Re: [Boost-users] [Boost.Test] valgrind complains about invalid reads

Subject: Re: [Boost-users] [Boost.Test] valgrind complains about invalid reads
From: Peter Klotz (peter.klotz_at_[hidden])
Date: 2008-11-21 16:08:26

Gennadiy Rozental wrote:
> Peter Klotz wrote:
>> James Sutherland wrote:
>>> Try compiling a debug version.  That will give you line numbers to 
>>> help you track it down easier.
>>> James
>>
>> Found the problem. It was a non virtual destructor in class test_unit.
>>
>> Since test_unit is the base class of test_case, test_suite and 
>> master_test_suite_t it needs a virtual destructor.
> 
> No. It does not. We never delete test units through pointer to test_unit.
> 
>> In deregister_test_unit() a test_unit* pointer is passed which may 
>> actually point to a derived class. Calling delete without a virtual 
>> destructor leads to undefined behavior (and makes valgrind complain).
> 
> deregister_test_unit does not cause delete command. In fact it's being 
> call from destructor.

Please see the output of my simple example (with extra output in 
Boost.Test):

With virtual destructor in test_unit:

register_test_unit( test_case* tc )
tc=0x42c4ab0
register_test_unit( test_suite* ts )
ts=0x42c4ba8
Running 1 test case...

*** No errors detected
deregister_test_unit( test_unit* tu )
tu=0x42c4ba8
deregister_test_unit( test_unit* tu )
tu=0x42c4ab0

Here the pointers in register_test_unit()/deregister_test_unit() match 
as expected.

Without virtual destructor in test_unit:register_test_unit( test_case* tc )
register_test_unit( test_case* tc )
tc=0x42c4ab0
register_test_unit( test_suite* ts )
ts=0x42c4ba8
Running 1 test case...

*** No errors detected
deregister_test_unit( test_unit* tu )
tu=0x42c4bac
deregister_test_unit( test_unit* tu )
tu=0x42c4ab0

Here the test_unit pointer is not correct and does not match the one 
initially registered!

I agree that deregister_test_unit() does not delete the test_suite but 
the pointers ought to match.

Maybe you can run my simple test case using valgrind. I used version 
3.3.1 under Ubuntu 8.10 i386 (gcc 4.3.2) and Red Hat Enterprise Linux 5 
x86_64 (gcc 4.1.2).

Regards, Peter.