[Insight-developers] ExceptionObject assignment crash on MSVC

[Luis Ibanez]

Hi Niels,


Removing the lines from the test may not be the right way to
address the problem. That will just give us a deceptively
green Dashboard and a false sense of security.


The memory leak reported for std::exception shouldn't result
in a crash, isn't it? ... it should just ... leak memory.



It may also be that the lines:


  ExceptionObject &
  ExceptionObject::operator= ( const ExceptionObject &orig )
  {
   // Assign its superclass:
   static_cast<Superclass &>(*this) = orig;



are entering in an infinite loop calling itself (recursion).
(e.g.the operator= may have been declared virtual in
std::exception. This will make the program crash
when the calling stack overflows.


I'll try running this in Debug mode...


   Luis


--------------------
Niels Dekker wrote:
> Bill Lorensen wrote:
> 
>> itkExceptionObjectTest is now failing on some platforms:
>> http://www.cdash.org/CDash/testSummary.php?project=2&name=itkExceptionObjectTest&date=20080530 
>>
> 
> 
> The failure of camelot.kitware (Linux-g++-4.3 20080530-0100-Nightly) 
> looks irrelevant, because that build failed on 1327 other tests as well. 
> http://www.cdash.org/CDash/viewTest.php?buildid=87527
> 
> OTOH, the failures on MSVC 6 and MSVC 7.1 builds look rather serious. 
> Fortunately I'm able to reproduce the crash locally, on MSVC 7.1.  In 
> itkExceptionObjectTest (itkExceptionObjectTest.cxx):
> 
>  E = F = G;
>  std::cout << F << std::endl;  // CRASH!
> 
> The assignment has somehow corrupted F.  I implemented the assignment of 
> ExceptionObject as follows:
> 
> ExceptionObject &
> ExceptionObject::operator= ( const ExceptionObject &orig )
> {
>  // Assign its superclass:
>  static_cast<Superclass &>(*this) = orig;
> 
>  // Assigns its smart pointer:
>  m_ExceptionData = orig.m_ExceptionData;
>  return *this;
> }
> 
> The first part calls the assignment operator of the superclass, i.e. 
> std::exception.  Which seemed to me like The Right Way To Do.  But I 
> didn't know that MSVC's std::exception-assignment has a bug: "Memory 
> leak on std::exception assignment operator"
> https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=328570 
> 
> 
> Luis, if you have time, please feel free to remove those two lines of 
> code from itkExceptionObjectTest.cxx:
> 
>  // Assign its superclass:
>  static_cast<Superclass &>(*this) = orig;
> 
> It appears to solve the crash instantly  :-)  I'm not 100 percent sure 
> about the cause of the crash, but it very much looks like it's caused by 
> std::exception's assignment.  Unfortunately I don't get it properly 
> tested anymore today. Otherwise it has to wait until tomorrow...
> 
> 
> Kind regards,
> 
>  Niels
>