---

yaml
---
r: 195447
b: refs/heads/master
c: 7afc7d3
h: refs/heads/master
i:
  195445: 2f319f7
  195443: aa218a8
  195439: 0a3c4e4
v: v3

Author: Manishearth

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: 1026b064429f81ed5358abf501098e3aef21d07d
+refs/heads/master: 7afc7d3e3566c1e1f8b770cf34ec7e50e045eb69
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: b3317d68910900f135f9f38e43a7a699bc736b4a
 refs/heads/try: 961e0358e1a5c0faaef606e31e9965742c1643bf

trunk/src/doc/reference.md

@@ -1188,12 +1188,15 @@ the guarantee that these issues are never caused by safe code.
 
 * Data races
 * Dereferencing a null/dangling raw pointer
-* Mutating an immutable value/reference without `UnsafeCell`
 * Reads of [undef](http://llvm.org/docs/LangRef.html#undefined-values)
   (uninitialized) memory
 * Breaking the [pointer aliasing
   rules](http://llvm.org/docs/LangRef.html#pointer-aliasing-rules)
   with raw pointers (a subset of the rules used by C)
+* `&mut` and `&` follow LLVM’s scoped [noalias] model, except if the `&T`
+  contains an `UnsafeCell<U>`. Unsafe code must not violate these aliasing
+  guarantees.
+* Mutating an immutable value/reference without `UnsafeCell<U>`
 * Invoking undefined behavior via compiler intrinsics:
   * Indexing outside of the bounds of an object with `std::ptr::offset`
     (`offset` intrinsic), with
@@ -1210,6 +1213,8 @@ the guarantee that these issues are never caused by safe code.
   code. Rust's failure system is not compatible with exception handling in
   other languages. Unwinding must be caught and handled at FFI boundaries.
 
+[noalias]: http://llvm.org/docs/LangRef.html#noalias
+
 ##### Behaviour not considered unsafe
 
 This is a list of behaviour not considered *unsafe* in Rust terms, but that may

trunk/src/doc/trpl/ownership.md

@@ -472,10 +472,15 @@ thread-safe counterpart of `Rc<T>`.
 
 ## Lifetime Elision
 
-Earlier, we mentioned *lifetime elision*, a feature of Rust which allows you to
-not write lifetime annotations in certain circumstances. All references have a
-lifetime, and so if you elide a lifetime (like `&T` instead of `&'a T`), Rust
-will do three things to determine what those lifetimes should be.
+Rust supports powerful local type inference in function bodies, but it’s
+forbidden in item signatures to allow reasoning about the types just based in
+the item signature alone. However, for ergonomic reasons a very restricted
+secondary inference algorithm called “lifetime elision” applies in function
+signatures. It infers only based on the signature components themselves and not
+based on the body of the function, only infers lifetime paramters, and does
+this with only three easily memorizable and unambiguous rules. This makes
+lifetime elision a shorthand for writing an item signature, while not hiding
+away the actual types involved as full local inference would if applied to it.
 
 When talking about lifetime elision, we use the term *input lifetime* and
 *output lifetime*. An *input lifetime* is a lifetime associated with a parameter

trunk/src/doc/trpl/testing.md

@@ -231,7 +231,7 @@ pub fn add_two(a: i32) -> i32 {
 }
 
 #[cfg(test)]
-mod tests {
+mod test {
     use super::add_two;
 
