Upgrade rust/crates/crossbeam-channel to 0.5.5 am: 45db964b0c

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/crossbeam-channel/+/2137795

Change-Id: Ie70d25054e4d9f1943fc9bc9ae84e1ff0b2e1ee6
Signed-off-by: Automerger Merge Worker <[email protected]>
diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index f15a046..1ea95d0 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,6 +1,6 @@
 {
   "git": {
-    "sha1": "f9cec068fa94bced547a66289cd288dca58c2e83"
+    "sha1": "16769892dc5e1ba14c8ea14e92e85f442e25f4aa"
   },
   "path_in_vcs": "crossbeam-channel"
 }
\ No newline at end of file
diff --git a/Android.bp b/Android.bp
index a5821d8..740fcd8 100644
--- a/Android.bp
+++ b/Android.bp
@@ -47,7 +47,7 @@
     host_supported: true,
     crate_name: "crossbeam_channel",
     cargo_env_compat: true,
-    cargo_pkg_version: "0.5.2",
+    cargo_pkg_version: "0.5.5",
     srcs: ["src/lib.rs"],
     edition: "2018",
     features: [
@@ -59,4 +59,8 @@
         "libcfg_if",
         "libcrossbeam_utils",
     ],
+    apex_available: [
+        "//apex_available:platform",
+        "//apex_available:anyapex",
+    ],
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6bfd923..2f627cf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,22 @@
+# Version 0.5.5
+
+- Replace Spinlock with Mutex. (#835)
+
+# Version 0.5.4
+
+- Workaround a bug in upstream related to TLS access on AArch64 Linux. (#802)
+
+# Version 0.5.3
+
+**Note:** This release has been yanked. See [#802](https://github.com/crossbeam-rs/crossbeam/issues/802) for details.
+
+- Fix panic on very large timeout. (#798)
+
 # Version 0.5.2
 
-- Fix stacked borrows violations. (#763, #764)
+**Note:** This release has been yanked. See [#802](https://github.com/crossbeam-rs/crossbeam/issues/802) for details.
+
+- Fix stacked borrows violations when `-Zmiri-tag-raw-pointers` is enabled. (#763, #764)
 
 # Version 0.5.1
 
@@ -22,6 +38,8 @@
 
 # Version 0.4.3
 
+**Note:** This release has been yanked. See [GHSA-v5m7-53cv-f3hx](https://github.com/crossbeam-rs/crossbeam/security/advisories/GHSA-v5m7-53cv-f3hx) for details.
+
 - Change license to "MIT OR Apache-2.0".
 
 # Version 0.4.2
diff --git a/Cargo.lock b/Cargo.lock
index feb6e75..cd6eb05 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -10,7 +10,7 @@
 
 [[package]]
 name = "crossbeam-channel"
-version = "0.5.2"
+version = "0.5.5"
 dependencies = [
  "cfg-if",
  "crossbeam-utils",
@@ -21,19 +21,19 @@
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.6"
+version = "0.8.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cfcae03edb34f947e64acdb1c33ec169824e20657e9ecb61cef6c8c74dcb8120"
+checksum = "8ff1f980957787286a554052d03c7aee98d99cc32e09f6d45f0a814133c87978"
 dependencies = [
  "cfg-if",
- "lazy_static",
+ "once_cell",
 ]
 
 [[package]]
 name = "getrandom"
-version = "0.2.3"
+version = "0.2.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7fcd999463524c52659517fe2cea98493cfe485d10565e7b0fb07dbba7ad2753"
+checksum = "4eb1a864a501629691edf6c15a593b7a51eebaa1e8468e9ddc623de7c9b58ec6"
 dependencies = [
  "cfg-if",
  "libc",
@@ -50,16 +50,10 @@
 ]
 
 [[package]]
-name = "lazy_static"
-version = "1.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
-
-[[package]]
 name = "libc"
-version = "0.2.112"
+version = "0.2.126"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1b03d17f364a3a042d5e5d46b053bbbf82c92c9430c592dd4c064dc6ee997125"
+checksum = "349d5a591cd28b49e1d1037471617a32ddcda5731b99419008085f72d5a53836"
 
 [[package]]
 name = "num_cpus"
@@ -72,6 +66,12 @@
 ]
 
 [[package]]
+name = "once_cell"
+version = "1.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7709cef83f0c1f58f666e746a08b21e0085f7440fa6a29cc194d68aac97a4225"
+
+[[package]]
 name = "ppv-lite86"
 version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -79,14 +79,13 @@
 
 [[package]]
 name = "rand"
-version = "0.8.4"
+version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2e7573632e6454cf6b99d7aac4ccca54be06da05aca2ef7423d22d27d4d4bcd8"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
 dependencies = [
  "libc",
  "rand_chacha",
  "rand_core",
- "rand_hc",
 ]
 
 [[package]]
@@ -109,19 +108,10 @@
 ]
 
 [[package]]
-name = "rand_hc"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d51e9f596de227fda2ea6c84607f5558e196eeaf43c986b724ba4fb8fdf497e7"
-dependencies = [
- "rand_core",
-]
-
-[[package]]
 name = "signal-hook"
-version = "0.3.13"
+version = "0.3.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "647c97df271007dcea485bb74ffdb57f2e683f1306c854f468a0c244badabf2d"
+checksum = "a253b5e89e2698464fc26b545c9edceb338e18a89effeeecfea192c3025be29d"
 dependencies = [
  "libc",
  "signal-hook-registry",
@@ -138,6 +128,6 @@
 
 [[package]]
 name = "wasi"
-version = "0.10.2+wasi-snapshot-preview1"
+version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
diff --git a/Cargo.toml b/Cargo.toml
index 87a889f..c02f859 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,13 +13,25 @@
 edition = "2018"
 rust-version = "1.36"
 name = "crossbeam-channel"
-version = "0.5.2"
+version = "0.5.5"
 description = "Multi-producer multi-consumer channels for message passing"
 homepage = "https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-channel"
-keywords = ["channel", "mpmc", "select", "golang", "message"]
-categories = ["algorithms", "concurrency", "data-structures"]
+readme = "README.md"
+keywords = [
+    "channel",
+    "mpmc",
+    "select",
+    "golang",
+    "message",
+]
+categories = [
+    "algorithms",
+    "concurrency",
+    "data-structures",
+]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/crossbeam-rs/crossbeam"
+
 [dependencies.cfg-if]
 version = "1"
 
@@ -27,6 +39,7 @@
 version = "0.8"
 optional = true
 default-features = false
+
 [dev-dependencies.num_cpus]
 version = "1.13.0"
 
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index 640a808..344092c 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -4,7 +4,7 @@
 # - Update CHANGELOG.md
 # - Update README.md
 # - Create "crossbeam-channel-X.Y.Z" git tag
-version = "0.5.2"
+version = "0.5.5"
 edition = "2018"
 rust-version = "1.36"
 license = "MIT OR Apache-2.0"
diff --git a/METADATA b/METADATA
index 6cbb05f..8146f87 100644
--- a/METADATA
+++ b/METADATA
@@ -7,13 +7,13 @@
   }
   url {
     type: ARCHIVE
-    value: "https://static.crates.io/crates/crossbeam-channel/crossbeam-channel-0.5.2.crate"
+    value: "https://static.crates.io/crates/crossbeam-channel/crossbeam-channel-0.5.5.crate"
   }
-  version: "0.5.2"
+  version: "0.5.5"
   license_type: NOTICE
   last_upgrade_date {
     year: 2022
-    month: 3
-    day: 1
+    month: 6
+    day: 28
   }
 }
diff --git a/src/channel.rs b/src/channel.rs
index 8988235..800fe63 100644
--- a/src/channel.rs
+++ b/src/channel.rs
@@ -14,6 +14,7 @@
 };
 use crate::flavors;
 use crate::select::{Operation, SelectHandle, Token};
+use crate::utils;
 
 /// Creates a channel of unbounded capacity.
 ///
@@ -232,6 +233,8 @@
 ///
 /// Using a `never` channel to optionally add a timeout to [`select!`]:
 ///
+/// [`select!`]: crate::select!
+///
 /// ```
 /// use std::thread;
 /// use std::time::Duration;
@@ -297,7 +300,7 @@
 /// let ms = |ms| Duration::from_millis(ms);
 ///
 /// // Returns `true` if `a` and `b` are very close `Instant`s.
-/// let eq = |a, b| a + ms(50) > b && b + ms(50) > a;
+/// let eq = |a, b| a + ms(65) > b && b + ms(65) > a;
 ///
 /// let start = Instant::now();
 /// let r = tick(ms(100));
@@ -471,7 +474,7 @@
     /// );
     /// ```
     pub fn send_timeout(&self, msg: T, timeout: Duration) -> Result<(), SendTimeoutError<T>> {
-        self.send_deadline(msg, Instant::now() + timeout)
+        self.send_deadline(msg, utils::convert_timeout_to_deadline(timeout))
     }
 
     /// Waits for a message to be sent into the channel, but only until a given deadline.
@@ -861,7 +864,7 @@
     /// );
     /// ```
     pub fn recv_timeout(&self, timeout: Duration) -> Result<T, RecvTimeoutError> {
-        self.recv_deadline(Instant::now() + timeout)
+        self.recv_deadline(utils::convert_timeout_to_deadline(timeout))
     }
 
     /// Waits for a message to be received from the channel, but only before a given deadline.
diff --git a/src/err.rs b/src/err.rs
index 578acc6..18cb830 100644
--- a/src/err.rs
+++ b/src/err.rs
@@ -308,7 +308,6 @@
 
 impl TryRecvError {
     /// Returns `true` if the receive operation failed because the channel is empty.
-    #[allow(clippy::trivially_copy_pass_by_ref)]
     pub fn is_empty(&self) -> bool {
         match self {
             TryRecvError::Empty => true,
@@ -317,7 +316,6 @@
     }
 
