Re: cc-mode fontification feels random

[Jim Porter]

(Note: re-adding emacs-devel here, since I posted through Gmane and
attempted to eliminate dupe messages by posting only to the Gmane
mirror and not mailing the list directly. That was backwards, and I
should have removed the Gmane mirror, or perhaps just ignored the
issue and let the mailing list handle dupes.)

On Fri, Jun 4, 2021 at 12:18 PM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > Cc: Eli Zaretskii <eliz@gnu.org>, Daniel Colascione <dancol@dancol.org>,
> >  ubolonton@gmail.com
> > From: Jim Porter <jporterbugs@gmail.com>
> > Date: Fri, 4 Jun 2021 09:43:26 -0700
> >
> > On 6/4/2021 3:08 AM, João Távora wrote:
> > > - However, LSP support for fontification seems like it's potentially
> > >    _less_ efficient than integrating something like tree-sitter as a C
> > >    module in Emacs.  That's because the contents of the buffer and
> > >    fontification results are continually transmitted back and forth via
> > >    pipes and JSON format.
> >
> > I imagine these potential performance issues would also be exacerbated
> > by editing over TRAMP.
>
> Why?  Fontification is always local, even if the files you edit are on
> a remote host.

The way I understand this particular hypothetical is that Eglot would
be responsible for asking the LSP server for syntax highlighting and
would then do the necessary work to tell Emacs how to fontify the
buffer. Currently, the way Eglot works for remote files is that it
runs the LSP server on the remote host via TRAMP. That works out
nicely right now, but if we wanted to get the syntax highlighting from
the (remote) LSP server to the (local) Emacs instance, that data would
have to go through TRAMP. I'm not sure how much data we're talking
about here, but if there are performance concerns about doing this
locally via pipes, it would be exacerbated by going through a slow
network.

- Jim