Andreas Huber wrote: > Hi Aleksey & all other metaprogramming gurus
Hi Andreas, > > The attached code compiles just fine with MSVC7.1 but MSVC7.0 once more has > its problems. This time I'm quite sure it has nothing to do with MPL, > instead VC7.0 seems to get confused and reports the following: > > d:\Data\StopWatch\StopWatch.cpp(58) : error C2516: > 'state_base_type<Derived,Context,Transitions,InnerInitial>::type' : is not a > legal base class > > According to the docs this error is reported when you try to inherit from > built-in types like int. > If you then remove the 3 first characters of the lines marked with // *** > here ***, the program compiles and you can see in the debugger that the > result returned by the metafunction state_base_type is quite a legal base > class (see type of pWhatever). > > Has anyone else ever encountered similar problems with either 7.0 or 6.5? Yep, it's a known bug called "early template instantiation" (ETI). It's briefly described here - http://lists.boost.org/MailArchives/boost/msg39915.php. > Are there any workarounds? Sure. In your case, it would be as simple as this: #include <boost/mpl/aux_/msvc_eti_base.hpp> ... template< class Derived, class Context, class Transitions = empty_list, class InnerInitial = empty_list > class simple_state : public mpl::aux::msvc_eti_base< typename state_base_type< // ^^^^^^^^^^^^^^^^^^^^^^^^ Derived, Context, Transitions, InnerInitial >::type >::type {}; You will need the latest CVS for that, though. Aleksey _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
