Merge from rustc

18 files changed, 367 insertions, 2279 deletions

diff --git a/compiler/rustc_data_structures/src/graph/implementation/mod.rs b/compiler/rustc_data_structures/src/graph/implementation/mod.rs
index 1aa7ac024d9..9ff401c3c7a 100644
--- a/compiler/rustc_data_structures/src/graph/implementation/mod.rs
+++ b/compiler/rustc_data_structures/src/graph/implementation/mod.rs
@@ -206,17 +206,11 @@ impl<N: Debug, E: Debug> Graph<N, E> {
         AdjacentEdges { graph: self, direction, next: first_edge }
     }
 
-    pub fn successor_nodes<'a>(
-        &'a self,
-        source: NodeIndex,
-    ) -> impl Iterator<Item = NodeIndex> + 'a {
+    pub fn successor_nodes(&self, source: NodeIndex) -> impl Iterator<Item = NodeIndex> + '_ {
         self.outgoing_edges(source).targets()
     }
 
-    pub fn predecessor_nodes<'a>(
-        &'a self,
-        target: NodeIndex,
-    ) -> impl Iterator<Item = NodeIndex> + 'a {
+    pub fn predecessor_nodes(&self, target: NodeIndex) -> impl Iterator<Item = NodeIndex> + '_ {
         self.incoming_edges(target).sources()
     }
 
diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
index 9b52638e612..e373bd18402 100644
--- a/compiler/rustc_data_structures/src/lib.rs
+++ b/compiler/rustc_data_structures/src/lib.rs
@@ -1,5 +1,5 @@
 //! Various data structures used by the Rust compiler. The intention
-//! is that code in here should be not be *specific* to rustc, so that
+//! is that code in here should not be *specific* to rustc, so that
 //! it can be easily unit tested and so forth.
 //!
 //! # Note
@@ -27,6 +27,8 @@
 #![feature(thread_id_value)]
 #![feature(vec_into_raw_parts)]
 #![feature(get_mut_unchecked)]
+#![feature(lint_reasons)]
+#![feature(unwrap_infallible)]
 #![allow(rustc::default_hash_types)]
 #![allow(rustc::potential_query_instability)]
 #![deny(rustc::untranslatable_diagnostic)]
@@ -59,7 +61,6 @@ pub mod intern;
 pub mod jobserver;
 pub mod macros;
 pub mod obligation_forest;
-pub mod owning_ref;
 pub mod sip128;
 pub mod small_c_str;
 pub mod small_str;
@@ -82,6 +83,7 @@ pub mod vec_linked_list;
 pub mod work_queue;
 pub use atomic_ref::AtomicRef;
 pub mod frozen;
+pub mod owned_slice;
 pub mod sso;
 pub mod steal;
 pub mod tagged_ptr;
diff --git a/compiler/rustc_data_structures/src/memmap.rs b/compiler/rustc_data_structures/src/memmap.rs
index 3d44e17f31d..ef37a606f31 100644
--- a/compiler/rustc_data_structures/src/memmap.rs
+++ b/compiler/rustc_data_structures/src/memmap.rs
@@ -2,9 +2,7 @@ use std::fs::File;
 use std::io;
 use std::ops::{Deref, DerefMut};
 
-use crate::owning_ref::StableAddress;
-
-/// A trivial wrapper for [`memmap2::Mmap`] that implements [`StableAddress`].
+/// A trivial wrapper for [`memmap2::Mmap`] (or `Vec<u8>` on WASM).
 #[cfg(not(target_arch = "wasm32"))]
 pub struct Mmap(memmap2::Mmap);
 
@@ -42,16 +40,10 @@ impl Deref for Mmap {
 
 impl AsRef<[u8]> for Mmap {
     fn as_ref(&self) -> &[u8] {
-        &*self.0
+        &self.0
     }
 }
 
-// SAFETY: On architectures other than WASM, mmap is used as backing storage. The address of this
-// memory map is stable. On WASM, `Vec<u8>` is used as backing storage. The `Mmap` type doesn't
-// export any function that can cause the `Vec` to be re-allocated. As such the address of the
-// bytes inside this `Vec` is stable.
-unsafe impl StableAddress for Mmap {}
-
 #[cfg(not(target_arch = "wasm32"))]
 pub struct MmapMut(memmap2::MmapMut);
 
