False positives and false negatives with unused_optional_binding

[drodriguez]

// Should not trigger, but triggers
if case .some(_) = self {
}

// Should trigger, but doesn’t
if case .some(let _) = self {
}

Seems that any usage of case is ignored.

Reviewing the rule code, the regular expressions used are quite broad and don’t even check for let being or not there.

Something like the following almost get it right:

        let underlineOutsideParenthesis = "(?<=let\\s)_\\s*="
        let underlineInsideParenthesis = "(?<=let\\s)\\((\\s*[_,]\\s*)+\\)"
        let pattern = "(("  + underlineOutsideParenthesis + ")|(" + underlineInsideParenthesis + "))"

But it doesn’t catch the case .some(let _) case.

/cc @marcelofabri

[crayment]

Getting false positive a lot for code like:

guard case .dictionary(_) = json else {

[marcelofabri]

@drodriguez Can you send a PR fixing the false positives? I think that is more important than catching the case .some(let _) case for now.

We can then create another issue just for that and address in the future.

[drodriguez]

PR sent with the full solution (hopefully): #1396

[alejandro-isaza]

I'm getting a false positive with

if let point = state.find({ _ in true }) { ... }

[drodriguez]

I think the fix in #1396 will avoid the false positive in @Aleph7 example. When I have a moment I will add it to the examples of that PR and check for sure.