Auto merge of #73265 - mark-i-m:mv-std, r=<try>tmp-nightly

mv std libs to library/

This is the first step in refactoring the directory layout of this repository, with further followup steps planned (but not done yet).

Background: currently, all crates are under src/, without nested src directories and with the unconventional `lib*` prefixes (e.g., `src/libcore/lib.rs`). This directory structures is not idiomatic and makes the `src/` directory rather overwhelming. To improve contributor experience and make things a bit more approachable, we are reorganizing the repo a bit.

In this PR, we move the standard libs (basically anything that is "runtime", as opposed to part of the compiler, build system, or one of the tools, etc). The new layout moves these libraries to a new `library/` directory in the root of the repo. Additionally, we remove the `lib*` prefixes and add nested `src/` directories.  The other crates/tools in this repo are not touched. So in summary:

```
library/<crate>/src/*.rs
src/<all the rest>     // unchanged
```

where `<crate>` is:
- core
- alloc
- std
- test
- proc_macro
- panic_abort
- panic_unwind
- profiler_builtins
- term
- unwind
- rtstartup
- backtrace
- rustc-std-workspace-*

There was a lot of discussion about this and a few rounds of compiler team approvals, FCPs, MCPs, and nominations. The original MCP is https://github.com/rust-lang/compiler-team/issues/298. The final approval of the compiler team was given here: https://github.com/rust-lang/rust/pull/73265#issuecomment-659498446.

The name `library` was chosen to complement a later move of the compiler crates to a `compiler/` directory. There was a lot of discussion around adding the nested `src/` directories. Note that this does increase the nesting depth (plausibly important for manual traversal of the tree, e.g., through GitHub's UI or `cd`), but this is deemed to be better as it fits the standard layout of Rust crates throughout most of the ecosystem, though there is some debate about how much this should apply to multi-crate projects. Overall, there seem to be more people in favor of nested `src/` than against.

After this PR, there are no dependencies out of the `library/` directory except on the `build_helper` (or crates.io crates).

1 files changed, 0 insertions, 799 deletions

diff --git a/src/libstd/sync/rwlock.rs b/src/libstd/sync/rwlock.rs
deleted file mode 100644
index 50f54dbf143..00000000000
--- a/src/libstd/sync/rwlock.rs
+++ /dev/null
@@ -1,799 +0,0 @@
-use crate::cell::UnsafeCell;
-use crate::fmt;
-use crate::mem;
-use crate::ops::{Deref, DerefMut};
-use crate::ptr;
-use crate::sys_common::poison::{self, LockResult, TryLockError, TryLockResult};
-use crate::sys_common::rwlock as sys;
-
-/// A reader-writer lock
-///
-/// This type of lock allows a number of readers or at most one writer at any
-/// point in time. The write portion of this lock typically allows modification
-/// of the underlying data (exclusive access) and the read portion of this lock
-/// typically allows for read-only access (shared access).
-///
-/// In comparison, a [`Mutex`] does not distinguish between readers or writers
-/// that acquire the lock, therefore blocking any threads waiting for the lock to
-/// become available. An `RwLock` will allow any number of readers to acquire the
-/// lock as long as a writer is not holding the lock.
-///
-/// The priority policy of the lock is dependent on the underlying operating
-/// system's implementation, and this type does not guarantee that any
-/// particular policy will be used.
-///
-/// The type parameter `T` represents the data that this lock protects. It is
-/// required that `T` satisfies [`Send`] to be shared across threads and
-/// [`Sync`] to allow concurrent access through readers. The RAII guards
-/// returned from the locking methods implement [`Deref`] (and [`DerefMut`]
-/// for the `write` methods) to allow access to the content of the lock.
-///
-/// # Poisoning
-///
-/// An `RwLock`, like [`Mutex`], will become poisoned on a panic. Note, however,
-/// that an `RwLock` may only be poisoned if a panic occurs while it is locked
-/// exclusively (write mode). If a panic occurs in any reader, then the lock
-/// will not be poisoned.
