Hi Lubos
On 25/03/11 18:52, Lubos Lunak wrote:
On Friday 25 of March 2011, Noel Power wrote:
Ewww ...
class SAL_DLLPUBLIC_EXPORT IFieldmark
: virtual public IMark
...
class SAL_DLLPUBLIC_EXPORT ICheckboxFieldmark
: virtual public IFieldmark
...
IFieldmark* pFieldmark = ...
...
ICheckboxFieldmark* pCheckboxFm =
reinterpret_cast<ICheckboxFieldmark*>(pFieldmark);
You really don't want to reinterpret_cast up and down virtual inheritance.
undoubtedly ( and I was uneasy about it ) but... before posting the
patch I did check with valgrind and also printing out the result of the
pointers from the reinterpret_cast vrs the dynamic_cast ( on both the
working 64 & 32 builds ) and then valgrind again on the problematic
32bit ( with hack applied )
Does your changing from dynamic_cast to reinterpret_cast actually really fix
it? Since both the classes are defined in the same place, the only reasonable
explanation I see for this is that somebody got the casting similarly wrong
in another place and doing it wrong here too "undoes" the first wrong. I
don't have a very good explanation why this would be different for 32/64bit
though.
its worse as it's not just a 32bit vrs 64bit issue, its just the distro
( patches applied ) 32 that fails, all other distro/no-distro 32/64bit
combos work :-/
I don't have any 32bit build, could you try with yourself few more things?
First, using Valgrind is always a good idea,
absolutely ( and I did that before even posting here )
and second, the output of
something like this could be interesting too:
printf( "%p %p %s %p %p %s %p %p %s\n", ptr, dynamic_cast< void*>( ptr ),
typeid( *ptr ).name(), pFieldmark, dynamic_cast< void*>( pFieldmark ),
typeid( *pFieldmark ).name(), pCheckboxFm, dynamic_cast< void*>(
pCheckboxFm ), typeid( *pCheckboxFm ).name());
(where 'ptr' is what you get from the pMarksAccess->makeNoTextFieldBookmark()
call before casting to anything).
I'll check that later ( I didn't know about the typeid method ) so
thats a nice hint. Hmm I was concentrating so much on the circumstances
of the problem I missed a safer fix, the dynamic_cast/reinterpret_cast
is not really necessary it's more a convenience ( to be able to call the
Set/IsChecked methods ) but these methods themselves only call
IFieldmark related (pure) virtual methods and no ICheckboxmark related
functions ( which might someway explain why the hack works without
memory foobar )
Still I think there is something strange happening here, I would suspect
that you are halfway right and there is maybe somewhere a fundamental
error that we get away with somehow in all cases except the distro 32
bit. But really I admit I have no clue yet. I post the results of the
debug later when I get a chance, maybe it might throw some light
thanks again
Noel
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