use rustc_data_structures::unord::{ExtendUnord, UnordSet};
use rustc_hir::def::DefKind;
use rustc_hir::def_id::LocalDefId;
use rustc_middle::query::Providers;
use rustc_middle::ty::TyCtxt;
use rustc_session::lint;
use tracing::debug;
pub(crate) fn provide(providers: &mut Providers) {
*providers = Providers { check_unused_traits, ..*providers };
}
fn check_unused_traits(tcx: TyCtxt<'_>, (): ()) {
let mut used_trait_imports = UnordSet::<LocalDefId>::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();
tcx.node_span_lint(lint::builtin::UNUSED_IMPORTS, item.hir_id(), path.span, |lint| {
if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(path.span) {
lint.primary_message(format!("unused import: `{snippet}`"));
} else {
lint.primary_message("unused import");
}
});
}
}