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Enhance collapsible_match to cover if-elses #16560

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Merged
llogiq merged 2 commits into from
Feb 22, 2026
Merged

Enhance collapsible_match to cover if-elses #16560

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904a750
Extend `collapsible_match` to cover `if-else`s
profetia Feb 13, 2026
5be3049
Apply `collapsible_match` to Clippy itself
profetia Feb 13, 2026
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18 changes: 7 additions & 11 deletions clippy_dev/src/new_lint.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -526,18 +526,14 @@ fn parse_mod_file(path: &Path, contents: &str) -> (&'static str, usize) {
let mut captures = [Capture::EMPTY];
while let Some(name) = cursor.find_any_ident() {
match cursor.get_text(name) {
"declare_clippy_lint" => {
if cursor.match_all(&[Bang, OpenBrace], &mut []) && cursor.find_pat(CloseBrace) {
decl_end = Some(cursor.pos());
}
"declare_clippy_lint" if cursor.match_all(&[Bang, OpenBrace], &mut []) && cursor.find_pat(CloseBrace) => {
decl_end = Some(cursor.pos());
},
"impl" => {
if cursor.match_all(&[Lt, Lifetime, Gt, CaptureIdent], &mut captures) {
match cursor.get_text(captures[0]) {
"LateLintPass" => context = Some("LateContext"),
"EarlyLintPass" => context = Some("EarlyContext"),
_ => {},
}
"impl" if cursor.match_all(&[Lt, Lifetime, Gt, CaptureIdent], &mut captures) => {
match cursor.get_text(captures[0]) {
"LateLintPass" => context = Some("LateContext"),
"EarlyLintPass" => context = Some("EarlyContext"),
_ => {},
}
},
_ => {},
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6 changes: 2 additions & 4 deletions clippy_lints/src/casts/unnecessary_cast.rs
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Expand Up @@ -39,10 +39,8 @@ pub(super) fn check<'tcx>(
// Ignore casts to pointers that are aliases or cfg dependant, e.g.
// - p as *const std::ffi::c_char (alias)
// - p as *const std::os::raw::c_char (cfg dependant)
TyKind::Path(qpath) => {
if is_ty_alias(&qpath) || is_hir_ty_cfg_dependant(cx, to_pointee.ty) {
return false;
}
TyKind::Path(qpath) if is_ty_alias(&qpath) || is_hir_ty_cfg_dependant(cx, to_pointee.ty) => {
return false;
},
// Ignore `p as *const _`
TyKind::Infer(()) => return false,
Expand Down
6 changes: 2 additions & 4 deletions clippy_lints/src/cognitive_complexity.rs
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Expand Up @@ -81,10 +81,8 @@ impl CognitiveComplexity {
}
cc += arms.iter().filter(|arm| arm.guard.is_some()).count() as u64;
},
ExprKind::Ret(_) => {
if !matches!(prev_expr, Some(ExprKind::Ret(_))) {
returns += 1;
}
ExprKind::Ret(_) if !matches!(prev_expr, Some(ExprKind::Ret(_))) => {
returns += 1;
},
_ => {},
}
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4 changes: 2 additions & 2 deletions clippy_lints/src/collapsible_if.rs
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Expand Up @@ -307,7 +307,7 @@ fn expr_block<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
}

/// If the expression is a `||`, suggest parentheses around it.
fn parens_around(expr: &Expr<'_>) -> Vec<(Span, String)> {
pub(super) fn parens_around(expr: &Expr<'_>) -> Vec<(Span, String)> {
if let ExprKind::Binary(op, _, _) = expr.peel_drop_temps().kind
&& op.node == BinOpKind::Or
{
Expand All @@ -334,7 +334,7 @@ fn span_extract_keyword(sm: &SourceMap, span: Span, keyword: &str) -> Option<Spa
}

/// Peel the parentheses from an `if` expression, e.g. `((if true {} else {}))`.
fn peel_parens(sm: &SourceMap, mut span: Span) -> (Span, Span, Span) {
pub(super) fn peel_parens(sm: &SourceMap, mut span: Span) -> (Span, Span, Span) {
use crate::rustc_span::Pos;

