Make the stdlib largely conform to strict provenance.

Some things like the unwinders and system APIs are not fully conformant,
this only covers a lot of low-hanging fruit.

30 files changed, 100 insertions, 81 deletions

diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 0a180b83355..7e90d77b8f2 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -158,6 +158,7 @@
 #![feature(rustc_allow_const_fn_unstable)]
 #![feature(rustc_attrs)]
 #![feature(staged_api)]
+#![feature(strict_provenance)]
 #![cfg_attr(test, feature(test))]
 #![feature(unboxed_closures)]
 #![feature(unsized_fn_params)]
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index 3ddc9acb2e7..0b57c36247e 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -2115,13 +2115,12 @@ impl<T> Weak<T> {
     #[rustc_const_unstable(feature = "const_weak_new", issue = "95091", reason = "recently added")]
     #[must_use]
     pub const fn new() -> Weak<T> {
-        Weak { ptr: unsafe { NonNull::new_unchecked(usize::MAX as *mut RcBox<T>) } }
+        Weak { ptr: unsafe { NonNull::new_unchecked(ptr::invalid_mut::<RcBox<T>>(usize::MAX)) } }
     }
 }
 
 pub(crate) fn is_dangling<T: ?Sized>(ptr: *mut T) -> bool {
-    let address = ptr as *mut () as usize;
-    address == usize::MAX
+    (ptr as *mut ()).addr() == usize::MAX
 }
 
 /// Helper type to allow accessing the reference counts without
diff --git a/library/alloc/src/slice.rs b/library/alloc/src/slice.rs
index f52871c73d9..7c892f03bfb 100644
--- a/library/alloc/src/slice.rs
+++ b/library/alloc/src/slice.rs
@@ -1044,7 +1044,7 @@ where
     impl<T> Drop for MergeHole<T> {
         fn drop(&mut self) {
             // `T` is not a zero-sized type, so it's okay to divide by its size.
-            let len = (self.end as usize - self.start as usize) / mem::size_of::<T>();
+            let len = (self.end.addr() - self.start.addr()) / mem::size_of::<T>();
             unsafe {
                 ptr::copy_nonoverlapping(self.start, self.dest, len);
             }
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index e2b9890850b..f8b4d46ac10 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -1746,7 +1746,7 @@ impl<T> Weak<T> {
     #[rustc_const_unstable(feature = "const_weak_new", issue = "95091", reason = "recently added")]
     #[must_use]
     pub const fn new() -> Weak<T> {
-        Weak { ptr: unsafe { NonNull::new_unchecked(usize::MAX as *mut ArcInner<T>) } }
+        Weak { ptr: unsafe { NonNull::new_unchecked(ptr::invalid_mut::<ArcInner<T>>(usize::MAX)) } }
     }
 }
 
diff --git a/library/alloc/src/vec/into_iter.rs b/library/alloc/src/vec/into_iter.rs
index f17b8d71b3a..cc6dfb0e330 100644
--- a/library/alloc/src/vec/into_iter.rs
+++ b/library/alloc/src/vec/into_iter.rs
@@ -159,7 +159,7 @@ impl<T, A: Allocator> Iterator for IntoIter<T, A> {
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
         let exact = if mem::size_of::<T>() == 0 {
-            (self.end as usize).wrapping_sub(self.ptr as usize)
+            self.end.addr().wrapping_sub(self.ptr.addr())
         } else {
             unsafe { self.end.offset_from(self.ptr) as usize }
         };
diff --git a/library/core/src/alloc/layout.rs b/library/core/src/alloc/layout.rs
index ea639268652..0639d6eed62 100644
--- a/library/core/src/alloc/layout.rs
+++ b/library/core/src/alloc/layout.rs
@@ -194,7 +194,7 @@ impl Layout {
     #[inline]
     pub const fn dangling(&self) -> NonNull<u8> {
         // SAFETY: align is guaranteed to be non-zero
-        unsafe { NonNull::new_unchecked(self.align() as *mut u8) }
+        unsafe { NonNull::new_unchecked(crate::ptr::invalid_mut::<u8>(self.align())) }
     }
 
     /// Creates a layout describing the record that can hold a value
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 84cf1753f86..0e2e869a920 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -352,7 +352,11 @@ impl<'a> ArgumentV1<'a> {
     }
 
     fn as_usize(&self) -> Option<usize> {
-        if self.formatter as usize == USIZE_MARKER as usize {
+        // We are type punning a bit here: USIZE_MARKER only takes an &usize but
+        // formatter takes an &Opaque. Rust understandably doesn't think we should compare
+        // the function pointers if they don't have the same signature, so we cast to
+        // pointers to convince it that we know what we're doing.
+        if self.formatter as *mut u8 == USIZE_MARKER as *mut u8 {
             // SAFETY: The `formatter` field is only set to USIZE_MARKER if
             // the value is a usize, so this is safe
             Some(unsafe { *(self.value as *const _ as *const usize) })
@@ -2246,7 +2250,7 @@ impl<T: ?Sized> Pointer for *const T {
             }
             f.flags |= 1 << (FlagV1::Alternate as u32);
 
