MacOSX' RecommendedWatcher (FsEventWatcher) doesn't implement Send

[julienw]

This is misleading because other watchers are Send and so can be moved between threads.

Here is an example of an error I get in MacOS X only:

src/lib.rs:643:9: 643:22 error: the trait bound `*mut libc::c_void: std::marker::Send` is not satisfied [E0277]
src/lib.rs:643         thread::spawn(move || {
                                                                                                          ^~~~~~~~~~~~~
src/lib.rs:643:9: 643:22 help: run `rustc --explain E0277` to see a detailed explanation
src/lib.rs:643:9: 643:22 note: `*mut libc::c_void` cannot be sent between threads safely
src/lib.rs:643:9: 643:22 note: required because it appears within the type `notify::FsEventWatcher`
src/lib.rs:643:9: 643:22 note: required because it appears within the type `FsWatcher`

[julienw]

This is not obvious, but cf::CFMutableArrayRef is an alias to *mut libc::c_void.

[julienw]

I think we could add unsafe impl Send for FsEventWatcher, as it seems safe to pass this pointer accross threads. Not sure for Sync, but I think it would be fine as well because the methods that change states use &mut self.

What do you think ?

If you agree I can write the patch.

[passcod]

Cc @octplane

[octplane]

@julienw that would be nice if you could write the patch. Does that only consist in adding the unsafe.. to the impl ? Would you mind trying to write a test for that too ?

[julienw]

Yes, it would be simply adding the unsafe impl Send//Sync. I can try to write a test :)

[octplane]

Nice 🌅 . Let us know if anything is blocking you.