literal strings as non-empty-string

[thomasvargiu]

Should literal strings be a non-empty-string?

The problem I occurred is the following:

/**
 * @return list<non-empty-string>
 */
function a(): array
{
    // Imaging I have an external declared type like this:
    /** @var array{foo?: list<non-empty-string>} $array */
    $array = [];

    return $array['foo'] ?? ['bar'];
}

https://psalm.dev/r/0cb0b9aa53

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/0cb0b9aa53

<?php

/**
 * @return list<non-empty-string>
 */
function a(): array
{
    // Imaging I have a declared type like this:
    /** @var array{foo?: list<non-empty-string>} $array */
    $array = ['foo' => ['bar']];

    return $array['foo'] ?? ['bar'];
}

Psalm output (using commit ef4afd7):

INFO: LessSpecificReturnStatement - 12:12 - The type 'list<string>' is more general than the declared return type 'list<non-empty-string>' for a

INFO: MoreSpecificReturnType - 4:12 - The declared return type 'list<non-empty-string>' for a is more specific than the inferred return type 'list<string>'

[weirdan]

Should literal strings be a non-empty-string?

Not necessarily. '' is an empty literal string.

It's reconciliation between literal and non-empty strings that should result in non-empty string here, but that doesn't currently happen: https://psalm.dev/r/6d680d86b6

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/6d680d86b6

<?php

/** @return non-empty-string */
function a()
{
    /** @var non-empty-string */
    $s = 'foo';
    if (rand(0, 1)) {
        $r = $s;
    } else {
        /** @psalm-trace $r */
        $r = 'bar';
    }
    // expected non-empty-string, but Psalm infers it as string
    /** @psalm-trace $r */; 
    return $r;
}

Psalm output (using commit ef4afd7):

INFO: Trace - 12:9 - $r: string(bar)

INFO: Trace - 15:27 - $r: string

INFO: LessSpecificReturnStatement - 16:12 - The type 'string' is more general than the declared return type 'non-empty-string' for a

INFO: MoreSpecificReturnType - 3:13 - The declared return type 'non-empty-string' for a is more specific than the inferred return type 'string'

[orklah]

nvm