 +  Sources.push_back(&source);
 +}
 +
-+//===-----------------------------------------------------------------------===//
++//===----------------------------------------------------------------------===//
 +// ExternalASTSource.
-+//===-----------------------------------------------------------------------===//
++//===----------------------------------------------------------------------===//
 +
 +Decl *MultiplexExternalSemaSource::GetExternalDecl(uint32_t ID) {
 +  for(size_t i = 0; i < Sources.size(); ++i)

+  /// out according to the ABI.
+  ///
+  /// \param VirtualBaseOffsets The offset of each of the virtual base classes
+  /// (either direct or not). If any bases are not given offsets, the bases will be laid 
+  /// out according to the ABI.
+  /// 
+  /// \returns true if the record layout was provided, false otherwise.
+  virtual bool 

+  /// may be invoked multiple times; the external source should take care not 
+  /// to introduce the same selectors repeatedly.
+  virtual void ReadReferencedSelectors(SmallVectorImpl<std::pair<Selector, 
+                                                       SourceLocation> > &Sels);
+
+  /// \brief Read the set of weak, undeclared identifiers known to the
+  /// external Sema source.
