#!/usr/bin/perl -w
use strict;

exit main( @ARGV );

{
    my $sub;
    ## BEGIN {
        $sub= sub {
            warn "Called local sub: @_\n";
        };
    ## }
    sub GlobalRoutine {
        &$sub( "Test" );
    }
}

sub main {
    GlobalRoutine("hi");
    return 0;
}
__END__
This produces the following:
Use of uninitialized value in subroutine entry at localsub.pl line 14.
Can't use string ("") as a subroutine ref while "strict refs" in use at localsub.pl line 14.