bug#60643: closed (29.0.50; set-buffer-major-mode resets buffer local variables)

[GNU bug Tracking System]

Your message dated Sun, 08 Jan 2023 01:09:55 -0800
with message-id <87358lqq0n.fsf@breatheoutbreathe.in>
and subject line Re: bug#60643: 29.0.50; set-buffer-major-mode resets buffer 
local variables
has caused the debbugs.gnu.org bug report #60643,
regarding 29.0.50; set-buffer-major-mode resets buffer local variables
to be marked as done.

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-- 
60643: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=60643
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> --- Begin Message ---
>
>
>
> Subject: 
>
> 29.0.50; set-buffer-major-mode resets buffer local variables
>
>
>
>
> Date: 
>
> Sat, 07 Jan 2023 20:48:54 -0800
>
>
>
>
> Hello!
>
> It appears that set-buffer-major-mode resets buffer local variables.
>
> To reproduce with `emacs -Q`:
>
> (defvar-local test-var nil)
> (setq test-var t)
> (message "%s" test-var) ;; t
> ;; (set-auto-mode)
> (set-buffer-major-mode (current-buffer))
> (message "%s" test-var) ;; nil
>
> Is this behavior expected?
>
> Thank you!!
>
> Joseph
>
> In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
> 3.24.30, cairo version 1.16.0)
> Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
> System Description: Debian GNU/Linux 11 (bullseye)
>
> Configured using:
>  'configure
>  
> CONFIG_SHELL=/gnu/store/4y5m9lb8k3qkb1y9m02sw9w9a6hacd16-bash-minimal-5.1.8/bin/bash
>  SHELL=/gnu/store/4y5m9lb8k3qkb1y9m02sw9w9a6hacd16-bash-minimal-5.1.8/bin/bash
>  
> --prefix=/gnu/store/4mnib031vflf88ms8w7kyfahcbv1k9vc-emacs-next-29.0.50-3.22e8a77
>  --enable-fast-install --with-modules --with-cairo
>  --with-native-compilation --disable-build-details'
>
> Configured features:
> ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
> JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES
> NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3
> THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#60643: 29.0.50; set-buffer-major-mode resets buffer local variables
>
>
>
>
> Date: 
>
> Sun, 08 Jan 2023 01:09:55 -0800
>
>
>
>
> Hello!
>
> Eli Zaretskii <eliz@gnu.org> writes:
>
> > Changing the major mode kills all buffer-local variables. If you don't
> > want some variable to be killed, give it the permanent-local property.
>
> Ruijie Yu <ruijie@netyu.xyz> writes:
>
> > There is another concept called "permanent local variables" which you
> > might be thinking about when looking at "local variables", see info node
> > `(elisp) Standard Properties' for more information.
>
> Thank you both for your help!! This solves it:
>
> (put 'test-var 'permanent-local t)
>
> Joseph
>
>
> --- End Message ---