Incompatible types found for T #7549

come-nc · 2022-02-01T11:10:36Z

Hello,

I am trying to fix an error we have in the Nextcloud codebase.

I reproduced the situation on psalm.dev:
https://psalm.dev/r/ab70e17540

I want the line 80 to be an error, because LoginFailed is not a child class of ARemoteWipeEvent.
But I want the line 79 to not be an error, because RemoteWipeStarted is a child class of ARemoteWipeEvent.

Psalm says: Incompatible types found for T (RemoteWipeStarted is not in ARemoteWipeEvent)
But RemoteWipeStarted extends ARemoteWipeEvent.

I tried to fix this by using template-covariant instead of template on IEventListener, but if I do so:

I have to remove the @param T $event annotation from the method
line 80 is no longer an error!

Any help or suggestion appreciated!

The text was updated successfully, but these errors were encountered:

psalm-github-bot · 2022-02-01T11:10:39Z

I found these snippets:

https://psalm.dev/r/ab70e17540

<?php

class Event {
}

class LoginFailed extends Event {
	/** @var string */
	private $loginName;

	public function __construct(string $loginName) {
		$this->loginName = $loginName;
	}

	public function getLoginName(): string {
		return $this->loginName;
	}
}

class RemoteWipeStarted extends ARemoteWipeEvent {
}

abstract class ARemoteWipeEvent extends Event {
}

/**
 * @template-implements IEventListener<ARemoteWipeEvent>
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof ARemoteWipeEvent)) {
			return;
		}
	}
}

/**
 * @template-implements IEventListener<LoginFailed>
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @since 17.0.0
 *
 * @template T of Event
 */
interface IEventListener {
	/**
	 * @param T $event
	 *
	 * @since 17.0.0
	 */
	public function handle(Event $event): void;
}

/**
	 * @template T of Event
	 * @param string $eventName preferably the fully-qualified class name of the Event sub class to listen for
	 * @psalm-param string|class-string<T> $eventName preferably the fully-qualified class name of the Event sub class to listen for
	 * @param string $className fully qualified class name (or ::class notation) of a IEventListener that can be built by the DI container
	 * @psalm-param class-string<IEventListener<T>> $className fully qualified class name that can be built by the DI container
	 * @param int $priority The higher this value, the earlier an event
	 *                      listener will be triggered in the chain (defaults to 0)
	 *
	 * @since 17.0.0
	 */
function addServiceListener(string $eventName, string $className, int $priority = 0): void
{
    $a = [$eventName,$className,$priority];
    echo count($a);
}

addServiceListener(LoginFailed::class, LoginFailedListener::class);
addServiceListener(RemoteWipeStarted::class, RemoteWipeActivityListener::class);
addServiceListener(LoginFailed::class, RemoteWipeActivityListener::class);

Psalm output (using commit 2e01e9b):

ERROR: InvalidArgument - 79:1 - Incompatible types found for T (RemoteWipeStarted is not in ARemoteWipeEvent)

ERROR: InvalidArgument - 80:1 - Incompatible types found for T (LoginFailed is not in ARemoteWipeEvent)

orklah · 2022-02-01T12:01:40Z

Hi, Psalm prevents you from pushing childs to a template that is only expecting parents. This is indeed because of the issue caused by covariance: https://psalm.dev/docs/annotating_code/templated_annotations/#template-covariance

When you add the covariant, psalm find a new error, because you receive a T as a param of handle. This could cause new issues if you use T to alter the collection/template.

However, you can tell Psalm that you won't change the collection by adding immutable annotations like this: https://psalm.dev/r/47078f5aab

With those, Psalm doesn't complain anymore

psalm-github-bot · 2022-02-01T12:01:51Z

I found these snippets:

https://psalm.dev/r/47078f5aab

<?php

class Event {
}

class LoginFailed extends Event {
	/** @var string */
	private $loginName;

	public function __construct(string $loginName) {
		$this->loginName = $loginName;
	}

	public function getLoginName(): string {
		return $this->loginName;
	}
}

class RemoteWipeStarted extends ARemoteWipeEvent {
}

abstract class ARemoteWipeEvent extends Event {
}

/**
 * @template-implements IEventListener<ARemoteWipeEvent>
 * @psalm-immutable
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof ARemoteWipeEvent)) {
			return;
		}
	}
}