-            let ret = LowerHex::fmt(&(ptr as usize), f);
+            let ret = LowerHex::fmt(&(ptr.addr()), f);
 
             f.width = old_width;
             f.flags = old_flags;
diff --git a/library/core/src/hash/mod.rs b/library/core/src/hash/mod.rs
index 53de8b42c05..45c9df0c930 100644
--- a/library/core/src/hash/mod.rs
+++ b/library/core/src/hash/mod.rs
@@ -793,7 +793,7 @@ mod impls {
         #[inline]
         fn hash<H: Hasher>(&self, state: &mut H) {
             let (address, metadata) = self.to_raw_parts();
-            state.write_usize(address as usize);
+            state.write_usize(address.addr());
             metadata.hash(state);
         }
     }
@@ -803,7 +803,7 @@ mod impls {
         #[inline]
         fn hash<H: Hasher>(&self, state: &mut H) {
             let (address, metadata) = self.to_raw_parts();
-            state.write_usize(address as usize);
+            state.write_usize(address.addr());
             metadata.hash(state);
         }
     }
diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index 129402ad23a..8ad4317c145 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs
@@ -1972,15 +1972,15 @@ extern "rust-intrinsic" {
 /// Checks whether `ptr` is properly aligned with respect to
 /// `align_of::<T>()`.
 pub(crate) fn is_aligned_and_not_null<T>(ptr: *const T) -> bool {
-    !ptr.is_null() && ptr as usize % mem::align_of::<T>() == 0
+    !ptr.is_null() && ptr.addr() % mem::align_of::<T>() == 0
 }
 
 /// Checks whether the regions of memory starting at `src` and `dst` of size
 /// `count * size_of::<T>()` do *not* overlap.
 #[cfg(debug_assertions)]
 pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -> bool {
-    let src_usize = src as usize;
-    let dst_usize = dst as usize;
+    let src_usize = src.addr();
+    let dst_usize = dst.addr();
     let size = mem::size_of::<T>().checked_mul(count).unwrap();
     let diff = if src_usize > dst_usize { src_usize - dst_usize } else { dst_usize - src_usize };
     // If the absolute distance between the ptrs is at least as big as the size of the buffer,
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index a698aec51ca..c1b19895f00 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -90,7 +90,7 @@ impl<T: Sized> NonNull<T> {
         // to a *mut T. Therefore, `ptr` is not null and the conditions for
         // calling new_unchecked() are respected.
         unsafe {
-            let ptr = mem::align_of::<T>() as *mut T;
+            let ptr = crate::ptr::invalid_mut::<T>(mem::align_of::<T>());
             NonNull::new_unchecked(ptr)
         }
     }
@@ -469,7 +469,7 @@ impl<T> NonNull<[T]> {
     /// use std::ptr::NonNull;
     ///
     /// let slice: NonNull<[i8]> = NonNull::slice_from_raw_parts(NonNull::dangling(), 3);
-    /// assert_eq!(slice.as_non_null_ptr(), NonNull::new(1 as *mut i8).unwrap());
+    /// assert_eq!(slice.as_non_null_ptr(), NonNull::<i8>::dangling());
     /// ```
     #[inline]
     #[must_use]
@@ -489,7 +489,7 @@ impl<T> NonNull<[T]> {
     /// use std::ptr::NonNull;
     ///
     /// let slice: NonNull<[i8]> = NonNull::slice_from_raw_parts(NonNull::dangling(), 3);
-    /// assert_eq!(slice.as_mut_ptr(), 1 as *mut i8);
+    /// assert_eq!(slice.as_mut_ptr(), NonNull::<i8>::dangling().as_ptr());
     /// ```
     #[inline]
     #[must_use]
diff --git a/library/core/src/ptr/unique.rs b/library/core/src/ptr/unique.rs
index cff68f64f78..29398cbeb23 100644
--- a/library/core/src/ptr/unique.rs
+++ b/library/core/src/ptr/unique.rs
@@ -73,7 +73,7 @@ impl<T: Sized> Unique<T> {
     pub const fn dangling() -> Self {
         // SAFETY: mem::align_of() returns a valid, non-null pointer. The
         // conditions to call new_unchecked() are thus respected.
-        unsafe { Unique::new_unchecked(mem::align_of::<T>() as *mut T) }
+        unsafe { Unique::new_unchecked(crate::ptr::invalid_mut::<T>(mem::align_of::<T>())) }
     }
 }
 
diff --git a/library/core/src/slice/ascii.rs b/library/core/src/slice/ascii.rs
index c02a6f2d78c..63d761d3c02 100644
--- a/library/core/src/slice/ascii.rs
+++ b/library/core/src/slice/ascii.rs
@@ -294,7 +294,7 @@ fn is_ascii(s: &[u8]) -> bool {
     // Paranoia check about alignment, since we're about to do a bunch of
     // unaligned loads. In practice this should be impossible barring a bug in
     // `align_offset` though.
-    debug_assert_eq!((word_ptr as usize) % mem::align_of::<usize>(), 0);
+    debug_assert_eq!((word_ptr.addr()) % mem::align_of::<usize>(), 0);
 
