`prefer_type_checking` and optional types violation

[cyberowl]

New Issue Checklist

• I've Updated SwiftLint to the latest version.
• I've searched for existing GitHub issues.

Bug Description

The following code causes false positive prefer_type_checking violation:

let value: String? = nil
print(value as Any? != nil) // -> false

Let's try fix it:

swiftlint . --fix

Now we got this:

let value: String? = nil
// xcodebuild warning: `'is' test is always true`
print(value is Any?) // -> now true, that's not expected

Environment

• SwiftLint version: 0.57.0
• Xcode version: 16.0 (16A242d)
• Installation method used: Homebrew
• Configuration file: None

[mildm8nnered]

At first I thought we should just ignore SomeType? completely, but actually I wonder if we should be triggering on as at all, as opposed to as??

That would fix this case.

someVar as? SomeType? != nil would still get caught, but we could ignore SomeType? as well

[mildm8nnered]

So I think this case will also be problematic

let x: String? = nil
print(x as String? != nil) // false
print(x is String?) // true

So I think we want to exclude the OptionalTypeSyntax cases as well