Description:
------------
When we use parse_ini_file function, we can't define a array with name "on"

But we can't find any reference of an reserver-keyword "on" in documentation

Reproduce code:
---------------
myArray[] = "php is good"
myArray[] = "asp is not good"

on[] = "linux"
on[] = "macos X"


print_r(parse_ini_file('file.ini'));

Expected result:
----------------
array(
  [myArray] => Array
    (
      [0] => "php is good"
      [1] => "asp is not good"
    )
   [on] => Array
    (
      [0] => "linux"
      [1] => "macos X"
    )
)

Actual result:
--------------
Warning: Error parsing file.ini on line 41 in index.php on line 2