Re: [scratch/igc] 985247b6bee crash on Linux, KDE, Wayland

[Eval EXEC]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Eval EXEC <execvy@gmail.com>
>> Cc: pipcet@protonmail.com,  gerd.moellmann@gmail.com,  emacs-devel@gnu.org
>> Date: Fri, 06 Sep 2024 14:34:00 +0800
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> >> From: Eval EXEC <execvy@gmail.com>
>> >> Cc: pipcet@protonmail.com,  gerd.moellmann@gmail.com,  emacs-devel@gnu.org
>> >> Date: Fri, 06 Sep 2024 11:10:15 +0800
>> >> 
>> >> Eval EXEC <execvy@gmail.com> writes:
>> (gdb) frame 10
>> #10 0x00000000006919f8 in fix_cons (cons=0x7f08addd06b0, ss=0x7ffc7653e6f8) 
>> at /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/igc.c:1751
>> 1751        IGC_FIX12_OBJ (ss, &cons->u.s.car);
>> (gdb) p *cons
>> $3 = {
>>   gc_header = {
>>     v = 16630752781,
>>     gcaligned = 13 '\r'
>>   },
>>   u = {
>>     s = {
>>       car = XIL(0x7f0889546b70),
>>       u = {
>>         cdr = XIL(0x7f08936d87d3),
>>         chain = 0x7f08936d87d3
>>       }
>>     },
>>     gcaligned = 112 'p'
>>   }
>> }
>> (gdb) xcons
>> Invalid cast.
>
> Try these commands instead:
>
>  (gdb) p *cons
>  (gdb) p cons->u.s.car
>  (gdb) xtype
>  (gdb) xsymbol
>  (gdb) p cons->u.s.u.cdr
>  (gdb) xtype

It seems that execute `xcons` have valid output now, but execute `xcons`
twice, it will show "Invalid cast":
(gdb) frame 10
#10 0x00000000006919f8 in fix_cons (cons=0x7f08addd06b0, ss=0x7ffc7653e6f8) at 
/home/exec/Projects/git.savannah.gnu.org/git/emacs/src/igc.c:1751
1751        IGC_FIX12_OBJ (ss, &cons->u.s.car);
(gdb) p *cons
$1 = {
  gc_header = {
    v = 16630752781,
    gcaligned = 13 '\r'
  },
  u = {
    s = {
      car = XIL(0x7f0889546b70),
      u = {
        cdr = XIL(0x7f08936d87d3),
        chain = 0x7f08936d87d3
      }
    },
    gcaligned = 112 'p'
  }
}
(gdb) p *cons
$2 = {
  gc_header = {
    v = 16630752781,
    gcaligned = 13 '\r'
  },
  u = {
    s = {
      car = XIL(0x7f0889546b70),
      u = {
        cdr = XIL(0x7f08936d87d3),
        chain = 0x7f08936d87d3
      }
    },
    gcaligned = 112 'p'
  }
}
(gdb) p cons->u.s.car
$3 = XIL(0x7f0889546b70)
(gdb) xtype
Lisp_Symbol
(gdb) xsymbol
$4 = (struct Lisp_Symbol *) 0x7f088a262a50
Cannot access memory at address 0x4c78
(gdb) p cons->u.s.u.cdr
$5 = XIL(0x7f08936d87d3)
(gdb) xtype
Lisp_Cons
(gdb) xcons
$6 = (struct Lisp_Cons *) 0x7f08936d87d0
{
  gc_header = {
    v = 0x3df45270d,
    gcaligned = 0xd
  },
  u = {
    s = {
      car = XIL(0x38),
      u = {
        cdr = XIL(0),
        chain = 0x0
      }
    },
    gcaligned = 0x38
  }
}
(gdb) xcons
$7 = (struct Lisp_Cons *) 0x7f08936d87d0
{
  gc_header = {
    v = 0x3df45270d,
    gcaligned = 0xd
  },
  u = {
    s = {
      car = XIL(0x38),
      u = {
        cdr = XIL(0),
        chain = 0x0
      }
    },
    gcaligned = 0x38
  }
}
(gdb) p *cons
$8 = {
  gc_header = {
    v = 16630752781,
    gcaligned = 13 '\r'
  },
  u = {
    s = {
      car = XIL(0x7f0889546b70),
      u = {
        cdr = XIL(0x7f08936d87d3),
        chain = 0x7f08936d87d3
      }
    },
    gcaligned = 112 'p'
  }
}
(gdb) xcons
Invalid cast.

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