[Boost-bugs] [Boost C++ Libraries] #13208: Make boost::optional<T> trivially destructible, copyable and movable if T is

Subject: [Boost-bugs] [Boost C++ Libraries] #13208: Make boost::optional<T> trivially destructible, copyable and movable if T is
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2017-09-13 09:59:39

#13208: Make boost::optional<T> trivially destructible, copyable and movable if T
is
------------------------------+-------------------------------
 Reporter:  1zeeky@…          |      Owner:  Fernando Cacciola
     Type:  Feature Requests  |     Status:  new
Milestone:  To Be Determined  |  Component:  optional
  Version:                    |   Severity:  Not Applicable
 Keywords:                    |
------------------------------+-------------------------------
 Conceptually there's nothing preventing {{{boost::optional<T>}}} from
 being trivially destructible, copyable and movable if T is.
 This could be useful, for instance, to use an {{{boost::optional<T>}}} as
 a union-member.

 I have a POC implementation based on Boost 1.64
 [https://github.com/z33ky/trivial_optional/blob/master/optional.hpp here].
 \\
 I moved {{{m_storage}}} and {{{m_initialized}}} to a new {{{class
 optional_storage}}}, representing the new base class. Some methods
 managing those members are move there as well.
 {{{optional_base}}} indirectly inherits from {{{optional_storage}}}
 through {{{optional_destroyer}}}, {{{optional_mover}}} and
 {{{optional_copier}}}, which are templated classes including a boolean
 parameter to determine whether {{{T}}} is trivially destructible, movable
 and copyable and use template specialization to provide the respective
 trivial members. \\
 The implementation relies on defaulting constructors, so without C++11 or
 newer only trivial destruction is possible.

-- 
Ticket URL: <https://svn.boost.org/trac10/boost/ticket/13208>
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