Casting AnyObject to closure with noncopyable parameter makes compiler fatalError

struct T: ~Copyable {
var a: AnyObject!
_ = a as! ((Int, borrowing T) -> Void)

compiler(Swift version 5.9.2) says:

:0: error: copy of noncopyable typed value. This is a compiler bug. Please file a bug with a small example of the bug

error: fatalError

Hi, good find!

Usually someone who works on this area will see posts here, but to help track the problem you can file a bug with this example over at Issues · apple/swift · GitHub