Don't warn about incompatible optional dependencies

[gaearon]

Currently Yarn behavior matches npm in that it warns about optional dependencies that are incompatible (and thus skipped). fsevents on Windows is a good example of this.

Since the warning is almost never actionable, and looks a bit frightening to beginners, I propose that we downgrade its log level. I'm not sure if Yarn even has a concept of log levels, but I wouldn't want to see this warning unless I'm specifically debugging Yarn itself.

Corresponding npm issue has wide support (although it got autoclosed): npm/npm#11632

Seems like an appropriate use of warn to me.

[wtgtybhertgeghgtwtg]

Wouldn't it be better to fix the thing that is giving the warning instead of just hiding it?

[gaearon]

@wtgtybhertgeghgtwtg

What do you mean by "fix"? As explained in npm/npm#11632, everything is working as intended. Some packages depend on fsevents specifically on macOS (because it offers superior experience) but fall back to other behavior on Windows/Linux. The fact that fsevents is incompatible with Windows should not be surfaced to the users: it's just a platform-specific implementation detail of a dependency. There's nothing actionable for users there (and nothing to be alarmed about).

[wtgtybhertgeghgtwtg]

I would say that requiring a dependency and adding binaries for a specific OS should not be how it works.
I'm sure that there are other packages that make this issue pop up, but fsevents is the most predominate one, getting issues in babel, webpack, your create-react-app, and I sure very soon sane and jest. I think that it would be more productive to find a better file watching solution instead of changing the behavior of a package manager because of the shortcomings of one package.

[gaearon]

If you have an alternative suggestion about what packages using fsevents (or fsevents itself) could do, I'd like to hear that! I don't think there's anything "wrong" about having a package that's OS-specific though. It solves a real problem, and some problems are platform specific.

[bestander]

Looks like opinions are split.
I suppose warning on a non actionable thing could be annoying.
On the other hand similar warnings, e.g. "this module does not work on Node.js < 4", are quite useful.
Is there a settings people can turn on to disable warnings?

@gaearon given this is an open source repo, how about a PR to add a CLI flag to suppress by log level. It would be very incorrect to paper over a downstream issue in the packages you're referencing whether it be a superior computer or just a $35 RPi which can do most of the same stuff.

[gaearon]

@JHabdas

how about a PR to add a CLI flag to suppress by log level

I would have loved to send a PR but, like @bestander, I also work full time on maintaining other open source projects, and unfortunately don’t have the time to work on this particular feature. I raised an issue to discuss whether it is desirable or not.

It would be very incorrect to paper over a downstream issue in the packages you're referencing whether it be a superior computer or just a $35 RPi which can do most of the same stuff.

I don’t understand this comment. I am not suggesting to “paper over a downstream issue”. fsevents is not doing anything wrong. It wants to express that it is only useful on macOS, but doesn’t exist on other systems. Other packages, like webpack, want to express that they’d like to use fsevents on macOS, but want to skip it on other systems. And this is exactly what both yarn and npm are doing.

Everything already works as intended, except that both npm and yarn also print a message that looks scary but doesn’t actually indicate a problem. But there is no reason for the user to be worried because everything works as intended. So my point is it would be nice to stop scaring users when nothing is wrong.

Sorry if I’m not being very clear. I can see now this is more controversial than I expected. Let’s not do this then. I’m not going to die on this hill. 😛

[glen-84]

On the other hand similar warnings, e.g. "this module does not work on Node.js < 4", are quite useful.

... but that's actionable – you can upgrade your version of Node.js.