Swift 6 rethrows forcing "try" for a non-throwable closure

[brustolin]

Description

The following code snippet is not compiling under Swift 6, it works fine in Swift 5:

extension UIView{
   func addSubviews(_ views : [UIView]) {
      views.forEach(self.addSubview(_:))
   }
}

This is the workaround that works

func addSubviews(_ views : [UIView]) {
    views.forEach({ self.addSubview($0) })
}

Which is pretty much the same thing.

Environment

swift-driver version: 1.115
Apple Swift version 6.0 (swiftlang-6.0.0.9.10 clang-1600.0.26.2)
Target: arm64-apple-macosx15.0

[Kyle-Ye]

I can reproduce it with AppKit or UIKit's addSubview.

But a custom (Int)->Void will not trigger the bug.

Also using Swift 6 compiler + Swift 5 Language mode will not trigger the bug.

import AppKit

func square(_ value: Int) -> Void {
    print(value * value)
}

@MainActor
func demo() {
    let array = [1, 2]
    array.forEach(square(_:))
    
    let root = NSView()
    let views: [NSView] = []
    views.forEach(root.addSubview(_:))
}