[Bug c++/14388] New: wrong error msg when printing deferenced this pointer.

[Bug c++/14388] New: wrong error msg when printing deferenced this pointer.

[yanliu at ca dot ibm dot com]

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using ddd debuger to debug the executable file, a breakpoint is set on 
most_derived::method(). When program stops at the breakpoint, typing p *this,
the ddd debugger print out the following error message:

GNU DDD 3.3.1 (powerpc-suse-linux), by Dorothea Lütkehaus and Andreas Zeller.
Copyright © 1995-1999 Technische Universität Braunschweig, Germany.
Copyright © 1999-2001 Universität Passau, Germany.
(gdb) break t1.C:68
Breakpoint 1 at 0x10001740: file t1.C, line 68.
(gdb) run

Breakpoint 1, most_derived::method() (this=0x10011dbc) at t1.C:68
(gdb) p *this
$1 = {<left_class> = {Expected a negative vbase offset (old compiler?)

But when printing the dereference of this pointer address, which I think is the 
same as print *this, it doesn't give any error msg:

(gdb) p *(0x10011dbc)
$3 = 268441408

Using ddd debugging the same excetible compiled with g++ 3.2.2, I got a 
different error msg:
Breakpoint 1, most_derived::method() (this=0x10000c34) at t1.C:68
(gdb) p *this
can't find linker symbol for virtual table for `most_derived' value


Please verify whether this error msg is valid, and explain the meaning of this 
error msg.

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           Summary: wrong error msg when printing deferenced this pointer.
           Product: gcc
           Version: 3.2.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: yanliu at ca dot ibm dot com
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14388

[Bug c++/14388] wrong error msg when printing deferenced this pointer.

[yanliu at ca dot ibm dot com]

------- Additional Comments From yanliu at ca dot ibm dot com  2004-03-02 19:28 -------
Created an attachment (id=5844)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=5844&action=view)
testcase

The testcase is running on linux-ppc 2.4.21-111-pseries64 #1 SMP Thu Oct 30
23:57:04 UTC 2003 ppc.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14388

[Bug debug/14388] wrong error msg when printing deferenced this pointer.

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-03-02 19:39 -------
This works for me on x86-linux. Unfortunately, you don't say how you 
compiled your executable, and don't provide the exact output of gcc -v. 
Also note that 3.2.2 is no longer maintained, could you try with  
gcc 3.3.3? 
 
Thanks 
  Wolfgang 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
          Component|c++                         |debug


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14388

[Bug debug/14388] wrong error msg when printing deferenced this pointer.

[yanliu at ca dot ibm dot com]

------- Additional Comments From yanliu at ca dot ibm dot com  2004-03-02 19:47 -------
Here is the command that I am using:
xlCb -g t1.C
ddd a.out

THis is what I got using the gcc -v :
Reading specs from /usr/lib/gcc-lib/powerpc-suse-linux/3.2.2/specs
Configured with: ../configure --enable-threads=posix --prefix=/usr --with-local-
prefix=/usr/local --infodir=/usr/share/info --mandir=/usr/share/man --
libdir=/usr/lib --enable-languages=c,c++,f77,objc,java,ada --enable-libgcj --
with-gxx-include-dir=/usr/include/g++ --with-slibdir=/lib --with-system-zlib --
enable-shared --enable-__cxa_atexit powerpc-suse-linux
Thread model: posix
gcc version 3.2.2

I don't have gcc version 3.3 at hand, so cannot run the tc now.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14388

[Bug debug/14388] wrong error msg when printing deferenced this pointer.

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-03-02 20:29 -------
The other is that this might not be a GCC bug but rather a gdb bug which should be reported to them.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14388

[Bug debug/14388] wrong error msg when printing deferenced this pointer.

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-03-02 22:53 -------
Right, I forgot to ask that: what is the version of the debugger? ddd 
is only a fancy frontend, but it works on top of gdb or some other 
debugger. You should tell us which debugger and which version. 
 
W. 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14388

[Bug debug/14388] wrong error msg when printing deferenced this pointer.

[yanliu at ca dot ibm dot com]

------- Additional Comments From yanliu at ca dot ibm dot com  2004-03-03 16:11 -------
you are right, I should report this bug to GDB. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14388