Fix MIRI under tree borrows

src/lib.rs

@@ -8,6 +8,7 @@
 	not(debug_assertions),
 	deny(missing_docs, clippy::missing_docs_in_private_items)
 )]
+#![cfg_attr(miri, feature(strict_provenance))]
 #![deny(unconditional_recursion)]
 #![allow(
 	clippy::declare_interior_mutable_const,

src/ptr/span.rs

@@ -273,10 +273,17 @@ where
 	/// [`::new`]: Self::new
 	#[cfg(feature = "alloc")]
 	pub(crate) unsafe fn set_address(&mut self, addr: Address<M, T>) {
-		let mut addr_value = addr.to_const() as usize;
-		addr_value &= Self::PTR_ADDR_MASK;
-		addr_value |= self.ptr.as_ptr() as usize & Self::PTR_HEAD_MASK;
-		self.ptr = NonNull::new_unchecked(addr_value as *mut ())
+		let map = |mut addr_value| {
+			addr_value &= Self::PTR_ADDR_MASK;
+			addr_value |= self.ptr.as_ptr() as usize & Self::PTR_HEAD_MASK;
+			addr_value
+		};
+
+		#[cfg(miri)]
+		let new_addr = addr.to_const().map_addr(map).cast::<()>().cast_mut();
+		#[cfg(not(miri))]
+		let new_addr = map(addr.to_const() as usize) as *mut ();
+		self.ptr = NonNull::new_unchecked(new_addr);
 	}
 
 	/// Gets the starting bit index of the referent region.
@@ -313,11 +320,19 @@ where
 	#[cfg(feature = "alloc")]
 	pub(crate) unsafe fn set_head(&mut self, head: BitIdx<T::Mem>) {
 		let head = head.into_inner() as usize;
-		let mut ptr = self.ptr.as_ptr() as usize;
+		let map = |mut ptr_value| {
+			ptr_value &= Self::PTR_ADDR_MASK;
+			ptr_value |= head >> Self::LEN_HEAD_BITS;
+			ptr_value
+		};
+
+		let ptr = self.ptr.as_ptr();
 
-		ptr &= Self::PTR_ADDR_MASK;
-		ptr |= head >> Self::LEN_HEAD_BITS;
-		self.ptr = NonNull::new_unchecked(ptr as *mut ());
+		#[cfg(miri)]
+		let new_ptr = ptr.map_addr(map);
+		#[cfg(not(miri))]
+		let new_ptr = map(ptr as usize) as *mut ();
+		self.ptr = NonNull::new_unchecked(new_ptr);
 
 		self.len &= !Self::LEN_HEAD_MASK;
 		self.len |= head & Self::LEN_HEAD_MASK;

src/ptr/tests.rs

@@ -23,13 +23,14 @@ fn free_functions() {
 
 	let one = BitPtr::<Mut, u8, Lsb0>::from_slice_mut(&mut a[..]);
 	let two = one.wrapping_add(8);
-	let three = BitPtr::<Mut, u16, Msb0>::from_mut(&mut b);
-	let four = three.wrapping_add(8);
 
 	unsafe {
 		bv_ptr::copy(two.to_const(), one, 8);
 	}
 	assert_eq!(a[0], !0);
+
+	let one = BitPtr::<Mut, u8, Lsb0>::from_slice_mut(&mut a[..]);
+	let three = BitPtr::<Mut, u16, Msb0>::from_mut(&mut b);
 	unsafe {
 		bv_ptr::copy(three.to_const(), one, 8);
 	}
@@ -43,6 +44,8 @@ fn free_functions() {
 	assert_eq!(a[1], 0);
 	assert_eq!(b, !0);
 
+	let three = BitPtr::<Mut, u16, Msb0>::from_mut(&mut b);
+	let four = three.wrapping_add(8);
 	unsafe {
 		bv_ptr::write_bits(four, false, 8);
 	}

src/slice.rs

@@ -3,6 +3,7 @@
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 use core::{
+	cell::UnsafeCell,
 	marker::PhantomData,
 	ops::RangeBounds,
 };
@@ -82,7 +83,7 @@ where
 	///
 	/// See `ptr::span` for more information on the encoding scheme used in
 	/// references to `BitSlice`.
-	_mem: [()],
+	_mem: [UnsafeCell<()>],
 }
 
 /// Constructors.

src/slice/traits.rs

@@ -20,6 +20,7 @@ use core::{
 		Hash,
 		Hasher,
 	},
+	panic::RefUnwindSafe,
 	str,
 };
 
@@ -541,6 +542,13 @@ where
 	}
 }
 
+impl<T, O> RefUnwindSafe for BitSlice<T, O>
+where
+	T: BitStore + RefUnwindSafe,
+	O: BitOrder,
+{
+}
+
 #[doc = include_str!("../../doc/slice/threadsafe.md")]
 unsafe impl<T, O> Send for BitSlice<T, O>
 where