diff --git a/compiler/rustc_data_structures/src/owned_slice.rs b/compiler/rustc_data_structures/src/owned_slice.rs
new file mode 100644
index 00000000000..048401f66c2
--- /dev/null
+++ b/compiler/rustc_data_structures/src/owned_slice.rs
@@ -0,0 +1,118 @@
+use std::{borrow::Borrow, ops::Deref};
+
+// Use our fake Send/Sync traits when on not parallel compiler,
+// so that `OwnedSlice` only implements/requires Send/Sync
+// for parallel compiler builds.
+use crate::sync::{Send, Sync};
+
+/// An owned slice.
+///
+/// This is similar to `Box<[u8]>` but allows slicing and using anything as the
+/// backing buffer.
+///
+/// See [`slice_owned`] for `OwnedSlice` construction and examples.
+///
+/// ---------------------------------------------------------------------------
+///
+/// This is essentially a replacement for `owning_ref` which is a lot simpler
+/// and even sound! 🌸
+pub struct OwnedSlice {
+    /// This is conceptually a `&'self.owner [u8]`.
+    bytes: *const [u8],
+
+    // +---------------------------------------+
+    // | We expect `dead_code` lint here,      |
+    // | because we don't want to accidentally |
+    // | touch the owner — otherwise the owner |
+    // | could invalidate out `bytes` pointer  |
+    // |                                       |
+    // | so be quiet                           |
+    // +----+  +-------------------------------+
+    //       \/
+    //      ⊂(´･◡･⊂ )∘˚˳° (I am the phantom remnant of #97770)
+    #[expect(dead_code)]
+    owner: Box<dyn Send + Sync>,
+}
+
+/// Makes an [`OwnedSlice`] out of an `owner` and a `slicer` function.
+///
+/// ## Examples
+///
+/// ```rust
+/// # use rustc_data_structures::owned_slice::{OwnedSlice, slice_owned};
+/// let vec = vec![1, 2, 3, 4];
+///
+/// // Identical to slicing via `&v[1..3]` but produces an owned slice
+/// let slice: OwnedSlice = slice_owned(vec, |v| &v[1..3]);
+/// assert_eq!(&*slice, [2, 3]);
+/// ```
+///
+/// ```rust
+/// # use rustc_data_structures::owned_slice::{OwnedSlice, slice_owned};
+/// # use std::ops::Deref;
+/// let vec = vec![1, 2, 3, 4];
+///
+/// // Identical to slicing via `&v[..]` but produces an owned slice
+/// let slice: OwnedSlice = slice_owned(vec, Deref::deref);
+/// assert_eq!(&*slice, [1, 2, 3, 4]);
+/// ```
+pub fn slice_owned<O, F>(owner: O, slicer: F) -> OwnedSlice
+where
+    O: Send + Sync + 'static,
+    F: FnOnce(&O) -> &[u8],
+{
+    try_slice_owned(owner, |x| Ok::<_, !>(slicer(x))).into_ok()
+}
+
+/// Makes an [`OwnedSlice`] out of an `owner` and a `slicer` function that can fail.
+///
+/// See [`slice_owned`] for the infallible version.
+pub fn try_slice_owned<O, F, E>(owner: O, slicer: F) -> Result<OwnedSlice, E>
+where
+    O: Send + Sync + 'static,
+    F: FnOnce(&O) -> Result<&[u8], E>,
+{
+    // We box the owner of the bytes, so it doesn't move.
+    //
+    // Since the owner does not move and we don't access it in any way
+    // before drop, there is nothing that can invalidate the bytes pointer.
+    //
+    // Thus, "extending" the lifetime of the reference returned from `F` is fine.
+    // We pretend that we pass it a reference that lives as long as the returned slice.
+    //
+    // N.B. the HRTB on the `slicer` is important — without it the caller could provide
+    // a short lived slice, unrelated to the owner.
+
+    let owner = Box::new(owner);
+    let bytes = slicer(&*owner)?;
+
+    Ok(OwnedSlice { bytes, owner })
+}
+
+impl Deref for OwnedSlice {
+    type Target = [u8];
+
+    #[inline]
+    fn deref(&self) -> &[u8] {
+        // Safety:
+        // `self.bytes` is valid per the construction in `slice_owned`
+        // (which is the only constructor)
+        unsafe { &*self.bytes }
+    }
+}
+
+impl Borrow<[u8]> for OwnedSlice {
+    #[inline]
+    fn borrow(&self) -> &[u8] {
+        self
+    }
+}
+
+// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Box<dyn Send + Sync>)`, which is `Send`
+unsafe impl Send for OwnedSlice {}
+
+// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Box<dyn Send + Sync>)`, which is `Sync`
+unsafe impl Sync for OwnedSlice {}
+
+#[cfg(test)]
+mod tests;
diff --git a/compiler/rustc_data_structures/src/owned_slice/tests.rs b/compiler/rustc_data_structures/src/owned_slice/tests.rs
new file mode 100644
index 00000000000..e715fb55362
--- /dev/null
+++ b/compiler/rustc_data_structures/src/owned_slice/tests.rs
@@ -0,0 +1,74 @@
+use std::{
+    ops::Deref,
+    sync::{
+        atomic::{self, AtomicBool},
+        Arc,
+    },
+};
+
+use crate::{
+    owned_slice::{slice_owned, try_slice_owned, OwnedSlice},
+    OnDrop,
+};
+
+#[test]
+fn smoke() {
+    let slice = slice_owned(vec![1, 2, 3, 4, 5, 6], Vec::as_slice);
+
+    assert_eq!(&*slice, [1, 2, 3, 4, 5, 6]);
+}
+
+#[test]
+fn static_storage() {
+    let slice = slice_owned(Box::new(String::from("what")), |_| b"bytes boo");
+
+    assert_eq!(&*slice, b"bytes boo");
+}
+
+#[test]
+fn slice_the_slice() {
+    let slice = slice_owned(vec![1, 2, 3, 4, 5, 6], Vec::as_slice);
+    let slice = slice_owned(slice, |s| &s[1..][..4]);
+    let slice = slice_owned(slice, |s| s);
+    let slice = slice_owned(slice, |s| &s[1..]);
+
+    assert_eq!(&*slice, &[1, 2, 3, 4, 5, 6][1..][..4][1..]);
+}
+
+#[test]
+fn try_and_fail() {
+    let res = try_slice_owned(vec![0], |v| v.get(12..).ok_or(()));
+
+    assert!(res.is_err());
+}
+
+#[test]
+fn boxed() {
+    // It's important that we don't cause UB because of `Box`'es uniqueness
+
+    let boxed: Box<[u8]> = vec![1, 1, 2, 3, 5, 8, 13, 21].into_boxed_slice();
+    let slice = slice_owned(boxed, Deref::deref);
+
+    assert_eq!(&*slice, [1, 1, 2, 3, 5, 8, 13, 21]);
+}
+
+#[test]
+fn drop_drops() {
+    let flag = Arc::new(AtomicBool::new(false));
+    let flag_prime = Arc::clone(&flag);
+    let d = OnDrop(move || flag_prime.store(true, atomic::Ordering::Relaxed));
+
+    let slice = slice_owned(d, |_| &[]);
+
+    assert_eq!(flag.load(atomic::Ordering::Relaxed), false);
+
+    drop(slice);
+
+    assert_eq!(flag.load(atomic::Ordering::Relaxed), true);
+}
+
+#[test]
+fn send_sync() {
+    crate::sync::assert_send::<OwnedSlice>();
+    crate::sync::assert_sync::<OwnedSlice>();
+}
diff --git a/compiler/rustc_data_structures/src/owning_ref/LICENSE b/compiler/rustc_data_structures/src/owning_ref/LICENSE
deleted file mode 100644
index dff72d1e432..00000000000
--- a/compiler/rustc_data_structures/src/owning_ref/LICENSE
+++ /dev/null
@@ -1,21 +0,0 @@
-The MIT License (MIT)
-
-Copyright (c) 2015 Marvin Löbel
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
diff --git a/compiler/rustc_data_structures/src/owning_ref/mod.rs b/compiler/rustc_data_structures/src/owning_ref/mod.rs
deleted file mode 100644
index d1d92b905b8..00000000000
--- a/compiler/rustc_data_structures/src/owning_ref/mod.rs
+++ /dev/null
@@ -1,1211 +0,0 @@
-#![warn(missing_docs)]
-
-/*!
-# An owning reference.
-
-This crate provides the _owning reference_ types `OwningRef` and `OwningRefMut`
-that enables it to bundle a reference together with the owner of the data it points to.
-This allows moving and dropping of an `OwningRef` without needing to recreate the reference.
-
-This can sometimes be useful because Rust borrowing rules normally prevent
-moving a type that has been moved from. For example, this kind of code gets rejected:
-
-```compile_fail,E0515
-fn return_owned_and_referenced<'a>() -> (Vec<u8>, &'a [u8]) {
-    let v = vec![1, 2, 3, 4];
-    let s = &v[1..3];
-    (v, s)
-}
-```
-
-Even though, from a memory-layout point of view, this can be entirely safe
-if the new location of the vector still lives longer than the lifetime `'a`
-of the reference because the backing allocation of the vector does not change.
-
-This library enables this safe usage by keeping the owner and the reference
-bundled together in a wrapper type that ensure that lifetime constraint:
-
-```
-# use rustc_data_structures::owning_ref::OwningRef;
-# fn main() {
-fn return_owned_and_referenced() -> OwningRef<Vec<u8>, [u8]> {
-    let v = vec![1, 2, 3, 4];
-    let or = OwningRef::new(v);
-    let or = or.map(|v| &v[1..3]);
-    or
-}
-# }
-```
-
-It works by requiring owner types to dereference to stable memory locations
-and preventing mutable access to root containers, which in practice requires heap allocation
-as provided by `Box<T>`, `Rc<T>`, etc.
-
-Also provided are typedefs for common owner type combinations,
-which allow for less verbose type signatures.
-For example, `BoxRef<T>` instead of `OwningRef<Box<T>, T>`.
-
-The crate also provides the more advanced `OwningHandle` type,
-which allows more freedom in bundling a dependent handle object
-along with the data it depends on, at the cost of some unsafe needed in the API.
-See the documentation around `OwningHandle` for more details.
-
-# Examples
-
-## Basics
-
-```
-use rustc_data_structures::owning_ref::BoxRef;
-
-fn main() {
-    // Create an array owned by a Box.
-    let arr = Box::new([1, 2, 3, 4]) as Box<[i32]>;
-
-    // Transfer into a BoxRef.
-    let arr: BoxRef<[i32]> = BoxRef::new(arr);
-    assert_eq!(&*arr, &[1, 2, 3, 4]);
-
-    // We can slice the array without losing ownership or changing type.
-    let arr: BoxRef<[i32]> = arr.map(|arr| &arr[1..3]);
-    assert_eq!(&*arr, &[2, 3]);
-
-    // Also works for Arc, Rc, String and Vec!
-}
-```
-
-## Caching a reference to a struct field
-
-```
-use rustc_data_structures::owning_ref::BoxRef;
-
-fn main() {
-    struct Foo {
-        tag: u32,
-        x: u16,
-        y: u16,
-        z: u16,
-    }
-    let foo = Foo { tag: 1, x: 100, y: 200, z: 300 };
-
-    let or = BoxRef::new(Box::new(foo)).map(|foo| {
-        match foo.tag {
-            0 => &foo.x,
-            1 => &foo.y,
-            2 => &foo.z,
-            _ => panic!(),
-        }
-    });
-
-    assert_eq!(*or, 200);
-}
-```
-
-## Caching a reference to an entry in a vector
-
-```
-use rustc_data_structures::owning_ref::VecRef;
-
-fn main() {
-    let v = VecRef::new(vec![1, 2, 3, 4, 5]).map(|v| &v[3]);
-    assert_eq!(*v, 4);
-}
-```
-
-## Caching a subslice of a String
-
-```
-use rustc_data_structures::owning_ref::StringRef;
-
-fn main() {
-    let s = StringRef::new("hello world".to_owned())
-        .map(|s| s.split(' ').nth(1).unwrap());
-
-    assert_eq!(&*s, "world");
-}
-```
-
-## Reference counted slices that share ownership of the backing storage
-
-```
-use rustc_data_structures::owning_ref::RcRef;
-use std::rc::Rc;
-
-fn main() {
-    let rc: RcRef<[i32]> = RcRef::new(Rc::new([1, 2, 3, 4]) as Rc<[i32]>);
-    assert_eq!(&*rc, &[1, 2, 3, 4]);
-
-    let rc_a: RcRef<[i32]> = rc.clone().map(|s| &s[0..2]);
-    let rc_b = rc.clone().map(|s| &s[1..3]);
-    let rc_c = rc.clone().map(|s| &s[2..4]);
-    assert_eq!(&*rc_a, &[1, 2]);
-    assert_eq!(&*rc_b, &[2, 3]);
-    assert_eq!(&*rc_c, &[3, 4]);
-
-    let rc_c_a = rc_c.clone().map(|s| &s[1]);
-    assert_eq!(&*rc_c_a, &4);
-}
-```
-
-## Atomic reference counted slices that share ownership of the backing storage
-
-```
-use rustc_data_structures::owning_ref::ArcRef;
-use std::sync::Arc;
-
-fn main() {
-    use std::thread;
-
-    fn par_sum(rc: ArcRef<[i32]>) -> i32 {
-        if rc.len() == 0 {
-            return 0;
-        } else if rc.len() == 1 {
-            return rc[0];
-        }
-        let mid = rc.len() / 2;
-        let left = rc.clone().map(|s| &s[..mid]);
-        let right = rc.map(|s| &s[mid..]);
-
-        let left = thread::spawn(move || par_sum(left));
-        let right = thread::spawn(move || par_sum(right));
-
-        left.join().unwrap() + right.join().unwrap()
-    }
-
-    let rc: Arc<[i32]> = Arc::new([1, 2, 3, 4]);
-    let rc: ArcRef<[i32]> = rc.into();
-
-    assert_eq!(par_sum(rc), 10);
-}
-```
-
-## References into RAII locks
-
-```
-use rustc_data_structures::owning_ref::RefRef;
-use std::cell::{RefCell, Ref};
-
-fn main() {
-    let refcell = RefCell::new((1, 2, 3, 4));
-    // Also works with Mutex and RwLock
-
-    let refref = {
-        let refref = RefRef::new(refcell.borrow()).map(|x| &x.3);
-        assert_eq!(*refref, 4);
-
-        // We move the RAII lock and the reference to one of
-        // the subfields in the data it guards here:
-        refref
-    };
-
-    assert_eq!(*refref, 4);
-
-    drop(refref);
-
-    assert_eq!(*refcell.borrow(), (1, 2, 3, 4));
-}
-```
-
-## Mutable reference
-
-When the owned container implements `DerefMut`, it is also possible to make
-a _mutable owning reference_. (e.g., with `Box`, `RefMut`, `MutexGuard`)
-
-```
-use rustc_data_structures::owning_ref::RefMutRefMut;
-use std::cell::{RefCell, RefMut};
-
-fn main() {
-    let refcell = RefCell::new((1, 2, 3, 4));
-
-    let mut refmut_refmut = {
-        let mut refmut_refmut = RefMutRefMut::new(refcell.borrow_mut()).map_mut(|x| &mut x.3);
-        assert_eq!(*refmut_refmut, 4);
-        *refmut_refmut *= 2;
-
-        refmut_refmut
-    };
-
-    assert_eq!(*refmut_refmut, 8);
-    *refmut_refmut *= 2;
-
-    drop(refmut_refmut);
-
-    assert_eq!(*refcell.borrow(), (1, 2, 3, 16));
-}
-```
-*/
-
-pub use stable_deref_trait::{
-    CloneStableDeref as CloneStableAddress, StableDeref as StableAddress,
-};
-use std::mem;
-
-/// An owning reference.
-///
-/// This wraps an owner `O` and a reference `&T` pointing
-/// at something reachable from `O::Target` while keeping
-/// the ability to move `self` around.
-///
-/// The owner is usually a pointer that points at some base type.
-///
-/// For more details and examples, see the module and method docs.
-pub struct OwningRef<O, T: ?Sized> {
-    owner: O,
-    reference: *const T,
-}
-
-/// An mutable owning reference.
-///
-/// This wraps an owner `O` and a reference `&mut T` pointing
-/// at something reachable from `O::Target` while keeping
-/// the ability to move `self` around.
-///
-/// The owner is usually a pointer that points at some base type.
-///
-/// For more details and examples, see the module and method docs.
-pub struct OwningRefMut<O, T: ?Sized> {
-    owner: O,
-    reference: *mut T,
-}
-
-/// Helper trait for an erased concrete type an owner dereferences to.
-/// This is used in form of a trait object for keeping
-/// something around to (virtually) call the destructor.
-pub trait Erased {}
-impl<T> Erased for T {}
-
-/// Helper trait for erasing the concrete type of what an owner dereferences to,
-/// for example `Box<T> -> Box<Erased>`. This would be unneeded with
-/// higher kinded types support in the language.
-#[allow(unused_lifetimes)]
-pub unsafe trait IntoErased<'a> {
-    /// Owner with the dereference type substituted to `Erased`.
-    type Erased;
-    /// Performs the type erasure.
-    fn into_erased(self) -> Self::Erased;
-}
-
-/// Helper trait for erasing the concrete type of what an owner dereferences to,
-/// for example `Box<T> -> Box<Erased + Send>`. This would be unneeded with
-/// higher kinded types support in the language.
-#[allow(unused_lifetimes)]
-pub unsafe trait IntoErasedSend<'a> {
-    /// Owner with the dereference type substituted to `Erased + Send`.
-    type Erased: Send;
-    /// Performs the type erasure.
-    fn into_erased_send(self) -> Self::Erased;
-}
-
-/// Helper trait for erasing the concrete type of what an owner dereferences to,
-/// for example `Box<T> -> Box<Erased + Send + Sync>`. This would be unneeded with
-/// higher kinded types support in the language.
-#[allow(unused_lifetimes)]
-pub unsafe trait IntoErasedSendSync<'a> {
-    /// Owner with the dereference type substituted to `Erased + Send + Sync`.
-    type Erased: Send + Sync;
-    /// Performs the type erasure.
-    fn into_erased_send_sync(self) -> Self::Erased;
-}
-
-/////////////////////////////////////////////////////////////////////////////
-// OwningRef
-/////////////////////////////////////////////////////////////////////////////
-
-impl<O, T: ?Sized> OwningRef<O, T> {
-    /// Creates a new owning reference from an owner
-    /// initialized to the direct dereference of it.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::OwningRef;
-    ///
-    /// fn main() {
-    ///     let owning_ref = OwningRef::new(Box::new(42));
-    ///     assert_eq!(*owning_ref, 42);
-    /// }
-    /// ```
-    pub fn new(o: O) -> Self
-    where
-        O: StableAddress,
-        O: Deref<Target = T>,
-    {
-        OwningRef { reference: &*o, owner: o }
-    }
-
-    /// Like `new`, but doesn’t require `O` to implement the `StableAddress` trait.
-    /// Instead, the caller is responsible to make the same promises as implementing the trait.
-    ///
-    /// This is useful for cases where coherence rules prevents implementing the trait
-    /// without adding a dependency to this crate in a third-party library.
-    pub unsafe fn new_assert_stable_address(o: O) -> Self
-    where
-        O: Deref<Target = T>,
-    {
-        OwningRef { reference: &*o, owner: o }
-    }
-
-    /// Converts `self` into a new owning reference that points at something reachable
-    /// from the previous one.
-    ///
-    /// This can be a reference to a field of `U`, something reachable from a field of
-    /// `U`, or even something unrelated with a `'static` lifetime.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::OwningRef;
-    ///
