[incrParse] Support incremental parsing for edited files

include/swift/AST/Module.h

@@ -28,6 +28,7 @@
 #include "swift/Basic/OptionSet.h"
 #include "swift/Basic/STLExtras.h"
 #include "swift/Basic/SourceLoc.h"
+#include "swift/Parse/SyntaxParsingCache.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
@@ -838,6 +839,10 @@ public:
   /// The list of top-level declarations in the source file.
   std::vector<Decl*> Decls;
 
+  /// A cache of syntax nodes that can be reused when creating the syntax tree
+  /// for this file.
+  SyntaxParsingCache *SyntaxParsingCache = nullptr;
+
   /// The list of local type declarations in the source file.
   llvm::SetVector<TypeDecl *> LocalTypeDecls;