-///
-/// # Examples
-///
-/// ```
-/// use std::sync::RwLock;
-///
-/// let lock = RwLock::new(5);
-///
-/// // many reader locks can be held at once
-/// {
-///     let r1 = lock.read().unwrap();
-///     let r2 = lock.read().unwrap();
-///     assert_eq!(*r1, 5);
-///     assert_eq!(*r2, 5);
-/// } // read locks are dropped at this point
-///
-/// // only one write lock may be held, however
-/// {
-///     let mut w = lock.write().unwrap();
-///     *w += 1;
-///     assert_eq!(*w, 6);
-/// } // write lock is dropped here
-/// ```
-///
-/// [`Deref`]: ../../std/ops/trait.Deref.html
-/// [`DerefMut`]: ../../std/ops/trait.DerefMut.html
-/// [`Send`]: ../../std/marker/trait.Send.html
-/// [`Sync`]: ../../std/marker/trait.Sync.html
-/// [`Mutex`]: struct.Mutex.html
-#[stable(feature = "rust1", since = "1.0.0")]
-pub struct RwLock<T: ?Sized> {
-    inner: Box<sys::RWLock>,
-    poison: poison::Flag,
-    data: UnsafeCell<T>,
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<T: ?Sized + Send> Send for RwLock<T> {}
-#[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}
-
-/// RAII structure used to release the shared read access of a lock when
-/// dropped.
-///
-/// This structure is created by the [`read`] and [`try_read`] methods on
-/// [`RwLock`].
-///
-/// [`read`]: struct.RwLock.html#method.read
-/// [`try_read`]: struct.RwLock.html#method.try_read
-/// [`RwLock`]: struct.RwLock.html
-#[must_use = "if unused the RwLock will immediately unlock"]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
-    lock: &'a RwLock<T>,
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> !Send for RwLockReadGuard<'_, T> {}
-
-#[stable(feature = "rwlock_guard_sync", since = "1.23.0")]
-unsafe impl<T: ?Sized + Sync> Sync for RwLockReadGuard<'_, T> {}
-
-/// RAII structure used to release the exclusive write access of a lock when
-/// dropped.
-///
-/// This structure is created by the [`write`] and [`try_write`] methods
-/// on [`RwLock`].
-///
-/// [`write`]: struct.RwLock.html#method.write
-/// [`try_write`]: struct.RwLock.html#method.try_write
-/// [`RwLock`]: struct.RwLock.html
-#[must_use = "if unused the RwLock will immediately unlock"]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> {
-    lock: &'a RwLock<T>,
-    poison: poison::Guard,
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> !Send for RwLockWriteGuard<'_, T> {}
-
-#[stable(feature = "rwlock_guard_sync", since = "1.23.0")]
-unsafe impl<T: ?Sized + Sync> Sync for RwLockWriteGuard<'_, T> {}
-
-impl<T> RwLock<T> {
-    /// Creates a new instance of an `RwLock<T>` which is unlocked.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::sync::RwLock;
-    ///
-    /// let lock = RwLock::new(5);
-    /// ```
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn new(t: T) -> RwLock<T> {
-        RwLock {
-            inner: box sys::RWLock::new(),
-            poison: poison::Flag::new(),
-            data: UnsafeCell::new(t),
-        }
-    }
-}
-
-impl<T: ?Sized> RwLock<T> {
-    /// Locks this rwlock with shared read access, blocking the current thread
-    /// until it can be acquired.
-    ///
-    /// The calling thread will be blocked until there are no more writers which
-    /// hold the lock. There may be other readers currently inside the lock when
-    /// this method returns. This method does not provide any guarantees with
-    /// respect to the ordering of whether contentious readers or writers will
-    /// acquire the lock first.
-    ///
-    /// Returns an RAII guard which will release this thread's shared access
-    /// once it is dropped.
-    ///
-    /// # Errors
-    ///
-    /// This function will return an error if the RwLock is poisoned. An RwLock
-    /// is poisoned whenever a writer panics while holding an exclusive lock.
-    /// The failure will occur immediately after the lock has been acquired.
