[Rd] Re: [R] Error message during debug (PR#6804)

[dmurdoch at pair.com]

On Tue, 20 Apr 2004 13:48:43 -0400 (EDT), "Gabor Grothendieck"
<ggrothendieck at myway.com> wrote :

>
>In R 1.9.0 on Windows XP Pro I get an error if I try to
>debug the identity function f shown:
>
> > f <- function(x)x
> > debug(f)
> > f(1)
> debugging in: f(1)
> Error in f(1) : Unimplemented feature in eval
> > R.version.string
> [1] "R version 1.9.0, 2004-04-12"
>
>Without debuggging its ok.

Confirmed.  It's not new in 1.9.0, it appears in 1.8.1 as well.  It
seems that a function body consisting of a single token triggers it.
I get a crash from this variation:

f <- function(x) 4

Maybe the system is trying to tell us that functions this simple don't
need debugging? ;-)

I'm sending this message to r-bugs to get it into the bug list (but I
won't have time to look at it until at least the weekend, if someone
else wants to fix it).

Duncan Murdoch