R devel - Mar 2007 - Invalidating inaccessible SEXP?

Is there a (C or R) function to invalidate the relevant parts of SEXP
/ data that are inaccessible? My problem is in tracking down
protection and other memory mismanagement bugs, where I have to rely
on luck to invalidate or overwrite data to trigger a detectable
error. This makes it hard to track down a bug (it sometimes doesn't
occur), or to know that a patch fixes the problem.

Thanks,

Martin
-- 
Martin Morgan
Bioconductor / Computational Biology
http://bioconductor.org

On Fri, 16 Mar 2007, Martin Morgan wrote:
> Is there a (C or R) function to invalidate the relevant parts of SEXP
> / data that are inaccessible? My problem is in tracking down
> protection and other memory mismanagement bugs, where I have to rely
> on luck to invalidate or overwrite data to trigger a detectable
> error. This makes it hard to track down a bug (it sometimes doesn't
> occur), or to know that a patch fixes the problem.
>
Under Valgrind when R is compiled  --with-valgrind-instrumentation=2 the 
code walks the list of newly freed SEXPs and marks them as inaccessible 
(which is one reason why it is so slow).

I don't know of any other facilities to do what you want.

 	-thomas