strict provenance conformance

src/lib.rs

@@ -117,6 +117,8 @@
 //! [`unsize_stable`]: Vec::unsize_stable
 
 #![cfg_attr(feature = "unstable", feature(coerce_unsized))]
+#![cfg_attr(feature = "unstable", feature(set_ptr_value))]
+#![cfg_attr(feature = "unstable", feature(pointer_byte_offsets))]
 #![warn(missing_docs)]
 #![warn(clippy::pedantic)]
 #![warn(clippy::nursery)]

src/ptr_ext.rs

@@ -1,9 +1,11 @@
 use std::{
     alloc::{alloc, Layout},
     mem::size_of_val,
-    ptr::addr_of_mut,
 };
 
+#[cfg(not(feature = "unstable"))]
+use std::ptr::addr_of_mut;
+
 use self::__priv::Sealed;
 
 mod __priv {
@@ -52,10 +54,18 @@ impl<T: ?Sized> PtrExt for *const T {
         self.with_addr(addr.addr())
     }
 
-    fn with_addr(mut self, addr: usize) -> Self {
-        // TODO: aaaaand this is cheating. sorry yall, cant do this until `set_ptr_value` lands
-        unsafe { *addr_of_mut!(self).cast() = addr }
-        self
+    fn with_addr(self, addr: usize) -> Self {
+        #[cfg(feature = "unstable")]
+        {
+            self.wrapping_byte_sub(self.addr()).wrapping_byte_add(addr)
+        }
+        #[cfg(not(feature = "unstable"))]
+        {
+            let mut this = self;
+            // TODO: aaaaand this is cheating. sorry yall, cant do this until `set_ptr_value` lands
+            unsafe { *addr_of_mut!(this).cast() = addr }
+            this
+        }
     }
 
     unsafe fn get_end(self) -> Self {
@@ -103,10 +113,18 @@ impl<T: ?Sized> PtrExt for *mut T {
         self.with_addr(addr.addr())
     }
 
-    fn with_addr(mut self, addr: usize) -> Self {
-        // TODO: aaaaand this is cheating. sorry yall, cant do this until `set_ptr_value` lands
-        unsafe { *addr_of_mut!(self).cast() = addr }
-        self
+    fn with_addr(self, addr: usize) -> Self {
+        #[cfg(feature = "unstable")]
+        {
+            self.wrapping_byte_sub(self.addr()).wrapping_byte_add(addr)
+        }
+        #[cfg(not(feature = "unstable"))]
+        {
+            let mut this = self;
+            // TODO: aaaaand this is cheating. sorry yall, cant do this until `set_ptr_value` lands
+            unsafe { *addr_of_mut!(this).cast() = addr }
+            this
+        }
     }
 
     unsafe fn get_end(self) -> Self {
@@ -156,7 +174,14 @@ impl<T: ?Sized> ConstPtrExt for *const T {
     // }
 
     fn with_meta_from<U: ?Sized>(self, ptr: *const U) -> *const U {
-        ptr.with_addr_from(self)
+        #[cfg(feature = "unstable")]
+        {
+            self.with_metadata_of(ptr)
+        }
+        #[cfg(not(feature = "unstable"))]
+        {
+            ptr.with_addr_from(self)
+        }
     }
 }
 
@@ -179,6 +204,13 @@ impl<T: ?Sized> MutPtrExt for *mut T {
     // }
 
     fn with_meta_from<U: ?Sized>(self, ptr: *const U) -> *mut U {
-        ptr.with_addr_from(self) as _
+        #[cfg(feature = "unstable")]
+        {
+            self.with_metadata_of(ptr as _)
+        }
+        #[cfg(not(feature = "unstable"))]
+        {
+            ptr.with_addr_from(self) as _
+        }
     }
 }

src/test.rs

@@ -1,4 +1,4 @@
-//! Always use `cargo miri test`, and never just `cargo test`.
+//! Always use `cargo miri test --all-features`, and never just `cargo test`.
 
 use rand::{thread_rng, Rng};