Add Property::isVirtual()

[JanTvrdik]

In order to determine whether property is writable, it is now required among other thing to determine if property is virtual, which requires iterating over body of property hooks.

It would be helpful if new isVirtual() method was added to Property class.

As far as I can tell, this is the C implementation that the PHP code should match.

[nikic]

This sounds like useful information to provide. As it requires a full recursive traversal of the body, this probably has to be via a visitor that adds an attribute?

[JanTvrdik]

Visitor adding attribute would be one option.

Another would to locally recusively iterate over hooks nodes.

/**
 * Whether the property is virtual.
 */
public function isVirtual(): bool {
    if (\count($this->hooks) === 0) {
        return false;
    }

    foreach ($this->hooks as $hook) {
        if ($hook->body instanceof Node\Expr) {
            if ($hook->name->name === 'set' || $this->isHookUsingProperty([$hook->body])) {
                return false;
            }
        } elseif (\is_array($hook->body)) {
            if ($this->isHookUsingProperty($hook->body)) {
                return false;
            }
        }
    }

    return true;
}

/**
 * @param array<mixed> $nodes
 */
private function isHookUsingProperty(array $nodes): bool {
    foreach ($nodes as $node) {
        if ($node instanceof Node\Expr\PropertyFetch || $node instanceof Node\Expr\NullsafePropertyFetch) {
            if ($node->name->name === $this->props[0]->name->name && $node->var instanceof Node\Expr\Variable && $node->var->name === 'this') {
                return true;
            }
        }

        if ($node instanceof Node) {
            foreach ($node->getSubNodeNames() as $name) {
                if ($this->isHookUsingProperty(\is_array($node->$name) ? $node->$name : [$node->$name])) {
                    return true;
                }
            }
        }
    }

    return false;
}

[ondrejmirtes]

I guess this code is a bit wrong when anonymous classes are involved in the hook body: https://3v4l.org/uumta

[ondrejmirtes]

And maybe we can confuse the PHP algorithm with closures that have $this bound to a different object.

[ondrejmirtes]

Even a hook like this still makes property virtual: https://3v4l.org/tLqed