Display the exit code if the last command failed in Eshell

* lisp/eshell/esh-io.el (eshell-last-command-status): Make
buffer-local.

* lisp/eshell/em-prompt.el (eshell-prompt-function): Insert the exit
code if last command failed.

* test/lisp/eshell/em-prompt-tests.el (em-prompt-test/after-failure):
New test.
(em-prompt-test/next-previous-prompt-1)
(em-prompt-test/forward-backward-matching-input-1): Add a failing
command to tests.

* doc/misc/eshell.texi (Invocation): Document change.

* etc/NEWS: Announce change (bug#65604).

2 files changed, 3 insertions, 1 deletions

diff --git a/lisp/eshell/em-prompt.el b/lisp/eshell/em-prompt.el
index a5abb75bccc..15b849a4d37 100644
--- a/lisp/eshell/em-prompt.el
+++ b/lisp/eshell/em-prompt.el
@@ -50,6 +50,8 @@ as is common with most shells."
 (defcustom eshell-prompt-function
   (lambda ()
     (concat (abbreviate-file-name (eshell/pwd))
+            (unless (eshell-exit-success-p)
+              (format " [%d]" eshell-last-command-status))
             (if (= (file-user-uid) 0) " # " " $ ")))
   "A function that returns the Eshell prompt string."
   :type 'function
diff --git a/lisp/eshell/esh-io.el b/lisp/eshell/esh-io.el
index c07f871dd37..cd0cee6e21d 100644
--- a/lisp/eshell/esh-io.el
+++ b/lisp/eshell/esh-io.el
@@ -170,7 +170,7 @@ describing the mode, e.g. for using with `eshell-get-target'.")
 
 (defvar eshell-current-handles nil)
 
-(defvar eshell-last-command-status 0
+(defvar-local eshell-last-command-status 0
   "The exit code from the last command.  0 if successful.")
 
 (defvar eshell-last-command-result nil