sub eq{ print "@_"; $_[0] eq $_[1] };;

print eq( $x=1, $x=2 );;
Ambiguous call resolved as CORE::eq(), qualify as such or use & at (eval 13) line 1, <STDIN> line 5.
Use of uninitialized value $_ in print at (eval 13) line 1, <STDIN> line 5.

print &eq( $x=1, $x=2 );;
2 2
1