Code

#![feature(let_chains)]

fn max() -> usize {
    42
}

fn main() {
    if let mx = max() && mx < usize::MAX {
        // ...
    }
}

Current output

warning: leading irrefutable pattern in let chain
 --> src/main.rs:7:8
  |
7 |     if let mx = max() && mx < usize::MAX {
  |        ^^^^^^^^^^^^^^
  |
  = note: this pattern will always match
  = help: consider moving it outside of the construct
  = note: `#[warn(irrefutable_let_patterns)]` on by default

Desired output

(no warning)

Rationale and extra context

This code naturally expresses "please call that function and then do something if the return value satisfies a condition". Putting the let binding outside the if would be bad as then it remains in scope after the if, which is not the intent. I could wrap it in an extra layer of curly braces but that increases the overall indentation level.

I think this warning should never trigger for let chains.

Other cases

Rust Version

current nightly

Anything else?

No response