Hi, I'd need to understand these advanced Makefile features and I'm not sure if I want to 😊

Putting things after the rule lists their dependencies. A dependency can either be another target, or a file. You're already using this for the 'check' line:

The changes here add two new targets, and list them as dependencies where relevant.

• vendor - when changes detected in 'composer.json' or 'composer.lock' files, then the commands within that target are run: composer install
• composer.lock - because this file doesn't exist in the repository (see .gitignore), make will fail the vendor target without being told how to make this file be created.

Running the cs target before running cs-install results in an error (because the files don't exist). The same is the case for lint or tests where the commands in vendor/bin/ do not yet exist.

Thank you, but:

1. What the composer.json target does? vendor: composer.json composer.lock
2. I don't want to run cs-install every time when I run make cs
3. Is it a coincidence or on purpose that vendor target has the name of the vendor directory?
4. I think that generally make can work on Windows, but I'm pretty sure this syntax breaks that: test -f composer.lock
5. I'd want for make to work the same across all repositories in https://github.com/phpstan and I'm not sure if you're going to update all of them. These updates are also not the priority for me right now so I don't know if I'm going to review them and merge them in timely manner.
6. The flow of vendor isn't ideal in some scenarios - for example for the first run it's going to run composer update and composer install right afterwards.

Because of these many issues and questions and also because I'm not a fan of complexity in the Makefile, I decided not to merge this PR. I work on these projects daily and in my opinion the current experience is okay.

Thanks for taking the time to consider this and for explaining your perspective. I can address all of these issues/questions, but don't want to burden you any further.