commit 015b7383c9dd29dec6d572dfe71547603b379368
Author: Grant Paul <git@grantpaul.com>
Date:   Wed Jul 30 23:02:11 2014 -0700

    Implicitly convert C++ wrappers to ObjC objects in @synchronized.

diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 1ddb369..c1607f9 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -3119,9 +3119,24 @@ Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) {
   if (!type->isDependentType() &&
       !type->isObjCObjectPointerType()) {
     const PointerType *pointerType = type->getAs<PointerType>();
-    if (!pointerType || !pointerType->getPointeeType()->isVoidType())
-      return Diag(atLoc, diag::error_objc_synchronized_expects_object)
-               << type << operand->getSourceRange();
+    if (!pointerType || !pointerType->getPointeeType()->isVoidType()) {
+      if (getLangOpts().CPlusPlus) {
+        if (RequireCompleteType(atLoc, type,
+                                diag::err_incomplete_receiver_type))
+          return Diag(atLoc, diag::error_objc_synchronized_expects_object)
+                   << type << operand->getSourceRange();
+
+        ExprResult result = PerformContextuallyConvertToObjCPointer(operand);
+        if (!result.isUsable())
+          return Diag(atLoc, diag::error_objc_synchronized_expects_object)
+                   << type << operand->getSourceRange();
+
+        operand = result.get();
+      } else {
+          return Diag(atLoc, diag::error_objc_synchronized_expects_object)
+                   << type << operand->getSourceRange();
+      }
+    }
   }
 
   // The operand to @synchronized is a full-expression.
diff --git a/test/SemaObjCXX/synchronized.mm b/test/SemaObjCXX/synchronized.mm
new file mode 100644
index 0000000..37305c5
--- /dev/null
+++ b/test/SemaObjCXX/synchronized.mm
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-objc-root-class %s
+
+@interface PBXTrackableTaskManager @end
+@implementation PBXTrackableTaskManager @end
+
+struct x {
+  operator PBXTrackableTaskManager *() const { return 0; }
+} a;
+
+struct y {
+  operator int *() const { return 0; }
+} b;
+
+void test1() {
+  @synchronized (a) {
+  }
+
+  @synchronized (b) {  // expected-error {{@synchronized requires an Objective-C object type ('struct y' invalid)}}
+  }
+}