Annotations - constants as array-key not working

[Chrico]

[!] Note: This issue is a duplicate of #2836 (comment) -but since the #2836 is closed and no reaction, i'd like to push the visibility of the topic.

---

Problem:
As far as i can see, in list<> class constants are working as array-value.
But when using array{}, they are not working as array-key.

Is there any reason why this is not supported? Are there technical restrictions to implement this?

---

Test cases:

✔️ List: https://psalm.dev/r/00af5dfd5f

❌ Array: https://psalm.dev/r/593314e3a1

---

@muglug

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/00af5dfd5f

<?php

class Foo {
    public const MY_KEY = 'x';
}

/**
 * A class constant as list array-value does work and is resolved
 *
 * @return list<Foo::MY_KEY>
 */
function test__arrayValue(): array {
    return [Foo::MY_KEY];
}
/**
 * ...even with "wildcard".
 *
 * @return list<Foo::MY_*>
 */
function test__arrayValueWildcard(): array {
    return [Foo::MY_KEY];
}

Psalm output (using commit 666cc3b):

No issues!

https://psalm.dev/r/593314e3a1

<?php

class Foo {
    public const MY_KEY = 'x';
}

/**
 * A class constant as array-key with "optional" works
 *
 * @return array{Foo::MY_KEY?:string}
 */
function test__optionalArrayKey(): array {
 	return [Foo::MY_KEY => 'foo'];   
}
/**
 * ...but an multidimensional array with class constant as array-key required not work.
 * 
 * @return array{Foo::MY_KEY:string}
 */
function test__requiredArrayKey(): array {
    return [Foo::MY_KEY => 'foo'];
}
/**
 * Same for wildcard class constant as array-key
 *
 * @return array{Foo::MY_*:string}
 */
function test__wildcardArrayKey(): array {
    return [Foo::MY_KEY => 'foo']; 
}

Psalm output (using commit 666cc3b):

ERROR: InvalidReturnStatement - 21:12 - The inferred type 'array{x: string(foo)}' does not match the declared return type 'array{Foo::MY_KEY: string}' for test__requiredArrayKey

ERROR: InvalidReturnType - 18:12 - The declared return type 'array{Foo::MY_KEY: string}' for test__requiredArrayKey is incorrect, got 'array{x: string(foo)}'

ERROR: InvalidReturnStatement - 29:12 - The inferred type 'array{x: string(foo)}' does not match the declared return type 'array{Foo::MY_*: string}' for test__wildcardArrayKey

ERROR: InvalidReturnType - 26:12 - The declared return type 'array{Foo::MY_*: string}' for test__wildcardArrayKey is incorrect, got 'array{x: string(foo)}'

[weirdan]

This https://psalm.dev/r/edc3d9f34b works (but all keys are treated as optional).

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/edc3d9f34b

<?php

class Foo {
    public const MY_KEY = 'x';
}

/**
 * A class constant as array-key with "optional" works
 *
 * @return array<Foo::MY_KEY,string>
 */
function test__optionalArrayKey(): array {
 	return [Foo::MY_KEY => 'foo'];   
}

/**
 * ...but an multidimensional array with class constant as array-key required not work.
 * 
 * @return array<Foo::MY_KEY,string>
 */
function test__requiredArrayKey(): array {
    return [Foo::MY_KEY => 'foo'];
}
/**
 * Same for wildcard class constant as array-key
 *
 * @return array<Foo::MY_*,string>
 */
function test__wildcardArrayKey(): array {
    return [Foo::MY_KEY => 'foo']; 
}

Psalm output (using commit 666cc3b):

No issues!

[muglug]

This shouldn't work – array keys in array{...} annotations must be explicit (they can't be indirect). I've updated Psalm to treat array{SomeClass::CONST: string} as a docblock bug.