$ touch test;  # create the dummy

$ perl -Mstrict -Wle 'undef $!; open my $fh, "<", "test" or warn "warn : $!"; print "after : $!"'
after : Inappropriate ioctl for device

$ rm test;

$perl -Mstrict -Wle 'undef $!; open my $fh, "<", "test" or warn "warn : $!"; print "after : $!"
warn : No such file or directory at -e line 1.
after : No such file or directory