diff options
| -rw-r--r-- | compiler/rustc_passes/src/dead.rs | 91 | ||||
| -rw-r--r-- | tests/ui/lint/dead-code/issue-41883.rs | 29 | ||||
| -rw-r--r-- | tests/ui/lint/dead-code/issue-41883.stderr | 36 |
3 files changed, 136 insertions, 20 deletions
diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs index d19987cb33c..e11102c459e 100644 --- a/compiler/rustc_passes/src/dead.rs +++ b/compiler/rustc_passes/src/dead.rs @@ -4,6 +4,7 @@ // is dead. use hir::def_id::{LocalDefIdMap, LocalDefIdSet}; +use hir::ItemKind; use rustc_data_structures::unord::UnordSet; use rustc_errors::MultiSpan; use rustc_hir as hir; @@ -14,7 +15,7 @@ use rustc_hir::{Node, PatKind, TyKind}; use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags; use rustc_middle::middle::privacy::Level; use rustc_middle::query::Providers; -use rustc_middle::ty::{self, TyCtxt}; +use rustc_middle::ty::{self, TyCtxt, Visibility}; use rustc_session::lint; use rustc_session::lint::builtin::DEAD_CODE; use rustc_span::symbol::{sym, Symbol}; @@ -381,9 +382,46 @@ impl<'tcx> MarkSymbolVisitor<'tcx> { intravisit::walk_item(self, item) } hir::ItemKind::ForeignMod { .. } => {} + hir::ItemKind::Trait(..) => { + for impl_def_id in self.tcx.all_impls(item.owner_id.to_def_id()) { + if let Some(local_def_id) = impl_def_id.as_local() + && let ItemKind::Impl(impl_ref) = + self.tcx.hir().expect_item(local_def_id).kind + { + // skip items + // mark dependent traits live + intravisit::walk_generics(self, impl_ref.generics); + // mark dependent parameters live + intravisit::walk_path(self, impl_ref.of_trait.unwrap().path); + } + } + + intravisit::walk_item(self, item) + } _ => intravisit::walk_item(self, item), }, Node::TraitItem(trait_item) => { + // mark corresponing ImplTerm live + let trait_item_id = trait_item.owner_id.to_def_id(); + if let Some(trait_id) = self.tcx.trait_of_item(trait_item_id) { + // mark the trait live + self.check_def_id(trait_id); + + for impl_id in self.tcx.all_impls(trait_id) { + if let Some(local_impl_id) = impl_id.as_local() + && let ItemKind::Impl(impl_ref) = + self.tcx.hir().expect_item(local_impl_id).kind + { + // mark self_ty live + intravisit::walk_ty(self, impl_ref.self_ty); + if let Some(&impl_item_id) = + self.tcx.impl_item_implementor_ids(impl_id).get(&trait_item_id) + { + self.check_def_id(impl_item_id); + } + } + } + } intravisit::walk_trait_item(self, trait_item); } Node::ImplItem(impl_item) => { @@ -636,10 +674,6 @@ fn check_item<'tcx>( } } DefKind::Impl { of_trait } => { - if of_trait { - worklist.push((id.owner_id.def_id, ComesFromAllowExpect::No)); - } - // get DefIds from another query let local_def_ids = tcx .associated_item_def_ids(id.owner_id) @@ -648,7 +682,11 @@ fn check_item<'tcx>( // And we access the Map here to get HirId from LocalDefId for id in local_def_ids { - if of_trait { + // for impl trait blocks, mark associate functions live if the trait is public + if of_trait + && (!matches!(tcx.def_kind(id), DefKind::AssocFn) + || tcx.local_visibility(id) == Visibility::Public) + { worklist.push((id, ComesFromAllowExpect::No)); } else if let Some(comes_from_allow) = has_allow_dead_code_or_lang_attr(tcx, id) { worklist.push((id, comes_from_allow)); @@ -679,7 +717,7 @@ fn check_trait_item( use hir::TraitItemKind::{Const, Fn}; if matches!(tcx.def_kind(id.owner_id), DefKind::AssocConst | DefKind::AssocFn) { let trait_item = tcx.hir().trait_item(id); - if matches!(trait_item.kind, Const(_, Some(_)) | Fn(_, hir::TraitFn::Provided(_))) + if matches!(trait_item.kind, Const(_, Some(_)) | Fn(..)) && let Some(comes_from_allow) = has_allow_dead_code_or_lang_attr(tcx, trait_item.owner_id.def_id) { @@ -948,7 +986,8 @@ impl<'tcx> DeadVisitor<'tcx> { | DefKind::TyAlias | DefKind::Enum | DefKind::Union - | DefKind::ForeignTy => self.warn_dead_code(def_id, "used"), + | DefKind::ForeignTy + | DefKind::Trait => self.warn_dead_code(def_id, "used"), DefKind::Struct => self.warn_dead_code(def_id, "constructed"), DefKind::Variant | DefKind::Field => bug!