/**
 * @template-implements IEventListener<LoginFailed>
 * @psalm-immutable
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @since 17.0.0
 *
 * @template-covariant T of Event
 * @psalm-immutable
 */
interface IEventListener {
	/**
	 * @param T $event
	 *
	 * @since 17.0.0
	 */
	public function handle(Event $event): void;
}

/**
	 * @template T of Event
	 * @param string $eventName preferably the fully-qualified class name of the Event sub class to listen for
	 * @psalm-param string|class-string<T> $eventName preferably the fully-qualified class name of the Event sub class to listen for
	 * @param string $className fully qualified class name (or ::class notation) of a IEventListener that can be built by the DI container
	 * @psalm-param class-string<IEventListener<T>> $className fully qualified class name that can be built by the DI container
	 * @param int $priority The higher this value, the earlier an event
	 *                      listener will be triggered in the chain (defaults to 0)
	 *
	 * @since 17.0.0
	 */
function addServiceListener(string $eventName, string $className, int $priority = 0): void
{
    $a = [$eventName,$className,$priority];
    echo count($a);
}

addServiceListener(LoginFailed::class, LoginFailedListener::class);
addServiceListener(RemoteWipeStarted::class, RemoteWipeActivityListener::class);
addServiceListener(LoginFailed::class, RemoteWipeActivityListener::class);

Psalm output (using commit 2e01e9b):

No issues!

come-nc · 2022-02-01T13:33:25Z

Hi, Psalm prevents you from pushing childs to a template that is only expecting parents. This is indeed because of the issue caused by covariance: https://psalm.dev/docs/annotating_code/templated_annotations/#template-covariance

When you add the covariant, psalm find a new error, because you receive a T as a param of handle. This could cause new issues if you use T to alter the collection/template.

However, you can tell Psalm that you won't change the collection by adding immutable annotations like this: https://psalm.dev/r/47078f5aab

With those, Psalm doesn't complain anymore

But in this case psalm does not complain about the call on line 80 which is incorrect (LoginFailed is not a subclass of ARemoteWipeEvent).
Is there any way I can tell psalm that I want $className to be a class that implements IEventListener<T> with $eventName being T or a subclass of T?

psalm-github-bot · 2022-02-01T13:33:34Z

I found these snippets:

https://psalm.dev/r/47078f5aab

<?php

class Event {
}

class LoginFailed extends Event {
	/** @var string */
	private $loginName;

	public function __construct(string $loginName) {
		$this->loginName = $loginName;
	}

	public function getLoginName(): string {
		return $this->loginName;
	}
}

class RemoteWipeStarted extends ARemoteWipeEvent {
}

abstract class ARemoteWipeEvent extends Event {
}

/**
 * @template-implements IEventListener<ARemoteWipeEvent>
 * @psalm-immutable
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof ARemoteWipeEvent)) {
			return;
		}
	}
}

/**
 * @template-implements IEventListener<LoginFailed>
 * @psalm-immutable
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @since 17.0.0
 *
 * @template-covariant T of Event
 * @psalm-immutable
 */
interface IEventListener {
	/**
	 * @param T $event
	 *
	 * @since 17.0.0
	 */
	public function handle(Event $event): void;
}

/**
	 * @template T of Event
	 * @param string $eventName preferably the fully-qualified class name of the Event sub class to listen for
	 * @psalm-param string|class-string<T> $eventName preferably the fully-qualified class name of the Event sub class to listen for
	 * @param string $className fully qualified class name (or ::class notation) of a IEventListener that can be built by the DI container
	 * @psalm-param class-string<IEventListener<T>> $className fully qualified class name that can be built by the DI container
	 * @param int $priority The higher this value, the earlier an event
	 *                      listener will be triggered in the chain (defaults to 0)
	 *
	 * @since 17.0.0
	 */
function addServiceListener(string $eventName, string $className, int $priority = 0): void
{
    $a = [$eventName,$className,$priority];
    echo count($a);
}

addServiceListener(LoginFailed::class, LoginFailedListener::class);
addServiceListener(RemoteWipeStarted::class, RemoteWipeActivityListener::class);
addServiceListener(LoginFailed::class, RemoteWipeActivityListener::class);

Psalm output (using commit 2e01e9b):

No issues!

AndrolGenhald · 2022-02-01T15:54:03Z

I thought this might work, but not quite. Second try was also a failure, but might work if #7553 is fixed.

This works if you're willing to add the extra function call. Or you could force it, but that's dangerous.

