Re: Bug #22983 (syntax-ppss returns wrong result) is still open. Could we fix it before the release, please.

[Dmitry Gutov]

On 06/11/2016 01:07 PM, Alan Mackenzie wrote:

> > Why before the release in particular?
>
> Haven't I just said?  :-)  If not before the release, then when?

Right after? Slightly after that? Whenever. "Before the release" doesn't 
look like a meaningful constraint, considering the commit will go on master.

I'm still not even clear which branch 25.2 will come from, and that's an 
important concern.

> Is Vitalie still working on ... anything else to do with
> Emacs)?

Yes:

https://github.com/emacs-ess/ESS/commits/master
https://github.com/vspinu/polymode/commits/master

Adding hard-widen, however, is a low-level endeavor, and it seems nobody 
sufficiently proficient there is in any hurry to help.

> I can't say I feel enthusiastic about "hard-widen".  I haven't looked
> into it that thoroughly, but it feels a bit like an ugly hack whose
> ramifications might percolate all the way through Emacs, and that might
> make us regret it fairly heavily in the not too distant future.

Hadn't you yourself proposed a far more invasive solution, not too long 
ago? I think hard-widen strikes a certain balance, in that is will 
require a moderate amount of changes in Emacs, and little to no changes 
in the user code, considering we've always (or at least for a long time) 
had to write it with consideration for the current narrowing.

If there's anything to complain about it, it's that it doesn't bring new 
niceties. So: modest gains, and little amount of pain. Seems 
conservative enough for the Emacs community.

> > > Yes, I think having the binary toggle `syntax-ppss-dont-widen' purely to
> > > direct the innards of the function is poor programming (since it
> > > explicitly toggles a toggle inside a supposedly abstract function).
>
> > Abstract?
>
> Yes, abstract.  `syntax-ppss' has an specification and interface on the
> one side, and an implementation on the other.

Just like any other function?

> > > I think an improvement would be to dispense with that toggle, and
> > > have two distinct functions, one in place of
> > > `syntax-ppss-dont-widen' being nil, and the other in place of
> > > `s-p-d-w' being non-nil.  The latter function might usefully have an
> > > extra parameter specifying the base point that parse-partial-sexp
> > > should be calculated from.  That would leave quite a few options
> > > open for the internal logic of the function.
>
> > That wouldn't help in the multi-mode case, which is the primary use I
> > have in mind for syntax-ppss-dont-widen.
>
> Why would it not help?

Because you (in CC Mode) will choose the more straightforward version 
that does widen. And I, in mmm-mode, will thus have no ability to modify 
what your code is doing by narrowing, and will send you dark thoughts 
instead.

What's the purpose of the other function? Who's going to use it?