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Re: What does the standard say about this?

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Am 16.07.2011 23:26, schrieb Evan D.:
>
> [Cross post to comp.lang.c++, but I posted it there a while back and
> haven't had any responses. This may be a better newsgroup for it
> anyway.]
>
> I have some code that I don't understand the implications of. GCC
>   4.6.1 (and the earlier versions I've tried) accept it, but EDG does
>   not (specifically, I've tried with Comeau's online front end and
> Intel
>   CC 11.0).
>
> I'm quite familiar with some of the weird name lookup issues that
>   arise when templates and dependent names are involved, but at least
> I
>   would argue that they shouldn't apply in this case. Is it a defect
> in
>   EDG that it rejects it, a defect in GCC that accepts it, or one of
>   those places where the code isn't compliant but compliers aren't
>   required to issue a diagnostic?
>
> EDG reports:
>    error: declaration is incompatible with
>   "ref_ptr<Wrapper<T>::control>
> Wrapper<T>::control::alpha()" (declared
>   at line 9)
>      Wrapper<T>::control::alpha()
>
> in this code:
>      template<  typename T>
>          class ref_ptr {
>      };
>
>     template<typename T>
>      class Wrapper {
>          class control {
>            public:
>              static ref_ptr<control>  alpha();
>          };
>          typedef ref_ptr<control>  controlRefPtr;
>      };
>
>     template<typename T>
>      typename Wrapper<T>::controlRefPtr
>      Wrapper<T>::control::alpha()
>      {
>      }

This example looks like a variant of the open core issue

http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#2

to me. Following the current non-normative state of the issue, I would
argue that your example is correctly diagnosed as ill-formed, because
the meaning of Wrapper<T>::controlRefPtr depends on the concrete
instantiation of Wrapper<T>.

HTH & Greetings from Bremen,

Daniel Krügler


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What does the standard say about this? "Evan D." <evaned@gmail.com> - 2011-07-16 15:26 -0600
  Re: What does the standard say about this? Daniel Krügler <daniel.kruegler@googlemail.com> - 2011-07-17 09:51 -0600

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