Drupal Check could not find Drupal root but PHPstan could

[mxr576]

How is drupal-check installed?

• drupal-check is installed using the phar
• drupal-check is installed globally via Composer
• drupal-check is installed globally using consolidation/cgr
• drupal-check is installed as a dependency to my project

Environment:

• OS: Docker
• PHP Version: 7.2
• Drupal core: 8.7.5

Describe the bug
I am working with a monorepo that structure is the following:

Drupal Check tries to do something smart to figure out the Drupal root and the location of the vendor dir but Drupal Finder unable to locate Drupal root in the given structure if I run ./vendor/bin/drupal-check web/modules/contrib/[SYMLINKED_MODULE].
Although, if I call PHPstan directly with the following parameters it works perfectly fine: ./vendor/bin/phpstan analyze -c vendor/mglaman/drupal-check/phpstan/rules_and_deprecations_testing.neon web/modules/contrib/[SYMLINKED_MODULE].

As I can see the reason behind this is that Drupal Check calls Drupal Finder first to figure out the Drupal root to mimic PHPStan's $GLOBALS['autoloaderInWorkingDirectory'] trick. Although, as I described above Drupal Finder is unable to find Drupal root in the given setup this is the reason why Drupal Check fails but PHPstan does not.

Console output
N/A

[mxr576]

I may have a fix for this problem, I just need to verify whether it works with the global installation as well.