let start = span.shrink_to_lo();
Expand Down
16 changes: 4 additions & 12 deletions clippy_lints/src/doc/mod.rs
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Expand Up @@ -763,19 +763,11 @@ impl<'tcx> LateLintPass<'tcx> for Documentation {
self.check_private_items,
);
match item.kind {
ItemKind::Fn { sig, body, .. } => {
ItemKind::Fn { sig, body, .. }
if !(is_entrypoint_fn(cx, item.owner_id.to_def_id())
|| item.span.in_external_macro(cx.tcx.sess.source_map()))
{
missing_headers::check(
cx,
item.owner_id,
sig,
headers,
Some(body),
self.check_private_items,
);
}
|| item.span.in_external_macro(cx.tcx.sess.source_map())) =>
{
missing_headers::check(cx, item.owner_id, sig, headers, Some(body), self.check_private_items);
},
ItemKind::Trait(_, _, unsafety, ..) => match (headers.safety, unsafety) {
(false, Safety::Unsafe) => span_lint(
Expand Down
74 changes: 36 additions & 38 deletions clippy_lints/src/double_parens.rs
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Expand Up @@ -46,28 +46,28 @@ impl EarlyLintPass for DoubleParens {
// ((..))
// ^^^^^^ expr
// ^^^^ inner
ExprKind::Paren(inner) if matches!(inner.kind, ExprKind::Paren(_) | ExprKind::Tup(_)) => {
if expr.span.eq_ctxt(inner.span)
ExprKind::Paren(inner)
if matches!(inner.kind, ExprKind::Paren(_) | ExprKind::Tup(_))
&& expr.span.eq_ctxt(inner.span)
&& !expr.span.in_external_macro(cx.sess().source_map())
&& check_source(cx, inner)
{
// suggest removing the outer parens
&& check_source(cx, inner) =>
{
// suggest removing the outer parens

let mut applicability = Applicability::MachineApplicable;
// We don't need to use `snippet_with_context` here, because:
// - if `inner`'s `ctxt` is from macro, we don't lint in the first place (see the check above)
// - otherwise, calling `snippet_with_applicability` on a not-from-macro span is fine
let sugg = snippet_with_applicability(cx.sess(), inner.span, "_", &mut applicability);
span_lint_and_sugg(
cx,
DOUBLE_PARENS,
expr.span,
"unnecessary parentheses",
"remove them",
sugg.to_string(),
applicability,
);
}
let mut applicability = Applicability::MachineApplicable;
// We don't need to use `snippet_with_context` here, because:
// - if `inner`'s `ctxt` is from macro, we don't lint in the first place (see the check above)
// - otherwise, calling `snippet_with_applicability` on a not-from-macro span is fine
let sugg = snippet_with_applicability(cx.sess(), inner.span, "_", &mut applicability);
span_lint_and_sugg(
cx,
DOUBLE_PARENS,
expr.span,
"unnecessary parentheses",
"remove them",
sugg.to_string(),
applicability,
);
},

// func((n))
Expand All @@ -76,26 +76,24 @@ impl EarlyLintPass for DoubleParens {
// ^ inner
ExprKind::Call(_, args) | ExprKind::MethodCall(box MethodCall { args, .. })
if let [arg] = &**args
&& let ExprKind::Paren(inner) = &arg.kind =>
{
if expr.span.eq_ctxt(arg.span)
&& let ExprKind::Paren(inner) = &arg.kind
&& expr.span.eq_ctxt(arg.span)
&& !arg.span.in_external_macro(cx.sess().source_map())
&& check_source(cx, arg)
{
// suggest removing the inner parens
&& check_source(cx, arg) =>
{
// suggest removing the inner parens

let mut applicability = Applicability::MachineApplicable;
let sugg = snippet_with_context(cx.sess(), inner.span, arg.span.ctxt(), "_", &mut applicability).0;
span_lint_and_sugg(
cx,
DOUBLE_PARENS,
arg.span,
"unnecessary parentheses",
"remove them",
sugg.to_string(),
applicability,
);
}
let mut applicability = Applicability::MachineApplicable;
let sugg = snippet_with_context(cx.sess(), inner.span, arg.span.ctxt(), "_", &mut applicability).0;
span_lint_and_sugg(
cx,
DOUBLE_PARENS,
arg.span,
"unnecessary parentheses",
"remove them",
sugg.to_string(),
applicability,
);
},
_ => {},
}
Expand Down
6 changes: 2 additions & 4 deletions clippy_lints/src/infinite_iter.rs
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Expand Up @@ -252,10 +252,8 @@ fn complete_infinite_iter(cx: &LateContext<'_>, expr: &Expr<'_>) -> Finiteness {
}
}
},
ExprKind::Binary(op, l, r) => {
if op.node.is_comparison() {
return is_infinite(cx, l).and(is_infinite(cx, r)).and(MaybeInfinite);
}
ExprKind::Binary(op, l, r) if op.node.is_comparison() => {
return is_infinite(cx, l).and(is_infinite(cx, r)).and(MaybeInfinite);
}, // TODO: ExprKind::Loop + Match
_ => (),
}
Expand Down
24 changes: 11 additions & 13 deletions clippy_lints/src/loops/utils.rs
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Expand Up @@ -57,19 +57,17 @@ impl<'tcx> Visitor<'tcx> for IncrementVisitor<'_, 'tcx> {
}