-    /// fn main() {
-    ///     let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4]));
-    ///
-    ///     // create an owning reference that points at the
-    ///     // third element of the array.
-    ///     let owning_ref = owning_ref.map(|array| &array[2]);
-    ///     assert_eq!(*owning_ref, 3);
-    /// }
-    /// ```
-    pub fn map<F, U: ?Sized>(self, f: F) -> OwningRef<O, U>
-    where
-        O: StableAddress,
-        F: FnOnce(&T) -> &U,
-    {
-        OwningRef { reference: f(&self), owner: self.owner }
-    }
-
-    /// Tries to convert `self` into a new owning reference that points
-    /// at something reachable from the previous one.
-    ///
-    /// This can be a reference to a field of `U`, something reachable from a field of
-    /// `U`, or even something unrelated with a `'static` lifetime.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::OwningRef;
-    ///
-    /// fn main() {
-    ///     let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4]));
-    ///
-    ///     // create an owning reference that points at the
-    ///     // third element of the array.
-    ///     let owning_ref = owning_ref.try_map(|array| {
-    ///         if array[2] == 3 { Ok(&array[2]) } else { Err(()) }
-    ///     });
-    ///     assert_eq!(*owning_ref.unwrap(), 3);
-    /// }
-    /// ```
-    pub fn try_map<F, U: ?Sized, E>(self, f: F) -> Result<OwningRef<O, U>, E>
-    where
-        O: StableAddress,
-        F: FnOnce(&T) -> Result<&U, E>,
-    {
-        Ok(OwningRef { reference: f(&self)?, owner: self.owner })
-    }
-
-    /// Converts `self` into a new owning reference with a different owner type.
-    ///
-    /// The new owner type needs to still contain the original owner in some way
-    /// so that the reference into it remains valid. This function is marked unsafe
-    /// because the user needs to manually uphold this guarantee.
-    pub unsafe fn map_owner<F, P>(self, f: F) -> OwningRef<P, T>
-    where
-        O: StableAddress,
-        P: StableAddress,
-        F: FnOnce(O) -> P,
-    {
-        OwningRef { reference: self.reference, owner: f(self.owner) }
-    }
-
-    /// Converts `self` into a new owning reference where the owner is wrapped
-    /// in an additional `Box<O>`.
-    ///
-    /// This can be used to safely erase the owner of any `OwningRef<O, T>`
-    /// to an `OwningRef<Box<Erased>, T>`.
-    pub fn map_owner_box(self) -> OwningRef<Box<O>, T> {
-        OwningRef { reference: self.reference, owner: Box::new(self.owner) }
-    }
-
-    /// Erases the concrete base type of the owner with a trait object.
-    ///
-    /// This allows mixing of owned references with different owner base types.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::{OwningRef, Erased};
-    ///
-    /// fn main() {
-    ///     // N.B., using the concrete types here for explicitness.
-    ///     // For less verbose code type aliases like `BoxRef` are provided.
-    ///
-    ///     let owning_ref_a: OwningRef<Box<[i32; 4]>, [i32; 4]>
-    ///         = OwningRef::new(Box::new([1, 2, 3, 4]));
-    ///
-    ///     let owning_ref_b: OwningRef<Box<Vec<(i32, bool)>>, Vec<(i32, bool)>>
-    ///         = OwningRef::new(Box::new(vec![(0, false), (1, true)]));
-    ///
-    ///     let owning_ref_a: OwningRef<Box<[i32; 4]>, i32>
-    ///         = owning_ref_a.map(|a| &a[0]);
-    ///
-    ///     let owning_ref_b: OwningRef<Box<Vec<(i32, bool)>>, i32>
-    ///         = owning_ref_b.map(|a| &a[1].0);
-    ///
-    ///     let owning_refs: [OwningRef<Box<dyn Erased>, i32>; 2]
-    ///         = [owning_ref_a.erase_owner(), owning_ref_b.erase_owner()];
-    ///
-    ///     assert_eq!(*owning_refs[0], 1);
-    ///     assert_eq!(*owning_refs[1], 1);
-    /// }
-    /// ```
-    pub fn erase_owner<'a>(self) -> OwningRef<O::Erased, T>
-    where
-        O: IntoErased<'a>,
-    {
-        OwningRef { reference: self.reference, owner: self.owner.into_erased() }
-    }
-
-    /// Erases the concrete base type of the owner with a trait object which implements `Send`.
-    ///
-    /// This allows mixing of owned references with different owner base types.
-    pub fn erase_send_owner<'a>(self) -> OwningRef<O::Erased, T>
-    where
-        O: IntoErasedSend<'a>,
-    {
-        OwningRef { reference: self.reference, owner: self.owner.into_erased_send() }
-    }
-
-    /// Erases the concrete base type of the owner with a trait object
-    /// which implements `Send` and `Sync`.
-    ///
-    /// This allows mixing of owned references with different owner base types.
-    pub fn erase_send_sync_owner<'a>(self) -> OwningRef<O::Erased, T>
-    where
-        O: IntoErasedSendSync<'a>,
-    {
-        OwningRef { reference: self.reference, owner: self.owner.into_erased_send_sync() }
-    }
-
-    // UNIMPLEMENTED: wrap_owner
-
-    // FIXME: Naming convention?
-    /// A getter for the underlying owner.
-    pub fn owner(&self) -> &O {
-        &self.owner
-    }
-
-    // FIXME: Naming convention?
-    /// Discards the reference and retrieves the owner.
-    pub fn into_inner(self) -> O {
-        self.owner
-    }
-}
-
-impl<O, T: ?Sized> OwningRefMut<O, T> {
-    /// Creates a new owning reference from an owner
-    /// initialized to the direct dereference of it.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::OwningRefMut;
-    ///
-    /// fn main() {
-    ///     let owning_ref_mut = OwningRefMut::new(Box::new(42));
-    ///     assert_eq!(*owning_ref_mut, 42);
-    /// }
-    /// ```
-    pub fn new(mut o: O) -> Self
-    where
-        O: StableAddress,
-        O: DerefMut<Target = T>,
-    {
-        OwningRefMut { reference: &mut *o, owner: o }
-    }
-
-    /// Like `new`, but doesn’t require `O` to implement the `StableAddress` trait.
-    /// Instead, the caller is responsible to make the same promises as implementing the trait.
-    ///
-    /// This is useful for cases where coherence rules prevents implementing the trait
-    /// without adding a dependency to this crate in a third-party library.
-    pub unsafe fn new_assert_stable_address(mut o: O) -> Self
-    where
-        O: DerefMut<Target = T>,
-    {
-        OwningRefMut { reference: &mut *o, owner: o }
-    }
-
-    /// Converts `self` into a new _shared_ owning reference that points at
-    /// something reachable from the previous one.
-    ///
-    /// This can be a reference to a field of `U`, something reachable from a field of
-    /// `U`, or even something unrelated with a `'static` lifetime.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::OwningRefMut;
-    ///
-    /// fn main() {
-    ///     let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4]));
-    ///
-    ///     // create an owning reference that points at the
-    ///     // third element of the array.
-    ///     let owning_ref = owning_ref_mut.map(|array| &array[2]);
-    ///     assert_eq!(*owning_ref, 3);
-    /// }
-    /// ```
-    pub fn map<F, U: ?Sized>(mut self, f: F) -> OwningRef<O, U>
-    where
-        O: StableAddress,
-        F: FnOnce(&mut T) -> &U,
-    {
-        OwningRef { reference: f(&mut self), owner: self.owner }
-    }
-
-    /// Converts `self` into a new _mutable_ owning reference that points at
-    /// something reachable from the previous one.
-    ///
-    /// This can be a reference to a field of `U`, something reachable from a field of
-    /// `U`, or even something unrelated with a `'static` lifetime.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::OwningRefMut;
-    ///
-    /// fn main() {
-    ///     let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4]));
-    ///
-    ///     // create an owning reference that points at the
-    ///     // third element of the array.
-    ///     let owning_ref_mut = owning_ref_mut.map_mut(|array| &mut array[2]);
-    ///     assert_eq!(*owning_ref_mut, 3);
-    /// }
-    /// ```
-    pub fn map_mut<F, U: ?Sized>(mut self, f: F) -> OwningRefMut<O, U>
-    where
-        O: StableAddress,
-        F: FnOnce(&mut T) -> &mut U,
-    {
-        OwningRefMut { reference: f(&mut self), owner: self.owner }
-    }
-
-    /// Tries to convert `self` into a new _shared_ owning reference that points
-    /// at something reachable from the previous one.
-    ///
-    /// This can be a reference to a field of `U`, something reachable from a field of
-    /// `U`, or even something unrelated with a `'static` lifetime.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::OwningRefMut;
-    ///
-    /// fn main() {
-    ///     let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4]));
-    ///
-    ///     // create an owning reference that points at the
-    ///     // third element of the array.
-    ///     let owning_ref = owning_ref_mut.try_map(|array| {
-    ///         if array[2] == 3 { Ok(&array[2]) } else { Err(()) }
-    ///     });
-    ///     assert_eq!(*owning_ref.unwrap(), 3);
-    /// }
-    /// ```
-    pub fn try_map<F, U: ?Sized, E>(mut self, f: F) -> Result<OwningRef<O, U>, E>
-    where
-        O: StableAddress,
-        F: FnOnce(&mut T) -> Result<&U, E>,
-    {
-        Ok(OwningRef { reference: f(&mut self)?, owner: self.owner })
-    }
-
-    /// Tries to convert `self` into a new _mutable_ owning reference that points
-    /// at something reachable from the previous one.
-    ///
-    /// This can be a reference to a field of `U`, something reachable from a field of
-    /// `U`, or even something unrelated with a `'static` lifetime.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::OwningRefMut;
-    ///
-    /// fn main() {
-    ///     let owning_ref_mut = OwningRefMut::new(Box::new([1, 2, 3, 4]));
-    ///
-    ///     // create an owning reference that points at the
-    ///     // third element of the array.
-    ///     let owning_ref_mut = owning_ref_mut.try_map_mut(|array| {
-    ///         if array[2] == 3 { Ok(&mut array[2]) } else { Err(()) }
-    ///     });
-    ///     assert_eq!(*owning_ref_mut.unwrap(), 3);
-    /// }
-    /// ```
-    pub fn try_map_mut<F, U: ?Sized, E>(mut self, f: F) -> Result<OwningRefMut<O, U>, E>
-    where
-        O: StableAddress,
-        F: FnOnce(&mut T) -> Result<&mut U, E>,
-    {
-        Ok(OwningRefMut { reference: f(&mut self)?, owner: self.owner })
-    }
-
-    /// Converts `self` into a new owning reference with a different owner type.
-    ///
-    /// The new owner type needs to still contain the original owner in some way
-    /// so that the reference into it remains valid. This function is marked unsafe
-    /// because the user needs to manually uphold this guarantee.
-    pub unsafe fn map_owner<F, P>(self, f: F) -> OwningRefMut<P, T>
-    where
-        O: StableAddress,
-        P: StableAddress,
-        F: FnOnce(O) -> P,
-    {
-        OwningRefMut { reference: self.reference, owner: f(self.owner) }
-    }
-
-    /// Converts `self` into a new owning reference where the owner is wrapped
-    /// in an additional `Box<O>`.
-    ///
-    /// This can be used to safely erase the owner of any `OwningRefMut<O, T>`
-    /// to an `OwningRefMut<Box<Erased>, T>`.
-    pub fn map_owner_box(self) -> OwningRefMut<Box<O>, T> {
-        OwningRefMut { reference: self.reference, owner: Box::new(self.owner) }
-    }
-
-    /// Erases the concrete base type of the owner with a trait object.
-    ///
-    /// This allows mixing of owned references with different owner base types.
-    ///
-    /// # Example
-    /// ```
-    /// use rustc_data_structures::owning_ref::{OwningRefMut, Erased};
-    ///
-    /// fn main() {
-    ///     // N.B., using the concrete types here for explicitness.
-    ///     // For less verbose code type aliases like `BoxRef` are provided.
-    ///
-    ///     let owning_ref_mut_a: OwningRefMut<Box<[i32; 4]>, [i32; 4]>
-    ///         = OwningRefMut::new(Box::new([1, 2, 3, 4]));
-    ///
-    ///     let owning_ref_mut_b: OwningRefMut<Box<Vec<(i32, bool)>>, Vec<(i32, bool)>>
-    ///         = OwningRefMut::new(Box::new(vec![(0, false), (1, true)]));
-    ///
-    ///     let owning_ref_mut_a: OwningRefMut<Box<[i32; 4]>, i32>
-    ///         = owning_ref_mut_a.map_mut(|a| &mut a[0]);
-    ///
-    ///     let owning_ref_mut_b: OwningRefMut<Box<Vec<(i32, bool)>>, i32>
-    ///         = owning_ref_mut_b.map_mut(|a| &mut a[1].0);
-    ///
-    ///     let owning_refs_mut: [OwningRefMut<Box<dyn Erased>, i32>; 2]
-    ///         = [owning_ref_mut_a.erase_owner(), owning_ref_mut_b.erase_owner()];
-    ///
-    ///     assert_eq!(*owning_refs_mut[0], 1);
-    ///     assert_eq!(*owning_refs_mut[1], 1);
-    /// }
-    /// ```
-    pub fn erase_owner<'a>(self) -> OwningRefMut<O::Erased, T>
-    where
-        O: IntoErased<'a>,
-    {
-        OwningRefMut { reference: self.reference, owner: self.owner.into_erased() }
-    }
-
-    // UNIMPLEMENTED: wrap_owner
-
-    // FIXME: Naming convention?
-    /// A getter for the underlying owner.
-    pub fn owner(&self) -> &O {
-        &self.owner
-    }
-
-    // FIXME: Naming convention?
-    /// Discards the reference and retrieves the owner.
-    pub fn into_inner(self) -> O {
-        self.owner
-    }
-}
-
-/////////////////////////////////////////////////////////////////////////////
-// OwningHandle
-/////////////////////////////////////////////////////////////////////////////
-
-use std::ops::{Deref, DerefMut};
-
-/// `OwningHandle` is a complement to `OwningRef`. Where `OwningRef` allows
-/// consumers to pass around an owned object and a dependent reference,
-/// `OwningHandle` contains an owned object and a dependent _object_.
-///
-/// `OwningHandle` can encapsulate a `RefMut` along with its associated
-/// `RefCell`, or an `RwLockReadGuard` along with its associated `RwLock`.
-/// However, the API is completely generic and there are no restrictions on
-/// what types of owning and dependent objects may be used.
-///
-/// `OwningHandle` is created by passing an owner object (which dereferences
-/// to a stable address) along with a callback which receives a pointer to
-/// that stable location. The callback may then dereference the pointer and
-/// mint a dependent object, with the guarantee that the returned object will
-/// not outlive the referent of the pointer.
-///
-/// Since the callback needs to dereference a raw pointer, it requires `unsafe`
-/// code. To avoid forcing this unsafety on most callers, the `ToHandle` trait is
-/// implemented for common data structures. Types that implement `ToHandle` can
-/// be wrapped into an `OwningHandle` without passing a callback.
-pub struct OwningHandle<O, H>
-where
-    O: StableAddress,
-    H: Deref,
-{
-    handle: H,
-    _owner: O,
-}
-
-impl<O, H> Deref for OwningHandle<O, H>
-where
-    O: StableAddress,
-    H: Deref,
-{
-    type Target = H::Target;
-    fn deref(&self) -> &H::Target {
-        self.handle.deref()
-    }
-}
-
-unsafe impl<O, H> StableAddress for OwningHandle<O, H>
-where
-    O: StableAddress,
-    H: StableAddress,
-{
-}
-
-impl<O, H> DerefMut for OwningHandle<O, H>
-where
-    O: StableAddress,
-    H: DerefMut,
-{
-    fn deref_mut(&mut self) -> &mut H::Target {
-        self.handle.deref_mut()
-    }
-}
-
-/// Trait to implement the conversion of owner to handle for common types.
-pub trait ToHandle {
-    /// The type of handle to be encapsulated by the OwningHandle.
-    type Handle: Deref;
-
-    /// Given an appropriately-long-lived pointer to ourselves, create a
-    /// handle to be encapsulated by the `OwningHandle`.
-    unsafe fn to_handle(x: *const Self) -> Self::Handle;
-}
-
-/// Trait to implement the conversion of owner to mutable handle for common types.
-pub trait ToHandleMut {
-    /// The type of handle to be encapsulated by the OwningHandle.
-    type HandleMut: DerefMut;
-
-    /// Given an appropriately-long-lived pointer to ourselves, create a
-    /// mutable handle to be encapsulated by the `OwningHandle`.
-    unsafe fn to_handle_mut(x: *const Self) -> Self::HandleMut;
-}
-
-impl<O, H> OwningHandle<O, H>
-where
-    O: StableAddress<Target: ToHandle<Handle = H>>,
-    H: Deref,
-{
-    /// Creates a new `OwningHandle` for a type that implements `ToHandle`. For types
-    /// that don't implement `ToHandle`, callers may invoke `new_with_fn`, which accepts
-    /// a callback to perform the conversion.
-    pub fn new(o: O) -> Self {
-        OwningHandle::new_with_fn(o, |x| unsafe { O::Target::to_handle(x) })
-    }
-}
-
-impl<O, H> OwningHandle<O, H>
-where
-    O: StableAddress<Target: ToHandleMut<HandleMut = H>>,
-    H: DerefMut,
-{
-    /// Creates a new mutable `OwningHandle` for a type that implements `ToHandleMut`.
-    pub fn new_mut(o: O) -> Self {
-        OwningHandle::new_with_fn(o, |x| unsafe { O::Target::to_handle_mut(x) })
-    }
-}
-
-impl<O, H> OwningHandle<O, H>
-where
-    O: StableAddress,
-    H: Deref,
-{
-    /// Creates a new OwningHandle. The provided callback will be invoked with
-    /// a pointer to the object owned by `o`, and the returned value is stored
-    /// as the object to which this `OwningHandle` will forward `Deref` and
-    /// `DerefMut`.
-    pub fn new_with_fn<F>(o: O, f: F) -> Self
-    where
-        F: FnOnce(*const O::Target) -> H,