("should be handled specially"), _ => {} @@ -973,18 +1012,33 @@ fn check_mod_deathness(tcx: TyCtxt<'_>, module: LocalModDefId) { let module_items = tcx.hir_module_items(module); for item in module_items.items() { - if let hir::ItemKind::Impl(impl_item) = tcx.hir().item(item).kind { - let mut dead_items = Vec::new(); - for item in impl_item.items { - let def_id = item.id.owner_id.def_id; - if !visitor.is_live_code(def_id) { - let name = tcx.item_name(def_id.to_def_id()); - let level = visitor.def_lint_level(def_id); + let def_kind = tcx.def_kind(item.owner_id); - dead_items.push(DeadItem { def_id, name, level }) + let mut dead_codes = Vec::new(); + // if we have diagnosed the trait, do not diagnose unused methods + if matches!(def_kind, DefKind::Impl { .. }) + || (def_kind == DefKind::Trait && live_symbols.contains(&item.owner_id.def_id)) + { + for &def_id in tcx.associated_item_def_ids(item.owner_id.def_id) { + // We have diagnosed unused methods in traits + if matches!(def_kind, DefKind::Impl { of_trait: true }) + && tcx.def_kind(def_id) == DefKind::AssocFn + || def_kind == DefKind::Trait && tcx.def_kind(def_id) != DefKind::AssocFn + { + continue; + } + + if let Some(local_def_id) = def_id.as_local() + && !visitor.is_live_code(local_def_id) + { + let name = tcx.item_name(def_id); + let level = visitor.def_lint_level(local_def_id); + dead_codes.push(DeadItem { def_id: local_def_id, name, level }); } } - visitor.warn_multiple(item.owner_id.def_id, "used", dead_items, ReportOn::NamedField); + } + if !dead_codes.is_empty() { + visitor.warn_multiple(item.owner_id.def_id, "used", dead_codes, ReportOn::NamedField); } if !live_symbols.contains(&item.owner_id.def_id) { @@ -997,7 +1051,6 @@ fn check_mod_deathness(tcx: TyCtxt<'_>, module: LocalModDefId) { continue; } - let def_kind = tcx.def_kind(item.owner_id); if let DefKind::Struct | DefKind::Union | DefKind::Enum = def_kind { let adt = tcx.adt_def(item.owner_id); let mut dead_variants = Vec::new(); @@ -1044,8 +1097,6 @@ fn check_mod_deathness(tcx: TyCtxt<'_>, module: LocalModDefId) { for foreign_item in module_items.foreign_items() { visitor.check_definition(foreign_item.owner_id.def_id); } - - // We do not warn trait items. } pub(crate) fn provide(providers: &mut Providers) { diff --git a/tests/ui/lint/dead-code/issue-41883.rs b/tests/ui/lint/dead-code/issue-41883.rs new file mode 100644 index 00000000000..e165861e893 --- /dev/null +++ b/tests/ui/lint/dead-code/issue-41883.rs @@ -0,0 +1,29 @@ +#![deny(dead_code)] + +enum Category { + Dead, //~ ERROR variant `Dead` is never constructed + Used, +} + +trait UnusedTrait { //~ ERROR trait `UnusedTrait` is never used + fn this_is_unused(&self) -> Category { + Category::Dead + } +} + +struct UnusedStruct; //~ ERROR struct `UnusedStruct` is never constructed + +impl UnusedTrait for UnusedStruct { + fn this_is_unused(&self) -> Category { + Category::Used + } +} + +mod private { + #[derive(Debug)] + struct UnusedStruct; //~ ERROR struct `UnusedStruct` is never constructed +} + +fn main() { + let _c = Category::Used; +} diff --git a/tests/ui/lint/dead-code/issue-41883.stderr b/tests/ui/lint/dead-code/issue-41883.stderr new file mode 100644 index 00000000000..cf079e4dda3 --- /dev/null +++ b/tests/ui/lint/dead-code/issue-41883.stderr @@ -0,0 +1,36 @@ +error: variant `Dead` is never constructed + --> $DIR/issue-41883.rs:4:5 + | +LL | enum Category { + | -------- variant in this enum +LL | Dead, + | ^^^^ + | +note: the lint level is defined here + --> $DIR/issue-41883.rs:1:9 + | +LL | #![deny(dead_code)] + | ^^^^^^^^^ + +error: trait `UnusedTrait` is never used + --> $DIR/issue-41883.rs:8:7 + | +LL | trait UnusedTrait { + | ^^^^^^^^^^^ + +error: struct `UnusedStruct` is never constructed + --> $DIR/issue-41883.rs:14:8 + | +LL | struct UnusedStruct; + | ^^^^^^^^^^^^ + +error: struct `UnusedStruct` is never constructed + --> $DIR/issue-41883.rs:24:12 + | +LL | struct UnusedStruct; + | ^^^^^^^^^^^^ + | + = note: `UnusedStruct` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis + +error: aborting due to 4 previous errors + |