I've reported it to vue-mode, but vue-mode is a thin wrapper around
mmm-mode (mode for multiple major modes in the same buffer). It may be hard
for the mmm-mode maintainer to understand my issue since I'm using a
derived mode, not mmm-mode directly.
I was hoping Stefan Monnier might chime in with some ideas -- I think I'll
have to dive into it, and I'm OK with that, but could use a bit of
guidance. I suspect it's related to the fact that mmm-mode is switching
major modes within the same buffer and trying to adjust everything on the
fly, even when the buffer hasn't changed. (In mmm-mode it switches modes
when you enter a certain region of the file.)

For instance is there any way to temporarily completely turn off the
syntax-ppss caching mechanism, so I can really see if that's the root cause?

I can definitely confirm that holding everything else constant except that
single emacs commit of Stefan's, 0b3982b1a38, triggers the failure. But I
understand it's probably some interaction between that and mmm-mode.


On Tue, Oct 15, 2019 at 2:28 AM Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Gary Oberbrunner <garyo@oberbrunner.com>
> > Date: Mon, 14 Oct 2019 18:08:32 -0400
> >
> > I'm using vue-mode, based on mmm-mode with Emacs 27 nightly on Windows
> 10.
> > As of commit 0b3982b1a38, indentation stopped working in vue-mode
> buffers.
>
> Please report that to the developers of vue-mode first, if you didn't
> already.  If they conclude this is a core Emacs problem, and provide
> evidence for that, we will look into this.
>
> Thanks.
>


-- 
Gary