This always works for me:
ini_set('display_errors', 1); ini_set('display_startup_errors', 1); error_reporting(E_ALL);
However, this doesn't make PHP to show parse errors - the only way to show those errors is to modify your php.ini with this line:
display_errors = on
via http://stackoverflow.com/questions/1053424/how-do-i-get-php-errors-to-display