Skip to content

is_ty_must_use: do not require a span argument #153063

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
rust-bors merged 1 commit into from
Feb 26, 2026
Merged

is_ty_must_use: do not require a span argument #153063

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
31 changes: 15 additions & 16 deletions compiler/rustc_lint/src/unused/must_use.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -151,7 +151,6 @@ pub fn is_ty_must_use<'tcx>(
cx: &LateContext<'tcx>,
ty: Ty<'tcx>,
expr: &hir::Expr<'_>,
span: Span,
simplify_uninhabited: bool,
) -> IsTyMustUse {
if ty.is_unit() {
Expand All @@ -165,12 +164,12 @@ pub fn is_ty_must_use<'tcx>(
match *ty.kind() {
_ if is_uninhabited(ty) => IsTyMustUse::Trivial,
ty::Adt(..) if let Some(boxed) = ty.boxed_ty() => {
is_ty_must_use(cx, boxed, expr, span, simplify_uninhabited)
is_ty_must_use(cx, boxed, expr, simplify_uninhabited)
.map(|inner| MustUsePath::Boxed(Box::new(inner)))
}
ty::Adt(def, args) if cx.tcx.is_lang_item(def.did(), LangItem::Pin) => {
let pinned_ty = args.type_at(0);
is_ty_must_use(cx, pinned_ty, expr, span, simplify_uninhabited)
is_ty_must_use(cx, pinned_ty, expr, simplify_uninhabited)
.map(|inner| MustUsePath::Pinned(Box::new(inner)))
}
// Consider `Result<T, Uninhabited>` (e.g. `Result<(), !>`) equivalent to `T`.
Expand All @@ -180,7 +179,7 @@ pub fn is_ty_must_use<'tcx>(
&& is_uninhabited(args.type_at(1)) =>
{
let ok_ty = args.type_at(0);
is_ty_must_use(cx, ok_ty, expr, span, simplify_uninhabited)
is_ty_must_use(cx, ok_ty, expr, simplify_uninhabited)
.map(|path| MustUsePath::Result(Box::new(path)))
}
// Consider `ControlFlow<Uninhabited, T>` (e.g. `ControlFlow<!, ()>`) equivalent to `T`.
Expand All @@ -190,7 +189,7 @@ pub fn is_ty_must_use<'tcx>(
&& is_uninhabited(args.type_at(0)) =>
{
let continue_ty = args.type_at(1);
is_ty_must_use(cx, continue_ty, expr, span, simplify_uninhabited)
is_ty_must_use(cx, continue_ty, expr, simplify_uninhabited)
.map(|path| MustUsePath::ControlFlow(Box::new(path)))
}
// Suppress warnings on `Result<(), Uninhabited>` (e.g. `Result<(), !>`).
Expand All @@ -210,7 +209,7 @@ pub fn is_ty_must_use<'tcx>(
IsTyMustUse::Trivial
}
ty::Adt(def, _) => {
is_def_must_use(cx, def.did(), span).map_or(IsTyMustUse::No, IsTyMustUse::Yes)
is_def_must_use(cx, def.did(), expr.span).map_or(IsTyMustUse::No, IsTyMustUse::Yes)
}
ty::Alias(ty::Opaque | ty::Projection, ty::AliasTy { def_id: def, .. }) => {
elaborate(cx.tcx, cx.tcx.explicit_item_self_bounds(def).iter_identity_copied())
Expand All @@ -223,7 +222,7 @@ pub fn is_ty_must_use<'tcx>(
{
let def_id = poly_trait_predicate.trait_ref.def_id;

is_def_must_use(cx, def_id, span)
is_def_must_use(cx, def_id, expr.span)
} else {
None
}
Expand All @@ -236,7 +235,7 @@ pub fn is_ty_must_use<'tcx>(
.find_map(|predicate| {
if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
let def_id = trait_ref.def_id;
is_def_must_use(cx, def_id, span)
is_def_must_use(cx, def_id, expr.span)
.map(|inner| MustUsePath::TraitObject(Box::new(inner)))
} else {
None
Expand All @@ -260,9 +259,7 @@ pub fn is_ty_must_use<'tcx>(
.zip(elem_exprs)
.enumerate()
.filter_map(|(i, (ty, expr))| {
is_ty_must_use(cx, ty, expr, expr.span, simplify_uninhabited)
.yes()
.map(|path| (i, path))
is_ty_must_use(cx, ty, expr, simplify_uninhabited).yes().map(|path| (i, path))
})
.collect::<Vec<_>>();

Expand All @@ -276,21 +273,23 @@ pub fn is_ty_must_use<'tcx>(
// If the array is empty we don't lint, to avoid false positives
Some(0) | None => IsTyMustUse::No,
// If the array is definitely non-empty, we can do `#[must_use]` checking.
Some(len) => is_ty_must_use(cx, ty, expr, span, simplify_uninhabited)
Some(len) => is_ty_must_use(cx, ty, expr, simplify_uninhabited)
.map(|inner| MustUsePath::Array(Box::new(inner), len)),
},
ty::Closure(..) | ty::CoroutineClosure(..) => IsTyMustUse::Yes(MustUsePath::Closure(span)),
ty::Closure(..) | ty::CoroutineClosure(..) => {
IsTyMustUse::Yes(MustUsePath::Closure(expr.span))
}
ty::Coroutine(def_id, ..) => {
// async fn should be treated as "implementor of `Future`"
if cx.tcx.coroutine_is_async(def_id)
&& let Some(def_id) = cx.tcx.lang_items().future_trait()
{
IsTyMustUse::Yes(MustUsePath::Opaque(Box::new(
is_def_must_use(cx, def_id, span)
is_def_must_use(cx, def_id, expr.span)
.expect("future trait is marked as `#[must_use]`"),
)))
} else {
IsTyMustUse::Yes(MustUsePath::Coroutine(span))
IsTyMustUse::Yes(MustUsePath::Coroutine(expr.span))
}
}
_ => IsTyMustUse::No,
Expand Down Expand Up @@ -339,7 +338,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {

let ty = cx.typeck_results().expr_ty(expr);

let must_use_result = is_ty_must_use(cx, ty, expr, expr.span, false);
let must_use_result = is_ty_must_use(cx, ty, expr, false);
let type_lint_emitted_or_trivial = match must_use_result {
IsTyMustUse::Yes(path) => {
emit_must_use_untranslated(cx, &path, "", "", 1, false, expr_is_from_block);
Expand Down
Loading