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Auto merge of #9496 - yotamofek:never_loop_let_else, r=Jarcho

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[`never_loop`]: Fix FP with let..else statements.

Fixes #9356

This has been bugging me for a while, so I thought I'd take a stab at it! I'm completely uncertain about the quality of my code, but I think it's an alright start, so opening this PR to get some feedback from more experienced clippy people :)

changelog: [`never_loop`]: Fix FP with let..else statements
This commit is contained in:
bors 2022-09-23 16:06:49 +00:00
commit ff65eec801
3 changed files with 71 additions and 20 deletions
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27
tests/ui/never_loop.rs
View file

@ -1,3 +1,4 @@
#![feature(let_else)]
#![allow(
clippy::single_match,
unused_assignments,
@ -203,6 +204,32 @@ pub fn test17() {
};
}
// Issue #9356: `continue` in else branch of let..else
pub fn test18() {
let x = Some(0);
let y = 0;
// might loop
let _ = loop {
let Some(x) = x else {
if y > 0 {
continue;
} else {
return;
}
};
break x;
};
// never loops
let _ = loop {
let Some(x) = x else {
return;
};
break x;
};
}
fn main() {
test1();
test2();

33
tests/ui/never_loop.stderr
View file

@ -1,5 +1,5 @@
error: this loop never actually loops
--> $DIR/never_loop.rs:10:5
--> $DIR/never_loop.rs:11:5
|
LL | / loop {
LL | | // clippy::never_loop
@ -13,7 +13,7 @@ LL | | }
= note: `#[deny(clippy::never_loop)]` on by default
error: this loop never actually loops
--> $DIR/never_loop.rs:32:5
--> $DIR/never_loop.rs:33:5
|
LL | / loop {
LL | | // never loops
@ -23,7 +23,7 @@ LL | | }
| |_____^
error: this loop never actually loops
--> $DIR/never_loop.rs:52:5
--> $DIR/never_loop.rs:53:5
|
LL | / loop {
LL | | // never loops
@ -35,7 +35,7 @@ LL | | }
| |_____^
error: this loop never actually loops
--> $DIR/never_loop.rs:54:9
--> $DIR/never_loop.rs:55:9
|
LL | / while i == 0 {
LL | | // never loops
@ -44,7 +44,7 @@ LL | | }
| |_________^
error: this loop never actually loops
--> $DIR/never_loop.rs:66:9
--> $DIR/never_loop.rs:67:9
|
LL | / loop {
LL | | // never loops
@ -56,7 +56,7 @@ LL | | }
| |_________^
error: this loop never actually loops
--> $DIR/never_loop.rs:102:5
--> $DIR/never_loop.rs:103:5
|
LL | / while let Some(y) = x {
LL | | // never loops
@ -65,7 +65,7 @@ LL | | }
| |_____^
error: this loop never actually loops
--> $DIR/never_loop.rs:109:5
--> $DIR/never_loop.rs:110:5
|
LL | / for x in 0..10 {
LL | | // never loops
@ -82,7 +82,7 @@ LL | if let Some(x) = (0..10).next() {
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: this loop never actually loops
--> $DIR/never_loop.rs:157:5
--> $DIR/never_loop.rs:158:5
|
LL | / 'outer: while a {
LL | | // never loops
@ -94,12 +94,25 @@ LL | | }
| |_____^
error: this loop never actually loops
--> $DIR/never_loop.rs:172:9
--> $DIR/never_loop.rs:173:9
|
LL | / while false {
LL | | break 'label;
LL | | }
| |_________^
error: aborting due to 9 previous errors
error: this loop never actually loops
--> $DIR/never_loop.rs:224:13
|
LL | let _ = loop {
| _____________^
LL | | let Some(x) = x else {
LL | | return;
LL | | };
LL | |
LL | | break x;
LL | | };
| |_____^
error: aborting due to 10 previous errors