Rule Request: `Bool` variable naming

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

New rule request

It is a convention to prefix Bool variables with a verb to indicate the type - usually is/are, but there could be others. Examples include UIView.isHidden, UIDeviceOrientation.isPortrait or the standard library's Collection.isEmpty.

Triggering examples:

var flipped = false

var changes = true

let empty: Bool

Non-triggering examples:

var isFlipped = false

var hasChanges = true

let isEmpty: Bool

The rule should have a list of prefixes that are allowed by default and the ability to specify more. From my experience, I'd start with is, are, has, should, can, will, did.

The rule should probably be opt-in.

I'm posting this first in case there are any red flags - I don't want to spend time developing this only to be told later that the rule won't be merged 🙂

No files, tests, or entry points are named. Start by reviewing SwiftLint's existing rule implementations and configuration conventions, then determine how an opt-in Bool-naming rule and configurable prefixes should fit them. Done means the proposed behavior, defaults, configuration, and triggering and non-triggering cases are covered and accepted.