bug#16526: 24.3.50; scroll-conservatively & c-mode regression

[Alan Mackenzie]

Hi, Eli.

On Sun, Feb 02, 2014 at 08:07:25PM +0200, Eli Zaretskii wrote:
> > Date: Sun, 2 Feb 2014 17:40:50 +0000
> > Cc: martin rudalics <rudalics@gmx.at>, 16526@debbugs.gnu.org
> > From: Alan Mackenzie <acm@muc.de>

> > > Perhaps Alan could explain why the CC Mode fontification takes such a
> > > long time for buffer position 948757.

> > No, sorry I can't explain it.  Except that CC Mode will be scanning
> > forward through the entire buffer once (hopefully only once) to get the
> > "parse state" near EOB.

> Why can't it start from a position outside any function instead?

It used to do this, but this was leading to errors, particularly in C++
where, for example, people frequently write "namespace {" rather than
putting the "{" on the next line in column 0.

Even on xdisp.c, over 30,000 and almost 1Mb, the scan doesn't take that
long - a little over a second on my 4 yo machine.

-- 
Alan Mackenzie (Nuremberg, Germany).