SIGTERM/SIGINT master/slave behavior

Hi. When master server receives smart shutdown request (TERM) does it
exit after making sure it sends all received writes to the slave
server(s), or it exits leaving the slave in an inconsistent state? What
about during fast shutdown (SIGINT)? I know that it asks current
requests to terminate immediately in that case, but what about the
replication connection? Is it safe to send SIGINT when intending to do a
manual failover?

https://www.postgresql.org/docs/10/server-shutdown.html

Thanks.