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len_zero: clean-up a bit #15518

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Merged
merged 3 commits into from
Aug 21, 2025
Merged

len_zero: clean-up a bit #15518

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5ec13c9
merge pats
ada4a Aug 19, 2025
6de463c
make a big let-chain
ada4a Aug 20, 2025
f177835
fix whatever this is
ada4a Aug 20, 2025
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41 changes: 15 additions & 26 deletions clippy_lints/src/len_zero.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -176,12 +176,11 @@ impl<'tcx> LateLintPass<'tcx> for LenZero {
if let ExprKind::Let(lt) = expr.kind
&& match lt.pat.kind {
PatKind::Slice([], None, []) => true,
PatKind::Expr(lit) => match lit.kind {
PatExprKind::Lit { lit, .. } => match lit.node {
LitKind::Str(lit, _) => lit.as_str().is_empty(),
_ => false,
},
_ => false,
PatKind::Expr(lit)
if let PatExprKind::Lit { lit, .. } = lit.kind
&& let LitKind::Str(lit, _) = lit.node =>
{
lit.as_str().is_empty()
},
_ => false,
}
Expand Down Expand Up @@ -336,33 +335,23 @@ fn extract_future_output<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<&
}

fn is_first_generic_integral<'tcx>(segment: &'tcx PathSegment<'tcx>) -> bool {
if let Some(generic_args) = segment.args {
if generic_args.args.is_empty() {
return false;
}
let arg = &generic_args.args[0];
if let GenericArg::Type(rustc_hir::Ty {
kind: TyKind::Path(QPath::Resolved(_, path)),
..
}) = arg
{
let segments = &path.segments;
let segment = &segments[0];
let res = &segment.res;
if matches!(res, Res::PrimTy(PrimTy::Uint(_))) || matches!(res, Res::PrimTy(PrimTy::Int(_))) {
return true;
}
}
if let Some(generic_args) = segment.args
&& let [GenericArg::Type(ty), ..] = &generic_args.args
&& let TyKind::Path(QPath::Resolved(_, path)) = ty.kind
&& let [segment, ..] = &path.segments
&& matches!(segment.res, Res::PrimTy(PrimTy::Uint(_) | PrimTy::Int(_)))
{
true
} else {
false
}

false
}

fn parse_len_output<'tcx>(cx: &LateContext<'tcx>, sig: FnSig<'tcx>) -> Option<LenOutput> {
if let Some(segment) = extract_future_output(cx, sig.output()) {
let res = segment.res;

if matches!(res, Res::PrimTy(PrimTy::Uint(_))) || matches!(res, Res::PrimTy(PrimTy::Int(_))) {
if matches!(res, Res::PrimTy(PrimTy::Uint(_) | PrimTy::Int(_))) {
return Some(LenOutput::Integral);
}

Expand Down