[swift-users] overloading methods where only difference is optional vs. non-optional type

[Phil Kirby]

2 down vote favorite
Original StackOverflow post:
https://stackoverflow.com/questions/46620311/overloading-methods-where-only-difference-is-optional-vs-non-optional-type
I was under the impression that swift can have overloaded methods that differ only in the type of object that the methods return. I would think that I could have two funcs with the same signature yet they differ in return type.
import Foundation

// ambiguous use of 'IsTextEmpty(text:)'
func IsTextEmpty(text : String?) -> Bool? {
return text?.isEmpty
}

func IsTextEmpty(text : String?) -> Bool {
  guard let text = text else {
    return true
  }

  return text.isEmpty
}

let text: String? = nil

if let empty = IsTextEmpty(text:"text") {
  print("Not Empty")
}

if IsTextEmpty(text: text) {
  print("Empty")
}
Here, both functions have the same input parameters but one func returns an optional Bool? and the other returns a Bool. In this case I get an error:
ambiguous use of 'IsTextEmpty(text:)'
If I change the name of one of the input parameters I no longer get the ambiguous error:
// Works
func IsTextEmpty(foo : String?) -> Bool? {
return foo?.isEmpty
}

func IsTextEmpty(text : String?) -> Bool {
  guard let text = text else {
    return true
  }

  return text.isEmpty
}

let text: String? = nil

if let empty = IsTextEmpty(foo:"text") {
  print("Not Empty")
}

if IsTextEmpty(text: text) {
  print("Empty")
}
Shouldn't the compiler detect that they are two distinct methods even though their return types are different, since an optional Bool? is a different type from a non-optional Bool?

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