bug#71823: 31.0.50; project-mode-line and eglot duplicate project-name in mode-line

[Spencer Baugh <sbaugh@janestreet.com>]

João Távora <joaotavora@gmail.com> writes:

> On Wed, Jul 3, 2024 at 2:17 PM Spencer Baugh <sbaugh@janestreet.com> wrote:
>>
>> João Távora <joaotavora@gmail.com> writes:
>>
>> > On Sun, Jun 30, 2024, 13:51 <sbaugh@catern.com> wrote:
>> >
>> >  João Távora <joaotavora@gmail.com> writes:
>> >  > On Sat, Jun 29, 2024, 15:24 Spencer Baugh <sbaugh@janestreet.com> wrote:
>> >  >
>> >  >  Or, here's an alternative idea, more aggressive:
>> >  >
>> >  >  What if Eglot just sets project-mode-line=t in eglot-managed buffers, and removes the project-name from the Eglot entry
>> >  >  entirely?
>> >  >
>> >  >  Then the language identifier would be the major mode, the project identifier would be project-mode-line, and the eglot
>> >  status
>> >  >  indicator would just be for the status of the server.
>> >  >
>> >  > Works for me, it's in line with Eglot's policy of setting other modes when managing buffers. Show a patch.
>> >
>> >  Attached.
>> >
>> >  I do think this is a great way to resolve this - now that
>> >  project-mode-line exists, using it deletes one small bit of
>> >  eglot-specific functionality, which is in line with the Eglot design
>> >  philosophy.
>> >
>> > Yes.
>> >
>> >  The only issue is that this was only added to mode-line-format in Emacs
>> >  30, so we can only use it in Emacs 30 or later.
>> >
>> > No, that's not an issue, or rather your solution isn't the way to solve it. In trunk Eglot use everything that is in trunk Emacs. In
>> > released Eglot versions name sure you depend on capable versions of core GNU Elpa packages, a set which already includes
>> > project.el. So basically version bumps solves it.
>>
>> Yes, certainly.  That's why I bumped the required version of project.el
>> in the Package-Requires.
>>
>> But, loading a newer version of project.el doesn't add the
>> project-mode-line entry to mode-line-format.  That's done in
>> bindings.el, and can't be updated.  So we still need to do something
>> else to accomodate an Emacs 29 user with an updated eglot.el and
>> project.el.
>
> Hmm, I don't like it I must say.  I thought there would be some kind
> of project-mode-line-mode to call that would do what it has to do
> to put the project in the mode-line.  Like this it feels too hacky
> and intrusive into project.el's and binding.el's implementation.

Sure, so here are some possible solutions:

A. Check (member '(project-mode-line project-mode-line-format) mode-line-format)
B. Check (version<= "30" emacs-version)
C. project.el itself could ensure, when loaded, that mode-line-format
   contains project-mode-line.  eglot itself does this with
   eglot--mode-line-format, running the following at load time:
   
     (add-to-list 'mode-line-misc-info
                `(eglot--managed-mode (" [" eglot--mode-line-format "] ")))
D. Add a project-minor-mode like you suggest which puts the project in
   the mode-line.

Do any of these seem acceptable?

I personally prefer C.

> I also don't understand the other changes (i.e. to the menu) but
> that's OK.

The project-name in the eglot mode line entry had the server menu
attached to it.  Since the project-name is no longer present, the server
menu isn't accessible.  To make the server menu accessible again, it's
added to the main eglot menu.

> I'm going back to my previous recommendation of redesigning Eglot's
> eglot--mode-line-format into eglot-mode-line-format in the likeness of
> other packages (Flymake for example).  If I'm going to carefully
> review and test changes to Eglot's mode-line machinery like the ones
> you are presenting here, it might as well be the most useful changes
> possible.
>
> That change should fix this and other problems.  Until then, I don't think
> this is an extremely serious problem.

Making eglot-mode-line-format customizable is an orthogonal change,
which gives different benefits.

To be clear, the problem I want to fix is "there's two mode-line entries
(project-mode-line-format, eglot--mode-line-format) which include
project-name, so project-name shows up twice".

Yes, making those entries customizable allows the user to solve the
problem by customizing the entries.

But I don't want to delegate the responsibility of solving this problem
to the user, I want the problem to just be gone: the entries should just
not duplicate project-name.