single_match shouldn't warn when matching on an explicit error type

[stevenengler]

Summary

In the following code, I think the clippy suggestion is worse than the original code. The original code is explicitly matching on the error "NotFoundError". If the error return type of foo were to change in the future (for example to become an enum with multiple error variants, or to become something like "NotAuthenticatedError" instead), we'd want this match statement to fail to build so that we could update it for the new error type and make sure we're handling it correctly. The clippy suggestion wants us to remove the error matching completely.

I think it would be nicer if this lint only triggered when the error type is omitted completely, for example Err(_) => {}.

Lint Name

single_match

Reproducer

I tried this code:

struct NotFoundError;

fn bar() -> Result<(), NotFoundError> { todo!() }

fn main() {
    match bar() {
        Ok(()) => {},
        // don't need to do anything if not found
        Err(NotFoundError) => {},
    }
}

https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=421e3fe89d0da5e2685c435d43246689

I saw this happen:

warning: you seem to be trying to use `match` for destructuring a single pattern. Consider using `if let`
  --> src/main.rs:6:5
   |
6  | /     match bar() {
7  | |         Ok(()) => {},
8  | |         // don't need to do anything if not found
9  | |         Err(NotFoundError) => {},
10 | |     }
   | |_____^ help: try: `if let Ok(()) = bar() {}`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#single_match
   = note: `#[warn(clippy::single_match)]` on by default

I expected to see this happen:

No warning.

Version

rustc 1.83.0-nightly (26b5599e4 2024-09-06)
binary: rustc
commit-hash: 26b5599e4d6ed2b45152c60493c1788c0a27533d
commit-date: 2024-09-06
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0

Additional Labels

No response