Assignment within is_null() not taken into account.

[pauljherring]

Bug report

Variable assignment within is_null() doesn't take into account the result of that is_null()

Code snippet that reproduces the problem

https://phpstan.org/r/a158f7de-7672-4860-a430-4beb421ae544

<?php declare(strict_types = 1);

/**
* @return array<mixed>|null
*/
function foo(){
	if (rand()<.5){
		return [1,2,3];
	}
	return null;
}

if (!is_null($c = foo())){
	echo count($c); // line 14
}

Output

14 | Parameter #1 $value of function count expects array\|Countable, array\|null given.

Expected output

No Errors!

[phpstan-bot]

@pauljherring After the latest commit in dev-master, PHPStan now reports different result with your code snippet:

@@ @@
-PHP 8.0 (1 error)
-==========
-
-14: Parameter #1 $value of function count expects array|Countable, array|null given.
-
-PHP 7.1 – 7.4 (1 error)
-==========
-
-14: Parameter #1 $var of function count expects array|Countable, array|null given.
+No errors

[ondrejmirtes]

Fixed: phpstan/phpstan-src@b2bf703

[github-actions]

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