Re: A proposal for the future of open-paren-in-column-0-is-defun-start.

[Stefan Monnier <monnier@iro.umontreal.ca>]

> In that case, we could arrange for open-paren-in-column-0-is-defun-start
> to be heeded _along with_ comment-use-syntax-ppss.

Be my guest.  But before accepting such code, I'll want to see some
concrete evidence that it has a real benefit.

So far, all concrete evidence we have has no direct connection to
open-parens-in-column-0 (other than some people's gut feelings).

We should treat this performance problem the same as any other: do the
profiling, look into the code that takes the major part of the time,
look into why it takes so much time, ...

So far we have: scrolling is too slow in some C buffer and the profile
indicates it happens "somewhere in jit-lock".  There's a lot that might
be going on "in jit-lock", so we've barely scratched the surface of
the problem.

My gut feeling is that we're going to find that we're not spending much
of that time in `back_comment` (the C function which used this
open-paren-in-column-0 heuristic).  This seems to be confirmed by the
fact that setting comment-use-syntax-ppss to nil made no difference: the
problem is elsewhere and we're just wasting time discussing this old
heuristic whose time has passed.


        Stefan