Acording to https://notabug.org/diogo/gnu-social/src/master/plugins/SphinxSearch, you need to install Sphinx server and the sphinx pecl extension for php on the client side. However, https://pecl.php.net/package/sphinx lists as requirement having PHP version 6.0.0 or older.
If there is no way to get a newer extension, maybe the plugin should be removed. It's a pity, I wanted to try it xD
07/02/22 | 02:42:26 diogo: Interesting to have PHP 6 as a requirement when it was never released, it turned out to be PHP 5.6
07/02/22 | 02:50:07 diogo: it's a simple plugin and we can replace that pecl, but as it is a new feature we'll probably only re-add it to v3 now...
(from chat room)
07/02/22 | 02:42:26 diogo: Interesting to have PHP 6 as a requirement when it was never released, it turned out to be PHP 5.6
07/02/22 | 02:50:07 diogo: it's a simple plugin and we can replace that pecl, but as it is a new feature we'll probably only re-add it to v3 now...
Acording to https://notabug.org/diogo/gnu-social/src/master/plugins/SphinxSearch, you need to install Sphinx server and the sphinx pecl extension for php on the client side. However, https://pecl.php.net/package/sphinx lists as requirement having PHP version 6.0.0 or older. If there is no way to get a newer extension, maybe the plugin should be removed. It's a pity, I wanted to try it xD
(from chat room)
07/02/22 | 02:42:26 diogo: Interesting to have PHP 6 as a requirement when it was never released, it turned out to be PHP 5.6
07/02/22 | 02:50:07 diogo: it's a simple plugin and we can replace that pecl, but as it is a new feature we'll probably only re-add it to v3 now...
Thanks for bringing this to an issue!