| // RUN: %target-swift-frontend -O -emit-sil %s | %FileCheck %s | |
| // Check that the optimizer does not crash. | |
| public class Base { | |
| @inline(never) | |
| final func next() -> Base? { | |
| return self | |
| } | |
| } | |
| public class Derived : Base {} | |
| // CHECK: sil {{.*}}testit | |
| public func testit(_ x: Base?) -> Derived? { | |
| var i: Base? = x | |
| while (i is Derived) == false && i != nil { | |
| i = i?.next() | |
| } | |
| return i as? Derived | |
| } | |