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