BP_Attachment::sanitize_utf8_filename( string $retval )

	public function sanitize_utf8_filename( $retval ) {
		// PHP 5.4+ or with PECL intl 2.0+
		if ( function_exists( 'transliterator_transliterate' ) && seems_utf8( $retval ) ) {
			$retval = transliterator_transliterate( 'Any-Latin; Latin-ASCII; [\u0080-\u7fff] remove', $retval );

		// Older.
		} else {
			// Use WP's built-in function to convert accents to their ASCII equivalent.
			$retval = remove_accents( $retval );

			// Still here? use iconv().
			if ( function_exists( 'iconv' ) && seems_utf8( $retval ) ) {
				$retval = iconv( 'UTF-8', 'ASCII//TRANSLIT//IGNORE', $retval );
			}
		}

		return $retval;
	}