relates to:

• SR-10259 ExpressibleByStringLiteral masks an initializer without any warning in Swift 5.

Issue Description:

Steps to reproduce

Note: This issue affects the Swift-4 mode of the Swift 5 compiler.

1. Execute the following code sample using both the Swift 4 compiler, and the Swift 5 compiler in Swift-4 compatibility mode:

struct TimeOfDay: ExpressibleByStringLiteral {
    init(_ string: String) {
        print("using init(_:)")
    }

    init(stringLiteral: String) {
        print("using init(stringLiteral:)")
    }
}

TimeOfDay.init("00:00")
TimeOfDay("00:00")

Expected result

The code should behave the same in both.

Actual result

In Swift 4, the output is:

using init(_:)
using init(_:)

In Swift-4 compatibility mode, the output is:

using init(_:)
using init(stringLiteral:)

Discussion

I understand that this change in behavior is the result of SE-0213. But, I think that change was only supposed to affect Swift 5 mode.

See this thread on the Swift forums.