[Bug?]: Yarn ignores peerDependencies in workspace package

[quentez]

Self-service

• I'd be willing to implement a fix

Describe the bug

After upgrading from 4.1.1 to 4.3.1 I'm now getting an error that one of the packages in my Yarn workspace is failing to provide a package that a dependency declares as peer.

But I already have that package in the peerDependencies key of my package.json. It's as if Yarn is ignoring that field. Could it be related to the work done by @clemyan in #6205 ?

Here's the error:

➤ YN0002: │ @baqhub/sdk-expo@workspace:packages/lib-sdk-expo doesn't provide expo (p6ba33), requested by expo-secure-store.

And in the package.json for @baqhub/sdk-expo:

"peerDependencies": {
  "expo": "*",
  "react-native": ">=0.60"
}

To reproduce

1. In a Yarn workspace, add the expo-secure-store to one of the packages.
2. Add expo as a peer dependency to that package.
3. When running yarn, get a warning indicating that the package should provide the peer dependency.

Environment

System:
  OS: macOS 15.0
  CPU: (8) arm64 Apple M1
Binaries:
  Node: 22.3.0 - /private/var/folders/k1/b_tdbtrx26x_m0r_hvsldpsm0000gn/T/xfs-71da02d9/node
  Yarn: 4.3.1 - /private/var/folders/k1/b_tdbtrx26x_m0r_hvsldpsm0000gn/T/xfs-71da02d9/yarn
  npm: 10.8.1 - /opt/homebrew/bin/npm

Additional context

No response

[arcanis]

A workspace has no parent from its general perspective, so it doesn't provide any peer dependency (until it gets used as a dependency of another package). You need to also list expo/react-native as devDependencies (I guess expo already is?).

[quentez]

@arcanis Thank you for taking a look at this!

I'm not sure I fully understand your answer though.

I'm not doing anything at the workspace level, it's only within one of the sub-packages. Shouldn't it be enough to specify expo as peerDependency without having to also add it as dependency/devDependency?

(I'm not calling expo directly, I'm only adding it to satisfy the constraint from the expo-secure-store dependency).

[arcanis]

Workspaces have two perspectives (sets of dependencies):

• As dependencies of another workspace
• As root of the dependency tree (for example when running yarn run from within this workspace's folder)

Even if workspaces depending on @baqhub/sdk-expo declare react-native in their dependencies, the second perspective is still there: if you run a yarn run command from packages/lib-sdk-expo, there will be no "parent package", thus no react-native. That's why listing a peer dependency often means you need a matching dev dependency (we probably should make this clearer).

[quentez]

That makes sense! I appreciate the thorough explanation 🙇‍♂️
And the solution is quite straightforward as well. Not a bug then!

[TheAsda]

Faced the same issue and could not figure it out for a long time. IMHO yarn run is not the most common usage of a package. Clearer error message or some references in documentation would be so much help. With "add to peers" approach it's easy to make sure you have only one copy of a package in your project. Duplicating dev dependencies can lead to multiple versions of a package is workspaces environment if not careful with dependencies management.