Add support for constructor assertions

[axlon]

Enables the following:

class Person
{
    /** @phpstan-assert non-empty-string $firstName */
    public function __construct(string $firstName) {}
}

$person = new Person($firstName);
// $firstName can no longer be empty

Fixes phpstan/phpstan#10645 (partially)

[phpstan-bot]

You've opened the pull request against the latest branch 1.11.x. If your code is relevant on 1.10.x and you want it to be released sooner, please rebase your pull request and change its target to 1.10.x.

[ondrejmirtes]

What do you mean by "partially"?

[ondrejmirtes]

Move this into anonymous function and use a string parameter coming into the function.

[axlon]

What do you mean by "partially"?

@ondrejmirtes This PR currently does not tackle assertions on promoted properties, so for example:

class Person
{
    /** @phpstan-assert non-empty-string $this->firstName */
    public function __construct(public string $firstName) {}
}

$person = new Person($firstName);
dumpType($person->firstName); // non-empty-string

I'm working on this as well but it needs a little more time

[ondrejmirtes]

This use case does not make sense to me, you can type the property to be non-empty-string from the start, no need to assert it.

[axlon]

The use case is being able to annotate promoted props to be a narrowed version of the variable going in. I skipped some statements in my original example for brevity but there was supposed to be an assert call in the constructor asserting the promoted prop was not empty.

Essential this, but with promoted props:

class Person
{
    /**
     * @var non-empty-string
     */
    public string $firstName;

    public function __construct(string $firstName)
    {
        assert($firstName !== '');
        $this->firstName = $firstName;
    }
}

I am aware I could also annotate the class with @property as well, so its not really a big deal if asserting $this->firstName from a constructor is a no go 👍

[ondrejmirtes]

Thank you!