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Re: Fwd: failure notice


On Tue, Dec 8, 2015 at 1:57 PM, Tom Kacvinsky
<tom.kacvinsky@vectorcast.com> wrote:
> On Tue, Dec 8, 2015 at 11:55 AM, Tom Kacvinsky
> <tom.kacvinsky@vectorcast.com> wrote:
>> On Tue, Dec 8, 2015 at 11:49 AM, Jon Turney <jon.turney@dronecode.org.uk> wrote:
>>> On 07/12/2015 16:17, Tom Kacvinsky wrote:
>>>>
>>>> On Mon, Dec 7, 2015 at 10:24 AM, Tom Kacvinsky wrote:
>>>>>
>>>>> On Mon, Dec 7, 2015 at 10:19 AM, Jon Turney wrote:
>>>>>>
>>>>>> On 04/12/2015 14:20, Tom Kacvinsky wrote:
>>>>>>>
>>>>>>> We have an interesting problem whereby an Linux X client application
>>>>>>> crashes when running the X server on cygwin.  We have a reproducer
>>>>>>> for the problem, but it is a Qt example application stored in a
>>>>>>> tarball.
>>>>>>>
>>>>>>> We have gathered the other information that would typically be
>>>>>>> requested.
>>>>>>> I just need to know the best way of getting this information to the
>>>>>>> list.
>>>>>>
>>>>>>
>>>>>>
>>>>>> If the tarball is being rejected by the mailing list, I'd suggest you
>>>>>> upload
>>>>>> it to some file hosting site and send a link to the mailing list.
>>>>>>
>>>>>> If that is really not possible for you (why?), you may, on this specific
>>>>>> occasion only, mail it directly to me.
>>>>>
>>>>>
>>>>> Hi Jon,
>>>>>
>>>>> That is totally do-able.  I will get it on a hosting site and send the
>>>>> link.
>>>>
>>>>
>>>> Here is the DropBox link.
>>>>
>>>> https://www.dropbox.com/s/b6exaxm30j8q318/cygwin-x-repro.zip?dl=0
>>>
>>>
>>> Sorry, I hadn't noticed that you are describing a crash in the Qt client,
>>> not the Cygwin X server.
>>>
>>> So, firstly, this is a Qt issue.
>
> It could be, since you aren't able to reproduce with Qt 4.8.1, but we can
> with 4.8.5 that we built.  See below.
>
>>>
>>> It may well be that the multiwindow mode window manager for the Cygwin X
>>> server doesn't satisfy some expectation that Qt has (and I would be
>>> interested to know what that is), but Qt crashing is never the right
>>> thing to do.
>>>
>>> A backtrace of the Qt client when it crashes might be informative.
>>>
>>
>> Will attempt to get one.  I recall seeing in our internal bug tracking system
>> the exact X server error message.  Would that be of use?
>>
>
> There is no hard crash with a core dump so I can't get a backtrace.  The client
> dies with no diagnostics - the GUI goes away and we return to the command
> prompt.

While the application doesn't crash with a core dump even thought
assertion is triggered
(probably due to signal handlers installed by the Ada run time we
use), we do see this when
the application exits:

../../src/xcb_io.c:528: _XAllocID: Assertion `ret != inval_id' failed.

I don't know if this additional information is of use.

>
>>>> Please note it is a Qt reproducer.  We have some hard coded paths in
>>>> the Makefile that you will need to modify.  We are using Qt 4.8.6
>>>> built on Ubuntu 12.04, 32 bit.
>>>
>>> Nevertheless, I tried your reproducer in a Ubuntu 12.04 32-bit VM, but
>>> wasn't able to observe any crash.
>>>
>>> I note that an Ubuntu 12.04 only seems to have Qt 4.8.1.  Are you using a
>>> self-built Qt?
>>
>> Yes, we are using a self built Qt, pretty much a stock build, only thing we are
>> not doing is building the examples and demos.
>>
>
> We can provide the libraries we built and you can set LD_LIBRARY_PATH
> accordingly.
>

Do you want the libraries we have?  We have pinged Digia and they say
they won't look into this, especially considering Qt 4.8.x is EOL in
terms of support.

So, what are the next steps?

Thanks,

Tom

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