From 6df2941c1b0d965afc40f8c50ce08e45e060d64c Mon Sep 17 00:00:00 2001
From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Sun, 2 Apr 2023 17:54:02 -0400
Subject: [PATCH] lisp/simple.el (inhibit-auto-fill): New var

* lisp/simple.el (inhibit-auto-fill): New var.
(internal-auto-fill): Obey it.
(newline): Use it instead of binding `auto-fill-function`, so
as to avoid messing up the state if something wants to enable/disable
`auto-fill-mode` during the course of the let binding (bug#62419).
---
 etc/NEWS       |  2 ++
 lisp/simple.el | 12 ++++++++----
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 67e1a02d587..d20d9f65ac9 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -319,6 +319,8 @@ hooks named after the feature name, like 'esh-mode-unload-hook'.
 
 * Lisp Changes in Emacs 30.1
 
+** New var 'inhibit-auto-fill' to temporarily prevent auto-fill.
+
 ** Functions and variables to transpose sexps
 
 +++
diff --git a/lisp/simple.el b/lisp/simple.el
index 1447c7e53ff..b621e1603bd 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -623,7 +623,7 @@ A non-nil INTERACTIVE argument means to run the `post-self-insert-hook'."
          (beforepos (point))
          (last-command-event ?\n)
          ;; Don't auto-fill if we have a prefix argument.
-         (auto-fill-function (if arg nil auto-fill-function))
+         (inhibit-auto-fill (or inhibit-auto-fill arg))
          (arg (prefix-numeric-value arg))
          (procsym (make-symbol "newline-postproc")) ;(bug#46326)
          (postproc
@@ -8919,11 +8919,15 @@ unless optional argument SOFT is non-nil."
        ;; If we're not inside a comment, just try to indent.
        (t (indent-according-to-mode))))))
 
+(defvar inhibit-auto-fill nil
+  "Non-nil means to do as if `auto-fill-mode' was disabled.")
+
 (defun internal-auto-fill ()
   "The function called by `self-insert-command' to perform auto-filling."
-  (when (or (not comment-start)
-            (not comment-auto-fill-only-comments)
-            (nth 4 (syntax-ppss)))
+  (unless (or inhibit-auto-fill
+              (and comment-start
+                   comment-auto-fill-only-comments
+                   (not (nth 4 (syntax-ppss)))))
     (funcall auto-fill-function)))
 
 (defvar normal-auto-fill-function 'do-auto-fill
-- 
2.39.2