-    ///
-    /// # Panics
-    ///
-    /// This function might panic when called if the lock is already held by the current thread.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::sync::{Arc, RwLock};
-    /// use std::thread;
-    ///
-    /// let lock = Arc::new(RwLock::new(1));
-    /// let c_lock = lock.clone();
-    ///
-    /// let n = lock.read().unwrap();
-    /// assert_eq!(*n, 1);
-    ///
-    /// thread::spawn(move || {
-    ///     let r = c_lock.read();
-    ///     assert!(r.is_ok());
-    /// }).join().unwrap();
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn read(&self) -> LockResult<RwLockReadGuard<'_, T>> {
-        unsafe {
-            self.inner.read();
-            RwLockReadGuard::new(self)
-        }
-    }
-
-    /// Attempts to acquire this rwlock with shared read access.
-    ///
-    /// If the access could not be granted at this time, then `Err` is returned.
-    /// Otherwise, an RAII guard is returned which will release the shared access
-    /// when it is dropped.
-    ///
-    /// This function does not block.
-    ///
-    /// This function does not provide any guarantees with respect to the ordering
-    /// of whether contentious readers or writers will acquire the lock first.
-    ///
-    /// # Errors
-    ///
-    /// This function will return an error if the RwLock is poisoned. An RwLock
-    /// is poisoned whenever a writer panics while holding an exclusive lock. An
-    /// error will only be returned if the lock would have otherwise been
-    /// acquired.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::sync::RwLock;
-    ///
-    /// let lock = RwLock::new(1);
-    ///
-    /// match lock.try_read() {
-    ///     Ok(n) => assert_eq!(*n, 1),
-    ///     Err(_) => unreachable!(),
-    /// };
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn try_read(&self) -> TryLockResult<RwLockReadGuard<'_, T>> {
-        unsafe {
-            if self.inner.try_read() {
-                Ok(RwLockReadGuard::new(self)?)
-            } else {
-                Err(TryLockError::WouldBlock)
-            }
-        }
-    }
-
-    /// Locks this rwlock with exclusive write access, blocking the current
-    /// thread until it can be acquired.
-    ///
-    /// This function will not return while other writers or other readers
-    /// currently have access to the lock.
-    ///
-    /// Returns an RAII guard which will drop the write access of this rwlock
-    /// when dropped.
-    ///
-    /// # Errors
-    ///
-    /// This function will return an error if the RwLock is poisoned. An RwLock
-    /// is poisoned whenever a writer panics while holding an exclusive lock.
-    /// An error will be returned when the lock is acquired.
-    ///
-    /// # Panics
-    ///
-    /// This function might panic when called if the lock is already held by the current thread.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::sync::RwLock;
-    ///
-    /// let lock = RwLock::new(1);
-    ///
-    /// let mut n = lock.write().unwrap();
-    /// *n = 2;
-    ///
-    /// assert!(lock.try_read().is_err());
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn write(&self) -> LockResult<RwLockWriteGuard<'_, T>> {
-        unsafe {
-            self.inner.write();
-            RwLockWriteGuard::new(self)
-        }
-    }
-
-    /// Attempts to lock this rwlock with exclusive write access.
-    ///
-    /// If the lock could not be acquired at this time, then `Err` is returned.
-    /// Otherwise, an RAII guard is returned which will release the lock when
-    /// it is dropped.
-    ///
-    /// This function does not block.
-    ///
-    /// This function does not provide any guarantees with respect to the ordering
-    /// of whether contentious readers or writers will acquire the lock first.
-    ///
-    /// # Errors
-    ///
-    /// This function will return an error if the RwLock is poisoned. An RwLock
-    /// is poisoned whenever a writer panics while holding an exclusive lock. An
-    /// error will only be returned if the lock would have otherwise been
-    /// acquired.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::sync::RwLock;
-    ///
-    /// let lock = RwLock::new(1);
-    ///
-    /// let n = lock.read().unwrap();
-    /// assert_eq!(*n, 1);
-    ///
-    /// assert!(lock.try_write().is_err());
-    /// ```
-    #[inline]
-    #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn try_write(&self) -> TryLockResult<RwLockWriteGuard<'_, T>> {
-        unsafe {
-            if self.inner.try_write() {
-                Ok(RwLockWriteGuard::new(self)?)