     // Read subsequent words until the last aligned word, excluding the last
     // aligned word by itself to be done in tail check later, to ensure that
@@ -302,9 +302,9 @@ fn is_ascii(s: &[u8]) -> bool {
     while byte_pos < len - USIZE_SIZE {
         debug_assert!(
             // Sanity check that the read is in bounds
-            (word_ptr as usize + USIZE_SIZE) <= (start.wrapping_add(len) as usize) &&
+            (word_ptr.addr() + USIZE_SIZE) <= (start.wrapping_add(len).addr()) &&
             // And that our assumptions about `byte_pos` hold.
-            (word_ptr as usize) - (start as usize) == byte_pos
+            (word_ptr.addr()) - (start.addr()) == byte_pos
         );
 
         // SAFETY: We know `word_ptr` is properly aligned (because of
diff --git a/library/core/src/slice/iter/macros.rs b/library/core/src/slice/iter/macros.rs
index cf15756868e..96ead49dd6a 100644
--- a/library/core/src/slice/iter/macros.rs
+++ b/library/core/src/slice/iter/macros.rs
@@ -20,13 +20,13 @@ macro_rules! len {
         if size == 0 {
             // This _cannot_ use `unchecked_sub` because we depend on wrapping
             // to represent the length of long ZST slice iterators.
-            ($self.end as usize).wrapping_sub(start.as_ptr() as usize)
+            ($self.end.addr()).wrapping_sub(start.as_ptr().addr())
         } else {
             // We know that `start <= end`, so can do better than `offset_from`,
             // which needs to deal in signed.  By setting appropriate flags here
             // we can tell LLVM this, which helps it remove bounds checks.
             // SAFETY: By the type invariant, `start <= end`
-            let diff = unsafe { unchecked_sub($self.end as usize, start.as_ptr() as usize) };
+            let diff = unsafe { unchecked_sub($self.end.addr(), start.as_ptr().addr()) };
             // By also telling LLVM that the pointers are apart by an exact
             // multiple of the type size, it can optimize `len() == 0` down to
             // `start == end` instead of `(end - start) < size`.
diff --git a/library/core/src/slice/sort.rs b/library/core/src/slice/sort.rs
index 2ba0e5320d7..5cf08b5740e 100644
--- a/library/core/src/slice/sort.rs
+++ b/library/core/src/slice/sort.rs
@@ -269,7 +269,7 @@ where
     // Returns the number of elements between pointers `l` (inclusive) and `r` (exclusive).
     fn width<T>(l: *mut T, r: *mut T) -> usize {
         assert!(mem::size_of::<T>() > 0);
-        (r as usize - l as usize) / mem::size_of::<T>()
+        (r.addr() - l.addr()) / mem::size_of::<T>()
     }
 
     loop {
diff --git a/library/std/src/backtrace.rs b/library/std/src/backtrace.rs
index 94e6070c0f7..fded482095a 100644
--- a/library/std/src/backtrace.rs
+++ b/library/std/src/backtrace.rs
@@ -293,7 +293,7 @@ impl Backtrace {
         if !Backtrace::enabled() {
             return Backtrace { inner: Inner::Disabled };
         }
-        Backtrace::create(Backtrace::capture as usize)
+        Backtrace::create((Backtrace::capture as *mut ()).addr())
     }
 
     /// Forcibly captures a full backtrace, regardless of environment variable
@@ -308,7 +308,7 @@ impl Backtrace {
     /// parts of code.
     #[inline(never)] // want to make sure there's a frame here to remove
     pub fn force_capture() -> Backtrace {
-        Backtrace::create(Backtrace::force_capture as usize)
+        Backtrace::create((Backtrace::force_capture as *mut ()).addr())
     }
 
     /// Forcibly captures a disabled backtrace, regardless of environment
@@ -330,7 +330,7 @@ impl Backtrace {
                     frame: RawFrame::Actual(frame.clone()),
                     symbols: Vec::new(),
                 });
-                if frame.symbol_address() as usize == ip && actual_start.is_none() {
+                if frame.symbol_address().addr() == ip && actual_start.is_none() {
                     actual_start = Some(frames.len());
                 }
                 true
@@ -493,7 +493,7 @@ impl RawFrame {
         match self {
             RawFrame::Actual(frame) => frame.ip(),
             #[cfg(test)]
-            RawFrame::Fake => 1 as *mut c_void,
+            RawFrame::Fake => ptr::invalid_mut(1),
         }
     }
 }
diff --git a/library/std/src/io/error/repr_bitpacked.rs b/library/std/src/io/error/repr_bitpacked.rs
index 208d5a80c5a..7cc1c701064 100644
--- a/library/std/src/io/error/repr_bitpacked.rs
+++ b/library/std/src/io/error/repr_bitpacked.rs
@@ -106,7 +106,7 @@ use super::{Custom, ErrorData, ErrorKind, SimpleMessage};
 use alloc::boxed::Box;
 use core::marker::PhantomData;
 use core::mem::{align_of, size_of};
-use core::ptr::NonNull;
+use core::ptr::{self, NonNull};
 