     /// Returns `true` if the receive operation failed because the channel is disconnected.
-    #[allow(clippy::trivially_copy_pass_by_ref)]
     pub fn is_disconnected(&self) -> bool {
         match self {
             TryRecvError::Disconnected => true,
@@ -347,7 +345,6 @@
 
 impl RecvTimeoutError {
     /// Returns `true` if the receive operation timed out.
-    #[allow(clippy::trivially_copy_pass_by_ref)]
     pub fn is_timeout(&self) -> bool {
         match self {
             RecvTimeoutError::Timeout => true,
@@ -356,7 +353,6 @@
     }
 
     /// Returns `true` if the receive operation failed because the channel is disconnected.
-    #[allow(clippy::trivially_copy_pass_by_ref)]
     pub fn is_disconnected(&self) -> bool {
         match self {
             RecvTimeoutError::Disconnected => true,
diff --git a/src/flavors/array.rs b/src/flavors/array.rs
index 871768c..73557d3 100644
--- a/src/flavors/array.rs
+++ b/src/flavors/array.rs
@@ -9,7 +9,6 @@
 //!   - <https://docs.google.com/document/d/1yIAYmbvL3JxOKOjuCyon7JhW4cSv1wy5hC0ApeGMV9s/pub>
 
 use std::cell::UnsafeCell;
-use std::marker::PhantomData;
 use std::mem::MaybeUninit;
 use std::ptr;
 use std::sync::atomic::{self, AtomicUsize, Ordering};
@@ -33,7 +32,7 @@
 
 /// The token type for the array flavor.
 #[derive(Debug)]
-pub struct ArrayToken {
+pub(crate) struct ArrayToken {
     /// Slot to read from or write to.
     slot: *const u8,
 
@@ -72,7 +71,7 @@
     tail: CachePadded<AtomicUsize>,
 
     /// The buffer holding slots.
-    buffer: *mut Slot<T>,
+    buffer: Box<[Slot<T>]>,
 
     /// The channel capacity.
     cap: usize,
@@ -88,9 +87,6 @@
 
     /// Receivers waiting while the channel is empty and not disconnected.
     receivers: SyncWaker,
-
-    /// Indicates that dropping a `Channel<T>` may drop values of type `T`.
-    _marker: PhantomData<T>,
 }
 
 impl<T> Channel<T> {
@@ -109,18 +105,15 @@
 
         // Allocate a buffer of `cap` slots initialized
         // with stamps.
-        let buffer = {
-            let boxed: Box<[Slot<T>]> = (0..cap)
-                .map(|i| {
-                    // Set the stamp to `{ lap: 0, mark: 0, index: i }`.
-                    Slot {
-                        stamp: AtomicUsize::new(i),
-                        msg: UnsafeCell::new(MaybeUninit::uninit()),
-                    }
-                })
-                .collect();
-            Box::into_raw(boxed) as *mut Slot<T>
-        };
+        let buffer: Box<[Slot<T>]> = (0..cap)
+            .map(|i| {
+                // Set the stamp to `{ lap: 0, mark: 0, index: i }`.
+                Slot {
+                    stamp: AtomicUsize::new(i),
+                    msg: UnsafeCell::new(MaybeUninit::uninit()),
+                }
+            })
+            .collect();
 
         Channel {
             buffer,
@@ -131,7 +124,6 @@
             tail: CachePadded::new(AtomicUsize::new(tail)),
             senders: SyncWaker::new(),
             receivers: SyncWaker::new(),
-            _marker: PhantomData,
         }
     }
 
@@ -163,7 +155,8 @@
             let lap = tail & !(self.one_lap - 1);
 
             // Inspect the corresponding slot.
-            let slot = unsafe { &*self.buffer.add(index) };
+            debug_assert!(index < self.buffer.len());
+            let slot = unsafe { self.buffer.get_unchecked(index) };
             let stamp = slot.stamp.load(Ordering::Acquire);
 
             // If the tail and the stamp match, we may attempt to push.
@@ -245,7 +238,8 @@
             let lap = head & !(self.one_lap - 1);
 
             // Inspect the corresponding slot.
-            let slot = unsafe { &*self.buffer.add(index) };
+            debug_assert!(index < self.buffer.len());
+            let slot = unsafe { self.buffer.get_unchecked(index) };
             let stamp = slot.stamp.load(Ordering::Acquire);
 
             // If the the stamp is ahead of the head by 1, we may attempt to pop.
@@ -475,7 +469,6 @@
     }
 
     /// Returns the capacity of the channel.
-    #[allow(clippy::unnecessary_wraps)] // This is intentional.
     pub(crate) fn capacity(&self) -> Option<usize> {
         Some(self.cap)
     }
@@ -528,10 +521,24 @@
 impl<T> Drop for Channel<T> {
     fn drop(&mut self) {
         // Get the index of the head.
-        let hix = self.head.load(Ordering::Relaxed) & (self.mark_bit - 1);
+        let head = *self.head.get_mut();
+        let tail = *self.tail.get_mut();
+
+        let hix = head & (self.mark_bit - 1);
+        let tix = tail & (self.mark_bit - 1);
+
+        let len = if hix < tix {
+            tix - hix
+        } else if hix > tix {
+            self.cap - hix + tix
+        } else if (tail & !self.mark_bit) == head {
+            0
+        } else {
+            self.cap
+        };
 
         // Loop over all slots that hold a message and drop them.
-        for i in 0..self.len() {
+        for i in 0..len {
             // Compute the index of the next slot holding a message.
             let index = if hix + i < self.cap {
                 hix + i
@@ -540,23 +547,12 @@
             };
 
             unsafe {
-                let p = {
-                    let slot = &mut *self.buffer.add(index);
-                    let msg = &mut *slot.msg.get();
-                    msg.as_mut_ptr()
-                };
-                p.drop_in_place();
+                debug_assert!(index < self.buffer.len());
+                let slot = self.buffer.get_unchecked_mut(index);
+                let msg = &mut *slot.msg.get();
+                msg.as_mut_ptr().drop_in_place();
             }
         }
-
-        // Finally, deallocate the buffer, but don't run any destructors.
-        unsafe {
-            // Create a slice from the buffer to make
-            // a fat pointer. Then, use Box::from_raw
-            // to deallocate it.
-            let ptr = std::slice::from_raw_parts_mut(self.buffer, self.cap) as *mut [Slot<T>];
-            Box::from_raw(ptr);
-        }
     }
 }
 
diff --git a/src/flavors/at.rs b/src/flavors/at.rs
index 4581edb..ca5ee60 100644
--- a/src/flavors/at.rs
+++ b/src/flavors/at.rs
@@ -35,7 +35,7 @@
     /// Creates a channel that delivers a message after a certain duration of time.
     #[inline]
     pub(crate) fn new_timeout(dur: Duration) -> Self {
-        Self::new_deadline(Instant::now() + dur)
+        Self::new_deadline(utils::convert_timeout_to_deadline(dur))
     }
 
     /// Attempts to receive a message without blocking.
@@ -142,7 +142,6 @@
     }
 
     /// Returns the capacity of the channel.
-    #[allow(clippy::unnecessary_wraps)] // This is intentional.
     #[inline]
     pub(crate) fn capacity(&self) -> Option<usize> {
         Some(1)
diff --git a/src/flavors/list.rs b/src/flavors/list.rs
index 5056aa4..9bda6d1 100644
--- a/src/flavors/list.rs
+++ b/src/flavors/list.rs
@@ -126,7 +126,7 @@
 
 /// The token type for the list flavor.
 #[derive(Debug)]
-pub struct ListToken {
+pub(crate) struct ListToken {
     /// The block of slots.
     block: *const u8,
 
@@ -634,9 +634,9 @@
 
 impl<T> Drop for Channel<T> {
     fn drop(&mut self) {
-        let mut head = self.head.index.load(Ordering::Relaxed);
-        let mut tail = self.tail.index.load(Ordering::Relaxed);
-        let mut block = self.head.block.load(Ordering::Relaxed);
+        let mut head = *self.head.index.get_mut();
+        let mut tail = *self.tail.index.get_mut();
+        let mut block = *self.head.block.get_mut();
 
         // Erase the lower bits.
         head &= !((1 << SHIFT) - 1);
@@ -654,7 +654,7 @@
                     p.as_mut_ptr().drop_in_place();
                 } else {
                     // Deallocate the block and move to the next one.
-                    let next = (*block).next.load(Ordering::Relaxed);
+                    let next = *(*block).next.get_mut();
                     drop(Box::from_raw(block));
                     block = next;
                 }
diff --git a/src/flavors/never.rs b/src/flavors/never.rs
index 1951e96..277a61d 100644
--- a/src/flavors/never.rs
+++ b/src/flavors/never.rs
@@ -65,7 +65,6 @@
     }
 
     /// Returns the capacity of the channel.
-    #[allow(clippy::unnecessary_wraps)] // This is intentional.
     #[inline]
     pub(crate) fn capacity(&self) -> Option<usize> {
         Some(0)
diff --git a/src/flavors/tick.rs b/src/flavors/tick.rs
index d4b1f6c..4201b6e 100644
--- a/src/flavors/tick.rs
+++ b/src/flavors/tick.rs
@@ -10,6 +10,7 @@
 use crate::context::Context;
 use crate::err::{RecvTimeoutError, TryRecvError};
 use crate::select::{Operation, SelectHandle, Token};
+use crate::utils;
 