@orklah I think this should probably be reopened as an enhancement or bugfix to fix handling of templates as template constraints. I would expect something like this to work. For addServiceListener(RemoteWipeStarted::class, RemoteWipeActivityListener::class):

TEvent should resolve to ARemoteWipeEvent
TListener should resolve to RemoteWipeActivityListener
TCanBeChildEvent should resolve to RemoteWipeStarted.

psalm-github-bot · 2022-02-01T15:54:06Z

I found these snippets:

https://psalm.dev/r/e9779b57e9

<?php

class Event {
}

class LoginFailed extends Event {}

class RemoteWipeStarted extends ARemoteWipeEvent {}

abstract class ARemoteWipeEvent extends Event {}

/**
 * @template T of ARemoteWipeEvent
 * @implements IEventListener<T>
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
        assert($event instanceof ARemoteWipeEvent); // Should be redundant
	}
}

/**
 * @implements IEventListener<LoginFailed>
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @template T of Event
 */
interface IEventListener {
	public function handle(Event $event): void;
}

/**
 * @template TEvent of Event
 * @template TListener of IEventListener<TEvent>
 * @param class-string<TEvent> $eventName
 * @param class-string<TListener> $className
 */
function addServiceListener(string $eventName, string $className, int $priority = 0): void
{
    $a = [$eventName,$className,$priority];
    echo count($a);
}

addServiceListener(LoginFailed::class, LoginFailedListener::class);
addServiceListener(ARemoteWipeEvent::class, RemoteWipeActivityListener::class); // Incorrect
addServiceListener(RemoteWipeStarted::class, RemoteWipeActivityListener::class); // Incorrect
addServiceListener(LoginFailed::class, RemoteWipeActivityListener::class); // Correctly invalid

Psalm output (using commit 2e01e9b):

ERROR: InvalidArgument - 53:1 - Incompatible types found for TEvent (ARemoteWipeEvent is not in T:RemoteWipeActivityListener as ARemoteWipeEvent)

ERROR: InvalidArgument - 54:1 - Incompatible types found for TEvent (RemoteWipeStarted is not in T:RemoteWipeActivityListener as ARemoteWipeEvent)

ERROR: InvalidArgument - 55:1 - Incompatible types found for TEvent (LoginFailed is not in T:RemoteWipeActivityListener as ARemoteWipeEvent)

https://psalm.dev/r/c88688bf94

<?php

class Event {
}

class LoginFailed extends Event {}

class RemoteWipeStarted extends ARemoteWipeEvent {}

abstract class ARemoteWipeEvent extends Event {}

/**
 * @template T of ARemoteWipeEvent
 * @implements IEventListener<T>
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
        assert($event instanceof ARemoteWipeEvent); // Correctly redundant
	}
}

/**
 * @implements IEventListener<LoginFailed>
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @template T of Event
 */
interface IEventListener {
	/**
	 * @param T $event
	 */
	public function handle(Event $event): void;
}

/**
 * @template TEvent of Event
 * @template TListener of IEventListener<TEvent>
 */
class ServiceListenerManager
{
    /** @param class-string<TListener> $listenerClass */
    public function __construct(
        private string $listenerClass,
    ) {}
    
    /**
     * @template TChildEvent of TEvent
 	 * @param class-string<TChildEvent> $eventName
	 */
	public function addServiceListener(string $eventName, string $className, int $priority = 0): void
	{
    	$a = [$eventName,$className,$priority];
    	echo count($a);
	}
}

$lfslm = new ServiceListenerManager(LoginFailedListener::class);
$lfslm->addServiceListener(LoginFailed::class, LoginFailedListener::class);
$rwslm = new ServiceListenerManager(RemoteWipeActivityListener::class);
$rwslm->addServiceListener(ARemoteWipeEvent::class, RemoteWipeActivityListener::class);
$rwslm->addServiceListener(RemoteWipeStarted::class, RemoteWipeActivityListener::class);
/** @psalm-trace $rwslm */;
// $rwslm is ServiceListenerManager<T:RemoteWipeActivityListener as ARemoteWipeEvent, RemoteWipeActivityListener>
// Why is TChildEvent allowed to be LoginFailed?
$rwslm->addServiceListener(LoginFailed::class, RemoteWipeActivityListener::class); // Should be invalid

Psalm output (using commit 2e01e9b):

INFO: Trace - 70:27 - $rwslm: ServiceListenerManager<T:RemoteWipeActivityListener as ARemoteWipeEvent, RemoteWipeActivityListener>

