[ESS] Following up, success! [was RE: [R-win] Difficulty installing R packages under Windows 11 / Cygwin]

[Robert Lerche]

Yes and thanks for responding.  That is I think exactly what's needed and I have taken a shot at implementing it.  [I'm glad my previous attached patch got filtered, I was a bit careless.]  Here's a summary of what I've done:

ess-custom.el: extract prefix using cygpath, set to nil if error (i.e., no cygpath command indicates not in Cygwin)
ess-inf.el: add prefix to initial setcwd()
ess-r-mode.el: add prefix to path sent to R for initialization (I know my change to ess-r--load-ESSR-local is right, I'm not sure about ess-r--fetch-ESSR-remote)

---
diff --git a/lisp/ess-custom.el b/lisp/ess-custom.el
index f631e04d..e4db36c0 100644
--- a/lisp/ess-custom.el
+++ b/lisp/ess-custom.el
@@ -2489,6 +2489,11 @@ Used to store the values for passing on to newly created buffers.")
 (defvar ess-STERM nil
   "Placeholder for dialect-specific STERM.")
 
+(defvar ess-cygwin-prefix
+  (condition-case nil (nth 0 (process-lines "cygpath"  "-m" "/"))
+    (error nil))
+  "For Windows compatibility, prefix paths passed to R with this")
+
 (make-obsolete-variable 'ess-S-loop-timeout "It is ignored." "ESS 18.10")
 (make-obsolete-variable 'ess-mode-load-hook "It is ignored." "ESS 18.10")
 (make-obsolete-variable 'ess-speedbar-use-p "It is ignored." "ESS 18.10")
diff --git a/lisp/ess-inf.el b/lisp/ess-inf.el
index 9ca3f455..9b611934 100644
--- a/lisp/ess-inf.el
+++ b/lisp/ess-inf.el
@@ -3046,7 +3046,7 @@ NO-ERROR prevents errors when this has not been implemented for
                      path))
              (lpath (if remote
                         (with-parsed-tramp-file-name path v v-localname)
-                      path)))
+                      (concat ess-cygwin-prefix path))))
         (ess-eval-linewise (format ess-setwd-command lpath))
         (ess-set-process-variable 'default-directory
                                   (file-name-as-directory path)))
diff --git a/lisp/ess-r-mode.el b/lisp/ess-r-mode.el
index bd902710..7c093763 100644
--- a/lisp/ess-r-mode.el
+++ b/lisp/ess-r-mode.el
@@ -1572,7 +1572,7 @@ Source the etc/ESSR/.load.R file into the R process. The
 .ess.ESSR.load function sources all of the contents of the
 etc/ESSR/R directory into the ESSR environment and attaches the
 environment to the search path."
-  (let* ((src-dir (expand-file-name "ESSR/R" ess-etc-directory))
+  (let* ((src-dir (concat ess-cygwin-prefix (expand-file-name "ESSR/R" ess-etc-directory)))
          (buf (ess-command (ess-r--load-ESSR-command src-dir))))
     (with-current-buffer buf
       (let ((msg (buffer-string)))
@@ -1614,7 +1614,7 @@ environment from GitHub and attaches it to the search path. If
 the file already exists on disk from a previous download then the
 download step is omitted. This function returns t if the ESSR
 load is successful, and nil otherwise."
-  (let ((loader (ess-file-content (expand-file-name "ESSR/LOADREMOTE" ess-etc-directory)))
+  (let ((loader (ess-file-content (concat ess-cygwin-prefix (expand-file-name "ESSR/LOADREMOTE" ess-etc-directory))))
         (essr (or essr-version
                   ;; FIXME: Hack: on MELPA essr-version is not set
                   (lm-with-file (expand-file-name "ess.el" ess-lisp-directory)

From: Sparapani, Rodney <rsparapa using mcw.edu> 
Sent: Wednesday, January 3, 2024 11:45 AM
To: Robert Lerche <rlerche using pacificbiosciences.com>; Dirk Eddelbuettel <edd using debian.org>; Tomas Kalibera <tomas.kalibera using gmail.com>
Cc: ess-help (ess-help using r-project.org) <ess-help using r-project.org>
Subject: Re: Following up, success! [was RE: [ESS] [R-win] Difficulty installing R packages under Windows 11 / Cygwin]

[EXTERNAL MESSAGE] Be mindful when clicking links or attachments
Hi Robert:

Looking this over.  The issue appears to be that you need a prefix.
It has been a long time since I used Cygwin.  But I assume the
prefix is something like "c:" or "/cygwin/c".  In other words, 
the root is NOT "/"; rather something like $PREFIX/  Is that the issue?
I'm trying to think of a way that we could easily adapt to this
without hacking all over the places.  Possibly, we could support
PREFIX kind of like the way configure works.  Thanks

-- 
Rodney Sparapani, Associate Professor of Biostatistics, He/Him/His
Vice President, Wisconsin Chapter of the American Statistical Association
Institute for Health and Equity, Division of Biostatistics
Medical College of Wisconsin, Milwaukee Campus

From: Robert Lerche <mailto:rlerche using pacificbiosciences.com>
Date: Tuesday, January 2, 2024 at 7:00 PM
To: Dirk Eddelbuettel <mailto:edd using debian.org>, Tomas Kalibera <mailto:tomas.kalibera using gmail.com>
Cc: Sparapani, Rodney <mailto:rsparapa using mcw.edu>, ess-help (mailto:ess-help using r-project.org) <mailto:ess-help using r-project.org>
Subject: Following up, success! [was RE: [ESS] [R-win] Difficulty installing R packages under Windows 11 / Cygwin]
ATTENTION: This email originated from a sender outside of MCW. Use caution when clicking on links or opening attachments.
________________________________

It turns out it was fairly easy to make ESS work in Cygwin Emacs with R built for Windows.  The issue was of course path names.  I attach a patch that works for me.

Let me explain that I am using a company-provided and managed laptop and I have no choice but to run Windows. I am familiar with a number of Unix/Linux -like environments for Windows (Cygwin, MSYS, WSL). I have tried them all over a period of years. I use R primarily as a means for presenting data.  It is not the main thrust of my work.  Having spent considerable time making this laptop a comfortable working environment I am loathe to switch.