WIP PROOF-OF-CONCEPT: handle all the fallout in the libs

Still working on this, but it seems to largely be a lot of `as usize` -> `.addr()`

Author: Gankra

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)]

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

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);
             }

library/alloc/src/sync.rs

@@ -1745,7 +1745,7 @@ 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)) } }
     }
 }
 

library/alloc/src/vec/into_iter.rs

@@ -154,7 +154,7 @@ 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 }
         };

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

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;

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);
         }
     }

library/core/src/intrinsics.rs

@@ -987,8 +987,8 @@ extern "rust-intrinsic" {
     ///     std::mem::transmute::<&i32, usize>(ptr)
     /// };
     ///
-    /// // Use an `as` cast instead
-    /// let ptr_num_cast = ptr as *const i32 as usize;
+    /// // Use `.addr()` instead
+    /// let ptr_num_cast = (ptr as *const i32).addr();
     /// ```
     ///
     /// Turning a `*mut T` into an `&mut T`:
@@ -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,

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());
     /// ```
     #[inline]
     #[must_use]