2 files changed, 11 insertions, 7 deletions
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 17296685c4e..639ef93fb6b 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -4950,8 +4950,10 @@ namespace {
           continue;
 
         if (ND->getDeclName() != This->Name) {
-          assert(!This->Name.getCXXNameType().isNull() && 
-                 "Name mismatch without a type");
+          // A name might be null because the decl's redeclarable part is
+          // currently read before reading its name. The lookup is triggered by
+          // building that decl (likely indirectly), and so it is later in the
+          // sense of "already existing" and can be ignored here.
           continue;
         }
       
diff --git a/clang/test/Modules/Inputs/redecl-merge-left.h b/clang/test/Modules/Inputs/redecl-merge-left.h
index a6ea6024c85..1f5da4f2e27 100644
--- a/clang/test/Modules/Inputs/redecl-merge-left.h
+++ b/clang/test/Modules/Inputs/redecl-merge-left.h
@@ -88,12 +88,14 @@ template<> class List<bool> {
 public:
   void push_back(int);
 };
-
 namespace N {
-template<typename T> class Set {
-public:
-  void insert(T);
-};
+  template<typename T> class Set;
+}
+namespace N {
+  template<typename T> class Set {
+  public:
+    void insert(T);
+  };
 }
 #endif