never_loop removes label that the replaced loop was attached to (outer label) #15350
Description
followup to #15007 I guess ?
Using the following flags
--force-warn clippy::never_loop
this code:
//@ run-pass
pub fn main() {
'foo: loop {
loop {
break 'foo;
}
}
'bar: for _ in 0..100 {
loop {
break 'bar;
}
}
'foobar: while 1 + 1 == 2 {
loop {
break 'foobar;
}
}
}caused the following diagnostics:
Checking _labeled-break v0.1.0 (/tmp/icemaker_global_tempdir.0gE5D6KlClUx/icemaker_clippyfix_tempdir.hvDqeCsLHElq/_labeled-break)
warning: this loop never actually loops
--> src/main.rs:4:5
|
4 | / 'foo: loop {
5 | | loop {
6 | | break 'foo;
7 | | }
8 | | }
| |_____^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
= note: requested on the command line with `--force-warn clippy::never-loop`
warning: this loop never actually loops
--> src/main.rs:5:9
|
5 | / loop {
6 | | break 'foo;
7 | | }
| |_________^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
warning: this loop never actually loops
--> src/main.rs:10:5
|
10 | / 'bar: for _ in 0..100 {
11 | | loop {
12 | | break 'bar;
13 | | }
14 | | }
| |_____^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
help: if you need the first element of the iterator, try writing
|
10 - 'bar: for _ in 0..100 {
10 + if let Some(_) = (0..100).next() {
|
warning: this loop never actually loops
--> src/main.rs:11:9
|
11 | / loop {
12 | | break 'bar;
13 | | }
| |_________^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
warning: this loop never actually loops
--> src/main.rs:16:5
|
16 | / 'foobar: while 1 + 1 == 2 {
17 | | loop {
18 | | break 'foobar;
19 | | }
20 | | }
| |_____^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
warning: this loop never actually loops
--> src/main.rs:17:9
|
17 | / loop {
18 | | break 'foobar;
19 | | }
| |_________^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
warning: `_labeled-break` (bin "_labeled-break") generated 6 warnings
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.42s
However after applying these diagnostics, the resulting code:
//@ run-pass
pub fn main() {
'foo: loop {
loop {
break 'foo;
}
}
if let Some(_) = (0..100).next() {
loop {
break 'bar;
}
}
'foobar: while 1 + 1 == 2 {
loop {
break 'foobar;
}
}
}no longer compiled:
Checking _labeled-break v0.1.0 (/tmp/icemaker_global_tempdir.0gE5D6KlClUx/icemaker_clippyfix_tempdir.hvDqeCsLHElq/_labeled-break)
error[E0426]: use of undeclared label `'bar`
--> src/main.rs:12:19
|
12 | break 'bar;
| ^^^^ undeclared label `'bar`
For more information about this error, try `rustc --explain E0426`.
error: could not compile `_labeled-break` (bin "_labeled-break") due to 1 previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `_labeled-break` (bin "_labeled-break" test) due to 1 previous error
Version:
rustc 1.90.0-nightly (f32b23204 2025-07-26)
binary: rustc
commit-hash: f32b23204a0efe2fe8383ed4be1a30b56c1bbf94
commit-date: 2025-07-26
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.8