Re: Type-error in C code

[Jan Djärv]

An Atom is 32 bits.  make_number can't cover that range when long is 32 bits, 
so it is an unsafe thing to do.  Best is to revert and go back to using a string.

        Jan D.


Julien Danjou skrev 2010-11-12 15.21:
> On Fri, Nov 12 2010, Stefan Monnier wrote:
>
> > static void
> > set_wm_state (Lisp_Object frame, int add, Atom atom, Atom value)
> > {
> >    struct x_display_info *dpyinfo = FRAME_X_DISPLAY_INFO (XFRAME (frame));
> >
> >    x_send_client_event (frame, make_number (0), frame,
> >                         dpyinfo->Xatom_net_wm_state,
> >                         make_number (32),
> >                         /* 1 = add, 0 = remove */
> >                         Fcons
> >                         (make_number (add ? 1 : 0),
> >                          Fcons
> >                          (atom,
> >                           value != 0 ? value : Qnil)));
> > }
> >
> > The error is to put an "Atom" into a cons cell: those can only hold
> > Lisp_Objects.  The usual compilation flags won't catch the error because
> > both types are actually some kind of integer, but if you
> > compile --enable-use-lisp-union-type, the C compiler will
> > dutyfully burp.
>
> Good catch Stefan. I should use this flag to compile my code now.
>
> The fix should be easy I think, you just need to replace atom with
> make_number (atom).
>
> I can provide a patch is that handier.