     #[test]
@@ -241,7 +241,7 @@ mod tests {
 }
 ```
 
-There's a few changes here. The first is the introduction of a `mod tests` with
+There's a few changes here. The first is the introduction of a `mod test` with
 a `cfg` attribute. The module allows us to group all of our tests together, and
 to also define helper functions if needed, that don't become a part of the rest
 of our crate. The `cfg` attribute only compiles our test code if we're
@@ -260,7 +260,7 @@ pub fn add_two(a: i32) -> i32 {
 }
 
 #[cfg(test)]
-mod tests {
+mod test {
     use super::*;
 
     #[test]

trunk/src/liballoc/heap.rs

@@ -301,7 +301,7 @@ mod imp {
             libc::realloc(ptr as *mut libc::c_void, size as libc::size_t) as *mut u8
         } else {
             let new_ptr = allocate(size, align);
-            ptr::copy(new_ptr, ptr, cmp::min(size, old_size));
+            ptr::copy(ptr, new_ptr, cmp::min(size, old_size));
             deallocate(ptr, old_size, align);
             new_ptr
         }

trunk/src/libcollections/btree/node.rs

@@ -1133,13 +1133,13 @@ impl<K, V> Node<K, V> {
     #[inline]
     unsafe fn insert_kv(&mut self, index: usize, key: K, val: V) -> &mut V {
         ptr::copy(
-            self.keys_mut().as_mut_ptr().offset(index as isize + 1),
             self.keys().as_ptr().offset(index as isize),
+            self.keys_mut().as_mut_ptr().offset(index as isize + 1),
             self.len() - index
         );
         ptr::copy(
-            self.vals_mut().as_mut_ptr().offset(index as isize + 1),
             self.vals().as_ptr().offset(index as isize),
+            self.vals_mut().as_mut_ptr().offset(index as isize + 1),
             self.len() - index
         );
 
@@ -1155,8 +1155,8 @@ impl<K, V> Node<K, V> {
     #[inline]
     unsafe fn insert_edge(&mut self, index: usize, edge: Node<K, V>) {
         ptr::copy(
-            self.edges_mut().as_mut_ptr().offset(index as isize + 1),
             self.edges().as_ptr().offset(index as isize),
+            self.edges_mut().as_mut_ptr().offset(index as isize + 1),
             self.len() - index
         );
         ptr::write(self.edges_mut().get_unchecked_mut(index), edge);
@@ -1188,13 +1188,13 @@ impl<K, V> Node<K, V> {
         let val = ptr::read(self.vals().get_unchecked(index));
 
         ptr::copy(
-            self.keys_mut().as_mut_ptr().offset(index as isize),
             self.keys().as_ptr().offset(index as isize + 1),
+            self.keys_mut().as_mut_ptr().offset(index as isize),
             self.len() - index - 1
         );
         ptr::copy(
-            self.vals_mut().as_mut_ptr().offset(index as isize),
             self.vals().as_ptr().offset(index as isize + 1),
+            self.vals_mut().as_mut_ptr().offset(index as isize),
             self.len() - index - 1
         );
 
@@ -1209,8 +1209,8 @@ impl<K, V> Node<K, V> {
         let edge = ptr::read(self.edges().get_unchecked(index));
 
         ptr::copy(
-            self.edges_mut().as_mut_ptr().offset(index as isize),
             self.edges().as_ptr().offset(index as isize + 1),
+            self.edges_mut().as_mut_ptr().offset(index as isize),
             // index can be == len+1, so do the +1 first to avoid underflow.
             (self.len() + 1) - index
         );
@@ -1237,19 +1237,19 @@ impl<K, V> Node<K, V> {
             right._len = self.len() / 2;
             let right_offset = self.len() - right.len();
             ptr::copy_nonoverlapping(
-                right.keys_mut().as_mut_ptr(),
                 self.keys().as_ptr().offset(right_offset as isize),
+                right.keys_mut().as_mut_ptr(),
                 right.len()
             );
             ptr::copy_nonoverlapping(
-                right.vals_mut().as_mut_ptr(),
                 self.vals().as_ptr().offset(right_offset as isize),
+                right.vals_mut().as_mut_ptr(),
                 right.len()
             );
             if !self.is_leaf() {
                 ptr::copy_nonoverlapping(
-                    right.edges_mut().as_mut_ptr(),
