[External] Re: R-devel internal errors during check produce?

No packages are being loaded, or even installed.
Did you try running the example on R-devel built with flags I have
provided in this email?
I checked now and it is required to use --enable-strict-barrier to
reproduce the issue.

On Tue, Jun 30, 2020 at 9:02 AM Martin Maechler
<maechler at stat.math.ethz.ch> wrote:

Kurt Hornik
    on Tue, 30 Jun 2020 06:20:57 +0200 writes:

Jan Gorecki writes:

   >> Thank you both, You are absolutely correct that example
   >> should be minimal, so here it is.

   >> l = list(a=new.env(), b=new.env()) unique(l)

   >> Just for completeness, env_list during check that raises
   >> error

   >> env_list <- list(baseenv(),
   >>   as.environment("package:graphics"),
   >>   as.environment("package:stats"),
   >>   as.environment("package:utils"),
   >>   as.environment("package:methods") )

   >> unique(env_list)

   > Thanks ... but the above work fine for me.  E.g.,

    R> l = list(a=new.env(), b=new.env())
    R> unique(l)

   > [[1]] <environment: 0x55695f2f6d20>

   > [[2]] <environment: 0x55695f2f6930>

   > Best -k

Ditto here;  also your (Jan) 2nd example works fine.

So, you must have loaded some (untidy) packages / code which redefine
standard base R behavior ?

Martin