bjoernager/rust
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Detect unused structs which implement private traits

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This commit is contained in:
r0cky 2024-05-23 09:06:43 +08:00
parent 9cdfe285ca
commit 96968350e1
6 changed files with 84 additions and 17 deletions
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49
compiler/rustc_passes/src/dead.rs
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@ -425,10 +425,11 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
&& let ItemKind::Impl(impl_ref) =
self.tcx.hir().expect_item(local_impl_id).kind
{
if self.tcx.visibility(trait_id).is_public()
&& matches!(trait_item.kind, hir::TraitItemKind::Fn(..))
if matches!(trait_item.kind, hir::TraitItemKind::Fn(..))
&& !ty_ref_to_pub_struct(self.tcx, impl_ref.self_ty)
{
// skip methods of private ty,
// they would be solved in `solve_rest_impl_items`
continue;
}
@ -485,32 +486,46 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
fn solve_rest_impl_items(&mut self, mut unsolved_impl_items: Vec<(hir::ItemId, LocalDefId)>) {
let mut ready;
(ready, unsolved_impl_items) = unsolved_impl_items
.into_iter()
.partition(|&(impl_id, _)| self.impl_item_with_used_self(impl_id));
(ready, unsolved_impl_items) =
unsolved_impl_items.into_iter().partition(|&(impl_id, impl_item_id)| {
self.impl_item_with_used_self(impl_id, impl_item_id)
});
while !ready.is_empty() {
self.worklist =
ready.into_iter().map(|(_, id)| (id, ComesFromAllowExpect::No)).collect();
self.mark_live_symbols();
(ready, unsolved_impl_items) = unsolved_impl_items
.into_iter()
.partition(|&(impl_id, _)| self.impl_item_with_used_self(impl_id));
(ready, unsolved_impl_items) =
unsolved_impl_items.into_iter().partition(|&(impl_id, impl_item_id)| {
self.impl_item_with_used_self(impl_id, impl_item_id)
});
}
}
fn impl_item_with_used_self(&mut self, impl_id: hir::ItemId) -> bool {
fn impl_item_with_used_self(&mut self, impl_id: hir::ItemId, impl_item_id: LocalDefId) -> bool {
if let TyKind::Path(hir::QPath::Resolved(_, path)) =
self.tcx.hir().item(impl_id).expect_impl().self_ty.kind
&& let Res::Def(def_kind, def_id) = path.res
&& let Some(local_def_id) = def_id.as_local()
&& matches!(def_kind, DefKind::Struct | DefKind::Enum | DefKind::Union)
{
self.live_symbols.contains(&local_def_id)
} else {
false
if self.tcx.visibility(impl_item_id).is_public() {
// for the public method, we don't know the trait item is used or not,
// so we mark the method live if the self is used
return self.live_symbols.contains(&local_def_id);
}
if let Some(trait_item_id) = self.tcx.associated_item(impl_item_id).trait_item_def_id
&& let Some(local_id) = trait_item_id.as_local()
{
// for the private method, we can know the trait item is used or not,
// so we mark the method live if the self is used and the trait item is used
return self.live_symbols.contains(&local_id)
&& self.live_symbols.contains(&local_def_id);
}
}
false
}
}
@ -745,20 +760,22 @@ fn check_item<'tcx>(
matches!(fn_sig.decl.implicit_self, hir::ImplicitSelfKind::None);
}
// for impl trait blocks, mark associate functions live if the trait is public
// for trait impl blocks,
// mark the method live if the self_ty is public,
// or the method is public and may construct self
if of_trait
&& (!matches!(tcx.def_kind(local_def_id), DefKind::AssocFn)
|| tcx.visibility(local_def_id).is_public()
&& (ty_is_pub || may_construct_self))
{
worklist.push((local_def_id, ComesFromAllowExpect::No));
} else if of_trait && tcx.visibility(local_def_id).is_public() {
// pub method && private ty & methods not construct self
unsolved_impl_items.push((id, local_def_id));
} else if let Some(comes_from_allow) =
has_allow_dead_code_or_lang_attr(tcx, local_def_id)
{
worklist.push((local_def_id, comes_from_allow));
} else if of_trait {
// private method || public method not constructs self
unsolved_impl_items.push((id, local_def_id));
}
}
}