-    {
-        let h: H;
-        {
-            h = f(o.deref() as *const O::Target);
-        }
-
-        OwningHandle { handle: h, _owner: o }
-    }
-
-    /// Creates a new OwningHandle. The provided callback will be invoked with
-    /// a pointer to the object owned by `o`, and the returned value is stored
-    /// as the object to which this `OwningHandle` will forward `Deref` and
-    /// `DerefMut`.
-    pub fn try_new<F, E>(o: O, f: F) -> Result<Self, E>
-    where
-        F: FnOnce(*const O::Target) -> Result<H, E>,
-    {
-        let h: H;
-        {
-            h = f(o.deref() as *const O::Target)?;
-        }
-
-        Ok(OwningHandle { handle: h, _owner: o })
-    }
-}
-
-/////////////////////////////////////////////////////////////////////////////
-// std traits
-/////////////////////////////////////////////////////////////////////////////
-
-use std::borrow::Borrow;
-use std::cmp::Ordering;
-use std::fmt::{self, Debug};
-use std::hash::{Hash, Hasher};
-
-impl<O, T: ?Sized> Deref for OwningRef<O, T> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        unsafe { &*self.reference }
-    }
-}
-
-impl<O, T: ?Sized> Deref for OwningRefMut<O, T> {
-    type Target = T;
-
-    fn deref(&self) -> &T {
-        unsafe { &*self.reference }
-    }
-}
-
-impl<O, T: ?Sized> DerefMut for OwningRefMut<O, T> {
-    fn deref_mut(&mut self) -> &mut T {
-        unsafe { &mut *self.reference }
-    }
-}
-
-unsafe impl<O, T: ?Sized> StableAddress for OwningRef<O, T> {}
-
-impl<O, T: ?Sized> AsRef<T> for OwningRef<O, T> {
-    fn as_ref(&self) -> &T {
-        self
-    }
-}
-
-impl<O, T: ?Sized> AsRef<T> for OwningRefMut<O, T> {
-    fn as_ref(&self) -> &T {
-        self
-    }
-}
-
-impl<O, T: ?Sized> AsMut<T> for OwningRefMut<O, T> {
-    fn as_mut(&mut self) -> &mut T {
-        self
-    }
-}
-
-impl<O, T: ?Sized> Borrow<T> for OwningRef<O, T> {
-    fn borrow(&self) -> &T {
-        self
-    }
-}
-
-impl<O, T: ?Sized> From<O> for OwningRef<O, T>
-where
-    O: StableAddress,
-    O: Deref<Target = T>,
-{
-    fn from(owner: O) -> Self {
-        OwningRef::new(owner)
-    }
-}
-
-impl<O, T: ?Sized> From<O> for OwningRefMut<O, T>
-where
-    O: StableAddress,
-    O: DerefMut<Target = T>,
-{
-    fn from(owner: O) -> Self {
-        OwningRefMut::new(owner)
-    }
-}
-
-impl<O, T: ?Sized> From<OwningRefMut<O, T>> for OwningRef<O, T>
-where
-    O: StableAddress,
-    O: DerefMut<Target = T>,
-{
-    fn from(other: OwningRefMut<O, T>) -> Self {
-        OwningRef { owner: other.owner, reference: other.reference }
-    }
-}
-
-// ^ FIXME: Is an Into impl for calling into_inner() possible as well?
-
-impl<O, T: ?Sized> Debug for OwningRef<O, T>
-where
-    O: Debug,
-    T: Debug,
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "OwningRef {{ owner: {:?}, reference: {:?} }}", self.owner(), &**self)
-    }
-}
-
-impl<O, T: ?Sized> Debug for OwningRefMut<O, T>
-where
-    O: Debug,
-    T: Debug,
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "OwningRefMut {{ owner: {:?}, reference: {:?} }}", self.owner(), &**self)
-    }
-}
-
-impl<O, T: ?Sized> Clone for OwningRef<O, T>
-where
-    O: CloneStableAddress,
-{
-    fn clone(&self) -> Self {
-        OwningRef { owner: self.owner.clone(), reference: self.reference }
-    }
-}
-
-unsafe impl<O, T: ?Sized> CloneStableAddress for OwningRef<O, T> where O: CloneStableAddress {}
-
-unsafe impl<O, T: ?Sized> Send for OwningRef<O, T>
-where
-    O: Send,
-    for<'a> &'a T: Send,
-{
-}
-unsafe impl<O, T: ?Sized> Sync for OwningRef<O, T>
-where
-    O: Sync,
-    for<'a> &'a T: Sync,
-{
-}
-
-unsafe impl<O, T: ?Sized> Send for OwningRefMut<O, T>
-where
-    O: Send,
-    for<'a> &'a mut T: Send,
-{
-}
-unsafe impl<O, T: ?Sized> Sync for OwningRefMut<O, T>
-where
-    O: Sync,
-    for<'a> &'a mut T: Sync,
-{
-}
-
-impl Debug for dyn Erased {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "<Erased>",)
-    }
-}
-
-impl<O, T: ?Sized> PartialEq for OwningRef<O, T>
-where
-    T: PartialEq,
-{
-    fn eq(&self, other: &Self) -> bool {
-        self.deref().eq(other.deref())
-    }
-}
-
-impl<O, T: ?Sized> Eq for OwningRef<O, T> where T: Eq {}
-
-impl<O, T: ?Sized> PartialOrd for OwningRef<O, T>
-where
-    T: PartialOrd,
-{
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        self.deref().partial_cmp(other.deref())
-    }
-}
-
-impl<O, T: ?Sized> Ord for OwningRef<O, T>
-where
-    T: Ord,
-{
-    fn cmp(&self, other: &Self) -> Ordering {
-        self.deref().cmp(other.deref())
-    }
-}
-
-impl<O, T: ?Sized> Hash for OwningRef<O, T>
-where
-    T: Hash,
-{
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.deref().hash(state);
-    }
-}
-
-impl<O, T: ?Sized> PartialEq for OwningRefMut<O, T>
-where
-    T: PartialEq,
-{
-    fn eq(&self, other: &Self) -> bool {
-        self.deref().eq(other.deref())
-    }
-}
-
-impl<O, T: ?Sized> Eq for OwningRefMut<O, T> where T: Eq {}
-
-impl<O, T: ?Sized> PartialOrd for OwningRefMut<O, T>
-where
-    T: PartialOrd,
-{
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        self.deref().partial_cmp(other.deref())
-    }
-}
-
-impl<O, T: ?Sized> Ord for OwningRefMut<O, T>
-where
-    T: Ord,
-{
-    fn cmp(&self, other: &Self) -> Ordering {
-        self.deref().cmp(other.deref())
-    }
-}
-
-impl<O, T: ?Sized> Hash for OwningRefMut<O, T>
-where
-    T: Hash,
-{
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.deref().hash(state);
-    }
-}
-
-/////////////////////////////////////////////////////////////////////////////
-// std types integration and convenience type defs
-/////////////////////////////////////////////////////////////////////////////
-
-use std::cell::{Ref, RefCell, RefMut};
-use std::rc::Rc;
-use std::sync::Arc;
-use std::sync::{MutexGuard, RwLockReadGuard, RwLockWriteGuard};
-
-impl<T: 'static> ToHandle for RefCell<T> {
-    type Handle = Ref<'static, T>;
-    unsafe fn to_handle(x: *const Self) -> Self::Handle {
-        (*x).borrow()
-    }
-}
-
-impl<T: 'static> ToHandleMut for RefCell<T> {
-    type HandleMut = RefMut<'static, T>;
-    unsafe fn to_handle_mut(x: *const Self) -> Self::HandleMut {
-        (*x).borrow_mut()
-    }
-}
-
-// N.B., implementing ToHandle{,Mut} for Mutex and RwLock requires a decision
-// about which handle creation to use (i.e., read() vs try_read()) as well as
-// what to do with error results.
-
-/// Typedef of an owning reference that uses a `Box` as the owner.
-pub type BoxRef<T, U = T> = OwningRef<Box<T>, U>;
-/// Typedef of an owning reference that uses a `Vec` as the owner.
-pub type VecRef<T, U = T> = OwningRef<Vec<T>, U>;
-/// Typedef of an owning reference that uses a `String` as the owner.
-pub type StringRef = OwningRef<String, str>;
-
-/// Typedef of an owning reference that uses an `Rc` as the owner.
-pub type RcRef<T, U = T> = OwningRef<Rc<T>, U>;
-/// Typedef of an owning reference that uses an `Arc` as the owner.
-pub type ArcRef<T, U = T> = OwningRef<Arc<T>, U>;
-
-/// Typedef of an owning reference that uses a `Ref` as the owner.
-pub type RefRef<'a, T, U = T> = OwningRef<Ref<'a, T>, U>;
-/// Typedef of an owning reference that uses a `RefMut` as the owner.
-pub type RefMutRef<'a, T, U = T> = OwningRef<RefMut<'a, T>, U>;
-/// Typedef of an owning reference that uses a `MutexGuard` as the owner.
-pub type MutexGuardRef<'a, T, U = T> = OwningRef<MutexGuard<'a, T>, U>;
-/// Typedef of an owning reference that uses an `RwLockReadGuard` as the owner.
-pub type RwLockReadGuardRef<'a, T, U = T> = OwningRef<RwLockReadGuard<'a, T>, U>;
-/// Typedef of an owning reference that uses an `RwLockWriteGuard` as the owner.
-pub type RwLockWriteGuardRef<'a, T, U = T> = OwningRef<RwLockWriteGuard<'a, T>, U>;
-
-/// Typedef of a mutable owning reference that uses a `Box` as the owner.
-pub type BoxRefMut<T, U = T> = OwningRefMut<Box<T>, U>;
-/// Typedef of a mutable owning reference that uses a `Vec` as the owner.
-pub type VecRefMut<T, U = T> = OwningRefMut<Vec<T>, U>;
-/// Typedef of a mutable owning reference that uses a `String` as the owner.
-pub type StringRefMut = OwningRefMut<String, str>;
-
-/// Typedef of a mutable owning reference that uses a `RefMut` as the owner.
-pub type RefMutRefMut<'a, T, U = T> = OwningRefMut<RefMut<'a, T>, U>;
-/// Typedef of a mutable owning reference that uses a `MutexGuard` as the owner.
-pub type MutexGuardRefMut<'a, T, U = T> = OwningRefMut<MutexGuard<'a, T>, U>;
-/// Typedef of a mutable owning reference that uses an `RwLockWriteGuard` as the owner.
-pub type RwLockWriteGuardRefMut<'a, T, U = T> = OwningRef<RwLockWriteGuard<'a, T>, U>;
-
-unsafe impl<'a, T: 'a> IntoErased<'a> for Box<T> {
-    type Erased = Box<dyn Erased + 'a>;
-    fn into_erased(self) -> Self::Erased {
-        self
-    }
-}
-unsafe impl<'a, T: 'a> IntoErased<'a> for Rc<T> {
-    type Erased = Rc<dyn Erased + 'a>;
-    fn into_erased(self) -> Self::Erased {
-        self
-    }
-}
-unsafe impl<'a, T: 'a> IntoErased<'a> for Arc<T> {
-    type Erased = Arc<dyn Erased + 'a>;
-    fn into_erased(self) -> Self::Erased {
-        self
-    }
-}
-
-unsafe impl<'a, T: Send + 'a> IntoErasedSend<'a> for Box<T> {
-    type Erased = Box<dyn Erased + Send + 'a>;
-    fn into_erased_send(self) -> Self::Erased {
-        self
-    }
-}
-
-unsafe impl<'a, T: Send + 'a> IntoErasedSendSync<'a> for Box<T> {
-    type Erased = Box<dyn Erased + Sync + Send + 'a>;
-    fn into_erased_send_sync(self) -> Self::Erased {
-        let result: Box<dyn Erased + Send + 'a> = self;
-        // This is safe since Erased can always implement Sync
-        // Only the destructor is available and it takes &mut self
-        unsafe { mem::transmute(result) }
-    }
-}
-
-unsafe impl<'a, T: Send + Sync + 'a> IntoErasedSendSync<'a> for Arc<T> {
-    type Erased = Arc<dyn Erased + Send + Sync + 'a>;
-    fn into_erased_send_sync(self) -> Self::Erased {
-        self
-    }
-}
-
-/// Typedef of an owning reference that uses an erased `Box` as the owner.
-pub type ErasedBoxRef<U> = OwningRef<Box<dyn Erased>, U>;
-/// Typedef of an owning reference that uses an erased `Rc` as the owner.
-pub type ErasedRcRef<U> = OwningRef<Rc<dyn Erased>, U>;
-/// Typedef of an owning reference that uses an erased `Arc` as the owner.
-pub type ErasedArcRef<U> = OwningRef<Arc<dyn Erased>, U>;
-
-/// Typedef of a mutable owning reference that uses an erased `Box` as the owner.
-pub type ErasedBoxRefMut<U> = OwningRefMut<Box<dyn Erased>, U>;
-
-#[cfg(test)]
-mod tests;
diff --git a/compiler/rustc_data_structures/src/owning_ref/tests.rs b/compiler/rustc_data_structures/src/owning_ref/tests.rs
deleted file mode 100644
index a9b187c4ce0..00000000000
--- a/compiler/rustc_data_structures/src/owning_ref/tests.rs
+++ /dev/null
@@ -1,711 +0,0 @@
-// FIXME: owning_ref is not sound under stacked borrows. Preferably, get rid of it.
-#[cfg(not(miri))]
-mod owning_ref {
-    use super::super::OwningRef;
-    use super::super::{BoxRef, Erased, ErasedBoxRef, RcRef};
-    use std::cmp::Ordering;
-    use std::collections::hash_map::DefaultHasher;
-    use std::collections::HashMap;
-    use std::hash::{Hash, Hasher};
-    use std::rc::Rc;
-
-    #[derive(Debug, PartialEq)]
-    struct Example(u32, String, [u8; 3]);
-    fn example() -> Example {
-        Example(42, "hello world".to_string(), [1, 2, 3])
-    }
-
-    #[test]
-    fn new_deref() {
-        let or: OwningRef<Box<()>, ()> = OwningRef::new(Box::new(()));
-        assert_eq!(&*or, &());
-    }
-
-    #[test]
-    fn into() {
-        let or: OwningRef<Box<()>, ()> = Box::new(()).into();
-        assert_eq!(&*or, &());
-    }
-
-    #[test]
-    fn map_offset_ref() {
-        let or: BoxRef<Example> = Box::new(example()).into();
-        let or: BoxRef<_, u32> = or.map(|x| &x.0);
-        assert_eq!(&*or, &42);
-
-        let or: BoxRef<Example> = Box::new(example()).into();
-        let or: BoxRef<_, u8> = or.map(|x| &x.2[1]);
-        assert_eq!(&*or, &2);
-    }
-
-    #[test]
-    fn map_heap_ref() {
-        let or: BoxRef<Example> = Box::new(example()).into();
-        let or: BoxRef<_, str> = or.map(|x| &x.1[..5]);
-        assert_eq!(&*or, "hello");
-    }
-
-    #[test]
-    fn map_static_ref() {
-        let or: BoxRef<()> = Box::new(()).into();
-        let or: BoxRef<_, str> = or.map(|_| "hello");
-        assert_eq!(&*or, "hello");
-    }
-
-    #[test]
-    fn map_chained() {
-        let or: BoxRef<String> = Box::new(example().1).into();
-        let or: BoxRef<_, str> = or.map(|x| &x[1..5]);
-        let or: BoxRef<_, str> = or.map(|x| &x[..2]);
-        assert_eq!(&*or, "el");
-    }
-
-    #[test]
-    fn map_chained_inference() {
-        let or = BoxRef::new(Box::new(example().1)).map(|x| &x[..5]).map(|x| &x[1..3]);
-        assert_eq!(&*or, "el");
-    }
-
-    #[test]
-    fn owner() {
-        let or: BoxRef<String> = Box::new(example().1).into();
-        let or = or.map(|x| &x[..5]);
-        assert_eq!(&*or, "hello");
-        assert_eq!(&**or.owner(), "hello world");
-    }
-
-    #[test]
-    fn into_inner() {
-        let or: BoxRef<String> = Box::new(example().1).into();
-        let or = or.map(|x| &x[..5]);
-        assert_eq!(&*or, "hello");
-        let s = *or.into_inner();
-        assert_eq!(&s, "hello world");
-    }
-
-    #[test]
-    fn fmt_debug() {
-        let or: BoxRef<String> = Box::new(example().1).into();
-        let or = or.map(|x| &x[..5]);
-        let s = format!("{:?}", or);
-        assert_eq!(&s, "OwningRef { owner: \"hello world\", reference: \"hello\" }");
-    }
-
-    #[test]
-    fn erased_owner() {
-        let o1: BoxRef<Example, str> = BoxRef::new(Box::new(example())).map(|x| &x.1[..]);
-
-        let o2: BoxRef<String, str> = BoxRef::new(Box::new(example().1)).map(|x| &x[..]);
-
-        let os: Vec<ErasedBoxRef<str>> = vec![o1.erase_owner(), o2.erase_owner()];
-        assert!(os.iter().all(|e| &e[..] == "hello world"));
-    }
-
-    #[test]
-    fn raii_locks() {
-        use super::super::{MutexGuardRef, RwLockReadGuardRef, RwLockWriteGuardRef};
-        use super::super::{RefMutRef, RefRef};
-        use std::cell::RefCell;
-        use std::sync::{Mutex, RwLock};
-
-        {
-            let a = RefCell::new(1);
-            let a = {
-                let a = RefRef::new(a.borrow());
-                assert_eq!(*a, 1);
-                a
-            };
-            assert_eq!(*a, 1);
-            drop(a);
-        }
-        {
-            let a = RefCell::new(1);
-            let a = {
-                let a = RefMutRef::new(a.borrow_mut());
-                assert_eq!(*a, 1);
-                a
-            };
-            assert_eq!(*a, 1);
-            drop(a);
-        }
-        {
-            let a = Mutex::new(1);
-            let a = {
-                let a = MutexGuardRef::new(a.lock().unwrap());
-                assert_eq!(*a, 1);
-                a
-            };
-            assert_eq!(*a, 1);
-            drop(a);
-        }
-        {
-            let a = RwLock::new(1);
-            let a = {
-                let a = RwLockReadGuardRef::new(a.read().unwrap());
-                assert_eq!(*a, 1);
-                a
-            };
-            assert_eq!(*a, 1);
-            drop(a);
-        }
-        {
-            let a = RwLock::new(1);
-            let a = {
-                let a = RwLockWriteGuardRef::new(a.write().unwrap());
-                assert_eq!(*a, 1);
-                a
-            };
-            assert_eq!(*a, 1);
-            drop(a);
-        }
-    }
-
-    #[test]
-    fn eq() {
-        let or1: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
-        let or2: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
-        assert_eq!(or1.eq(&or2), true);
-    }
-
-    #[test]
-    fn cmp() {
-        let or1: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
-        let or2: BoxRef<[u8]> = BoxRef::new(vec![4, 5, 6].into_boxed_slice());
-        assert_eq!(or1.cmp(&or2), Ordering::Less);
-    }
-
-    #[test]
-    fn partial_cmp() {
-        let or1: BoxRef<[u8]> = BoxRef::new(vec![4, 5, 6].into_boxed_slice());
-        let or2: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
-        assert_eq!(or1.partial_cmp(&or2), Some(Ordering::Greater));
-    }
-
-    #[test]
-    fn hash() {
-        let mut h1 = DefaultHasher::new();
-        let mut h2 = DefaultHasher::new();
-
-        let or1: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
-        let or2: BoxRef<[u8]> = BoxRef::new(vec![1, 2, 3].into_boxed_slice());
-
-        or1.hash(&mut h1);
-        or2.hash(&mut h2);
-
-        assert_eq!(h1.finish(), h2.finish());
-    }
-
-    #[test]
-    fn borrow() {
-        let mut hash = HashMap::new();
-        let key = RcRef::<String>::new(Rc::new("foo-bar".to_string())).map(|s| &s[..]);
-
-        hash.insert(key.clone().map(|s| &s[..3]), 42);
-        hash.insert(key.clone().map(|s| &s[4..]), 23);
-
-        assert_eq!(hash.get("foo"), Some(&42));
-        assert_eq!(hash.get("bar"), Some(&23));
-    }
-
-    #[test]
-    fn total_erase() {
-        let a: OwningRef<Vec<u8>, [u8]> = OwningRef::new(vec![]).map(|x| &x[..]);
-        let b: OwningRef<Box<[u8]>, [u8]> =
