[BUG](arborist) should not remove global node_modules

[mingc00]

What / Why

For switching different Node.js version, we use symlink for global node_modules.

$ ls -ld /usr/local/lib/node_modules
/usr/local/lib/node_modules -> /var/packages/Node.js_v16/var/node_modules

The global module directory and npm itself is removed after installing global module.

$ npm install -g pino-pretty
npm WARN reify Removing non-directory /usr/local/lib/node_modules

The behavior have been changed from npm/arborist@f2b0cee.

How

Current Behavior

$ npm install -g pino-pretty
npm WARN reify Removing non-directory /usr/local/lib/node_modules

Steps to Reproduce

1. Make global node_modules be symlink.
2. Run npm install -g <any module>
3. The global node_modules is removed.

Expected Behavior

Allow global node_modules be symlink.

[ljharb]

Global modules must not be shared between node versions, for a number of reasons, including that they might be compiled.

[mingc00]

My global node_modules are not shared between node versions.

After switching Node.js version, the node_modules points to different path. That's why our global node_modules is symlink.

[ljharb]

Typically the way this is done with a node version manager is to move the node_modules folder in its entirety, not with a symlink, or to locate it somewhere else. See nvm, nave, and n for the most common node version managers.

[tophf]

How do we move a local per-project node_modules from the project's folder to another drive/folder now?

[ljharb]

@tophf a hard link? generally you don't; a local project, including its node_modules folder, should be kept all on the same drive and in the same location.

[tophf]

How do we make a hardlink for a directory in Windows, which can only make junctions or symlinks?

[wraithgar]

Closing as duplicate of #4358