Bug report

After upgrading from 2.1.27 to 2.1.28, PHPStan started to report strange false positives on my projects. Apparently, when comparing the result of a trim($value) operation, the $value variable is narrowed to a string.

function doSomething(mixed $value): void
{
	if (trim($value) === '') {
		return;
	}
	\PHPStan\dumpType($value);
}

Here, PHPStan believes that $value must be a non-empty-string which I believe is wrong. $value could be anything that can be cast to a string, such as an integer or a Stringable object.

Code snippet that reproduces the problem

https://phpstan.org/r/8cbb0de1-d0c3-4c13-bcf5-7cbd1b1fd69a

Expected output

$value should still be mixed.

Did PHPStan help you today? Did it make you happy in any way?

No response