Work around importer availability bug

Author: parkera

stdlib/public/SDK/Foundation/Calendar.swift

@@ -21,6 +21,9 @@ internal func __NSCalendarAutoupdating() -> NSCalendar
 @_silgen_name("__NSCalendarCurrent")
 internal func __NSCalendarCurrent() -> NSCalendar
 
+@_silgen_name("__NSCalendarInit")
+internal func __NSCalendarInit(_ identifier : NSString) -> NSCalendar?
+
 /**
  `Calendar` encapsulates information about systems of reckoning time in which the beginning, length, and divisions of a year are defined. It provides information about the calendar and support for calendrical computations such as determining the range of a given calendrical unit and adding units to a given absolute time.
 */
@@ -104,7 +107,8 @@ public struct Calendar : CustomStringConvertible, CustomDebugStringConvertible,
     ///
     /// - parameter identifier: The kind of calendar to use.
     public init(identifier: Identifier) {
-        _handle = _MutableHandle(adoptingReference: NSCalendar(identifier: Calendar._toNSCalendarIdentifier(identifier))!)
+        let result = __NSCalendarInit(Calendar._toNSCalendarIdentifier(identifier))!
+        _handle = _MutableHandle(adoptingReference: result)
         _autoupdating = false
     }
 

stdlib/public/SDK/Foundation/Thunks.mm

@@ -122,6 +122,14 @@
 
 // A way to get various Calendar, Locale, and TimeZone singletons without bridging twice
 
+// Unfortunately the importer does not realize that [NSCalendar initWithIdentifier:] has been around forever, and only sees the iOS 8 availability of [NSCalendar calendarWithIdentifier:].
+SWIFT_CC(swift)
+extern "C" NS_RETURNS_RETAINED NSCalendar * __nullable __NSCalendarInit(NSString * NS_RELEASES_ARGUMENT __nonnull identifier) {
+    NSCalendar *result = [[NSCalendar alloc] initWithCalendarIdentifier:identifier];
+    [identifier release];
+    return result;
+}
+
 SWIFT_CC(swift)
 extern "C" NS_RETURNS_RETAINED NSCalendar *__NSCalendarAutoupdating() {
     return [[NSCalendar autoupdatingCurrentCalendar] retain];