bug#55451: 28.1.50; Executing (jit-lock-mode -1) does not disable jit-lock-mode

[Ihor Radchenko]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>> jit-lock-mode is not a minor mode, so the usual syntax doesn't work
>> with it, and isn't documented to work.  Set it to nil to disable.
>
> The doc string could do with some explicit text about this, so I've
> added that to Emacs 29.  But since this is working as intended, I'm
> closing this bug report.

Thanks! It certainly improves the situation.
However, I am confused why it is impossible to follow +1/-1 convention.
Looking through jit-lock.el I do not see any place where any value other
than non-nil/nil is considered.

A possible patch is attached.

Best,
Ihor

>From a9da60ba42f6745f4bbdb305e057639c40f8d34e Mon Sep 17 00:00:00 2001
Message-Id: 
<a9da60ba42f6745f4bbdb305e057639c40f8d34e.1652874345.git.yantar92@gmail.com>
From: Ihor Radchenko <yantar92@gmail.com>
Date: Wed, 18 May 2022 19:44:25 +0800
Subject: [PATCH] jit-lock-mode: Treat +1 and -1 ARG as other normal minor
 modes

* lisp/jit-lock.el (jit-lock-mode): Recognise +1/-1 arguments using
minor mode conventions.
---
 lisp/jit-lock.el | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lisp/jit-lock.el b/lisp/jit-lock.el
index 20c1202474..224223fc7e 100644
--- a/lisp/jit-lock.el
+++ b/lisp/jit-lock.el
@@ -218,7 +218,12 @@ jit-lock-mode
 the variable `jit-lock-stealth-nice'.
 
 If you need to debug code run from jit-lock, see `jit-lock-debug-mode'."
-  (setq jit-lock-mode arg)
+  (setq jit-lock-mode
+        (pcase arg
+          (`+1 t)
+          (`-1 nil)
+          (`nil nil)
+          (val val)))
   (cond
    ((and (buffer-base-buffer)
          jit-lock-mode)
-- 
2.35.1