Using `if let` to check for equality

It's not silly at all, but useful. For example, consider fn foo(Wrap(x): ...) or fn foo((Ok(x) | Err(x): ...).

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Yeah, so Rust managed to avoid the usual pitfall of if x = 42, so it shouldn't need Yoda conditions... and yet we still have them. I don't think that's good.

It would probably make sense to continue allowing it for code generation purposes. Suddenly failing to compile Yoda patterns would probably introduce a non-uniformity that would in turn require many macro authors to come up with special cases.

Oh, I didn't suggest we disallow it. We also allow if 42 == x, after all.

I just really dislike it being idiomatic for hand-written code.


I didn't mean the Yoda condition is good -- I was just amused to make the connection. Overall it's a natural edge case for pattern matching though. You can also write a constant let when it's irrefutable, like let () = println!(...);, which is only useful to statically assert the fact that it is constant.