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Description
Summary
needless_match is warned, while the suggestion would really change the execution logic.
Discovered in servo/servo#36908 (comment)
Lint Name
needless_match
Reproducer
I tried this code:
fn side_effect() {
println!("Side effect!");
}
fn t() -> Result<i32, &'static str> {
if 5 > 3 { Ok(3) } else { Err("Error") }
}
fn logic() -> Result<i32, &'static str> {
let x = match t() {
Ok(v) => Ok(v),
err @ Err(_) => return err,
};
// Only when Ok
side_effect();
x
}
fn main() {
let _ = logic();
}I saw this happen:
warning: this match expression is unnecessary
--> src\main.rs:10:13
|
10 | let x = match t() {
| _____________^
11 | | Ok(v) => Ok(v),
12 | | err @ Err(_) => return err,
13 | | };
| |_____^ help: replace it with: `t()`
I expected to see this happen:
No Warning. As the suggestion would change the execution logic.
Version
rustc 1.85.1 (4eb161250 2025-03-15)
binary: rustc
commit-hash: 4eb161250e340c8f48f66e2b929ef4a5bed7c181
commit-date: 2025-03-15
host: x86_64-pc-windows-msvc
release: 1.85.1
LLVM version: 19.1.7
Additional Labels
No response