bjoernager/rust
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dead_code treats #[repr(transparent)] the same as #[repr(C)]

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Fixes #119659
This commit is contained in:
Jake Goulding 2024-01-18 12:54:01 -05:00
parent a34faab155
commit d95d6ceecb
2 changed files with 24 additions and 8 deletions
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18
compiler/rustc_passes/src/dead.rs
View file

@ -57,7 +57,7 @@ struct MarkSymbolVisitor<'tcx> {
tcx: TyCtxt<'tcx>, tcx: TyCtxt<'tcx>,
maybe_typeck_results: Option<&'tcx ty::TypeckResults<'tcx>>, maybe_typeck_results: Option<&'tcx ty::TypeckResults<'tcx>>,
live_symbols: LocalDefIdSet, live_symbols: LocalDefIdSet,
repr_has_repr_c: bool, repr_unconditionally_treats_fields_as_live: bool,
repr_has_repr_simd: bool, repr_has_repr_simd: bool,
in_pat: bool, in_pat: bool,
ignore_variant_stack: Vec<DefId>, ignore_variant_stack: Vec<DefId>,
@ -365,15 +365,17 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
return; return;
} }
let had_repr_c = self.repr_has_repr_c; let unconditionally_treated_fields_as_live =
self.repr_unconditionally_treats_fields_as_live;
let had_repr_simd = self.repr_has_repr_simd; let had_repr_simd = self.repr_has_repr_simd;
self.repr_has_repr_c = false; self.repr_unconditionally_treats_fields_as_live = false;
self.repr_has_repr_simd = false; self.repr_has_repr_simd = false;
match node { match node {
Node::Item(item) => match item.kind { Node::Item(item) => match item.kind {
hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) => { hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) => {
let def = self.tcx.adt_def(item.owner_id); let def = self.tcx.adt_def(item.owner_id);
self.repr_has_repr_c = def.repr().c(); self.repr_unconditionally_treats_fields_as_live =
def.repr().c() || def.repr().transparent();
self.repr_has_repr_simd = def.repr().simd(); self.repr_has_repr_simd = def.repr().simd();
intravisit::walk_item(self, item) intravisit::walk_item(self, item)
@ -411,7 +413,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
_ => {} _ => {}
} }
self.repr_has_repr_simd = had_repr_simd; self.repr_has_repr_simd = had_repr_simd;
self.repr_has_repr_c = had_repr_c; self.repr_unconditionally_treats_fields_as_live = unconditionally_treated_fields_as_live;
} }
fn mark_as_used_if_union(&mut self, adt: ty::AdtDef<'tcx>, fields: &[hir::ExprField<'_>]) { fn mark_as_used_if_union(&mut self, adt: ty::AdtDef<'tcx>, fields: &[hir::ExprField<'_>]) {
@ -435,11 +437,11 @@ impl<'tcx> Visitor<'tcx> for MarkSymbolVisitor<'tcx> {
fn visit_variant_data(&mut self, def: &'tcx hir::VariantData<'tcx>) { fn visit_variant_data(&mut self, def: &'tcx hir::VariantData<'tcx>) {
let tcx = self.tcx; let tcx = self.tcx;
let has_repr_c = self.repr_has_repr_c; let unconditionally_treat_fields_as_live = self.repr_unconditionally_treats_fields_as_live;
let has_repr_simd = self.repr_has_repr_simd; let has_repr_simd = self.repr_has_repr_simd;
let live_fields = def.fields().iter().filter_map(|f| { let live_fields = def.fields().iter().filter_map(|f| {
let def_id = f.def_id; let def_id = f.def_id;
if has_repr_c || (f.is_positional() && has_repr_simd) { if unconditionally_treat_fields_as_live || (f.is_positional() && has_repr_simd) {
return Some(def_id); return Some(def_id);
} }
if !tcx.visibility(f.hir_id.owner.def_id).is_public() { if !tcx.visibility(f.hir_id.owner.def_id).is_public() {
@ -741,7 +743,7 @@ fn live_symbols_and_ignored_derived_traits(
tcx, tcx,
maybe_typeck_results: None, maybe_typeck_results: None,
live_symbols: Default::default(), live_symbols: Default::default(),
repr_has_repr_c: false, repr_unconditionally_treats_fields_as_live: false,
repr_has_repr_simd: false, repr_has_repr_simd: false,
in_pat: false, in_pat: false,
ignore_variant_stack: vec![], ignore_variant_stack: vec![],

14
tests/ui/lint/dead-code/type-in-transparent.rs Normal file
View file

@ -0,0 +1,14 @@
// Verify that we do not warn on fields that are part of transparent types.
// check-pass
#![deny(dead_code)]
#[repr(transparent)]
struct NamedStruct { field: u8 }
#[repr(transparent)]
struct TupleStruct(u8);
fn main() {
let _ = NamedStruct { field: 1 };
let _ = TupleStruct(1);
}