Change argument label

[philipturner]

Why is this named bounds when it's position for other collection types? For example: https://github.com/apple/swift/blob/2696df4f22dbb37d19be132da36341de94960a30/stdlib/public/core/BidirectionalCollection.swift#L215

Will changing the argument label have any effects on third-party clients? I tried the following and it isn't possible:

print(RangeReplaceableCollection.subscript(bounds:)) // emits an error

extension RangeReplaceableCollection {
  // emits an error for "could not find `subscript(bounds:)` in scope"
  @derivative(of: subscript(bounds:))
  func foo() -> (value: Void, pullback: (Void) -> Void) {}
}

[CodaFi]

Yeah, looks like a copy-and-paste mistake. Interior argument labels are not ABI in subscripts and there is no source impact for altering them.

@swift-ci smoke test and merge