Use "stable" version of the intrinsic on stage0

src/libcore/intrinsics.rs

@@ -1381,38 +1381,7 @@ extern "rust-intrinsic" {
 }
 
 #[cfg(stage0)]
-/// Computes the byte offset that needs to be applied to `ptr` in order to
-/// make it aligned to `align`.
-/// If it is not possible to align `ptr`, the implementation returns
-/// `usize::max_value()`.
-///
-/// There are no guarantees whatsover that offsetting the pointer will not
-/// overflow or go beyond the allocation that `ptr` points into.
-/// It is up to the caller to ensure that the returned offset is correct
-/// in all terms other than alignment.
-///
-/// # Examples
-///
-/// Accessing adjacent `u8` as `u16`
-///
-/// ```
-/// # #![feature(core_intrinsics)]
-/// # fn foo(n: usize) {
-/// # use std::intrinsics::align_offset;
-/// # use std::mem::align_of;
-/// # unsafe {
-/// let x = [5u8, 6u8, 7u8, 8u8, 9u8];
-/// let ptr = &x[n] as *const u8;
-/// let offset = align_offset(ptr as *const (), align_of::<u16>());
-/// if offset < x.len() - n - 1 {
-///     let u16_ptr = ptr.offset(offset as isize) as *const u16;
-///     assert_ne!(*u16_ptr, 500);
-/// } else {
-///     // while the pointer can be aligned via `offset`, it would point
-///     // outside the allocation
-/// }
-/// # } }
-/// ```
+/// remove me after the next release
 pub unsafe fn align_offset(ptr: *const (), align: usize) -> usize {
     let offset = ptr as usize % align;
     if offset == 0 {

src/libcore/ptr.rs

@@ -662,12 +662,22 @@ impl<T: ?Sized> *const T {
     /// }
     /// # } }
     /// ```
+    #[cfg(not(stage0))]
     #[unstable(feature = "align_offset", issue = "44488")]
     pub fn align_offset(self, align: usize) -> usize {
         unsafe {
             intrinsics::align_offset(self as *const _, align)
         }
     }
+
+    #[cfg(stage0)]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    /// remove me after the next release
+    pub fn align_offset(self, align: usize) -> usize {
+        unsafe {
+            intrinsics::align_offset(self as *const _, align)
+        }
+    }
 }
 
 #[lang = "mut_ptr"]
@@ -891,12 +901,22 @@ impl<T: ?Sized> *mut T {
     /// }
     /// # } }
     /// ```
+    #[cfg(not(stage0))]
     #[unstable(feature = "align_offset", issue = "44488")]
     pub fn align_offset(self, align: usize) -> usize {
         unsafe {
             intrinsics::align_offset(self as *const _, align)
         }
     }
+
+    #[cfg(stage0)]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    /// remove me after the next release
+    pub fn align_offset(self, align: usize) -> usize {
+        unsafe {
+            intrinsics::align_offset(self as *const _, align)
+        }
+    }
 }
 
 // Equality for pointers

src/libcore/str/mod.rs

@@ -23,7 +23,6 @@ use fmt;
 use iter::{Map, Cloned, FusedIterator};
 use slice::{self, SliceIndex};
 use mem;
-use intrinsics::align_offset;
 
 pub mod pattern;
 
@@ -1471,7 +1470,7 @@ fn run_utf8_validation(v: &[u8]) -> Result<(), Utf8Error> {
             let ptr = v.as_ptr();
             let align = unsafe {
                 // the offset is safe, because `index` is guaranteed inbounds
-                align_offset(ptr.offset(index as isize) as *const (), usize_bytes)
+                ptr.offset(index as isize).align_offset(usize_bytes)
             };
             if align == 0 {
                 while index < blocks_end {

src/libstd/lib.rs

@@ -242,6 +242,7 @@
 #![feature(allocator_internals)]
 #![feature(allow_internal_unsafe)]
 #![feature(allow_internal_unstable)]
+#![cfg_attr(not(stage0), feature(align_offset))]
 #![feature(asm)]
 #![feature(box_syntax)]
 #![feature(cfg_target_has_atomic)]

src/libstd/sys_common/memchr.rs

@@ -15,7 +15,6 @@
 pub mod fallback {
     use cmp;
     use mem;
-    use intrinsics::align_offset;
 
     const LO_U64: u64 = 0x0101010101010101;
     const HI_U64: u64 = 0x8080808080808080;
@@ -66,7 +65,7 @@ pub mod fallback {
         let usize_bytes = mem::size_of::<usize>();
 
         // search up to an aligned boundary
-        let mut offset = unsafe { align_offset(ptr as *const _, usize_bytes) };
+        let mut offset = ptr.align_offset(usize_bytes);
         if offset > 0 {
             offset = cmp::min(offset, len);
             if let Some(index) = text[..offset].iter().position(|elt| *elt == x) {