[stdlib] Removing the StringProtocol.init<T: StringProtocol>

Author: Max Moiseev

stdlib/public/core/String.swift

@@ -21,11 +21,6 @@ public protocol StringProtocol
   Hashable
   where Iterator.Element == Character {
 
-  // this should be just <T : StringProtocol>
-  init<
-    T : LosslessStringConvertible & Sequence
-  >(_ other: T) where T.Iterator.Element == Character
-
   associatedtype UTF8Index
   var utf8: String.UTF8View { get }
   associatedtype UTF16Index
@@ -83,14 +78,6 @@ public protocol StringProtocol
   ) rethrows -> Result
 }
 
-extension StringProtocol {
-  public init<
-    T : LosslessStringConvertible & Sequence
-  >(_ other: T) where T.Iterator.Element == Character {
-    self.init(other.description.characters)
-  }
-}
-
 /// Call body with a pointer to zero-terminated sequence of
 /// `TargetEncoding.CodeUnit` representing the same string as `source`, when
 /// `source` is interpreted as being encoded with `SourceEncoding`.

stdlib/public/core/StringRangeReplaceableCollection.swift.gyb

@@ -41,11 +41,8 @@ extension String : StringProtocol {
   // - init<S>(_ characters: S) where S : Sequence, S.Iterator.Element == Character
   // Cannot simply do init(_: String) as that would itself be ambiguous with
   // init?(_ description: String)
-  public init<
-    T : LosslessStringConvertible & Sequence
-  >(_ other: T)
-  where T.Iterator.Element == Character {
-    self = other.description
+  public init<T : StringProtocol>(_ other: T) {
+    self.init(other.characters)
   }
 
   /// The position of the first character in a nonempty string.