Missing "unused variable" warning when using a match guard

[nstoddard]

I tried this code:

fn main() {
    match Some(42) {
        Some(unused) if true => (),
        _ => (),
    }
}

I expected to see this happen: the compiler should warn that unused is unused.

Instead, this happened: the code compiles without any warnings, unless the if true part is removed.

Meta

rustc --version --verbose:

rustc 1.93.0 (254b59607 2026-01-19)
binary: rustc
commit-hash: 254b59607d4417e9dffbc307138ae5c86280fe4c
commit-date: 2026-01-19
host: x86_64-unknown-linux-gnu
release: 1.93.0
LLVM version: 21.1.8

[eggyal]

@rustbot claim

[theemathas]

This emitted a warning in 1.91.0, but not 1.92.0.

[mu001999]

Regression in ff6dc92, #142390

[apiraino]

Assigning priority (discussion on Zulip).

@rustbot label -I-prioritize +P-medium