Get rid of the \ in front of call to fix_path (actually even that &, but that's not the problem here), otherwise you stored a ref to a scalar instead of a scalar. In the future, if you can simplify your code to a runnable form, it will help those who are trying to help you.

my $a = &fix_path();
print "source variable AFTER fix_path $a\n";



sub fix_path{
        return "abcd";
}
[download]