Using setters with class-string-map

[weirdan]

I've been experimenting with undocumented class-string-map type, and I think the following (slight modification of the passing test case) should be type-safe: https://psalm.dev/r/53e6c832e1

Related: #4458 (using a class-string-map there could be a valid solution).

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/53e6c832e1

<?php
                        namespace Bar;
     
                        /**
                         * @psalm-consistent-constructor
                         */
                        class Foo {}
     
                        class A {
                            /** @var class-string-map<T as Foo, T> */
                            public static array $map = [];
     
                            /**
                             * @template T as Foo
                             * @param class-string<T> $class
                             * @return T
                             */
                            public function get(string $class) : Foo {
                                if (isset(self::$map[$class])) {
                                    return self::$map[$class];
                                }
                                throw new \RuntimeException();
     

                            }
                            
                            /** @param class-string<Foo> $class */
                            public function set(string $class): void {
                                self::$map[$class] = new $class();
                            }
                        }

Psalm output (using commit 579327a):

ERROR: InvalidPropertyAssignmentValue - 29:33 - Bar\A::$map with declared type 'class-string-map<T as Bar\Foo, T:class-string-map as Bar\Foo>' cannot be assigned type 'non-empty-array<class-string<Bar\Foo>|(class-string<T:class-string-map as Bar\Foo>), Bar\Foo|(T:class-string-map as Bar\Foo)>'

[muglug]

Yeah, when I added class-string-map I said at the time that I wouldn't fix any new issues with it. If you want to have a go here, feel free, but this looks pretty complex.

[ptomulik]

This is interesting:

https://psalm.dev/r/f8a3440139

using if(isset($this->instances[$key])){} somehow makes psalm to not emit the error

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/f8a3440139

<?php

class Container
{
    /**
     * @psalm-var class-string-map<T, T>
     */
    private array $instances = [];

    /**
     * @psalm-template U of object
     * @psalm-param class-string<U> $key
     * @psalm-param U $instance
     */
    public function set(string $key, object $instance): void
    {
        if(isset($this->instances[$key])) {} // <- !!!
        $this->instances[$key] = $instance;
    }
}

Psalm output (using commit c0e757c):

No issues!