Mark all _unconditionallyBridgeFromObjectiveC functions as @_effects(readonly)

This enables removal of those bridging calls for dead parameters. Read-only lets the optimizer remove such a call if the result is not used.
Note that "readonly" means: no observable write operations. It's okay to allocate and initialize new objects.

rdar://problem/44944094

Author: eeckstein

stdlib/public/SDK/Dispatch/Data.swift

@@ -356,6 +356,7 @@ extension DispatchData {
 		return true
 	}
 
+	@_effects(readonly)
 	public static func _unconditionallyBridgeFromObjectiveC(_ source: __DispatchData?) -> DispatchData {
 		var result: DispatchData?
 		_forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/AffineTransform.swift

@@ -317,6 +317,7 @@ extension AffineTransform : _ObjectiveCBridgeable {
         return true // Can't fail
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ x: NSAffineTransform?) -> AffineTransform {
         guard let src = x else { return AffineTransform.identity }
         return AffineTransform(reference: src)

stdlib/public/SDK/Foundation/Calendar.swift

@@ -1113,6 +1113,7 @@ extension Calendar : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSCalendar?) -> Calendar {
         var result: Calendar?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/CharacterSet.swift

@@ -782,6 +782,7 @@ extension CharacterSet : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSCharacterSet?) -> CharacterSet {
         guard let src = source else { return CharacterSet() }
         return CharacterSet(_bridged: src)

stdlib/public/SDK/Foundation/Data.swift

@@ -1902,7 +1902,8 @@ extension Data : _ObjectiveCBridgeable {
         result = Data(referencing: input)
         return true
     }
-    
+
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSData?) -> Data {
         guard let src = source else { return Data() }
         return Data(referencing: src)

stdlib/public/SDK/Foundation/Date.swift

@@ -257,6 +257,7 @@ extension Date : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSDate?) -> Date {
         var result: Date?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/DateComponents.swift

@@ -338,6 +338,7 @@ extension DateComponents : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSDateComponents?) -> DateComponents {
         guard let src = source else { return DateComponents() }
         return DateComponents(reference: src)

stdlib/public/SDK/Foundation/DateInterval.swift

@@ -216,6 +216,7 @@ extension DateInterval : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSDateInterval?) -> DateInterval {
         var result: DateInterval?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/Decimal.swift

@@ -487,6 +487,7 @@ extension Decimal : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSDecimalNumber?) -> Decimal {
         guard let src = source else { return Decimal(_exponent: 0, _length: 0, _isNegative: 0, _isCompact: 0, _reserved: 0, _mantissa: (0, 0, 0, 0, 0, 0, 0, 0)) }
         return src.decimalValue

stdlib/public/SDK/Foundation/Foundation.swift

@@ -73,6 +73,7 @@ extension AnyHashable : _ObjectiveCBridgeable {
     return result != nil
   }
 
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(
     _ source: NSObject?
   ) -> AnyHashable {

stdlib/public/SDK/Foundation/IndexPath.swift

@@ -780,6 +780,7 @@ extension IndexPath : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSIndexPath?) -> IndexPath {
         guard let src = source else { return IndexPath() }
         return IndexPath(nsIndexPath: src)

stdlib/public/SDK/Foundation/IndexSet.swift

@@ -775,6 +775,7 @@ extension IndexSet : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSIndexSet?) -> IndexSet {
         guard let src = source else { return IndexSet() }
         return IndexSet(reference: src)

stdlib/public/SDK/Foundation/Locale.swift

@@ -466,6 +466,7 @@ extension Locale : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSLocale?) -> Locale {
         var result: Locale?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/Measurement.swift

@@ -238,6 +238,7 @@ extension Measurement : MeasurementBridgeType {
         }
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSMeasurement?) -> Measurement {
         let u = source!.unit as! UnitType
         return Measurement(value: source!.doubleValue, unit: u)

stdlib/public/SDK/Foundation/NSArray.swift

@@ -84,6 +84,7 @@ extension Array : _ObjectiveCBridgeable {
     return result != nil
   }
 
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(
     _ source: NSArray?
   ) -> Array {

stdlib/public/SDK/Foundation/NSDictionary.swift

@@ -125,6 +125,7 @@ extension Dictionary : _ObjectiveCBridgeable {
     return result != nil
   }
 
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(
     _ d: NSDictionary?
   ) -> Dictionary {

stdlib/public/SDK/Foundation/NSError.swift

@@ -547,6 +547,7 @@ extension _SwiftNewtypeWrapper where Self.RawValue == Error {
   }
 
   @inlinable // FIXME(sil-serialize-all)
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(
     _ source: NSError?
   ) -> Self {

