It took some major hunting, but I managed to find it in my_theme/custom/inc/eys-custom-types.php, nowhere near anywhere I expected to find it, like functions.php or custom_functions.php
So this is the actual call:
function eys_connection_types() {
if ( !function_exists('p2p_register_connection_type') )
return;
p2p_register_connection_type( 'serials', 'writers' );
p2p_register_connection_type( 'post', 'writers' );
}
add_action('init', 'eys_connection_types', 100);
I discovered the Shopp plugin had also recently been updated, and upon deactivation, was greeted with this:
Backtrace from warning 'Connection types without a 'name' parameter are deprecated.' at /home/eys/public_html/wp-content/plugins/posts-to-posts/core/type-factory.php 42:
/home/eys/public_html/wp-content/plugins/posts-to-posts/core/type-factory.php 42 calling trigger_error()
/home/eys/public_html/wp-content/plugins/posts-to-posts/core/api.php 80 calling register()
/home/eys/public_html/wp-content/themes/eys_182/custom/inc/eys-custom-types.php 171 calling p2p_register_connection_type()
calling eys_connection_types()
/home/eys/public_html/wp-includes/plugin.php 403 calling call_user_func_array()
/home/eys/public_html/wp-settings.php 303 calling do_action()
/home/eys/public_html/wp-config.php 93 calling require_once()
/home/eys/public_html/wp-load.php 29 calling require_once()
/home/eys/public_html/wp-blog-header.php 12 calling require_once()
/home/eys/public_html/index.php 17 calling require()
Backtrace from warning 'Connection types without a 'name' parameter are deprecated.' at /home/eys/public_html/wp-content/plugins/posts-to-posts/core/type-factory.php 42:
/home/eys/public_html/wp-content/plugins/posts-to-posts/core/type-factory.php 42 calling trigger_error()
/home/eys/public_html/wp-content/plugins/posts-to-posts/core/api.php 80 calling register()
/home/eys/public_html/wp-content/themes/eys_182/custom/inc/eys-custom-types.php 172 calling p2p_register_connection_type()
calling eys_connection_types()
/home/eys/public_html/wp-includes/plugin.php 403 calling call_user_func_array()
/home/eys/public_html/wp-settings.php 303 calling do_action()
/home/eys/public_html/wp-config.php 93 calling require_once()
/home/eys/public_html/wp-load.php 29 calling require_once()
/home/eys/public_html/wp-blog-header.php 12 calling require_once()
/home/eys/public_html/index.php 17 calling require()
on top of my website (which I'm assuming is from the backtrace). Does that help?