Remove Copy from PollFd

PollFd implementing Copy makes it easy to accidentally refer to the
wrong object after putting one into an array.

This fixes nix-rust#2630

Author: JonathonReinhart

src/poll.rs

@@ -14,7 +14,7 @@ use crate::Result;
 /// After a call to `poll` or `ppoll`, the events that occurred can be
 /// retrieved by calling [`revents()`](#method.revents) on the `PollFd`.
 #[repr(transparent)]
-#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
 pub struct PollFd<'fd> {
     pollfd: libc::pollfd,
     _fd: std::marker::PhantomData<BorrowedFd<'fd>>,
@@ -61,7 +61,7 @@ impl<'fd> PollFd<'fd> {
 
     /// Returns the events that occurred in the last call to `poll` or `ppoll`.  Will only return
     /// `None` if the kernel provides status flags that Nix does not know about.
-    pub fn revents(self) -> Option<PollFlags> {
+    pub fn revents(&self) -> Option<PollFlags> {
         PollFlags::from_bits(self.pollfd.revents)
     }
 
@@ -71,7 +71,7 @@ impl<'fd> PollFd<'fd> {
     /// Equivalent to `x.revents()? != PollFlags::empty()`.
     ///
     /// This is marginally more efficient than [`PollFd::all`].
-    pub fn any(self) -> Option<bool> {
+    pub fn any(&self) -> Option<bool> {
         Some(self.revents()? != PollFlags::empty())
     }
 
@@ -81,12 +81,12 @@ impl<'fd> PollFd<'fd> {
     /// Equivalent to `x.revents()? & x.events() == x.events()`.
     ///
     /// This is marginally less efficient than [`PollFd::any`].
-    pub fn all(self) -> Option<bool> {
+    pub fn all(&self) -> Option<bool> {
         Some(self.revents()? & self.events() == self.events())
     }
 
     /// The events of interest for this `PollFd`.
-    pub fn events(self) -> PollFlags {
+    pub fn events(&self) -> PollFlags {
         PollFlags::from_bits(self.pollfd.events).unwrap()
     }