[stdlib] Deprecated PlaygroundQuickLook and CustomPlaygroundQuickLookable.

Deprecated the `PlaygroundQuickLook` enum and `CustomPlaygroundQuickLookable`
protocol. These are being targeted for removal in Swift 5, so we want to
unconditionally deprecate them now to encourage use of
`CustomPlaygroundDisplayConvertible` instead.

This commit includes deprecated the various `CustomPlaygroundQuickLookable`
conformances across the standard library and overlay libraries.

Author: cwakamo

stdlib/public/SDK/AppKit/AppKit.swift

@@ -14,6 +14,7 @@ import Foundation
 @_exported import AppKit
 
 extension NSCursor : _DefaultCustomPlaygroundQuickLookable {
+  @available(*, deprecated, message: "NSCursor._defaultCustomPlaygroundQuickLook will be removed in a future Swift version")
   public var _defaultCustomPlaygroundQuickLook: PlaygroundQuickLook {
     return .image(image)
   }
@@ -24,6 +25,7 @@ internal struct _NSViewQuickLookState {
 }
 
 extension NSView : _DefaultCustomPlaygroundQuickLookable {
+  @available(*, deprecated, message: "NSView._defaultCustomPlaygroundQuickLook will be removed in a future Swift version")
   public var _defaultCustomPlaygroundQuickLook: PlaygroundQuickLook {
     // if you set NSView.needsDisplay, you can get yourself in a recursive scenario where the same view
     // could need to draw itself in order to get a QLObject for itself, which in turn if your code was

stdlib/public/SDK/CoreGraphics/CoreGraphics.swift

@@ -232,6 +232,7 @@ extension CGPoint : CustomReflectable, CustomPlaygroundQuickLookable {
     return Mirror(self, children: ["x": x, "y": y], displayStyle: .`struct`)
   }
 
+  @available(*, deprecated, message: "CGPoint.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .point(Double(x), Double(y))
   }
@@ -299,6 +300,7 @@ extension CGSize : CustomReflectable, CustomPlaygroundQuickLookable {
       displayStyle: .`struct`)
   }
 
+  @available(*, deprecated, message: "CGSize.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .size(Double(width), Double(height))
   }
@@ -436,6 +438,7 @@ extension CGRect : CustomReflectable, CustomPlaygroundQuickLookable {
       displayStyle: .`struct`)
   }
 
+  @available(*, deprecated, message: "CGRect.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .rectangle(
       Double(origin.x), Double(origin.y),

stdlib/public/SDK/Foundation/Date.swift

@@ -280,6 +280,7 @@ extension Date : CustomPlaygroundQuickLookable {
         return df.string(from: self)
     }
 
+    @available(*, deprecated, message: "Date.customPlaygroundQuickLook will be removed in a future Swift version")
     public var customPlaygroundQuickLook: PlaygroundQuickLook {
         return .text(summary)
     }

stdlib/public/SDK/Foundation/NSDate.swift

@@ -21,6 +21,7 @@ extension NSDate : CustomPlaygroundQuickLookable {
     return df.string(from: self as Date)
   }
 
+  @available(*, deprecated, message: "NSDate.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .text(summary)
   }

stdlib/public/SDK/Foundation/NSRange.swift

@@ -198,6 +198,7 @@ extension NSRange : CustomReflectable {
 }
 
 extension NSRange : CustomPlaygroundQuickLookable {
+    @available(*, deprecated, message: "NSRange.customPlaygroundQuickLook will be removed in a future Swift version")
     public var customPlaygroundQuickLook: PlaygroundQuickLook {
         return .range(Int64(location), Int64(length))
     }

stdlib/public/SDK/Foundation/NSString.swift

@@ -113,6 +113,7 @@ extension NSString {
 }
 
 extension NSString : CustomPlaygroundQuickLookable {
+  @available(*, deprecated, message: "NSString.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .text(self as String)
   }

stdlib/public/SDK/Foundation/NSURL.swift

@@ -13,6 +13,7 @@
 @_exported import Foundation // Clang module
 
 extension NSURL : CustomPlaygroundQuickLookable {
+  @available(*, deprecated, message: "NSURL.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     guard let str = absoluteString else { return .text("Unknown URL") }
     return .url(str)

stdlib/public/SDK/Foundation/URL.swift

@@ -1202,6 +1202,7 @@ extension NSURL : _HasCustomAnyHashableRepresentation {
 }
 
 extension URL : CustomPlaygroundQuickLookable {
+    @available(*, deprecated, message: "URL.customPlaygroundQuickLook will be removed in a future Swift version")
     public var customPlaygroundQuickLook: PlaygroundQuickLook {
         return .url(absoluteString)
     }

stdlib/public/SDK/SpriteKit/SpriteKitQuickLooks.swift.gyb

@@ -15,6 +15,7 @@
 % for Self in ['SKShapeNode', 'SKSpriteNode', 'SKTextureAtlas', 'SKTexture']:
 
 extension ${Self} : CustomPlaygroundQuickLookable {
+  @available(*, deprecated, message: "${Self}.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     let data = (self as AnyObject)._copyImageData?() as Data?
 