 // The 2 least-significant bits are used as tag.
 const TAG_MASK: usize = 0b11;
@@ -136,7 +136,7 @@ impl Repr {
         let p = Box::into_raw(b).cast::<u8>();
         // Should only be possible if an allocator handed out a pointer with
         // wrong alignment.
-        debug_assert_eq!((p as usize & TAG_MASK), 0);
+        debug_assert_eq!((p.addr() & TAG_MASK), 0);
         // Note: We know `TAG_CUSTOM <= size_of::<Custom>()` (static_assert at
         // end of file), and both the start and end of the expression must be
         // valid without address space wraparound due to `Box`'s semantics.
@@ -166,7 +166,7 @@ impl Repr {
     pub(super) fn new_os(code: i32) -> Self {
         let utagged = ((code as usize) << 32) | TAG_OS;
         // Safety: `TAG_OS` is not zero, so the result of the `|` is not 0.
-        let res = Self(unsafe { NonNull::new_unchecked(utagged as *mut ()) }, PhantomData);
+        let res = Self(unsafe { NonNull::new_unchecked(ptr::invalid_mut(utagged)) }, PhantomData);
         // quickly smoke-check we encoded the right thing (This generally will
         // only run in libstd's tests, unless the user uses -Zbuild-std)
         debug_assert!(
@@ -180,7 +180,7 @@ impl Repr {
     pub(super) fn new_simple(kind: ErrorKind) -> Self {
         let utagged = ((kind as usize) << 32) | TAG_SIMPLE;
         // Safety: `TAG_SIMPLE` is not zero, so the result of the `|` is not 0.
-        let res = Self(unsafe { NonNull::new_unchecked(utagged as *mut ()) }, PhantomData);
+        let res = Self(unsafe { NonNull::new_unchecked(ptr::invalid_mut(utagged)) }, PhantomData);
         // quickly smoke-check we encoded the right thing (This generally will
         // only run in libstd's tests, unless the user uses -Zbuild-std)
         debug_assert!(
@@ -238,7 +238,7 @@ unsafe fn decode_repr<C, F>(ptr: NonNull<()>, make_custom: F) -> ErrorData<C>
 where
     F: FnOnce(*mut Custom) -> C,
 {
-    let bits = ptr.as_ptr() as usize;
+    let bits = ptr.as_ptr().addr();
     match bits & TAG_MASK {
         TAG_OS => {
             let code = ((bits as i64) >> 32) as i32;
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index a464f2d4c74..133ced5f26c 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -275,6 +275,7 @@
 #![feature(extend_one)]
 #![feature(float_minimum_maximum)]
 #![feature(format_args_nl)]
+#![feature(strict_provenance)]
 #![feature(get_mut_unchecked)]
 #![feature(hashmap_internals)]
 #![feature(int_error_internals)]
diff --git a/library/std/src/os/windows/io/handle.rs b/library/std/src/os/windows/io/handle.rs
index 120af9f99dd..ee30cc8be6b 100644
--- a/library/std/src/os/windows/io/handle.rs
+++ b/library/std/src/os/windows/io/handle.rs
@@ -9,6 +9,7 @@ use crate::fs;
 use crate::io;
 use crate::marker::PhantomData;
 use crate::mem::forget;
+use crate::ptr;
 use crate::sys::c;
 use crate::sys::cvt;
 use crate::sys_common::{AsInner, FromInner, IntoInner};
@@ -182,7 +183,7 @@ impl OwnedHandle {
             return unsafe { Ok(Self::from_raw_handle(handle)) };
         }
 
-        let mut ret = 0 as c::HANDLE;
+        let mut ret = ptr::null_mut();
         cvt(unsafe {
             let cur_proc = c::GetCurrentProcess();
             c::DuplicateHandle(
diff --git a/library/std/src/os/windows/io/socket.rs b/library/std/src/os/windows/io/socket.rs
index a6b979cc22b..db93cd15d4a 100644
--- a/library/std/src/os/windows/io/socket.rs
+++ b/library/std/src/os/windows/io/socket.rs
@@ -129,6 +129,7 @@ impl OwnedSocket {
         }
     }
 
+    // FIXME(strict_provenance_magic): we defined RawSocket to be a u64 ;-;
     #[cfg(not(target_vendor = "uwp"))]
     pub(crate) fn set_no_inherit(&self) -> io::Result<()> {
         cvt(unsafe {
diff --git a/library/std/src/path.rs b/library/std/src/path.rs
index bcf5c9328b7..8ecea8ce07f 100644
--- a/library/std/src/path.rs
+++ b/library/std/src/path.rs
@@ -1449,8 +1449,8 @@ impl PathBuf {
         };
 
