`@available` doesn’t affect literal initialization

[davdroman]

Describe the bug
When a literal initializer is marked with an availability annotation, it's seemingly ignored by the compiler at the point of use, unless the initializer is used explicitly.

Steps To Reproduce

struct Foo {
    let bar: String
}

@available(*, deprecated)
extension Foo: ExpressibleByStringLiteral {
    init(stringLiteral value: StringLiteralType) {
        self.bar = value
    }
}

let a: Foo = Foo(stringLiteral: "") // warning: 'init(stringLiteral:)' is deprecated
let b: Foo = "" // no warning

Expected behavior
Both assignments should cause a deprecation warning.

Note: every other availability status (e.g. unavailable) is also ignored.

Screenshots

[greenthings]

What I understand is that you deprecated stringLiteral the way initializes the bar.

But, why neither "a" nor "b" gives a warning and only "a" gives a warning?

If this is correct understanding, check this.

In the swift/Literals.md, you can find below.

The ExpressibleByStringLiteral Protocol

/// A type that can be initialized with a string literal.
///
/// The String and StaticString types conform to the
/// ExpressibleByStringLiteral protocol.

You can initialize a variable or constant of either of these types using a string literal of any length.

///_
/// let picnicGuest = "Deserving porcupine"
///

So, Even if you deprecated it, It can be initialized with a string literal like "", "a", "b" and so on.

I hope it will help you.

[greenthings]

Reference)
https://github.com/apple/swift/blob/main/docs/Literals.md

[davdroman]

Thank you for such a quick turnaround @LucianoPAlmeida! 👏