* bug#61925: 30.0.50; normal-mode does not set up local variables in temporary buffers (scratch, with-temp-buffer)
2023-03-04 10:19 ` Eli Zaretskii
@ 2023-03-05 4:58 ` Wolfgang Scherer
2023-03-05 5:03 ` Wolfgang Scherer
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Wolfgang Scherer @ 2023-03-05 4:58 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: 61925
> tags 61925 notabug
> thanks
>
>> Date: Fri, 3 Mar 2023 00:11:13 +0100
>> From: Wolfgang Scherer <Wolfgang.Scherer@gmx.de>
>>
>> The command `normal-mode' does not set file local variables, if a
>> buffer does not have a `buffer-file-name'. This affects *scratch* and
>> buffers created using `with-temp-buffer'.
>>
>> The behavior changed at some time between Emacs version 20.5.2.2 and 20.6.3.
>> See output from various Emacs versions further below.
>>
>> If that was an intentional change, it should be prominently documented
>> to avoid the confusion when examples do not work in a *scratch* buffer.
> This was an intentional change, yes.
Alright, in this case, I would like to publish an advice which restores
the previous behavior for anybody running into the same problem:
(let* ((expected-value (not (default-value 'truncate-lines)))
(need-advice (with-temp-buffer
(insert (format (concat ";; -*-"
" mode: fudamental-mode;"
" truncate-lines: %S;"
" -*-")
expected-value))
(normal-mode)
(not (eq truncate-lines expected-value)))))
(when need-advice
(defadvice normal-mode (around wsx-normal-mode activate)
"Bind buffer-file-name to `null-device', if it is nil."
(let ((buffer-file-name (or buffer-file-name null-device "/dev/null")))
ad-do-it))))
> And AFAICT, it _is_ documented in the ELisp Reference manual:
>
> -- Command: normal-mode &optional find-file
> This function establishes the proper major mode and buffer-local
> variable bindings for the current buffer. It calls ‘set-auto-mode’
> (see below). As of Emacs 26.1, it no longer runs
> ‘hack-local-variables’, this now being done in ‘run-mode-hooks’ at
> the initialization of major modes (*note Mode Hooks::).
>
> And the documentation of run-mode-hooks says:
>
>
> -- Function: run-mode-hooks &rest hookvars
> Major modes should run their mode hook using this function. It is
> similar to ‘run-hooks’ (*note Hooks::), but it also runs
> ‘change-major-mode-after-body-hook’, ‘hack-local-variables’ (when
> the buffer is visiting a file) (*note File Local Variables::) ^^^^
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> The user manual indeed didn't mention this caveat; I've now mentioned
> that aspect there (and also in the doc strings of the relevant
> functions).
>
> (The change in Emacs 26 that caused this as a side effect was to fix
> bug#15577 and bug#23407.)
>
>> I would even recommend a warning prompt in normal-mode, when called
>> interactively.
> I think such a warning could be an annoyance.
It most definitely should be, to get the proper attention. It
could be disabled by setting a customized variable, pretty much
the same way as risky local variables can be enabled with custom
settings. That would reduce the annoyance to once in a session or
once in a lifetime.
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug#61925: 30.0.50; normal-mode does not set up local variables in temporary buffers (scratch, with-temp-buffer)
2023-03-04 10:19 ` Eli Zaretskii
2023-03-05 4:58 ` Wolfgang Scherer
@ 2023-03-05 5:03 ` Wolfgang Scherer
2023-03-06 2:07 ` Wolfgang Scherer
2024-01-10 11:08 ` Stefan Kangas
3 siblings, 0 replies; 6+ messages in thread
From: Wolfgang Scherer @ 2023-03-05 5:03 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: 61925
> And AFAICT, it _is_ documented in the ELisp Reference manual:
>
> -- Command: normal-mode &optional find-file
> This function establishes the proper major mode and buffer-local
> variable bindings for the current buffer. It calls ‘set-auto-mode’
> (see below). As of Emacs 26.1, it no longer runs
> ‘hack-local-variables’, this now being done in ‘run-mode-hooks’ at
> the initialization of major modes (*note Mode Hooks::).
