Subject: Re: bug#76218: [feature/igc] aa915b0c87e crash on Wayland/Linux Kde

From: Pip Cet <[email-masked]>
Date: Wed, 12 Feb 2025 17:35:34 +0000

"Eli Zaretskii" <[email-masked]> writes:

>> From: Eval Exec <[email-masked]>
>> Date: Wed, 12 Feb 2025 22:08:34 +0800
>> Cc: [email-masked]
>>
>> It's not latest igc branch, it
>> aa915b0c87e42444ee5426744df18c3b15ac0cf5 on Feb 6, 2025

That is older than the fixes for bugs which look very much like this
one.  My assumption is it's more efficient to attempt to reproduce the
bug with the current feature/igc branch; if we can't, it may have been
fixed, if we can, the backtrace may be more useful.

Thank you for the report, though! It's good to know that the fixes
appear to have some of the expected effect, and it's never a waste of
time to understand even a fixed bug better.

>> (gdb) fr 15
>> #15 0x0000000000704bdc in Fprin1 (object=0x7f9cb1637290,
>> printcharfun=0x7f9c747cd1ad, overrides=<optimized out>) at
>> /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/print.c:778
>> warning: Source file is more recent than executable.

That warning is usually very bad news, IME, because it means the source
code no longer corresponds to the binary we're using.

>> 778       print_finish (&pc);
>> (gdb) p object
>> $1 = (Lisp_Object) 0x7f9cb1637290
>> (gdb) xtype
>> Undefined command: "xtype".  Try "help".
>> (gdb)
>
> Do this:
>
>   (gdb) source /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/.gdbinit
>
> and then repeat the above commands.
>
> (The "xtype" command is defined in src/.gdbinit.)

The xtype will indicate this is a lisp symbol, as its tag bits are 0.
It doesn't seem to be a built-in symbol, and it looks unusual because of
the unusual settings used by Nix (OS?) which put static data (lispsym,
in this case) near the beginning of the address space rather than at
around 0x555555550000.

Pip