$ perl -v | head -2 | tail -1
This is perl 5, version 34, subversion 0 (v5.34.0) built for cygwin-thread-multi

$ perl -E 'say 1~~2 ? "yes" : "no"'
Smartmatch is experimental at -e line 1.
no

$ perl -E 'my $x = 1; given ($x) { when (2) { say "yes" } default { say "no" } }'
given is experimental at -e line 1.
when is experimental at -e line 1.
no