emacs-29 dafa6d6bad: Handle non-string values in pcomplete

[Gregory Heytings]

branch: emacs-29
commit dafa6d6badd6552b6f88ba884e3e5dadb362380d
Author: Gregory Heytings <gregory@heytings.org>
Commit: Gregory Heytings <gregory@heytings.org>

    Handle non-string values in pcomplete
    
    * lisp/pcomplete.el (pcomplete-arg): When
    pcomplete-parse-arguments-function returns a non-string value,
    return the string the user typed in, and attach the value as a
    text property to that string.  Fixes bug#59956 and bug#60021.
---
 lisp/pcomplete.el | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/lisp/pcomplete.el b/lisp/pcomplete.el
index 4e3a88bbda..2d3730e294 100644
--- a/lisp/pcomplete.el
+++ b/lisp/pcomplete.el
@@ -645,13 +645,26 @@ parts of the list.
 
 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 argument has been transformed into something that is not
+a string by `pcomplete-parse-arguments-function', the text
+representation of the argument, namely what the user actually
+typed in, is returned, and the value of the argument is stored in
+the pcomplete-arg-value text property of that string."
+  (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.