Issue

PHPStan has started complaining for PHP 8.x when the first argument to ob_start ($callback) is null. See https://phpstan.org/r/1164573f-22b3-41fd-a678-bdd27058615b It reports:

Parameter #1 $callback of function ob_start expects callable(): mixed, null given.

However, the documentation for ob_start on 23 June 2022 has:

• a function signature with the first argument accepting null,
• text that says that "The callback parameter may be bypassed by passing a null value"; and
• an example with null as the first argument.

So, unless the documentation is out of date, this looks to be a regression in the ob_start function signature, most likely relating to changes in the way callables are handled in PHP 8.x.

Reproducing

Use the second example from the ob_start documentation, a one-liner:

ob_start(null, 0, PHP_OUTPUT_HANDLER_STDFLAGS ^ PHP_OUTPUT_HANDLER_REMOVABLE);

Implemented at https://phpstan.org/r/1164573f-22b3-41fd-a678-bdd27058615b

Expected output: PHPStan should not report any errors.

Other

We're working on PHP 8.x support for our PHP code base. PHPStan is proving to be a valuable tool. Not sure how we managed to get by without it before. Thanks.