Re: Difficulty building tree-sitter grammars [was: Help sought from C++ expert: ....]

[Alan Mackenzie]

Hello, Eli.

On Thu, Jan 19, 2023 at 19:53:58 +0200, Eli Zaretskii wrote:
> > Date: Thu, 19 Jan 2023 17:14:43 +0000
> > Cc: emacs-devel@gnu.org
> > From: Alan Mackenzie <acm@muc.de>

> > > > Just as a matter of interest, in c++-ts-mode a treesit-query-error gets
> > > > thrown.

> > > I don't see any such error.  Maybe this is again your outdated grammar
> > > library?

> > Heh!  Maybe you're right.  So time to get around to installing one from
> > github.  So I look at the Emacs-29 NEWS for instructions on how to do
> > this.  These instructions are glib and insufficiently helpful.

> Nothing is ever good enough, eh?

Emacs isn't good enough.  That's why we're continually working on it.
;-)

[ .... ]

> If you don't know how to do this given what's in NEWS, then I'm sorry,
> but these instructions are not for you.  You will have to wait until
> someone else (your distro?) produces the grammar library and lets you
> download and install it like you download and install all the image
> libraries and the rest of the optional stuff for Emacs.

> I'm not going to make NEWS a step-by-step tutorial for how to compile
> a bunch of files into a shared library.  That is too much to expect
> from us.  It is NOT our job to teach people how to do that.

Believe it or not, I've never built a shared library in my life (aside
from invoking makefiles) and I'm sure I'm far from being alone.

> > (iv) Then we have precise instructions on where to put the newly built
> > ..so file.  This is good!

> This is the only part that is specific to Emacs, so I deliberately
> included there all the details, since you are unlikely to find it
> elsewhere.

> > This process has so far taken me over an hour, which is too long for
> > something which should be purely routine.  It is likely to take a
> > typical Emacs user even longer.

> Typical Emacs users who don't know how to build libraries from sources
> will need someone else to do the job for them.  Exactly like they do
> with GMP or librsvg or HarfBuzz or any other library that Emacs can
> link against.  Eventually, there's no way around this.

These libraries come with makefiles, so there is no need to get into the
details of how to build them.

> > I suggest that these instructions in NEWS should be enhanced with (i)
> > Tips on downloading stuff from github; (ii) A sample command line for
> > compiling the C/C++ source files; (iii) A sample command line for
> > linking these to the needed .so file.  Possibly two or three versions of
> > these would be needed for the different environments Emacs runs in.

> Sorry, but NO!!

At Dmitry pointed out, it turns out there's a makefile-equivalent for
these grammar libraries, namely treesit-install-language-grammar.  This
worked well for me.

Why is it not mentioned first in NEWS, something like "Typically you can
build and install a grammar with ....." followed by "To build a grammar
outside of Emacs ..." and the description of compiling linking and so on?
Then I would have seen it, and the noise of this thread would have been
avoided.  Again, I doubt I'm the only user who'll not see past the end of
a first unconditional instruction.

-- 
Alan Mackenzie (Nuremberg, Germany).