[lldb-dev] lldb crash while debugging wxWidgets application that was built with g++

Tue Apr 8 14:24:32 PDT 2014

In the meanwhile, here is the crash backtrace when it crashe ( the scenario
is: gdb is debugging lldb which debugs a debug version of codelite ;) )
http://pastebin.com/PVcZeQFk

HTH

On Wed, Apr 9, 2014 at 12:19 AM, Greg Clayton <gclayton at apple.com> wrote:

> You can check this yourself by searching for "wxClientDataContainer" in an
> command line LLDB session that has your debug symbols loaded for codelight:
>
> % lldb /path/to/codelight
> (lldb) image lookup --type wxClientDataContainer
>
> See if you see any complete definitions that are printed out. If so, then
> solution #1 will probably get around this issue for the moment. But we
> should still not crash even if we do look for a complete
> "wxClientDataContainer" definition and don't find one (also part of the fix
> for solution #1).
>
> Greg
>
> On Apr 8, 2014, at 2:16 PM, Eran Ifrah <eran.ifrah at gmail.com> wrote:
>
> >
> >
> >
> > On Wed, Apr 9, 2014 at 12:11 AM, Greg Clayton <gclayton at apple.com>
> wrote:
> > This is a serious problem with the debug info that GCC and Clang
> recently started to emit to try and save space by omitting important debug
> info.
> >
> > The problem is:
> >
> > class A : public B
> > {
> > }
> >
> > The debug info for "A" is complete, but since no one used stuff from
> class "B" they decided to just forward declare "B". Why is this a problem?
> Because we are trying to reconstruct a class definition of "A" using
> incomplete information.
> >
> > There are two things that can fix this:
> > 1 - Modify the DWARF parser to look for a complete version of "B"
> elsewhere in the current executable's debug info (but there might not be
> one).
> > 2 - Change flags to GCC to have it not elide this debug info (don't know
> what these flags would be, you will need to find out if there is such a
> flag).
> > 3 - Just start and complete the definition for "B" and pretend it is a
> class that contains nothing
> >
> > Solution #1 is might alleviate some of the problems, but often will
> result in a failure when there is no complete definition of "B".
> >
> > Solution #2 is the best solution, but this doesn't mean that people
> won't run into this crasher when debugging random code.
> >
> > Solution #3 is dangerous because you might have foo.cpp whose debug info
> has complete definitions for A and B, and bar.cpp that has a complete
> definition for A but not for B. Then you write and expression that uses an
> instance of "A" from foo.cpp and uses it with an instance of "A" from
> bar.cpp and the expression parser will now complain that is has two
> competing definitions for class "A" that don't match.
> >
> > Solution #1 should probably be tried first. If you can send me the
> executable you were debugging with debug info inside it, I can look and see
> if solution #1 will fix your current problem. We should avoid crashing,
> that is for sure.
> >
> > This  might be a slight problem since I was trying to debug codelite.
> > With debug symbols it can go up to 200MB and it consists of way too many
> shared libraries
> > Let me first to try and narrowing it to something minimalistic
> >
> >
> > Greg
> >
> > On Apr 8, 2014, at 1:49 PM, Eran Ifrah <eran.ifrah at gmail.com> wrote:
> >
> > > Hi,
> > >
> > > While debugging a real world application (codelite) I placed a
> breakpoint in the 'OnAbout' function
> > > attempting to view any of the local variables resulted in crash, see
> below:
> > >
> > > Process 24146 stopped
> > > * thread #1: tid = 24146, 0x00000000006667f6
> codelite`clMainFrame::OnAbout(this=0x000000000215f5c0,
> (null)=0x00007fffa6fd2640) + 66 at frame.cpp:1794, name = 'codelite', stop
> reason = step over
> > >     frame #0: 0x00000000006667f6
> codelite`clMainFrame::OnAbout(this=0x000000000215f5c0,
> (null)=0x00007fffa6fd2640) + 66 at frame.cpp:1794
> > >    1791     wxString mainTitle;
> > >    1792     mainTitle = CODELITE_VERSION_STR;
> > >    1793
> > > -> 1794     AboutDlg dlg(this, mainTitle);
> > >    1795     dlg.SetInfo(mainTitle);
> > >    1796     dlg.ShowModal();
> > >    1797 }
> > > (lldb) p dlg
> > > error: libwx_gtk2u_unofficial_core-3.0.so.0 DWARF DIE at 0x030ac4cc
> for class 'wxSizer' has a base class 'wxClientDataContainer' that is a
> forward declaration, not a complete definition.
> > > Please file a bug against the compiler and include the preprocessed
> output for
> /home/david/devel/packages/wx/3.0-2/wxwidgets3.0-3.0.0/objs_gtk_sh/../src/common/sizer.cpp
> > > Segmentation fault
> > >
> > > From the segfault message, I understand that this is a bug with gcc
> > > Still, is there a way to suppress this error by telling lldb to
> silently ignore this? ( I prefer it to display nothing instead of crashing
> and taking down codelite with it )
> > >
> > > Thanks
> > >
> > > --
> > > Eran Ifrah
> > > Author of codelite, a cross platform open source C/C++ IDE:
> http://www.codelite.org
> > > wxCrafter, a wxWidgets RAD: http://wxcrafter.codelite.org
> > > _______________________________________________
> > > lldb-dev mailing list
> > > lldb-dev at cs.uiuc.edu
> > > http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
> >
> >
> >
> >
> > --
> > Eran Ifrah
> > Author of codelite, a cross platform open source C/C++ IDE:
> http://www.codelite.org
> > wxCrafter, a wxWidgets RAD: http://wxcrafter.codelite.org
>
>

-- 
Eran Ifrah
Author of codelite, a cross platform open source C/C++ IDE:
http://www.codelite.org
wxCrafter, a wxWidgets RAD: http://wxcrafter.codelite.org
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