1 files changed, 10 insertions, 2 deletions
diff --git a/include/clang/Serialization/ContinuousRangeMap.h b/include/clang/Serialization/ContinuousRangeMap.h
index f8ef8a1a63cf..5f8ae1fe7bee 100644
--- a/include/clang/Serialization/ContinuousRangeMap.h
+++ b/include/clang/Serialization/ContinuousRangeMap.h
@@ -12,8 +12,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_CLANG_SERIALIZATION_CONTINUOUS_RANGE_MAP_H
-#define LLVM_CLANG_SERIALIZATION_CONTINUOUS_RANGE_MAP_H
+#ifndef LLVM_CLANG_SERIALIZATION_CONTINUOUSRANGEMAP_H
+#define LLVM_CLANG_SERIALIZATION_CONTINUOUSRANGEMAP_H
 
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/SmallVector.h"
@@ -117,6 +117,14 @@ public:
     
     ~Builder() {
       std::sort(Self.Rep.begin(), Self.Rep.end(), Compare());
+      std::unique(Self.Rep.begin(), Self.Rep.end(),
+                  [](const_reference A, const_reference B) {
+        // FIXME: we should not allow any duplicate keys, but there are a lot of
+        // duplicate 0 -> 0 mappings to remove first.
+        assert((A == B || A.first != B.first) &&
+               "ContinuousRangeMap::Builder given non-unique keys");
+        return A == B;
+      });
     }
     
     void insert(const value_type &Val) {