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Report From: Delphi-BCB/Compiler/C++/Front End/Destructors [ Add a report in this area ]

Report #: 91256

Status: Closed

Failure to destruct member shared_ptr after an exception is thrown

Project: C++Builder

Build #: 15.0.3953.35171

Version: 15.1

Submitted By: Øystein Svinning

Report Type: Crash / Data loss / Total failure

Date Reported: 2/1/2011 5:26:09 AM

Severity: Serious / Highly visible problem

Last Updated: 3/20/2012 2:24:39 AM

Platform: All platforms

Internal Tracking #: 281763

Resolution: Retest (Resolution Comments)

Resolved in Build: : 16.0.4239.42776

Duplicate of: None

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Description

Class Bar has  a member that is a boost::shared_ptr for an object of class Foo. Foo has a defined constructor and destructor.

class Bar
{
  public:
    Bar(const boost::shared_ptr<Foo>& input)
      FooPtr(input) {}

  private:
    std::string s0;
    std::string s1;
    boost::shared_ptr<Foo> FooPtr;
};

If the following code is executed the shared count of ptr will be 2 inside the catch block, it should be reduced to 1. Consecuently the object Foo pointed to by ptr will not be destructed when ptr goes out of scope.

boost::shared_ptr<Foo> ptr(new Foo());

try
{
  Bar barObj(ptr);
  {
    Bar barObjLocal(ptr);
  }

  throw 1;
}
catch (int i)
{
  // use_count of ptr is 2
}

Steps to Reproduce:

#include <iostream>
#include <boost/shared_ptr.hpp>

// Class with no contents. Constructor and destructor provide output to cout
class Foo
{
  public:
    Foo()
    {
      std::cout << "Constructing Foo" << std::endl;
    }
    ~Foo()
    {
      std::cout << "Destructing Foo" << std::endl;
    }
};
//---------------------------------------------------------------------------

// Class containing two strings and a pointer to a Foo object. Constructor sets
// the member Foo pointer. Destructor is not implemented.
class Bar
{
  public:
    Bar(const boost::shared_ptr<Foo>& input) : FooPtr(input) {}
//    ~Bar() {}

  private:
    std::string s0;
    std::string s1;
    boost::shared_ptr<Foo> FooPtr;
};
//---------------------------------------------------------------------------

int main(int argc, const char* argv[])
{
  boost::shared_ptr<Foo> ptr(new Foo());

  try
  {
    Bar barObj(ptr);
    {
      Bar barObjLocal(ptr);
    }

    throw 1;
  }
  catch (int i)
  {
    std::cout << "use_count for ptr in catch: " << ptr.use_count()
              << ", should be 1" << std::endl;
  }

  return 0;
}
//---------------------------------------------------------------------------

Workarounds

* Add an empty destructor to the class Bar in the example.
* Move FooPtr member of class Bar to the top of the list of private members in class Bar
* Do not put barObjLocal in a seperate scope inside the try block

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