Rule request: Unneeded parentheses in closure argument

[marcelofabri]

// good
let foo = { (bar: Int) in
    print(bar)
}

// bad
call(arg: { (bar2) in

})

We could use a regex (\{\s*\([^:]+\)\s*in) to do it and also check for source.lang.swift.decl.var.parameter without a key.typename.

Stole the idea and regex from @keith

[marcelofabri]

Maybe this should have an option to allow the parentheses when the return type is explicit and there are more than one parameter? e.g.

ruleList.list.flatMap { (identifier, rule) -> [(String, String)] in
   return rule.description.deprecatedAliases.map { ($0, identifier) }
}

[Jeehut]

Emphasis on "and", I'd say. See my examples in my request (#1583) to see what I mean what I'd expect to be accepted.