Description:
------------
It is difficult for me to make this reproducible.
Short notice on the setup:
A local vm with vagrant and php 7.3.16:

PHP 7.3.16-1+ubuntu16.04.1+deb.sury.org+1 (cli) (built: Mar 20 2020 13:51:21) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.16, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.3.16-1+ubuntu16.04.1+deb.sury.org+1, Copyright (c) 1999-2018, by Zend Technologies

That one does *not* have the problem.

Then there is an aws instance that is running the following version:

PHP 7.3.16-1+ubuntu18.04.1+deb.sury.org+1 (cli) (built: Mar 20 2020 13:51:46) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.16, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.3.16-1+ubuntu18.04.1+deb.sury.org+1, Copyright (c) 1999-2018, by Zend Technologies

This one *has* the problem.

The following happens (I also included a little code snippet, although it may be hard to reproduce).

Whenever a typehint "object" is encountered (in my failing case, it is PHPUnit, but it happens on any typehint "object", even in other functions):

 [TypeError] Argument 5 passed to PHPUnit\Framework\MockObject\Invocation::__construct() must be an instance of PHPUnit\Framework\MockObject\object, instance of Mock_MyClient_070b46a8 given, called in /project/vendor/phpunit/phpunit/src/Framework/MockObject/MockClass.php(42) : eval()'d code on line 47  

This is the line that does not pass the typecheck: (PHPUnit 9.0.2)

public function __construct(string $className, string $methodName, array $parameters, string $returnType, object $object, bool $cloneObjects = false, bool $proxiedCall = false)

The 5th parameter seems to be misunderstood to be an "object" of the same namespace, instead of the reserved "object" keyword. (which should be passed by the mock passed in)
I first had this in 7.3.9, and then upgraded to the latest 7.3.16, but the problem still persisted on the AWS instance.

I am not sure if this is a bug or just a configuration issue, but it seems that some versions (I am not sure how they differ) are unable to understand this relatively new typehint which was introduced in php 7.2. I included a little snippet that *might* reproduce it. If you need more info, please tell me, it is just a little hard to get it from the aws instance (which is why I did not go haywire and collected everything beforehand).

The code in the snippet should actually just produce a failure because of different contents that are compared, but throws this on the aws instance:

[TypeError] Argument 1 passed to Test\Namespace1\MyTest::getMyResult() must be an instance of Test\Namespace1\object, instance of stdClass given, called in /project/tests/Test/Namespace1/MyTest.php on line 14

(The line number might differ)  

I hope someone might have an idea how this can fit together and guide me in the right direction. Happy to assist with further input. Good night!



Test script:
---------------
<?php

namespace Test\Namespace1;

use Codeception\TestCase\Test;
use stdClass;

class MyTest extends Test
{
    public function testObjectAnnotation()
    {
        $a = new stdClass();
        $a->c = "1";
        $this->assertEquals('anything', $this->getMyResult($a));
    }

    private function getMyResult(object $anything): string
    {
        return $anything->c;
    }
}


Expected result:
----------------
 MyTest: Object annotation
 Test  tests/Test/Namespace1/MyTest.php:testObjectAnnotation
Failed asserting that two strings are equal.
- Expected | + Actual
@@ @@
-'anything'
+'1'
#1  /project/tests/Test/Namespace1/MyTest.php:14


Actual result:
--------------
[TypeError] Argument 1 passed to Test\Namespace1\MyTest::getMyResult() must be an instance of Test\Namespace1\object, instance of stdClass given, called in /project/tests/Test/Namespace1/MyTest.php on line 14