Re: Versioned Tree-sitter parser libraries

[Eli Zaretskii <eliz@gnu.org>]

> From: Yuan Fu <casouri@gmail.com>
> Date: Sun, 16 Apr 2023 20:03:50 -0700
> Cc: Peter Oliver <p.d.oliver@mavit.org.uk>,
>  emacs-devel@gnu.org
> 
> > If we were to load a versioned shared library, how would Emacs know
> > which version to load?
> 
> Another thing is that tree-sitter grammars don’t really have versions (API or ABI versions), except for a tree-sitter version.

AFAIR, there is an ABI version, and we even expose it to Lisp, no?

> >> The background to this question is that I’m thinking about packaging Tree-sitter parsers as RPMs for Fedora (https://pagure.io/tree-sitter-json/blob/rawhide/f/tree-sitter-json.spec).  Typical Fedora practice (https://docs.fedoraproject.org/en-US/packaging-guidelines/#_devel_packages) is to assume that the unversioned symlink isn’t required for regular use, and to place it in a …-devel subpackage that wouldn’t usually be installed.
> > 
> > That practice is fine for when a program is linked against the
> > library, because the -lFOO linker switch is supposed to take care of
> > that, and Emacs doesn't need to know which version is being used.  But
> > here we load the shared libraries at run time, so we must know their
> > names.  These names are explicitly mentioned in the Emacs sources.
> 
> 
> Since Emacs requests/hopes the package manager or the system will provide the grammars, it seems a good idea to support the common way libraries tend to be named. Even maybe just a additional look up for only xxx.0.0, since grammars don’t have ABI versions, at least for now.

I don't think I understand what you suggest in practical terms.  What
does it mean "additional look up for only xxx.0.0"? and why only
xxx.0.0?