[Pitch] Predecessor and successor operators for integers

[bbrk24]

@x-sheep

which performs just as well as any native solution (short-circuiting, correct operator precedence etc.)

Assuming it's just

infix operator ?= : AssignmentPrecedence

func ?= <T>(lhs: inout T?, rhs: @autoclosure () -> T?) {
  if lhs == nil {
    lhs = rhs()
  }
}

This still triggers willSet/didSet listeners when it does nothing: SwiftFiddle - Swift Online Playground