Rule Request: `guard self` (vs weakSelf, strongSelf)

[freak4pc]

New Issue Checklist

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

New rule request

1. Why should this rule be added?

Since Swift 4.2 we can now do guard let self = self instead of guard let strongSelf, guad let weakSelf, guard let 'self' and all other sort of oddities. I'd like to enforce that.

2. Provide several examples of what would and wouldn't trigger violations.

Trigger:

if let `self` = self
guard let `self` = self
guard let strongSelf = self
guard let [anything not "self"] = self

Doesn't trigger:

if let self = self
guard let self = self
guard let self = [anytime this is self]

3. Should the rule be configurable, if so what parameters should be configurable?
   I don't think so.

4. Should the rule be opt-in or enabled by default? Why?
   Opt-in

[jpsim]

Thanks for the suggestion! I think this should be configurable on the rebinding identifier. There are still issues with Swift 4.2+ when rebinding self to self, especially around lldb (see SR-6156). For this reason, some projects have adopted a pattern to always rebind self to something specifically different, in Lyft's case that's guard let this = self.

[freak4pc]

Yup, that makes sense :)

[lennartstolz]

I do feel like a grave desecrator - but I'd still love to see this rule becoming part of SwiftLint.

Especially because in the last ~3 yrs it almost became the standard in most codebases to use:

guard let self = self else { ... }

and the issue mentioned by @jpsim is also resolved by now. ✅

@marcelofabri : Do you think it's a valuable addition to SwiftLint? Is it "straightforward" to be implemented?
If so: I volunteer to implement it.

[dwirandytlvk]

Any update related to this?

[jpsim]

Adding a rule to do this in #4146