 /// Result of a receive operation.
 pub(crate) type TickToken = Option<Instant>;
@@ -28,7 +29,7 @@
     #[inline]
     pub(crate) fn new(dur: Duration) -> Self {
         Channel {
-            delivery_time: AtomicCell::new(Instant::now() + dur),
+            delivery_time: AtomicCell::new(utils::convert_timeout_to_deadline(dur)),
             duration: dur,
         }
     }
@@ -112,7 +113,6 @@
     }
 
     /// Returns the capacity of the channel.
-    #[allow(clippy::unnecessary_wraps)] // This is intentional.
     #[inline]
     pub(crate) fn capacity(&self) -> Option<usize> {
         Some(1)
diff --git a/src/flavors/zero.rs b/src/flavors/zero.rs
index 4afbd8f..31e62af 100644
--- a/src/flavors/zero.rs
+++ b/src/flavors/zero.rs
@@ -5,6 +5,7 @@
 use std::cell::UnsafeCell;
 use std::marker::PhantomData;
 use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Mutex;
 use std::time::Instant;
 use std::{fmt, ptr};
 
@@ -13,11 +14,10 @@
 use crate::context::Context;
 use crate::err::{RecvTimeoutError, SendTimeoutError, TryRecvError, TrySendError};
 use crate::select::{Operation, SelectHandle, Selected, Token};
-use crate::utils::Spinlock;
 use crate::waker::Waker;
 
 /// A pointer to a packet.
-pub struct ZeroToken(*mut ());
+pub(crate) struct ZeroToken(*mut ());
 
 impl Default for ZeroToken {
     fn default() -> Self {
@@ -95,7 +95,7 @@
 /// Zero-capacity channel.
 pub(crate) struct Channel<T> {
     /// Inner representation of the channel.
-    inner: Spinlock<Inner>,
+    inner: Mutex<Inner>,
 
     /// Indicates that dropping a `Channel<T>` may drop values of type `T`.
     _marker: PhantomData<T>,
@@ -105,7 +105,7 @@
     /// Constructs a new zero-capacity channel.
     pub(crate) fn new() -> Self {
         Channel {
-            inner: Spinlock::new(Inner {
+            inner: Mutex::new(Inner {
                 senders: Waker::new(),
                 receivers: Waker::new(),
                 is_disconnected: false,
@@ -126,7 +126,7 @@
 
     /// Attempts to reserve a slot for sending a message.
     fn start_send(&self, token: &mut Token) -> bool {
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
 
         // If there's a waiting receiver, pair up with it.
         if let Some(operation) = inner.receivers.try_select() {
@@ -155,7 +155,7 @@
 
     /// Attempts to pair up with a sender.
     fn start_recv(&self, token: &mut Token) -> bool {
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
 
         // If there's a waiting sender, pair up with it.
         if let Some(operation) = inner.senders.try_select() {
@@ -198,7 +198,7 @@
     /// Attempts to send a message into the channel.
     pub(crate) fn try_send(&self, msg: T) -> Result<(), TrySendError<T>> {
         let token = &mut Token::default();
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
 
         // If there's a waiting receiver, pair up with it.
         if let Some(operation) = inner.receivers.try_select() {
@@ -222,7 +222,7 @@
         deadline: Option<Instant>,
     ) -> Result<(), SendTimeoutError<T>> {
         let token = &mut Token::default();
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
 
         // If there's a waiting receiver, pair up with it.
         if let Some(operation) = inner.receivers.try_select() {
@@ -254,12 +254,12 @@
             match sel {
                 Selected::Waiting => unreachable!(),
                 Selected::Aborted => {
-                    self.inner.lock().senders.unregister(oper).unwrap();
+                    self.inner.lock().unwrap().senders.unregister(oper).unwrap();
                     let msg = unsafe { packet.msg.get().replace(None).unwrap() };
                     Err(SendTimeoutError::Timeout(msg))
                 }
                 Selected::Disconnected => {
-                    self.inner.lock().senders.unregister(oper).unwrap();
+                    self.inner.lock().unwrap().senders.unregister(oper).unwrap();
                     let msg = unsafe { packet.msg.get().replace(None).unwrap() };
                     Err(SendTimeoutError::Disconnected(msg))
                 }
@@ -275,7 +275,7 @@
     /// Attempts to receive a message without blocking.
     pub(crate) fn try_recv(&self) -> Result<T, TryRecvError> {
         let token = &mut Token::default();
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
 
         // If there's a waiting sender, pair up with it.
         if let Some(operation) = inner.senders.try_select() {
@@ -292,7 +292,7 @@
     /// Receives a message from the channel.
     pub(crate) fn recv(&self, deadline: Option<Instant>) -> Result<T, RecvTimeoutError> {
         let token = &mut Token::default();
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
 
         // If there's a waiting sender, pair up with it.
         if let Some(operation) = inner.senders.try_select() {
@@ -325,11 +325,21 @@
             match sel {
                 Selected::Waiting => unreachable!(),
                 Selected::Aborted => {
-                    self.inner.lock().receivers.unregister(oper).unwrap();
+                    self.inner
+                        .lock()
+                        .unwrap()
+                        .receivers
+                        .unregister(oper)
+                        .unwrap();
                     Err(RecvTimeoutError::Timeout)
                 }
                 Selected::Disconnected => {
-                    self.inner.lock().receivers.unregister(oper).unwrap();
+                    self.inner
+                        .lock()
+                        .unwrap()
+                        .receivers
+                        .unregister(oper)
+                        .unwrap();
                     Err(RecvTimeoutError::Disconnected)
                 }
                 Selected::Operation(_) => {
@@ -345,7 +355,7 @@
     ///
     /// Returns `true` if this call disconnected the channel.
     pub(crate) fn disconnect(&self) -> bool {
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
 
         if !inner.is_disconnected {
             inner.is_disconnected = true;
@@ -363,7 +373,6 @@
     }
 
     /// Returns the capacity of the channel.
-    #[allow(clippy::unnecessary_wraps)] // This is intentional.
     pub(crate) fn capacity(&self) -> Option<usize> {
         Some(0)
     }
@@ -397,7 +406,7 @@
     fn register(&self, oper: Operation, cx: &Context) -> bool {
         let packet = Box::into_raw(Packet::<T>::empty_on_heap());
 
-        let mut inner = self.0.inner.lock();
+        let mut inner = self.0.inner.lock().unwrap();
         inner
             .receivers
             .register_with_packet(oper, packet as *mut (), cx);
@@ -406,7 +415,7 @@
     }
 
     fn unregister(&self, oper: Operation) {
-        if let Some(operation) = self.0.inner.lock().receivers.unregister(oper) {
+        if let Some(operation) = self.0.inner.lock().unwrap().receivers.unregister(oper) {
             unsafe {
                 drop(Box::from_raw(operation.packet as *mut Packet<T>));
             }
@@ -419,18 +428,18 @@
     }
 
     fn is_ready(&self) -> bool {
-        let inner = self.0.inner.lock();
+        let inner = self.0.inner.lock().unwrap();
         inner.senders.can_select() || inner.is_disconnected
     }
 
     fn watch(&self, oper: Operation, cx: &Context) -> bool {
-        let mut inner = self.0.inner.lock();
+        let mut inner = self.0.inner.lock().unwrap();
         inner.receivers.watch(oper, cx);
         inner.senders.can_select() || inner.is_disconnected
     }
 
     fn unwatch(&self, oper: Operation) {
-        let mut inner = self.0.inner.lock();
+        let mut inner = self.0.inner.lock().unwrap();
         inner.receivers.unwatch(oper);
     }
 }
@@ -447,7 +456,7 @@
     fn register(&self, oper: Operation, cx: &Context) -> bool {
         let packet = Box::into_raw(Packet::<T>::empty_on_heap());
 
-        let mut inner = self.0.inner.lock();
+        let mut inner = self.0.inner.lock().unwrap();
         inner
             .senders
             .register_with_packet(oper, packet as *mut (), cx);
@@ -456,7 +465,7 @@
     }
 
     fn unregister(&self, oper: Operation) {
-        if let Some(operation) = self.0.inner.lock().senders.unregister(oper) {
+        if let Some(operation) = self.0.inner.lock().unwrap().senders.unregister(oper) {
             unsafe {
                 drop(Box::from_raw(operation.packet as *mut Packet<T>));
             }
@@ -469,18 +478,18 @@
     }
 
     fn is_ready(&self) -> bool {
-        let inner = self.0.inner.lock();
+        let inner = self.0.inner.lock().unwrap();
         inner.receivers.can_select() || inner.is_disconnected
     }
 
     fn watch(&self, oper: Operation, cx: &Context) -> bool {
-        let mut inner = self.0.inner.lock();
+        let mut inner = self.0.inner.lock().unwrap();
         inner.senders.watch(oper, cx);
         inner.receivers.can_select() || inner.is_disconnected
     }
 
     fn unwatch(&self, oper: Operation) {
-        let mut inner = self.0.inner.lock();
+        let mut inner = self.0.inner.lock().unwrap();
         inner.senders.unwatch(oper);
     }
 }
diff --git a/src/select.rs b/src/select.rs
index 6103ef4..57d67a3 100644
--- a/src/select.rs
+++ b/src/select.rs
@@ -22,12 +22,13 @@
 // This is a private API that is used by the select macro.
 #[derive(Debug, Default)]
 pub struct Token {
-    pub at: flavors::at::AtToken,
-    pub array: flavors::array::ArrayToken,
-    pub list: flavors::list::ListToken,
-    pub never: flavors::never::NeverToken,
-    pub tick: flavors::tick::TickToken,
-    pub zero: flavors::zero::ZeroToken,
+    pub(crate) at: flavors::at::AtToken,
+    pub(crate) array: flavors::array::ArrayToken,
+    pub(crate) list: flavors::list::ListToken,
+    #[allow(dead_code)]
+    pub(crate) never: flavors::never::NeverToken,
+    pub(crate) tick: flavors::tick::TickToken,
+    pub(crate) zero: flavors::zero::ZeroToken,
 }
 