stdlib/public/SDK/Foundation/NSNumber.swift

@@ -46,6 +46,7 @@ extension Int8 : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> Int8 {
         var result: Int8?
         guard let src = source else { return Int8(0) }
@@ -87,6 +88,7 @@ extension UInt8 : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> UInt8 {
         var result: UInt8?
         guard let src = source else { return UInt8(0) }
@@ -128,6 +130,7 @@ extension Int16 : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> Int16 {
         var result: Int16?
         guard let src = source else { return Int16(0) }
@@ -169,6 +172,7 @@ extension UInt16 : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> UInt16 {
         var result: UInt16?
         guard let src = source else { return UInt16(0) }
@@ -210,6 +214,7 @@ extension Int32 : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> Int32 {
         var result: Int32?
         guard let src = source else { return Int32(0) }
@@ -251,6 +256,7 @@ extension UInt32 : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> UInt32 {
         var result: UInt32?
         guard let src = source else { return UInt32(0) }
@@ -292,6 +298,7 @@ extension Int64 : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> Int64 {
         var result: Int64?
         guard let src = source else { return Int64(0) }
@@ -332,7 +339,8 @@ extension UInt64 : _ObjectiveCBridgeable {
         result = value
         return true
     }
-    
+
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> UInt64 {
         var result: UInt64?
         guard let src = source else { return UInt64(0) }
@@ -374,6 +382,7 @@ extension Int : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> Int {
         var result: Int?
         guard let src = source else { return Int(0) }
@@ -415,6 +424,7 @@ extension UInt : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> UInt {
         var result: UInt?
         guard let src = source else { return UInt(0) }
@@ -467,6 +477,7 @@ extension Float : _ObjectiveCBridgeable {
         return result != nil
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> Float {
         var result: Float?
         guard let src = source else { return Float(0) }
@@ -521,6 +532,7 @@ extension Double : _ObjectiveCBridgeable {
         return result != nil
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> Double {
         var result: Double?
         guard let src = source else { return Double(0) }
@@ -572,6 +584,7 @@ extension Bool : _ObjectiveCBridgeable {
         return false
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> Bool {
         var result: Bool?
         guard let src = source else { return false }
@@ -614,6 +627,7 @@ extension CGFloat : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNumber?) -> CGFloat {
         var result: CGFloat?
         guard let src = source else { return CGFloat(0) }

stdlib/public/SDK/Foundation/NSSet.swift

@@ -111,6 +111,7 @@ extension Set : _ObjectiveCBridgeable {
     return result != nil
   }
 
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(_ s: NSSet?) -> Set {
     // `nil` has historically been used as a stand-in for an empty
     // set; map it to an empty set.

stdlib/public/SDK/Foundation/Notification.swift

@@ -120,6 +120,7 @@ extension Notification : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSNotification?) -> Notification {
         guard let src = source else { return Notification(name: Notification.Name("")) }
         return Notification(name: src.name, object: src.object, userInfo: src.userInfo)

stdlib/public/SDK/Foundation/PersonNameComponents.swift

@@ -129,6 +129,7 @@ extension PersonNameComponents : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSPersonNameComponents?) -> PersonNameComponents {
         var result: PersonNameComponents?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/String.swift

@@ -50,6 +50,7 @@ extension String : _ObjectiveCBridgeable {
     return result != nil
   }
 
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(
     _ source: NSString?
   ) -> String {
@@ -82,6 +83,7 @@ extension Substring : _ObjectiveCBridgeable {
     return result != nil
   }
 
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(
     _ source: NSString?
   ) -> Substring {

stdlib/public/SDK/Foundation/TimeZone.swift

@@ -262,6 +262,7 @@ extension TimeZone : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSTimeZone?) -> TimeZone {
         var result: TimeZone?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/URL.swift

@@ -1205,6 +1205,7 @@ extension URL : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSURL?) -> URL {
         var result: URL?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/URLComponents.swift

@@ -372,6 +372,7 @@ extension URLComponents : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSURLComponents?) -> URLComponents {
         guard let src = source else { return URLComponents() }
         return URLComponents(reference: src)
@@ -465,6 +466,7 @@ extension URLQueryItem : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSURLQueryItem?) -> URLQueryItem {
         var result: URLQueryItem?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/URLRequest.swift

@@ -286,6 +286,7 @@ extension URLRequest : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSURLRequest?) -> URLRequest {
         var result: URLRequest?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Foundation/UUID.swift

@@ -148,6 +148,7 @@ extension UUID : _ObjectiveCBridgeable {
         return true
     }
 
+    @_effects(readonly)
     public static func _unconditionallyBridgeFromObjectiveC(_ source: NSUUID?) -> UUID {
         var result: UUID?
         _forceBridgeFromObjectiveC(source!, result: &result)

stdlib/public/SDK/Intents/INShortcut.swift

@@ -113,6 +113,7 @@ extension INShortcut : _ObjectiveCBridgeable {
     return true
   }
 
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(_ source: INShortcutReference?) -> INShortcut {
     guard let src = source else { fatalError("Missing source") }
     return INShortcut(from: src)

stdlib/public/core/BridgeObjectiveC.swift

@@ -78,6 +78,7 @@ public protocol _ObjectiveCBridgeable {
   /// implementation of `Swift.Array`'s conformance to
   /// `_ObjectiveCBridgeable` will produce an empty array rather than
   /// dynamically failing.
+  @_effects(readonly)
   static func _unconditionallyBridgeFromObjectiveC(_ source: _ObjectiveCType?)
       -> Self
 }
@@ -133,6 +134,7 @@ public struct _BridgeableMetatype: _ObjectiveCBridgeable {
   }
 
   @inlinable // FIXME(sil-serialize-all)
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(_ source: AnyObject?)
       -> _BridgeableMetatype {
     var result: _BridgeableMetatype?

stdlib/public/core/NewtypeWrapper.swift

@@ -133,6 +133,7 @@ extension _SwiftNewtypeWrapper where Self.RawValue : _ObjectiveCBridgeable {
   }
 
   @inlinable // FIXME(sil-serialize-all)
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(
     _ source: Self.RawValue._ObjectiveCType?
   ) -> Self {
@@ -165,6 +166,7 @@ extension _SwiftNewtypeWrapper where Self.RawValue: AnyObject {
   }
 
   @inlinable // FIXME(sil-serialize-all)
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(
     _ source: Self.RawValue?
   ) -> Self {

stdlib/public/core/Optional.swift

@@ -727,6 +727,7 @@ extension Optional : _ObjectiveCBridgeable {
   }
 
   @inlinable // FIXME(sil-serialize-all)
+  @_effects(readonly)
   public static func _unconditionallyBridgeFromObjectiveC(_ source: AnyObject?)
       -> Optional<Wrapped> {
     if let nonnullSource = source {