From: Eli Zaretskii <eliz@gnu.org>
Date: Sun, 20 Jul 2025 08:36:35 +0000 (+0300)
Subject: Improve error message for "C-u M-! something &"
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=e61e6d279699f4a4e51254e42843e24b24f380aa;p=emacs.git

Improve error message for "C-u M-! something &"

* lisp/simple.el (shell-command): User-friendlier error message
when async shell command is invoked with a prefix argument.

(cherry picked from commit 852009b4f1c9a821ded0cc566d63395c6986ccaa)
---

diff --git a/lisp/simple.el b/lisp/simple.el
index aaf64fb6adc..62130ce1cf3 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -4577,7 +4577,10 @@ impose the use of a shell (with its need to quote arguments)."
 	;; Output goes in a separate buffer.
 	(if (string-match "[ \t]*&[ \t]*\\'" command)
 	    ;; Command ending with ampersand means asynchronous.
-            (let* ((buffer (get-buffer-create
+            (let* ((_ (or (bufferp output-buffer)
+                          (stringp output-buffer)
+                          (error "Asynchronous shell commands cannot output to current buffer")))
+                   (buffer (get-buffer-create
                             (or output-buffer shell-command-buffer-name-async)))
                    (bname (buffer-name buffer))
                    (proc (get-buffer-process buffer))