Re: [Boost-bugs] [Boost C++ Libraries] #3950: boost::interprocess::mapped_region destructor deletes shm where it shouldn't.

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3950: boost::interprocess::mapped_region destructor deletes shm where it shouldn't.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-05-23 07:51:50

#3950: boost::interprocess::mapped_region destructor deletes shm where it
shouldn't.
-------------------------------------------+--------------------------------
 Reporter:  Lénaïc Huard <lhuard@…>        |       Owner:  igaztanaga  
     Type:  Bugs                           |      Status:  new         
Milestone:  Boost 1.43.0                   |   Component:  interprocess
  Version:  Boost 1.42.0                   |    Severity:  Problem     
 Keywords:                                 |  
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Comment(by igaztanaga):

 I think GCC is right, because the dynamic type of the object is not rv<T>
 but T. We don't create any rv<T> object so downcasting T to a non-existent
 rv<T> object is at least doubtful. The standard says:

 INCITS+ISO+IEC+14882-2003
 C++03 standard.

 3.10 Lvalues and rvalues / 15

 If a program attempts to access the stored value of an object through an
 lvalue of other than one of the following types the behavior is
 undefined48):

 - the dynamic type of the object,
 - a cv-qualified version of the dynamic type of the object,
 - a type that is the signed or unsigned type corresponding to the
 dynamic type of the object,
 - a type that is the signed or unsigned type corresponding to a cv-
 qualified version of the dynamic type of
 the object,
 - an aggregate or union type that includes one of the aforementioned
 types among its members (including,
 recursively, a member of a subaggregate or contained union),
 - a type that is a (possibly cv-qualified) base class type of the
 dynamic type of the object,
 - a char or unsigned char type.

 rv<T> is a class, but not an aggregate class, since (8.5.1 Aggregates
 [dcl.init.aggr] p.2):

 An aggregate class is a class with no user-declared constructors, no
 private or protected non-static data members, no base classes, and no
 virtual functions.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3950#comment:9>
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