InvalidCast when working with ::class on generics

[davidbyoung]

I copy/pasted the relevant parts of my code here: https://psalm.dev/r/13175e171b. When dealing with somewhat complex constrained generics, using ::class gives me an InvalidCast {NameOfClass} cannot be cast to string. This is happening on the master branch of Psalm.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/13175e171b

<?php

class AuthenticationSchemeOptions {}

/**
 * @template T of AuthenticationSchemeOptions
 */
class AuthenticationScheme
{
    /**
     * @param class-string<IAuthenticationSchemeHandler<T>> $handlerClassName The name of the authentication scheme handler class used by this scheme
     * @param T $options The options for this scheme
     */
    public function __construct(
        public readonly string $handlerClassName,
        public readonly AuthenticationSchemeOptions $options = new AuthenticationSchemeOptions()
    ) {
    }
}

/**
 * @template T of AuthenticationSchemeOptions
 */
interface IAuthenticationSchemeHandler {}

interface IAuthenticationSchemeHandlerResolver
{
    /**
     * @template TSchemeOptions of AuthenticationSchemeOptions
     * @template THandler of IAuthenticationSchemeHandler<TSchemeOptions>
     * @param class-string<THandler> $authenticationHandlerClassName
     * @return THandler The resolved authentication handler
     */
    public function resolve(string $authenticationHandlerClassName): IAuthenticationSchemeHandler;
}

class CookieAuthenticationOptions extends AuthenticationSchemeOptions {}

/**
 * @implements IAuthenticationSchemeHandler<CookieAuthenticationOptions>
 */
class CookieAuthenticationHandler implements IAuthenticationSchemeHandler {}


/** @var IAuthenticationSchemeHandlerResolver $resolver */
$resolver->resolve(CookieAuthenticationHandler::class);

Psalm output (using commit c3cc906):

ERROR: InvalidCast - 46:20 - CookieAuthenticationHandler cannot be cast to string

[weirdan]

Simplified a bit: https://psalm.dev/r/db793e0df3

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/db793e0df3

<?php

/** @template-covariant T of Throwable */
interface Box {}

/** @implements Box<Exception> */
class ExceptionBox implements Box {}

interface Packer
{
    /**
     * @template TBox of Box
     * @param class-string<TBox> $boxClass
     * @return TBox
     */
    public function pack(string $boxClass): Box;
}

/** @var Packer $packer */
$packer->pack(ExceptionBox::class);

Psalm output (using commit c3cc906):

ERROR: InvalidCast - 20:15 - ExceptionBox cannot be cast to string

[orklah]

That's really weird, Psalm transforms the TLiteralClassString into a TNamedObject at some point and then complains it can't cast it to string...

[vudaltsov]

Looking forward to the fix. We have many such issues in our project.

[roxblnfk]

Yet another example https://psalm.dev/r/80771a0b51

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/80771a0b51

<?php

declare(strict_types=1);

/**
 * @template TClass of object
 */
interface InjectorInterface
{
    /**
     * @return TClass
     */
    public function createInjection(): object;
}
class Binder
{
    /**
     * @template TClass of object
     *
     * @param class-string<TClass> $class
     * @param class-string<InjectorInterface<TClass>> $injector
     */
    public function bindInjector(string $class, string $injector): void
    {}
}

interface CacheInterface {}
/**
 * @implements InjectorInterface<CacheInterface>
 */
class CacheInjector implements InjectorInterface {
    public function createInjection(): CacheInterface
    {
        return new class implements CacheInterface {};
    }
}


(new Binder)->bindInjector(CacheInterface::class, CacheInjector::class);

Psalm output (using commit 82b3a7c):

ERROR: InvalidCast - 39:51 - CacheInjector cannot be cast to string

[orklah]

Fixed by @klimick on #9738 \o/

[vudaltsov]

Awesome, thank you!