That indeed has this bad message on 5.3 but on near master, I'm seeing

func returnSingle() throws -> String { 
  return"Swift" 
} 
func returnTuple() throws -> (String, String) { 
  return("Swift", "Five") 
} 

func returnTupleWithoutThrows() -> (String, String) { 
  return("Swift", "Five") 
} 

func test() { 
   let test0 = try? returnSingle()
   print(test0 ?? "") 
   let tuple = try? returnTuple() 
   //less standard way 
   let(test1, test2) = returnTupleWithoutThrows() 
   let(test3, test4) = try? returnTuple() //error: value of optional type '(String, String)?' not unwrapped; did you mean to use 'try!' or chain with '?'?
}

Which to me seems correct ...

Comment by Nikhil (JIRA)

@LucianoPAlmeida

Okay, but any idea why the compiler doesn't complain for below two statements

let test0 = try? returnSingle()
 let tuple = try? returnTuple()

But does so for

let(test3, test4) = try? returnTuple() //error: value of optional type '(String, String)?' not unwrapped; did you mean to use 'try!' or chain with '?'?

I am not sure if they are consistent.

I think that is because a `tuple` variable is allowed to be inferred as `(String, String)?` and the same for the test0 which is also allowed to be inferred as `String?`. But in the example ` let(test3, test4) = try? returnTuple()` it cannot be an optional type because in order to destructure and assign each element to test3 and test4 it has to be guaranteed always to be a compatible tuple type. Think of it that way, what will you expect from value of test3 and test4 if `try? returnTuple()` is `nil`? That is the same for a case like bellow where a `returnTupleWithoutThrows` returns an optional tuple

func returnTupleWithoutThrows() -> (String, String)? {
  return("Swift", "Five")
}

func test() {
  let(test1, test2) = returnTupleWithoutThrows()//error: value of optional type '(String, String)?' not unwrapped; did you mean to use 'try!' or chain with '?'?
}

Note that assume test3 and test4 will be both `nil` if `try? returnTuple()` is `nil` would be incorrect because `(String?, String?)` it is not equivalent to `(String, String)?` That is why I think optional tuples are not allowed in this case 🙂

Comment by Nikhil (JIRA)

@LucianoPAlmeida Ok. Thanks for the explanation, I get it now. We can close this. You said near master has this fixed, please tell me where can I check this.

I did run the compiler on a test file that I was running for an issue I was working on with // RUN: %target-typecheck-verify-swift

But normally https://swift.godbolt.org you can easily check this without having to download and install the whole toolchain, or you can download the toolchain onn https://swift.org/download/#snapshots

Comment by Nikhil (JIRA)

@LucianoPAlmeida thank you for the info.