-            OwningRef::new(vec![].into_boxed_slice()).map(|x| &x[..]);
-
-        let c: OwningRef<Rc<Vec<u8>>, [u8]> = unsafe { a.map_owner(Rc::new) };
-        let d: OwningRef<Rc<Box<[u8]>>, [u8]> = unsafe { b.map_owner(Rc::new) };
-
-        let e: OwningRef<Rc<dyn Erased>, [u8]> = c.erase_owner();
-        let f: OwningRef<Rc<dyn Erased>, [u8]> = d.erase_owner();
-
-        let _g = e.clone();
-        let _h = f.clone();
-    }
-
-    #[test]
-    fn total_erase_box() {
-        let a: OwningRef<Vec<u8>, [u8]> = OwningRef::new(vec![]).map(|x| &x[..]);
-        let b: OwningRef<Box<[u8]>, [u8]> =
-            OwningRef::new(vec![].into_boxed_slice()).map(|x| &x[..]);
-
-        let c: OwningRef<Box<Vec<u8>>, [u8]> = a.map_owner_box();
-        let d: OwningRef<Box<Box<[u8]>>, [u8]> = b.map_owner_box();
-
-        let _e: OwningRef<Box<dyn Erased>, [u8]> = c.erase_owner();
-        let _f: OwningRef<Box<dyn Erased>, [u8]> = d.erase_owner();
-    }
-
-    #[test]
-    fn try_map1() {
-        use std::any::Any;
-
-        let x = Box::new(123_i32);
-        let y: Box<dyn Any> = x;
-
-        assert!(OwningRef::new(y).try_map(|x| x.downcast_ref::<i32>().ok_or(())).is_ok());
-    }
-
-    #[test]
-    fn try_map2() {
-        use std::any::Any;
-
-        let x = Box::new(123_i32);
-        let y: Box<dyn Any> = x;
-
-        assert!(!OwningRef::new(y).try_map(|x| x.downcast_ref::<i32>().ok_or(())).is_err());
-    }
-}
-
-mod owning_handle {
-    use super::super::OwningHandle;
-    use super::super::RcRef;
-    use std::cell::RefCell;
-    use std::rc::Rc;
-    use std::sync::Arc;
-    use std::sync::RwLock;
-
-    #[test]
-    fn owning_handle() {
-        use std::cell::RefCell;
-        let cell = Rc::new(RefCell::new(2));
-        let cell_ref = RcRef::new(cell);
-        let mut handle =
-            OwningHandle::new_with_fn(cell_ref, |x| unsafe { x.as_ref() }.unwrap().borrow_mut());
-        assert_eq!(*handle, 2);
-        *handle = 3;
-        assert_eq!(*handle, 3);
-    }
-
-    #[test]
-    fn try_owning_handle_ok() {
-        use std::cell::RefCell;
-        let cell = Rc::new(RefCell::new(2));
-        let cell_ref = RcRef::new(cell);
-        let mut handle = OwningHandle::try_new::<_, ()>(cell_ref, |x| {
-            Ok(unsafe { x.as_ref() }.unwrap().borrow_mut())
-        })
-        .unwrap();
-        assert_eq!(*handle, 2);
-        *handle = 3;
-        assert_eq!(*handle, 3);
-    }
-
-    #[test]
-    fn try_owning_handle_err() {
-        use std::cell::RefCell;
-        let cell = Rc::new(RefCell::new(2));
-        let cell_ref = RcRef::new(cell);
-        let handle = OwningHandle::try_new::<_, ()>(cell_ref, |x| {
-            if false {
-                return Ok(unsafe { x.as_ref() }.unwrap().borrow_mut());
-            }
-            Err(())
-        });
-        assert!(handle.is_err());
-    }
-
-    #[test]
-    fn nested() {
-        use std::cell::RefCell;
-        use std::sync::{Arc, RwLock};
-
-        let result = {
-            let complex = Rc::new(RefCell::new(Arc::new(RwLock::new("someString"))));
-            let curr = RcRef::new(complex);
-            let curr =
-                OwningHandle::new_with_fn(curr, |x| unsafe { x.as_ref() }.unwrap().borrow_mut());
-            let mut curr = OwningHandle::new_with_fn(curr, |x| {
-                unsafe { x.as_ref() }.unwrap().try_write().unwrap()
-            });
-            assert_eq!(*curr, "someString");
-            *curr = "someOtherString";
-            curr
-        };
-        assert_eq!(*result, "someOtherString");
-    }
-
-    #[test]
-    fn owning_handle_safe() {
-        use std::cell::RefCell;
-        let cell = Rc::new(RefCell::new(2));
-        let cell_ref = RcRef::new(cell);
-        let handle = OwningHandle::new(cell_ref);
-        assert_eq!(*handle, 2);
-    }
-
-    #[test]
-    fn owning_handle_mut_safe() {
-        use std::cell::RefCell;
-        let cell = Rc::new(RefCell::new(2));
-        let cell_ref = RcRef::new(cell);
-        let mut handle = OwningHandle::new_mut(cell_ref);
-        assert_eq!(*handle, 2);
-        *handle = 3;
-        assert_eq!(*handle, 3);
-    }
-
-    #[test]
-    fn owning_handle_safe_2() {
-        let result = {
-            let complex = Rc::new(RefCell::new(Arc::new(RwLock::new("someString"))));
-            let curr = RcRef::new(complex);
-            let curr =
-                OwningHandle::new_with_fn(curr, |x| unsafe { x.as_ref() }.unwrap().borrow_mut());
-            let mut curr = OwningHandle::new_with_fn(curr, |x| {
-                unsafe { x.as_ref() }.unwrap().try_write().unwrap()
-            });
-            assert_eq!(*curr, "someString");
-            *curr = "someOtherString";
-            curr
-        };
-        assert_eq!(*result, "someOtherString");
-    }
-}
-
-// FIXME: owning_ref is not sound under stacked borrows. Preferably, get rid of it.
-#[cfg(not(miri))]
-mod owning_ref_mut {
-    use super::super::BoxRef;
-    use super::super::{BoxRefMut, Erased, ErasedBoxRefMut, OwningRefMut};
-    use std::cmp::Ordering;
-    use std::collections::hash_map::DefaultHasher;
-    use std::collections::HashMap;
-    use std::hash::{Hash, Hasher};
-
-    #[derive(Debug, PartialEq)]
-    struct Example(u32, String, [u8; 3]);
-    fn example() -> Example {
-        Example(42, "hello world".to_string(), [1, 2, 3])
-    }
-
-    #[test]
-    fn new_deref() {
-        let or: OwningRefMut<Box<()>, ()> = OwningRefMut::new(Box::new(()));
-        assert_eq!(&*or, &());
-    }
-
-    #[test]
-    fn new_deref_mut() {
-        let mut or: OwningRefMut<Box<()>, ()> = OwningRefMut::new(Box::new(()));
-        assert_eq!(&mut *or, &mut ());
-    }
-
-    #[test]
-    fn mutate() {
-        let mut or: OwningRefMut<Box<usize>, usize> = OwningRefMut::new(Box::new(0));
-        assert_eq!(&*or, &0);
-        *or = 1;
-        assert_eq!(&*or, &1);
-    }
-
-    #[test]
-    fn into() {
-        let or: OwningRefMut<Box<()>, ()> = Box::new(()).into();
-        assert_eq!(&*or, &());
-    }
-
-    #[test]
-    fn map_offset_ref() {
-        let or: BoxRefMut<Example> = Box::new(example()).into();
-        let or: BoxRef<_, u32> = or.map(|x| &mut x.0);
-        assert_eq!(&*or, &42);
-
-        let or: BoxRefMut<Example> = Box::new(example()).into();
-        let or: BoxRef<_, u8> = or.map(|x| &mut x.2[1]);
-        assert_eq!(&*or, &2);
-    }
-
-    #[test]
-    fn map_heap_ref() {
-        let or: BoxRefMut<Example> = Box::new(example()).into();
-        let or: BoxRef<_, str> = or.map(|x| &mut x.1[..5]);
-        assert_eq!(&*or, "hello");
-    }
-
-    #[test]
-    fn map_static_ref() {
-        let or: BoxRefMut<()> = Box::new(()).into();
-        let or: BoxRef<_, str> = or.map(|_| "hello");
-        assert_eq!(&*or, "hello");
-    }
-
-    #[test]
-    fn map_mut_offset_ref() {
-        let or: BoxRefMut<Example> = Box::new(example()).into();
-        let or: BoxRefMut<_, u32> = or.map_mut(|x| &mut x.0);
-        assert_eq!(&*or, &42);
-
-        let or: BoxRefMut<Example> = Box::new(example()).into();
-        let or: BoxRefMut<_, u8> = or.map_mut(|x| &mut x.2[1]);
-        assert_eq!(&*or, &2);
-    }
-
-    #[test]
-    fn map_mut_heap_ref() {
-        let or: BoxRefMut<Example> = Box::new(example()).into();
-        let or: BoxRefMut<_, str> = or.map_mut(|x| &mut x.1[..5]);
-        assert_eq!(&*or, "hello");
-    }
-
-    #[test]
-    fn map_mut_static_ref() {
-        static mut MUT_S: [u8; 5] = *b"hello";
-
-        let mut_s: &'static mut [u8] = unsafe { &mut MUT_S };
-
-        let or: BoxRefMut<()> = Box::new(()).into();
-        let or: BoxRefMut<_, [u8]> = or.map_mut(move |_| mut_s);
-        assert_eq!(&*or, b"hello");
-    }
-
-    #[test]
-    fn map_mut_chained() {
-        let or: BoxRefMut<String> = Box::new(example().1).into();
-        let or: BoxRefMut<_, str> = or.map_mut(|x| &mut x[1..5]);
-        let or: BoxRefMut<_, str> = or.map_mut(|x| &mut x[..2]);
-        assert_eq!(&*or, "el");
-    }
-
-    #[test]
-    fn map_chained_inference() {
-        let or = BoxRefMut::new(Box::new(example().1))
-            .map_mut(|x| &mut x[..5])
-            .map_mut(|x| &mut x[1..3]);
-        assert_eq!(&*or, "el");
-    }
-
-    #[test]
-    fn try_map_mut() {
-        let or: BoxRefMut<String> = Box::new(example().1).into();
-        let or: Result<BoxRefMut<_, str>, ()> = or.try_map_mut(|x| Ok(&mut x[1..5]));
-        assert_eq!(&*or.unwrap(), "ello");
-
-        let or: BoxRefMut<String> = Box::new(example().1).into();
-        let or: Result<BoxRefMut<_, str>, ()> = or.try_map_mut(|_| Err(()));
-        assert!(or.is_err());
-    }
-
-    #[test]
-    fn owner() {
-        let or: BoxRefMut<String> = Box::new(example().1).into();
-        let or = or.map_mut(|x| &mut x[..5]);
-        assert_eq!(&*or, "hello");
-        assert_eq!(&**or.owner(), "hello world");
-    }
-
-    #[test]
-    fn into_inner() {
-        let or: BoxRefMut<String> = Box::new(example().1).into();
-        let or = or.map_mut(|x| &mut x[..5]);
-        assert_eq!(&*or, "hello");
-        let s = *or.into_inner();
-        assert_eq!(&s, "hello world");
-    }
-
-    #[test]
-    fn fmt_debug() {
-        let or: BoxRefMut<String> = Box::new(example().1).into();
-        let or = or.map_mut(|x| &mut x[..5]);
-        let s = format!("{:?}", or);
-        assert_eq!(&s, "OwningRefMut { owner: \"hello world\", reference: \"hello\" }");
-    }
-
-    #[test]
-    fn erased_owner() {
-        let o1: BoxRefMut<Example, str> =
-            BoxRefMut::new(Box::new(example())).map_mut(|x| &mut x.1[..]);
-
-        let o2: BoxRefMut<String, str> =
-            BoxRefMut::new(Box::new(example().1)).map_mut(|x| &mut x[..]);
-
-        let os: Vec<ErasedBoxRefMut<str>> = vec![o1.erase_owner(), o2.erase_owner()];
-        assert!(os.iter().all(|e| &e[..] == "hello world"));
-    }
-
-    #[test]
-    fn raii_locks() {
-        use super::super::RefMutRefMut;
-        use super::super::{MutexGuardRefMut, RwLockWriteGuardRefMut};
-        use std::cell::RefCell;
-        use std::sync::{Mutex, RwLock};
-
-        {
-            let a = RefCell::new(1);
-            let a = {
-                let a = RefMutRefMut::new(a.borrow_mut());
-                assert_eq!(*a, 1);
-                a
-            };
-            assert_eq!(*a, 1);
-            drop(a);
-        }
-        {
-            let a = Mutex::new(1);
-            let a = {
-                let a = MutexGuardRefMut::new(a.lock().unwrap());
-                assert_eq!(*a, 1);
-                a
-            };
-            assert_eq!(*a, 1);
-            drop(a);
-        }
-        {
-            let a = RwLock::new(1);
-            let a = {
-                let a = RwLockWriteGuardRefMut::new(a.write().unwrap());
-                assert_eq!(*a, 1);
-                a
-            };
-            assert_eq!(*a, 1);
-            drop(a);
-        }
-    }
-
-    #[test]
-    fn eq() {
-        let or1: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
-        let or2: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
-        assert_eq!(or1.eq(&or2), true);
-    }
-
-    #[test]
-    fn cmp() {
-        let or1: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
-        let or2: BoxRefMut<[u8]> = BoxRefMut::new(vec![4, 5, 6].into_boxed_slice());
-        assert_eq!(or1.cmp(&or2), Ordering::Less);
-    }
-
-    #[test]
-    fn partial_cmp() {
-        let or1: BoxRefMut<[u8]> = BoxRefMut::new(vec![4, 5, 6].into_boxed_slice());
-        let or2: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
-        assert_eq!(or1.partial_cmp(&or2), Some(Ordering::Greater));
-    }
-
-    #[test]
-    fn hash() {
-        let mut h1 = DefaultHasher::new();
-        let mut h2 = DefaultHasher::new();
-
-        let or1: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
-        let or2: BoxRefMut<[u8]> = BoxRefMut::new(vec![1, 2, 3].into_boxed_slice());
-
-        or1.hash(&mut h1);
-        or2.hash(&mut h2);
-
-        assert_eq!(h1.finish(), h2.finish());
-    }
-
-    #[test]
-    fn borrow() {
-        let mut hash = HashMap::new();
-        let key1 = BoxRefMut::<String>::new(Box::new("foo".to_string())).map(|s| &s[..]);
-        let key2 = BoxRefMut::<String>::new(Box::new("bar".to_string())).map(|s| &s[..]);
-
-        hash.insert(key1, 42);
-        hash.insert(key2, 23);
-
-        assert_eq!(hash.get("foo"), Some(&42));
-        assert_eq!(hash.get("bar"), Some(&23));
-    }
-
-    #[test]
-    fn total_erase() {
-        let a: OwningRefMut<Vec<u8>, [u8]> = OwningRefMut::new(vec![]).map_mut(|x| &mut x[..]);
-        let b: OwningRefMut<Box<[u8]>, [u8]> =
-            OwningRefMut::new(vec![].into_boxed_slice()).map_mut(|x| &mut x[..]);
-
-        let c: OwningRefMut<Box<Vec<u8>>, [u8]> = unsafe { a.map_owner(Box::new) };
-        let d: OwningRefMut<Box<Box<[u8]>>, [u8]> = unsafe { b.map_owner(Box::new) };
-
-        let _e: OwningRefMut<Box<dyn Erased>, [u8]> = c.erase_owner();
-        let _f: OwningRefMut<Box<dyn Erased>, [u8]> = d.erase_owner();
-    }
-
-    #[test]
-    fn total_erase_box() {
-        let a: OwningRefMut<Vec<u8>, [u8]> = OwningRefMut::new(vec![]).map_mut(|x| &mut x[..]);
-        let b: OwningRefMut<Box<[u8]>, [u8]> =
-            OwningRefMut::new(vec![].into_boxed_slice()).map_mut(|x| &mut x[..]);
-
-        let c: OwningRefMut<Box<Vec<u8>>, [u8]> = a.map_owner_box();
-        let d: OwningRefMut<Box<Box<[u8]>>, [u8]> = b.map_owner_box();
-
-        let _e: OwningRefMut<Box<dyn Erased>, [u8]> = c.erase_owner();
-        let _f: OwningRefMut<Box<dyn Erased>, [u8]> = d.erase_owner();
-    }
-
-    #[test]
-    fn try_map1() {
-        use std::any::Any;
-
-        let x = Box::new(123_i32);
-        let y: Box<dyn Any> = x;
-
-        assert!(OwningRefMut::new(y).try_map_mut(|x| x.downcast_mut::<i32>().ok_or(())).is_ok());
-    }
-
-    #[test]
-    fn try_map2() {
-        use std::any::Any;
-
-        let x = Box::new(123_i32);
-        let y: Box<dyn Any> = x;
-
-        assert!(!OwningRefMut::new(y).try_map_mut(|x| x.downcast_mut::<i32>().ok_or(())).is_err());
-    }
-
-    #[test]
-    fn try_map3() {
-        use std::any::Any;
-
-        let x = Box::new(123_i32);
-        let y: Box<dyn Any> = x;
-
-        assert!(OwningRefMut::new(y).try_map(|x| x.downcast_ref::<i32>().ok_or(())).is_ok());
-    }
-
-    #[test]
-    fn try_map4() {
-        use std::any::Any;
-
-        let x = Box::new(123_i32);
-        let y: Box<dyn Any> = x;
-
-        assert!(!OwningRefMut::new(y).try_map(|x| x.downcast_ref::<i32>().ok_or(())).is_err());
-    }
-
-    #[test]
-    fn into_owning_ref() {
-        use super::super::BoxRef;
-
-        let or: BoxRefMut<()> = Box::new(()).into();
-        let or: BoxRef<()> = or.into();
-        assert_eq!(&*or, &());
-    }
-
-    struct Foo {
-        u: u32,
-    }
-    struct Bar {
-        f: Foo,
-    }
-
-    #[test]
-    fn ref_mut() {
-        use std::cell::RefCell;
-
-        let a = RefCell::new(Bar { f: Foo { u: 42 } });
-        let mut b = OwningRefMut::new(a.borrow_mut());
-        assert_eq!(b.f.u, 42);
-        b.f.u = 43;
-        let mut c = b.map_mut(|x| &mut x.f);
-        assert_eq!(c.u, 43);
-        c.u = 44;
-        let mut d = c.map_mut(|x| &mut x.u);
-        assert_eq!(*d, 44);
-        *d = 45;
-        assert_eq!(*d, 45);
-    }
-}
diff --git a/compiler/rustc_data_structures/src/profiling.rs b/compiler/rustc_data_structures/src/profiling.rs
index 58a0609e296..1ed584eafad 100644
--- a/compiler/rustc_data_structures/src/profiling.rs
+++ b/compiler/rustc_data_structures/src/profiling.rs
@@ -778,7 +778,7 @@ pub fn print_time_passes_entry(
                 "rss_start": start_rss,
                 "rss_end": end_rss,
             });
-            eprintln!("time: {}", json.to_string());
+            eprintln!("time: {json}");
             return;
         }
         TimePassesFormat::Text => (),
diff --git a/compiler/rustc_data_structures/src/sharded.rs b/compiler/rustc_data_structures/src/sharded.rs
index f88c055a9b5..bd7a86f6780 100644
--- a/compiler/rustc_data_structures/src/sharded.rs
+++ b/compiler/rustc_data_structures/src/sharded.rs
@@ -140,6 +140,7 @@ pub fn make_hash<K: Hash + ?Sized>(val: &K) -> u64 {
 /// `hash` can be computed with any hasher, so long as that hasher is used
 /// consistently for each `Sharded` instance.
 #[inline]
+#[allow(clippy::modulo_one)]
 pub fn get_shard_index_by_hash(hash: u64) -> usize {
     let hash_len = mem::size_of::<usize>();
     // Ignore the top 7 bits as hashbrown uses these and get the next SHARD_BITS highest bits.
diff --git a/compiler/rustc_data_structures/src/sip128.rs b/compiler/rustc_data_structures/src/sip128.rs
index 90793a97ed0..d849fe0373f 100644
--- a/compiler/rustc_data_structures/src/sip128.rs
+++ b/compiler/rustc_data_structures/src/sip128.rs
@@ -247,7 +247,7 @@ impl SipHasher128 {
         for i in 0..BUFFER_CAPACITY {
             let elem = self.buf.get_unchecked(i).assume_init().to_le();
             self.state.v3 ^= elem;
-            Sip24Rounds::c_rounds(&mut self.state);
+            Sip13Rounds::c_rounds(&mut self.state);
             self.state.v0 ^= elem;
         }
 