         // truncate until right after the file stem
-        let end_file_stem = file_stem[file_stem.len()..].as_ptr() as usize;
-        let start = os_str_as_u8_slice(&self.inner).as_ptr() as usize;
+        let end_file_stem = file_stem[file_stem.len()..].as_ptr().addr();
+        let start = os_str_as_u8_slice(&self.inner).as_ptr().addr();
         let v = self.as_mut_vec();
         v.truncate(end_file_stem.wrapping_sub(start));
 
diff --git a/library/std/src/sync/once.rs b/library/std/src/sync/once.rs
index 511de863dc5..d2dd4c075d2 100644
--- a/library/std/src/sync/once.rs
+++ b/library/std/src/sync/once.rs
@@ -91,9 +91,12 @@ use crate::cell::Cell;
 use crate::fmt;
 use crate::marker;
 use crate::panic::{RefUnwindSafe, UnwindSafe};
-use crate::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use crate::ptr;
+use crate::sync::atomic::{AtomicBool, AtomicPtr, Ordering};
 use crate::thread::{self, Thread};
 
+type Masked = ();
+
 /// A synchronization primitive which can be used to run a one-time global
 /// initialization. Useful for one-time initialization for FFI or related
 /// functionality. This type can only be constructed with [`Once::new()`].
@@ -113,7 +116,7 @@ use crate::thread::{self, Thread};
 pub struct Once {
     // `state_and_queue` is actually a pointer to a `Waiter` with extra state
     // bits, so we add the `PhantomData` appropriately.
-    state_and_queue: AtomicUsize,
+    state_and_queue: AtomicPtr<Masked>,
     _marker: marker::PhantomData<*const Waiter>,
 }
 
@@ -136,7 +139,7 @@ impl RefUnwindSafe for Once {}
 #[derive(Debug)]
 pub struct OnceState {
     poisoned: bool,
-    set_state_on_drop_to: Cell<usize>,
+    set_state_on_drop_to: Cell<*mut Masked>,
 }
 
 /// Initialization value for static [`Once`] values.
@@ -184,8 +187,8 @@ struct Waiter {
 // Every node is a struct on the stack of a waiting thread.
 // Will wake up the waiters when it gets dropped, i.e. also on panic.
 struct WaiterQueue<'a> {
-    state_and_queue: &'a AtomicUsize,
-    set_state_on_drop_to: usize,
+    state_and_queue: &'a AtomicPtr<Masked>,
+    set_state_on_drop_to: *mut Masked,
 }
 
 impl Once {
@@ -195,7 +198,10 @@ impl Once {
     #[rustc_const_stable(feature = "const_once_new", since = "1.32.0")]
     #[must_use]
     pub const fn new() -> Once {
-        Once { state_and_queue: AtomicUsize::new(INCOMPLETE), _marker: marker::PhantomData }
+        Once {
+            state_and_queue: AtomicPtr::new(ptr::invalid_mut(INCOMPLETE)),
+            _marker: marker::PhantomData,
+        }
     }
 
     /// Performs an initialization routine once and only once. The given closure
@@ -376,7 +382,7 @@ impl Once {
         // operations visible to us, and, this being a fast path, weaker
         // ordering helps with performance. This `Acquire` synchronizes with
         // `Release` operations on the slow path.
-        self.state_and_queue.load(Ordering::Acquire) == COMPLETE
+        self.state_and_queue.load(Ordering::Acquire).addr() == COMPLETE
     }
 
     // This is a non-generic function to reduce the monomorphization cost of
@@ -395,7 +401,7 @@ impl Once {
     fn call_inner(&self, ignore_poisoning: bool, init: &mut dyn FnMut(&OnceState)) {
         let mut state_and_queue = self.state_and_queue.load(Ordering::Acquire);
         loop {
-            match state_and_queue {
+            match state_and_queue.addr() {
                 COMPLETE => break,
                 POISONED if !ignore_poisoning => {
                     // Panic to propagate the poison.
@@ -405,7 +411,7 @@ impl Once {
                     // Try to register this thread as the one RUNNING.
                     let exchange_result = self.state_and_queue.compare_exchange(
                         state_and_queue,
-                        RUNNING,
+                        ptr::invalid_mut(RUNNING),
                         Ordering::Acquire,
                         Ordering::Acquire,
                     );
@@ -417,13 +423,13 @@ impl Once {
                     // wake them up on drop.
                     let mut waiter_queue = WaiterQueue {
                         state_and_queue: &self.state_and_queue,
-                        set_state_on_drop_to: POISONED,
+                        set_state_on_drop_to: ptr::invalid_mut(POISONED),
                     };
                     // Run the initialization function, letting it know if we're
                     // poisoned or not.
                     let init_state = OnceState {
-                        poisoned: state_and_queue == POISONED,
-                        set_state_on_drop_to: Cell::new(COMPLETE),
+                        poisoned: state_and_queue.addr() == POISONED,
+                        set_state_on_drop_to: Cell::new(ptr::invalid_mut(COMPLETE)),
                     };
                     init(&init_state);
                     waiter_queue.set_state_on_drop_to = init_state.set_state_on_drop_to.get();
@@ -432,7 +438,7 @@ impl Once {
                 _ => {
                     // All other values must be RUNNING with possibly a
                     // pointer to the waiter queue in the more significant bits.
-                    assert!(state_and_queue & STATE_MASK == RUNNING);
+                    assert!(state_and_queue.addr() & STATE_MASK == RUNNING);
                     wait(&self.state_and_queue, state_and_queue);
                     state_and_queue = self.state_and_queue.load(Ordering::Acquire);
                 }
@@ -441,13 +447,13 @@ impl Once {
     }
 }
 