 /// Identifier associated with an operation by a specific thread on a specific channel.
@@ -486,7 +487,7 @@
     handles: &mut [(&'a dyn SelectHandle, usize, *const u8)],
     timeout: Duration,
 ) -> Result<SelectedOperation<'a>, SelectTimeoutError> {
-    select_deadline(handles, Instant::now() + timeout)
+    select_deadline(handles, utils::convert_timeout_to_deadline(timeout))
 }
 
 /// Blocks until a given deadline, or until one of the operations becomes ready and selects it.
@@ -518,6 +519,8 @@
 /// The [`select!`] macro is a convenience wrapper around `Select`. However, it cannot select over a
 /// dynamically created list of channel operations.
 ///
+/// [`select!`]: crate::select!
+///
 /// Once a list of operations has been built with `Select`, there are two different ways of
 /// proceeding:
 ///
@@ -1042,7 +1045,7 @@
     /// }
     /// ```
     pub fn ready_timeout(&mut self, timeout: Duration) -> Result<usize, ReadyTimeoutError> {
-        self.ready_deadline(Instant::now() + timeout)
+        self.ready_deadline(utils::convert_timeout_to_deadline(timeout))
     }
 
     /// Blocks until a given deadline, or until one of the operations becomes ready.
diff --git a/src/select_macro.rs b/src/select_macro.rs
index f8b247e..efe0ae4 100644
--- a/src/select_macro.rs
+++ b/src/select_macro.rs
@@ -121,18 +121,7 @@
     };
     // Only one case remains.
     (@list
-        ($case:ident ($($args:tt)*) $(-> $res:pat)* => $body:expr)
-        ($($head:tt)*)
-    ) => {
-        $crate::crossbeam_channel_internal!(
-            @list
-            ()
-            ($($head)* $case ($($args)*) $(-> $res)* => { $body },)
-        )
-    };
-    // Accept a trailing comma at the end of the list.
-    (@list
-        ($case:ident ($($args:tt)*) $(-> $res:pat)* => $body:expr,)
+        ($case:ident ($($args:tt)*) $(-> $res:pat)* => $body:expr $(,)?)
         ($($head:tt)*)
     ) => {
         $crate::crossbeam_channel_internal!(
@@ -373,20 +362,7 @@
 
     // Check the format of a recv case.
     (@case
-        (recv($r:expr) -> $res:pat => $body:tt, $($tail:tt)*)
-        ($($cases:tt)*)
-        $default:tt
-    ) => {
-        $crate::crossbeam_channel_internal!(
-            @case
-            ($($tail)*)
-            ($($cases)* recv($r) -> $res => $body,)
-            $default
-        )
-    };
-    // Allow trailing comma...
-    (@case
-        (recv($r:expr,) -> $res:pat => $body:tt, $($tail:tt)*)
+        (recv($r:expr $(,)?) -> $res:pat => $body:tt, $($tail:tt)*)
         ($($cases:tt)*)
         $default:tt
     ) => {
@@ -428,20 +404,7 @@
 
     // Check the format of a send case.
     (@case
-        (send($s:expr, $m:expr) -> $res:pat => $body:tt, $($tail:tt)*)
-        ($($cases:tt)*)
-        $default:tt
-    ) => {
-        $crate::crossbeam_channel_internal!(
-            @case
-            ($($tail)*)
-            ($($cases)* send($s, $m) -> $res => $body,)
-            $default
-        )
-    };
-    // Allow trailing comma...
-    (@case
-        (send($s:expr, $m:expr,) -> $res:pat => $body:tt, $($tail:tt)*)
+        (send($s:expr, $m:expr $(,)?) -> $res:pat => $body:tt, $($tail:tt)*)
         ($($cases:tt)*)
         $default:tt
     ) => {
@@ -496,20 +459,7 @@
     };
     // Check the format of a default case with timeout.
     (@case
-        (default($timeout:expr) => $body:tt, $($tail:tt)*)
-        $cases:tt
-        ()
-    ) => {
-        $crate::crossbeam_channel_internal!(
-            @case
-            ($($tail)*)
-            $cases
-            (default($timeout) => $body,)
-        )
-    };
-    // Allow trailing comma...
-    (@case
-        (default($timeout:expr,) => $body:tt, $($tail:tt)*)
+        (default($timeout:expr $(,)?) => $body:tt, $($tail:tt)*)
         $cases:tt
         ()
     ) => {
@@ -1043,7 +993,7 @@
 /// An operation is considered to be ready if it doesn't have to block. Note that it is ready even
 /// when it will simply return an error because the channel is disconnected.
 ///
-/// The `select` macro is a convenience wrapper around [`Select`]. However, it cannot select over a
+/// The `select!` macro is a convenience wrapper around [`Select`]. However, it cannot select over a
 /// dynamically created list of channel operations.
 ///
 /// [`Select`]: super::Select
diff --git a/src/utils.rs b/src/utils.rs
index 557b6a0..9f14c8e 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,14 +1,10 @@
 //! Miscellaneous utilities.
 
-use std::cell::{Cell, UnsafeCell};
+use std::cell::Cell;
 use std::num::Wrapping;
-use std::ops::{Deref, DerefMut};
-use std::sync::atomic::{AtomicBool, Ordering};
 use std::thread;
 use std::time::{Duration, Instant};
 
-use crossbeam_utils::Backoff;
-
 /// Randomly shuffles a slice.
 pub(crate) fn shuffle<T>(v: &mut [T]) {
     let len = v.len();
@@ -61,52 +57,10 @@
     }
 }
 
-/// A simple spinlock.
-pub(crate) struct Spinlock<T> {
-    flag: AtomicBool,
-    value: UnsafeCell<T>,
-}
-
-impl<T> Spinlock<T> {
-    /// Returns a new spinlock initialized with `value`.
-    pub(crate) fn new(value: T) -> Spinlock<T> {
-        Spinlock {
-            flag: AtomicBool::new(false),
-            value: UnsafeCell::new(value),
-        }
-    }
-
-    /// Locks the spinlock.
-    pub(crate) fn lock(&self) -> SpinlockGuard<'_, T> {
-        let backoff = Backoff::new();
-        while self.flag.swap(true, Ordering::Acquire) {
-            backoff.snooze();
-        }
-        SpinlockGuard { parent: self }
-    }
-}
-
-/// A guard holding a spinlock locked.
-pub(crate) struct SpinlockGuard<'a, T> {
-    parent: &'a Spinlock<T>,
-}
-
-impl<T> Drop for SpinlockGuard<'_, T> {
-    fn drop(&mut self) {
-        self.parent.flag.store(false, Ordering::Release);
-    }
-}
-
-impl<T> Deref for SpinlockGuard<'_, T> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        unsafe { &*self.parent.value.get() }
-    }
-}
-
-impl<T> DerefMut for SpinlockGuard<'_, T> {
-    fn deref_mut(&mut self) -> &mut T {
-        unsafe { &mut *self.parent.value.get() }
+// https://github.com/crossbeam-rs/crossbeam/issues/795
+pub(crate) fn convert_timeout_to_deadline(timeout: Duration) -> Instant {
+    match Instant::now().checked_add(timeout) {
+        Some(deadline) => deadline,
+        None => Instant::now() + Duration::from_secs(86400 * 365 * 30),
     }
 }
diff --git a/src/waker.rs b/src/waker.rs
index dec73a9..7eb58ba 100644
--- a/src/waker.rs
+++ b/src/waker.rs
@@ -2,11 +2,11 @@
 
 use std::ptr;
 use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Mutex;
 use std::thread::{self, ThreadId};
 
 use crate::context::Context;
 use crate::select::{Operation, Selected};
-use crate::utils::Spinlock;
 
 /// Represents a thread blocked on a specific channel operation.
 pub(crate) struct Entry {
@@ -77,26 +77,32 @@
     /// Attempts to find another thread's entry, select the operation, and wake it up.
     #[inline]
     pub(crate) fn try_select(&mut self) -> Option<Entry> {
-        self.selectors
-            .iter()
-            .position(|selector| {
-                // Does the entry belong to a different thread?
-                selector.cx.thread_id() != current_thread_id()
-                    && selector // Try selecting this operation.
-                        .cx
-                        .try_select(Selected::Operation(selector.oper))
-                        .is_ok()
-                    && {
-                        // Provide the packet.
-                        selector.cx.store_packet(selector.packet);
-                        // Wake the thread up.
-                        selector.cx.unpark();
-                        true
-                    }
-            })
-            // Remove the entry from the queue to keep it clean and improve
-            // performance.
-            .map(|pos| self.selectors.remove(pos))
+        if self.selectors.is_empty() {
+            None
+        } else {
+            let thread_id = current_thread_id();
+
+            self.selectors
+                .iter()
+                .position(|selector| {
+                    // Does the entry belong to a different thread?
+                    selector.cx.thread_id() != thread_id
+                        && selector // Try selecting this operation.
+                            .cx
+                            .try_select(Selected::Operation(selector.oper))
+                            .is_ok()
+                        && {
+                            // Provide the packet.
+                            selector.cx.store_packet(selector.packet);
+                            // Wake the thread up.
+                            selector.cx.unpark();
+                            true
+                        }
+                })
+                // Remove the entry from the queue to keep it clean and improve
+                // performance.
+                .map(|pos| self.selectors.remove(pos))
+        }
     }
 
