Re: [boost] Pointers to member function templates as template arguments

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2005-06-01 20:16:59

On Jun 1, 2005, at 6:31 PM, Jonathan Turkanis wrote:

> Hi,
>
> Consider the following code:
>
>   template<typename T, void (T::*) (int)>
>   struct MemFn;
>
>   struct Foo {
>      template<typename Int>
>      void bar(Int) { }
>   };
>
>   typedef MemFn<Foo, &Foo::bar> type;
>
> This compiles with VC7.1, GCC 3.4, Intel 8.0 and Comeau 4.3.3 in 
> strict mode,
> but CodeWarrior 9.4 fails with the message:
>
>   Error   : illegal implicit member pointer conversion
>   example.cpp line 9   typedef MemFn<Foo, &Foo::bar> type;
>
> Looking at 14.3.2/1, I notice while the third bullet, on function 
> pointers,
> explicitly mentions templates, the fourth bullet, on pointers to 
> members,
> doesn't. But perhaps pointers to function templates are covered 
> implicitly.
>
> Looking at 14.3.2/5, bullet 6, I see that no conversions are applied 
> to pointers
> to members. But no conversions are needed in the above example. What's 
> needed is
> overload resolution, which is explicitly allowed.
>
> So who's right -- Metrowerks or everyone else?

I believe everyone else is.  This snippet compiles on a more recent 
internal compiler.

I looked around for a workaround, but haven't come up with one yet.

-Howard