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use rustc_data_structures::unord::UnordSet;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::LocalDefId;
use rustc_middle::ty::TyCtxt;
use rustc_session::lint;
pub fn check_crate(tcx: TyCtxt<'_>) {
let mut used_trait_imports: UnordSet<LocalDefId> = Default::default();
for item_def_id in tcx.hir().body_owners() {
let imports = tcx.used_trait_imports(item_def_id);
debug!("GatherVisitor: item_def_id={:?} with imports {:#?}", item_def_id, imports);
used_trait_imports.extend_unord(imports.items().copied());
}
for &id in tcx.maybe_unused_trait_imports(()) {
debug_assert_eq!(tcx.def_kind(id), DefKind::Use);
if tcx.visibility(id).is_public() {
continue;
}
if used_trait_imports.contains(&id) {
continue;
}
let item = tcx.hir().expect_item(id);
if item.span.is_dummy() {
continue;
}
let (path, _) = item.expect_use();
let msg = if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(path.span) {
format!("unused import: `{}`", snippet)
} else {
"unused import".to_owned()
};
tcx.struct_span_lint_hir(
lint::builtin::UNUSED_IMPORTS,
item.hir_id(),
path.span,
msg,
|lint| lint,
);
}
}
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