Re: [boost] [typeof] function references and gcc 3.3.5

From: Tobias Schwinger (tschwinger_at_[hidden])
Date: 2006-01-06 14:51:29

Alexander Nasonov wrote:
> The following code doesn't compile on gcc 3.3.5
> 
> typedef int (fun)(bool);
> fun& foo();
> 
> BOOST_STATIC_ASSERT((boost::is_same<BOOST_TYPEOF(foo()), fun>::value));
> 
> The error is
> 
> error: no matching function for call to `ensure_obj(int(&)(bool))'
> 
> This can be fixed by introducing more specialized ensure_obj:
> 
> template<class T> T& ensure_obj(const T&, int);
> template<class R, class T0> R(& ensure_obj(R (&)(T0), ...) )(T0);
> template<class R, class T0, class T1> R(& ensure_obj(R (&)(T0,T1), ...) 
> )(T0,T1);
> // ...
> 

Sorry for jumping in here. But I believe that

     #ifndef BOOST_NO_SFINAE
     namespace boost { namespace type_of {
       template<typename T>
       typename enable_if<is_function<T>, T &>::type
       ensure_obj(T &);
     } }
     #endif
     // verified to solve the problem with GCC 3.2.3

is a much nicer solution to the problem you describe (because it leaves 
scalability up to boost::is_function).

Best,

Tobias