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unused_unit: small clean-up #15550

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Merged
merged 2 commits into from
Aug 24, 2025
Merged

unused_unit: small clean-up #15550

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852e552
get rid of confusing nested `map_or`s
ada4a Aug 23, 2025
e185efe
pattern-match on slices
ada4a Aug 23, 2025
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37 changes: 16 additions & 21 deletions clippy_lints/src/unused_unit.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ use rustc_hir::{
use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass};
use rustc_session::declare_lint_pass;
use rustc_span::edition::Edition;
use rustc_span::{BytePos, Span, sym};
use rustc_span::{BytePos, Pos as _, Span, sym};

declare_clippy_lint! {
/// ### What it does
Expand Down Expand Up @@ -97,16 +97,13 @@ impl<'tcx> LateLintPass<'tcx> for UnusedUnit {
}

fn check_poly_trait_ref(&mut self, cx: &LateContext<'tcx>, poly: &'tcx PolyTraitRef<'tcx>) {
let segments = &poly.trait_ref.path.segments;

if segments.len() == 1
&& matches!(segments[0].ident.name, sym::Fn | sym::FnMut | sym::FnOnce)
&& let Some(args) = segments[0].args
if let [segment] = &poly.trait_ref.path.segments
&& matches!(segment.ident.name, sym::Fn | sym::FnMut | sym::FnOnce)
&& let Some(args) = segment.args
&& args.parenthesized == GenericArgsParentheses::ParenSugar
&& let constraints = &args.constraints
&& constraints.len() == 1
&& constraints[0].ident.name == sym::Output
&& let AssocItemConstraintKind::Equality { term: Term::Ty(hir_ty) } = constraints[0].kind
&& let [constraint] = &args.constraints
&& constraint.ident.name == sym::Output
&& let AssocItemConstraintKind::Equality { term: Term::Ty(hir_ty) } = constraint.kind
&& args.span_ext.hi() != poly.span.hi()
&& !hir_ty.span.from_expansion()
&& args.span_ext.hi() != hir_ty.span.hi()
Expand Down Expand Up @@ -160,17 +157,15 @@ fn get_def(span: Span) -> Option<Span> {

fn lint_unneeded_unit_return(cx: &LateContext<'_>, ty_span: Span, span: Span) {
let (ret_span, appl) =
span.with_hi(ty_span.hi())
.get_source_text(cx)
.map_or((ty_span, Applicability::MaybeIncorrect), |src| {
position_before_rarrow(&src).map_or((ty_span, Applicability::MaybeIncorrect), |rpos| {
(
#[expect(clippy::cast_possible_truncation)]
ty_span.with_lo(BytePos(span.lo().0 + rpos as u32)),
Applicability::MachineApplicable,
)
})
});
if let Some(Some(rpos)) = span.with_hi(ty_span.hi()).with_source_text(cx, position_before_rarrow) {
(
ty_span.with_lo(span.lo() + BytePos::from_usize(rpos)),
Applicability::MachineApplicable,
)
} else {
(ty_span, Applicability::MaybeIncorrect)
};

span_lint_and_sugg(
cx,
UNUSED_UNIT,
Expand Down