-fn wait(state_and_queue: &AtomicUsize, mut current_state: usize) {
+fn wait(state_and_queue: &AtomicPtr<Masked>, mut current_state: *mut Masked) {
     // Note: the following code was carefully written to avoid creating a
     // mutable reference to `node` that gets aliased.
     loop {
         // Don't queue this thread if the status is no longer running,
         // otherwise we will not be woken up.
-        if current_state & STATE_MASK != RUNNING {
+        if current_state.addr() & STATE_MASK != RUNNING {
             return;
         }
 
@@ -455,15 +461,15 @@ fn wait(state_and_queue: &AtomicUsize, mut current_state: usize) {
         let node = Waiter {
             thread: Cell::new(Some(thread::current())),
             signaled: AtomicBool::new(false),
-            next: (current_state & !STATE_MASK) as *const Waiter,
+            next: current_state.with_addr(current_state.addr() & !STATE_MASK) as *const Waiter,
         };
-        let me = &node as *const Waiter as usize;
+        let me = &node as *const Waiter as *const Masked as *mut Masked;
 
         // Try to slide in the node at the head of the linked list, making sure
         // that another thread didn't just replace the head of the linked list.
         let exchange_result = state_and_queue.compare_exchange(
             current_state,
-            me | RUNNING,
+            me.with_addr(me.addr() | RUNNING),
             Ordering::Release,
             Ordering::Relaxed,
         );
@@ -502,7 +508,7 @@ impl Drop for WaiterQueue<'_> {
             self.state_and_queue.swap(self.set_state_on_drop_to, Ordering::AcqRel);
 
         // We should only ever see an old state which was RUNNING.
-        assert_eq!(state_and_queue & STATE_MASK, RUNNING);
+        assert_eq!(state_and_queue.addr() & STATE_MASK, RUNNING);
 
         // Walk the entire linked list of waiters and wake them up (in lifo
         // order, last to register is first to wake up).
@@ -511,7 +517,8 @@ impl Drop for WaiterQueue<'_> {
             // free `node` if there happens to be has a spurious wakeup.
             // So we have to take out the `thread` field and copy the pointer to
             // `next` first.
-            let mut queue = (state_and_queue & !STATE_MASK) as *const Waiter;
+            let mut queue =
+                state_and_queue.with_addr(state_and_queue.addr() & !STATE_MASK) as *const Waiter;
             while !queue.is_null() {
                 let next = (*queue).next;
                 let thread = (*queue).thread.take().unwrap();
@@ -568,6 +575,6 @@ impl OnceState {
     /// Poison the associated [`Once`] without explicitly panicking.
     // NOTE: This is currently only exposed for the `lazy` module
     pub(crate) fn poison(&self) {
-        self.set_state_on_drop_to.set(POISONED);
+        self.set_state_on_drop_to.set(ptr::invalid_mut(POISONED));
     }
 }
diff --git a/library/std/src/sys/windows/alloc.rs b/library/std/src/sys/windows/alloc.rs
index 2fe71f9f28d..fdc81cdea7d 100644
--- a/library/std/src/sys/windows/alloc.rs
+++ b/library/std/src/sys/windows/alloc.rs
@@ -159,7 +159,7 @@ unsafe fn allocate(layout: Layout, zeroed: bool) -> *mut u8 {
         // Create a correctly aligned pointer offset from the start of the allocated block,
         // and write a header before it.
 
-        let offset = layout.align() - (ptr as usize & (layout.align() - 1));
+        let offset = layout.align() - (ptr.addr() & (layout.align() - 1));
         // SAFETY: `MIN_ALIGN` <= `offset` <= `layout.align()` and the size of the allocated
         // block is `layout.align() + layout.size()`. `aligned` will thus be a correctly aligned
         // pointer inside the allocated block with at least `layout.size()` bytes after it and at
diff --git a/library/std/src/sys/windows/c.rs b/library/std/src/sys/windows/c.rs
index 9b61b2476d5..0edf43e5d9d 100644
--- a/library/std/src/sys/windows/c.rs
+++ b/library/std/src/sys/windows/c.rs
@@ -173,7 +173,7 @@ pub const PROGRESS_CONTINUE: DWORD = 0;
 
 pub const E_NOTIMPL: HRESULT = 0x80004001u32 as HRESULT;
 
