False positive in a loop that uses let/else #10085
Description
Summary
Using let/else rather than an alternative block of code doing the same thing causes clippy to think that a loop never actually loops.
Lint Name
clippy::never_loop
Reproducer
This repository demonstrates the problem:
https://github.com/shinypb/rust-clippy-loop-false-positive
I tried this code:
while let Ok(event) = receiver.recv() {
let ServiceEvent::ServiceResolved(info) = event else {
// We don't care about other events here
continue;
};
let Some(addr) = info.get_addresses().iter().next() else {
// No one should ever have zero addresses, but just in case...
continue;
};
let port = info.get_port();
return Ok((
info.get_fullname().to_string(),
format!("http://{addr}:{port}"),
));
}I saw this happen:
error: this loop never actually loops
--> src/main.rs:8:5
|
8 | / while let Ok(event) = receiver.recv() {
9 | | let ServiceEvent::ServiceResolved(info) = event else {
10 | | // We don't care about other events here
11 | | continue;
... |
21 | | ));
22 | | }
| |_____^
|
= note: `#[deny(clippy::never_loop)]` on by default
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#never_loop
error: could not compile `rust-clippy-loop-false-positive` due to previous error
Changing my code to avoid the let/else makes the problem go away (yes, this is a very gross way of doing that; I am just trying to have a minimal patch for the purposes of this example 😅 ):
- let Some(addr) = info.get_addresses().iter().next() else {
+ let mut addr = String::from("");
+ if let Some(addr_inner) = info.get_addresses().iter().next() {
+ // ...
+ addr.push_str(&addr_inner.to_string());
+ } else {Version
rustc 1.65.0 (897e37553 2022-11-02)
binary: rustc
commit-hash: 897e37553bba8b42751c67658967889d11ecd120
commit-date: 2022-11-02
host: aarch64-apple-darwin
release: 1.65.0
LLVM version: 15.0.0
Additional Labels
No response