code. #92804

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Fix query cycle in needs drop code. #92804

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101 changes: 53 additions & 48 deletions compiler/rustc_ty_utils/src/needs_drop.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,7 @@ impl<'tcx, F> NeedsDropTypes<'tcx, F> {

impl<'tcx, F, I> Iterator for NeedsDropTypes<'tcx, F>
where
F: Fn(&ty::AdtDef, SubstsRef<'tcx>) -> NeedsDropResult<I>,
F: Fn(&ty::AdtDef, SubstsRef<'tcx>, &FxHashSet<Ty<'tcx>>) -> NeedsDropResult<I>,
I: Iterator<Item = Ty<'tcx>>,
{
type Item = NeedsDropResult<Ty<'tcx>>;
Expand Down Expand Up @@ -142,7 +142,7 @@ where
// `ManuallyDrop`. If it's a struct or enum without a `Drop`
// impl then check whether the field types need `Drop`.
ty::Adt(adt_def, substs) => {
let tys = match (self.adt_components)(adt_def, substs) {
let tys = match (self.adt_components)(adt_def, substs, &self.seen_tys) {
Err(e) => return Some(Err(e)),
Ok(tys) => tys,
};
Expand Down Expand Up @@ -200,62 +200,67 @@ fn drop_tys_helper<'tcx>(
tcx: TyCtxt<'tcx>,
iter: impl IntoIterator<Item = Ty<'tcx>>,
only_significant: bool,
seen_tys: &FxHashSet<Ty<'tcx>>,
) -> NeedsDropResult<Vec<Ty<'tcx>>> {
iter.into_iter().try_fold(Vec::new(), |mut vec, subty| {
match subty.kind() {
ty::Adt(adt_id, subst) => {
for subty in if only_significant {
tcx.adt_significant_drop_tys(adt_id.did)?
} else {
tcx.adt_drop_tys(adt_id.did)?
} {
vec.push(subty.subst(tcx, subst));
if !seen_tys.contains(subty) {
match subty.kind() {
ty::Adt(adt_id, subst) => {
for subty in if only_significant {
tcx.adt_significant_drop_tys(adt_id.did)?
} else {
tcx.adt_drop_tys(adt_id.did)?
} {
vec.push(subty.subst(tcx, subst));
}
}
}
_ => vec.push(subty),
};
_ => vec.push(subty),
};
}
Ok(vec)
})
}

let adt_components = move |adt_def: &ty::AdtDef, substs: SubstsRef<'tcx>| {
if adt_def.is_manually_drop() {
debug!("drop_tys_helper: `{:?}` is manually drop", adt_def);
Ok(Vec::new())
} else if let Some(dtor_info) = adt_has_dtor(adt_def) {
match dtor_info {
DtorType::Significant => {
debug!("drop_tys_helper: `{:?}` implements `Drop`", adt_def);
Err(AlwaysRequiresDrop)
}
DtorType::Insignificant => {
debug!("drop_tys_helper: `{:?}` drop is insignificant", adt_def);
let adt_components =
move |adt_def: &ty::AdtDef, substs: SubstsRef<'tcx>, seen_tys: &FxHashSet<Ty<'tcx>>| {
if adt_def.is_manually_drop() {
debug!("drop_tys_helper: `{:?}` is manually drop", adt_def);
Ok(Vec::new())
} else if let Some(dtor_info) = adt_has_dtor(adt_def) {
match dtor_info {
DtorType::Significant => {
debug!("drop_tys_helper: `{:?}` implements `Drop`", adt_def);
Err(AlwaysRequiresDrop)
}
DtorType::Insignificant => {
debug!("drop_tys_helper: `{:?}` drop is insignificant", adt_def);

// Since the destructor is insignificant, we just want to make sure all of
// the passed in type parameters are also insignificant.
// Eg: Vec<T> dtor is insignificant when T=i32 but significant when T=Mutex.
with_query_cache(tcx, substs.types(), only_significant)
// Since the destructor is insignificant, we just want to make sure all of
// the passed in type parameters are also insignificant.
// Eg: Vec<T> dtor is insignificant when T=i32 but significant when T=Mutex.
with_query_cache(tcx, substs.types(), only_significant, seen_tys)
}
}
} else if adt_def.is_union() {
debug!("drop_tys_helper: `{:?}` is a union", adt_def);
Ok(Vec::new())
} else {
with_query_cache(
tcx,
adt_def.all_fields().map(|field| {
let r = tcx.type_of(field.did).subst(tcx, substs);
debug!(
"drop_tys_helper: Subst into {:?} with {:?} gettng {:?}",
field, substs, r
);
r
}),
only_significant,
seen_tys,
)
}
} else if adt_def.is_union() {
debug!("drop_tys_helper: `{:?}` is a union", adt_def);
Ok(Vec::new())
} else {
with_query_cache(
tcx,
adt_def.all_fields().map(|field| {
let r = tcx.type_of(field.did).subst(tcx, substs);
debug!(
"drop_tys_helper: Subst into {:?} with {:?} gettng {:?}",
field, substs, r
);
r
}),
only_significant,
)
}
.map(|v| v.into_iter())
};
.map(|v| v.into_iter())
};

NeedsDropTypes::new(tcx, param_env, ty, adt_components)
}
Expand Down
13 changes: 13 additions & 0 deletions src/test/ui/closures/2229_closure_analysis/issue-92724-needsdrop-query-cycle.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
// ICEs if checking if there is a significant destructor causes a query cycle
// check-pass

#![warn(rust_2021_incompatible_closure_captures)]
pub struct Foo(Bar);
pub struct Bar(Vec<Foo>);

impl Foo {
pub fn bar(self, v: Bar) -> Bar {
(|| v)()
}
}
fn main() {}