Update for SE-0128

Author: trentxintong

Foundation/CharacterSet.swift

@@ -122,7 +122,7 @@ public struct CharacterSet : ReferenceConvertible, Equatable, Hashable, SetAlgeb
     ///
     /// It is the caller's responsibility to ensure that the values represent valid `UnicodeScalar` values, if that is what is desired.
     public init(charactersIn range: ClosedRange<UnicodeScalar>) {
-        let halfOpenRange = range.lowerBound..<UnicodeScalar(range.upperBound.value + 1)
+        let halfOpenRange = range.lowerBound..<UnicodeScalar(range.upperBound.value + 1)!
         _wrapped = _SwiftNSCharacterSet(immutableObject: NSCharacterSet(range: _utfRangeToNSRange(halfOpenRange)))
     }
 
@@ -313,7 +313,7 @@ public struct CharacterSet : ReferenceConvertible, Equatable, Hashable, SetAlgeb
     ///
     /// It is the caller's responsibility to ensure that the values represent valid `UnicodeScalar` values, if that is what is desired.
     public mutating func insert(charactersIn range: ClosedRange<UnicodeScalar>) {
-        let halfOpenRange = range.lowerBound..<UnicodeScalar(range.upperBound.value + 1)
+        let halfOpenRange = range.lowerBound..<UnicodeScalar(range.upperBound.value + 1)!
         let nsRange = _utfRangeToNSRange(halfOpenRange)
         _applyUnmanagedMutation {
             $0.addCharacters(in: nsRange)
@@ -330,7 +330,7 @@ public struct CharacterSet : ReferenceConvertible, Equatable, Hashable, SetAlgeb
 
     /// Remove a closed range of integer values from the `CharacterSet`.
     public mutating func remove(charactersIn range: ClosedRange<UnicodeScalar>) {
-        let halfOpenRange = range.lowerBound..<UnicodeScalar(range.upperBound.value + 1)
+        let halfOpenRange = range.lowerBound..<UnicodeScalar(range.upperBound.value + 1)!
         let nsRange = _utfRangeToNSRange(halfOpenRange)
         _applyUnmanagedMutation {
             $0.removeCharacters(in: nsRange)
@@ -488,6 +488,6 @@ extension CharacterSet {
 
 extension CharacterSet {
     public func contains(_ member: unichar) -> Bool {
-        return contains(UnicodeScalar(member))
+        return contains(UnicodeScalar(member)!)
     }
 }

Foundation/NSURLResponse.swift

@@ -357,9 +357,9 @@ private extension String {
             }
         }
 
-        let escape = UnicodeScalar(0x5c)    //  \
-        let quote = UnicodeScalar(0x22)     //  "
-        let separator = UnicodeScalar(0x3b) //  ;
+        let escape = UnicodeScalar(0x5c)!    //  \
+        let quote = UnicodeScalar(0x22)!     //  "
+        let separator = UnicodeScalar(0x3b)! //  ;
         enum State {
             case nonQuoted(String)
             case nonQuotedEscaped(String)