Swiftlint: unused_import: False positive when using `is` comparison

[rebello95]

When running the unused_import rule, the following triggers a false-positive:

XCTAssertTrue(someFoo is Foo)

In this case, the import Foo is flagged as unused, even though it's used within the comparison statement.

[jpsim]

Worth noting that the following does not trigger the same false positive:

XCTAssertNotNil(someFoo as? Foo)

[a-25]

@rebello95: Hello, Michael.
I tried to reproduce this on version 0.35 but I couldn't. Here is the command:
swiftlint analyze --compiler-log-path <path-to-xcodebuild.log> --config <path-to-testconfig.yml> <path-to-SwiftlintTest.xcodeproj>

SwiftlintTest project:
SwiftlintTest.zip

contents of testConfig.yml:

analyzer_rules:
  - unused_import

Does this bug reproduce now? If it does, could you post full example of your code to reproduce it?

[rebello95]

Thanks for taking a look.

I ran your project locally but was getting the following output after adding a .swiftlint.yml file:

mrebello-mbp151:SwiftlintTest mrebello$ swiftlint analyze --compiler-log-path /Users/mrebello/Downloads/output.txt --config /Users/mrebello/Downloads/SwiftlintTest/.swiftlint.yml /Users/mrebello/Downloads/SwiftlintTest/SwiftlintTest.xcodeproj
Loading configuration from '/Users/mrebello/Downloads/SwiftlintTest/.swiftlint.yml'
Analyzing Swift files at paths /Users/mrebello/Downloads/SwiftlintTest/SwiftlintTest.xcodeproj
No lintable files found at paths: '/Users/mrebello/Downloads/SwiftlintTest/SwiftlintTest.xcodeproj'

However, I did read through the code in the AppDelegate, and it looks like you're explicitly instantiating the type. I believe this should repro the issue:

import UIKit
import SwiftlintTestLibrary

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        let someFoo: Any = ""
        XCTAssertTrue(someFoo is SwiftlintTestLibrary)
        return true
    }

    private func XCTAssertTrue(_ isFoo: Bool) {
        print("\(isFoo)")
    }
}

[a-25]

@rebello95: tried to use your example, but still no errors.
You are using swiftlint 0.35, aren't you? Could you attach your .swiftlint.yml file or more exact code sample?

[rebello95]

Very weird, I'm now unable to reproduce this issue. I'll re-open this issue if I come across this again and am able to repro. Thanks for investigating.

[jpsim]

This seems to be related to SR-12047

[keith]

Sounds like this is fixed in 5.2 https://bugs.swift.org/browse/SR-8616