-            } else {
-                Err(TryLockError::WouldBlock)
-            }
-        }
-    }
-
-    /// Determines whether the lock is poisoned.
-    ///
-    /// If another thread is active, the lock can still become poisoned at any
-    /// time. You should not trust a `false` value for program correctness
-    /// without additional synchronization.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::sync::{Arc, RwLock};
-    /// use std::thread;
-    ///
-    /// let lock = Arc::new(RwLock::new(0));
-    /// let c_lock = lock.clone();
-    ///
-    /// let _ = thread::spawn(move || {
-    ///     let _lock = c_lock.write().unwrap();
-    ///     panic!(); // the lock gets poisoned
-    /// }).join();
-    /// assert_eq!(lock.is_poisoned(), true);
-    /// ```
-    #[inline]
-    #[stable(feature = "sync_poison", since = "1.2.0")]
-    pub fn is_poisoned(&self) -> bool {
-        self.poison.get()
-    }
-
-    /// Consumes this `RwLock`, returning the underlying data.
-    ///
-    /// # Errors
-    ///
-    /// This function will return an error if the RwLock is poisoned. An RwLock
-    /// is poisoned whenever a writer panics while holding an exclusive lock. An
-    /// error will only be returned if the lock would have otherwise been
-    /// acquired.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::sync::RwLock;
-    ///
-    /// let lock = RwLock::new(String::new());
-    /// {
-    ///     let mut s = lock.write().unwrap();
-    ///     *s = "modified".to_owned();
-    /// }
-    /// assert_eq!(lock.into_inner().unwrap(), "modified");
-    /// ```
-    #[stable(feature = "rwlock_into_inner", since = "1.6.0")]
-    pub fn into_inner(self) -> LockResult<T>
-    where
-        T: Sized,
-    {
-        // We know statically that there are no outstanding references to
-        // `self` so there's no need to lock the inner lock.
-        //
-        // To get the inner value, we'd like to call `data.into_inner()`,
-        // but because `RwLock` impl-s `Drop`, we can't move out of it, so
-        // we'll have to destructure it manually instead.
-        unsafe {
-            // Like `let RwLock { inner, poison, data } = self`.
-            let (inner, poison, data) = {
-                let RwLock { ref inner, ref poison, ref data } = self;
-                (ptr::read(inner), ptr::read(poison), ptr::read(data))
-            };
-            mem::forget(self);
-            inner.destroy(); // Keep in sync with the `Drop` impl.
-            drop(inner);
-
-            poison::map_result(poison.borrow(), |_| data.into_inner())
-        }
-    }
-
-    /// Returns a mutable reference to the underlying data.
-    ///
-    /// Since this call borrows the `RwLock` mutably, no actual locking needs to
-    /// take place -- the mutable borrow statically guarantees no locks exist.
-    ///
-    /// # Errors
-    ///
-    /// This function will return an error if the RwLock is poisoned. An RwLock
-    /// is poisoned whenever a writer panics while holding an exclusive lock. An
-    /// error will only be returned if the lock would have otherwise been
-    /// acquired.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use std::sync::RwLock;
-    ///
-    /// let mut lock = RwLock::new(0);
-    /// *lock.get_mut().unwrap() = 10;
-    /// assert_eq!(*lock.read().unwrap(), 10);
-    /// ```
-    #[stable(feature = "rwlock_get_mut", since = "1.6.0")]
-    pub fn get_mut(&mut self) -> LockResult<&mut T> {
-        // We know statically that there are no other references to `self`, so
-        // there's no need to lock the inner lock.
-        let data = unsafe { &mut *self.data.get() };
-        poison::map_result(self.poison.borrow(), |_| data)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-unsafe impl<#[may_dangle] T: ?Sized> Drop for RwLock<T> {
-    fn drop(&mut self) {
-        // IMPORTANT: This code needs to be kept in sync with `RwLock::into_inner`.
