InvalidTemplateParam in a complex example with nested templates

[vudaltsov]

Here's a snippet with all necessary for understanding comments.

https://psalm.dev/r/51e2a255ea

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/51e2a255ea

<?php

/**
 * Value object that describes a transformation.
 *
 * @psalm-immutable
 * @template TFrom
 * @template TTo
 */
interface Transformation
{
}

/**
 * Service that handles some transformation.
 *
 * @template TFrom
 * @template TTo
 * @template TTransformation of Transformation<TFrom, TTo>
 */
interface Transformer
{
    /**
     * @return class-string<TTransformation>
     */
    public static function transformation(): string;

    /**
     * @param TFrom $value
     * @param TTransformation $transformation
     * @return TTo
     */
    public function transform(mixed $value, Transformation $transformation): mixed;
}

/**
 * Locator of transfomers.
 */
interface TransformerRegistry
{
    /**
     * @template TFrom
     * @template TTo
     * @template TTransformation of Transformation<TFrom, TTo>
     * @param class-string<TTransformation> $transformation
     * @return ?Transformer<TFrom, TTo, TTransformation>
     */
    public function get(string $transformation): ?Transformer;
}

/**
 * A pipeline that holds the value, to which transformations can be applied.
 *
 * @template T
 */
final class Pipeline
{
    /**
     * @param T $value
     */
    public function __construct(
        private mixed $value,
        private TransformerRegistry $transformerRegistry,
    ) {
    }

    /**
     * @template TNew
     * @param Transformation<T, TNew> $transformation
     * @return self<TNew>
     */
    public function transform(Transformation $transformation): self
    {
        $transformer = $this
                ->transformerRegistry
                ->get($transformation::class)
            ?? throw new InvalidArgumentException('No transformer for transformation.')
        ;

        return new self(
            $transformer->transform($this->value, $transformation),
            $this->transformerRegistry,
        );
    }
}

/**
 * @psalm-immutable
 * @template T of object
 * @implements Transformation<mixed, T>
 */
final class Hydrate implements Transformation
{
    /**
     * @param class-string<T> $class
     */
    public function __construct(
        public string $class,
    ) {
    }
}

/**
 * @template T of object
 * @implements Transformer<mixed, object, Hydrate<T>>
 */
final class Hydrator implements Transformer
{
    // Symfony Denormalizer is injeceted here, for example.
    
    public static function transformation(): string
    {
        /** @var class-string<Hydrate<T>> */
        return Hydrate::class;
    }

    public function transform(mixed $value, Transformation $transformation): mixed
    {
        /** 
         * Should be $this->denormalizer->denormalize(...), for now a simple placeholder.
         *
         * @psalm-suppress MixedMethodCall
         */
        return new $transformation->class();
    }
}

Psalm output (using commit 6f1d438):

ERROR: InvalidTemplateParam - 46:16 - Extended template param TTransformation of Transformer<TFrom:fn-transformerregistry::get as mixed, TTo:fn-transformerregistry::get as mixed, TTransformation:fn-transformerregistry::get as Transformation<TFrom:fn-transformerregistry::get as mixed, TTo:fn-transformerregistry::get as mixed>> expects type Transformation<TFrom:Transformer as mixed, TTo:Transformer as mixed>, type TTransformation:fn-transformerregistry::get as Transformation<TFrom:fn-transformerregistry::get as mixed, TTo:fn-transformerregistry::get as mixed> given

[VincentLanglet]

I think https://psalm.dev/r/1fe7ccd2fd could be a simpler example @orklah

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/1fe7ccd2fd

<?php

/** @phpstan-template T of object */
interface Bar {}

/**
 * @phpstan-template T of object
 * @phpstan-template B of Bar<T>
 */
class Foo
{
}

class Test
{
    /** @phpstan-var Foo<object, Bar<object>> */
    private $foo;
    
    public function __construct() 
    {
        $this->foo = new Foo();
    }
}

Psalm output (using commit b5b5c20):

ERROR: InvalidTemplateParam - 16:22 - Extended template param B of Foo<object, Bar<object>> expects type Bar<T:Foo as object>, type Bar<object> given

ERROR: InvalidPropertyAssignmentValue - 21:22 - $this->foo with declared type 'Foo<object, Bar<object>>' cannot be assigned type 'Foo<object, Bar<T:Foo as object>>'