[ESS] Emacs can find R-devel and R-newest, but not R-4.0.x

[Martin Maechler]

>>>>> Colin Baxter via ESS-help 
>>>>>     on Thu, 26 Nov 2020 06:14:45 +0000 writes:

>>>>> Tyler Smith via ESS-help <ess-help using r-project.org> writes:
    >> This was fixed in ESS 19.04. If you install/update ESS
    >> from Melpa, you should get a recent version that includes
    >> this fix.

    > ??? I have pulled ESS from git and M-x ESS-version <RET>
    > gives 18.10.3snapshot. Does this mean ESS from git lags
    > behind Melpa?

No.  Marius was using the last released version of ESS  which
indeed we forgot to equip with searching for R-4....

Marius:  The fastest may be to just replace this in the ESS 18.10 sources :

In file  lisp/ess-r-mode.el,  find

(defvar ess-r-versions
  (let ((r-ver '("R-1" "R-2" "R-3" "R-devel" "R-patched")))

and replace the 2nd line by

  (let ((r-ver '("R-1" "R-2" "R-3" "R-4" "R-5" "R-6" "R-7" "R-devel" "R-patched")))

NB:  In newer  (all development) versions of ESS  ess-r-versions
still exists but is deprecated in favor of

   ess-r-runner-prefixes

which is also *customizable*.

----

"Yes", the non-released development versions of ESS have nice new
features but also some new bugs which I've hoped for a long time
would be gone before a  new official release... (and partly
*have* been removed).

Another reason preventing a new release has been that the
*.Rnw *.Rmd  (Sweave, knitr, Rmarkdown, ..)  support ("*noweb") in ESS
has been deprecated in favor of the new poly-mode based emacs
lisp packages.  ... and the plan has been that  an   "ESS+" bundle
should be have been ready when ESS is released, where the ESS+
"bundle" / 'meta-package' should contain  ESS + polymode + ...
so that people and upstream "package" maintainers (for Debian
Linux, SuSE, Redhat; or Vincent Goulet's "Emacs+ESS+.." bundle)
could use ESS+ too.

Martin Maechler
ETH Zurich   and  ESS core team