[boost] Problem with detail/identifier.hpp

From: Matthias Troyer (troyer_at_[hidden])
Date: 2006-11-12 08:27:34

Hi Beman, hi all

Due to recent changes to the filesystem library now, the header  
detail/identifier.hpp is now included in my projects and contains the  
dangerous code segment:

   template <class Ostream, class Id>
     typename enable_if< is_base_of< identifier< typename  
Id::value_type, Id >, Id >,
       Ostream & >::type operator<<( Ostream & os, const Id & id )
   {
     return os << id.value();
   }

which breaks all of my codes, since I have a type Id, that has a type  
member Id::value_type which is an abstract base class. My compiler  
(Apple gcc-4.0) now tries to instantiate identifier< typename  
Id::value_type, Id >, which fails because Id::value_type is abstract,  
and the compiler aborts with an error message.

This causes all of our codes to fail to compile with the current CVS  
head

Matthias