>
> And the documentation of run-mode-hooks says:
>
>
> -- Function: run-mode-hooks &rest hookvars
> Major modes should run their mode hook using this function. It is
> similar to ‘run-hooks’ (*note Hooks::), but it also runs
> ‘change-major-mode-after-body-hook’, ‘hack-local-variables’ (when
> the buffer is visiting a file) (*note File Local Variables::) ^^^^
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Just for your information, the machinery in `normal-mode' and
`run-mode-hooks' is -- at least in some edge cases -- out of
sync.
Here is a case, where normal-mode in Emacs > 26.1 still calls
`hack-local-variables', which causes a discrepancy, depending on
`delay-mode-hooks', when `after-change-major-mode-hook' alters
the value of a local variable, which is also set in the local
variables list. The reason is, that in `normal-mode'
`after-change-major-mode-hook' is not called the same way as it
is in `run-mode-hooks'.
;; for all cases: `after-change-major-mode-hook' establishes local
;; variable and sets the value to "hello"
;; case 1: buffer with `buffer-file-name' == nil, `delay-mode-hooks' case 1.1: nil, case 1.2: t
(check-normal-mode-in-temp-buffer nil nil nil t ) ::go:: ;; => hello
(check-normal-mode-in-temp-buffer t nil nil t ) ::go:: ;; => good-bye
;; case 2: buffer with `buffer-file-name' not nil, `delay-mode-hooks' case 2.1: nil, case 2.2: t
(check-normal-mode-in-temp-buffer nil t nil t ) ::go:: ;; => hello
(check-normal-mode-in-temp-buffer t t nil t ) ::go:: ;; => good-bye
The following is the complete test setup that I used for testing:
(defun check-normal-mode (&optional set-delay-mode-hooks set-buffer-file-name find-file)
(interactive)
(let ((buffer-file-name (or buffer-file-name (and set-buffer-file-name (or null-device "/dev/null"))))
(delay-mode-hooks (if set-delay-mode-hooks t)))
(normal-mode find-file)))
(defun check-normal-mode-in-temp-buffer (set-delay-mode-hooks set-buffer-file-name change-hook after-hook)
(let ((hook-function #'(lambda () (make-local-variable 'wsx-here-i-am) (setq wsx-here-i-am "hello"))))
(if change-hook
(add-hook 'change-major-mode-after-body-hook hook-function)
(remove-hook 'change-major-mode-after-body-hook hook-function))
(if after-hook
(add-hook 'after-change-major-mode-hook hook-function)
(remove-hook 'after-change-major-mode-hook hook-function))
(put 'wsx-here-i-am 'safe-local-variable 'string-or-null-p)
(with-temp-buffer
(insert ";; -*- mode: lisp-interaction; truncate-lines: t; wsx-here-i-am: \"good bye\"; -*-\n")
(normal-mode)
(check-normal-mode set-delay-mode-hooks set-buffer-file-name)
(describe-variable 'wsx-here-i-am)
)
(remove-hook 'change-major-mode-after-body-hook hook-function)
(remove-hook 'after-change-major-mode-hook hook-function)
(put 'wsx-here-i-am 'safe-local-variable nil)))
;; Emacs >= 26.1
(check-normal-mode-in-temp-buffer nil nil nil nil) ::go:: ;; => void
(check-normal-mode-in-temp-buffer t nil nil nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil t nil nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer t t nil nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil nil t nil) ::go:: ;; => hello
(check-normal-mode-in-temp-buffer t nil t nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil t t nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer t t t nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil nil nil t ) ::go:: ;; => hello
(check-normal-mode-in-temp-buffer t nil nil t ) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil t nil t ) ::go:: ;; => hello
(check-normal-mode-in-temp-buffer t t nil t ) ::go:: ;; => good-bye
;; Emacs < 26.1
(check-normal-mode-in-temp-buffer nil nil nil nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer t nil nil nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil t nil nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer t t nil nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil nil t nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer t nil t nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil t t nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer t t t nil) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil nil nil t ) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer t nil nil t ) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer nil t nil t ) ::go:: ;; => good-bye
(check-normal-mode-in-temp-buffer t t nil t ) ::go:: ;; => good-bye
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug#61925: 30.0.50; normal-mode does not set up local variables in temporary buffers (scratch, with-temp-buffer)
2023-03-04 10:19 ` Eli Zaretskii
2023-03-05 4:58 ` Wolfgang Scherer
2023-03-05 5:03 ` Wolfgang Scherer
@ 2023-03-06 2:07 ` Wolfgang Scherer
2024-01-10 11:08 ` Stefan Kangas
3 siblings, 0 replies; 6+ messages in thread
From: Wolfgang Scherer @ 2023-03-06 2:07 UTC (permalink / raw)
To: 61925
The corrected version of the advice fixes the invalid mode specification.
