Merge pull request #3944 from DougGregor/rdar-27658748

Author: swift-ci

lib/SIL/SILType.cpp

@@ -465,8 +465,8 @@ static bool isBridgedErrorClass(SILModule &M,
     t = archetypeType->getSuperclass();
 
   // NSError (TODO: and CFError) can be bridged.
-  auto errorType = M.Types.getNSErrorType();
-  if (t && errorType && t->isEqual(errorType)) {
+  auto nsErrorType = M.Types.getNSErrorType();
+  if (t && nsErrorType && nsErrorType->isExactSuperclassOf(t, nullptr)) {
     return true;
   }
 

test/1_stdlib/ErrorBridged.swift

@@ -582,4 +582,12 @@ ErrorBridgingTests.test("Customizing localization/recovery laziness") {
   }
 }
 
+class MyNSError : NSError {  }
+
+ErrorBridgingTests.test("NSError subclass identity") {
+  let myNSError: Error = MyNSError(domain: "MyNSError", code: 0, userInfo: [:])
+  let nsError = myNSError as NSError
+  expectTrue(type(of: nsError) == MyNSError.self)
+}
+
 runAllTests()

test/SILGen/objc_error.swift

@@ -95,3 +95,16 @@ func testProduceOptionalError() -> Error? {
   // CHECK: function_ref @swift_convertNSErrorToError
   return produceOptionalError();
 }
+
+class MyNSError : NSError {
+  override init() {
+    super.init(domain: "MyNSError", code: 0, userInfo: [:])
+  }
+}
+
+// CHECK-LABEL: sil hidden @_TF10objc_error14eraseMyNSError
+// CHECK-NOT: return
+// CHECK: init_existential_ref
+func eraseMyNSError() -> Error {
+  return MyNSError()
+}