Merge pull request #2238 from jrose-apple/init-bitPattern-OpaquePointer

[stdlib] Add Int.init(bitPattern: OpaquePointer?)

This is effectively an amendment to SE-0016; see the pull request for more discussion.

Author: jrose-apple

stdlib/public/core/CTypes.swift

@@ -162,6 +162,20 @@ extension OpaquePointer : CustomDebugStringConvertible {
   }
 }
 
+extension Int {
+  @warn_unused_result
+  public init(bitPattern pointer: OpaquePointer?) {
+    self.init(bitPattern: UnsafePointer<Void>(pointer))
+  }
+}
+
+extension UInt {
+  @warn_unused_result
+  public init(bitPattern pointer: OpaquePointer?) {
+    self.init(bitPattern: UnsafePointer<Void>(pointer))
+  }
+}
+
 @warn_unused_result
 public func ==(lhs: OpaquePointer, rhs: OpaquePointer) -> Bool {
   return Bool(Builtin.cmp_eq_RawPointer(lhs._rawValue, rhs._rawValue))

stdlib/public/core/Runtime.swift.gyb

@@ -28,12 +28,11 @@ func _stdlib_atomicCompareExchangeStrongPtrImpl(
   expected: UnsafeMutablePointer<OpaquePointer?>,
   desired: OpaquePointer?) -> Bool {
 
-  // Bit-cast directly from 'OpaquePointer?' to 'Builtin.Word' because
-  // Builtin.RawPointer can't be nil.
+  // We use Builtin.Word here because Builtin.RawPointer can't be nil.
   let (oldValue, won) = Builtin.cmpxchg_seqcst_seqcst_Word(
     target._rawValue,
-    unsafeBitCast(expected.pointee, to: Builtin.Word.self),
-    unsafeBitCast(desired, to: Builtin.Word.self))
+    UInt(bitPattern: expected.pointee)._builtinWordValue,
+    UInt(bitPattern: desired)._builtinWordValue)
   expected.pointee = OpaquePointer(bitPattern: Int(oldValue))
   return Bool(won)
 }

test/1_stdlib/UnsafePointer.swift.gyb

@@ -151,7 +151,6 @@ ${SelfName}TestSuite.test("Hashable") {
   }
 }
 
-% if SelfName != 'OpaquePointer':
 ${SelfName}TestSuite.test("toInteger") {
   do {
     let word: Int = 0x12345678
@@ -172,7 +171,6 @@ ${SelfName}TestSuite.test("toInteger") {
     expectEqual(UInt(0), UInt(bitPattern: ptr))
   }
 }
-% end
 
 % end