Re: problem with dynamic_cast

[Chris Faylor <cgf at cygnus dot com>]

This is a c++ problem.  You should probably report this to a c++ mailing list.
Check out http://sources.redhat.com/ for a list of available mailing lists.

cgf

On Thu, Sep 07, 2000 at 04:50:18PM +0100, Kris Thielemans wrote:
>Hi,
>
>I have a tiny bit more information on this problem.
>
>- I reproduced it on my own NT box, with cygwin 1.1.4 (it does NOT happen
>with B20.1)
>
>- I can reproduce it with a file (attached) that does not need linking with
>any other file (except standard libs).
>* If I do a normal "g++ dynamic_cast8.cxx", the program runs fine
>* If I link it with another file I have "g++ dynamic_cast8.cxx bla.o" it
>crashes.
>
>The other file is also compiled with the same gcc (it's not specific to
>which file exactly).
>
>
>Weird.
>
>Suggestions ?
>
>Kris
>
>
>> -----Original Message-----
>> From: Kris Thielemans [mailto:kris.thielemans@ic.ac.uk]
>> Sent: 31 August 2000 15:58
>> To: Gnuwin
>> Subject: problem with dynamic_cast
>>
>>
>> Hi,
>>
>> I have a problem with some of our own C++ software when compiled
>> with gcc on cygwin cygwin v.1.1.4 on Windows NT4.00.1381 (Finnish
>> language). Note that this program runs fine on my own NT 4.0 sp5
>> or sp6 machines running cygwin B20.1 with gcc 2.95.2, and on
>> Solaris with gcc 2.95.2, and on AIX with gcc 2.8.1).
>>
>> The problem occurs when executing a dynamic_cast on a pointer.
>> Any suggestions ?
>>
>>
>> details:
>> ---------
>> The program generates the following error:
>>    0 [main] test_VoxelsOnCartesianGrid 1039 handle_exceptions: Exception:
>> STATUS_ACCESS_VIOLATION
>>    974 [main] test_VoxelsOnCartesianGrid 1039 stackdump: Dumping
>> stack trace
>> to test_VoxelsOnCartesianGrid.exe.stackdump
>> make: *** [run_tests] Segmentation fault (core dumped)
>>
>> The file where it crashes is compiled as follows:
>> g++  -g -D_DEBUG -g  -Wall  -I/home/PPhead/include  -o
>> debug/VoxelsOnCartesianGrid.o -c VoxelsOnCartesianGrid.cxx
>>
>>
>> When running the program in gdb, the stack trace after the crash is:
>> Program received signal SIGSEGV, Segmentation fault.
>> 0x611e4 in ?? ()
>> (gdb) info stack
>> #0  0x611e4 in ?? ()
>> #1  0x41e484 in __si_type_info::dcast (this=0x460520, to=@0x4604c0,
>>     require_public=1, addr=0xa057e90, sub=0x460280, subptr=0xa057e90)
>>     at /cygnus/netrel/src/gcc-2.95.2-2/gcc/cp/tinfo.cc:76
>> #2  0x41e6d3 in __dynamic_cast (
>>     from=0x441658 <Tomo::ProjDataInfoCylindricalArcCorr type_info
>> function>,
>>     to=0x4415a4 <Tomo::ProjDataInfoCylindrical type_info function>,
>>     require_public=1, address=0xa057e90,
>>     sub=0x441544 <Tomo::ProjDataInfo type_info function>,
>> subptr=0xa057e90)
>>     at /cygnus/netrel/src/gcc-2.95.2-2/gcc/cp/tinfo2.cc:38
>> #3  0x40ddda in Tomo::find_sampling_and_z_size (z_sampling=@0x266f898,
>>     s_sampling=@0x266f894, z_size=@0x266f89c,
>> proj_data_info_ptr=0xa057e90)
>>     at VoxelsOnCartesianGrid.cxx:45
>> #4  0x4325e8 in
>> Tomo::VoxelsOnCartesianGrid<float>::VoxelsOnCartesianGrid (
>>     this=0x266fc00, proj_data_info=@0xa057e90, zoom=2.29999995,
>>     origin=@0x266fd10, make_xy_size_odd=false) at
>> VoxelsOnCartesianGrid.cxx:138
>> #5  0x4022a6 in Tomo::VoxelsOnCartesianGridTests::run_tests
>> (this=0x266fd60)
>>     at test_VoxelsOnCartesianGrid.cxx:103
>> #6  0x403174 in main () at test_VoxelsOnCartesianGrid.cxx:180
>> #7  0x61002272 in _size_of_stack_reserve__ ()
>> #8  0x61002805 in _size_of_stack_reserve__ ()
>> #9  0x61002843 in _size_of_stack_reserve__ ()
>> #10 0x41cdd5 in cygwin_crt0 ()
>>
>>
>> This seems to say there is something wrong in the dynamic_cast
>> statement on that line, which looks as follows:
>>   if (const ProjDataInfoCylindrical*
>>         proj_data_info_cyl_ptr =
>> 	dynamic_cast<const ProjDataInfoCylindrical*>(proj_data_info_ptr))
>>   { ...}
>>
>> By the way, if you check the stack trace, you'll see that the
>> dynamic cast is from a ProjDataInfoCylindricalArcCorr * to a
>> ProjDataInfoCylindrical *, where ProjDataInfoCylindricalArcCorr
>> is derived from ProjDataInfoCylindrical. (Not that it should
>> crash in any case).
>>
>>
>> Thanks !
>>
>>
>>
>> Kris Thielemans
>> (kris.thielemans@ic.ac.uk)
>> MRC Cyclotron Unit,
>> Hammersmith Hospital,
>> DuCane Rd,London W12 0NN, United Kingdom
>>
>> Phone on :   +44 (020)8383 3731
>> FAX on :     +44 (020)8383 2029
>>
>> NEW web site address:
>> http://www.cu.mrc.ac.uk/~kris


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