GNU bug report logs -
#31361
25.3; Issue when advising `indent-line-function'
Previous Next
To reply to this bug, email your comments to 31361 AT debbugs.gnu.org.
Toggle the display of automated, internal messages from the tracker.
Report forwarded
to
monnier <at> IRO.UMontreal.CA, bug-gnu-emacs <at> gnu.org
:
bug#31361
; Package
emacs
.
(Thu, 03 May 2018 21:17:02 GMT)
Full text and
rfc822 format available.
Acknowledgement sent
to
Nicolas Goaziou <mail <at> nicolasgoaziou.fr>
:
New bug report received and forwarded. Copy sent to
monnier <at> IRO.UMontreal.CA, bug-gnu-emacs <at> gnu.org
.
(Thu, 03 May 2018 21:17:02 GMT)
Full text and
rfc822 format available.
Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):
Hello,
When `indent-line-function' is advised, using `add-function', and the
variable contains `indent-relative', `indent-according-to-mode' has an
erratic behavior.
In the following code, from `indent-according-to-mode',
(if (memq indent-line-function
'(indent-relative indent-relative-maybe))
...
;; The normal case.
(funcall indent-line-function))
the if branch is no longer executed because `indent-line-function' is no
longer `indent-relative' but a closure around it.
You can reproduce the issue with the following recipe:
- Open a new buffer in Fundamental mode (so `indent-line-function' is
`indent-relative')
- Insert : "-- Test"
- From there, <RET> returns to column 0. However, upon evaluating the
following:
M-: (add-function :before-until (local 'indent-line-function) #'ignore)
<RET> now moves point at the same column as the "T" from "Test", in
the new line.
Regards,
--
Nicolas Goaziou 0x80A93738
Information forwarded
to
bug-gnu-emacs <at> gnu.org
:
bug#31361
; Package
emacs
.
(Sat, 05 May 2018 14:27:02 GMT)
Full text and
rfc822 format available.
Message #8 received at 31361 <at> debbugs.gnu.org (full text, mbox):
Nicolas Goaziou <mail <at> nicolasgoaziou.fr> writes:
> When `indent-line-function' is advised, using `add-function', and the
> variable contains `indent-relative', `indent-according-to-mode' has an
> erratic behavior.
>
> In the following code, from `indent-according-to-mode',
>
> (if (memq indent-line-function
> '(indent-relative indent-relative-maybe))
> ...
> ;; The normal case.
> (funcall indent-line-function))
>
> the if branch is no longer executed because `indent-line-function' is no
> longer `indent-relative' but a closure around it.
Thinking more about the problem, I think I can describe it differently.
When `indent-line-function' is set to `indent-relative' -- or
`indent-relative-maybe' -- the function `indent-relative' is not meant
to be actually called to handle the indentation. Instead, some ad-hoc
indentation is hard-coded into `indent-according-to-mode', which see.
However, when `indent-line-function' is advised, according to my
previous report, `indent-relative' is actually called for indentation,
which is not the intent, per above.
So basically, any call to `indent-according-to-mode', e.g., with
`reindent-then-newline-and-indent' or through Electric Indent mode, is
broken whenever `indent-relative' is advised.
One idea, suggested by Stefan, would be to write
`indent-according-to-mode' like the following:
(if (memq (advice--cd*r indent-line-function)
'(indent-relative indent-relative-maybe))
...
;; The normal case.
(funcall indent-line-function))
i.e., strip advices so that the ad-hoc code is executed, as intended,
instead of ultimately calling `indent-relative'. Unfortunately, this is
insufficient because the advices are not applied, which is also wrong.
If this stripping is done, it should also ensure that advices are
applied on the ad-hoc indentation code there.
FWIW, my gut feeling is that `indent-relative' -- and
`indent-relative-maybe' -- ought to be normalized to behave like
a normal indentation function, i.e., a function actually called from
`indent-according-to-mode'. This was the case before commit
a17b712b4d812d28086ae9af02f9043b36cf3e19 (Oct 30 2001).
Currently, `indent-relative' is two-sided. Therefore, the previous
suggestion might entail to split `indent-relative' into two parts, one
meant to be used as a value for `indent-line-function' -- maybe named
`indent-relative-function' -- and the other one to be used like current
`indent-relative', i.e., jumping from one indent point to the other.
This bug report was last modified 6 years and 233 days ago.
Previous Next
GNU bug tracking system
Copyright (C) 1999 Darren O. Benham,
1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.