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

From: Eval Exec <[email-masked]>
Date: Thu, 13 Feb 2025 10:41:24 +0800

(gdb) source /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/.gdbinit
warning: /home/exec/Projects/git.savannah.gnu.org/git/../lwlib: No
such file or directory
SIGINT is used by the debugger.
Are you sure you want to change it? (y or n) [answered Y; input not
from terminal]
DISPLAY = :0
TERM = tmux-256color
Breakpoint 1 at 0x4868eb: file
/home/exec/Projects/git.savannah.gnu.org/git/emacs/src/emacs.c, line
425.
Breakpoint 2 at 0x5cdb90: file
/home/exec/Projects/git.savannah.gnu.org/git/emacs/src/xterm.c, line
27130.
(gdb) fr 15
#15 0x0000000000704bdc in Fprin1 (object=XIL(0x7f9cb1637290),
printcharfun=XIL(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.
778       print_finish (&pc);
(gdb) p object
$1 = XIL(0x7f9cb1637290)
(gdb) xtype
Lisp_Symbol

On Thu, Feb 13, 2025 at 1:35 AM Pip Cet <[email-masked]> wrote:
>
> "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
>