x/exp/winfsnotify: delete package

[bcmills]

The x/exp/winfsnotify package was moved from the standard library to the x/exp repository in CL 7456047, a little over nine years ago. It has apparently not been touched since then except to add an // import comment in 2014. In 2016, users discussed switching to an externally-maintained alternative (see @nathany's comment in #17244 (comment)).

At least one such alternative, github.com/fsnotify/fsnotify, was still actively maintained at least as of this January (see fsnotify/fsnotify#413), and has a number of volunteers to maintain it going forward.

In the meantime x/exp/winfsnotify has rotted. It has no active owners and its only substantial test is flaky (#49734). The corresponding fsnotify package for Unix platforms was removed in CL 3990, back in 2015.

The packages in the x/exp repository are explicitly experimental. I propose that we declare the x/exp/winfsnotify experiment concluded and delete the package.

[gopherbot]

Change https://go.dev/cl/389615 mentions this issue: winfsnotify: delete package

[rsc]

Given the overwhelming evidence, I think we can make this a direct accept.

[rsc]

No change in consensus, so accepted. 🎉
This issue now tracks the work of implementing the proposal.
— rsc for the proposal review group

[rsc]

@bcmills one think we should consider is checking in a go.mod in that directory first, before the delete, so that if anyone really does need it, they can use it as a separate submodule even if they also need a newer x/exp for other reasons.

[bcmills]

That seems reasonable. Probably we should also add a deprecation notice to the tombstone version, and tag it something like winfsnotify/v0.1.0-deprecated so that it can be resolved from the version list.

[gopherbot]

Change https://go.dev/cl/399834 mentions this issue: winfsnotify: deprecate package and isolate it to its own module

[bcmills]

This is done: the winfsnotify package no longer exists at HEAD, but remains available in module golang.org/x/exp/winfsnotify at its terminal version v0.1.0-deprecated.

I've also confirmed that the documentation for the final, deprecated version is correctly shown at https://pkg.go.dev/golang.org/x/exp/winfsnotify.