Re: [Cppunit-devel] Final answer: Exception::operator =() bug with VC++ (was :Partial answer: 2.3) Why does...)

[Baptiste L. <bl...@cl...>]

Went one step further in that quest...

When the std::exception::operator =() call the destructor and the
constructor to do the 'copy', the constructor reset the virtual table back
to std::exception
virtual table. Therefore, the previous affectation to CppUnit::Exception
virtual table is lost, and all call to any virtual function of
std::exception (what() is among them) will lead to a call to the
std::exception implementatin instead of the most derived class
implementation.

I beleive this is a MSVC++ STL bug (I'll tell you, that stuff is pure black
magic ;-) ). Has anyone heard of it ?

Well, anyway I'll go for the simplest thing that could possibly work and
comment out the call to std::exception::operator =() in
CppUnit::Exception::operator =() (no data from the base class are use
anyway). But at least, now we know what is going wrong !

And we finaly got to see the green bar =)

Thanks Phil,
Baptiste.

----- Original Message -----
From: "Phil Taylor" <phi...@ts...>
To: <cpp...@li...>
Sent: Thursday, October 04, 2001 2:57 PM
Subject: [Cppunit-devel] Partial answer: 2.3) Why does the test
ExceptionTest.testAssignment failed in CppUnit test


> The implementation of the assignment operator for std::exception in
> MSVCRT seems to be cause of the problem. Comment out the
> SuperClass::operator= (other) call in Exception::operator=(Exception&)
> and the test now passes.
>
> Examination of MSVCRT disassembly yields some odd-looking (shortcut?)
> behavior. It looks as though exception::operator=(exception&) resets
> itself by calling its own destructor (memory is not freed) then calls
> exception(exception&) to complete the assignment.
>
> I can't progress the problem any further at this time but the
> information above may be of some assistance.
>
> Regards,
> Phil
>
>
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