From 21d1b727413e8649436431806ec6a2731c9fd28b Mon Sep 17 00:00:00 2001
From: Jim Porter <jporterbugs@gmail.com>
Date: Mon, 24 Jan 2022 21:08:50 -0800
Subject: [PATCH 2/2] Treat "-" as a positional arg in
 'eshell-eval-using-options'

* lisp/eshell/esh-opt.el (eshell--process-args): Treat "-" as a
positional arg.

* lisp/eshell/em-tramp.el (eshell/su): Simplify checking for "-".

* test/lisp/eshell/esh-opt-tests.el
(esh-opt-test/eval-using-options-stdin): New test.
---
 lisp/eshell/em-tramp.el           |  9 ++-------
 lisp/eshell/esh-opt.el            |  9 ++++++---
 test/lisp/eshell/esh-opt-tests.el | 21 +++++++++++++++++++++
 3 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/lisp/eshell/em-tramp.el b/lisp/eshell/em-tramp.el
index 791458822d..2afd4fe066 100644
--- a/lisp/eshell/em-tramp.el
+++ b/lisp/eshell/em-tramp.el
@@ -57,13 +57,12 @@ eshell-tramp-initialize
 
 (autoload 'eshell-parse-command "esh-cmd")
 
-(defun eshell/su (&rest arguments)
+(defun eshell/su (&rest args)
   "Alias \"su\" to call TRAMP.
 
 Uses the system su through TRAMP's su method."
-  (setq arguments (eshell-stringify-list (flatten-tree arguments)))
   (eshell-eval-using-options
-   "su" arguments
+   "su" args
    '((?h "help" nil nil "show this usage screen")
      (?l "login" nil login "provide a login environment")
      (?  nil nil login "provide a login environment")
@@ -77,10 +76,6 @@ eshell/su
                 (prefix (file-remote-p default-directory)))
             (dolist (arg args)
               (if (string-equal arg "-") (setq login t) (setq user arg)))
-            ;; `eshell-eval-using-options' tries to handle "-" as a
-            ;; short option; double-check whether the original
-            ;; arguments include it.
-            (when (member "-" arguments) (setq login t))
             (when login (setq dir "~/"))
             (if (and prefix
                      (or
diff --git a/lisp/eshell/esh-opt.el b/lisp/eshell/esh-opt.el
index 8c29fff809..0961e214f4 100644
--- a/lisp/eshell/esh-opt.el
+++ b/lisp/eshell/esh-opt.el
@@ -283,6 +283,9 @@ eshell--process-args
                           (memq :parse-leading-options-only options))))
       (setq arg (nth ai eshell--args))
       (if (not (and (stringp arg)
+                    ;; A string of length 1 can't be an option; (if
+                    ;; it's "-", that generally means stdin).
+                    (> (length arg) 1)
 		    (string-match "^-\\(-\\)?\\(.*\\)" arg)))
           ;; Positional argument found, skip
 	  (setq ai (1+ ai)
@@ -295,9 +298,9 @@ eshell--process-args
 	      (if (> (length switch) 0)
 		  (eshell--process-option name switch 1 ai options opt-vals)
 		(setq ai (length eshell--args)))
-	      (while (> (length switch) 0)
-		(setq switch (eshell--process-option name switch 0
-                                                     ai options opt-vals)))))))
+	    (while (> (length switch) 0)
+	      (setq switch (eshell--process-option name switch 0
+                                                   ai options opt-vals)))))))
     (nconc (mapcar #'cdr opt-vals) eshell--args)))
 
 (provide 'esh-opt)
diff --git a/test/lisp/eshell/esh-opt-tests.el b/test/lisp/eshell/esh-opt-tests.el
index 4331c02ff5..5b30de414a 100644
--- a/test/lisp/eshell/esh-opt-tests.el
+++ b/test/lisp/eshell/esh-opt-tests.el
@@ -182,6 +182,27 @@ esh-opt-test/eval-using-options-short-single-token
    (should (equal ignore-pattern "*.txt"))
    (should (equal args '("/some/path")))))
 
+(ert-deftest esh-opt-test/eval-using-options-stdin ()
+  "Test that \"-\" is a positional arg in `eshell-eval-using-options'."
+  (eshell-eval-using-options
+   "cat" '("-")
+   '((?A "show-all" nil show-all
+         "show all characters"))
+   (should (eq show-all nil))
+   (should (equal args '("-"))))
+  (eshell-eval-using-options
+   "cat" '("-A" "-")
+   '((?A "show-all" nil show-all
+         "show all characters"))
+   (should (eq show-all t))
+   (should (equal args '("-"))))
+  (eshell-eval-using-options
+   "cat" '("-" "-A")
+   '((?A "show-all" nil show-all
+         "show all characters"))
+   (should (eq show-all t))
+   (should (equal args '("-")))))
+
 (ert-deftest esh-opt-test/eval-using-options-terminate-options ()
   "Test that \"--\" terminates options in `eshell-eval-using-options'."
   (eshell-eval-using-options
-- 
2.25.1