[BUG] `npm rebuild` does not rebuild optional dependencies if they are in a nested node_modules folder

Is there an existing issue for this?

• I have searched the existing issues

This issue exists in the latest npm version

• I am using the latest npm

Current Behavior

npm rebuild --foreground-scripts does not execute install script of package-c ❌

Expected Behavior

npm rebuild --foreground-scripts executes install script of package-c (and therefore prints installing package-c!)

Steps To Reproduce

1. In this reproduction repository: https://github.com/pkerschbaum/npm-issue-rebuild-not-working-for-optional-deps-in-deeper-nodemodules
2. Run npm rebuild --foreground-scripts in the root directory of this repo.
   --> package-c not installed

Notes:

The dependency chain is

node-starter
--> dependency: package-a
  --> dependency: package-b
    --> optionalDependency: package-c

And the packages are nested like this (which is a totally valid node_modules structure, and something similar to this happens with pnpm!):

.
├── package.json
└── node_modules/
    └── package-a/
        ├── package.json
        └── node_modules/
            ├── package-b/
            │   └── package.json
            └── node_modules/
                └── package-c/
                    └── package.json

But I found two ways to get a rebuild for package-c:

• In package.json of package-b, if you move package-cfrom optionalDependencies to dependencies (or devDependencies)
• Also, if you move package-c to the root node_modules folder

So what I observed is:

• dependencies and devDependencies are rebuilt as expected
• optionalDependencies are only rebuilt if they reside in the root node_modules folder
• peerDependencies are rebuilt
  • as expected when peerDependenciesMeta.optional is not set or false
  • have the same issue as optionalDependencies when peerDependenciesMeta.optional is true

Environment

• npm: 9.6.4 (but also an issue with 8.19.3)
• Node.js: 16.19.0
• OS Name: Ubuntu 22.04.1 LTS (WSL 2)
• System Model Name: Asus ROG Zephyrus M16 (2022)
• npm config:

; node bin location = /home/pkerschbaum/.nvm/versions/node/v16.19.0/bin/node
; node version = v16.19.0
; npm local prefix = /home/pkerschbaum/workspace/npm-issue-rebuild-not-working-for-optional-deps
; npm version = 9.6.4
; cwd = /home/pkerschbaum/workspace/npm-issue-rebuild-not-working-for-optional-deps
; HOME = /home/pkerschbaum
; Run `npm config ls -l` to show all defaults.

Start by running npm rebuild --foreground-scripts in the linked reproduction repository and inspect how npm traverses nested node_modules entries during rebuild. Trace the handling of optional dependencies; the fix is complete when package-c's install script runs and prints installing package-c! for the reported nested layout.