bjoernager/rust
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Handle type params in insig dtors

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This commit is contained in:
Aman Arora 2021-09-21 05:06:19 -04:00
parent 1c989880a1
commit d2cbe21756
3 changed files with 61 additions and 27 deletions
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26
compiler/rustc_ty_utils/src/needs_drop.rs
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@ -3,6 +3,7 @@
use rustc_data_structures::fx::FxHashSet;
use rustc_hir::def_id::DefId;
use rustc_middle::ty::subst::Subst;
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::util::{needs_drop_components, AlwaysRequiresDrop};
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_session::Limit;
@ -12,7 +13,7 @@ type NeedsDropResult<T> = Result<T, AlwaysRequiresDrop>;
fn needs_drop_raw<'tcx>(tcx: TyCtxt<'tcx>, query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool {
let adt_components =
move |adt_def: &ty::AdtDef| tcx.adt_drop_tys(adt_def.did).map(|tys| tys.iter());
move |adt_def: &ty::AdtDef, _| tcx.adt_drop_tys(adt_def.did).map(|tys| tys.iter());
// If we don't know a type doesn't need drop, for example if it's a type
// parameter without a `Copy` bound, then we conservatively return that it
@ -28,8 +29,9 @@ fn has_significant_drop_raw<'tcx>(
tcx: TyCtxt<'tcx>,
query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> bool {
let significant_drop_fields =
move |adt_def: &ty::AdtDef| tcx.adt_significant_drop_tys(adt_def.did).map(|tys| tys.iter());
let significant_drop_fields = move |adt_def: &ty::AdtDef, _| {
tcx.adt_significant_drop_tys(adt_def.did).map(|tys| tys.iter())
};
let res = NeedsDropTypes::new(tcx, query.param_env, query.value, significant_drop_fields)
.next()
.is_some();
@ -74,7 +76,7 @@ impl<'tcx, F> NeedsDropTypes<'tcx, F> {
impl<'tcx, F, I> Iterator for NeedsDropTypes<'tcx, F>
where
F: Fn(&ty::AdtDef) -> NeedsDropResult<I>,
F: Fn(&ty::AdtDef, SubstsRef<'tcx>) -> NeedsDropResult<I>,
I: Iterator<Item = Ty<'tcx>>,
{
type Item = NeedsDropResult<Ty<'tcx>>;
@ -138,7 +140,7 @@ 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) {
let tys = match (self.adt_components)(adt_def, substs) {
Err(e) => return Some(Err(e)),
Ok(tys) => tys,
};
@ -185,12 +187,12 @@ enum DtorType {
// Depending on the implentation of `adt_has_dtor`, it is used to check if the
// ADT has a destructor or if the ADT only has a significant destructor. For
// understanding significant destructor look at `adt_significant_drop_tys`.
fn adt_drop_tys_helper(
tcx: TyCtxt<'_>,
fn adt_drop_tys_helper<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: DefId,
adt_has_dtor: impl Fn(&ty::AdtDef) -> Option<DtorType>,
) -> Result<&ty::List<Ty<'_>>, AlwaysRequiresDrop> {
let adt_components = move |adt_def: &ty::AdtDef| {
) -> Result<&ty::List<Ty<'tcx>>, AlwaysRequiresDrop> {
let adt_components = move |adt_def: &ty::AdtDef, substs: SubstsRef<'tcx>| {
if adt_def.is_manually_drop() {
debug!("adt_drop_tys: `{:?}` is manually drop", adt_def);
return Ok(Vec::new().into_iter());
@ -202,7 +204,11 @@ fn adt_drop_tys_helper(
}
DtorType::Insignificant => {
debug!("adt_drop_tys: `{:?}` drop is insignificant", adt_def);
return Ok(Vec::new().into_iter());
// 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.
return Ok(substs.types().collect::<Vec<Ty<'_>>>().into_iter());
}
}
} else if adt_def.is_union() {