(let* ((expected-value (not (default-value 'truncate-lines)))
(need-advice (with-temp-buffer
(insert (format (concat ";; -*-"
" mode: fundamental;"
" truncate-lines: %S;"
" -*-")
expected-value))
(normal-mode)
(not (eq truncate-lines expected-value)))))
(when need-advice
(defadvice normal-mode (around wsx-normal-mode activate)
"Bind buffer-file-name to `null-device', if it is nil."
(let ((buffer-file-name (or buffer-file-name null-device "/dev/null")))
ad-do-it))))
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug#61925: 30.0.50; normal-mode does not set up local variables in temporary buffers (scratch, with-temp-buffer)
2023-03-04 10:19 ` Eli Zaretskii
` (2 preceding siblings ...)
2023-03-06 2:07 ` Wolfgang Scherer
@ 2024-01-10 11:08 ` Stefan Kangas
3 siblings, 0 replies; 6+ messages in thread
From: Stefan Kangas @ 2024-01-10 11:08 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: 61925-done, Wolfgang Scherer
Eli Zaretskii <eliz@gnu.org> writes:
> tags 61925 notabug
> thanks
>
>> Date: Fri, 3 Mar 2023 00:11:13 +0100
>> From: Wolfgang Scherer <Wolfgang.Scherer@gmx.de>
>>
>> The command `normal-mode' does not set file local variables, if a
>> buffer does not have a `buffer-file-name'. This affects *scratch* and
>> buffers created using `with-temp-buffer'.
>>
>> The behavior changed at some time between Emacs version 20.5.2.2 and 20.6.3.
>> See output from various Emacs versions further below.
>>
>> If that was an intentional change, it should be prominently documented
>> to avoid the confusion when examples do not work in a *scratch* buffer.
>
> This was an intentional change, yes.
>
> And AFAICT, it _is_ documented in the ELisp Reference manual:
>
> -- Command: normal-mode &optional find-file
> This function establishes the proper major mode and buffer-local
> variable bindings for the current buffer. It calls ‘set-auto-mode’
> (see below). As of Emacs 26.1, it no longer runs
> ‘hack-local-variables’, this now being done in ‘run-mode-hooks’ at
> the initialization of major modes (*note Mode Hooks::).
>
> And the documentation of run-mode-hooks says:
>
>
> -- Function: run-mode-hooks &rest hookvars
> Major modes should run their mode hook using this function. It is
> similar to ‘run-hooks’ (*note Hooks::), but it also runs
> ‘change-major-mode-after-body-hook’, ‘hack-local-variables’ (when
> the buffer is visiting a file) (*note File Local Variables::) ^^^^
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> The user manual indeed didn't mention this caveat; I've now mentioned
> that aspect there (and also in the doc strings of the relevant
> functions).
>
> (The change in Emacs 26 that caused this as a side effect was to fix
> bug#15577 and bug#23407.)
>
>> I would even recommend a warning prompt in normal-mode, when called
>> interactively.
>
> I think such a warning could be an annoyance.
It seems like we're not going to be making any changes here, as this is
the expected behavior.
I'm therefore closing this bug report.
^ permalink raw reply [flat|nested] 6+ messages in thread