---

yaml
---
r: 347799
b: refs/heads/master
c: f41aac9
h: refs/heads/master
i:
  347797: 502852f
  347795: f5ee60d
  347791: 2a26047

Author: swift-ci

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: 120ca85a3a08d52ab26df817024e7db5b80a9a68
+refs/heads/master: f41aac9a3d81369316c08067d547e27eee01f116
 refs/heads/master-next: 203b3026584ecad859eb328b2e12490099409cd5
 refs/tags/osx-passed: b6b74147ef8a386f532cf9357a1bde006e552c54
 refs/tags/swift-2.2-SNAPSHOT-2015-12-01-a: 6bb18e013c2284f2b45f5f84f2df2887dc0f7dea

trunk/stdlib/public/runtime/SwiftObject.mm

@@ -195,11 +195,15 @@ Class _swift_classOfObjCHeapObject(OpaqueValue *value) {
 
 @implementation SwiftObject
 + (void)initialize {
-#if SWIFT_HAS_ISA_MASKING
-  // Really old ObjC runtimes don't have this symbol, which is OK. If
-  // the symbol exists, then our value must match.
-  assert(&objc_debug_isa_class_mask == NULL ||
-         objc_debug_isa_class_mask == SWIFT_ISA_MASK);
+#if SWIFT_HAS_ISA_MASKING && !NDEBUG
+  // Older OSes may not have this variable, or it may not match. This code only
+  // runs on older OSes in certain testing scenarios, so that doesn't matter.
+  // Only perform the check on newer OSes where the value should definitely
+  // match.
+  if (!_swift_isBackDeploying()) {
+    assert(&objc_debug_isa_class_mask);
+    assert(objc_debug_isa_class_mask == SWIFT_ISA_MASK);
+  }
 #endif
 }