WordPress at a glance
filter is not described

wp_query_search_exclusion_prefix filter-hook . WP 4.7.0

Filters the prefix that indicates that a search term should be excluded from results.

Usage

add_filter( 'wp_query_search_exclusion_prefix', 'filter_function_name_4333' );
function filter_function_name_4333( $exclusion_prefix ){
	// filter...

	return $exclusion_prefix;
}
$exclusion_prefix(string)
The prefix. Returning an empty value disables exclusions.
Default: '-'

Where the hook is called

WP_Query::parse_search()
wp-includes/class-wp-query.php 1286
$exclusion_prefix = apply_filters( 'wp_query_search_exclusion_prefix', '-' );

Where the hook is used (in WP core)

Does not used.