ERROR: RedundantConditionGivenDocblockType - 18:9 - Docblock-defined type T:RemoteWipeActivityListener as ARemoteWipeEvent for $event is always ARemoteWipeEvent

https://psalm.dev/r/b982ff8efd

<?php

class Event {
}

class LoginFailed extends Event {}

class RemoteWipeStarted extends ARemoteWipeEvent {}

abstract class ARemoteWipeEvent extends Event {}

/**
 * @implements IEventListener<ARemoteWipeEvent>
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
        assert($event instanceof ARemoteWipeEvent); // Should be redundant
	}
}

/**
 * @implements IEventListener<LoginFailed>
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @template T of Event
 */
interface IEventListener {
    /** @param T $event */
	public function handle(Event $event): void;
}

/**
 * @template TEvent of Event
 * @template TListener of IEventListener<TEvent>
 * @param class-string<TEvent> $eventName
 * @param class-string<TListener> $className
 */
function addServiceListener(string $eventName, string $className, int $priority = 0): void
{
    $a = [$eventName,$className,$priority];
    echo count($a);
}

addServiceListener(LoginFailed::class, LoginFailedListener::class);
addServiceListener(widenRemoteWipeEvent(ARemoteWipeEvent::class), RemoteWipeActivityListener::class); // Incorrect
addServiceListener(widenRemoteWipeEvent(RemoteWipeStarted::class), RemoteWipeActivityListener::class); // Incorrect
addServiceListener(widenRemoteWipeEvent(LoginFailed::class), RemoteWipeActivityListener::class); // Correctly invalid

/**
 * @param class-string<ARemoteWipeEvent> $arg
 * @return class-string<ARemoteWipeEvent>
 */
function widenRemoteWipeEvent(string $arg): string
{
    return $arg;
}

Psalm output (using commit 2e01e9b):

ERROR: InvalidArgument - 55:41 - Argument 1 of widenRemoteWipeEvent expects class-string<ARemoteWipeEvent>, LoginFailed::class provided

ERROR: RedundantConditionGivenDocblockType - 17:9 - Docblock-defined type ARemoteWipeEvent for $event is always ARemoteWipeEvent

https://psalm.dev/r/ce8cf4e36d

<?php

class Event {
}

class LoginFailed extends Event {}

class RemoteWipeStarted extends ARemoteWipeEvent {}

abstract class ARemoteWipeEvent extends Event {}

/**
 * @implements IEventListener<ARemoteWipeEvent>
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
        assert($event instanceof ARemoteWipeEvent); // Correctly redundant
	}
}

/**
 * @implements IEventListener<LoginFailed>
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @template T of Event
 */
interface IEventListener {
    /**
     * @template TChildEvent of T
     * @param T $event
     */
	public function handle(Event $event): void;
}

/**
 * @template TEvent of Event
 * @template TListener of IEventListener<TEvent>
 * @param class-string<TEvent> $eventName
 * @param class-string<TListener> $className
 */
function addServiceListener(string $eventName, string $className, int $priority = 0): void
{
    $a = [$eventName,$className,$priority];
    echo count($a);
}

/** @var class-string<ARemoteWipeEvent> */
$eventName = RemoteWipeStarted::class;
addServiceListener($eventName, RemoteWipeActivityListener::class);

Psalm output (using commit 2e01e9b):

ERROR: RedundantConditionGivenDocblockType - 17:9 - Docblock-defined type ARemoteWipeEvent for $event is always ARemoteWipeEvent

https://psalm.dev/r/25a36f3820

<?php

class Event {
}

class LoginFailed extends Event {}

class RemoteWipeStarted extends ARemoteWipeEvent {}

abstract class ARemoteWipeEvent extends Event {}

/**
 * @implements IEventListener<ARemoteWipeEvent>
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
        assert($event instanceof ARemoteWipeEvent); // Correctly redundant
	}
}

/**
 * @implements IEventListener<LoginFailed>
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @template T of Event
 */
interface IEventListener {
    /**
     * @template TChildEvent of T
     * @param T $event
     */
	public function handle(Event $event): void;
}

/**
 * @template TEvent of Event
 * @template TListener of IEventListener<TEvent>
 * @param class-string<TEvent> $eventName
 * @param class-string<TListener> $className
 */
function addServiceListener(string $eventName, string $className, int $priority = 0): void
{
    $a = [$eventName,$className,$priority];
    echo count($a);
}

