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bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad
From: |
Noam Postavsky |
Subject: |
bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode |
Date: |
Sat, 11 May 2019 10:06:42 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) |
Alan Mackenzie <acm@muc.de> writes:
[rearranged a bit for better flow]
>> Right, the problem is that electric-indent-inhibit only partially
>> disables electric indent, and the commit you reference changes which
>> parts. The patch below disables it more completely. Note however, that
>> this makes RET not do any electric indentation at all, just like in the
>> good old days of Emacs 24.3.
>> Subject: [PATCH] Inhibit electric indent completely in cc mode buffers
>
>> Electric indent mode's post-self-insert hook entry has 3 effects:
>
>> 1. Indent the previous line.
>> 2. Remove trailing whitespace from the previous line.
>> 3. Indent the current line (when at beginning of line).
> I don't quite agree with this. The problem is confusion between effect
> 2 [above] and electric indentation. This effect 2 is fundamental editor
> functionality, and should be independent, MUST be independent of anything
> called "electric indentation". The two things are conceptually
> unrelated.
So we should have an electric-delete-trailing-whitespace-mode?
>> The change from 2019-01-22 "electric-layout-mode kicks in before
>> electric-pair-mode", makes 'electric-indent-inhibit' inhibit 1 and 2,
>> whereas before then it inhibited only 1. While cc mode provides its
>> own electric commands and therefore sets 'electric-indent-inhibit', it
>> doesn't implement an electric newline command. So if only one of
>> effects 2 and 3 from Electric indent mode occur, then hitting RET will
>> leave trailing whitespace.
>
>> * lisp/progmodes/cc-mode.el (c-electric-indent-mode-function): New
>> function.
>> (c-basic-common-init): Add it to electric-indent-functions to disable
>> electric indent completely (while still letting the
>> electric-indent-mode command/setting to control c-electric-flag as
>> before).
>> (when (boundp 'electric-indent-inhibit) (setq electric-indent-inhibit t))
>> + (add-hook 'electric-indent-functions 'c-electric-indent-mode-function nil
>> t)
>> +(defun c-electric-indent-mode-function (char)
>> + ;; We never want `electric-indent-mode' to do anything.
>> + 'no-indent)
> I'm against this patch. It is an unpleasant workaround in CC Mode for
> problems in the Emacs core. CC Mode has set electric-indent-inhibit to
> t, and the Emacs core should respect that setting. Using
> electric-indent-functions in the way suggested couples CC Mode
> undesirably with electric indentation, possibly leading to future
> problems when electric indentation gets changed in the future.
Hmm, from my point of view, the whole point of the patch is to
*UNcouple* CC mode from electric.el's electric indentation (since CC
mode has its own electric functionality), something that
electric-indent-inhibit does only partially (and based on your response
above I guess the reason for being partial is that there is some
disagreement over which parts exactly constitute "electric
indentation").
>> Possibly c-mode should rebind RET to a c-electric-return command or
>> something.
>
> CC Mode should be able to rely on the proper working of basic editor
> functionality. It shouldn't have to implement its own version of
> `newline'.
> In previous Emacs versions (?23.x, ?24.x) there were two simple commands
> `newline' and `newline-and-indent'. As far as I remember, they both
> removed trailing WS from the "old" line, possibly as part of the filling
> which was done. They worked, and worked well. Why can't we get this
> functionality back again?
Both these commands still exist. As far as I can tell, `newline' never
removed trailing WS. It does have some code to delete the "left
margin", but that doesn't seem to be intended for programming modes
where the margin is 0 (disabled).
`newline-and-indent' did, and still does, delete trailing whitespace.
In 24.4, C-j was rebound from `newline-and-indent' to
`electric-newline-and-maybe-indent' which only calls
`newline-and-indent' if `electric-indent-mode' is nil. Of course c-mode
could rebind it in its mode map (I considered making
`electric-newline-and-maybe-indent' consult `electric-indent-functions'
as well but that won't work because that hook is supposed to run after
the character is inserted).
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Noam Postavsky, 2019/05/10
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Alan Mackenzie, 2019/05/11
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode,
Noam Postavsky <=
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Alan Mackenzie, 2019/05/11
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Basil L. Contovounesios, 2019/05/11
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Alan Mackenzie, 2019/05/12
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Basil L. Contovounesios, 2019/05/12
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Alan Mackenzie, 2019/05/13
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Basil L. Contovounesios, 2019/05/13
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Alan Mackenzie, 2019/05/12
- bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Noam Postavsky, 2019/05/12
bug#35254: 27.0.50; cc-mode/electric-pair-mode/electric-layout-mode: bad trailing whitespace behavior in cc-mode, Alan Mackenzie, 2019/05/13