     /// Returns `true` if there is an entry which can be selected by the current thread.
@@ -170,7 +176,7 @@
 /// This is a simple wrapper around `Waker` that internally uses a mutex for synchronization.
 pub(crate) struct SyncWaker {
     /// The inner `Waker`.
-    inner: Spinlock<Waker>,
+    inner: Mutex<Waker>,
 
     /// `true` if the waker is empty.
     is_empty: AtomicBool,
@@ -181,7 +187,7 @@
     #[inline]
     pub(crate) fn new() -> Self {
         SyncWaker {
-            inner: Spinlock::new(Waker::new()),
+            inner: Mutex::new(Waker::new()),
             is_empty: AtomicBool::new(true),
         }
     }
@@ -189,7 +195,7 @@
     /// Registers the current thread with an operation.
     #[inline]
     pub(crate) fn register(&self, oper: Operation, cx: &Context) {
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
         inner.register(oper, cx);
         self.is_empty.store(
             inner.selectors.is_empty() && inner.observers.is_empty(),
@@ -200,7 +206,7 @@
     /// Unregisters an operation previously registered by the current thread.
     #[inline]
     pub(crate) fn unregister(&self, oper: Operation) -> Option<Entry> {
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
         let entry = inner.unregister(oper);
         self.is_empty.store(
             inner.selectors.is_empty() && inner.observers.is_empty(),
@@ -213,7 +219,7 @@
     #[inline]
     pub(crate) fn notify(&self) {
         if !self.is_empty.load(Ordering::SeqCst) {
-            let mut inner = self.inner.lock();
+            let mut inner = self.inner.lock().unwrap();
             if !self.is_empty.load(Ordering::SeqCst) {
                 inner.try_select();
                 inner.notify();
@@ -228,7 +234,7 @@
     /// Registers an operation waiting to be ready.
     #[inline]
     pub(crate) fn watch(&self, oper: Operation, cx: &Context) {
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
         inner.watch(oper, cx);
         self.is_empty.store(
             inner.selectors.is_empty() && inner.observers.is_empty(),
@@ -239,7 +245,7 @@
     /// Unregisters an operation waiting to be ready.
     #[inline]
     pub(crate) fn unwatch(&self, oper: Operation) {
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
         inner.unwatch(oper);
         self.is_empty.store(
             inner.selectors.is_empty() && inner.observers.is_empty(),
@@ -250,7 +256,7 @@
     /// Notifies all threads that the channel is disconnected.
     #[inline]
     pub(crate) fn disconnect(&self) {
-        let mut inner = self.inner.lock();
+        let mut inner = self.inner.lock().unwrap();
         inner.disconnect();
         self.is_empty.store(
             inner.selectors.is_empty() && inner.observers.is_empty(),
diff --git a/tests/array.rs b/tests/array.rs
index bb2cebe..de843cd 100644
--- a/tests/array.rs
+++ b/tests/array.rs
@@ -1,7 +1,5 @@
 //! Tests for the array channel flavor.
 
-#![cfg(not(miri))] // TODO: many assertions failed due to Miri is slow
-
 use std::any::Any;
 use std::sync::atomic::AtomicUsize;
 use std::sync::atomic::Ordering;
@@ -254,7 +252,13 @@
 
 #[test]
 fn len() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
     const COUNT: usize = 25_000;
+    #[cfg(miri)]
+    const CAP: usize = 50;
+    #[cfg(not(miri))]
     const CAP: usize = 1000;
 
     let (s, r) = bounded(CAP);
@@ -347,6 +351,9 @@
 
 #[test]
 fn spsc() {
+    #[cfg(miri)]
+    const COUNT: usize = 100;
+    #[cfg(not(miri))]
     const COUNT: usize = 100_000;
 
     let (s, r) = bounded(3);
@@ -369,6 +376,9 @@
 
 #[test]
 fn mpmc() {
+    #[cfg(miri)]
+    const COUNT: usize = 100;
+    #[cfg(not(miri))]
     const COUNT: usize = 25_000;
     const THREADS: usize = 4;
 
@@ -401,6 +411,9 @@
 
 #[test]
 fn stress_oneshot() {
+    #[cfg(miri)]
+    const COUNT: usize = 100;
+    #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
     for _ in 0..COUNT {
@@ -416,6 +429,9 @@
 
 #[test]
 fn stress_iter() {
+    #[cfg(miri)]
+    const COUNT: usize = 100;
+    #[cfg(not(miri))]
     const COUNT: usize = 100_000;
 
     let (request_s, request_r) = bounded(1);
@@ -483,7 +499,14 @@
 
 #[test]
 fn drops() {
+    #[cfg(miri)]
+    const RUNS: usize = 10;
+    #[cfg(not(miri))]
     const RUNS: usize = 100;
+    #[cfg(miri)]
+    const STEPS: usize = 100;
+    #[cfg(not(miri))]
+    const STEPS: usize = 10_000;
 
     static DROPS: AtomicUsize = AtomicUsize::new(0);
 
@@ -499,7 +522,7 @@
     let mut rng = thread_rng();
 
     for _ in 0..RUNS {
-        let steps = rng.gen_range(0..10_000);
+        let steps = rng.gen_range(0..STEPS);
         let additional = rng.gen_range(0..50);
 
         DROPS.store(0, Ordering::SeqCst);
@@ -509,12 +532,16 @@
             scope.spawn(|_| {
                 for _ in 0..steps {
                     r.recv().unwrap();
+                    #[cfg(miri)]
+                    std::thread::yield_now(); // https://github.com/rust-lang/miri/issues/1388
                 }
             });
 
             scope.spawn(|_| {
                 for _ in 0..steps {
                     s.send(DropCounter).unwrap();
+                    #[cfg(miri)]
+                    std::thread::yield_now(); // https://github.com/rust-lang/miri/issues/1388
                 }
             });
         })
@@ -533,6 +560,9 @@
 
 #[test]
 fn linearizable() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
     const COUNT: usize = 25_000;
     const THREADS: usize = 4;
 
@@ -553,6 +583,9 @@
 
 #[test]
 fn fairness() {
+    #[cfg(miri)]
+    const COUNT: usize = 100;
+    #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
     let (s1, r1) = bounded::<()>(COUNT);
@@ -575,6 +608,9 @@
 
 #[test]
 fn fairness_duplicates() {
+    #[cfg(miri)]
+    const COUNT: usize = 100;
+    #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
     let (s, r) = bounded::<()>(COUNT);
@@ -619,6 +655,9 @@
 
 #[test]
 fn channel_through_channel() {
+    #[cfg(miri)]
+    const COUNT: usize = 100;
+    #[cfg(not(miri))]
     const COUNT: usize = 1000;
 
     type T = Box<dyn Any + Send>;
@@ -654,3 +693,56 @@
     })
     .unwrap();
 }
+
+#[test]
+fn panic_on_drop() {
+    struct Msg1<'a>(&'a mut bool);
+    impl Drop for Msg1<'_> {
+        fn drop(&mut self) {
+            if *self.0 && !std::thread::panicking() {
+                panic!("double drop");
+            } else {
+                *self.0 = true;
+            }
+        }
+    }
+
+    struct Msg2<'a>(&'a mut bool);
+    impl Drop for Msg2<'_> {
+        fn drop(&mut self) {
+            if *self.0 {
+                panic!("double drop");
+            } else {
+                *self.0 = true;
+                panic!("first drop");
+            }
+        }
+    }
+
+    // normal
+    let (s, r) = bounded(2);
+    let (mut a, mut b) = (false, false);
+    s.send(Msg1(&mut a)).unwrap();
+    s.send(Msg1(&mut b)).unwrap();
+    drop(s);
+    drop(r);
+    assert!(a);
+    assert!(b);
+
+    // panic on drop
+    let (s, r) = bounded(2);
+    let (mut a, mut b) = (false, false);
+    s.send(Msg2(&mut a)).unwrap();
+    s.send(Msg2(&mut b)).unwrap();
+    drop(s);
+    let res = std::panic::catch_unwind(move || {
+        drop(r);
+    });
+    assert_eq!(
+        *res.unwrap_err().downcast_ref::<&str>().unwrap(),
+        "first drop"
+    );
+    assert!(a);
+    // Elements after the panicked element will leak.
+    assert!(!b);
+}
diff --git a/tests/golang.rs b/tests/golang.rs
index 05d67f6..6a46c03 100644
--- a/tests/golang.rs
+++ b/tests/golang.rs
@@ -15,12 +15,12 @@
 use std::any::Any;
 use std::cell::Cell;
 use std::collections::HashMap;
-use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
+use std::sync::atomic::{AtomicI32, AtomicUsize, Ordering::SeqCst};
 use std::sync::{Arc, Condvar, Mutex};
 use std::thread;
 use std::time::Duration;
 
-use crossbeam_channel::{bounded, select, tick, unbounded, Receiver, Select, Sender};
+use crossbeam_channel::{bounded, never, select, tick, unbounded, Receiver, Select, Sender};
 
 fn ms(ms: u64) -> Duration {
     Duration::from_millis(ms)
@@ -32,7 +32,13 @@
 
 struct ChanInner<T> {
     s: Option<Sender<T>>,
-    r: Receiver<T>,
+    r: Option<Receiver<T>>,
+    // Receiver to use when r is None (Go blocks on receiving from nil)
+    nil_r: Receiver<T>,
+    // Sender to use when s is None (Go blocks on sending to nil)
+    nil_s: Sender<T>,
+    // Hold this receiver to prevent nil sender channel from disconnection
+    _nil_sr: Receiver<T>,
 }
 
 impl<T> Clone for Chan<T> {
@@ -57,35 +63,53 @@
     }
 
     fn try_recv(&self) -> Option<T> {
-        let r = self.inner.lock().unwrap().r.clone();
+        let r = self.inner.lock().unwrap().r.as_ref().unwrap().clone();
         r.try_recv().ok()
     }
 
     fn recv(&self) -> Option<T> {
-        let r = self.inner.lock().unwrap().r.clone();
+        let r = self.inner.lock().unwrap().r.as_ref().unwrap().clone();
         r.recv().ok()
     }
 
