[Boost-bugs] [Boost C++ Libraries] #5483: value_init: Assignment to 'value_initialized', 'initialized' objects doesn't work automatically

Subject: [Boost-bugs] [Boost C++ Libraries] #5483: value_init: Assignment to 'value_initialized', 'initialized' objects doesn't work automatically
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-04-16 03:25:30

#5483: value_init: Assignment to 'value_initialized', 'initialized' objects
doesn't work automatically
-----------------------------------------------------+----------------------
 Reporter:  Christian Masloch <cm@…>                 |       Owner:  no-maintainer
     Type:  Bugs                                     |      Status:  new          
Milestone:  To Be Determined                         |   Component:  utility      
  Version:  Boost 1.46.1                             |    Severity:  Problem      
 Keywords:                                           |  
-----------------------------------------------------+----------------------
 Objects of the 'initialized<T>' class (and presumably
 'value_initialized<T>' too) do not automatically convert to assignment
 lvalues and do not provide proper assignment operator methods either.
 Assignments therefore do not automatically work, for example, declaring
 'initialized<int> i;' then writing 'i = 1;'.

 Tested on Windows XP SP3 with MinGW g++ 4.4.1, as well as the (VS 2008)
 Visual C++ 9.0 compiler. Both compilers report that no match for operator=
 can be found in that assignment, and that the method 'initialized<int>&
 initialized<int>::operator=(initialized<int> const&)' is considered as
 'candidate' that would fit with a conversion inbetween (from 'int' to
 'initialized<int>'), but it's not being used. Conversion operators such as
 the one defined as 'initialized<int>::operator int&()' apparently do not
 automatically qualify for lvalues either.

 Workarounds specify the necessary conversion or operator method, for
 example, 'i.operator int&() = 1;' and 'get(i) = 1;' both work.

 The attached file contains some tests as well as a class implementing a
 simplified version of the interface of 'initialized<T>' with a fix. The
 file also contains the error message from g++. I omitted the one from
 Visual C++ (because I would have to translate it into English) but it
 essentially says the same.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/5483>
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