Summary of a problem or a feature request

Using a string argument in the function declaration that then is used in array_key_exists with an array where all the key's are string versions of integers will provide the error Call to function array_key_exists() with string and array(123 => 'test') will always evaluate to false.

With phpstan 0.10.5 and php 7.2.9.

Code snippet that reproduces the problem

<?php 

namespace Project\Test;

class TestClass
{
    public function test(string $index)
    {
        $array = [
            "123" => "test"
        ];
        return array_key_exists($index, $array);
    }
}

but if you run

<?php
declare(strict_types = 1);

use Project\Test\TestClass;

require_once __DIR__ . '/vendor/autoload.php';


$test = new TestClass();
var_dump($test->test("123"));

it will log bool(true)

https://phpstan.org/r/e2d1c03a-235d-410a-8966-24bc4987167d

Expected output

There should not be any issue raised.