3 files changed, 11 insertions, 1 deletions
diff --git a/clang/include/clang/Basic/DiagnosticSerializationKinds.td b/clang/include/clang/Basic/DiagnosticSerializationKinds.td
index fe5fd00d737..f28f9983d0e 100644
--- a/clang/include/clang/Basic/DiagnosticSerializationKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSerializationKinds.td
@@ -41,6 +41,8 @@ def err_pch_langopt_value_mismatch : Error<
   "%0 differs in PCH file vs. current file">;
 def err_pch_diagopt_mismatch : Error<"%0 is currently enabled, but was not in "
   "the PCH file">;
+def err_pch_modulecache_mismatch : Error<"PCH was compiled with module cache "
+  "path '%0', but the path is currently '%1'">;
   
 def err_pch_version_too_old : Error<
     "PCH file uses an older PCH format that is no longer supported">;
diff --git a/clang/include/clang/Frontend/CompilerInstance.h b/clang/include/clang/Frontend/CompilerInstance.h
index f40e115c23d..cee87b0475f 100644
--- a/clang/include/clang/Frontend/CompilerInstance.h
+++ b/clang/include/clang/Frontend/CompilerInstance.h
@@ -575,6 +575,8 @@ public:
   /// and replace any existing one with it.
   void createPreprocessor(TranslationUnitKind TUKind);
 
+  std::string getSpecificModuleCachePath();
+
   /// Create the AST context.
   void createASTContext();
 
diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index d7ecf266069..27af9995aa9 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/clang/include/clang/Serialization/ASTReader.h
@@ -153,6 +153,7 @@ public:
   /// \returns true to indicate the header search options are invalid, or false
   /// otherwise.
   virtual bool ReadHeaderSearchOptions(const HeaderSearchOptions &HSOpts,
+                                       StringRef SpecificModuleCachePath,
                                        bool Complain) {
     return false;
   }
@@ -230,6 +231,7 @@ public:
                              bool Complain) override;
 
   bool ReadHeaderSearchOptions(const HeaderSearchOptions &HSOpts,
+                               StringRef SpecificModuleCachePath,
                                bool Complain) override;
   bool ReadPreprocessorOptions(const PreprocessorOptions &PPOpts,
                                bool Complain,
@@ -261,6 +263,9 @@ public:
                              bool Complain) override;
   bool ReadPreprocessorOptions(const PreprocessorOptions &PPOpts, bool Complain,
                                std::string &SuggestedPredefines) override;
+  bool ReadHeaderSearchOptions(const HeaderSearchOptions &HSOpts,
+                               StringRef SpecificModuleCachePath,
+                               bool Complain) override;
   void ReadCounter(const serialization::ModuleFile &M, unsigned Value) override;
 
 private:
@@ -1496,7 +1501,8 @@ public:
                                   FileManager &FileMgr,
                                   const LangOptions &LangOpts,
                                   const TargetOptions &TargetOpts,
-                                  const PreprocessorOptions &PPOpts);
+                                  const PreprocessorOptions &PPOpts,
+                                  std::string ExistingModuleCachePath);
 
   /// \brief Returns the suggested contents of the predefines buffer,
   /// which contains a (typically-empty) subset of the predefines