Merge #1943

1943: Rustier kqueue API r=rtzoeller a=asomers

* Prefer methods instead of functions.
* Create a newtype for a kqueue.
* Document everything.
* Deprecate EVFILT_SENDFILE, because it was never fully implemented upstream.
* Add support to the libc_enum! macro to be able to deprecate variants.

Co-authored-by: Alan Somers <asomers@gmail.com>

Author: bors[bot]

CHANGELOG.md

@@ -24,6 +24,10 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 - With I/O-safe type applied in `pty::OpenptyResult` and `pty::ForkptyResult`,
   users no longer need to manually close the file descriptors in these types.
   ([#1921](https://github.com/nix-rust/nix/pull/1921))
+- `sys::event::{kevent, kevent_ts}` are deprecated in favor of
+  `sys::kevent::Kqueue::kevent`, and `sys::event::kqueue` is deprecated in
+  favor of `sys::kevent::Kqueue::new`.
+  ([#1943](https://github.com/nix-rust/nix/pull/1943))
 
 ### Fixed
 - Fix `SockaddrIn6` bug that was swapping flowinfo and scope_id byte ordering.

src/macros.rs

@@ -132,6 +132,8 @@ macro_rules! libc_enum {
         impl ::std::convert::TryFrom<$repr> for $BitFlags {
             type Error = $crate::Error;
             #[allow(unused_doc_comments)]
+            #[allow(deprecated)]
+            #[allow(unused_attributes)]
             fn try_from(x: $repr) -> $crate::Result<Self> {
                 match x {
                     $($try_froms)*