Swift date(byAdding:to:) returns nil for trivial calculation in REPL

Question

I expect this to return a Date object representing the time one hour from now:

Calendar.current.date(b         


        

Answer 1

This is a bug in the Swift REPL, see

• SR-11593 REPL incorrectly reports URL as nil
• SR-12172 Description of Date? expression is printed as nil even when non-nil

It affects both optional and non-optional values of some Swift overlay types (such as Date, Calendar, URL). Example:

$ swift
Welcome to Apple Swift version 5.1.3 (swiftlang-1100.0.282.1 clang-1100.0.33.15).
Type :help for assistance.
  1> import Foundation
  2>  
  3> let d1 = Date()
d1: Date = {}
  4> let d2: Date? = Date()
d2: Date? = nil
  5> let url = URL(string: "https://www.google.com")
url: URL? = nil

As a workaround you can print the values:

  7> print(d1)
2020-03-03 10:17:00 +0000
  8> print(d2)
Optional(2020-03-03 10:17:07 +0000)
  9> print(url)
Optional(https://www.google.com)