It looks like you are absolutely right. The output of perl -MO=Deparse,-p a.pl follows (after removing Data::Dumper):

sub mycode {
    (my $var = $_[0]);
    (defined($var) ? print("mycode() called with $var\n") :
print("mycode() called with no operands.\n"));
    ($var and (my $foo = 'blah'));
#^^^^^^^^^^^^^^^ Look here
    ($foo and print("foo is $foo\n"));
    ($foo ||= 'FOO');
}
mycode('test');
mycode();
mycode();
mycode();
a.pl syntax OK

[download]

my $foo = 'blah' is optimized away.

In order to make it behave as expected, my $foo; needs to be its own statement, with no conditional.

Update: Removed bit about strict, see the follow up

In reply to Re: Re: Re: static-like persistence of my variable due to trailing conditional by jsprat
in thread static-like persistence of my variable due to trailing conditional by meonkeys

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