Strlen as guard for non-empty-string

[ivoba]

Followup ticket for #10056 :

A condition with a Strlen check should be regarded as valid guard for non-empty-string warning.

See: https://psalm.dev/r/bba89100c3

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/bba89100c3

<?php

/** @return non-empty-string */
function getHardcodedString1(): string {
    return 'foo';
}

/** @psalm-check-type $string1 = non-empty-string */
$string1 = getHardcodedString1();

/** @return non-empty-string */
function getHardcodedString2(): string {
	/** @psalm-check-type $string = non-empty-string */
    $string = 'foo';
    
    return $string;
}

/** @psalm-check-type $string2 = non-empty-string */
$string2 = getHardcodedString2();

/** @return non-empty-string */
function getHardcodedString3(): string {
	/** @psalm-check-type STRING = non-empty-string */
    define('STRING', 'foo');
    
    return STRING;
}

/** @psalm-check-type $string3 = non-empty-string */
$string3 = getHardcodedString3();

final class Example
{
    private const FOO = 'foo';
    /** @var non-empty-string */
    private string $bar = 'bar';
    
    /** @return non-empty-string */
    public function getFoo(): string
    {
        return self::FOO;
    }
    
    /** @return non-empty-string */
    public function getBar(): string
    {
        return $this->bar;
    }
}

/** @psalm-check-type $string4 = non-empty-string */
$string4 = (new Example())->getFoo();

/** @psalm-check-type $string5 = non-empty-string */
$string5 = (new Example())->getBar();


$someUserInput = $_GET['foo'] ?? '';
if (is_string($someUserInput) && strlen($someUserInput) > 0) {
    /** @psalm-check-type $string6 = non-empty-string */
    $string6 = $someUserInput;
}

Psalm output (using commit 73ebe22):

ERROR: CheckType - 62:5 - Checked variable $string6 = non-empty-string does not match $string6 = string

[orklah]

Thanks for creating the issue!

If you're interested for looking into it, we basically did the same thing for count on arrays here:

psalm/src/Psalm/Internal/Analyzer/Statements/Expression/AssertionFinder.php

Line 850 in fa644cb

} elseif (self::hasNonEmptyCountCheck($expr)) {

[kkmuffme]

Duplicate of #7387