sub func {
  local $_;   # THIS IS THE KEY LINE YOU NEEDED
  open(READ, "< test.txt");
  while(<READ>) {
    #   print;
  }
  close READ;
  return;
}

# outputs the final line w/o a problem
Files: ree ree1 ree2
$VAR1 = [
          'ree',
          'ree1',
          'ree2'
        ];
The file is ree
The file is ree1
The file is ree2
Files: ree ree1 ree2