@@ -327,7 +327,7 @@ impl SipHasher128 {
         for i in 0..last {
             let elem = self.buf.get_unchecked(i).assume_init().to_le();
             self.state.v3 ^= elem;
-            Sip24Rounds::c_rounds(&mut self.state);
+            Sip13Rounds::c_rounds(&mut self.state);
             self.state.v0 ^= elem;
         }
 
@@ -340,7 +340,7 @@ impl SipHasher128 {
         for _ in 0..elems_left {
             let elem = (msg.as_ptr().add(processed) as *const u64).read_unaligned().to_le();
             self.state.v3 ^= elem;
-            Sip24Rounds::c_rounds(&mut self.state);
+            Sip13Rounds::c_rounds(&mut self.state);
             self.state.v0 ^= elem;
             processed += ELEM_SIZE;
         }
@@ -368,7 +368,7 @@ impl SipHasher128 {
         for i in 0..last {
             let elem = unsafe { self.buf.get_unchecked(i).assume_init().to_le() };
             state.v3 ^= elem;
-            Sip24Rounds::c_rounds(&mut state);
+            Sip13Rounds::c_rounds(&mut state);
             state.v0 ^= elem;
         }
 
@@ -392,15 +392,15 @@ impl SipHasher128 {
         let b: u64 = ((length as u64 & 0xff) << 56) | elem;
 
