[stdlib] Streamable => TextOutputStreamable

This is logically part of
[SE-0086](https://github.com/apple/swift-evolution/blob/master/proposals/0086-drop-foundation-ns.md)
since it goes with 2a4e916 (Rename OutputStream to TextOutputStream [SE-0086])

Author: Dave Abrahams

stdlib/public/core/Mirror.swift

@@ -838,7 +838,7 @@ extension String {
   /// string representation of `instance` in one of the following ways,
   /// depending on its protocol conformance:
   ///
-  /// - If `instance` conforms to the `Streamable` protocol, the result is
+  /// - If `instance` conforms to the `TextOutputStreamable` protocol, the result is
   ///   obtained by calling `instance.write(to: s)` on an empty string `s`.
   /// - If `instance` conforms to the `CustomStringConvertible` protocol, the
   ///   result is `instance.description`.
@@ -888,7 +888,7 @@ extension String {
   ///   the result is `subject.debugDescription`.
   /// - If `subject` conforms to the `CustomStringConvertible` protocol, the
   ///   result is `subject.description`.
-  /// - If `subject` conforms to the `Streamable` protocol, the result is
+  /// - If `subject` conforms to the `TextOutputStreamable` protocol, the result is
   ///   obtained by calling `subject.write(to: s)` on an empty string `s`.
   /// - An unspecified result is supplied automatically by the Swift standard
   ///   library.

stdlib/public/core/OutputStream.swift

@@ -81,23 +81,26 @@ extension TextOutputStream {
 
 /// A source of text-streaming operations.
 ///
-/// Instances of types that conform to the `Streamable` protocol can write
-/// their value to instances of any type that conforms to the `TextOutputStream`
-/// protocol. The Swift standard library's text-related types, `String`,
-/// `Character`, and `UnicodeScalar`, all conform to `Streamable`.
+/// Instances of types that conform to the `TextOutputStreamable` protocol can
+/// write their value to instances of any type that conforms to the
+/// `TextOutputStream` protocol. The Swift standard library's text-related
+/// types, `String`, `Character`, and `UnicodeScalar`, all conform to
+/// `TextOutputStreamable`.
 ///
-/// Conforming to the Streamable Protocol
+/// Conforming to the TextOutputStreamable Protocol
 /// =====================================
 ///
-/// To add `Streamable` conformance to a custom type, implement the required
-/// `write(to:)` method. Call the given output stream's `write(_:)` method in
-/// your implementation.
-public protocol Streamable {
+/// To add `TextOutputStreamable` conformance to a custom type, implement the
+/// required `write(to:)` method. Call the given output stream's `write(_:)`
+/// method in your implementation.
+public protocol TextOutputStreamable {
   /// Writes a textual representation of this instance into the given output
   /// stream.
   func write<Target : TextOutputStream>(to target: inout Target)
 }
-typealias TextOutputStreamable = Streamable
+
+@available(*, unavailable, renamed: "TextOutputStreamable")
+typealias Streamable = TextOutputStreamable
 
 /// A type with a customized textual representation.
 ///
@@ -347,7 +350,7 @@ internal func _print_unlocked<T, TargetStream : TextOutputStream>(
     debugPrintable.debugDescription.write(to: &target)
     return
   }
-  if case let streamableObject as Streamable = value {
+  if case let streamableObject as TextOutputStreamable = value {
     streamableObject.write(to: &target)
     return
   }
@@ -374,7 +377,7 @@ internal func _print_unlocked<T, TargetStream : TextOutputStream>(
 /// This function is forbidden from being inlined because when building the
 /// standard library inlining makes us drop the special semantics.
 @inline(never) @effects(readonly)
-func _toStringReadOnlyStreamable<T : Streamable>(_ x: T) -> String {
+func _toStringReadOnlyStreamable<T : TextOutputStreamable>(_ x: T) -> String {
   var result = ""
   x.write(to: &result)
   return result
@@ -403,7 +406,7 @@ public func _debugPrint_unlocked<T, TargetStream : TextOutputStream>(
     return
   }
 
-  if let streamableObject = value as? Streamable {
+  if let streamableObject = value as? TextOutputStreamable {
     streamableObject.write(to: &target)
     return
   }
@@ -416,7 +419,8 @@ internal func _dumpPrint_unlocked<T, TargetStream : TextOutputStream>(
     _ value: T, _ mirror: Mirror, _ target: inout TargetStream
 ) {
   if let displayStyle = mirror.displayStyle {
-    // Containers and tuples are always displayed in terms of their element count
+    // Containers and tuples are always displayed in terms of their element
+    // count
     switch displayStyle {
     case .tuple:
       let count = mirror.children.count
@@ -449,7 +453,7 @@ internal func _dumpPrint_unlocked<T, TargetStream : TextOutputStream>(
     return
   }
 
-  if let streamableObject = value as? Streamable {
+  if let streamableObject = value as? TextOutputStreamable {
     streamableObject.write(to: &target)
     return
   }
@@ -520,7 +524,7 @@ extension String : TextOutputStream {
 // Streamables
 //===----------------------------------------------------------------------===//
 
-extension String : Streamable {
+extension String : TextOutputStreamable {
   /// Writes the string into the given output stream.
   /// 
   /// - Parameter target: An output stream.
@@ -529,7 +533,7 @@ extension String : Streamable {
   }
 }
 