-        unsafe { self.inner.destroy() }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized + fmt::Debug> fmt::Debug for RwLock<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self.try_read() {
-            Ok(guard) => f.debug_struct("RwLock").field("data", &&*guard).finish(),
-            Err(TryLockError::Poisoned(err)) => {
-                f.debug_struct("RwLock").field("data", &&**err.get_ref()).finish()
-            }
-            Err(TryLockError::WouldBlock) => {
-                struct LockedPlaceholder;
-                impl fmt::Debug for LockedPlaceholder {
-                    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                        f.write_str("<locked>")
-                    }
-                }
-
-                f.debug_struct("RwLock").field("data", &LockedPlaceholder).finish()
-            }
-        }
-    }
-}
-
-#[stable(feature = "rw_lock_default", since = "1.10.0")]
-impl<T: Default> Default for RwLock<T> {
-    /// Creates a new `RwLock<T>`, with the `Default` value for T.
-    fn default() -> RwLock<T> {
-        RwLock::new(Default::default())
-    }
-}
-
-#[stable(feature = "rw_lock_from", since = "1.24.0")]
-impl<T> From<T> for RwLock<T> {
-    /// Creates a new instance of an `RwLock<T>` which is unlocked.
-    /// This is equivalent to [`RwLock::new`].
-    ///
-    /// [`RwLock::new`]: ../../std/sync/struct.RwLock.html#method.new
-    fn from(t: T) -> Self {
-        RwLock::new(t)
-    }
-}
-
-impl<'rwlock, T: ?Sized> RwLockReadGuard<'rwlock, T> {
-    unsafe fn new(lock: &'rwlock RwLock<T>) -> LockResult<RwLockReadGuard<'rwlock, T>> {
-        poison::map_result(lock.poison.borrow(), |_| RwLockReadGuard { lock })
-    }
-}
-
-impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
-    unsafe fn new(lock: &'rwlock RwLock<T>) -> LockResult<RwLockWriteGuard<'rwlock, T>> {
-        poison::map_result(lock.poison.borrow(), |guard| RwLockWriteGuard { lock, poison: guard })
-    }
-}
-
-#[stable(feature = "std_debug", since = "1.16.0")]
-impl<T: fmt::Debug> fmt::Debug for RwLockReadGuard<'_, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("RwLockReadGuard").field("lock", &self.lock).finish()
-    }
-}
-
-#[stable(feature = "std_guard_impls", since = "1.20.0")]
-impl<T: ?Sized + fmt::Display> fmt::Display for RwLockReadGuard<'_, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        (**self).fmt(f)
-    }
-}
-
-#[stable(feature = "std_debug", since = "1.16.0")]
-impl<T: fmt::Debug> fmt::Debug for RwLockWriteGuard<'_, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("RwLockWriteGuard").field("lock", &self.lock).finish()
-    }
-}
-
-#[stable(feature = "std_guard_impls", since = "1.20.0")]
-impl<T: ?Sized + fmt::Display> fmt::Display for RwLockWriteGuard<'_, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        (**self).fmt(f)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> Deref for RwLockReadGuard<'_, T> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        unsafe { &*self.lock.data.get() }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> Deref for RwLockWriteGuard<'_, T> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        unsafe { &*self.lock.data.get() }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> DerefMut for RwLockWriteGuard<'_, T> {
-    fn deref_mut(&mut self) -> &mut T {
-        unsafe { &mut *self.lock.data.get() }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> Drop for RwLockReadGuard<'_, T> {
-    fn drop(&mut self) {
-        unsafe {
-            self.lock.inner.read_unlock();
-        }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: ?Sized> Drop for RwLockWriteGuard<'_, T> {
-    fn drop(&mut self) {
