Bug: "resolutions" trumps `--ignore-optional`

[joscha]

Do you want to request a feature or report a bug?

bug

What is the current behavior?

Currently, when there are resolutions defined, --ignore-optional is ignored and the optional dependencies are installed anyway.

You can test it with a simple package.json:

{
  "name": "test-optional",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "optionalDependencies": {
    "fsevents": "^1.0.0"
  },
  "resolutions": {
    "fsevents": "^1.2.4"
  }
}

on yarn install --ignore-optional the above will lead to fsevents being installed nonetheless.

On Linux (Ubuntu Xenial) for example, this would fail the yarn install due to:

error fsevents@1.2.4: The platform "linux" is incompatible with this module.
error Found incompatible module
info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.

yarn install --ignore-optional works as expected with:

{
  "name": "test-optional",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "optionalDependencies": {
    "fsevents": "^1.0.0"
  }
}

and does not install fsevents.

What is the expected behavior?

No optional dependencies to be installed with --ignore-optional, no matter whether they are mentioned in resolutions or not.

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

yarn 1.7.0
Node 10.5.0
OSX High Sierra and Debian Xenial

[Gudahtt]

I was able to reproduce this problem. If fsevents is an optional dependency (direct or transitive) and is specified in resolutions, the install fails on non-macOS platforms. It even fails without the --ignore-optional flag.

It's not clear on what the expected behavior is for optional dependencies specified in resolutions. Intuitively I'd expect the version set in resolutions to be ignored if the optional package fails to install, but I can't find that specified in the selective-versions-resolutions RFC.

[deftomat]

The same for me with yarn 1.9.4.
I'm pretty sure that the expected behaviour for resolutions is JUST to override a package version. Not to force their installation. Current behaviour is unusable when you have developers with different environments 😞

[wycats]

I hit this problem too, and agree that this behavior is unexpected. Is there even a workaround?

[rally25rs]

Took some time to start digging into this. Trying to understand exactly how resolutions works, but it looks like this line https://github.com/yarnpkg/yarn/blob/master/src/cli/commands/install.js#L286 makes a pkg that is hard-coded to optional: false which is then used to replace another dependency when it matches the resolution.

This happens before the actual dependencies are matched to resolutions, so the above line can't just be altered to match the actual dependency's optional property.

I haven't found the exact spot yet, but I'm guessing that at some point it's taking the fsevents@^1.0.0 optional: true reference and replacing it with the already-resolved fsevents@^1.2.4 optional: false.

If anyone has time to jump in and help, it would be appreciated...

[jasonxia23]

Would like to take a try.

[parris]

I think I found a possible workaround (that may work in some cases - worked for me with chokidar and fsevents) - install with the package's version resolution on a compatible environment. Then remove the resolution and yarn install again. Commit all that. The only problem with this is needing to redo the resolution from time to time.

@joscha I have similar problem. Did you find any good work around for it?

[joscha]

@joscha I have similar problem. Did you find any good work around for it?

I did not unfortunately, sorry.