gcc-4.0 non-local variable uses anonymous type warning

[William S Fulton]

Does anyone know the point of the following warning, introduced with 
gcc-4.0:

test.cxx:15: warning: non-local variable ‘<unnamed>::<anonymous enum> 
<unnamed>::InstanceÂ’ uses anonymous type

for this code:

   namespace {
     enum { foo, bar = 10 } Instance;
   }

Gcc issues this with default warning levels for enums and classes, 
whether or not the anonymously declared type is declared within an 
anonymous namespace. What is the point of the warning? Is there anything 
wrong with using an anonymous type? How is it different to this, which 
doesn't issue the warning:

   static enum { foo, bar = 10 } Instance;

Thanks,

William