JSONEncoder overlay changes (#1561) (#1661)

Author: ianpartridge

Foundation/Codable.swift

@@ -1,11 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
 // This source file is part of the Swift.org open source project
 //
 // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
-// See http://swift.org/LICENSE.txt for license information
-// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Errors
+//===----------------------------------------------------------------------===//
+
+// Both of these error types bridge to NSError, and through the entry points they use, no further work is needed to make them localized.
+extension EncodingError : LocalizedError {}
+extension DecodingError : LocalizedError {}
 
 //===----------------------------------------------------------------------===//
 // Error Utilities
@@ -39,11 +50,9 @@ internal extension DecodingError {
             return "an array"
         } else if value is [String : Any] {
             return "a dictionary"
-        } else if value is Bool {
-            return "a boolean"
         } else {
-            // This should never happen -- we somehow have a non-JSON type here.
-            preconditionFailure("Invalid storage type \(type(of: value)).")
+            return "\(type(of: value))"
         }
     }
 }
+