InvalidReturnStatement for lists with shape inferred from PHP code with conditions

[alies-dev]

Psalm: 5.3.0

list<string> should be a superset of list{0?: string, 1: string}.

https://psalm.dev/r/c1147fc79d

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/c1147fc79d

<?php

/** @return non-empty-list<string> */
function buildListWithOptionalValues(): array {
    $list = [];
    $entropy = random_int(0, 2);
    if ($entropy === 0) {
        $list[] = 'A';
    } elseif ($entropy === 1) {
        $list[] = 'B';
    }

    $list[] = 'C';

    return $list;
}

buildListWithOptionalValues();

Psalm output (using commit 96cb44b):

ERROR: InvalidReturnStatement - 15:12 - The inferred type 'list{0?: 'A'|'B', 1: 'C'}' does not match the declared return type 'non-empty-list<string>' for buildListWithOptionalValues

ERROR: InvalidReturnType - 3:13 - The declared return type 'non-empty-list<string>' for buildListWithOptionalValues is incorrect, got 'list{0?: 'A'|'B', 1: 'C'}'

[danog]

list{0?: string, 1: string} is actually not a valid list type (so the error would be correct, but the type should've also been marked as array), and it shouldn't have been generated in the first place (a list{0: 'A'|'B'|'C', 1?: 'C'} should've been generated instead).

I've already started work to fix this and a number of other issues, it's a bit tricky :)

[boesing]

Not sure if it is worth handling this.

Even if array{0: string, 1: string} would be interpreted as list that would be a flaw, because the array-key order is probably not really handled by psalm.

https://psalm.dev/r/2c3fa92ffa
https://3v4l.org/3FHbY#v8.1.13

Or I am misinterpreting something here. Maybe. Just stumbled upon this and was confused.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/2c3fa92ffa

<?php


/** @return list<string> */
function createListWithTwoStringElements(): array
{
    return ['foo', 'bar'];
}

/** @return array{0:string,1:string} */
function createArrayWithTwoStringElements(): array
{
	return [
    	1 => 'bar',
        0 => 'foo',
    ];
}

var_dump(array_is_list(createListWithTwoStringElements()), array_is_list(createArrayWithTwoStringElements()));

Psalm output (using commit 96cb44b):

ERROR: RedundantCondition - 19:10 - list<string> always contains list<mixed>

ERROR: ForbiddenCode - 19:1 - Unsafe var_dump

[danog]

array{0: string, 1: string} is, correctly, not interpreted as a list, so it's not an issue.

[danog]

Fixed!