Call to method foo() on an unknown class FooBar when FooBar is a trait

[kylekatarnls]

Bug report

Code snippet that reproduces the problem

<?php declare(strict_types = 1);

trait FooBar
{
	public function foo(): string
	{
		return 'abc';
	}
}

class HelloWorld
{
	public function sayHello(mixed $value): void
	{
		if ($value instanceof FooBar) {
			echo $value->foo();
		}
	}
}

https://phpstan.org/r/21864fe8-ba76-4945-b9fc-9dc27e286ca1

Expected output

I expect no error for the code above.

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

This snippet system with try is still very cool to be sure in a blink if current version has the same output.

[canvural]

But this code cannot really work, right? You can't initiate traits, so you can't pass them to a method. Also instanceof with a trait will always be false I think.

Maybe you can try to use class_uses check?

[kylekatarnls]

Thanks. Indeed, I though class using a trait FooBar would return true with instanceof FooBar but it seems not. I'll re-open if I find the reason behind this code.

[ondrejmirtes]

I'd like the "impossible instanceof rule" to report it doesn't work with traits 😊

Also ObjectType::isSuperTypeOf() should return No if thisReflection or theirReflection is a trair.

[github-actions]

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