[Bug c++/25185] deep typedef substitution in error message

["dave at boostpro dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #20 from dave at boostpro dot com  2009-04-04 01:33 -------
Subject: Re:  deep typedef substitution in error message


on Fri Apr 03 2009, "jason at gcc dot gnu dot org"
<gcc-bugzilla-AT-gcc.gnu.org> wrote:

> ------- Comment #19 from jason at gcc dot gnu dot org  2009-04-03 21:45 -------
> Fixing that issue (we weren't canonicalizing deduced type arguments) and also
> catching typedefs that aren't typenames gives
>
> ../../../../boost/sequence/make_range.hpp:60:   instantiated from
> Â?boost::sequence::detail::range_maker<Elements, Begin, End, CalcSize>::type
> boost::sequence::detail::range_maker<Elements, Begin, End,
> CalcSize>::operator()(const L&, const B&, const E&, const C&) const [with L =
> boost::sequence::identity_property_map; B = char*; E = char*; C =
> boost::sequence::detail::size_difference<boost::array<char, 11u>, const
> boost::array<char, 6u> >; Elements = boost::sequence::identity_property_map;
> Begin = char*; End = char*; CalcSize =
> boost::sequence::detail::size_difference<boost::array<char, 11u>,
> boost::array<char, 6u> >; boost::sequence::detail::range_maker<Elements, Begin,
> End, CalcSize>::type =
> boost::sequence::range_::range<boost::sequence::identity_property_map, char*,
> char*, mpl_::integral_c<unsigned int, 5u> >; typename
> boost::result_of<CalcSize()>::type = mpl_::integral_c<unsigned int, 5u>]Â?
>
> Does that look better?

Hum, let me try to reformat that so I can understand it


../../../../boost/sequence/make_range.hpp:60:   instantiated from

  boost::sequence::detail::range_maker<Elements, Begin, End, CalcSize>::type
  boost::sequence::detail::range_maker<
    Elements, Begin, End, CalcSize
  >::operator()(const L&, const B&, const E&, const C&) const 
  [with 
     L = boost::sequence::identity_property_map; 
     B = char*; 
     E = char*; 
     C = boost::sequence::detail::size_difference<
          boost::array<char, 11u>, const boost::array<char, 6u> >; 
     Elements = boost::sequence::identity_property_map;
    Begin = char*; 
    End = char*; 
    CalcSize = boost::sequence::detail::size_difference<
          boost::array<char, 11u>, boost::array<char, 6u> >; 
    boost::sequence::detail::range_maker<Elements, Begin, End, CalcSize>::type
      = boost::sequence::range_::range<
          boost::sequence::identity_property_map, char*, char*, 
          mpl_::integral_c<unsigned int, 5u> >; 
    typename boost::result_of<CalcSize()>::type = mpl_::integral_c<unsigned
int, 5u>
  ]

Well, I find that a little confusing.  Why is it explaining to me what

  typename boost::result_of<CalcSize()>::type 

is?  I don't see that type anywhere else in there.  Also, I'm not
thrilled that

  boost::sequence::detail::range_maker<Elements, Begin, End, CalcSize>::type

is still present in the signature, even if it's explained below.
Carried to an extreme, you get EDG's nasty nested 

  ={...={...={...}}} 

type descriptions.  Do you need to do that?  Why not just spell out the
return type?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25185