What's the point of E_ALL | E_STRICT if it's the same value as E_ALL?

Question

• E_ALL equals 8191 (0001 1111 1111 1111)
• E_STRICT equals 2048 (0000 1000 0000 0000)

Using bitwise OR to combine them:

1 1111 1111 1111
  1000 0000 0000

We get the exact same value as the original E_ALL:

1 1111 1111 1111

What's the point of doing error_reporting(E_ALL | E_STRICT) if we can simply do error_reporting(E_ALL) to get the same thing?

Answer 1

The bit values provided in the question are not generally wrong but only for PHP versions older than 5.4.

PHP 5.4+

E_ALL includes E_STRICT so you should use: error_reporting(E_ALL);

Binary                  Name       Decimal
0001 1111 1111 1111     E_ALL      32767
0000 1000 0000 0000     E_STRICT   2048
----------------------------------------------------------------------
0001 1111 1111 1111     E_ALL | E_STRICT produces the same result as E_ALL

PHP 5.3

E_ALL does not include E_STRICT so you should use: error_reporting(E_ALL | E_STRICT);

Binary                  Name       Decimal
0111 0111 1111 1111     E_ALL      30719
0000 1000 0000 0000     E_STRICT   2048
----------------------------------------------------------------------
0111 1111 1111 1111     E_ALL | E_STRICT produces a different value than E_ALL

PHP 5.0 till 5.2

E_ALL does not include E_STRICT so you should use: error_reporting(E_ALL | E_STRICT); but the bit values differ from the values in PHP 5.3.

PHP before 5.0

E_STRICT does not exist so you must use: error_reporting(E_ALL);

Answer 2

You want:

error_reporting(E_ALL | E_STRICT);

E_ALL does not include E_STRICT (unless you are using PHP 5.4+). Your values are incorrect. From Predefined Constants E_ALL is defined as:

All errors and warnings, as supported, except of level E_STRICT prior to PHP 5.4.

32767 in PHP 5.4.x, 30719 in PHP 5.3.x, 6143 in PHP 5.2.x, 2047 previously

Answer 3

1 | 1 = 1

The simplest answer possible is that there's presently no reason to combine the two with a bitwise or operation, but if they ever decide to change those constants in the future, then there might be.

Edit: and you seem to have pulled the wrong values for those constants, making the entire question moot.