if_same_then_else should not trigger when one branch is "if let <pattern> = thing"

[DanielT]

Lint name: if_same_then_else

I've simplified my code some, but it basically looks like this

if let Some(MyEnum::Variant(_)) = value {
    cleanup_some_state();
} else if other_condition {
    cleanup_some_state();
} else {
    // do more work
}

Clippy generates the if_same_then_else diagnostic for this code.
As a matter of fact, I would love to unify the two identical branches, but as far as I know, I cannot add any other conditions to the "if let".

There should be no message from clippy here, since writing the code the way clippy suggests is not possible

Meta

Rust version (rustc -Vv):

rustc 1.57.0-nightly (a8f2463c6 2021-10-09)
binary: rustc
commit-hash: a8f2463c68a6532d74a13ec402ec5b513e4e2726
commit-date: 2021-10-09
host: x86_64-pc-windows-msvc
release: 1.57.0-nightly
LLVM version: 13.0.0

[PatchMixolydic]

It's possible to rewrite this code like this:

if matches!(value, Some(MyEnum::Variant(_))) || other_condition {
    cleanup_some_state();
} else {
    // do more work
}

It might be possible to emit a suggestion to this effect. Note that this will work even if a new binding is introduced since the binding couldn't actually be used aside from it being dropped (otherwise, the two blocks would be different, so this lint wouldn't trip in the first place). I believe drop order should still be the same so long as any bindings created in the if let arm remain intact.

[DanielT]

I wasn't even aware that matches! existed. It definitely solves my problem.
Very interesting, thanks!

[camsteffen]

Duplicate of #7579