Make Hashable: ~Copyable

Author: airspeedswift

stdlib/public/core/Hashable.swift

@@ -101,7 +101,7 @@
 ///         print("New tap detected at (\(nextTap.x), \(nextTap.y)).")
 ///     }
 ///     // Prints "New tap detected at (0, 1).")
-public protocol Hashable: Equatable {
+public protocol Hashable: Equatable & ~Copyable {
   /// The hash value.
   ///
   /// Hash values are not guaranteed to be equal across different executions of
@@ -135,9 +135,10 @@ public protocol Hashable: Equatable {
   func _rawHashValue(seed: Int) -> Int
 }
 
-extension Hashable {
+extension Hashable where Self: ~Copyable {
   @inlinable
   @inline(__always)
+  @_preInverseGenerics
   public func _rawHashValue(seed: Int) -> Int {
     var hasher = Hasher(_seed: seed)
     hasher.combine(self)
@@ -148,7 +149,8 @@ extension Hashable {
 // Called by synthesized `hashValue` implementations.
 @inlinable
 @inline(__always)
-public func _hashValue<H: Hashable>(for value: H) -> Int {
+@_preInverseGenerics
+public func _hashValue<H: Hashable & ~Copyable>(for value: borrowing H) -> Int {
   return value._rawHashValue(seed: 0)
 }
 

stdlib/public/core/Hasher.swift

@@ -350,7 +350,8 @@ public struct Hasher {
   /// - Parameter value: A value to add to the hasher.
   @inlinable
   @inline(__always)
-  public mutating func combine<H: Hashable>(_ value: H) {
+  @_preInverseGenerics
+  public mutating func combine<H: Hashable & ~Copyable>(_ value: borrowing H) {
     value.hash(into: &self)
   }
 

stdlib/public/core/Optional.swift

@@ -586,13 +586,15 @@ extension Optional: Equatable where Wrapped: Equatable & ~Copyable {
   }
 }
 
-extension Optional: Hashable where Wrapped: Hashable {
+@_preInverseGenerics
+extension Optional: Hashable where Wrapped: Hashable & ~Copyable {
   /// Hashes the essential components of this value by feeding them into the
   /// given hasher.
   ///
   /// - Parameter hasher: The hasher to use when combining the components
   ///   of this instance.
   @inlinable
+  @_preInverseGenerics
   public func hash(into hasher: inout Hasher) {
     switch self {
     case .none: