Add Equatable and Hashable conformance to GUID.

On Windows, `GUID` is a currency type and (along with its various typedefs) is used pervasively Windows offers `IsEqualGUID()` and `UuidHash()` for comparing and hashing them, respectively, but `IsEqualGUID()` is a macro in C mode and `UuidHash()` only provides a 16-bit hash. We should provide conformance to these protocols in the WinSDK overlay to provide equivalent functionality in Swift.

Author: grynspan

stdlib/public/Windows/WinSDK.swift

@@ -319,3 +319,24 @@ func _convertWindowsBoolToBool(_ b: WindowsBool) -> Bool {
  return b.boolValue
 }
 
+// GUID
+
+extension GUID: Equatable, Hashable {
+ @usableFromInline @_transparent
+ private var uint128Value: UInt128 {
+ unsafe withUnsafeBytes(of: self) { buffer in
+ // GUID is 32-bit-aligned only, so use loadUnaligned().
+ unsafe buffer.baseAddress!.loadUnaligned(as: UInt128.self)
+ }
+ }
+
+ @_transparent
+ public static func ==(lhs: Self, rhs: Self) -> Bool {
+ lhs.uint128Value == rhs.uint128Value
+ }
+
+ @_transparent
+ public func hash(into: inout Hasher) {
+ hasher.combine(uint128Value)
+ }
+}