push @a;
It is syntax which will compile, but it does generate a warning. Can you show an example of where this would be used? 
use strict;
use warnings;
use diagnostics;
use Data::Dumper;

my @a = 1..3;
push @a;
print Dumper(\@a);

__END__
% ./728108.pl
Useless use of push with no values at ./728108.pl line 9 (#1)
    (W syntax) You used the push() or unshift() function with no argum
+ents
    apart from the array, like push(@x) or unshift(@foo). That won't
    usually have any effect on the array, so is completely useless. It
+'s
    possible in principle that push(@tied_array) could have some effec
+t
    if the array is tied to a class which implements a PUSH method. If
+ so,
    you can write it as push(@tied_array,()) to avoid this warning.

$VAR1 = [
          1,
          2,
          3
        ];

[download]

In reply to Re^3: why does push not default to $_? by toolic
in thread why does push not default to $_? by LanX

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