>perl -wMstrict -MO=Deparse,-p -le
"my $x = 5;
 $x = $x + ++$x + $x++;
 warn $x;
"
BEGIN { $^W = 1; }
BEGIN { $/ = "\n"; $\ = "\n"; }
use strict 'refs';
(my $x = 5);
($x = (($x + (++$x)) + ($x++)));
warn($x);
-e syntax OK

>perl -wMstrict -le
"my $x = 5;
 $x = $x + ++$x + $x++;
 warn $x;
"
18 at -e line 1.