-        self.lock.poison.done(&self.poison);
-        unsafe {
-            self.lock.inner.write_unlock();
-        }
-    }
-}
-
-#[cfg(all(test, not(target_os = "emscripten")))]
-mod tests {
-    use crate::sync::atomic::{AtomicUsize, Ordering};
-    use crate::sync::mpsc::channel;
-    use crate::sync::{Arc, RwLock, TryLockError};
-    use crate::thread;
-    use rand::{self, Rng};
-
-    #[derive(Eq, PartialEq, Debug)]
-    struct NonCopy(i32);
-
-    #[test]
-    fn smoke() {
-        let l = RwLock::new(());
-        drop(l.read().unwrap());
-        drop(l.write().unwrap());
-        drop((l.read().unwrap(), l.read().unwrap()));
-        drop(l.write().unwrap());
-    }
-
-    #[test]
-    fn frob() {
-        const N: u32 = 10;
-        const M: usize = 1000;
-
-        let r = Arc::new(RwLock::new(()));
-
-        let (tx, rx) = channel::<()>();
-        for _ in 0..N {
-            let tx = tx.clone();
-            let r = r.clone();
-            thread::spawn(move || {
-                let mut rng = rand::thread_rng();
-                for _ in 0..M {
-                    if rng.gen_bool(1.0 / (N as f64)) {
-                        drop(r.write().unwrap());
-                    } else {
-                        drop(r.read().unwrap());
-                    }
-                }
-                drop(tx);
-            });
-        }
-        drop(tx);
-        let _ = rx.recv();
-    }
-
-    #[test]
-    fn test_rw_arc_poison_wr() {
-        let arc = Arc::new(RwLock::new(1));
-        let arc2 = arc.clone();
-        let _: Result<(), _> = thread::spawn(move || {
-            let _lock = arc2.write().unwrap();
-            panic!();
-        })
-        .join();
-        assert!(arc.read().is_err());
-    }
-
-    #[test]
-    fn test_rw_arc_poison_ww() {
-        let arc = Arc::new(RwLock::new(1));
-        assert!(!arc.is_poisoned());
-        let arc2 = arc.clone();
-        let _: Result<(), _> = thread::spawn(move || {
-            let _lock = arc2.write().unwrap();
-            panic!();
-        })
-        .join();
-        assert!(arc.write().is_err());
-        assert!(arc.is_poisoned());
-    }
-
-    #[test]
-    fn test_rw_arc_no_poison_rr() {
-        let arc = Arc::new(RwLock::new(1));
-        let arc2 = arc.clone();
-        let _: Result<(), _> = thread::spawn(move || {
-            let _lock = arc2.read().unwrap();
-            panic!();
-        })
-        .join();
-        let lock = arc.read().unwrap();
-        assert_eq!(*lock, 1);
-    }
-    #[test]
-    fn test_rw_arc_no_poison_rw() {
-        let arc = Arc::new(RwLock::new(1));
-        let arc2 = arc.clone();
-        let _: Result<(), _> = thread::spawn(move || {
-            let _lock = arc2.read().unwrap();
-            panic!()
-        })
-        .join();
-        let lock = arc.write().unwrap();
-        assert_eq!(*lock, 1);
-    }
-
-    #[test]
-    fn test_rw_arc() {
-        let arc = Arc::new(RwLock::new(0));
-        let arc2 = arc.clone();
-        let (tx, rx) = channel();
-
-        thread::spawn(move || {
-            let mut lock = arc2.write().unwrap();
-            for _ in 0..10 {
-                let tmp = *lock;
-                *lock = -1;
-                thread::yield_now();
-                *lock = tmp + 1;
-            }
-            tx.send(()).unwrap();
-        });
-
-        // Readers try to catch the writer in the act
-        let mut children = Vec::new();
-        for _ in 0..5 {
-            let arc3 = arc.clone();
-            children.push(thread::spawn(move || {
-                let lock = arc3.read().unwrap();
-                assert!(*lock >= 0);
-            }));
-        }
-
-        // Wait for children to pass their asserts
-        for r in children {
