emit only one note per unused struct field
This commit is contained in:
Takayuki Maeda
parent
5fb8a39266
commit
da27551f3a
@ -164,10 +164,9 @@ fn check_for_self_assign_helper<'tcx>(
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if let (Res::Local(id_l), Res::Local(id_r)) = (
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typeck_results.qpath_res(qpath_l, lhs.hir_id),
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typeck_results.qpath_res(qpath_r, rhs.hir_id),
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) {
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if id_l == id_r {
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return true;
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}
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) && id_l == id_r
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{
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return true;
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}
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return false;
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}
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@ -183,10 +182,10 @@ fn check_for_self_assign_helper<'tcx>(
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}
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}
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if let hir::ExprKind::Assign(lhs, rhs, _) = assign.kind {
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if check_for_self_assign_helper(self.typeck_results(), lhs, rhs)
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if let hir::ExprKind::Assign(lhs, rhs, _) = assign.kind
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&& check_for_self_assign_helper(self.typeck_results(), lhs, rhs)
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&& !assign.span.from_expansion()
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{
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{
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let is_field_assign = matches!(lhs.kind, hir::ExprKind::Field(..));
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self.tcx.struct_span_lint_hir(
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lint::builtin::DEAD_CODE,
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@ -201,7 +200,6 @@ fn check_for_self_assign_helper<'tcx>(
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.emit();
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},
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)
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}
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}
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}
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@ -251,19 +249,19 @@ fn should_ignore_item(&mut self, def_id: DefId) -> bool {
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return false;
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}
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if let Some(trait_of) = self.tcx.trait_id_of_impl(impl_of) {
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if self.tcx.has_attr(trait_of, sym::rustc_trivial_field_reads) {
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let trait_ref = self.tcx.impl_trait_ref(impl_of).unwrap();
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if let ty::Adt(adt_def, _) = trait_ref.self_ty().kind() {
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if let Some(adt_def_id) = adt_def.did().as_local() {
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self.ignored_derived_traits
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.entry(adt_def_id)
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.or_default()
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.push((trait_of, impl_of));
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}
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}
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return true;
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if let Some(trait_of) = self.tcx.trait_id_of_impl(impl_of)
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&& self.tcx.has_attr(trait_of, sym::rustc_trivial_field_reads)
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{
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let trait_ref = self.tcx.impl_trait_ref(impl_of).unwrap();
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if let ty::Adt(adt_def, _) = trait_ref.self_ty().kind()
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&& let Some(adt_def_id) = adt_def.did().as_local()
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{
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self.ignored_derived_traits
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.entry(adt_def_id)
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.or_default()
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.push((trait_of, impl_of));
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}
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return true;
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}
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}
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@ -271,13 +269,13 @@ fn should_ignore_item(&mut self, def_id: DefId) -> bool {
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}
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fn visit_node(&mut self, node: Node<'tcx>) {
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if let Some(item_def_id) = match node {
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Node::ImplItem(hir::ImplItem { def_id, .. }) => Some(def_id.to_def_id()),
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_ => None,
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} {
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if self.should_ignore_item(item_def_id) {
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match node {
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Node::ImplItem(hir::ImplItem { def_id, .. })
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if self.should_ignore_item(def_id.to_def_id()) =>
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{
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return;
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}
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_ => (),
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}
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let had_repr_c = self.repr_has_repr_c;
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@ -534,10 +532,10 @@ fn check_item<'tcx>(
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}
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DefKind::Struct => {
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let item = tcx.hir().item(id);
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if let hir::ItemKind::Struct(ref variant_data, _) = item.kind {
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if let Some(ctor_hir_id) = variant_data.ctor_hir_id() {
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struct_constructors.insert(tcx.hir().local_def_id(ctor_hir_id), item.def_id);
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}
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if let hir::ItemKind::Struct(ref variant_data, _) = item.kind
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&& let Some(ctor_hir_id) = variant_data.ctor_hir_id()
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{
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struct_constructors.insert(tcx.hir().local_def_id(ctor_hir_id), item.def_id);
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}
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}
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DefKind::GlobalAsm => {
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@ -630,6 +628,7 @@ struct DeadVisitor<'tcx> {
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tcx: TyCtxt<'tcx>,
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live_symbols: &'tcx FxHashSet<LocalDefId>,
