bug#34525: replace-regexp missing some matches

[Alan Mackenzie]

Hello, Eli.

On Mon, Feb 25, 2019 at 22:11:57 +0200, Eli Zaretskii wrote:
> > Date: Sun, 24 Feb 2019 21:00:58 +0000
> > Cc: daniel.lopez999@gmail.com, 34525@debbugs.gnu.org, 
> > monnier@iro.umontreal.ca
> > From: Alan Mackenzie <acm@muc.de>

> > > > Sadly, UPDATE_SYNTAX_TABLE sets its internal structure gl_state not for
> > > > the current contents of position 1948, but the contents of 1948 before
> > > > the change at the top of the buffer (Bitmap -> SharedBitmap) was made.
> > > > So it picks up the syntax for the "<" rather than the "B".

> > > Are you saying that we've modified buffer text, but
> > > re_match_2_internal still holds to a C pointer to buffer text before
> > > the change?

> > I don't think that's the case.  The relevant buffer pointers/sizes are
> > calculated (in search_buffer_re) as

> >     p1 = BEGV_ADDR;
> >     s1 = GPT_BYTE - BEGV_BYTE;
> >     p2 = GAP_END_ADDR;
> >     s2 = ZV_BYTE - GPT_BYTE;

> > each time before a search.

> So you are saying that gl_state uses a stale offset, which should have
> been updated due to the previous replacements?

That's what I think is happening, yes.  I need to gather more evidence,
though.

I've spent a lot of today fighting git and 2-year-old Emacs's build
systems trying to bisect the repository to find what introduced the bug.

-- 
Alan Mackenzie (Nuremberg, Germany).