/** @var class-string<ARemoteWipeEvent> */
$eventName = LoginFailed::class;
addServiceListener($eventName, RemoteWipeActivityListener::class);

Psalm output (using commit 2e01e9b):

ERROR: RedundantConditionGivenDocblockType - 17:9 - Docblock-defined type ARemoteWipeEvent for $event is always ARemoteWipeEvent

https://psalm.dev/r/6f8179ebe7

<?php

class Event {
}

class LoginFailed extends Event {}

class RemoteWipeStarted extends ARemoteWipeEvent {}

abstract class ARemoteWipeEvent extends Event {}

/**
 * @implements IEventListener<ARemoteWipeEvent>
 */
class RemoteWipeActivityListener implements IEventListener {
	public function handle(Event $event): void {
        assert($event instanceof ARemoteWipeEvent); // Should be redundant
	}
}

/**
 * @implements IEventListener<LoginFailed>
 */
class LoginFailedListener implements IEventListener {
	public function handle(Event $event): void {
		if (!($event instanceof LoginFailed)) {
			return;
		}
	}
}

/**
 * @template T of Event
 */
interface IEventListener {
    /**
     * @template TCanBeChildEvent of T
     * @param TCanBeChildEvent $event
     */
	public function handle(Event $event): void;
}

/**
 * @template TEvent of Event
 * @template TCanBeChildEvent of TEvent
 * @template TListener of IEventListener<TEvent>
 * @param class-string<TCanBeChildEvent> $eventName
 * @param class-string<TListener> $className
 */
function addServiceListener(string $eventName, string $className, int $priority = 0): void
{
    $a = [$eventName,$className,$priority];
    echo count($a);
}

addServiceListener(LoginFailed::class, LoginFailedListener::class);
addServiceListener(ARemoteWipeEvent::class, RemoteWipeActivityListener::class);
addServiceListener(RemoteWipeStarted::class, RemoteWipeActivityListener::class);
addServiceListener(LoginFailed::class, RemoteWipeActivityListener::class); // Invalid

Psalm output (using commit 2e01e9b):

ERROR: InvalidArgument - 58:1 - Incompatible types found for TEvent (RemoteWipeStarted is not in ARemoteWipeEvent)

ERROR: InvalidArgument - 59:1 - Incompatible types found for TEvent (LoginFailed is not in ARemoteWipeEvent)

come-nc · 2023-09-12T14:45:37Z

I think this can be closed, the snippet I posted in the first post now behaves as expected on psalm.dev (you can compare with the result from when I opened this)

orklah closed this as completed Feb 1, 2022

orklah reopened this Feb 1, 2022

orklah added bug templates labels Feb 1, 2022

come-nc mentioned this issue Feb 14, 2022

Incompatible types found for T ChristophWurst/nextcloud_composer#13

Open

AndrolGenhald mentioned this issue Mar 9, 2022

Closure return type not considered with @template annotation. #7764

Open

AndrolGenhald mentioned this issue Mar 16, 2022

Template params not allowing extending other template params #7795

Open

juliusknorr mentioned this issue Jul 28, 2022

Improve container return type annotations nextcloud/server#33388

Merged

come-nc mentioned this issue Apr 3, 2023

Drop IEventListener template parameter nextcloud/server#37506

Closed

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Incompatible types found for T #7549

Incompatible types found for T #7549

come-nc commented Feb 1, 2022

psalm-github-bot bot commented Feb 1, 2022

orklah commented Feb 1, 2022

psalm-github-bot bot commented Feb 1, 2022

come-nc commented Feb 1, 2022 •

edited

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psalm-github-bot bot commented Feb 1, 2022

AndrolGenhald commented Feb 1, 2022

psalm-github-bot bot commented Feb 1, 2022

come-nc commented Sep 12, 2023

Incompatible types found for T #7549

Incompatible types found for T #7549

Comments

come-nc commented Feb 1, 2022

psalm-github-bot bot commented Feb 1, 2022

orklah commented Feb 1, 2022

psalm-github-bot bot commented Feb 1, 2022

come-nc commented Feb 1, 2022 • edited Loading

psalm-github-bot bot commented Feb 1, 2022

AndrolGenhald commented Feb 1, 2022

psalm-github-bot bot commented Feb 1, 2022

come-nc commented Sep 12, 2023

come-nc commented Feb 1, 2022 •

edited

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