Psalm doesn't accept generic invokable class as callable

[klimick]

Bug or type inference limitation?

https://psalm.dev/r/6df07c8d07

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/6df07c8d07

<?php

class OrderId
{
    public string $value;

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

/**
 * @template A
 * @template B
 */
class _Callable
{
    /** @var callable(A): B */
    private $fn;

    /**
     * @param callable(A): B $fn
     */
    public function __construct(callable $fn)
    {
        $this->fn = $fn;
    }

    /**
     * @param A $a
     * @return B
     */
	public function __invoke($a)
    {
        return ($this->fn)($a);
    }

    /**
     * @return callable(A): B
     */
    public function unwrap(): callable
    {
    	return $this->fn;
    }
}

/**
 * @param callable(string): OrderId $_
 */
function testCallable(callable $_): void
{
}

testCallable(
	fn(string $value) => new OrderId($value)
);

testCallable((
    new _Callable(fn(string $value) => new OrderId($value))
)->unwrap());

testCallable(
	new _Callable(fn(string $value) => new OrderId($value))
);

Psalm output (using commit f65868c):

ERROR: InvalidArgument - 64:2 - Argument 1 of testCallable expects callable(string):OrderId, _Callable<string, OrderId> provided

[thomasvargiu]

Even with functions: https://psalm.dev/r/a51288e0e0

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/a51288e0e0

<?php

/**
 * @template B
 */
class A {
    /** @var B */
    private $value;
    /** @param B $value */
    public function __construct($value) {
        $this->value = $value;
    }
    /** @return B */
    public function __invoke()
    {
        return $this->value;
    }
}

$a = new A('foo');
/** @psalm-trace $v */
$v = Closure::fromCallable($a);

/** @psalm-trace $r */
$r = $v();

Psalm output (using commit fd53192):

INFO: Trace - 22:1 - $v: impure-Closure():B:A as mixed

INFO: Trace - 25:1 - $r: B:A as mixed

[klimick]

Fixed in #7417