Open Radar

 
Summary:
Given the following code:
```
import Foundation

let data = "hello, world".data(using: .utf8)!
let slices = data.split(separator: 0x2C)

let a = slices.map(Data.init)
let b = slices.map { Data($0) }
```
The compiler will fail on line 6 `.map(Data.init)` with the error `Ambiguous use of 'init'`. However, it succeeds on line 7 which is using the same initializer:
`public init<S>(_ elements: S) where S : Sequence, S.Element == UInt8`.

Steps to Reproduce:
1. Open the attached Playground
2. Observe that it fails to build with an error on line 6 `Ambiguous use of 'init'`
3. Comment out line 6
4. Observe that the Playground build succeeds

Expected Results:
That the compiler can disambiguate `.map(Data.init)` which is:
`public init<S>(_ elements: S) where S : Sequence, S.Element == UInt8`

Actual Results:
The compiler fails to disambiguate `.map(Data.init)`.

Version/Build:
Xcode 10 Beta 4 (10L213o)