LessSpecificReturnStatement + MoreSpecificReturnType reported together

[bendavies]

See: https://psalm.dev/r/4c0bab583c

If we change line 28 to
@return (T&Baz)|null
(switching Baz and T), then there are no errors.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/4c0bab583c

<?php

class Foo
{

    /**
     * @psalm-var class-string
     * @var string 
     */
    private $class = Bar::class;

  	/**
     * @return class-string
     */
    public function getClass(): string
    {
        return $this->class;
    }
}

interface Baz {}

class Bar implements Baz
{
    /**
     * @template T
     * @psalm-param class-string<T> $class
     * @return (Baz&T)|null
     */
    public function instantiator(string $class): ?Baz
    {
		return rand(0, 1) ? new $class() : null;
    }
}

$foo = new Foo();
$bar = new Bar();
$bar->instantiator($foo->getClass());

Psalm output (using commit 234a6ba):

INFO: LessSpecificReturnStatement - 32:10 - The type 'T:fn-bar::instantiator as object|null' is more general than the declared return type 'Baz&(T:fn-bar::instantiator as object)|null' for Bar::instantiator

INFO: MoreSpecificReturnType - 28:16 - The declared return type 'Baz&(T:fn-bar::instantiator as object)|null' for Bar::instantiator is more specific than the inferred return type 'T:fn-bar::instantiator as object|null'

[weirdan]

Order-dependence is unexpected, but wouldn't it make more sense to declare the types like this: https://psalm.dev/r/462ae2c353

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/462ae2c353

<?php

class Foo
{

    /**
     * @psalm-var class-string
     * @var string 
     */
    private $class = Bar::class;

  	/**
     * @return class-string
     */
    public function getClass(): string
    {
        return $this->class;
    }
}

interface Baz {}

class Bar implements Baz
{
    /**
     * @template T of Baz
     * @psalm-param class-string<T> $class
     * @return ?T
     */
    public function instantiator(string $class): ?Baz
    {
		return rand(0, 1) ? new $class() : null;
    }
}

$foo = new Foo();
$bar = new Bar();
$bar->instantiator($foo->getClass());

Psalm output (using commit 712806b):

ERROR: ArgumentTypeCoercion - 38:20 - Argument 1 of Bar::instantiator expects class-string<Baz>, parent type class-string provided

[bendavies]

i wasn't aware of that syntax. thanks

[muglug]

Yes, order-dependence is still a bug

[bendavies]

seems phpstan doesn't like @template T of Foo unfortunately. (i run both)

[weirdan]

Works for me: https://phpstan.org/r/c5b43fd7-f415-43fa-aacf-159a2a3123c8

[muglug]

distilled down, these should both be errors: https://psalm.dev/r/7c42967494

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/7c42967494

<?php

interface Bar {}
interface Baz {}

/**
 * @template T
 * @psalm-param class-string<T> $class
 * @return T&Baz
 */
function returnsTemplatedIntersection(string $class) {
  return new $class();
}

/**
 * @return Bar&Baz
 */
function returnsIntersection(Bar $bar) {
  return $bar;
}

Psalm output (using commit f9f49f1):

ERROR: InvalidReturnStatement - 19:10 - The type 'Bar' does not match the declared return type 'Bar&Baz' for returnsIntersection

ERROR: InvalidReturnType - 16:12 - The declared return type 'Bar&Baz' for returnsIntersection is incorrect, got 'Bar'

[bendavies]

Works for me: phpstan.org/r/c5b43fd7-f415-43fa-aacf-159a2a3123c8

huh, thanks. i got an error. i'll look into it another time.