         state.v3 ^= b;
-        Sip24Rounds::c_rounds(&mut state);
+        Sip13Rounds::c_rounds(&mut state);
         state.v0 ^= b;
 
         state.v2 ^= 0xee;
-        Sip24Rounds::d_rounds(&mut state);
+        Sip13Rounds::d_rounds(&mut state);
         let _0 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
 
         state.v1 ^= 0xdd;
-        Sip24Rounds::d_rounds(&mut state);
+        Sip13Rounds::d_rounds(&mut state);
         let _1 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
 
         (_0, _1)
@@ -477,13 +477,12 @@ impl Hasher for SipHasher128 {
 }
 
 #[derive(Debug, Clone, Default)]
-struct Sip24Rounds;
+struct Sip13Rounds;
 
-impl Sip24Rounds {
+impl Sip13Rounds {
     #[inline]
     fn c_rounds(state: &mut State) {
         compress!(state);
-        compress!(state);
     }
 
     #[inline]
@@ -491,6 +490,5 @@ impl Sip24Rounds {
         compress!(state);
         compress!(state);
         compress!(state);
-        compress!(state);
     }
 }
diff --git a/compiler/rustc_data_structures/src/sip128/tests.rs b/compiler/rustc_data_structures/src/sip128/tests.rs
index 5fe967c4158..cc6d3b0f471 100644
--- a/compiler/rustc_data_structures/src/sip128/tests.rs
+++ b/compiler/rustc_data_structures/src/sip128/tests.rs
@@ -22,269 +22,76 @@ fn hash_with<T: Hash>(mut st: SipHasher128, x: &T) -> (u64, u64) {
 fn hash<T: Hash>(x: &T) -> (u64, u64) {
     hash_with(SipHasher128::new_with_keys(0, 0), x)
 }
-
+#[rustfmt::skip]
 const TEST_VECTOR: [[u8; 16]; 64] = [
-    [
-        0xa3, 0x81, 0x7f, 0x04, 0xba, 0x25, 0xa8, 0xe6, 0x6d, 0xf6, 0x72, 0x14, 0xc7, 0x55, 0x02,
-        0x93,
-    ],
-    [
-        0xda, 0x87, 0xc1, 0xd8, 0x6b, 0x99, 0xaf, 0x44, 0x34, 0x76, 0x59, 0x11, 0x9b, 0x22, 0xfc,
-        0x45,
-    ],
-    [
-        0x81, 0x77, 0x22, 0x8d, 0xa4, 0xa4, 0x5d, 0xc7, 0xfc, 0xa3, 0x8b, 0xde, 0xf6, 0x0a, 0xff,
-        0xe4,
-    ],
-    [
-        0x9c, 0x70, 0xb6, 0x0c, 0x52, 0x67, 0xa9, 0x4e, 0x5f, 0x33, 0xb6, 0xb0, 0x29, 0x85, 0xed,
-        0x51,
-    ],
-    [
-        0xf8, 0x81, 0x64, 0xc1, 0x2d, 0x9c, 0x8f, 0xaf, 0x7d, 0x0f, 0x6e, 0x7c, 0x7b, 0xcd, 0x55,
-        0x79,
-    ],
-    [
-        0x13, 0x68, 0x87, 0x59, 0x80, 0x77, 0x6f, 0x88, 0x54, 0x52, 0x7a, 0x07, 0x69, 0x0e, 0x96,
-        0x27,
-    ],
-    [
-        0x14, 0xee, 0xca, 0x33, 0x8b, 0x20, 0x86, 0x13, 0x48, 0x5e, 0xa0, 0x30, 0x8f, 0xd7, 0xa1,
-        0x5e,
-    ],
-    [
-        0xa1, 0xf1, 0xeb, 0xbe, 0xd8, 0xdb, 0xc1, 0x53, 0xc0, 0xb8, 0x4a, 0xa6, 0x1f, 0xf0, 0x82,
-        0x39,
-    ],
-    [
-        0x3b, 0x62, 0xa9, 0xba, 0x62, 0x58, 0xf5, 0x61, 0x0f, 0x83, 0xe2, 0x64, 0xf3, 0x14, 0x97,
-        0xb4,
-    ],
-    [
-        0x26, 0x44, 0x99, 0x06, 0x0a, 0xd9, 0xba, 0xab, 0xc4, 0x7f, 0x8b, 0x02, 0xbb, 0x6d, 0x71,
-        0xed,
-    ],
-    [
-        0x00, 0x11, 0x0d, 0xc3, 0x78, 0x14, 0x69, 0x56, 0xc9, 0x54, 0x47, 0xd3, 0xf3, 0xd0, 0xfb,
-        0xba,
-    ],
-    [
-        0x01, 0x51, 0xc5, 0x68, 0x38, 0x6b, 0x66, 0x77, 0xa2, 0xb4, 0xdc, 0x6f, 0x81, 0xe5, 0xdc,
-        0x18,
-    ],
-    [
-        0xd6, 0x26, 0xb2, 0x66, 0x90, 0x5e, 0xf3, 0x58, 0x82, 0x63, 0x4d, 0xf6, 0x85, 0x32, 0xc1,
-        0x25,
-    ],
-    [
-        0x98, 0x69, 0xe2, 0x47, 0xe9, 0xc0, 0x8b, 0x10, 0xd0, 0x29, 0x93, 0x4f, 0xc4, 0xb9, 0x52,
-        0xf7,
-    ],
-    [
-        0x31, 0xfc, 0xef, 0xac, 0x66, 0xd7, 0xde, 0x9c, 0x7e, 0xc7, 0x48, 0x5f, 0xe4, 0x49, 0x49,
-        0x02,
-    ],
-    [
-        0x54, 0x93, 0xe9, 0x99, 0x33, 0xb0, 0xa8, 0x11, 0x7e, 0x08, 0xec, 0x0f, 0x97, 0xcf, 0xc3,
-        0xd9,
-    ],
-    [
-        0x6e, 0xe2, 0xa4, 0xca, 0x67, 0xb0, 0x54, 0xbb, 0xfd, 0x33, 0x15, 0xbf, 0x85, 0x23, 0x05,
-        0x77,
-    ],
-    [
-        0x47, 0x3d, 0x06, 0xe8, 0x73, 0x8d, 0xb8, 0x98, 0x54, 0xc0, 0x66, 0xc4, 0x7a, 0xe4, 0x77,
-        0x40,
-    ],
-    [
-        0xa4, 0x26, 0xe5, 0xe4, 0x23, 0xbf, 0x48, 0x85, 0x29, 0x4d, 0xa4, 0x81, 0xfe, 0xae, 0xf7,
-        0x23,
-    ],
-    [
-        0x78, 0x01, 0x77, 0x31, 0xcf, 0x65, 0xfa, 0xb0, 0x74, 0xd5, 0x20, 0x89, 0x52, 0x51, 0x2e,
-        0xb1,
-    ],
-    [
-        0x9e, 0x25, 0xfc, 0x83, 0x3f, 0x22, 0x90, 0x73, 0x3e, 0x93, 0x44, 0xa5, 0xe8, 0x38, 0x39,
-        0xeb,
-    ],
-    [
-        0x56, 0x8e, 0x49, 0x5a, 0xbe, 0x52, 0x5a, 0x21, 0x8a, 0x22, 0x14, 0xcd, 0x3e, 0x07, 0x1d,
-        0x12,
-    ],
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+    [0xad, 0xe8, 0x3c, 0xf7, 0xe7, 0xf3, 0x84, 0x7b, 0x36, 0xfa, 0x4b, 0x54, 0xb0, 0x0d, 0xce, 0x61],
+    [0x06, 0x10, 0xc5, 0xf2, 0xee, 0x57, 0x1c, 0x8a, 0xc8, 0x0c, 0xbf, 0xe5, 0x38, 0xbd, 0xf1, 0xc7],
+    [0x27, 0x1d, 0x5d, 0x00, 0xfb, 0xdb, 0x5d, 0x15, 0x5d, 0x9d, 0xce, 0xa9, 0x7c, 0xb4, 0x02, 0x18],
+    [0x4c, 0x58, 0x00, 0xe3, 0x4e, 0xfe, 0x42, 0x6f, 0x07, 0x9f, 0x6b, 0x0a, 0xa7, 0x52, 0x60, 0xad],
 ];
 
