Re: [Vala] workaround for assignment from incompatible pointer type

[James Moschou <james moschou gmail com>]

On 11 July 2010 03:58, Jan Hudec <bulb ucw cz> wrote:
> On Sat, Jul 10, 2010 at 02:29:16 +0000, James Moschou wrote:
> > Hello,
> >
> > I'm trying to subclass Clutter.Actor, I have:
> >
> > public override void allocate (ActorBox box, AllocationFlags flags) {...
> >
> > which generates:
> >
> > static void text_view_real_allocate (ClutterActor* base, ClutterActorBox* box,
> > ClutterAllocationFlags flags) {...
> >
> > However at the line where this gets assigned to the class pointer, it has the
> > error: "warning: assignment from incompatible pointer type".
>
> That would be a bug. When vala accepts to compile something, it should not
> generate these warnings.
>
> > I think because the class pointer is expecting a "const" in front of
> > "ClutterActorBox *box".
>
> No. Const can be added by assignment without any warnings. It can't be
> removed, but the error would be different.
>
> It's more likely the use of pointer to base vs. pointer to derived (since
> C does not have inheritance, they are incompatible pointers for C compiler).
>
> Can you please provide a simple test case where the problem appears? Report
> a bug in bugzilla and attach the test there, please.
>
> > Is this known?
>
> There appeared many cases where this warning was generated in the past. Some
> of them were fixed, some may have not been. Check the bugzilla whether you'll
> see similar-looking bug there. If yes, just add your test case, if no, open
> new bug.
>
> > Is there a workaround?
>
> You are not supposed to look at anything from the C compiler unless you are
> binding C library for vala (writing a .vapi). So as long as it otherwise
> works, disable C compiler warnings (you can tell valac to pass appropriate
> options with '-X' (so e.g. '-X -w').
>
> --
>                                                 Jan 'Bulb' Hudec <bulb ucw cz>


Here's the bug
https://bugzilla.gnome.org/show_bug.cgi?id=624139