Regardless of any contortions Benchmark goes through to execute code in the calling package,
lexical variables are not in any package. It is impossible for code to access lexical variables that are not in scope.
This can be seen with a very simple Benchmark:
#!perl
use Benchmark;
$main::variable = 'global';
my $variable = 'lexical';
timethese(1,
{
anon => sub { print "$variable\n"; },
string => 'print "$variable\n";',
}
);
__END__
Benchmark: timing 1 iterations of anon, string...
lexical
anon: 0 wallclock secs ( 0.00 usr + 0.00 sys = 0.00 CPU)
(warning: too few iterations for a reliable count)
global
string: 0 wallclock secs ( 0.00 usr + 0.00 sys = 0.00 CPU)
(warning: too few iterations for a reliable count)
The anonymous sub snippet accesses the lexical $variable, because the snippet is compiled in the same scope as the lexical variable. The string snippet accesses the global $variable, because the snippet is compiled in a completely separate scope, when the eval is executed.