-// Test vector from reference implementation
 #[test]
-fn test_siphash_2_4_test_vector() {
+fn test_siphash_1_3_test_vector() {
     let k0 = 0x_07_06_05_04_03_02_01_00;
     let k1 = 0x_0f_0e_0d_0c_0b_0a_09_08;
 
diff --git a/compiler/rustc_data_structures/src/stable_hasher.rs b/compiler/rustc_data_structures/src/stable_hasher.rs
index de9842156d6..3ed1de1bc3c 100644
--- a/compiler/rustc_data_structures/src/stable_hasher.rs
+++ b/compiler/rustc_data_structures/src/stable_hasher.rs
@@ -312,14 +312,14 @@ impl<CTX> HashStable<CTX> for ::std::num::NonZeroUsize {
 
 impl<CTX> HashStable<CTX> for f32 {
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
-        let val: u32 = unsafe { ::std::mem::transmute(*self) };
+        let val: u32 = self.to_bits();
         val.hash_stable(ctx, hasher);
     }
 }
 
 impl<CTX> HashStable<CTX> for f64 {
     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
-        let val: u64 = unsafe { ::std::mem::transmute(*self) };
+        let val: u64 = self.to_bits();
         val.hash_stable(ctx, hasher);
     }
 }
diff --git a/compiler/rustc_data_structures/src/stable_hasher/tests.rs b/compiler/rustc_data_structures/src/stable_hasher/tests.rs
index 724be5888dd..a98b1bc3626 100644
--- a/compiler/rustc_data_structures/src/stable_hasher/tests.rs
+++ b/compiler/rustc_data_structures/src/stable_hasher/tests.rs
@@ -39,7 +39,7 @@ fn test_hash_integers() {
     test_isize.hash(&mut h);
 
     // This depends on the hashing algorithm. See note at top of file.
-    let expected = (1784307454142909076, 11471672289340283879);
+    let expected = (13997337031081104755, 6178945012502239489);
 
     assert_eq!(h.finalize(), expected);
 }
@@ -53,7 +53,7 @@ fn test_hash_usize() {
     test_usize.hash(&mut h);
 
     // This depends on the hashing algorithm. See note at top of file.
-    let expected = (5798740672699530587, 11186240177685111648);
+    let expected = (12037165114281468837, 3094087741167521712);
 
     assert_eq!(h.finalize(), expected);
 }
@@ -67,7 +67,7 @@ fn test_hash_isize() {
     test_isize.hash(&mut h);
 
     // This depends on the hashing algorithm. See note at top of file.
-    let expected = (2789913510339652884, 674280939192711005);
+    let expected = (3979067582695659080, 2322428596355037273);
 
     assert_eq!(h.finalize(), expected);
 }
diff --git a/compiler/rustc_data_structures/src/stack.rs b/compiler/rustc_data_structures/src/stack.rs
index 3bdd6751232..7ff1339c5ab 100644
--- a/compiler/rustc_data_structures/src/stack.rs
+++ b/compiler/rustc_data_structures/src/stack.rs
@@ -5,7 +5,7 @@ const RED_ZONE: usize = 100 * 1024; // 100k
 
 // Only the first stack that is pushed, grows exponentially (2^n * STACK_PER_RECURSION) from then
 // on. This flag has performance relevant characteristics. Don't set it too high.
-const STACK_PER_RECURSION: usize = 1 * 1024 * 1024; // 1MB
+const STACK_PER_RECURSION: usize = 1024 * 1024; // 1MB
 
 /// Grows the stack on demand to prevent stack overflow. Call this in strategic locations
 /// to "break up" recursive calls. E.g. almost any call to `visit_expr` or equivalent can benefit
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 4e2126fff7b..ef1da85198f 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -7,9 +7,6 @@
 //! while the serial versions degenerate straightforwardly to serial execution.
 //! The operations include `join`, `parallel`, `par_iter`, and `par_for_each`.
 //!
-//! `rustc_erase_owner!` erases an `OwningRef` owner into `Erased` for the
-//! serial version and `Erased + Send + Sync` for the parallel version.
-//!
 //! Types
 //! -----
 //! The parallel versions of types provide various kinds of synchronization,
@@ -42,7 +39,7 @@
 //!
 //! [^2] `MTLockRef` is a typedef.
 
-use crate::owning_ref::{Erased, OwningRef};
+use crate::owned_slice::OwnedSlice;
 use std::collections::HashMap;
 use std::hash::{BuildHasher, Hash};
 use std::ops::{Deref, DerefMut};
@@ -51,24 +48,17 @@ use std::panic::{catch_unwind, resume_unwind, AssertUnwindSafe};
 pub use std::sync::atomic::Ordering;
 pub use std::sync::atomic::Ordering::SeqCst;
 
-pub use vec::AppendOnlyVec;
+pub use vec::{AppendOnlyIndexVec, AppendOnlyVec};
 
 mod vec;
 
 cfg_if! {
     if #[cfg(not(parallel_compiler))] {
-        pub auto trait Send {}
-        pub auto trait Sync {}
-
-        impl<T> Send for T {}
-        impl<T> Sync for T {}
+        pub unsafe auto trait Send {}
+        pub unsafe auto trait Sync {}
 
-        #[macro_export]
-        macro_rules! rustc_erase_owner {
-            ($v:expr) => {
-                $v.erase_owner()
-            }
-        }
+        unsafe impl<T> Send for T {}
+        unsafe impl<T> Sync for T {}
 
         use std::ops::Add;
 
@@ -107,6 +97,14 @@ cfg_if! {
             }
         }
 
+        impl Atomic<bool> {
+            pub fn fetch_or(&self, val: bool, _: Ordering) -> bool {
+                let result = self.0.get() | val;
+                self.0.set(val);
+                result
+            }
+        }
+
         impl<T: Copy + PartialEq> Atomic<T> {
             #[inline]
             pub fn compare_exchange(&self,
@@ -189,7 +187,7 @@ cfg_if! {
             }
         }
 
-        pub type MetadataRef = OwningRef<Box<dyn Erased>, [u8]>;
+        pub type MetadataRef = OwnedSlice;
 
         pub use std::rc::Rc as Lrc;
         pub use std::rc::Weak as Weak;
@@ -372,20 +370,11 @@ cfg_if! {
             });
         }
 
-        pub type MetadataRef = OwningRef<Box<dyn Erased + Send + Sync>, [u8]>;
+        pub type MetadataRef = OwnedSlice;
 
         /// This makes locks panic if they are already held.
         /// It is only useful when you are running in a single thread
         const ERROR_CHECKING: bool = false;
-
-        #[macro_export]
-        macro_rules! rustc_erase_owner {
-            ($v:expr) => {{
-                let v = $v;
-                ::rustc_data_structures::sync::assert_send_val(&v);
-                v.erase_send_sync_owner()
-            }}
-        }
     }
 }
 
@@ -481,14 +470,6 @@ impl<T: Default> Default for Lock<T> {
     }
 }
 
-// FIXME: Probably a bad idea
-impl<T: Clone> Clone for Lock<T> {
-    #[inline]
-    fn clone(&self) -> Self {
-        Lock::new(self.borrow().clone())
-    }
-}
-
 #[derive(Debug, Default)]
 pub struct RwLock<T>(InnerRwLock<T>);
 
diff --git a/compiler/rustc_data_structures/src/sync/vec.rs b/compiler/rustc_data_structures/src/sync/vec.rs
index cbea4f05999..1783b4b3572 100644
--- a/compiler/rustc_data_structures/src/sync/vec.rs
+++ b/compiler/rustc_data_structures/src/sync/vec.rs
@@ -2,7 +2,8 @@ use std::marker::PhantomData;
 
 use rustc_index::vec::Idx;
 
-pub struct AppendOnlyVec<I: Idx, T: Copy> {
+#[derive(Default)]
+pub struct AppendOnlyIndexVec<I: Idx, T: Copy> {
     #[cfg(not(parallel_compiler))]
     vec: elsa::vec::FrozenVec<T>,
     #[cfg(parallel_compiler)]
@@ -10,7 +11,7 @@ pub struct AppendOnlyVec<I: Idx, T: Copy> {
     _marker: PhantomData<fn(&I)>,
 }
 
-impl<I: Idx, T: Copy> AppendOnlyVec<I, T> {
+impl<I: Idx, T: Copy> AppendOnlyIndexVec<I, T> {
     pub fn new() -> Self {
         Self {
             #[cfg(not(parallel_compiler))]
@@ -39,3 +40,66 @@ impl<I: Idx, T: Copy> AppendOnlyVec<I, T> {
         return self.vec.get(i);
     }
 }
+
+#[derive(Default)]
+pub struct AppendOnlyVec<T: Copy> {
+    #[cfg(not(parallel_compiler))]
+    vec: elsa::vec::FrozenVec<T>,
+    #[cfg(parallel_compiler)]
+    vec: elsa::sync::LockFreeFrozenVec<T>,
+}
+
+impl<T: Copy> AppendOnlyVec<T> {
+    pub fn new() -> Self {
+        Self {
+            #[cfg(not(parallel_compiler))]
+            vec: elsa::vec::FrozenVec::new(),
+            #[cfg(parallel_compiler)]
+            vec: elsa::sync::LockFreeFrozenVec::new(),
+        }
+    }
+
+    pub fn push(&self, val: T) -> usize {
+        #[cfg(not(parallel_compiler))]
+        let i = self.vec.len();
+        #[cfg(not(parallel_compiler))]
+        self.vec.push(val);
+        #[cfg(parallel_compiler)]
+        let i = self.vec.push(val);
+        i
+    }
+
+    pub fn get(&self, i: usize) -> Option<T> {
+        #[cfg(not(parallel_compiler))]
+        return self.vec.get_copy(i);
+        #[cfg(parallel_compiler)]
+        return self.vec.get(i);
+    }
+
+    pub fn iter_enumerated(&self) -> impl Iterator<Item = (usize, T)> + '_ {
+        (0..)
+            .map(|i| (i, self.get(i)))
+            .take_while(|(_, o)| o.is_some())
+            .filter_map(|(i, o)| Some((i, o?)))
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = T> + '_ {
+        (0..).map(|i| self.get(i)).take_while(|o| o.is_some()).flatten()
+    }
+}
+
+impl<T: Copy + PartialEq> AppendOnlyVec<T> {
+    pub fn contains(&self, val: T) -> bool {
+        self.iter_enumerated().any(|(_, v)| v == val)
+    }
+}
+
+impl<A: Copy> FromIterator<A> for AppendOnlyVec<A> {
+    fn from_iter<T: IntoIterator<Item = A>>(iter: T) -> Self {
+        let this = Self::new();
+        for val in iter {
+            this.push(val);
+        }
+        this
+    }
+}
diff --git a/compiler/rustc_data_structures/src/unord.rs b/compiler/rustc_data_structures/src/unord.rs
index 5c2435a0122..6c8d5414631 100644
--- a/compiler/rustc_data_structures/src/unord.rs
+++ b/compiler/rustc_data_structures/src/unord.rs
@@ -224,7 +224,7 @@ impl<V: Eq + Hash> UnordSet<V> {
     }
 
     #[inline]
-    pub fn items<'a>(&'a self) -> UnordItems<&'a V, impl Iterator<Item = &'a V>> {
+    pub fn items(&self) -> UnordItems<&V, impl Iterator<Item = &V>> {
         UnordItems(self.inner.iter())
     }
 
@@ -415,7 +415,7 @@ impl<K: Eq + Hash, V> UnordMap<K, V> {
     }
 
     #[inline]
-    pub fn items<'a>(&'a self) -> UnordItems<(&'a K, &'a V), impl Iterator<Item = (&'a K, &'a V)>> {
+    pub fn items(&self) -> UnordItems<(&K, &V), impl Iterator<Item = (&K, &V)>> {
         UnordItems(self.inner.iter())
     }