Uncovered line with array_merge() and require() in PHP 7.4

[BluePsyduck]

Q	A
php-code-coverage version	7.0.10
PHP version	7.4.1
Driver	Xdebug
Xdebug version (if used)	2.9.0
Installation Method	Composer
Usage Method	PHPUnit
PHPUnit version (if used)	8.5.2

I found an issue with the coverage reports when array_merging some configuration files.

<?php
declare(strict_types=1);
namespace FancyNamespace;

class ConfigProvider
{
    public function __invoke(): array
    {
        return array_merge(
            require(__DIR__ . '/foo.php'), 
            require(__DIR__ . '/bar.php'),
        );
    }
}

Note that the files included have simple contents like <?php return ['foo' => 'bar']; each, i.e. the array_merge() can properly do its work.

The coverage report shows that the line with require(foo) is not covered:

Some observations of the issue:

• There must be at least two files included. A single file is correctly covered, more files have only the last require line covered respectively.
• This issue started appearing with PHP 7.4, reports under PHP 7.3 do not show this problem.

It would be nice if you could look into it.

[sebastianbergmann]

CC @derickr

[derickr]

https://bugs.xdebug.org/view.php?id=1733