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Handle trait objects

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This commit is contained in:
varkor 2018-11-03 20:24:24 +00:00
parent 122886842e
commit 9178eb41d3
1 changed files with 24 additions and 6 deletions
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30
src/librustc_lint/unused.rs
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@ -65,13 +65,25 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
true
} else {
match t.sty {
ty::Adt(def, _) => check_must_use(cx, def.did, s.span, ""),
ty::Adt(def, _) => check_must_use(cx, def.did, s.span, "", ""),
ty::Opaque(def, _) => {
let mut must_use = false;
for (predicate, _) in cx.tcx.predicates_of(def).predicates {
if let ty::Predicate::Trait(ref poly_trait_predicate) = predicate {
let trait_ref = poly_trait_predicate.skip_binder().trait_ref;
if check_must_use(cx, trait_ref.def_id, s.span, "implementer of ") {
if check_must_use(cx, trait_ref.def_id, s.span, "implementer of ", "") {
must_use = true;
break;
}
}
}
must_use
}
ty::Dynamic(binder, _) => {
let mut must_use = false;
for predicate in binder.skip_binder().iter() {
if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate {
if check_must_use(cx, trait_ref.def_id, s.span, "", " trait object") {
must_use = true;
break;
}
@ -107,7 +119,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
};
if let Some(def) = maybe_def {
let def_id = def.def_id();
fn_warned = check_must_use(cx, def_id, s.span, "return value of ");
fn_warned = check_must_use(cx, def_id, s.span, "return value of ", "");
} else if type_permits_lack_of_use {
// We don't warn about unused unit or uninhabited types.
// (See https://github.com/rust-lang/rust/issues/43806 for details.)
@ -161,11 +173,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
cx.span_lint(UNUSED_RESULTS, s.span, "unused result");
}
fn check_must_use(cx: &LateContext, def_id: DefId, sp: Span, describe_path: &str) -> bool {
fn check_must_use(
cx: &LateContext,
def_id: DefId,
sp: Span,
descr_pre_path: &str,
descr_post_path: &str,
) -> bool {
for attr in cx.tcx.get_attrs(def_id).iter() {
if attr.check_name("must_use") {
let msg = format!("unused {}`{}` that must be used",
describe_path, cx.tcx.item_path_str(def_id));
let msg = format!("unused {}`{}`{} that must be used",
descr_pre_path, descr_post_path, cx.tcx.item_path_str(def_id));
let mut err = cx.struct_span_lint(UNUSED_MUST_USE, sp, &msg);
// check for #[must_use = "..."]
if let Some(note) = attr.value_str() {