Can I check if ReflectionType is instance of another type?

I want to check if a callable's return type is an instance of another type. For example, let's say I a have:

1. A class Pigeon which extends Animal.
2. A function addSupplier() which takes a callable argument and expects the return type to be Animal.
3. A call to addSupplier() which passes a closure that returns a Pigeon.

Here is the example in code:

namespace Foo\Bar;

class Animal {
    // ...
}

class Pigeon extends Animal {
    // ...
}

class Suppliers {

    public static function test() {
        self::addSupplier(fn() => new Pigeon());
    }

    public static function addSupplier(callable $callable) {
        $reflection = new ReflectionFunction($callable);
        $type = $reflection->getReturnType();

        if($type->isInstance('\Foo\Bar\Animal')) { // Pseudocode
            // It's an animal!
        } else
            throw new InvalidArgumentException("Callable must return an animal!");
    }
    
}

Is there a way that addSupplier can check the the return type of the callable parameter to ensure that it will be an instance of Animal?

As currently written your callable will eventually return a Pigeon instance, but is not constrainted to do that. If you add a return type hint, your requirement can be implemented. Have a look at this modification:

<?php

namespace Foo\Bar;

class Animal {
    // ...
}

class Pigeon extends Animal {
    // ...
}

class Suppliers {

    public static function test() {
        self::addSupplier(fn(): Pigeon => new Pigeon());
    }

    public static function addSupplier(callable $callable) {
        $reflection = new \ReflectionFunction($callable);
        $type = $reflection->getReturnType();
        if($type && (new \ReflectionClass($type->getName()))->isSubclassOf('\Foo\Bar\Animal')) {
            print("It's an animal!");
        } else
            throw new \InvalidArgumentException("Callable must return an animal!");
    }
    
}

Suppliers::test();

Remove the : Pigeon hint to see the other case.