non-recursive recursive module segfault

non-recursive recursive module segfault

[Jeremy Yallop]

What behaviour should I expect for the following code? :

   module rec M :
   sig
     val m : unit -> unit
   end
     =
   struct
     let h _ _ = ()
     let m = h ()
   end

   let _ = M.m ()

According to the documentation this could trigger the exception 
"Undefined_recursive_module", but instead it segfaults.  If I remove the 
`rec' keyword then it "works", i.e. simply returns unit.

I was rather hoping that M would be treated as a non-recursive module, 
despite the `rec', since it's not actually recursive.  It's easy enough 
to avoid the segmentation fault: eta-expanding m, adding a trivial value 
component to the signature, removing `rec', etc., but I was hoping the 
compiler would help out in this case.

In any case, should the segmentation fault be considered a bug?

This is on OCaml 3.09.2/Linux/x86.

Jeremy.

Re: [Caml-list] non-recursive recursive module segfault

[Alain Frisch]

Jeremy Yallop wrote:
> What behaviour should I expect for the following code? :
> 
>   module rec M :
>   sig
>     val m : unit -> unit
>   end
>     =
>   struct
>     let h _ _ = ()
>     let m = h ()
>   end
> 
>   let _ = M.m ()
> 
> According to the documentation this could trigger the exception
> "Undefined_recursive_module", but instead it segfaults.

That's probably the bug 4008:

http://caml.inria.fr/mantis/view.php?id=4008

which is fixed in the 3.09 CVS branch (but not in the 3.10 branch, in
case you tried).

To get rid of the problem, you can either:

- use the CVS version (release309 branch);

- download, compile and link with the following files:

http://camlcvs.inria.fr/cgi-bin/cvsweb.cgi/~checkout~/ocaml/stdlib/camlinternalMod.mli?rev=1.1.8.2
http://camlcvs.inria.fr/cgi-bin/cvsweb.cgi/~checkout~/ocaml/stdlib/camlinternalMod.ml?rev=1.4.2.1

- use ocamlopt


-- Alain

Re: [Caml-list] non-recursive recursive module segfault

[Jeremy Yallop]

Alain Frisch wrote:
> Jeremy Yallop wrote:
>> What behaviour should I expect for the following code? :
[...]
> 
> That's probably the bug 4008:
> 
> http://caml.inria.fr/mantis/view.php?id=4008
> 
> which is fixed in the 3.09 CVS branch (but not in the 3.10 branch, in
> case you tried).
> 
> To get rid of the problem, you can either:
> 
> - use the CVS version (release309 branch);
> 
> - download, compile and link with the following files:
> 
> http://camlcvs.inria.fr/cgi-bin/cvsweb.cgi/~checkout~/ocaml/stdlib/camlinternalMod.mli?rev=1.1.8.2
> http://camlcvs.inria.fr/cgi-bin/cvsweb.cgi/~checkout~/ocaml/stdlib/camlinternalMod.ml?rev=1.4.2.1
> 
> - use ocamlopt

Thanks!  All of the above fixed the problem.  I'd looked on mantis to 
see if was a known problem, but bug 4008 didn't show up when I searched 
for "recursive module" (for obvious reasons).

Jeremy.