Re: stack overflow equal? values

[Kevin Ryde]

address@hidden (Ludovic Courtès) writes:
>
> I propose the following simple fix.  Ok to apply?

Yep, looks good.

After I posted I wondered if the values struct is an actual "s" or if
there's some strange extra I couldn't spot.  Testing eq avoids
worrying about that.

Dunno why values are a struct and not a smob cell.

> Actually, `scm_i_struct_equalp ()' should also compare the "tail
> elements" (when there are tail elements),

Yes.

> but their semantics are a
> little fuzzy to me.  In particular, I don't understand why the size of
> the tail array can be specified in both `make-vtable-vtable' and
> `make-struct': What does that mean?  Which one should really be taken
> into account?

Dunno :).

> It seems that the code is a bit unclear on this too:
>
>   guile> (define v (make-vtable-vtable "pr" 0))
>   guile> (define s (make-struct v 123))
>   guile> (struct-ref s 10)
>   Segmentation fault

A segv is a bug, obviously, whichever way it's actually meant to be.

> (Looks like the API is so complex that few people actually bothered to
> use it to its full extents.  ;-))

The records level is friendlier I guess.  For a long time I couldn't
understand what "vtable" meant, I still don't think I quite do.  Maybe
the docs should be tweaked, to help show what structs are typically
meant to be.

> --- orig/test-suite/tests/structs.test
> +++ mod/test-suite/tests/structs.test
> @@ -82,12 +82,18 @@
>         (set-owner! ball "Bill")
>         (string=? (owner ball) "Bill")))
>  
> -  (pass-if "equal?"

You can make a with-test-prefix group if you like.  An exercise of an
actual values too will be good, maybe in eval.test.