-extension Character : Streamable {
+extension Character : TextOutputStreamable {
   /// Writes the character into the given output stream.
   ///
   /// - Parameter target: An output stream.
@@ -538,7 +542,7 @@ extension Character : Streamable {
   }
 }
 
-extension UnicodeScalar : Streamable {
+extension UnicodeScalar : TextOutputStreamable {
   /// Writes the textual representation of the Unicode scalar into the given
   /// output stream.
   ///
@@ -569,7 +573,7 @@ internal struct _TeeStream<
 @available(*, unavailable, renamed: "TextOutputStream")
 public typealias OutputStreamType = TextOutputStream
 
-extension Streamable {
+extension TextOutputStreamable {
   @available(*, unavailable, renamed: "write(to:)")
   public func writeTo<Target : TextOutputStream>(_ target: inout Target) {
     Builtin.unreachable()

stdlib/public/core/Print.swift

@@ -50,7 +50,7 @@
 ///   - terminator: The string to print after all items have been printed. The
 ///     default is a newline (`"\n"`).
 ///
-/// - SeeAlso: `debugPrint(_:separator:terminator:)`, `Streamable`,
+/// - SeeAlso: `debugPrint(_:separator:terminator:)`, `TextOutputStreamable`,
 ///   `CustomStringConvertible`, `CustomDebugStringConvertible`
 @inline(never)
 @_semantics("stdlib_binary_only")
@@ -113,7 +113,7 @@ public func print(
 ///   - terminator: The string to print after all items have been printed. The
 ///     default is a newline (`"\n"`).
 ///
-/// - SeeAlso: `print(_:separator:terminator:)`, `Streamable`,
+/// - SeeAlso: `print(_:separator:terminator:)`, `TextOutputStreamable`,
 ///   `CustomStringConvertible`, `CustomDebugStringConvertible`
 @inline(never)
 @_semantics("stdlib_binary_only")
@@ -174,7 +174,7 @@ public func debugPrint(
 ///
 /// - SeeAlso: `print(_:separator:terminator:)`,
 ///   `debugPrint(_:separator:terminator:to:)`, `TextOutputStream`,
-///   `Streamable`, `CustomStringConvertible`, `CustomDebugStringConvertible`
+///   `TextOutputStreamable`, `CustomStringConvertible`, `CustomDebugStringConvertible`
 @inline(__always)
 public func print<Target : TextOutputStream>(
   _ items: Any...,
@@ -225,7 +225,7 @@ public func print<Target : TextOutputStream>(
 ///     item.
 ///
 /// - SeeAlso: `debugPrint(_:separator:terminator:)`,
-///   `print(_:separator:terminator:to:)`, `TextOutputStream`, `Streamable`,
+///   `print(_:separator:terminator:to:)`, `TextOutputStream`, `TextOutputStreamable`,
 ///   `CustomStringConvertible`, `CustomDebugStringConvertible`
 @inline(__always)
 public func debugPrint<Target : TextOutputStream>(

test/1_stdlib/Optional.swift

@@ -351,7 +351,7 @@ class TestString : CustomStringConvertible, CustomDebugStringConvertible {
     return "XString"
   }
 }
-class TestStream : Streamable {
+class TestStream : TextOutputStreamable {
   func write<Target : TextOutputStream>(to target: inout Target) {
     target.write("AStream")
   }
@@ -371,8 +371,8 @@ OptionalTests.test("Optional TextOutputStream") {
   let optNoString: TestNoString? = TestNoString()
   expectFalse(optNoString is CustomStringConvertible)
   expectFalse(canGenericCast(optNoString, CustomStringConvertible.self))
-  expectFalse(optNoString is Streamable)
-  expectFalse(canGenericCast(optNoString, Streamable.self))
+  expectFalse(optNoString is TextOutputStreamable)
+  expectFalse(canGenericCast(optNoString, TextOutputStreamable.self))
   expectTrue(optNoString is CustomDebugStringConvertible)
   expectTrue(canGenericCast(optNoString, CustomDebugStringConvertible.self))
   expectEqual(String(describing: optNoString), "Optional(main.TestNoString)")
@@ -388,8 +388,8 @@ OptionalTests.test("Optional TextOutputStream") {
   expectEqual(debugPrintStr(optString), "Optional(XString)")
 
   let optStream: TestStream? = TestStream()
-  expectTrue(optStream is Streamable)
-  expectTrue(canGenericCast(optStream, Streamable.self))
+  expectTrue(optStream is TextOutputStreamable)
+  expectTrue(canGenericCast(optStream, TextOutputStreamable.self))
   expectTrue(optStream is CustomDebugStringConvertible)
   expectTrue(canGenericCast(optStream, CustomDebugStringConvertible.self))
   expectEqual(String(describing: TestStream()), "AStream")

test/1_stdlib/Renames.swift

@@ -355,7 +355,7 @@ func _Optional<T>(x: T) {
 func _TextOutputStream() {
   func fn<S : OutputStreamType>(_: S) {} // expected-error {{'OutputStreamType' has been renamed to 'TextOutputStream'}} {{15-31=TextOutputStream}} {{none}}
 }
-func _TextOutputStream<S : Streamable, O : TextOutputStream>(s: S, o: O) {
+func _TextOutputStream<S : TextOutputStreamable, O : TextOutputStream>(s: S, o: O) {
   var o = o
   s.writeTo(&o) // expected-error {{'writeTo' has been renamed to 'write(to:)'}} {{5-12=write}} {{13-13=to: }} {{none}}
 }