#!perl -w
use warnings;
use strict;
use CGI;
print "$] $CGI::VERSION\n";

sub Foo::get_end_date { return undef }
my $pa = bless {}, 'Foo';

print CGI->new->textfield(-name=>"end_date",
	-default=>substr($pa->get_end_date(),0,10)), "\n";

__END__

5.026000 4.36
Use of uninitialized value in subroutine exit at .../CGI.pm line 472.
<input type="text" name="end_date"  />

##</code><code>##

$ perl -wle 'sub x{@_} print x(substr undef,0)'