Re: MPS symbols

[Gerd Möllmann]

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Helmut Eller <eller.helmut@gmail.com> writes:
>
>> On Fri, Jun 28 2024, Gerd Möllmann wrote:
>>
>>> Gerd Möllmann <gerd.moellmann@gmail.com> writes:
>>>
>>>> Forgot something. While looking at the scanner, I wondered if we could
>>>> remove the is_mps check from fix_lisp_obj now that we have the dump
>>>> in MPS...
>>>
>>> Let's find out, pushed. Works for me :-)
>>
>> I think this uncovered a bug.  Now this
>>
>>   emacs -Q -eval '(progn (view-hello-file) (forward-line 7) (dotimes (_ 5)
>>   (redisplay) (igc--collect) (forward-line)))' -f kill-emacs
>>
>> causes a SIGSEGV in fix_font,
>>
>>       case FONT_OBJECT_MAX:
>>      {
>>        struct font *f = (struct font *)v;
>>        const Lisp_Object *type = &f->driver->type;
>>        IGC_FIX12_OBJ (ss, igc_const_cast (Lisp_Object *, type));
>>      }
>>
>> It turns out that f->driver is the variable xfont_driver and it is
>> actually const and the type field is a builtin symbol.  So it looks like
>> we can remove fix_font completely.
>
> Hm, okay. Can you see why is segfaults? I'm wondering because I'd have
> thought that we'd crash all over the place if we couldn't handle
> built-in symbols...

Please scratch that, I see it (macOS doesn't even have a definition for
struct font_driver...). I'll remove fix_font.