Re: [boost] Holiday homework (was: C++ millenium challenge solved?)

From: Matthias Troyer (troyer_at_[hidden])
Date: 2005-12-30 05:56:49

On Dec 28, 2005, at 8:34 PM, Eric Niebler wrote:

>
> You can help improve Boost.Foreach and Boost.Typeof for your  
> favorite compiler! Read on.
>
> Eric Niebler wrote:
>> Thorsten Ottosen wrote:
>>>
>>> Now it works on vc7.1 too.
>> getting this to work with vc7.1 is a major advance. Thanks.
>
> I am now using the compile-time-const-rvalue-detection trick in the  
> new-and-improved BOOST_FOREACH. For the first time, it's passing  
> its tests at 100% for VC7.1 and VC8. Also, const rvalues are being  
> detected on gcc 3.4+ with zero runtime overhead. Very nice!
>
> OK, now here's a simple thing anybody can do to improve Foreach and  
> Typeof. Try compiling the attached file on your favorite compiler  
> and report the results. I already know it works for VC7.1+ and gcc  
> 3.4+. Everything else is up for grabs.

IBM Visual Age C++ version 6 and 7 gives the following compile time  
error:

  line 68.17: 1540-0135 (S) The array bound cannot be zero.

Adding 1 to all the array sizes gives the following error:

line 22.40: 1540-0704 (S) The definitions of
"boost::mpl::and_<boost::mpl::not_<boost::is_array<foo>  
 >,mpl_::bool_<1==sizeof((impl_::is_true(impl_::is_rvalue((1 ?  
impl_::make_probe(cf)..." and
"boost::mpl::and_<boost::mpl::not_<boost::is_array<foo>  
 >,mpl_::bool_<1==sizeof((impl_::is_true(impl_::is_rvalue((1 ?  
impl_::make_probe(mak..."
have the same linkage signature
"and___5impl_HQ3_5boost3mpl4not_XTQ2_5boost8is_arrayXT3foo__Q2_4mpl_5boo 
l_XSP0__PQ3_5boost3mpl4not_XTQ2_5boost8is_arrayXT3foo__PQ2_4mpl_5bo...".

> Extra credit #1: If it doesn't compile for you, patch it so it  
> does. :-)
>
> Extra credit #2: Find a formulation that is 100% standard  
> compliant. Back up your claim by citing references from the  
> standard. :-)))

I'll do that when I find some time.

Matthias