[Libreoffice] crash in escherex.cxx in master

[Markus Mohrhard]

Ok I looked into the corresponding gcc stl function and it seems that the
debug function checks if the iterator is incrementable. I haven't checked
the macro that performs this check but the iterator might be marked as
invalid after an element has been erased. So this crash will only happen
during a debug build, but I think it is good to know that during a debug
build some additional checks are performed.

the relevant code is:

      _Safe_iterator&
      operator++()
      {
    _GLIBCXX_DEBUG_VERIFY(this->_M_incrementable(),
                  _M_message(__msg_bad_inc)
                  ._M_iterator(*this, "this"));
    ++_M_current;
    return *this;
      }

I still don't understand why it fails with my patch but this might be
because it is not delivered correctly. I'll push a patch based on your idea
to master.

2011/6/21 Noel Power <nopower at novell.com>

> On 21/06/11 18:52, Markus Mohrhard wrote:
>
>> I did a debug build. And I had some stl debug symbols in my backtrace so
>> it might be that perhaps the compiler won't optimize this out.
>>
>> I attached the backtrace.
>>
>> print it shows: it = {<__gnu_debug::_Safe_iterator_**base> = {_M_sequence
>> = 0x29e3678, _M_version = 0, _M_prior = 0x0, _M_next = 0x0}, _M_current =
>> {_M_current = 0x2a27bf0}}
>>
> ah, ok -D_GLIBCXX_DEBUG is enabled, right I tried to build some stuff
> partially ( with some extra debug flags etc. ) <sigh> didn't work ( link
> problems ) I will try a full debug build ( have never done that up to now )
>
> Noel
>
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