Parcel ignoring PeerDependency if dependency has been installed in a library

🐛 bug report

When using experimental scope hoisting the PeerDependency list is ignored for libraries when the dependency is also in node_modules. Any dependencies are included twice in the final bundle.

🎛 Configuration (.babelrc, package.json, cli command)

https://git.dany.dev/dsluijk/parcelpeers

🤔 Expected Behavior

There should be only one entity of a library in the final bundle output.

😯 Current Behavior

Two instances of the same library are included in the bundle, inflating the bundle unnecessary.

💁 Possible Solution

Check if a library is in peerdependencies before adding it into the bundle. As it’s a peer dependency it’s fair to assume another installation will be bundled.

🔦 Context

The library has the dependency both listed as dev as well as peer dependency. This is needed because we need it as a dev dependency for the build step, and as a peer dependency for actual usage of the library.

💻 Code Sample

I’ve created an example project here: https://git.dany.dev/dsluijk/parcelpeers

To reproduce:

1. Clone the repository.
2. Go into the library folder and run yarn + yarn build. This build the library, and also installs preact into node_modules as it’s listed as dev dependency.
3. Exit library and enter app.
4. Install dependencies with yarn, this installs the second installation of preact as it’s listed as a dependency.
5. Build and serve with yarn serve.
6. Go to http://localhost:1234/report.html to view the bundle report. Notice preact is included twice here.

🌍 Your Environment

Software	Version(s)
Parcel	1.12.4
Node	15.1.0
npm/Yarn	Yarn 1.12.4
Operating System	Arch Linux x86_64, 5.9.6-arch1-1

[tripolskypetr]

Hello there! Still waiting for React components library bundling support on Parcel 2…

[michox]

This issue is still occurring, can we reopen this issue, please?