During completion, convert all Eshell arguments to strings

Eshell was already converting some types (numbers, nil) to strings, as
well as fixing up multiple-dot forms like ".../", so this way is more
consistent and should produce fewer problems for Pcomplete functions.

* lisp/eshell/em-cmpl.el (eshell-complete-parse-arguments): Always
convert parsed arguments to strings.

* test/lisp/eshell/em-cmpl-tests.el (eshell-arguments-equal,
eshell-arguments-equal--equal-explainer): New functions.
(em-cmpl-test/parse-arguments/pipeline)
(em-cmpl-test/parse-arguments/multiple-dots)
(em-cmpl-test/parse-arguments/variable/numeric)
(em-cmpl-test/parse-arguments/variable/nil)
(em-cmpl-test/parse-arguments/variable/list)
(em-cmpl-test/parse-arguments/variable/splice): Use
'eshell-arguments-equal'.

1 files changed, 13 insertions, 11 deletions

diff --git a/lisp/eshell/em-cmpl.el b/lisp/eshell/em-cmpl.el
index d1c7e81090a..acbf206a3c6 100644
--- a/lisp/eshell/em-cmpl.el
+++ b/lisp/eshell/em-cmpl.el
@@ -386,17 +386,19 @@ to writing a completion function."
     ;; Convert arguments to forms that Pcomplete can understand.
     (cons (mapcar
            (lambda (arg)
-             (cond
-              ((numberp arg)
-               (number-to-string arg))
-              ;; Expand ".../" etc that only Eshell understands to the
-              ;; standard "../../".
-              ((and (stringp arg) (string-match "\\.\\.\\.+/" arg))
-               (eshell-expand-multiple-dots arg))
-              ((null arg)
-               "")
-              (t
-               arg)))
+             (pcase arg
+               ;; Expand ".../" etc that only Eshell understands to
+               ;; the standard "../../".
+               ((rx ".." (+ ".") "/")
+                (propertize (eshell-expand-multiple-dots arg)
+                            'pcomplete-arg-value arg))
+               ((pred stringp)
+                arg)
+               ('nil
+                (propertize "" 'pcomplete-arg-value arg))
+               (_
+                (propertize (eshell-stringify arg)
+                            'pcomplete-arg-value arg))))
            args)
           posns)))