From 101c7cbbdbe86a20043787609b11584abc4d46ce Mon Sep 17 00:00:00 2001
From: Mike Ash <mikeash@apple.com>
Date: Tue, 9 Oct 2018 12:48:44 -0400
Subject: [PATCH] [Runtime] Fix a leak when reading a weak property with
 Mirror.

SR-8878 rdar://problem/44872927
---
 stdlib/public/runtime/ReflectionMirror.mm |  1 +
 test/stdlib/WeakMirror.swift              | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/stdlib/public/runtime/ReflectionMirror.mm b/stdlib/public/runtime/ReflectionMirror.mm
index eae59f80fec5e..d4e248460fa2d 100644
--- a/stdlib/public/runtime/ReflectionMirror.mm
+++ b/stdlib/public/runtime/ReflectionMirror.mm
@@ -172,6 +172,7 @@ static bool loadSpecialReferenceStorage(OpaqueValue *fieldData,
                               reinterpret_cast<OpaqueValue *>(temporaryValue));
 
   type->deallocateBufferIn(&temporaryBuffer);
+  swift_unknownObjectRelease(strongValue);
   
   return true;
 }
diff --git a/test/stdlib/WeakMirror.swift b/test/stdlib/WeakMirror.swift
index e4e55264acdc7..eb6e8aead355e 100644
--- a/test/stdlib/WeakMirror.swift
+++ b/test/stdlib/WeakMirror.swift
@@ -99,6 +99,24 @@ mirrors.test("struct/StructHasNativeWeakReference") {
   print(extractedChild)
 }
 
+// SR-8878: Using Mirror to access a weak reference results in object
+// being retained indefinitely
+mirrors.test("class/NativeSwiftClassHasNativeWeakReferenceNoLeak") {
+  weak var verifier: AnyObject?
+  do {
+    let parent = NativeSwiftClassHasWeak(x: 1010)
+    let child = NativeSwiftClass(x: 2020)
+    verifier = child
+    parent.weakProperty = child
+    let mirror = Mirror(reflecting: parent)
+    let children = Array(mirror.children)
+    let extractedChild = children[0].1 as! NativeSwiftClass
+    expectNotNil(extractedChild)
+    expectNotNil(verifier)
+  }
+  expectNil(verifier)
+}
+
 #if _runtime(_ObjC)
 
 import Foundation