[swift-evolution] [Discussion] Enforce argument labels on tuples

[Adrian Zubarev]

I would like to discuss about the following topic.

Wouldn't it be better to enforce argument labels on tuples types, if the tuple type defines them?

```swift

func foo(tuple: (a: Int, b: Int)) { /* do something */ }

let test1 = (10, 100)
let test2: (a: Int, c: Int) = test
let test3: (Int, Int) = test2

foo(test1)
foo(test3)

/*
cannot convert value of type '(a: Int, c: Int)' 
to expected argument type '(a: Int, b: Int)'
*/
foo(test2) 

```

Function `foo` awaits a tuple of type `(a: Int, b: Int)` but `test1` and `test3` are both just of type `(Int, Int)`.
As expected `test2` will raise an error because it has indeed a wrong type `(a: Int, c: Int)`.

I'd suggest to enforce argument labeling on tuple types for better readability, because wasn't it the idea behind labels inside tuples?

`foo(test1)` should raise an error `cannot convert value of type '(Int, Int)' to expected argument type '(a: Int, b: Int)'` as long as `test1` is not written like `let test1 = (a: 10, b: 100)` or `let test1: (a: Int, b: Int) = (a: 10, b: 100)`

This will impact current codebase if you used labels but provided tuples without labels like the example above. The migrator could solve this by providing labels automatically to tuples where this error occurs.

I'm not good at writing proposals for the GitHub repository at all, so if the community likes this idea, I'd be glad to see some help for this little proposal.

-- 
Adrian Zubarev
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