match parent.kind {
ExprKind::AssignOp(op, lhs, rhs) => {
if lhs.hir_id == expr.hir_id {
*state = if op.node == AssignOpKind::AddAssign
&& is_integer_const(self.cx, rhs, 1)
&& *state == IncrementVisitorVarState::Initial
&& self.depth == 0
{
IncrementVisitorVarState::IncrOnce
} else {
// Assigned some other value or assigned multiple times
IncrementVisitorVarState::DontWarn
};
}
ExprKind::AssignOp(op, lhs, rhs) if lhs.hir_id == expr.hir_id => {
*state = if op.node == AssignOpKind::AddAssign
&& is_integer_const(self.cx, rhs, 1)
&& *state == IncrementVisitorVarState::Initial
&& self.depth == 0
{
IncrementVisitorVarState::IncrOnce
} else {
// Assigned some other value or assigned multiple times
IncrementVisitorVarState::DontWarn
};
},
ExprKind::Assign(lhs, _, _) if lhs.hir_id == expr.hir_id => {
*state = IncrementVisitorVarState::DontWarn;
Expand Down
39 changes: 14 additions & 25 deletions clippy_lints/src/manual_option_as_slice.rs
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Expand Up @@ -59,12 +59,11 @@ impl LateLintPass<'_> for ManualOptionAsSlice {
return;
}
match expr.kind {
ExprKind::Match(scrutinee, [arm1, arm2], _) => {
ExprKind::Match(scrutinee, [arm1, arm2], _)
if is_none_pattern(cx, arm2.pat) && check_arms(cx, arm2, arm1)
|| is_none_pattern(cx, arm1.pat) && check_arms(cx, arm1, arm2)
{
check_as_ref(cx, scrutinee, span, self.msrv);
}
|| is_none_pattern(cx, arm1.pat) && check_arms(cx, arm1, arm2) =>
{
check_as_ref(cx, scrutinee, span, self.msrv);
},
ExprKind::If(cond, then, Some(other)) => {
if let ExprKind::Let(let_expr) = cond.kind
Expand All @@ -75,34 +74,24 @@ impl LateLintPass<'_> for ManualOptionAsSlice {
check_as_ref(cx, let_expr.init, span, self.msrv);
}
},
ExprKind::MethodCall(seg, callee, [], _) => {
if seg.ident.name == sym::unwrap_or_default {
check_map(cx, callee, span, self.msrv);
}
ExprKind::MethodCall(seg, callee, [], _) if seg.ident.name == sym::unwrap_or_default => {
check_map(cx, callee, span, self.msrv);
},
ExprKind::MethodCall(seg, callee, [or], _) => match seg.ident.name {
sym::unwrap_or => {
if is_empty_slice(cx, or) {
check_map(cx, callee, span, self.msrv);
}
sym::unwrap_or if is_empty_slice(cx, or) => {
check_map(cx, callee, span, self.msrv);
},
sym::unwrap_or_else => {
if returns_empty_slice(cx, or) {
check_map(cx, callee, span, self.msrv);
}
sym::unwrap_or_else if returns_empty_slice(cx, or) => {
check_map(cx, callee, span, self.msrv);
},
_ => {},
},
ExprKind::MethodCall(seg, callee, [or_else, map], _) => match seg.ident.name {
sym::map_or => {
if is_empty_slice(cx, or_else) && is_slice_from_ref(cx, map) {
check_as_ref(cx, callee, span, self.msrv);
}
sym::map_or if is_empty_slice(cx, or_else) && is_slice_from_ref(cx, map) => {
check_as_ref(cx, callee, span, self.msrv);
},
sym::map_or_else => {
if returns_empty_slice(cx, or_else) && is_slice_from_ref(cx, map) {
check_as_ref(cx, callee, span, self.msrv);
}
sym::map_or_else if returns_empty_slice(cx, or_else) && is_slice_from_ref(cx, map) => {
check_as_ref(cx, callee, span, self.msrv);
},
_ => {},
},
Expand Down
21 changes: 10 additions & 11 deletions clippy_lints/src/manual_strip.rs
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Expand Up @@ -242,13 +242,13 @@ fn find_stripping<'tcx>(
&& self.cx.qpath_res(path, ex.hir_id) == self.target
{
match (self.strip_kind, start, end) {
(StripKind::Prefix, Some(start), None) => {
if eq_pattern_length(self.cx, self.pattern, start, self.ctxt) {
self.results.push(ex);
return;
}
(StripKind::Prefix, Some(start), None)
if eq_pattern_length(self.cx, self.pattern, start, self.ctxt) =>
{
self.results.push(ex);
return;
},
(StripKind::Suffix, None, Some(end)) => {
(StripKind::Suffix, None, Some(end))
if let ExprKind::Binary(
Spanned {
node: BinOpKind::Sub, ..
Expand All @@ -259,11 +259,10 @@ fn find_stripping<'tcx>(
&& let Some(left_arg) = len_arg(self.cx, left)
&& let ExprKind::Path(left_path) = &left_arg.kind
&& self.cx.qpath_res(left_path, left_arg.hir_id) == self.target
&& eq_pattern_length(self.cx, self.pattern, right, self.ctxt)
{
self.results.push(ex);
return;
}
&& eq_pattern_length(self.cx, self.pattern, right, self.ctxt) =>
{
self.results.push(ex);
return;
},
_ => {},
}
Expand Down
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