No virtual destructor in ExternalSemaSource

Hi all,
   I found out that there is no virtual destructor for ExternalSemaSource:
     include/clang/Sema/ExternalSemaSource.h:33: ~ExternalSemaSource();
     include/clang/AST/ExternalASTSource.h:56: virtual ~ExternalASTSource();

   Is that bug or I am misunderstanding something? Shall we (Axel Naumann and me) check in patch.
Cheers,
Vassil

Methods with the same signature as virtual methods in a base class are
implicitly virtual, and this applies to destructors, too.

John.

Oh crap... I forgot that ExternalSemaSource derives from ExternalASTSource.
Vassil