The mystery of avoiding circular symlinks in the node_modules directory

[mszmida]

Hello @zkochan,

I would like to thank you very much for your work on creating the pnpm! Good job 👍

I am a new user and like the idea how the pnpm handles the installation of the npm packages. During reading the documentation I spotted some sentences that are not entirely clear for me. Let's take a look at the snippet from the official docs:

Source:
https://pnpm.js.org/symlinked-node-modules-structure

As I marked above, I do not not understand how keeping the package dependencies on the same level as the package itself solves the circular symlinks problem.

This answer also does not give me a lot of explanations:

Source:
https://pnpm.js.org/faq/#what-about-circular-symlinks

This topic is also referenced in this blog article:

Source:
https://pnpm.js.org/blog/2020/05/27/flat-node-modules-is-not-the-only-way

I found this PR where you changed the store structure but I couldn't figure out the store structure before and after these changes:
#524

I don't even know if it was the right place to look for.

My investigation left me with some unanswered questions:

1. In which scenario the circular symlinks problem occured? Could you show the structure of the node_modules directory to visualize this case?
2. Is the circular symlinks problem connected to the store structure? If yes, could you also show the store structure to visualize the problem?

Sorry for a long post 😄

Regards