emacs-29 72c45fa910: Further improvement for non-string values in pcomplete

[Gregory Heytings]

branch: emacs-29
commit 72c45fa9109a53cb55d13697d69e9a32a7e289b5
Author: Gregory Heytings <gregory@heytings.org>
Commit: Gregory Heytings <gregory@heytings.org>

    Further improvement for non-string values in pcomplete
    
    * lisp/pcomplete.el (pcomplete-arg): Use the string representation
    of the argument value instead of the text representation of the
    argument.  Return the value, even when it is not a string, when
    index is 'last'.  Fixes bug#60464.
---
 lisp/pcomplete.el | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/lisp/pcomplete.el b/lisp/pcomplete.el
index 5bee515246..1ca7a21336 100644
--- a/lisp/pcomplete.el
+++ b/lisp/pcomplete.el
@@ -632,6 +632,13 @@ This will modify the current buffer."
 ;;; Internal Functions:
 
 ;; argument handling
+(defsubst pcomplete-actual-arg (&optional index offset)
+  "Return the actual text representation of the last argument.
+This is different from `pcomplete-arg', which returns the textual value
+that the last argument evaluated to.  This function returns what the
+user actually typed in."
+  (buffer-substring (pcomplete-begin index offset) (point)))
+
 (defun pcomplete-arg (&optional index offset)
   "Return the textual content of the INDEXth argument.
 INDEX is based from the current processing position.  If INDEX is
@@ -659,11 +666,20 @@ the pcomplete-arg-value text property of that string."
                   (_      (- pcomplete-index (or index 0))))
                 (or offset 0))
               pcomplete-args)))
-    (if (stringp arg)
+    (if (or (stringp arg)
+            ;; FIXME: 'last' is handled specially in Emacs 29, because
+            ;; 'pcomplete-parse-arguments' accepts a list of strings
+            ;; (which are completion candidates) as return value for
+            ;; (pcomplete-arg 'last).  See below: "it means it's a
+            ;; list of completions computed during parsing,
+            ;; e.g. Eshell uses that to turn globs into lists of
+            ;; completions".  This special case will be dealt with
+            ;; differently in Emacs 30: the pcomplete-arg-value
+            ;; property will be used by 'pcomplete-parse-arguments'.
+            (eq index 'last))
         arg
       (propertize
-       (buffer-substring (pcomplete-begin index offset)
-                         (pcomplete-begin (1- (or index 0)) offset))
+       (car (split-string (pcomplete-actual-arg index offset)))
        'pcomplete-arg-value arg))))
 
 (defun pcomplete-begin (&optional index offset)
@@ -679,13 +695,6 @@ See the documentation for `pcomplete-arg'."
       (setq index (+ index offset)))
   (nth index pcomplete-begins))
 
-(defsubst pcomplete-actual-arg (&optional index offset)
-  "Return the actual text representation of the last argument.
-This is different from `pcomplete-arg', which returns the textual value
-that the last argument evaluated to.  This function returns what the
-user actually typed in."
-  (buffer-substring (pcomplete-begin index offset) (point)))
-
 (defsubst pcomplete-next-arg ()
   "Move the various pointers to the next argument."
   (setq pcomplete-index (1+ pcomplete-index)