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final refactor and docs

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Ada Alakbarova 2025-10-09 21:33:24 +02:00
parent dd7f6058bf
commit 0535908499
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1 changed files with 59 additions and 5 deletions
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64
clippy_lints/src/matches/match_like_matches.rs
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@ -72,11 +72,65 @@ pub(super) fn check_match<'tcx>(
&& let Some(b0) = find_bool_lit(first_arm.body)
&& let Some(b1) = find_bool_lit(last_arm.body)
&& b0 != b1
&& (first_arm.guard.is_none() || middle_arms.is_empty())
&& cx.tcx.hir_attrs(first_arm.hir_id).is_empty()
&& middle_arms.iter().all(|arm| {
cx.tcx.hir_attrs(arm.hir_id).is_empty() && arm.guard.is_none() && find_bool_lit(arm.body) == Some(b0)
})
// We handle two cases:
&& (
// - There are no middle arms, i.e., 2 arms in total
//
// In that case, the first arm may or may not have a guard, because this:
// ```rs
// match e {
// Either::Left $(if $guard)|+ => true, // or `false`, but then we'll need `!matches!(..)`
// _ => false,
// }
// ```
// can always become this:
// ```rs
// matches!(e, Either::Left $(if $guard)|+)
// ```
middle_arms.is_empty()
// - (added in #6216) There are middle arms
//
// In that case, neither they nor the first arm may have guards
// -- otherwise, they couldn't be combined into an or-pattern in `matches!`
//
// This:
// ```rs
// match e {
// Either3::First => true,
// Either3::Second => true,
// _ /* matches `Either3::Third` */ => false,
// }
// ```
// can become this:
// ```rs
// matches!(e, Either3::First | Either3::Second)
// ```
//
// But this:
// ```rs
// match e {
// Either3::First if X => true,
// Either3::Second => true,
// _ => false,
// }
// ```
// cannot be transformed.
//
// We set an additional constraint of all of them needing to return the same bool,
// so we don't lint things like:
// ```rs
// match e {
// Either3::First => true,
// Either3::Second => false,
// _ => false,
// }
// ```
// This is not *strictly* necessary, but it simplifies the logic a bit
|| arms_without_last.iter().all(|arm| {
cx.tcx.hir_attrs(arm.hir_id).is_empty() && arm.guard.is_none() && find_bool_lit(arm.body) == Some(b0)
})
)
{
if !is_wild(last_arm.pat) {
return false;