diff --git a/lib/Checker/Checker.cpp b/lib/Checker/Checker.cpp
new file mode 100644
index 0000000..36323b9
--- /dev/null
+++ b/lib/Checker/Checker.cpp
@@ -0,0 +1,35 @@
+//== Checker.h - Abstract interface for checkers -----------------*- C++ -*--=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines Checker and CheckerVisitor, classes used for creating
+//  domain-specific checks.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Checker/PathSensitive/Checker.h"
+using namespace clang;
+
+Checker::~Checker() {}
+
+CheckerContext::~CheckerContext() {
+  // Do we need to autotransition?  'Dst' can get populated in a variety of
+  // ways, including 'addTransition()' adding the predecessor node to Dst
+  // without actually generated a new node.  We also shouldn't autotransition
+  // if we are building sinks or we generated a node and decided to not
+  // add it as a transition.
+  if (Dst.size() == size && !B.BuildSinks && !B.HasGeneratedNode) {
+    if (ST && ST != B.GetState(Pred)) {
+      static int autoTransitionTag = 0;
+      B.Tag = &autoTransitionTag;
+      addTransition(ST);
+    }
+    else
+      Dst.Add(Pred);
+  }
+}