Re: Subversion of user chosen major mode by Emacs.

[Dmitry Gutov <dmitry@gutov.dev>]

Hi Alan,

On 29/05/2024 15:51, Alan Mackenzie wrote:

> On Wed, May 29, 2024 at 14:43:29 +0300, Dmitry Gutov wrote:
>> On 29/05/2024 14:16, Alan Mackenzie wrote:
>>>> I think this is a misfeature of `c-ts-mode.el`, but this was the result
>>>> of a long discussion and I don't think we want to revisit that yet.
>>> Why did nobody involve me in this discussion, considering that the
>>> result involves "stealing" CC Mode users?
> 
>> This behavior is not new: loading a *-ts-mode has been overriding the
>> user preferences since 2023-01-20 (commit 6b2f85caa6).
> 
> That has nothing to do with my point it is supposedly answering.
> 
> I've just had a look at that commit, and it simply adds entries to
> auto-mode-alist for the *-ts-mode modes in the traditional, normal and
> acceptable fashion.  CC Mode does the same.

That's not the same thing: all CC Mode entries are behind ###autoload, 
meaning that the alist does not actually change when you load the file 
(as long as the autoloads are properly generated when you build Emacs).

> The problem comes in a comment in that patch encouraging users to
> subvert the proper meaning of c-mode, etc., from being specific modes to
> being vague generic modes.  This is completely unnecessary for the
> normal user who uses only the *-ts- modes and not CC Mode.  It is a
> confusing mess for users who wish to use both of these, say for
> comparison.
> 
>> Perhaps your personal customization for auto-mode-alist had been
>> shielding you from the original issue. You can add a similar entry to
>> major-mode-remap-alist.
> 
> Not sure what "original issue" you're referring to.  My customisation
> for auto-mode-alist is an eval-after-load for c-ts-mode which deletes
> the *-ts- entries from auto-mode-alist.  This has worked fine until
> recently and should be restored to working again.

Naturally, this only works while auto-mode-alist remains the last source 
of truth regarding the mapping.

> All this confusion in auto-mode-alist, and the horrible workarounds of
> major-mode-remp_\(alist\|defaults\) result from a fundamental conceptual
> error, namely changing c-mode and friends from having specific meanings
> to being vague generic symbols.  THIS is what I should have been
> consulted about, as the owner of these symbols.

I agree that the terminology might be confusing. We've had a discussion 
regarding adding the notion of "languages" to Emacs (I even posted a 
proposal), but so far we decided to go with the "lighter" solution.

> The latest symptom of this misunderstanding, which I bumped into
> yesterday, is that Emacs changes the major mode of a C buffer with M-x
> revert-buffer.  This is clearly unacceptable.

And that started happening since commit 6b2f85caa6, you can look for the 
related discussions and the objections that were voiced at the time.