Nullability false positive on a complex condition

[janedbal]

Code snippet that reproduces the problem

• https://phpstan.org/r/f62731831f42c04751f358a1a13f2ed8

class HelloWorld
{
	public function sayHello(?int $a, ?int $b): void
	{
		
		if ($a === null && $b === null) {
			throw new \LogicException();
		}
		
		$this->foo($a !== null ? $a : $b); // error: Parameter #1 $c of method HelloWorld::foo() expects int, int|null given.  
	}
	
	public function foo(int $c){}
}

Expected output

• calling foo should be ok

[ondrejmirtes]

Probably the same problem as #966 but I'll leave this open for referring to this specific case.

[muglug]

There are a whole bunch of similar logic tests in TypeAlgebraTest. Most, if not all, fail in PHPStan but I imagine it's not that hard to alter your engine for them to pass.

Psalm doesn't deal with #966 well either, as its algebraic assertions don't cover comparisons between variables.

[ondrejmirtes]

I misread the example - this is more complex than #966 (#966 does not work because I broke something on dev-master, it works on 0.9.2). This will require something I now call "Dependent types". Because of their lack, PHPStan can't solve these examples either:

• https://phpstan.org/r/15fded5eb0bae628c125eaef298bbb64 (the variable can be only foofoo or barbar)
• https://phpstan.org/r/ee09f665ed025b91c0a952c883681436 (variable definitely exists)

Therefore I'm postponing solving this to after the next release because it's a bigger topic.

[muglug]

Yeah, supporting this is on an ongoing basis is non-trivial. It requires keeping track of the assertions made in previous expressions as well as current types. A year-old description of that process is here: https://medium.com/vimeo-engineering-blog/automated-type-inference-for-dynamically-typed-programs-6e79197e5420

[ondrejmirtes]

Similar example https://phpstan.org/r/87a4b338-f3bb-466f-b1fc-cbd5eecc00b5

[janedbal]

Seems like it works on latest version https://phpstan.org/r/622c3f59-0fd7-4442-b89e-356e25287fd6

[ondrejmirtes]

@janedbal It doesn't, it just moved to level 8: https://phpstan.org/r/9cc9771c-0c03-412c-b186-7f99bac5120f

[phpstan-bot]

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

@@ @@
-29: Function hello() should return array<string> but returns array<string>|null.
+No errors

[phpstan-bot]

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

@@ @@
-12: Parameter #1 $c of method HelloWorld::foo() expects int, int|null given.
+No errors

[github-actions]

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