[boost] [type_erasure]bug in computed_bases?

Subject: [boost] [type_erasure]bug in computed_bases?
From: Larry Evans (cppljevans_at_[hidden])
Date: 2012-08-27 20:39:33

Based on the output of the test code(compute_bases.cpp) in the 1st
attachment, the compute_bases metafunction defined in any.hpp is
producing something like:

  concept_interface
  < concepts
  , concept_interface
    < mpl::at_c<concepts,1>::type
    , concept_interface
      < mpl::at_c<concepts,2>::type
      , ID
      , Enable
      >
    , ID
    , Enable
    >
  , ID
  , Enable
  >

where concepts is the Concept argument to any.

When the test code is run with:

  //#define OVERLOAD_SIMPLE

the output is what should be expected with

  a_any.simple();

calling the simple<.>::apply static method.
The output for this case is shown in the
compute_bases.not_overload_simple.out.

OTOH, when the test code is run with:

  #define OVERLOAD_SIMPLE

the code in the concept_interface<typename
requirements<C>::type,...>::simple is run.
The output for this case is shown in the
compute_bases.yes_overload_simple.out.
This output shows that the concept_interface<C,...>
CTOR is called where C ==  mpl::vector<...>.

Is this the intended behaviour?  If so, where is this spelled out in
the documentation?  The documentation here:

http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/doc/html/boost_typeerasure/concept.html#boost_typeerasure.concept.custom

certainly doesn't suggest anything of that sort, and the doc here:

http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/doc/html/boost/type_erasure/concept_interface.html

says:

  1. typename Concept

     The concept that we're specializing concept_interface for.

which uses the singular Concept instead of the plural Concepts,
suggesting the Concept is not an mpl::vector<> of any sort.

-regards,
Larry