Misparse of enums in list{}

[bwoebi]

https://psalm.dev/r/04fcfb0955

While @return A::X|A::Y standalone works, putting it in a list{} will misinterpret the first part of the expression up to the first colon as array key of the list instead of recognizing the enum value.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/04fcfb0955

<?php

enum A {
    case X;
    case Y;
    case Z;
}

/**
 * @return list{A::X|A::Y}
 */
function returnsList(int $c): array {
    if ($c) {
        return [A::X];
    }
    return [A::Y];
}

Psalm output (using commit 4b2c698):

ERROR: InvalidDocblock - 12:1 - :: in array key is only allowed for ::class in docblock for returnsList

[danog]

Just wrap the parts: https://psalm.dev/r/61d2d0ec1c

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/61d2d0ec1c

<?php

enum A {
    case X;
    case Y;
    case Z;
}

/**
 * @return list{(A::X)|(A::Y)}
 */
function returnsList(int $c): array {
    if ($c) {
        return [A::X];
    }
    return [A::Y];
}

Psalm output (using commit 4b2c698):

No issues!

[bwoebi]

@danog That seems rather like a workaround than a fix - I think it should stay open?

I see no particular parse conflict here, why it should not be possible to parse that?

[danog]

Yeah that can be fixed!

[weirdan]

The reason for not allowing constants in list keys seems to be somewhat technical. Our type AST for keyed arrays uses native php types (int/string) to represent shape keys (they become actual array kes of TKeyedArray::$properties) rather than Psalm types. Thus, we cannot differentiate between A::B and "A::B" - they both have the same string representation, and we cannot reliably resolve constant values during the scanning phase as referenced classes may not have been scanned yet. And we won't be ever able to use standalone constants (e.g. PHP_VERSION) in shape keys using current syntax as it's ambiguous.

But we should be able to support constants in list value types by backtracking and reinterpreting the part being parsed, as a value type, the same way we can do it currently with list{1}.