Re: [Boost-bugs] [Boost C++ Libraries] #9201: CopyConstructible, as a side effect, requires the type to be DefaultConstructible.

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #9201: CopyConstructible, as a side effect, requires the type to be DefaultConstructible.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-02-18 12:37:14

#9201: CopyConstructible, as a side effect, requires the type to be
DefaultConstructible.
-------------------------------------+-------------------------------------
  Reporter:  David Laštovička        |      Owner:  jsiek
  <david@…>                          |     Status:  new
      Type:  Bugs                    |  Component:  concept_check
 Milestone:  To Be Determined        |   Severity:  Problem
   Version:  Boost Development       |   Keywords:  concept
  Trunk                              |  CopyConstructible
Resolution:                          |  DefaultConstructible Assignable
-------------------------------------+-------------------------------------

Comment (by acharles):

 I think the only way to fix this is to have the following approach:

 TT* b_ptr = NULL;
 if (b_ptr) {
   TT& b = *b_ptr;
   TT a(b); // Though I wonder if this shouldn't require an implicit copy
 constructor.
   TT* ptr = &a;
   ...
 }

 This is the only way I can think of to create an object of type TT without
 relying on default construction, while also not invoking undefined
 behavior and also having it require compilation.

 Is there a better idea?

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9201#comment:1>
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