2 files changed, 53 insertions, 9 deletions
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index fad0fe14c24..0f3e553ae27 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -2675,16 +2675,21 @@ ASTReader::ASTReadResult ASTReader::ReadAST(const std::string &FileName,
   // Bump the generation number.
   unsigned PreviousGeneration = CurrentGeneration++;
 
-  // Load the core of the AST files.
+  unsigned NumModules = ModuleMgr.size();
   llvm::SmallVector<ModuleFile *, 4> Loaded;
-  switch(ReadASTCore(FileName, Type, /*ImportedBy=*/0, Loaded,
-                     ClientLoadCapabilities)) {
-  case Failure: return Failure;
-  case OutOfDate: return OutOfDate;
-  case VersionMismatch: return VersionMismatch;
-  case ConfigurationMismatch: return ConfigurationMismatch;
-  case HadErrors: return HadErrors;
-  case Success: break;
+  switch(ASTReadResult ReadResult = ReadASTCore(FileName, Type,
+                                                /*ImportedBy=*/0, Loaded,
+                                                ClientLoadCapabilities)) {
+  case Failure:
+  case OutOfDate:
+  case VersionMismatch:
+  case ConfigurationMismatch:
+  case HadErrors:
+    ModuleMgr.removeModules(ModuleMgr.begin() + NumModules, ModuleMgr.end());
+    return ReadResult;
+
+  case Success:
+    break;
   }
 
   // Here comes stuff that we only do once the entire chain is loaded.
diff --git a/clang/lib/Serialization/ModuleManager.cpp b/clang/lib/Serialization/ModuleManager.cpp
index c46e9f06083..efe442101bb 100644
--- a/clang/lib/Serialization/ModuleManager.cpp
+++ b/clang/lib/Serialization/ModuleManager.cpp
@@ -88,6 +88,45 @@ ModuleManager::addModule(StringRef FileName, ModuleKind Type,
   return std::make_pair(ModuleEntry, NewModule);
 }
 
+namespace {
+  /// \brief Predicate that checks whether a module file occurs within
+  /// the given set.
+  class IsInModuleFileSet : public std::unary_function<ModuleFile *, bool> {
+    llvm::SmallPtrSet<ModuleFile *, 4> &Removed;
+
+  public:
+    IsInModuleFileSet(llvm::SmallPtrSet<ModuleFile *, 4> &Removed)
+    : Removed(Removed) { }
+
+    bool operator()(ModuleFile *MF) const {
+      return Removed.count(MF);
+    }
+  };
+}
+
+void ModuleManager::removeModules(ModuleIterator first, ModuleIterator last) {
+  if (first == last)
+    return;
+
+  // Collect the set of module file pointers that we'll be removing.
+  llvm::SmallPtrSet<ModuleFile *, 4> victimSet(first, last);
+
+  // Remove any references to the now-destroyed modules.
+  IsInModuleFileSet checkInSet(victimSet);
+  for (unsigned i = 0, n = Chain.size(); i != n; ++i) {
+    Chain[i]->ImportedBy.remove_if(checkInSet);
+  }
+
+  // Delete the modules and erase them from the various structures.
+  for (ModuleIterator victim = first; victim != last; ++victim) {
+    Modules.erase((*victim)->File);
+    delete *victim;
+  }
+
+  // Remove the modules from the chain.
+  Chain.erase(first, last);
+}
+
 void ModuleManager::addInMemoryBuffer(StringRef FileName, 
                                       llvm::MemoryBuffer *Buffer) {