-pub const INVALID_HANDLE_VALUE: HANDLE = !0 as HANDLE;
+pub const INVALID_HANDLE_VALUE: HANDLE = ptr::invalid_mut(!0);
 
 pub const FACILITY_NT_BIT: DWORD = 0x1000_0000;
 
diff --git a/library/std/src/sys/windows/compat.rs b/library/std/src/sys/windows/compat.rs
index cbd3366b189..a914a3bcc12 100644
--- a/library/std/src/sys/windows/compat.rs
+++ b/library/std/src/sys/windows/compat.rs
@@ -88,7 +88,7 @@ macro_rules! compat_fn {
                 let symbol_name: *const u8 = concat!(stringify!($symbol), "\0").as_ptr();
                 let module_handle = $crate::sys::c::GetModuleHandleA(module_name as *const i8);
                 if !module_handle.is_null() {
-                    match $crate::sys::c::GetProcAddress(module_handle, symbol_name as *const i8) as usize {
+                    match $crate::sys::c::GetProcAddress(module_handle, symbol_name as *const i8).addr() {
                         0 => {}
                         n => {
                             PTR = Some(mem::transmute::<usize, F>(n));
diff --git a/library/std/src/sys/windows/fs.rs b/library/std/src/sys/windows/fs.rs
index d6c40a15329..95903899297 100644
--- a/library/std/src/sys/windows/fs.rs
+++ b/library/std/src/sys/windows/fs.rs
@@ -57,6 +57,9 @@ pub struct DirEntry {
     data: c::WIN32_FIND_DATAW,
 }
 
+unsafe impl Send for OpenOptions {}
+unsafe impl Sync for OpenOptions {}
+
 #[derive(Clone, Debug)]
 pub struct OpenOptions {
     // generic
@@ -72,7 +75,7 @@ pub struct OpenOptions {
     attributes: c::DWORD,
     share_mode: c::DWORD,
     security_qos_flags: c::DWORD,
-    security_attributes: usize, // FIXME: should be a reference
+    security_attributes: c::LPSECURITY_ATTRIBUTES,
 }
 
 #[derive(Clone, PartialEq, Eq, Debug)]
@@ -187,7 +190,7 @@ impl OpenOptions {
             share_mode: c::FILE_SHARE_READ | c::FILE_SHARE_WRITE | c::FILE_SHARE_DELETE,
             attributes: 0,
             security_qos_flags: 0,
-            security_attributes: 0,
+            security_attributes: ptr::null_mut(),
         }
     }
 
@@ -228,7 +231,7 @@ impl OpenOptions {
         self.security_qos_flags = flags | c::SECURITY_SQOS_PRESENT;
     }
     pub fn security_attributes(&mut self, attrs: c::LPSECURITY_ATTRIBUTES) {
-        self.security_attributes = attrs as usize;
+        self.security_attributes = attrs;
     }
 
     fn get_access_mode(&self) -> io::Result<c::DWORD> {
@@ -289,7 +292,7 @@ impl File {
                 path.as_ptr(),
                 opts.get_access_mode()?,
                 opts.share_mode,
-                opts.security_attributes as *mut _,
+                opts.security_attributes,
                 opts.get_creation_mode()?,
                 opts.get_flags_and_attributes(),
                 ptr::null_mut(),
diff --git a/library/std/src/sys/windows/mod.rs b/library/std/src/sys/windows/mod.rs
index 62814eaaa56..87e3fec6353 100644
--- a/library/std/src/sys/windows/mod.rs
+++ b/library/std/src/sys/windows/mod.rs
@@ -136,7 +136,7 @@ pub fn unrolled_find_u16s(needle: u16, haystack: &[u16]) -> Option<usize> {
             ($($n:literal,)+) => {
                 $(
                     if start[$n] == needle {
-                        return Some((&start[$n] as *const u16 as usize - ptr as usize) / 2);
+                        return Some(((&start[$n] as *const u16).addr() - ptr.addr()) / 2);
                     }
                 )+
             }
@@ -149,7 +149,7 @@ pub fn unrolled_find_u16s(needle: u16, haystack: &[u16]) -> Option<usize> {
 
     for c in start {
         if *c == needle {
-            return Some((c as *const u16 as usize - ptr as usize) / 2);
+            return Some(((c as *const u16).addr() - ptr.addr()) / 2);
         }
     }
     None
diff --git a/library/std/src/sys/windows/os.rs b/library/std/src/sys/windows/os.rs
index 450bceae000..bcac996c024 100644
--- a/library/std/src/sys/windows/os.rs
+++ b/library/std/src/sys/windows/os.rs
@@ -134,7 +134,7 @@ impl Drop for Env {
 pub fn env() -> Env {
     unsafe {
         let ch = c::GetEnvironmentStringsW();
-        if ch as usize == 0 {
+        if ch.is_null() {
             panic!("failure getting env string from OS: {}", io::Error::last_os_error());
         }
         Env { base: ch, cur: ch }
diff --git a/library/std/src/sys/windows/thread_parker.rs b/library/std/src/sys/windows/thread_parker.rs
index 5888ee8e34b..3497da51dee 100644
--- a/library/std/src/sys/windows/thread_parker.rs
+++ b/library/std/src/sys/windows/thread_parker.rs
@@ -60,7 +60,7 @@
 use crate::convert::TryFrom;
 use crate::ptr;
 use crate::sync::atomic::{
-    AtomicI8, AtomicUsize,
+    AtomicI8, AtomicPtr,
     Ordering::{Acquire, Relaxed, Release},
 };
 use crate::sys::{c, dur2timeout};
@@ -217,8 +217,8 @@ impl Parker {
 }
 
