bug#55278: 29.0.50; OSM package

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Cc: 55278@debbugs.gnu.org
> Date: Fri, 06 May 2022 19:19:32 -0400
> 
>   > No, it's implemented in json.c in the Emacs sources.  But to have that
>   > function defined, you need to build Emacs with libjansson, which is an
>   > optional dependency of Emacs.
> 
> That is strange.  If the function json-parse-string is defined in the
> Emacs sources, why compile it only if something else is enabled?

Because the actual implementation is in the libjansson library; the
Emacs sources only wrap that by a glue to allow use to use JSON with
Emacs Lisp objects.

> Does OSM depend on anything about jansson other than json-parse-string?
> What does jansson do?

The library implements most of JSON handling.