stdlib/public/SDK/UIKit/UIKit.swift

@@ -231,6 +231,7 @@ internal struct _UIViewQuickLookState {
 }
 
 extension UIView : _DefaultCustomPlaygroundQuickLookable {
+  @available(*, deprecated, message: "UIView._defaultCustomPlaygroundQuickLook will be removed in a future Swift version")
   public var _defaultCustomPlaygroundQuickLook: PlaygroundQuickLook {
     if _UIViewQuickLookState.views.contains(self) {
       return .view(UIImage())

stdlib/public/core/Mirror.swift

@@ -662,6 +662,7 @@ internal extension Mirror {
 
 /// The sum of types that can be used as a Quick Look representation.
 @_fixed_layout // FIXME(sil-serialize-all)
+@available(*, deprecated, message: "PlaygroundQuickLook will be removed in a future Swift version. For customizing how types are presented in playgrounds, use CustomPlaygroundDisplayConvertible instead.")
 public enum PlaygroundQuickLook {
   /// Plain text.
   case text(String)
@@ -748,6 +749,7 @@ extension PlaygroundQuickLook {
   /// - Parameter subject: The instance to represent with the resulting Quick
   ///   Look.
   @_inlineable // FIXME(sil-serialize-all)
+  @available(*, deprecated, message: "PlaygroundQuickLook will be removed in a future Swift version.")
   public init(reflecting subject: Any) {
     if let customized = subject as? CustomPlaygroundQuickLookable {
       self = customized.customPlaygroundQuickLook
@@ -773,6 +775,7 @@ extension PlaygroundQuickLook {
 /// with the representation supplied for your type by default, you can make it
 /// conform to the `CustomPlaygroundQuickLookable` protocol and provide a
 /// custom `PlaygroundQuickLook` instance.
+@available(*, deprecated, message: "CustomPlaygroundQuickLookable will be removed in a future Swift version. For customizing how types are presented in playgrounds, use CustomPlaygroundDisplayConvertible instead.")
 public protocol CustomPlaygroundQuickLookable {
   /// A custom playground Quick Look for this instance.
   ///
@@ -784,6 +787,7 @@ public protocol CustomPlaygroundQuickLookable {
 
 // A workaround for <rdar://problem/26182650>
 // FIXME(ABI)#50 (Dynamic Dispatch for Class Extensions) though not if it moves out of stdlib.
+@available(*, deprecated, message: "_DefaultCustomPlaygroundQuickLookable will be removed in a future Swift version. For customizing how types are presented in playgrounds, use CustomPlaygroundDisplayConvertible instead.")
 public protocol _DefaultCustomPlaygroundQuickLookable {
   var _defaultCustomPlaygroundQuickLook: PlaygroundQuickLook { get }
 }

stdlib/public/core/Mirrors.swift.gyb

@@ -48,6 +48,7 @@ extension ${Type[0]} : CustomReflectable {
 extension ${Type[0]} : CustomPlaygroundQuickLookable {
   /// A custom playground Quick Look for the `${Type[0]}` instance.
   @_inlineable // FIXME(sil-serialize-all)
+  @available(*, deprecated, message: "${Type[0]}.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return ${Type[1]}(${Type[2]})
   }

stdlib/public/core/StringUTF16.swift

@@ -447,6 +447,7 @@ extension String.UTF16View : CustomReflectable {
 
 extension String.UTF16View : CustomPlaygroundQuickLookable {
   @_inlineable // FIXME(sil-serialize-all)
+  @available(*, deprecated, message: "UTF16View.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .text(description)
   }

stdlib/public/core/StringUTF8.swift

@@ -634,6 +634,7 @@ extension String.UTF8View : CustomReflectable {
 
 extension String.UTF8View : CustomPlaygroundQuickLookable {
   @_inlineable // FIXME(sil-serialize-all)
+  @available(*, deprecated, message: "UTF8View.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .text(description)
   }

stdlib/public/core/StringUnicodeScalarView.swift

@@ -544,6 +544,7 @@ extension String.UnicodeScalarView : CustomReflectable {
 
 extension String.UnicodeScalarView : CustomPlaygroundQuickLookable {
   @_inlineable // FIXME(sil-serialize-all)
+  @available(*, deprecated, message: "UnicodeScalarView.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .text(description)
   }

stdlib/public/core/Substring.swift.gyb

@@ -338,6 +338,7 @@ extension Substring : CustomReflectable {
 
 extension Substring : CustomPlaygroundQuickLookable {
   @_inlineable // FIXME(sil-serialize-all)
+  @available(*, deprecated, message: "Substring.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return String(self).customPlaygroundQuickLook
   }

stdlib/public/core/UnsafePointer.swift.gyb

@@ -1004,6 +1004,7 @@ extension ${Self} : CustomPlaygroundQuickLookable {
   }
 
   @_inlineable // FIXME(sil-serialize-all)
+  @available(*, deprecated, message: "${Self}.customPlaygroundQuickLook will be removed in a future Swift version")
   public var customPlaygroundQuickLook: PlaygroundQuickLook {
     return .text(summary)
   }

stdlib/public/core/UnsafeRawPointer.swift.gyb

@@ -996,6 +996,7 @@ extension Unsafe${Mutable}RawPointer : CustomReflectable {
 extension Unsafe${Mutable}RawPointer : CustomPlaygroundQuickLookable {
   @_inlineable // FIXME(sil-serialize-all)
   @_versioned // FIXME(sil-serialize-all)
+  @available(*, deprecated, message: "Unsafe${Mutable}RawPointer.customPlaygroundQuickLook will be removed in a future Swift version")
   internal var summary: String {
     let selfType = "${Self}"
     let ptrValue = UInt64(