Subject: Re: bug#75710: 31.0.50; feature/igc: crash report on Arch Linux, 2025-01-20

From: Pip Cet <[email-masked]>
Date: Wed, 22 Jan 2025 21:09:58 +0000

"Oliver Reiter" <[email-masked]> writes:

> Pip Cet <[email-masked]> writes:
>
>> While unsatisfying, my very preliminary conclusion is that there is a
>> significant chance that this is bug#75754.  My plan is to fix this bug
>> unconditionally (without #ifdef HAVE_MPS) on feature/igc because I
>> believe the bug is present, albeit much less likely, on master, and the
>> ultimate fix for bug#75754 is likely to be both very different and take
>> some time.
>>
>> Objections to this?
>
> If you are asking me: no objections.

A preliminary workaround for bug#75754 has been installed on
feature/igc, erring on the side of protecting too many objects rather
than too few of them.

I would ask you to please try the current branch, and to report any
further crashes you may see as a new bug; I may be wrong about all your
crashes being due to this bug, but maybe I'm right about one of them :-)

Thanks for the reports, again!

If you don't see a crash, can you let us know (without a new bug,
ideally) in a few days, and then we can mark these as probably closed?

Thanks!

>>> In GNU Emacs 31.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version
>>>  3.24.43, cairo version 1.18.2) of 2025-01-20 built on wilap
>>> Repository revision: 35437854166f8d0c1deceb7aba50f27cc838b490
>>> Repository branch: feature/igc
>>> System Description: Arch Linux
>>>
>>> Configured using:
>>>  'configure 'CFLAGS=-g3 -ggdb -Og -fno-omit-frame-pointer'
>>                                 ^^^
>>
>> I confess I rarely build with -Og: I'm in the -O0 team, or -Os just to
>> see some different compiler warnings once in a while.  Thanks for
>> testing with this flag; it might mean you see bugs others don't.
>>
>> In particular, stack marking with -O0 behaves in a more obvious fashion
>> than in optimized builds; while the intention of -Og is to keep
>> variables in the right location for debugging, I don't know how good GCC
>> is at doing that in practice.
>
> Thanks for the insight, I'll build with -O0 next time.

I wasn't trying to get you to do that.  Not going to stop you either, of
course.  All options need to be tested; we just need to find the right
balance between expanding our tests to find all possible crashes and
gathering data on the stability and usability of IGC by running a few
common builds and hoping they don't crash all the time.

Pip