How to deal with command / event busses?

[ruudk]

Let's say you have the following:

class MyHandler {
    public function __construct(private SomeDependency $dep) {}

    public function __invoke(MyCommand $command) {}
}

class MyCommand {
    public function __construct(public string $name) {}
}

class MyController {
    public function __invoke() {
        $this->commandBus->dispatch(new MyCommand('Ruud'));
    }
}

The above should return in no dead classes.

But when MyCommand is not dispatched anywhere, it should mark MyHandler + MyCommand as dead.

Same with an Event and multiple event subscribers to that event. If the event is never dispatched, the event + all the subscribers should be marked as dead.

https://symfony.com/doc/current/components/messenger.html

[janedbal]

I believe that in order to support this (and #83), we need some HiddenCallProvider which will be based on AST, not based on reflection like EntrypointProvider is.

[janedbal]

Since 0.7.0, we can deduce usages from AST, but I'm still unsure if it can solve this problem.

Because when we are analysing $this->commandBus->dispatch, we would need to know which handler have the MyCommand in its __invoke method to be able to mark it as used. This is possible in PHPStan only via collectors, which might be really tricky to inject into dead-code-detector's extension point without breaking its performance (mainly because you MUST NOT use reflection in all CollectedData rules).

Or do you see any option without collector-like logic?