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Improve dead_code lint to detect unused structs which implement private traits #122361
Description
Code
#![deny(dead_code)]
struct T;
struct UnusedT1;
struct UnusedT2;
pub trait PubTrait {
fn foo(&self) -> Self;
}
impl PubTrait for T {
fn foo(&self) -> Self { T }
}
impl PubTrait for UnusedT1 {
fn foo(&self) -> Self { UnusedT1 }
}
trait PriTrait {
fn foo(&self) -> Self;
}
impl PriTrait for T {
fn foo(&self) -> Self { T }
}
impl PriTrait for UnusedT2 {
fn foo(&self) -> Self { UnusedT2 }
}
fn main() {
let t = T;
let _t = <T as PubTrait>::foo(&t);
let _t = <T as PriTrait>::foo(&t);
}Current output
error: struct `UnusedT1` is never constructed
--> src/main.rs:4:8
|
4 | struct UnusedT1;
| ^^^^^^^^
|
note: the lint level is defined here
--> src/main.rs:1:9
|
1 | #![deny(dead_code)]
| ^^^^^^^^^
error: could not compile `playground` (bin "playground") due to 1 previous errorDesired output
error: struct `UnusedT1` is never constructed
--> src/main.rs:4:8
|
4 | struct UnusedT1;
| ^^^^^^^^
|
note: the lint level is defined here
--> src/main.rs:1:9
|
1 | #![deny(dead_code)]
| ^^^^^^^^^
error: struct `UnusedT2` is never constructed
--> src/main.rs:5:8
|
5 | struct UnusedT2;
| ^^^^^^^^
error: could not compile `playground` (bin "playground") due to 2 previous errorsRationale and extra context
No response
Other cases
No response
Rust Version
Rustc 1.78.0-nightly (2024-03-11 4a0cc881dcc4d800f106)Anything else?
No response
Activity
mu001999 commentedon Mar 12, 2024
@rustbot claim
krtab commentedon Mar 12, 2024
Maybe you can get inspiration from #119552, especially if you end up having to fix previously undetected errors in multiple places in rustc.
mu001999 commentedon Mar 12, 2024
Thanks for your suggestion, but I think this just needs to extend #121752 ;)
Rollup merge of rust-lang#122382 - mu001999:dead_code/enhance, r=petr…
Unrolled build for rust-lang#122382