[Boost-bugs] [Boost C++ Libraries] #11670: Boost intrusive constructors should be constexpr

Subject: [Boost-bugs] [Boost C++ Libraries] #11670: Boost intrusive constructors should be constexpr
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-09-18 23:15:49

#11670: Boost intrusive constructors should be constexpr
------------------------------+------------------------
 Reporter:  ben.maurer@…      |      Owner:  igaztanaga
     Type:  Bugs              |     Status:  new
Milestone:  To Be Determined  |  Component:  intrusive
  Version:  Boost 1.60.0      |   Severity:  Problem
 Keywords:                    |
------------------------------+------------------------
 Boost intrusive constructors should be marked constexpr. Doing so would
 allow for their use in static variables without SIOF. As an example
 consider this program that uses a simple linked list

 http://ideone.com/O5YWM8


 because the LinkedList constructor is not constexpr, the variable gets
 initialized in file declaration order -- after my_crazy_variable.
 Therefore even though my_crazy_variable's ctor pushes something on to the
 list, it gets lost when the list is initialized and the program crashes
 due to being unable to pop a value.

 However, if you declare LinkedList's constructor constexpr the list is
 initialized in the zero initialization phase
 (http://en.cppreference.com/w/cpp/language/initialization#Non-

 local_variables). This means that the linked list can be used in other
 constructors without worrying about initialization order.

 While my example is obviously not a sane use case, imagine a linked list
 that registers all live Widget objects. if somebody creates a widget
 during static initialization they could encounter the same problem.

 A side benefit to doing this is that code size is reduced as the code to
 initialize the linked list is not created

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11670>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.