Re: crashes during Feval from within WINDOW_WANTS_HEADER_LINE_P

[Nick Roberts]

I'm not an expert, but

 > I'm getting crashes after extending a macro.  I would appreciate your  
 > help.
 > 
 > I have added to the WINDOW_WANTS_HEADER_LINE_P macro (dispextern.h) a  
 > function call to an elisp function whose name is stored in `window- 
 > wants-header-line-function':
 > 
 >        && (NILP(Vwindow_wants_header_line_function)  
 > ||                   \
 >        !NILP (safe_call_win(Vwindow_wants_header_line_function, (W)))))
 > 
 > 
 > 
 > safe_call_win looks pretty straight-forward:
 > 
 > /* Call function FN with window argument.
 >     Return the result, or nil if something went wrong. */
 > 
 > Lisp_Object
 > safe_call_win (fn, w)
 >       Lisp_Object fn;
 >       struct window *w;
 > {
 >    Lisp_Object window;
 >    Lisp_Object val;
 >    struct gcpro gcpro1;
 >    val = Qnil;
 >    window = Qnil;
 >    if ((FUNCTIONP (fn)))
 >      {
 >        XSETWINDOW (window, w);

I don't think you need GCPRO1 here

 >        GCPRO1 (window);
 >        val = safe_call1 (fn, window);
 >        UNGCPRO;
 >      }
 >    return val;
 > }
 > 
 > However, I keep getting crashes, always during the evaluation of said  
 > function:

and it looks to me like the elisp function whose name is stored in
`window-wants-header-line-function' is a lisp primitive which either has
too many argumnts ( > 8 ) or whose argument list has been incorrectly
defined.

 > 5   libSystem.B.dylib                0x966639af abort + 73
 > 6   org.gnu.Emacs                    0x000f320b Feval + 923 (eval.c:2362)
 > 7   org.gnu.Emacs                    0x000f360f Fprogn + 63 (eval.c:450)
 > 8   org.gnu.Emacs                    0x000f38df funcall_lambda + 671  
 > (eval.c:3185)
 > 9   org.gnu.Emacs                    0x000f3c2b Ffuncall + 443 (eval.c: 
 > 3062)
 > 10  org.gnu.Emacs                    0x000f1f3a  
 > internal_condition_case_2 + 266 (eval.c:1583)
 > 11  org.gnu.Emacs                    0x0001717e safe_call + 158 (xdisp.c: 
 > 2348)
 > 12  org.gnu.Emacs                    0x000171c5 safe_call1 + 37 (xdisp.c: 
 > 2362)
 > 13  org.gnu.Emacs                    0x00017278 safe_call_win + 168  
 > (xdisp.c:2382)
 > 14  org.gnu.Emacs                    0x0016cc4b draw_fringe_bitmap_1 +  
 > 1467 (fringe.c:669)
 > 15  org.gnu.Emacs                    0x0016cf2a draw_fringe_bitmap + 90  
 > (fringe.c:868)
 > 
 > The elisp function that is called just evaluates to nil or t and  
 > doesn't do anything else. (It does work in some cases.)
 > The crashes do not depend on the `window' argument, and they do not go  
 > away if I play around with the GCPRO call or an additional BLOCK_INPUT.
 > 
 > What's going on? 

but I might have it wrong.

-- 
Nick                                           http://www.inet.net.nz/~nickrob