6 files changed, 71 insertions, 5 deletions
diff --git a/clang/include/clang/Serialization/ASTWriter.h b/clang/include/clang/Serialization/ASTWriter.h
index 6bdba097c9b..b8bff27f57e 100644
--- a/clang/include/clang/Serialization/ASTWriter.h
+++ b/clang/include/clang/Serialization/ASTWriter.h
@@ -217,6 +217,16 @@ private:
   llvm::SmallVector<std::pair<serialization::DeclID, uint64_t>, 16>
       ReplacedDecls;
 
+  typedef llvm::SmallVector<serialization::DeclID, 4>
+      AdditionalTemplateSpecializationsList;
+  typedef llvm::DenseMap<serialization::DeclID,
+                         AdditionalTemplateSpecializationsList>
+      AdditionalTemplateSpecializationsMap;
+
+  /// \brief Additional specializations (including partial) of templates that
+  /// were introduced after the template was serialized.
+  AdditionalTemplateSpecializationsMap AdditionalTemplateSpecializations;
+
   /// \brief Statements that we've encountered while serializing a
   /// declaration or type.
   llvm::SmallVector<Stmt *, 16> StmtsToEmit;
@@ -266,6 +276,7 @@ private:
   void WriteAttributeRecord(const AttrVec &Attrs);
   void WriteDeclUpdateBlock();
   void WriteDeclContextVisibleUpdate(const DeclContext *DC);
+  void WriteAdditionalTemplateSpecializations();
 
   unsigned ParmVarDeclAbbrev;
   unsigned DeclContextLexicalAbbrev;
@@ -420,6 +431,13 @@ public:
     UpdatedNamespaces.insert(NS);
   }
 
+  /// \brief Record a template specialization or partial specialization of
+  /// a template from a previous PCH file.
+  void AddAdditionalTemplateSpecialization(serialization::DeclID Templ,
+                                           serialization::DeclID Spec) {
+    AdditionalTemplateSpecializations[Templ].push_back(Spec);
+  }
+
   /// \brief Note that the identifier II occurs at the given offset
   /// within the identifier table.
   void SetIdentifierOffset(const IdentifierInfo *II, uint32_t Offset);
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 5c3e24a0a27..be181f44069 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -2129,6 +2129,21 @@ void ASTWriter::WriteDeclContextVisibleUpdate(const DeclContext *DC) {
   Stream.EmitRecordWithBlob(UpdateVisibleAbbrev, Record, LookupTable.str());
 }
 
+/// \brief Write ADDITIONAL_TEMPLATE_SPECIALIZATIONS blocks for all templates
+/// that have new specializations in the current AST file.
+void ASTWriter::WriteAdditionalTemplateSpecializations() {
+  RecordData Record;
+  for (AdditionalTemplateSpecializationsMap::iterator
+           I = AdditionalTemplateSpecializations.begin(),
+           E = AdditionalTemplateSpecializations.end();
+       I != E; ++I) {
+    Record.clear();
+    Record.push_back(I->first);
+    Record.insert(Record.end(), I->second.begin(), I->second.end());
+    Stream.EmitRecord(ADDITIONAL_TEMPLATE_SPECIALIZATIONS, Record);
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // General Serialization Routines
 //===----------------------------------------------------------------------===//
@@ -2638,6 +2653,10 @@ void ASTWriter::WriteASTChain(Sema &SemaRef, MemorizeStatCalls *StatCalls,
          I != E; ++I)
     WriteDeclContextVisibleUpdate(*I);
 
+  // Write the updates to C++ template specialization lists.
+  if (!AdditionalTemplateSpecializations.empty())
+    WriteAdditionalTemplateSpecializations();
+
   Record.clear();
   Record.push_back(NumStatements);
   Record.push_back(NumMacros);
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 3edb6302f8f..413f544f4c1 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -888,13 +888,21 @@ void ASTDeclWriter::VisitClassTemplateSpecializationDecl(
   llvm::PointerUnion<ClassTemplateDecl *,
                      ClassTemplatePartialSpecializationDecl *> InstFrom
     = D->getSpecializedTemplateOrPartial();
+  Decl *InstFromD;
   if (InstFrom.is<ClassTemplateDecl *>()) {
-    Writer.AddDeclRef(InstFrom.get<ClassTemplateDecl *>(), Record);
+    InstFromD = InstFrom.get<ClassTemplateDecl *>();
+    Writer.AddDeclRef(InstFromD, Record);
   } else {
-    Writer.AddDeclRef(InstFrom.get<ClassTemplatePartialSpecializationDecl *>(),
-                      Record);
+    InstFromD = InstFrom.get<ClassTemplatePartialSpecializationDecl *>();
+    Writer.AddDeclRef(InstFromD, Record);
     Writer.AddTemplateArgumentList(&D->getTemplateInstantiationArgs(), Record);
+    InstFromD = cast<ClassTemplatePartialSpecializationDecl>(InstFromD)->
+                    getSpecializedTemplate();
   }
+  // Is this a specialization of an already-serialized template?
+  if (InstFromD->getCanonicalDecl()->getPCHLevel() != 0)
+    Writer.AddAdditionalTemplateSpecialization(Writer.getDeclID(InstFromD),
+                                               Writer.getDeclID(D));
 
   // Explicit info.
   Writer.AddTypeSourceInfo(D->getTypeAsWritten(), Record);
diff --git a/clang/test/PCH/Inputs/chain-cxx1.h b/clang/test/PCH/Inputs/chain-cxx1.h
index 747bdbc7f42..7ea3ffb61c8 100644
--- a/clang/test/PCH/Inputs/chain-cxx1.h
+++ b/clang/test/PCH/Inputs/chain-cxx1.h
@@ -12,4 +12,8 @@ namespace ns {
 }
 
 template <typename T>
-struct S {};
+struct S { typedef int G; };
+
+// Partially specialize
+template <typename T>
+struct S<T *> { typedef int H; };
diff --git a/clang/test/PCH/Inputs/chain-cxx2.h b/clang/test/PCH/Inputs/chain-cxx2.h
index ff22e538d4d..adc10fd8368 100644
--- a/clang/test/PCH/Inputs/chain-cxx2.h
+++ b/clang/test/PCH/Inputs/chain-cxx2.h
@@ -18,3 +18,15 @@ namespace ns {
 // Specialize template from primary
 template <>
 struct S<int> { typedef int I; };
+
+// Partially specialize
+template <typename T>
+struct S<T &> { typedef int J; };
+
+// Specialize previous partial specialization
+template <>
+struct S<int *> { typedef int K; };
+
+// Specialize the partial specialization from this file
+template <>
+struct S<int &> { typedef int L; };
diff --git a/clang/test/PCH/chain-cxx.cpp b/clang/test/PCH/chain-cxx.cpp
index 450a7918286..3e46214c70b 100644
--- a/clang/test/PCH/chain-cxx.cpp
+++ b/clang/test/PCH/chain-cxx.cpp
@@ -19,5 +19,10 @@ void test() {
   ns::pg();
   ns::g2();
 
-  //typedef S<int>::I J;
+  typedef S<double>::G T1;
+  typedef S<double *>::H T2;
+  typedef S<int>::I T3;
+  typedef S<double &>::J T4;
+  typedef S<int *>::K T5;
+  typedef S<int &>::L T6;
 }