/// Implementation if `MATCH_SAME_ARMS`.
fn lint_match_arms(cx: &LateContext, expr: &Expr) {
- let hash = |arm: &Arm| -> u64 {
- let mut h = SpanlessHash::new(cx);
- h.hash_expr(&arm.body);
- h.finish()
- };
+ if let ExprMatch(_, ref arms, MatchSource::Normal) = expr.node {
+ let hash = |&(_, arm): &(usize, &Arm)| -> u64 {
+ let mut h = SpanlessHash::new(cx);
+ h.hash_expr(&arm.body);
+ h.finish()
+ };
- let eq = |lhs: &Arm, rhs: &Arm| -> bool {
- // Arms with a guard are ignored, those can’t always be merged together
- lhs.guard.is_none() && rhs.guard.is_none() &&
- SpanlessEq::new(cx).eq_expr(&lhs.body, &rhs.body) &&
- // all patterns should have the same bindings
- bindings(cx, &lhs.pats[0]) == bindings(cx, &rhs.pats[0])
- };
+ let eq = |&(lindex, lhs): &(usize, &Arm), &(rindex, rhs): &(usize, &Arm)| -> bool {
+ let min_index = usize::min(lindex, rindex);
+ let max_index = usize::max(rindex, rindex);
+ // Arms with a guard are ignored, those can’t always be merged together
+ // This is also the case for arms in-between each there is an arm with a guard
+ (min_index..=max_index).all(|index| arms[index].guard.is_none()) &&
+ SpanlessEq::new(cx).eq_expr(&lhs.body, &rhs.body) &&
+ // all patterns should have the same bindings
+ bindings(cx, &lhs.pats[0]) == bindings(cx, &rhs.pats[0])
+ };
- if let ExprMatch(_, ref arms, MatchSource::Normal) = expr.node {
- if let Some((i, j)) = search_same(arms, hash, eq) {
+ let indexed_arms: Vec<(usize, &Arm)> = arms.iter().enumerate().collect();
+ if let Some((&(_, i), &(_, j))) = search_same(&indexed_arms, hash, eq) {
span_lint_and_then(
cx,
MATCH_SAME_ARMS,
| ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
-error: this `match` has identical arm bodies
- --> $DIR/matches.rs:292:18
- |
-292 | Ok(_) => println!("ok"),
- | ^^^^^^^^^^^^^^
- |
-note: same as this
- --> $DIR/matches.rs:290:18
- |
-290 | Ok(3) => println!("ok"),
- | ^^^^^^^^^^^^^^
-note: consider refactoring into `Ok(3) | Ok(_)`
- --> $DIR/matches.rs:290:18
- |
-290 | Ok(3) => println!("ok"),
- | ^^^^^^^^^^^^^^
- = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
-
error: this `match` has identical arm bodies
--> $DIR/matches.rs:298:29
|