Unmet peer dependency warning when the peer dependency is installed at the same time

[fson]

Bug

What is the current behavior?

Installing a dependency and its peer dependency at the same time generates a warning "Unmet peer dependency" even though the peer dependency is installed.

Steps to reproduce:

> mkdir test
> cd test
> yarn init -y
> yarn add react react-dom
yarn add v0.17.10
info No lockfile found.
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
warning Unmet peer dependency "react@^15.4.1".

On the other hand, first running yarn add react and then yarn add react-dom doesn't create any warnings.

What is the expected behavior?

No warnings about peer dependencies should be printed when other packages specified in the add command will satisfy the peer dependencies.

Please mention your node.js, yarn and operating system version.

Node.js v6.9.1
Yarn 0.17.10
macOS 10.12.1

[andreiglingeanu]

Can confirm this.

I've got while doing yarn add babel-plugin-transform-vue-jsx.

warning Unmet peer dependency "babel-helper-vue-jsx-merge-props@^2.0.0".
warning Unmet peer dependency "babel-plugin-syntax-jsx@^6.8.0".

[connesc]

Same here with yarn add request request-promise-native:

warning Unmet peer dependency "request@^2.34".
warning Unmet peer dependency "request@^2.34".

[idibidiart]

Same issue.

[idibidiart]

low priority?

[gaearon]

Would you like to send a PR to fix it?

[idibidiart]

@gaearon

do you have any idea what part(s) of the Yarn code the PR would have to touch (potentially)? :)

[gaearon]

Not really :-). I'd just recommend searching for the error message string and then seeing where it's used.

[andreiglingeanu]

@gaearon Yeah, right here :)

[kamilogorek]

After some debugging, and using yarn add request request-promise-native as a test case, I found that the main issue is this code:

yarn/src/package-linker.js

Line 315 in 4e4075f

const dep = this.resolver.getResolvedPattern(pattern);

this.resolver.getResolvedPattern(pattern)

is expecting a pattern in a very specific form eg. request@^2.79.0, which is available in this.resolver.patterns map.

However, what's passed is just request string, therefore it will always return undefined.

I was able to fix it successfully using this code:

    for (const name in peerDeps) {
      const range = peerDeps[name];
      const packageInfo = this.resolver.getAllInfoForPackageName(name)
      const hasAnyPackageVersion = packageInfo.length !== 0
      const foundDep = packageInfo.find((entry) => this._satisfiesPeerDependency(range, entry.version))

      if (foundDep) {
        ref.addDependencies([`${foundDep.name}@^${foundDep.version}`])
      } else {
        const depError = hasAnyPackageVersion ? 'incorrectPeer' : 'unmetPeer';
        const pkgHuman = `${pkg.name}@${pkg.version}`,
              depHuman = `${name}@${range}`;
        this.reporter.warn(this.reporter.lang(depError, pkgHuman, depHuman));
      }
    }

But this line ref.addDependencies([${foundDep.name}@^${foundDep.version}]) is assuming a carret range, which is not right. I'm not able to pull a specific pattern that I can store using ref.addDependencies.

Any pointers how I should approach it?