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Do raise a same-arms warning when the two arms are separated by an arm with a guard, fix #1996.

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laurent
2017-12-01 19:25:43 +00:00
parent 876d6d8c43
commit 904f27a2ea
4 changed files with 21 additions and 35 deletions
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34
clippy_lints/src/copies.rs
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@@ -178,22 +178,26 @@ fn lint_same_cond(cx: &LateContext, conds: &[&Expr]) {
/// 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()
};
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])
};
if let ExprMatch(_, ref arms, MatchSource::Normal) = expr.node {
if let Some((i, j)) = search_same(arms, hash, eq) {
let hash = |&(_, arm): &(usize, &Arm)| -> u64 {
let mut h = SpanlessHash::new(cx);
h.hash_expr(&arm.body);
h.finish()
};
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])
};
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,