InvalidPropertyFetch error emmited on accessing static properties

[emodric]

After upgrading from 3.11.5 to 3.11.6 I started getting InvalidPropertyFetch error on accessing static properties where class name is stored in a variable.

Issue reproducer at https://psalm.dev/r/7bad6b85e8

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/7bad6b85e8

<?php

declare(strict_types=1);

namespace Foo;

class Bar
{
    public static string $foo = 'bar';
}

$class = Bar::class;

echo isset($class::$foo) ? (string) $class::$foo : '';

Psalm output (using commit 137647a):

ERROR: InvalidPropertyFetch - 14:12 - Cannot fetch property on non-object $class of type class-string

[mr-feek]

@muglug happy to make a PR if you'd like to provide some guidance :)

[muglug]

@mr-feek I think the solution is to narrow this check to only match when $stmt->class has an object (where some $stmt_class_type->hasObjectType()

[muglug]

so you'll need to run that expression through ExpressionAnalyzer::analyze so the $statements_analyzer->node_data has the correct type

[muglug]

Actually let me have a go at this, it's a little tricky

[mr-feek]

hah, i gave it a go here https://github.com/vimeo/psalm/compare/master...mr-feek:fix-class-name-static-props-access?expand=1 @muglug

[muglug]

Thanks, I realised my suggestion would still break in this scenario:

class Beep {
    public static string $boop = "boop";
}
$beep = rand(0, 1) ? new Beep() : Beep::class;
echo $beep::$boop;

so ended up with something a little more complex

[mr-feek]

Thanks @muglug ! Do you consider "hotfix releases" in order to fix regressions so we don't have to wait ~ 2 weeks for the next release?

[emodric]

A hotfix release would be great, to fix our CI!

Thanks @mr-feek and @muglug for speedy fix 👍

[muglug]

Yeah I should have a release this weekend

[TysonAndre]

I still see this when the class name is returned by get_class() - https://psalm.dev/r/6fa0f75968

Maybe a different issue type should be emitted for unanalyzable static property fetches when the class is a string?

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/6fa0f75968

<?php
class MyClass {
    /** @var string */
    public static $prop = 'value';
}
function test(MyClass $c): void {
    $x = get_class($c);
    var_export($x::$prop);
}
test(new MyClass());

Psalm output (using commit 29eb830):

ERROR: InvalidPropertyFetch - 8:16 - Cannot fetch property on non-object $__fake_var_155 of type string

[emodric]

This one too still has issues:

https://psalm.dev/r/2835c940a7

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/2835c940a7

<?php

class Foo
{
    public static string $bar = 'baz';
}

function getClass(): string
{
    return 'Foo';
}

$class = getClass();

echo (string) $class::$foo;

Psalm output (using commit 9b86021):

ERROR: InvalidPropertyFetch - 15:15 - Cannot fetch property on non-object $__fake_var_148 of type string

[sapphirecat]

Found this issue because I am seeing this happen on 3.13.1. (In my actual code base, Psalm knows it's of type class-string, but the error on the site is displaying as "of type string". I'm not sure why that happens, or if that's important.)

https://psalm.dev/r/ecc58fd19f

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/ecc58fd19f

<?php

class Controller {
    /** @var Array<string,string> $scope */
    public static array $scope = ['getCustomer' => 'read', 'putCustomer' => 'write'];
    public function getCustomer(): void {}
    public function putCustomer(): void {}
}

class Middleware {
    /**
     * @var class-string $controller
     * @var list<string> $grants
     */
    public function validateAccess(string $controller, string $method, array $grants): void {
        if (! isset($controller::$scope)) {
            throw new Exception("Access Denied");
        }
        // ... then check $controller::$scope[$method] vs $grants ...
    }
}

$m = new Middleware();
$m->validateAccess(Controller::class, 'getCustomer', ['read', 'write']);

Psalm output (using commit afce2dc):

ERROR: InvalidPropertyFetch - 16:21 - Cannot fetch property on non-object $__fake_var_464 of type string

[weirdan]

but the error on the site is displaying as "of type string". I'm not sure why that happens, or if that's important.)

That's because you need to use @param to annotate parameters, but you used @var instead.

[sapphirecat]

That's because you need to use @param to annotate parameters, but you used @var instead.

Alas, I should have checked it in PhpStorm first. Thanks. I can confirm my actual code uses @param properly.