-    fn close(&self) {
+    fn close_s(&self) {
         self.inner
             .lock()
             .unwrap()
             .s
             .take()
-            .expect("channel already closed");
+            .expect("channel sender already closed");
+    }
+
+    fn close_r(&self) {
+        self.inner
+            .lock()
+            .unwrap()
+            .r
+            .take()
+            .expect("channel receiver already closed");
+    }
+
+    fn has_rx(&self) -> bool {
+        self.inner.lock().unwrap().r.is_some()
+    }
+
+    fn has_tx(&self) -> bool {
+        self.inner.lock().unwrap().s.is_some()
     }
 
     fn rx(&self) -> Receiver<T> {
-        self.inner.lock().unwrap().r.clone()
+        let inner = self.inner.lock().unwrap();
+        match inner.r.as_ref() {
+            None => inner.nil_r.clone(),
+            Some(r) => r.clone(),
+        }
     }
 
     fn tx(&self) -> Sender<T> {
-        match self.inner.lock().unwrap().s.as_ref() {
-            None => {
-                let (s, r) = bounded(0);
-                std::mem::forget(r);
-                s
-            }
+        let inner = self.inner.lock().unwrap();
+        match inner.s.as_ref() {
+            None => inner.nil_s.clone(),
             Some(s) => s.clone(),
         }
     }
@@ -110,17 +134,32 @@
 
 fn make<T>(cap: usize) -> Chan<T> {
     let (s, r) = bounded(cap);
+    let (nil_s, _nil_sr) = bounded(0);
     Chan {
-        inner: Arc::new(Mutex::new(ChanInner { s: Some(s), r })),
+        inner: Arc::new(Mutex::new(ChanInner {
+            s: Some(s),
+            r: Some(r),
+            nil_r: never(),
+            nil_s,
+            _nil_sr,
+        })),
     }
 }
 
 fn make_unbounded<T>() -> Chan<T> {
     let (s, r) = unbounded();
+    let (nil_s, _nil_sr) = bounded(0);
     Chan {
-        inner: Arc::new(Mutex::new(ChanInner { s: Some(s), r })),
+        inner: Arc::new(Mutex::new(ChanInner {
+            s: Some(s),
+            r: Some(r),
+            nil_r: never(),
+            nil_s,
+            _nil_sr,
+        })),
     }
 }
+
 #[derive(Clone)]
 struct WaitGroup(Arc<WaitGroupInner>);
 
@@ -199,14 +238,6 @@
 }
 
 macro_rules! go {
-    (@parse ref $v:ident, $($tail:tt)*) => {{
-        let ref $v = $v;
-        go!(@parse $($tail)*)
-    }};
-    (@parse move $v:ident, $($tail:tt)*) => {{
-        let $v = $v;
-        go!(@parse $($tail)*)
-    }};
     (@parse $v:ident, $($tail:tt)*) => {{
         let $v = $v.clone();
         go!(@parse $($tail)*)
@@ -240,10 +271,10 @@
     const ITERATIONS: i32 = 10_000;
 
     fn sender(n: i32, c1: Chan<i32>, c2: Chan<i32>, c3: Chan<i32>, c4: Chan<i32>) {
-        defer! { c1.close() }
-        defer! { c2.close() }
-        defer! { c3.close() }
-        defer! { c4.close() }
+        defer! { c1.close_s() }
+        defer! { c2.close_s() }
+        defer! { c3.close_s() }
+        defer! { c4.close_s() }
 
         for i in 0..n {
             select! {
@@ -292,7 +323,7 @@
             done.recv();
             done.recv();
             done.recv();
-            cmux.close();
+            cmux.close_s();
         });
         recver(cmux);
     }
@@ -697,7 +728,7 @@
     use super::*;
 
     #[cfg(miri)]
-    const N: i32 = 1000;
+    const N: i32 = 200;
     #[cfg(not(miri))]
     const N: i32 = 100000;
 
@@ -892,6 +923,9 @@
             2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83,
             89, 97,
         ];
+        #[cfg(miri)]
+        let a = &a[..10];
+
         for item in a.iter() {
             let x = primes.recv().unwrap();
             if x != *item {
@@ -929,6 +963,11 @@
         #[cfg(not(miri))]
         const N: i32 = 200;
 
+        #[cfg(miri)]
+        const MESSAGES_COUNT: i32 = 20;
+        #[cfg(not(miri))]
+        const MESSAGES_COUNT: i32 = 100;
+
         for cap in 0..N {
             {
                 // Ensure that receive from empty chan blocks.
@@ -999,7 +1038,7 @@
                 for i in 0..cap {
                     c.send(i);
                 }
-                c.close();
+                c.close_s();
 
                 for i in 0..cap {
                     let v = c.recv();
@@ -1027,7 +1066,7 @@
                 });
 
                 thread::sleep(ms(1));
-                c.close();
+                c.close_s();
 
                 if !done.recv().unwrap() {
                     panic!();
@@ -1035,15 +1074,15 @@
             }
 
             {
-                // Send 100 integers,
+                // Send many integers,
                 // ensure that we receive them non-corrupted in FIFO order.
                 let c = make::<i32>(cap as usize);
                 go!(c, {
-                    for i in 0..100 {
+                    for i in 0..MESSAGES_COUNT {
                         c.send(i);
                     }
                 });
-                for i in 0..100 {
+                for i in 0..MESSAGES_COUNT {
                     if c.recv() != Some(i) {
                         panic!();
                     }
@@ -1051,11 +1090,11 @@
 
                 // Same, but using recv2.
                 go!(c, {
-                    for i in 0..100 {
+                    for i in 0..MESSAGES_COUNT {
                         c.send(i);
                     }
                 });
-                for i in 0..100 {
+                for i in 0..MESSAGES_COUNT {
                     if c.recv() != Some(i) {
                         panic!();
                     }
@@ -1082,7 +1121,7 @@
                 }
             });
 
-            c.close();
+            c.close_s();
             c.recv();
             t.join().unwrap();
         }
@@ -1149,7 +1188,7 @@
                 done.send(true);
             });
 
-            c2.close();
+            c2.close_s();
             select! {
                 recv(c1.rx()) -> _ => {}
                 default => {}
@@ -1378,7 +1417,7 @@
             );
         }
 
-        done.close();
+        done.close_s();
         wg.wait();
     }
 
@@ -1481,9 +1520,9 @@
                 *expect.lock().unwrap() += v;
                 q.send(v);
             }
-            q.close();
+            q.close_s();
             wg.wait();
-            r.close();
+            r.close_s();
         });
 
