remove unneeded lifetimes from drop guards

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

Author: hawkw

tokio-executor/src/global.rs

@@ -3,7 +3,6 @@ use super::{Enter, Executor, SpawnError};
 use futures::{future, Future};
 
 use std::cell::Cell;
-use std::marker::PhantomData;
 
 /// Executes futures on the default executor for the current execution context.
 ///
@@ -23,8 +22,8 @@ pub struct DefaultExecutor {
 /// Ensures that the executor is removed from the thread-local context
 /// when leaving the scope. This handles cases that involve panicking.
 #[derive(Debug)]
-pub struct DefaultGuard<'a> {
-    _lifetime: PhantomData<&'a ()>,
+pub struct DefaultGuard {
+    _p: (),
 }
 
 impl DefaultExecutor {
@@ -183,6 +182,11 @@ where
     T: Executor,
     F: FnOnce(&mut Enter) -> R,
 {
+    unsafe fn hide_lt<'a>(p: *mut (dyn Executor + 'a)) -> *mut (dyn Executor + 'static) {
+        use std::mem;
+        mem::transmute(p)
+    }
+
     EXECUTOR.with(|cell| {
         match cell.get() {
             State::Ready(_) | State::Active => {
@@ -224,7 +228,7 @@ where
 /// # Panics
 ///
 /// This function panics if there already is a default executor set.
-pub fn set_default<'a, T>(executor: T) -> DefaultGuard<'a>
+pub fn set_default<T>(executor: T) -> DefaultGuard
 where
     T: Executor + 'static,
 {
@@ -244,17 +248,10 @@ where
         cell.set(State::Ready(Box::into_raw(executor)));
     });
 
-    DefaultGuard {
-        _lifetime: PhantomData,
-    }
-}
-
-unsafe fn hide_lt<'a>(p: *mut (dyn Executor + 'a)) -> *mut (dyn Executor + 'static) {
-    use std::mem;
-    mem::transmute(p)
+    DefaultGuard { _p: () }
 }
 
-impl<'a> Drop for DefaultGuard<'a> {
+impl Drop for DefaultGuard {
     fn drop(&mut self) {
         let _ = EXECUTOR.try_with(|cell| {
             if let State::Ready(prev) = cell.replace(State::Empty) {

tokio-reactor/src/lib.rs

@@ -68,7 +68,6 @@ use tokio_sync::task::AtomicTask;
 use std::cell::RefCell;
 use std::error::Error;
 use std::io;
-use std::marker::PhantomData;
 use std::mem;
 #[cfg(all(unix, not(target_os = "fuchsia")))]
 use std::os::unix::io::{AsRawFd, RawFd};
@@ -137,8 +136,8 @@ pub type SetDefaultError = SetFallbackError;
 /// Ensure that the default reactor is removed from the thread-local context
 /// when leaving the scope. This handles cases that involve panicking.
 #[derive(Debug)]
-pub struct DefaultGuard<'a> {
-    _lifetime: PhantomData<&'a ()>,
+pub struct DefaultGuard {
+    _p: (),
 }
 
 #[test]
@@ -217,7 +216,7 @@ where
 /// # Panics
 ///
 /// This function panics if there already is a default reactor set.
-pub fn set_default(handle: &Handle) -> DefaultGuard<'_> {
+pub fn set_default(handle: &Handle) -> DefaultGuard {
     CURRENT_REACTOR.with(|current| {
         let mut current = current.borrow_mut();
 
@@ -236,9 +235,7 @@ pub fn set_default(handle: &Handle) -> DefaultGuard<'_> {
 
         *current = Some(handle.clone());
     });
-    DefaultGuard {
-        _lifetime: PhantomData,
-    }
+    DefaultGuard { _p: () }
 }
 
 impl Reactor {
@@ -746,7 +743,7 @@ impl Direction {
     }
 }
 
-impl<'a> Drop for DefaultGuard<'a> {
+impl Drop for DefaultGuard {
     fn drop(&mut self) {
         let _ = CURRENT_REACTOR.try_with(|current| {
             let mut current = current.borrow_mut();

tokio-timer/src/clock/clock.rs

@@ -5,7 +5,6 @@ use tokio_executor::Enter;
 
 use std::cell::RefCell;
 use std::fmt;
-use std::marker::PhantomData;
 use std::sync::Arc;
 use std::time::Instant;
 
@@ -23,8 +22,8 @@ pub struct Clock {
 
 /// A guard that resets the current `Clock` to `None` when dropped.
 #[derive(Debug)]
-pub struct DefaultGuard<'a> {
-    _lifetime: PhantomData<&'a ()>,
+pub struct DefaultGuard {
+    _p: (),
 }
 
 thread_local! {
@@ -131,7 +130,7 @@ where
 /// # Panics
 ///
 /// This function panics if there already is a default clock set.
-pub fn set_default(clock: &Clock) -> DefaultGuard<'_> {
+pub fn set_default(clock: &Clock) -> DefaultGuard {
     CLOCK.with(|cell| {
         assert!(
             cell.borrow().is_none(),
@@ -140,13 +139,11 @@ pub fn set_default(clock: &Clock) -> DefaultGuard<'_> {
 
         *cell.borrow_mut() = Some(clock.clone());
 
-        DefaultGuard {
-            _lifetime: PhantomData,
-        }
+        DefaultGuard { _p: () }
     })
 }
 
-impl<'a> Drop for DefaultGuard<'a> {
+impl Drop for DefaultGuard {
     fn drop(&mut self) {
         let _ = CLOCK.try_with(|cell| cell.borrow_mut().take());
     }

tokio-timer/src/timer/handle.rs

@@ -5,7 +5,6 @@ use tokio_executor::Enter;
 
 use std::cell::RefCell;
 use std::fmt;
-use std::marker::PhantomData;
 use std::sync::{Arc, Weak};
 use std::time::{Duration, Instant};
 
@@ -47,8 +46,8 @@ pub(crate) struct HandlePriv {
 
 /// A guard that resets the current timer to `None` when dropped.
 #[derive(Debug)]
-pub struct DefaultGuard<'a> {
-    _lifetime: PhantomData<&'a ()>,
+pub struct DefaultGuard {
+    _p: (),
 }
 
 thread_local! {
@@ -80,7 +79,7 @@ where
 /// # Panics
 ///
 /// This function panics if there already is a default timer set.
-pub fn set_default(handle: &Handle) -> DefaultGuard<'_> {
+pub fn set_default(handle: &Handle) -> DefaultGuard {
     CURRENT_TIMER.with(|current| {
         let mut current = current.borrow_mut();
 
@@ -96,9 +95,7 @@ pub fn set_default(handle: &Handle) -> DefaultGuard<'_> {
 
         *current = Some(handle.clone());
     });
-    DefaultGuard {
-        _lifetime: PhantomData,
-    }
+    DefaultGuard { _p: () }
 }
 
 impl Handle {
@@ -194,7 +191,7 @@ impl fmt::Debug for HandlePriv {
     }
 }
 
-impl<'a> Drop for DefaultGuard<'a> {
+impl Drop for DefaultGuard {
     fn drop(&mut self) {
         let _ = CURRENT_TIMER.try_with(|current| {
             let mut current = current.borrow_mut();