Re: [Boost-bugs] [Boost C++ Libraries] #2359: Static initialization problems with fast_pool_allocator

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #2359: Static initialization problems with fast_pool_allocator
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-09-22 21:06:58

#2359: Static initialization problems with fast_pool_allocator
---------------------------+------------------------------------------------
  Reporter:  cnewbold      |       Owner:  cnewbold
      Type:  Bugs          |      Status:  new     
 Milestone:  Boost 1.37.0  |   Component:  pool    
   Version:  Boost 1.36.0  |    Severity:  Problem 
Resolution:                |    Keywords:          
---------------------------+------------------------------------------------

Comment(by cnewbold):

 Ah! This is just the sort of explanation I was looking for, but could not
 find--I guess my copy of the C++ standard has gone stale.

 Based on this, it certainly would appear that GCC's behavior is conformant
 and that the combination of fast_pool_allocator and singleton_default
 presumes behavior which is unspecified.

 My only concern is whether referencing singleton_default from the
 constructor for fast_pool_singleton will guarantee proper initialization
 ordering.

 3.6.2 doesn't really shed any light on how ordered and unordered
 initialization may be coupled. There isn't, for example, any expressed
 guarantee that non-locals will be initialized prior to first reference.

 == More from Joaquín: ==

 There is no such guarantee indeed, but the fix does NOT rely on
 initialization rules for non-local objects, but on the initialization
 rules for *local* objects with static storage duration (6.7/4): the
 singleton is a local static object inside the function
 singleton_default<T>::instance(), which is explicitly invoked inside
 fast_pool_allocator ctors via singleton_pool<...>is_from() (if you apply
 the fix, that is).

 The non-local object involved in singleton_default<T>, namely
 singleton_default<T>::create_object is there to guarantee that
 singleton_default<T>::instance() is invoked, and thus the singleton
 created in dynamic initialization time *if no one has done it before*.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/2359#comment:2>
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