bug#60565: [PATCH] src/pgtkfns.c (parse_resource_key): Use recursive schema lookup

[Eli Zaretskii <eliz@gnu.org>]

> From: Tad Fisher <tadfisher@gmail.com>
> Date: Thu, 5 Jan 2023 01:58:47 +0000
> 
> 
> From 8e2cf80593dd78030929f96f0f1a3e1a325428a4 Mon Sep 17 00:00:00 2001
> From: Tad Fisher <tadfisher@gmail.com>
> Date: Wed, 4 Jan 2023 13:40:17 -0800
> Subject: [PATCH] ; * src/pgtkfns.c (parse_resource_key): Use recursive schema lookup
> 
> XDG_DATA_DIRS may consist of multiple directories, and
> g_settings_schema_source_get_default composes these into a recursive
> schema source. One must pass TRUE to g_settings_schema_source_lookup,
> otherwise only the first directory in XDG_DATA_DIRS is searched.
> 
> It follows that in the case that the directory containing the compiled
> GSettings schema for Emacs is not the first in XDG_DATA_DIRS,
> parse_resource_key will not accept any resource key, which causes
> pgtk_get_defaults_value and pgtk_set_defaults_value to fail.
> 
> This impacts systems that compose multiple GSettings schema sources
> via XDG_DATA_DIRS, such Flatpak and NixOS.
> 
> Supporting GIO documentation for g_settings_schema_source_get_default:
> 
> > The returned source may actually consist of multiple schema sources
> > from different directories, depending on which directories were given
> > in `XDG_DATA_DIRS` and `GSETTINGS_SCHEMA_DIR`. For this reason, all
> > lookups performed against the default source should probably be done
> > recursively.

Thanks.  Po Lu, any comments?