Raise an error from 'eval-eval-using-options' for unknown options

* lisp/eshell/em-basic.el (eshell/echo): Add -E option.

* lisp/eshell/esh-opt.el (eshell--process-option): Raise an error if
an unknown option is encountered, even when :external is nil.

* test/lisp/eshell/esh-opt-tests.el (esh-opt-process-args-test)
(test-eshell-eval-using-options): Add test cases for this.

1 files changed, 9 insertions, 4 deletions

diff --git a/lisp/eshell/em-basic.el b/lisp/eshell/em-basic.el
index d3b15c900b7..ba868cee59e 100644
--- a/lisp/eshell/em-basic.el
+++ b/lisp/eshell/em-basic.el
@@ -113,11 +113,16 @@ or `eshell-printn' for display."
   "Implementation of `echo'.  See `eshell-plain-echo-behavior'."
   (eshell-eval-using-options
    "echo" args
-   '((?n nil (nil) output-newline "do not output the trailing newline")
-     (?N nil (t)   output-newline "terminate with a newline")
-     (?h "help" nil nil "output this help screen")
+   '((?n nil (nil) output-newline
+         "do not output the trailing newline")
+     (?N nil (t)   output-newline
+         "terminate with a newline")
+     (?E nil nil   _disable-escapes
+         "don't interpret backslash escapes (default)")
+     (?h "help" nil nil
+         "output this help screen")
      :preserve-args
-     :usage "[-n | -N] [object]")
+     :usage "[OPTION]... [OBJECT]...")
    (if eshell-plain-echo-behavior
        (eshell-echo args (if output-newline (car output-newline) t))
      ;; In Emacs 28.1 and earlier, "-n" was used to add a newline to