Summary
match_same_arms appears to consider two arms the same if their bodies are references to different associated constants that happen to evaluate the same.
Lint Name
match_same_arms
Reproducer
I tried this code:
#![warn(clippy::match_same_arms)]
fn main() {
trait Foo {
const X: u8;
}
impl Foo for u8 {
const X: u8 = 2;
}
impl Foo for i8 {
const X: u8 = 2;
}
match true {
false => u8::X,
true => i8::X,
};
}I saw this happen:
warning: these match arms have identical bodies
--> test.rs:14:9
|
14 | false => u8::X,
| ^^^^^^^^^^^^^^
15 | true => i8::X,
| ^^^^^^^^^^^^^
|
= help: if this is unintentional make the arms return different values
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#match_same_arms
note: the lint level is defined here
--> test.rs:1:9
|
1 | #![warn(clippy::match_same_arms)]
| ^^^^^^^^^^^^^^^^^^^^^^^
help: otherwise merge the patterns into a single arm
|
14 - false => u8::X,
15 - true => i8::X,
14 + false | true => i8::X,
|
I expected to see this happen: no warning
Version
rustc 1.94.0 (4a4ef493e 2026-03-02)
binary: rustc
commit-hash: 4a4ef493e3a1488c6e321570238084b38948f6db
commit-date: 2026-03-02
host: aarch64-apple-darwin
release: 1.94.0
LLVM version: 21.1.8
This appears to be a regression between 1.91.1 and 1.92.0
Additional Labels
No response
Summary
match_same_armsappears to consider two arms the same if their bodies are references to different associated constants that happen to evaluate the same.Lint Name
match_same_arms
Reproducer
I tried this code:
I saw this happen:
I expected to see this happen: no warning
Version
This appears to be a regression between 1.91.1 and 1.92.0
Additional Labels
No response