         let mut n = 0;
@@ -1541,8 +1580,504 @@
 }
 
 // https://github.com/golang/go/blob/master/test/ken/chan.go
+#[cfg(not(miri))] // Miri is too slow
 mod chan {
-    // TODO
+
+    use super::*;
+
+    const MESSAGES_PER_CHANEL: u32 = 76;
+    const MESSAGES_RANGE_LEN: u32 = 100;
+    const END: i32 = 10000;
+
+    struct ChanWithVals {
+        chan: Chan<i32>,
+        /// Next value to send
+        sv: Arc<AtomicI32>,
+        /// Next value to receive
+        rv: Arc<AtomicI32>,
+    }
+
+    struct Totals {
+        /// Total sent messages
+        tots: u32,
+        /// Total received messages
+        totr: u32,
+    }
+
+    struct Context {
+        nproc: Arc<Mutex<i32>>,
+        cval: Arc<Mutex<i32>>,
+        tot: Arc<Mutex<Totals>>,
+        nc: ChanWithVals,
+        randx: Arc<Mutex<i32>>,
+    }
+
+    impl ChanWithVals {
+        fn with_capacity(capacity: usize) -> Self {
+            ChanWithVals {
+                chan: make(capacity),
+                sv: Arc::new(AtomicI32::new(0)),
+                rv: Arc::new(AtomicI32::new(0)),
+            }
+        }
+
+        fn closed() -> Self {
+            let ch = ChanWithVals::with_capacity(0);
+            ch.chan.close_r();
+            ch.chan.close_s();
+            ch
+        }
+
+        fn rv(&self) -> i32 {
+            self.rv.load(SeqCst)
+        }
+
+        fn sv(&self) -> i32 {
+            self.sv.load(SeqCst)
+        }
+
+        fn send(&mut self, tot: &Mutex<Totals>) -> bool {
+            {
+                let mut tot = tot.lock().unwrap();
+                tot.tots += 1
+            }
+            let esv = expect(self.sv(), self.sv());
+            self.sv.store(esv, SeqCst);
+            if self.sv() == END {
+                self.chan.close_s();
+                return true;
+            }
+            false
+        }
+
+        fn recv(&mut self, v: i32, tot: &Mutex<Totals>) -> bool {
+            {
+                let mut tot = tot.lock().unwrap();
+                tot.totr += 1
+            }
+            let erv = expect(self.rv(), v);
+            self.rv.store(erv, SeqCst);
+            if self.rv() == END {
+                self.chan.close_r();
+                return true;
+            }
+            false
+        }
+    }
+
+    impl Clone for ChanWithVals {
+        fn clone(&self) -> Self {
+            ChanWithVals {
+                chan: self.chan.clone(),
+                sv: self.sv.clone(),
+                rv: self.rv.clone(),
+            }
+        }
+    }
+
+    impl Context {
+        fn nproc(&self) -> &Mutex<i32> {
+            self.nproc.as_ref()
+        }
+
+        fn cval(&self) -> &Mutex<i32> {
+            self.cval.as_ref()
+        }
+
+        fn tot(&self) -> &Mutex<Totals> {
+            self.tot.as_ref()
+        }
+
+        fn randx(&self) -> &Mutex<i32> {
+            self.randx.as_ref()
+        }
+    }
+
+    impl Clone for Context {
+        fn clone(&self) -> Self {
+            Context {
+                nproc: self.nproc.clone(),
+                cval: self.cval.clone(),
+                tot: self.tot.clone(),
+                nc: self.nc.clone(),
+                randx: self.randx.clone(),
+            }
+        }
+    }
+
+    fn nrand(n: i32, randx: &Mutex<i32>) -> i32 {
+        let mut randx = randx.lock().unwrap();
+        *randx += 10007;
+        if *randx >= 1000000 {
+            *randx -= 1000000
+        }
+        *randx % n
+    }
+
+    fn change_nproc(adjust: i32, nproc: &Mutex<i32>) -> i32 {
+        let mut nproc = nproc.lock().unwrap();
+        *nproc += adjust;
+        *nproc
+    }
+
+    fn mkchan(c: usize, n: usize, cval: &Mutex<i32>) -> Vec<ChanWithVals> {
+        let mut ca = Vec::<ChanWithVals>::with_capacity(n);
+        let mut cval = cval.lock().unwrap();
+        for _ in 0..n {
+            *cval += MESSAGES_RANGE_LEN as i32;
+            let chl = ChanWithVals::with_capacity(c);
+            chl.sv.store(*cval, SeqCst);
+            chl.rv.store(*cval, SeqCst);
+            ca.push(chl);
+        }
+        ca
+    }
+
+    fn expect(v: i32, v0: i32) -> i32 {
+        if v == v0 {
+            return if v % MESSAGES_RANGE_LEN as i32 == MESSAGES_PER_CHANEL as i32 - 1 {
+                END
+            } else {
+                v + 1
+            };
+        }
+        panic!("got {}, expected {}", v, v0 + 1);
+    }
+
+    fn send(mut c: ChanWithVals, ctx: Context) {
+        loop {
+            for _ in 0..=nrand(10, ctx.randx()) {
+                thread::yield_now();
+            }
+            c.chan.tx().send(c.sv()).unwrap();
+            if c.send(ctx.tot()) {
+                break;
+            }
+        }
+        change_nproc(-1, ctx.nproc());
+    }
+
+    fn recv(mut c: ChanWithVals, ctx: Context) {
+        loop {
+            for _ in (0..nrand(10, ctx.randx())).rev() {
+                thread::yield_now();
+            }
+            let v = c.chan.rx().recv().unwrap();
+            if c.recv(v, ctx.tot()) {
+                break;
+            }
+        }
+        change_nproc(-1, ctx.nproc());
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn sel(
+        mut r0: ChanWithVals,
+        mut r1: ChanWithVals,
+        mut r2: ChanWithVals,
+        mut r3: ChanWithVals,
+        mut s0: ChanWithVals,
+        mut s1: ChanWithVals,
+        mut s2: ChanWithVals,
+        mut s3: ChanWithVals,
+        ctx: Context,
+    ) {
+        let mut a = 0; // local chans running
+
+        if r0.chan.has_rx() {
+            a += 1;
+        }
+        if r1.chan.has_rx() {
+            a += 1;
+        }
+        if r2.chan.has_rx() {
+            a += 1;
+        }
+        if r3.chan.has_rx() {
+            a += 1;
+        }
+        if s0.chan.has_tx() {
+            a += 1;
+        }
+        if s1.chan.has_tx() {
+            a += 1;
+        }
+        if s2.chan.has_tx() {
+            a += 1;
+        }
+        if s3.chan.has_tx() {
+            a += 1;
+        }
+
+        loop {
+            for _ in 0..=nrand(5, ctx.randx()) {
+                thread::yield_now();
+            }
+            select! {
+                recv(r0.chan.rx()) -> v => if r0.recv(v.unwrap(), ctx.tot()) { a -= 1 },
+                recv(r1.chan.rx()) -> v => if r1.recv(v.unwrap(), ctx.tot()) { a -= 1 },
+                recv(r2.chan.rx()) -> v => if r2.recv(v.unwrap(), ctx.tot()) { a -= 1 },
+                recv(r3.chan.rx()) -> v => if r3.recv(v.unwrap(), ctx.tot()) { a -= 1 },
+                send(s0.chan.tx(), s0.sv()) -> _ => if s0.send(ctx.tot()) { a -= 1 },
+                send(s1.chan.tx(), s1.sv()) -> _ => if s1.send(ctx.tot()) { a -= 1 },
+                send(s2.chan.tx(), s2.sv()) -> _ => if s2.send(ctx.tot()) { a -= 1 },
+                send(s3.chan.tx(), s3.sv()) -> _ => if s3.send(ctx.tot()) { a -= 1 },
+            }
+            if a == 0 {
+                break;
+            }
+        }
+        change_nproc(-1, ctx.nproc());
+    }
+
+    fn get(vec: &[ChanWithVals], idx: usize) -> ChanWithVals {
+        vec.get(idx).unwrap().clone()
+    }
+
+    /// Direct send to direct recv
+    fn test1(c: ChanWithVals, ctx: &mut Context) {
+        change_nproc(2, ctx.nproc());
+        go!(c, ctx, send(c, ctx));
+        go!(c, ctx, recv(c, ctx));
+    }
+
+    /// Direct send to select recv
+    fn test2(c: usize, ctx: &mut Context) {
+        let ca = mkchan(c, 4, ctx.cval());
+
+        change_nproc(4, ctx.nproc());
+        go!(ca, ctx, send(get(&ca, 0), ctx));
+        go!(ca, ctx, send(get(&ca, 1), ctx));
+        go!(ca, ctx, send(get(&ca, 2), ctx));
+        go!(ca, ctx, send(get(&ca, 3), ctx));
+
+        change_nproc(1, ctx.nproc());
+        go!(
+            ca,
+            ctx,
+            sel(
+                get(&ca, 0),
+                get(&ca, 1),
+                get(&ca, 2),
+                get(&ca, 3),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx,
+            )
+        );
+    }
+
+    /// Select send to direct recv
+    fn test3(c: usize, ctx: &mut Context) {
+        let ca = mkchan(c, 4, ctx.cval());
+
+        change_nproc(4, ctx.nproc());
+        go!(ca, ctx, recv(get(&ca, 0), ctx));
+        go!(ca, ctx, recv(get(&ca, 1), ctx));
+        go!(ca, ctx, recv(get(&ca, 2), ctx));
+        go!(ca, ctx, recv(get(&ca, 3), ctx));
+
+        change_nproc(1, ctx.nproc());
+        go!(
+            ca,
+            ctx,
+            sel(
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                get(&ca, 0),
+                get(&ca, 1),
+                get(&ca, 2),
+                get(&ca, 3),
+                ctx,
+            )
+        );
+    }
+
+    /// Select send to select recv, 4 channels
+    fn test4(c: usize, ctx: &mut Context) {
+        let ca = mkchan(c, 4, ctx.cval());
+
+        change_nproc(2, ctx.nproc());
+        go!(
+            ca,
+            ctx,
+            sel(
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                get(&ca, 0),
+                get(&ca, 1),
+                get(&ca, 2),
+                get(&ca, 3),
+                ctx,
+            )
+        );
+        go!(
+            ca,
+            ctx,
+            sel(
+                get(&ca, 0),
+                get(&ca, 1),
+                get(&ca, 2),
+                get(&ca, 3),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx.nc.clone(),
+                ctx,
+            )
+        );
+    }
+
+    /// Select send to select recv, 8 channels
+    fn test5(c: usize, ctx: &mut Context) {
+        let ca = mkchan(c, 8, ctx.cval());
+
+        change_nproc(2, ctx.nproc());
+        go!(
+            ca,
+            ctx,
+            sel(
+                get(&ca, 4),
+                get(&ca, 5),
+                get(&ca, 6),
+                get(&ca, 7),
+                get(&ca, 0),
+                get(&ca, 1),
+                get(&ca, 2),
+                get(&ca, 3),
+                ctx,
+            )
+        );
+        go!(
+            ca,
+            ctx,
+            sel(
+                get(&ca, 0),
+                get(&ca, 1),
+                get(&ca, 2),
+                get(&ca, 3),
+                get(&ca, 4),
+                get(&ca, 5),
+                get(&ca, 6),
+                get(&ca, 7),
+                ctx,
+            )
+        );
+    }
+
+    // Direct and select send to direct and select recv
+    fn test6(c: usize, ctx: &mut Context) {
+        let ca = mkchan(c, 12, ctx.cval());
+
+        change_nproc(4, ctx.nproc());
+        go!(ca, ctx, send(get(&ca, 4), ctx));
+        go!(ca, ctx, send(get(&ca, 5), ctx));
+        go!(ca, ctx, send(get(&ca, 6), ctx));
+        go!(ca, ctx, send(get(&ca, 7), ctx));
+
+        change_nproc(4, ctx.nproc());
+        go!(ca, ctx, recv(get(&ca, 8), ctx));
+        go!(ca, ctx, recv(get(&ca, 9), ctx));
+        go!(ca, ctx, recv(get(&ca, 10), ctx));
+        go!(ca, ctx, recv(get(&ca, 11), ctx));
+
+        change_nproc(2, ctx.nproc());
+        go!(
+            ca,
+            ctx,
+            sel(
+                get(&ca, 4),
+                get(&ca, 5),
+                get(&ca, 6),
+                get(&ca, 7),
+                get(&ca, 0),
+                get(&ca, 1),
+                get(&ca, 2),
+                get(&ca, 3),
+                ctx,
+            )
+        );
+        go!(
+            ca,
+            ctx,
+            sel(
+                get(&ca, 0),
+                get(&ca, 1),
+                get(&ca, 2),
+                get(&ca, 3),
+                get(&ca, 8),
+                get(&ca, 9),
+                get(&ca, 10),
+                get(&ca, 11),
+                ctx,
+            )
+        );
+    }
+
+    fn wait(ctx: &mut Context) {
+        thread::yield_now();
+        while change_nproc(0, ctx.nproc()) != 0 {
+            thread::yield_now();
+        }
+    }
+
+    fn tests(c: usize, ctx: &mut Context) {
+        let ca = mkchan(c, 4, ctx.cval());
+        test1(get(&ca, 0), ctx);
+        test1(get(&ca, 1), ctx);
+        test1(get(&ca, 2), ctx);
+        test1(get(&ca, 3), ctx);
+        wait(ctx);
+
+        test2(c, ctx);
+        wait(ctx);
+
+        test3(c, ctx);
+        wait(ctx);
+
+        test4(c, ctx);
+        wait(ctx);
+
+        test5(c, ctx);
+        wait(ctx);
+
+        test6(c, ctx);
+        wait(ctx);
+    }
+
+    #[test]
+    fn main() {
+        let mut ctx = Context {
+            nproc: Arc::new(Mutex::new(0)),
+            cval: Arc::new(Mutex::new(0)),
+            tot: Arc::new(Mutex::new(Totals { tots: 0, totr: 0 })),
+            nc: ChanWithVals::closed(),
+            randx: Arc::new(Mutex::new(0)),
+        };
+
+        tests(0, &mut ctx);
+        tests(1, &mut ctx);
+        tests(10, &mut ctx);
+        tests(100, &mut ctx);
+
+        #[rustfmt::skip]
+        let t = 4 * // buffer sizes
+                    (4*4 + // tests 1,2,3,4 channels
+                            8 + // test 5 channels
+                            12) * // test 6 channels
+                        MESSAGES_PER_CHANEL; // sends/recvs on a channel
+
+        let tot = ctx.tot.lock().unwrap();
+        if tot.tots != t || tot.totr != t {
+            panic!("tots={} totr={} sb={}", tot.tots, tot.totr, t);
+        }
+    }
 }
 