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ignored_derived_traits: &'tcx FxHashMap<LocalDefId, Vec<(DefId, DefId)>>,
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ignored_struct_def: FxHashSet<LocalDefId>,
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}
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impl<'tcx> DeadVisitor<'tcx> {
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@ -677,10 +676,10 @@ fn symbol_is_live(&mut self, def_id: LocalDefId) -> bool {
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let inherent_impls = self.tcx.inherent_impls(def_id);
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for &impl_did in inherent_impls.iter() {
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for item_did in self.tcx.associated_item_def_ids(impl_did) {
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if let Some(def_id) = item_did.as_local() {
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if self.live_symbols.contains(&def_id) {
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return true;
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}
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if let Some(def_id) = item_did.as_local()
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&& self.live_symbols.contains(&def_id)
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{
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return true;
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}
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}
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}
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@ -698,9 +697,20 @@ fn warn_dead_code(
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self.tcx.struct_span_lint_hir(lint::builtin::DEAD_CODE, id, span, |lint| {
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let def_id = self.tcx.hir().local_def_id(id);
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let descr = self.tcx.def_kind(def_id).descr(def_id.to_def_id());
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let mut err = lint.build(&format!("{} is never {}: `{}`", descr, participle, name));
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let mut err = lint.build(&format!("{descr} is never {participle}: `{name}`"));
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let hir = self.tcx.hir();
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if let Some(encl_scope) = hir.get_enclosing_scope(id)
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let is_field_in_same_struct =
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if let Some(parent_hir_id) = self.tcx.hir().find_parent_node(id)
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&& let Some(parent_node) = self.tcx.hir().find(parent_hir_id)
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&& let Node::Item(hir::Item{kind: hir::ItemKind::Struct(..), ..}) = parent_node
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&& let Some(did) = self.tcx.hir().opt_local_def_id(parent_hir_id)
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{
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!self.ignored_struct_def.insert(did)
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} else {
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false
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};
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if !is_field_in_same_struct
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&& let Some(encl_scope) = hir.get_enclosing_scope(id)
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&& let Some(encl_def_id) = hir.opt_local_def_id(encl_scope)
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&& let Some(ign_traits) = self.ignored_derived_traits.get(&encl_def_id)
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{
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@ -857,7 +867,12 @@ fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
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fn check_mod_deathness(tcx: TyCtxt<'_>, module: LocalDefId) {
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let (live_symbols, ignored_derived_traits) = tcx.live_symbols_and_ignored_derived_traits(());
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let mut visitor = DeadVisitor { tcx, live_symbols, ignored_derived_traits };
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let mut visitor = DeadVisitor {
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tcx,
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live_symbols,
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ignored_derived_traits,
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ignored_struct_def: FxHashSet::default(),
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};
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let (module, _, module_id) = tcx.hir().get_module(module);
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// Do not use an ItemLikeVisitor since we may want to skip visiting some items
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// when a surrounding one is warned against or `_`.
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@ -0,0 +1,12 @@
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#![forbid(dead_code)]
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#[derive(Debug)]
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pub struct Whatever {
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pub field0: (),
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field1: (), //~ERROR field is never read: `field1
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field2: (), //~ERROR field is never read: `field2
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field3: (), //~ERROR field is never read: `field3
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field4: (), //~ERROR field is never read: `field4
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}
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fn main() {}
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@ -0,0 +1,33 @@
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error: field is never read: `field1`
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--> $DIR/clone-debug-dead-code-in-the-same-struct.rs:6:5
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LL | field1: (),
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| ^^^^^^^^^^
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note: the lint level is defined here
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--> $DIR/clone-debug-dead-code-in-the-same-struct.rs:1:11
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LL | #![forbid(dead_code)]
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| ^^^^^^^^^
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= note: `Whatever` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
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error: field is never read: `field2`
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--> $DIR/clone-debug-dead-code-in-the-same-struct.rs:7:5
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LL | field2: (),
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| ^^^^^^^^^^
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error: field is never read: `field3`
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--> $DIR/clone-debug-dead-code-in-the-same-struct.rs:8:5
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LL | field3: (),
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| ^^^^^^^^^^
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error: field is never read: `field4`
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--> $DIR/clone-debug-dead-code-in-the-same-struct.rs:9:5
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LL | field4: (),
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| ^^^^^^^^^^
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error: aborting due to 4 previous errors
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