Mupen64Plus supports a single data directory and a single plugin directory in
its configuration, yet we need data and plugin files from a variety of
packages.  The best way to deal with this is to install all packages from
which data and plugin files are needed into one's profile, and point the
configuration there.  Hence, the ui-console package provides propagated inputs
for packages with the most important data and plugin files, and this patch
provides the user instructions on what needs to be done in order to have
Mupen64Plus find the relevant data and plugins.

--- a/src/plugin.c
+++ b/src/plugin.c
@@ -122,6 +122,22 @@ m64p_error PluginSearchLoad(m64p_handle ConfigUI)
     {
         const char *plugindir = (*ConfigGetParamString)(ConfigUI, "PluginDir");
         lib_filelist = osal_library_search(plugindir);
+        /* Guix specific */
+        if (lib_filelist == NULL)
+        {
+            DebugMessage(M64MSG_ERROR, "No plugins found in PluginDir path: %s", plugindir);
+            DebugMessage(M64MSG_ERROR,
+                         "\n\n"
+                         "*********************************\n"
+                         "*** Notice for GNU Guix users ***\n"
+                         "*********************************\n"
+                         "\n"
+                         "You might want to edit your mupen64plus.cfg (in $XDG_CONFIG_HOME by default)\n"
+                         "and set SharedDataPath to /path/to/my_guix_profile/share/mupen64plus and\n"
+                         "PluginDir to /path/to/my_guix_profile/lib/mupen64plus so that data and plugins\n"
+                         "are found.\n"
+                         "\n");
+        }
     }
 
     /* if still no plugins found, search some common system folders */
ption value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=7c2013dcc9acc7dec5152e0efd8d4eb143ce31b1'>root</a>/<a href='/guix/log/etc?id=7c2013dcc9acc7dec5152e0efd8d4eb143ce31b1'>etc</a>/<a href='/guix/log/etc/substitutes?id=7c2013dcc9acc7dec5152e0efd8d4eb143ce31b1'>substitutes</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/etc/substitutes?id=7c2013dcc9acc7dec5152e0efd8d4eb143ce31b1&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-06-07 11:31:17 +0100'>2021-06-07</span></td><td><a href='/guix/commit/etc/substitutes?id=26499816a973b3aab9aaf8e13b909d0bde4e2dd5'>etc: Add "bordeaux.guix.gnu.org.pub" public key file.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/substitutes/bordeaux.guix.gnu.org.pub: New file.
* Makefile.am (dist_pkgdata_DATA): Add it.
* guix/self.scm (miscellaneous-files): Add
"share/guix/bordeaux.guix.gnu.org.pub".
</span></span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2020-07-10 00:11:00 +0200'>2020-07-10</span></td><td><a href='/guix/commit/etc/substitutes?id=d283bb960f927dd5f7bb8b96bc697221e4e8ad39'>maint: Remove traces of "berlin.guixsd.org".</a><span class='msg-avail'>...<span class='msg-tooltip'>The guixsd.org domain is no longer advertised since before in 1.0.0
release in May 2019.

* etc/substitutes/berlin.guixsd.org.pub: Rename to...
* etc/substitutes/berlin.guix.gnu.org.pub: ... this.
* etc/substitutes/ci.guix.gnu.org.pub,
etc/substitutes/ci.guix.info.pub: Adjust accordingly.
* gnu/services/base.scm (%default-authorized-guix-keys): Likewise.
* guix/build/download-nar.scm (urls-for-item): Likewise.
* guix/self.scm (miscellaneous-files): Likewise.
* Makefile.am (dist_pkgdata_DATA): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-06-29 14:27:22 +0200'>2019-06-29</span></td><td><a href='/guix/commit/etc/substitutes?id=3a8bfebed94ba295432da8304b7ffb4a611ef761'>etc: Remove hydra.gnu.org.pub key.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/substitutes/hydra.gnu.org.pub: Delete file.
* guix/self.scm (miscellaneous-files): Don't install it.
* Makefile.am (dist_pkgdata_DATA): Remove it.
* gnu/services/base.scm (%default-authorized-guix-keys): Likewise.
(hydra-key-authorization): Rename to…
(substitute-key-authorization): …this.  Adjust only call site.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>