 // https://github.com/golang/go/blob/master/test/ken/chan1.go
@@ -1551,7 +2086,7 @@
 
     // sent messages
     #[cfg(miri)]
-    const N: usize = 100;
+    const N: usize = 20;
     #[cfg(not(miri))]
     const N: usize = 1000;
     // receiving "goroutines"
diff --git a/tests/list.rs b/tests/list.rs
index 619e1fc..a0b9087 100644
--- a/tests/list.rs
+++ b/tests/list.rs
@@ -132,8 +132,13 @@
 
 #[test]
 fn try_send() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 1000;
+
     let (s, r) = unbounded();
-    for i in 0..1000 {
+    for i in 0..COUNT {
         assert_eq!(s.try_send(i), Ok(()));
     }
 
@@ -143,8 +148,13 @@
 
 #[test]
 fn send() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 1000;
+
     let (s, r) = unbounded();
-    for i in 0..1000 {
+    for i in 0..COUNT {
         assert_eq!(s.send(i), Ok(()));
     }
 
@@ -154,8 +164,13 @@
 
 #[test]
 fn send_timeout() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 1000;
+
     let (s, r) = unbounded();
-    for i in 0..1000 {
+    for i in 0..COUNT {
         assert_eq!(s.send_timeout(i, ms(i as u64)), Ok(()));
     }
 
@@ -383,10 +398,16 @@
     .unwrap();
 }
 
-#[cfg_attr(miri, ignore)] // Miri is too slow
 #[test]
 fn drops() {
+    #[cfg(miri)]
+    const RUNS: usize = 20;
+    #[cfg(not(miri))]
     const RUNS: usize = 100;
+    #[cfg(miri)]
+    const STEPS: usize = 100;
+    #[cfg(not(miri))]
+    const STEPS: usize = 10_000;
 
     static DROPS: AtomicUsize = AtomicUsize::new(0);
 
@@ -402,8 +423,8 @@
     let mut rng = thread_rng();
 
     for _ in 0..RUNS {
-        let steps = rng.gen_range(0..10_000);
-        let additional = rng.gen_range(0..1000);
+        let steps = rng.gen_range(0..STEPS);
+        let additional = rng.gen_range(0..STEPS / 10);
 
         DROPS.store(0, Ordering::SeqCst);
         let (s, r) = unbounded::<DropCounter>();
@@ -412,6 +433,8 @@
             scope.spawn(|_| {
                 for _ in 0..steps {
                     r.recv().unwrap();
+                    #[cfg(miri)]
+                    std::thread::yield_now(); // https://github.com/rust-lang/miri/issues/1388
                 }
             });
 
diff --git a/tests/mpsc.rs b/tests/mpsc.rs
index 4d6e179..3db4812 100644
--- a/tests/mpsc.rs
+++ b/tests/mpsc.rs
@@ -321,7 +321,7 @@
     #[test]
     fn stress() {
         #[cfg(miri)]
-        const COUNT: usize = 500;
+        const COUNT: usize = 100;
         #[cfg(not(miri))]
         const COUNT: usize = 10000;
 
@@ -340,7 +340,7 @@
     #[test]
     fn stress_shared() {
         #[cfg(miri)]
-        const AMT: u32 = 500;
+        const AMT: u32 = 100;
         #[cfg(not(miri))]
         const AMT: u32 = 10000;
         const NTHREADS: u32 = 8;
@@ -747,7 +747,7 @@
     #[test]
     fn recv_a_lot() {
         #[cfg(miri)]
-        const N: usize = 100;
+        const N: usize = 50;
         #[cfg(not(miri))]
         const N: usize = 10000;
 
diff --git a/tests/select.rs b/tests/select.rs
index f24aed8..e7691f5 100644
--- a/tests/select.rs
+++ b/tests/select.rs
@@ -694,7 +694,7 @@
 #[test]
 fn stress_recv() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
@@ -735,7 +735,7 @@
 #[test]
 fn stress_send() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
@@ -953,7 +953,7 @@
 #[test]
 fn channel_through_channel() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 1000;
 
@@ -1014,7 +1014,7 @@
 #[test]
 fn linearizable_try() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 100_000;
 
@@ -1069,7 +1069,7 @@
 #[test]
 fn linearizable_timeout() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 100_000;
 
@@ -1124,7 +1124,7 @@
 #[test]
 fn fairness1() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
@@ -1173,7 +1173,7 @@
 #[test]
 fn fairness2() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
@@ -1292,7 +1292,7 @@
 #[test]
 fn reuse() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
diff --git a/tests/select_macro.rs b/tests/select_macro.rs
index 0b9a21a..91c04e1 100644
--- a/tests/select_macro.rs
+++ b/tests/select_macro.rs
@@ -488,7 +488,7 @@
 #[test]
 fn stress_recv() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
@@ -1468,3 +1468,14 @@
     })
     .unwrap();
 }
+
+#[test]
+fn trailing_comma() {
+    let (s, r) = unbounded::<usize>();
+
+    select! {
+        send(s, 1,) -> _ => {},
+        recv(r,) -> _ => {},
+        default(ms(1000),) => {},
+    }
+}
diff --git a/tests/zero.rs b/tests/zero.rs
index ba41b1a..c90d741 100644
--- a/tests/zero.rs
+++ b/tests/zero.rs
@@ -188,7 +188,7 @@
 #[test]
 fn len() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 25_000;
 
@@ -253,7 +253,7 @@
 #[test]
 fn spsc() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 100_000;
 
@@ -278,7 +278,7 @@
 #[test]
 fn mpmc() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 25_000;
     const THREADS: usize = 4;
@@ -313,7 +313,7 @@
 #[test]
 fn stress_oneshot() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
@@ -396,10 +396,16 @@
     .unwrap();
 }
 
-#[cfg_attr(miri, ignore)] // Miri is too slow
 #[test]
 fn drops() {
+    #[cfg(miri)]
+    const RUNS: usize = 20;
+    #[cfg(not(miri))]
     const RUNS: usize = 100;
+    #[cfg(miri)]
+    const STEPS: usize = 500;
+    #[cfg(not(miri))]
+    const STEPS: usize = 10_000;
 
     static DROPS: AtomicUsize = AtomicUsize::new(0);
 
@@ -415,7 +421,7 @@
     let mut rng = thread_rng();
 
     for _ in 0..RUNS {
-        let steps = rng.gen_range(0..3_000);
+        let steps = rng.gen_range(0..STEPS);
 
         DROPS.store(0, Ordering::SeqCst);
         let (s, r) = bounded::<DropCounter>(0);
@@ -445,7 +451,7 @@
 #[test]
 fn fairness() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
@@ -479,7 +485,7 @@
 #[test]
 fn fairness_duplicates() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 10_000;
 
@@ -540,7 +546,7 @@
 #[test]
 fn channel_through_channel() {
     #[cfg(miri)]
-    const COUNT: usize = 100;
+    const COUNT: usize = 50;
     #[cfg(not(miri))]
     const COUNT: usize = 1000;