my @a = x() | (4,5,6);

##</code><code>##

my @a = scalar(x()) | scalar(4,5,6);

##</code><code>##

    my @a = scalar(x()) | scalar(4,5,6);
=== my @a = scalar(x()) | scalar(5,6);
=== my @a = scalar(x()) | scalar(6);
=== my @a = scalar(x()) | 6;

##</code><code>##

>perl -MO=Deparse -e"my @a = x() | (4,5,6);"
my(@a) = x() | ('???', '???', 6);