7 files changed, 58 insertions, 13 deletions
diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index ecc73c97fc..e0950192e3 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -290,8 +290,17 @@ private:
   /// in the chain.
   DeclUpdateOffsetsMap DeclUpdateOffsets;
 
-  typedef llvm::DenseMap<serialization::DeclID,
-                         std::pair<Module *, uint64_t> >
+  struct ReplacedDeclInfo {
+    Module *Mod;
+    uint64_t Offset;
+    unsigned RawLoc;
+
+    ReplacedDeclInfo() : Mod(0), Offset(0), RawLoc(0) {}
+    ReplacedDeclInfo(Module *Mod, uint64_t Offset, unsigned RawLoc)
+      : Mod(Mod), Offset(Offset), RawLoc(RawLoc) {}
+  };
+
+  typedef llvm::DenseMap<serialization::DeclID, ReplacedDeclInfo>
       DeclReplacementMap;
   /// \brief Declarations that have been replaced in a later file in the chain.
   DeclReplacementMap ReplacedDecls;
diff --git a/include/clang/Serialization/ASTWriter.h b/include/clang/Serialization/ASTWriter.h
index bad5c379bc..8c0ea4fc33 100644
--- a/include/clang/Serialization/ASTWriter.h
+++ b/include/clang/Serialization/ASTWriter.h
@@ -286,14 +286,24 @@ private:
   /// another module.
   SmallVector<ChainedObjCCategoriesData, 16> LocalChainedObjCCategories;
 
+  struct ReplacedDeclInfo {
+    serialization::DeclID ID;
+    uint64_t Offset;
+    unsigned Loc;
+
+    ReplacedDeclInfo() : ID(0), Offset(0), Loc(0) {}
+    ReplacedDeclInfo(serialization::DeclID ID, uint64_t Offset,
+                     SourceLocation Loc)
+      : ID(ID), Offset(Offset), Loc(Loc.getRawEncoding()) {}
+  };
+
   /// \brief Decls that have been replaced in the current dependent AST file.
   ///
   /// When a decl changes fundamentally after being deserialized (this shouldn't
   /// happen, but the ObjC AST nodes are designed this way), it will be
   /// serialized again. In this case, it is registered here, so that the reader
   /// knows to read the updated version.
-  SmallVector<std::pair<serialization::DeclID, uint64_t>, 16>
-      ReplacedDecls;
+  SmallVector<ReplacedDeclInfo, 16> ReplacedDecls;
 
   /// \brief Statements that we've encountered while serializing a
   /// declaration or type.
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 7ae0c42069..4554f05256 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2217,13 +2217,13 @@ ASTReader::ReadASTBlock(Module &F) {
     }
 
     case DECL_REPLACEMENTS: {
-      if (Record.size() % 2 != 0) {
+      if (Record.size() % 3 != 0) {
         Error("invalid DECL_REPLACEMENTS block in AST file");
         return Failure;
       }
-      for (unsigned I = 0, N = Record.size(); I != N; I += 2)
+      for (unsigned I = 0, N = Record.size(); I != N; I += 3)
         ReplacedDecls[getGlobalDeclID(F, Record[I])]
-          = std::make_pair(&F, Record[I+1]);
+          = ReplacedDeclInfo(&F, Record[I+1], Record[I+2]);
       break;
     }
 
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 7b37bbfa1b..d414c07290 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -1449,8 +1449,10 @@ ASTReader::RecordLocation
 ASTReader::DeclCursorForID(DeclID ID, unsigned &RawLocation) {
   // See if there's an override.
   DeclReplacementMap::iterator It = ReplacedDecls.find(ID);
-  if (It != ReplacedDecls.end())
-    return RecordLocation(It->second.first, It->second.second);
+  if (It != ReplacedDecls.end()) {
+    RawLocation = It->second.RawLoc;
+    return RecordLocation(It->second.Mod, It->second.Offset);
+  }
 
   GlobalDeclMapType::iterator I = GlobalDeclMap.find(ID);
   assert(I != GlobalDeclMap.end() && "Corrupted global declaration map");
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 1b44baa9ce..9716447dfa 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -3234,10 +3234,11 @@ void ASTWriter::WriteDeclReplacementsBlock() {
     return;
 
   RecordData Record;
-  for (SmallVector<std::pair<DeclID, uint64_t>, 16>::iterator
+  for (SmallVector<ReplacedDeclInfo, 16>::iterator
            I = ReplacedDecls.begin(), E = ReplacedDecls.end(); I != E; ++I) {
-    Record.push_back(I->first);
-    Record.push_back(I->second);
+    Record.push_back(I->ID);
+    Record.push_back(I->Offset);
+    Record.push_back(I->Loc);
   }
   Stream.EmitRecord(DECL_REPLACEMENTS, Record);
 }
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 3e3e28dfbb..c35d4b0d22 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -1647,7 +1647,8 @@ void ASTWriter::WriteDecl(ASTContext &Context, Decl *D) {
 
   if (ID < FirstDeclID) {
     // We're replacing a decl in a previous file.
-    ReplacedDecls.push_back(std::make_pair(ID, Stream.GetCurrentBitNo()));
+    ReplacedDecls.push_back(ReplacedDeclInfo(ID, Stream.GetCurrentBitNo(),
+                                             D->getLocation()));
   } else {
     unsigned Index = ID - FirstDeclID;
 
diff --git a/test/PCH/replaced-decl.m b/test/PCH/replaced-decl.m
new file mode 100644
index 0000000000..b9fee950d7
--- /dev/null
+++ b/test/PCH/replaced-decl.m
@@ -0,0 +1,22 @@
+// Without PCH
+// RUN: %clang_cc1 -fsyntax-only -verify %s -include %s -include %s
+
+// With PCH
+// RUN: %clang_cc1 -fsyntax-only -verify %s -chain-include %s -chain-include %s
+
+#ifndef HEADER1
+#define HEADER1
+
+@class I;
+
+#elif !defined(HEADER2)
+#define HEADER2
+
+@interface I // expected-note {{previous}}
+@end
+
+#else
+
+typedef int I; // expected-error {{redefinition}}
+
+#endif