Fix cast that is disallowed by SE-0054.

rudkx · rudkx · commit 6f94583ca9b7 · 2017-11-06T11:30:58.000-08:00
SE-0054 (Abolish ImplicitlyUnwrappedOptionalType) substantially reduced
the number of places that '!' can be used, but the implementation missed
certain cases like this one. That implementation is being overhauled to
catch all the illegal cases.
diff --git a/Foundation/NSKeyedArchiverHelpers.swift b/Foundation/NSKeyedArchiverHelpers.swift
@@ -29,7 +29,7 @@ internal class _NSKeyedArchiverUID : NSObject {
     }
 
     open override var hash: Int {
-        return Int(bitPattern: CFHash(_cfObject as CFTypeRef!))
+        return Int(bitPattern: CFHash(_cfObject as CFTypeRef?))
     }
     
     open override func isEqual(_ object: Any?) -> Bool {

Original file line number	Diff line number	Diff line change
`@@ -29,7 +29,7 @@ internal class _NSKeyedArchiverUID : NSObject {`
`29`	`29`	`}`
`30`	`30`
`31`	`31`	`open override var hash: Int {`
`32`		`- return Int(bitPattern: CFHash(_cfObject as CFTypeRef!))`
	`32`	`+ return Int(bitPattern: CFHash(_cfObject as CFTypeRef?))`
`33`	`33`	`}`
`34`	`34`
`35`	`35`	`open override func isEqual(_ object: Any?) -> Bool {`