bug#70958: 30.0.50; eglot-managed-mode hooks not called on shutdown

[Troy Brown <brownts@troybrown.dev>]

On Mon, May 27, 2024 at 10:09 AM João Távora <joaotavora@gmail.com> wrote:
>
> Bugs are only "legitimate" when they are harming someone somewhere.
> This hook has been there for a number of years, and noone has complained
> that I can remember. If you have a use for the on-shutdown, then it's
> a bug.  It'd help to know about this use case. If you don't have a use,
> it's just a doc bug, and patches welcome.
>

The use case is that I was experimenting with updating the
buffer-local indent-region-function (and indirectly
indent-line-function) to be based on eglot-format when the buffer was
connected to the language server.  I was attempting to use the
eglot-managed-mode-hook so I could update these variables when the
Eglot buffer management changed.  Since the hook wasn't being called
on shutdown it would still attempt to call eglot-format when it was no
longer managing the buffer.  The workaround was to use a mode-specific
function for indent-region-function and then having that call
eglot-managed-p to determine if it should call eglot-format or
something else (e.g., indent-relative).