Suggest changing if let Some(3) = x to if x == Some(3)

[adamchalmers]

What it does

I was mentoring a new Rust programmer on my team, and he was a bit confused by if let. The root of his confusion was that he thought if let is used to introduce a binding. I agreed with him! But then he showed me a case where you can use if let without binding:

if let Some(3) = x {
   println!("it's true);
}

I told him, "yeah, if I saw that in code review, I would suggest using if x == Some(3) instead.

Categories (optional)

• Kind: style

What is the advantage of the recommended code over the original code

I think it's simpler, it uses a more standard language construct. You're just evaluating a boolean condition. IMO you should only use if let if you're actually trying to pattern match, but simply checking equality doesn't require pattern matching!

Drawbacks

This is basically just a generalization of redundant_pattern_matching, so it might have the same problems with ordering which that lint has.

Example

if let Some(3) = x {
   println!("it's true);
}

Could be written as:

if x == Some(3) {
   println!("it's true);
}

[camsteffen]

I guess I'd call this needless_if_let. It's not terrible style, but I agree that == is better, more idiomatic. Another aspect of the issue is that it's a yoda condition. I think this qualifies for style, but I could also understand pedantic.

[camsteffen]

Duplicate of #1716