Re: [boost] Is there any interest in a casting library where you don't need to specify a type of receiver?

From: Sergey Shandar (sergey_at_[hidden])
Date: 2007-11-28 19:09:37

shunsuke wrote:
> Sergey Shandar wrote:
>   
>> 3. I found this one today:
>>
>>     template<class T>
>>     operator T &() const
>>         throw(typename ::boost::disable_if< ::boost::is_same<T, MyClass 
>> const> >::type *)
>>     
>
> You've solved the millenium problem! :-)
>
> gcc3.4.5 and 4.1.2 seem to work fine.
> Thanks!
>
>
>   
According to the standard, the code should not work.

14.8.2.2

    - All references in the function type of the function template to the
corresponding template parameters are replaced by the specified template
argument values. If a substitution in a template parameter or in the function
type of the function template results in an invalid type, type deduction fails.
[Note: *The equivalent substitution in exception specifications is done only
when the function is instantiated, at which point a program is ill-formed if
the substitution results in an invalid type.*] Type deduction may fail for the
following reasons:

However, it works on GCC. So, the workaround uses just another bug in 
GCC :-)