Re: [Boost-bugs] [Boost C++ Libraries] #9799: polymorphic_downcast does not support virtual inheritance

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9799: polymorphic_downcast does not support virtual inheritance
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-03-20 17:34:20

#9799: polymorphic_downcast does not support virtual inheritance
-------------------------------------------+---------------------------
  Reporter:  Camille Gillot <k1000.jlo@…>  |      Owner:  no-maintainer
      Type:  Patches                       |     Status:  closed
 Milestone:  To Be Determined              |  Component:  utility
   Version:  Boost 1.54.0                  |   Severity:  Problem
Resolution:  wontfix                       |   Keywords:
-------------------------------------------+---------------------------
Changes (by steven_watanabe):

 * status:  new => closed
 * resolution:   => wontfix

Comment:

 The real question is whether should this be supported.

 From the documentation: "... or when efficiency is not important,
 polymorphic_cast is preferred."  Since we have to do a dynamic_cast
 anyway, efficiency really doesn't matter.

 It's also clear that the behavior is consistent with the documentation:

 {{{
 #!c++
 template <class Derived, class Base>
 inline Derived polymorphic_downcast(Base* x);
 // Effects: assert( dynamic_cast<Derived>(x) == x );
 // Returns: static_cast<Derived>(x)
 }}}

 Also, your patch doesn't compile.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9799#comment:1>
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