Incorrect inference of template definition using nested templates

[emmanuelGuiton]

Hi,

I would expected the 2 following snippets to work :
https://psalm.dev/r/f444f78efa
https://psalm.dev/r/f8c537da60

It seems Psalm does not get that it has the same template definition in Utils::aFunction() and in the Repository interface.
Am I missing anything ?

Regards,

• Emmanuel

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/f444f78efa

<?php

abstract class Id {}

/**
 * @template I of Id
 */
interface ObjectSpec {}

/**
 * @template I of Id
 * @template O of ObjectSpec<I>
 */
interface Repository{}

class Utils
{
	/**
	 * @template I of Id
	 * @template O of ObjectSpec<I>
	 * @psalm-param Repository<I, O> $repo
	 * @return void
	 */
	public static function aFunction(Repository $repo): void {}
}

Psalm output (using commit 10ea05a):

ERROR: InvalidTemplateParam - 21:18 - Extended template param O of Repository<I:fn-utils::afunction as Id, O:fn-utils::afunction as ObjectSpec<I:fn-utils::afunction as Id>> expects type ObjectSpec<I:Repository as Id>, type O:fn-utils::afunction as ObjectSpec<I:fn-utils::afunction as Id> given

https://psalm.dev/r/f8c537da60

<?php

abstract class Id {}

/**
 * @template I of Id
 */
interface ObjectSpec {}

/**
 * @template I of Id
 * @template O of ObjectSpec<I>
 */
interface Repository{}

/**
 * @template I of Id
 * @template O of ObjectSpec<I>
 */
class Utils
{
	/**
	 * @psalm-param Repository<I, O> $repo
	 * @return void
	 */
	public function aFunction(Repository $repo): void {}
}

Psalm output (using commit 10ea05a):

ERROR: InvalidTemplateParam - 23:18 - Extended template param O of Repository<I:Utils as Id, O:Utils as ObjectSpec<I:Utils as Id>> expects type ObjectSpec<I:Repository as Id>, type O:Utils as ObjectSpec<I:Utils as Id> given

[AndrolGenhald]

I think this is another case where Psalm's support for using nested templates is buggy 🙁

[emmanuelGuiton]

It seems I have yet another case : https://psalm.dev/r/dd644437de
Is there any work around ?

Note that though the Psalm issue points to the parameter O of AnEntity<I, O>, it disappears if extends DbEntityRepository is removed : https://psalm.dev/r/ad8477b7ea
It seems the Psalm is loosing control because of the parent class.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/dd644437de

<?php

// DATA MODEL
/** @template T */
interface AnId
{
	/**
	 * Getter for the internal value.
	 *
	 * @return T Internal value.
	 */
	public function getValue();
}

/** @template I of AnId */
abstract class AnObject
{
   	/**
	 * Getter for the identifier.
	 *
	 * @psalm-return I The identifier
	 */
	abstract public function getId();
}

// PERSISTENCE

/** @template T of object */
interface DbEntity
{
	/**
	 * Maps this entity to a data-model object
	 *
	 * @return object Data-model object to which this entity maps.
	 * @psalm-return T
	 */
	public function toModel(): object;
}

/**
 * Interface for all entities that map to data model object with an identifier.
 *
 * @template I of AnId
 * @template O of AnObject<I>
 * @extends DbEntity<O>
 */
interface AnEntity
extends DbEntity {}

/**
 * Repository of database entities.
 * @template T of object
 * @template E of DbEntity<T>
 */
abstract class DbEntityRepository {}

/**
 * Repository of database entities that maps to data model objects with identifiers.
 * @template I of AnId
 * @template O of AnObject<I>
 * @template E of AnEntity<I, O>
 * @extends DbEntityRepository<O, E>
 */
abstract class AnEntityRepository
extends DbEntityRepository
{}

Psalm output (using commit 8f39de9):

ERROR: InvalidTemplateParam - 64:16 - Extended template param O of AnEntity<I:AnEntityRepository as AnId, O:AnEntityRepository as AnObject<I:AnEntityRepository as AnId>> expects type AnObject<I:AnEntity as AnId>, type O:AnEntityRepository as AnObject<I:AnEntityRepository as AnId> given

https://psalm.dev/r/ad8477b7ea

<?php

// DATA MODEL
/** @template T */
interface AnId
{
	/**
	 * Getter for the internal value.
	 *
	 * @return T Internal value.
	 */
	public function getValue();
}

/** @template I of AnId */
abstract class AnObject
{
   	/**
	 * Getter for the identifier.
	 *
	 * @psalm-return I The identifier
	 */
	abstract public function getId();
}

// PERSISTENCE

/** @template T of object */
interface DbEntity
{
	/**
	 * Maps this entity to a data-model object
	 *
	 * @return object Data-model object to which this entity maps.
	 * @psalm-return T
	 */
	public function toModel(): object;
}

/**
 * Interface for all entities that map to data model object with an identifier.
 *
 * @template I of AnId
 * @template O of AnObject<I>
 * @extends DbEntity<O>
 */
interface AnEntity
extends DbEntity {}

/**
 * Repository of database entities.
 * @template T of object
 * @template E of DbEntity<T>
 */
abstract class DbEntityRepository {}

/**
 * Repository of database entities that maps to data model objects with identifiers.
 * @template I of AnId
 * @template O of AnObject<I>
 * @template E of AnEntity<I, O>
 */
abstract class AnEntityRepository
{}

Psalm output (using commit 8f39de9):

No issues!

[emmanuelGuiton]

I think the simplest case to reproduce the issue is that one : https://psalm.dev/r/6531496dba
Psalm behaves correctly when there are 2 nested templates, it fails with 3 nested templates.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/73c1e5aa67

<?php

/** @template T */
interface A {}

/**
 * @template T
 * @template U of A<T>
 */
interface B {}

/**
 * @template T
 * @template U of A<T>
 * @template V of B<T, U>
 */
interface C {}
     
/** @template T */
interface J {}
     
/**
 * @template T
 * @template U of A<T>
 * @template V of B<T, U>
 * @implements J<V>
 */
class K1 implements J {} // class with 3 nested template arguments : KO
     
/**
 * @template T
 * @template U of A<T>
 * @implements J<U>
 */
class K2 implements J {} // class with 2 nested template arguments : OK

/**
 * @template T
 * @template U of A<T>
 * @template V of B<T, U>
 * @extends J<V>
 */
interface K3 extends J {} // interface with 3 nested template arguments : OK

Psalm output (using commit 8f39de9):

ERROR: InvalidTemplateParam - 28:7 - Extended template param U of B<T:K1 as mixed, U:K1 as A<T:K1 as mixed>> expects type A<T:B as mixed>, type U:K1 as A<T:K1 as mixed> given

[emmanuelGuiton]

I was wrong, here is a definitely simpler example : https://psalm.dev/r/a89a8f3138

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/a89a8f3138

<?php

/** @template T */
interface A {}

/**
 * @template T
 * @template U of A<T>
 */
interface B {}
     
/** @template T */
interface J {}
     
/**
 * @implements J<B<object, A<object>>>
 */
class K1 implements J {} // class with 3 nested template arguments : KO

Psalm output (using commit 8f39de9):

ERROR: InvalidTemplateParam - 18:7 - Extended template param U of B<object, A<object>> expects type A<T:B as mixed>, type A<object> given