 fn keyed_event_handle() -> c::HANDLE {
-    const INVALID: usize = !0;
-    static HANDLE: AtomicUsize = AtomicUsize::new(INVALID);
+    const INVALID: c::HANDLE = ptr::invalid_mut(!0);
+    static HANDLE: AtomicPtr<libc::c_void> = AtomicPtr::new(INVALID);
     match HANDLE.load(Relaxed) {
         INVALID => {
             let mut handle = c::INVALID_HANDLE_VALUE;
@@ -233,7 +233,7 @@ fn keyed_event_handle() -> c::HANDLE {
                     r => panic!("Unable to create keyed event handle: error {r}"),
                 }
             }
-            match HANDLE.compare_exchange(INVALID, handle as usize, Relaxed, Relaxed) {
+            match HANDLE.compare_exchange(INVALID, handle, Relaxed, Relaxed) {
                 Ok(_) => handle,
                 Err(h) => {
                     // Lost the race to another thread initializing HANDLE before we did.
@@ -241,10 +241,10 @@ fn keyed_event_handle() -> c::HANDLE {
                     unsafe {
                         c::CloseHandle(handle);
                     }
-                    h as c::HANDLE
+                    h
                 }
             }
         }
-        handle => handle as c::HANDLE,
+        handle => handle,
     }
 }
diff --git a/library/std/src/sys_common/condvar/check.rs b/library/std/src/sys_common/condvar/check.rs
index 47aff060d6f..7671850ac55 100644
--- a/library/std/src/sys_common/condvar/check.rs
+++ b/library/std/src/sys_common/condvar/check.rs
@@ -1,4 +1,5 @@
-use crate::sync::atomic::{AtomicUsize, Ordering};
+use crate::ptr;
+use crate::sync::atomic::{AtomicPtr, Ordering};
 use crate::sys::locks as imp;
 use crate::sys_common::mutex::MovableMutex;
 
@@ -13,17 +14,18 @@ impl CondvarCheck for Box<imp::Mutex> {
 }
 
 pub struct SameMutexCheck {
-    addr: AtomicUsize,
+    addr: AtomicPtr<()>,
 }
 
 #[allow(dead_code)]
 impl SameMutexCheck {
     pub const fn new() -> Self {
-        Self { addr: AtomicUsize::new(0) }
+        Self { addr: AtomicPtr::new(ptr::null_mut()) }
     }
     pub fn verify(&self, mutex: &MovableMutex) {
-        let addr = mutex.raw() as *const imp::Mutex as usize;
-        match self.addr.compare_exchange(0, addr, Ordering::SeqCst, Ordering::SeqCst) {
+        let addr = mutex.raw() as *const imp::Mutex as *const () as *mut _;
+        match self.addr.compare_exchange(ptr::null_mut(), addr, Ordering::SeqCst, Ordering::SeqCst)
+        {
             Ok(_) => {}               // Stored the address
             Err(n) if n == addr => {} // Lost a race to store the same address
             _ => panic!("attempted to use a condition variable with two mutexes"),
diff --git a/library/std/src/thread/local.rs b/library/std/src/thread/local.rs
index a100444f049..ca29261b1c9 100644
--- a/library/std/src/thread/local.rs
+++ b/library/std/src/thread/local.rs
@@ -1071,7 +1071,7 @@ pub mod os {
         pub unsafe fn get(&'static self, init: impl FnOnce() -> T) -> Option<&'static T> {
             // SAFETY: See the documentation for this method.
             let ptr = unsafe { self.os.get() as *mut Value<T> };
-            if ptr as usize > 1 {
+            if ptr.addr() > 1 {
                 // SAFETY: the check ensured the pointer is safe (its destructor
                 // is not running) + it is coming from a trusted source (self).
                 if let Some(ref value) = unsafe { (*ptr).inner.get() } {
@@ -1090,7 +1090,7 @@ pub mod os {
             // SAFETY: No mutable references are ever handed out meaning getting
             // the value is ok.
             let ptr = unsafe { self.os.get() as *mut Value<T> };
-            if ptr as usize == 1 {
+            if ptr.addr() == 1 {
                 // destructor is running
                 return None;
             }
@@ -1130,7 +1130,7 @@ pub mod os {
         unsafe {
             let ptr = Box::from_raw(ptr as *mut Value<T>);
             let key = ptr.key;
-            key.os.set(1 as *mut u8);
+            key.os.set(ptr::invalid_mut(1));
             drop(ptr);
             key.os.set(ptr::null_mut());
         }