bug#59956: 29.0.60: Failure when completing arguments in Eshell after variable interpolation

[Gregory Heytings]

> The more I think about it, the more my workaround sounds appealing.

What do you think of this (based on Augusto's suggestion)?  It seems to me 
that it's a more elegant workaround, with which further improvements 
become possible, which isn't the case if we squeeze the value into a 
string.


diff --git a/lisp/pcomplete.el b/lisp/pcomplete.el
index 4e3a88bbda8..2a2bbf114e0 100644
--- a/lisp/pcomplete.el
+++ b/lisp/pcomplete.el
@@ -645,13 +645,25 @@ pcomplete-arg

 The OFFSET argument is added to/taken away from the index that will be
 used.  This is really only useful with `first' and `last', for
-accessing absolute argument positions."
-  (nth (+ (pcase index
-          ('first 0)
-          ('last  pcomplete-last)
-          (_      (- pcomplete-index (or index 0))))
-         (or offset 0))
-       pcomplete-args))
+accessing absolute argument positions.
+
+When the INDEXth argument has been transformed into something
+that is not a string by `pcomplete-parse-arguments-function', the
+text representation of the argument is returned, and its value is
+stored in its pcomplete-arg-value text property."
+  (let ((arg
+         (nth (+ (pcase index
+                  ('first 0)
+                  ('last  pcomplete-last)
+                  (_      (- pcomplete-index (or index 0))))
+                (or offset 0))
+              pcomplete-args)))
+    (if (stringp arg)
+        arg
+      (propertize
+       (buffer-substring (pcomplete-begin index offset)
+                         (pcomplete-begin (1- (or index 0)) offset))
+       'pcomplete-arg-value arg))))

 (defun pcomplete-begin (&optional index offset)
   "Return the beginning position of the INDEXth argument.