Apply CR suggestions; add real tracking issue

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -377,6 +377,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         }
 
                         let pointee_layout = self.layout_of(substs.type_at(0))?;
+                        // This re-interprets an isize at ret_layout, but we already checked
+                        // that if ret_layout is usize, then the result must be non-negative.
                         let val = ImmTy::from_scalar(val, ret_layout);
                         let size = ImmTy::from_int(pointee_layout.size.bytes(), ret_layout);
                         self.exact_div(&val, &size, dest)?;

library/alloc/src/lib.rs

@@ -127,7 +127,7 @@
 #![feature(pattern)]
 #![feature(ptr_internals)]
 #![feature(ptr_metadata)]
-#![feature(ptr_unsigned_offset_from)]
+#![feature(ptr_sub_ptr)]
 #![feature(receiver_trait)]
 #![feature(set_ptr_value)]
 #![feature(slice_group_by)]

library/core/src/lib.rs

@@ -126,6 +126,7 @@
 #![feature(const_option)]
 #![feature(const_option_ext)]
 #![feature(const_pin)]
+#![feature(const_ptr_sub_ptr)]
 #![feature(const_replace)]
 #![feature(const_ptr_as_ref)]
 #![feature(const_ptr_is_null)]

library/core/src/ptr/const_ptr.rs

@@ -627,7 +627,7 @@ impl<T: ?Sized> *const T {
     /// to [`sub`](#method.sub)).  The following are all equivalent, assuming
     /// that their safety preconditions are met:
     /// ```rust
-    /// # #![feature(ptr_unsigned_offset_from)]
+    /// # #![feature(ptr_sub_ptr)]
     /// # unsafe fn blah(ptr: *const i32, origin: *const i32, count: usize) -> bool {
     /// ptr.sub_ptr(origin) == count
     /// # &&
@@ -656,7 +656,7 @@ impl<T: ?Sized> *const T {
     /// # Examples
     ///
     /// ```
-    /// #![feature(ptr_unsigned_offset_from)]
+    /// #![feature(ptr_sub_ptr)]
     ///
     /// let a = [0; 5];
     /// let ptr1: *const i32 = &a[1];
@@ -671,8 +671,8 @@ impl<T: ?Sized> *const T {
     /// // This would be incorrect, as the pointers are not correctly ordered:
     /// // ptr1.offset_from(ptr2)
     /// ```
-    #[unstable(feature = "ptr_unsigned_offset_from", issue = "88888888")]
-    #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "92980")]
+    #[unstable(feature = "ptr_sub_ptr", issue = "95892")]
+    #[rustc_const_unstable(feature = "const_ptr_sub_ptr", issue = "95892")]
     #[inline]
     pub const unsafe fn sub_ptr(self, origin: *const T) -> usize
     where

library/core/src/ptr/mut_ptr.rs

@@ -803,7 +803,7 @@ impl<T: ?Sized> *mut T {
     /// to [`sub`](#method.sub)).  The following are all equivalent, assuming
     /// that their safety preconditions are met:
     /// ```rust
-    /// # #![feature(ptr_unsigned_offset_from)]
+    /// # #![feature(ptr_sub_ptr)]
     /// # unsafe fn blah(ptr: *mut i32, origin: *mut i32, count: usize) -> bool {
     /// ptr.sub_ptr(origin) == count
     /// # &&
@@ -832,7 +832,7 @@ impl<T: ?Sized> *mut T {
     /// # Examples
     ///
     /// ```
-    /// #![feature(ptr_unsigned_offset_from)]
+    /// #![feature(ptr_sub_ptr)]
     ///
     /// let mut a = [0; 5];
     /// let p: *mut i32 = a.as_mut_ptr();
@@ -848,8 +848,8 @@ impl<T: ?Sized> *mut T {
     ///
     /// // This would be incorrect, as the pointers are not correctly ordered:
     /// // ptr1.offset_from(ptr2)
-    #[unstable(feature = "ptr_unsigned_offset_from", issue = "88888888")]
-    #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "92980")]
+    #[unstable(feature = "ptr_sub_ptr", issue = "95892")]
+    #[rustc_const_unstable(feature = "const_ptr_sub_ptr", issue = "95892")]
     #[inline]
     pub const unsafe fn sub_ptr(self, origin: *const T) -> usize
     where

src/test/ui/consts/offset_from.rs

@@ -1,7 +1,8 @@
 // run-pass
 
 #![feature(const_ptr_offset_from)]
-#![feature(ptr_unsigned_offset_from)]
+#![feature(const_ptr_sub_ptr)]
+#![feature(ptr_sub_ptr)]
 
 struct Struct {
     field: (),