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From: "Kris Thielemans" <kris DOT thielemans AT ic DOT ac DOT uk>
To: "Gnuwin" <cygwin AT sourceware DOT cygnus DOT com>
Subject: problem with dynamic_cast
Date: Thu, 31 Aug 2000 15:57:58 +0100
Message-ID: <005b01c0135b$da066de0$460a10ac@petnt1.rpms.ac.uk>
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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 DOT thielemans AT ic DOT ac DOT 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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