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Merge pull request #2254 from LaurentMazare/master

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Avoid the MATCH_SAME_ARMS warning when two arms are separated by an arm with a guard
This commit is contained in:
Oliver Schneider 2017-12-01 21:07:11 +01:00 committed by GitHub
commit 6bb661b8c8
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3 changed files with 20 additions and 34 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(lindex, 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,

2
tests/ui/matches.rs
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@ -285,7 +285,7 @@ fn match_wild_err_arm() {
Err(_) => println!("err")
}
// this is a current false positive, see #1996
// this used to be a false positive, see #1996
match x {
Ok(3) => println!("ok"),
Ok(x) if x*x == 64 => println!("ok 64"),

18
tests/ui/matches.stderr
View File

@ -390,24 +390,6 @@ note: consider refactoring into `Ok(3) | 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: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
|