-            assert!(r.join().is_ok());
-        }
-
-        // Wait for writer to finish
-        rx.recv().unwrap();
-        let lock = arc.read().unwrap();
-        assert_eq!(*lock, 10);
-    }
-
-    #[test]
-    fn test_rw_arc_access_in_unwind() {
-        let arc = Arc::new(RwLock::new(1));
-        let arc2 = arc.clone();
-        let _ = thread::spawn(move || -> () {
-            struct Unwinder {
-                i: Arc<RwLock<isize>>,
-            }
-            impl Drop for Unwinder {
-                fn drop(&mut self) {
-                    let mut lock = self.i.write().unwrap();
-                    *lock += 1;
-                }
-            }
-            let _u = Unwinder { i: arc2 };
-            panic!();
-        })
-        .join();
-        let lock = arc.read().unwrap();
-        assert_eq!(*lock, 2);
-    }
-
-    #[test]
-    fn test_rwlock_unsized() {
-        let rw: &RwLock<[i32]> = &RwLock::new([1, 2, 3]);
-        {
-            let b = &mut *rw.write().unwrap();
-            b[0] = 4;
-            b[2] = 5;
-        }
-        let comp: &[i32] = &[4, 2, 5];
-        assert_eq!(&*rw.read().unwrap(), comp);
-    }
-
-    #[test]
-    fn test_rwlock_try_write() {
-        let lock = RwLock::new(0isize);
-        let read_guard = lock.read().unwrap();
-
-        let write_result = lock.try_write();
-        match write_result {
-            Err(TryLockError::WouldBlock) => (),
-            Ok(_) => assert!(false, "try_write should not succeed while read_guard is in scope"),
-            Err(_) => assert!(false, "unexpected error"),
-        }
-
-        drop(read_guard);
-    }
-
-    #[test]
-    fn test_into_inner() {
-        let m = RwLock::new(NonCopy(10));
-        assert_eq!(m.into_inner().unwrap(), NonCopy(10));
-    }
-
-    #[test]
-    fn test_into_inner_drop() {
-        struct Foo(Arc<AtomicUsize>);
-        impl Drop for Foo {
-            fn drop(&mut self) {
-                self.0.fetch_add(1, Ordering::SeqCst);
-            }
-        }
-        let num_drops = Arc::new(AtomicUsize::new(0));
-        let m = RwLock::new(Foo(num_drops.clone()));
-        assert_eq!(num_drops.load(Ordering::SeqCst), 0);
-        {
-            let _inner = m.into_inner().unwrap();
-            assert_eq!(num_drops.load(Ordering::SeqCst), 0);
-        }
-        assert_eq!(num_drops.load(Ordering::SeqCst), 1);
-    }
-
-    #[test]
-    fn test_into_inner_poison() {
-        let m = Arc::new(RwLock::new(NonCopy(10)));
-        let m2 = m.clone();
-        let _ = thread::spawn(move || {
-            let _lock = m2.write().unwrap();
-            panic!("test panic in inner thread to poison RwLock");
-        })
-        .join();
-
-        assert!(m.is_poisoned());
-        match Arc::try_unwrap(m).unwrap().into_inner() {
-            Err(e) => assert_eq!(e.into_inner(), NonCopy(10)),
-            Ok(x) => panic!("into_inner of poisoned RwLock is Ok: {:?}", x),
-        }
-    }
-
-    #[test]
-    fn test_get_mut() {
-        let mut m = RwLock::new(NonCopy(10));
-        *m.get_mut().unwrap() = NonCopy(20);
-        assert_eq!(m.into_inner().unwrap(), NonCopy(20));
-    }
-
-    #[test]
-    fn test_get_mut_poison() {
-        let m = Arc::new(RwLock::new(NonCopy(10)));
-        let m2 = m.clone();
-        let _ = thread::spawn(move || {
-            let _lock = m2.write().unwrap();
-            panic!("test panic in inner thread to poison RwLock");
-        })
-        .join();
-
-        assert!(m.is_poisoned());
-        match Arc::try_unwrap(m).unwrap().get_mut() {
-            Err(e) => assert_eq!(*e.into_inner(), NonCopy(10)),
-            Ok(x) => panic!("get_mut of poisoned RwLock is Ok: {:?}", x),
-        }
-    }
-}