                     self.edges().as_ptr().offset(right_offset as isize),
+                    right.edges_mut().as_mut_ptr(),
                     right.len() + 1
                 );
             }
@@ -1278,19 +1278,19 @@ impl<K, V> Node<K, V> {
             ptr::write(self.vals_mut().get_unchecked_mut(old_len), val);
 
             ptr::copy_nonoverlapping(
-                self.keys_mut().as_mut_ptr().offset(old_len as isize + 1),
                 right.keys().as_ptr(),
+                self.keys_mut().as_mut_ptr().offset(old_len as isize + 1),
                 right.len()
             );
             ptr::copy_nonoverlapping(
-                self.vals_mut().as_mut_ptr().offset(old_len as isize + 1),
                 right.vals().as_ptr(),
+                self.vals_mut().as_mut_ptr().offset(old_len as isize + 1),
                 right.len()
             );
             if !self.is_leaf() {
                 ptr::copy_nonoverlapping(
-                    self.edges_mut().as_mut_ptr().offset(old_len as isize + 1),
                     right.edges().as_ptr(),
+                    self.edges_mut().as_mut_ptr().offset(old_len as isize + 1),
                     right.len() + 1
                 );
             }

trunk/src/libcollections/slice.rs

@@ -1320,10 +1320,10 @@ fn insertion_sort<T, F>(v: &mut [T], mut compare: F) where F: FnMut(&T, &T) -> O
 
             if i != j {
                 let tmp = ptr::read(read_ptr);
-                ptr::copy(buf_v.offset(j + 1),
-                          &*buf_v.offset(j),
+                ptr::copy(&*buf_v.offset(j),
+                          buf_v.offset(j + 1),
                           (i - j) as usize);
-                ptr::copy_nonoverlapping(buf_v.offset(j), &tmp, 1);
+                ptr::copy_nonoverlapping(&tmp, buf_v.offset(j), 1);
                 mem::forget(tmp);
             }
         }
@@ -1396,10 +1396,10 @@ fn merge_sort<T, F>(v: &mut [T], mut compare: F) where F: FnMut(&T, &T) -> Order
                 // j + 1 could be `len` (for the last `i`), but in
                 // that case, `i == j` so we don't copy. The
                 // `.offset(j)` is always in bounds.
-                ptr::copy(buf_dat.offset(j + 1),
-                          &*buf_dat.offset(j),
+                ptr::copy(&*buf_dat.offset(j),
+                          buf_dat.offset(j + 1),
                           i - j as usize);
-                ptr::copy_nonoverlapping(buf_dat.offset(j), read_ptr, 1);
+                ptr::copy_nonoverlapping(read_ptr, buf_dat.offset(j), 1);
             }
         }
     }
@@ -1447,11 +1447,11 @@ fn merge_sort<T, F>(v: &mut [T], mut compare: F) where F: FnMut(&T, &T) -> Order
                     if left == right_start {
                         // the number remaining in this run.
                         let elems = (right_end as usize - right as usize) / mem::size_of::<T>();
-                        ptr::copy_nonoverlapping(out, &*right, elems);
+                        ptr::copy_nonoverlapping(&*right, out, elems);
                         break;
                     } else if right == right_end {
                         let elems = (right_start as usize - left as usize) / mem::size_of::<T>();
-                        ptr::copy_nonoverlapping(out, &*left, elems);
+                        ptr::copy_nonoverlapping(&*left, out, elems);
                         break;
                     }
 
@@ -1465,7 +1465,7 @@ fn merge_sort<T, F>(v: &mut [T], mut compare: F) where F: FnMut(&T, &T) -> Order
                     } else {
                         step(&mut left)
                     };
-                    ptr::copy_nonoverlapping(out, &*to_copy, 1);
+                    ptr::copy_nonoverlapping(&*to_copy, out, 1);
                     step(&mut out);
                 }
             }
@@ -1479,7 +1479,7 @@ fn merge_sort<T, F>(v: &mut [T], mut compare: F) where F: FnMut(&T, &T) -> Order
     // write the result to `v` in one go, so that there are never two copies
     // of the same object in `v`.
     unsafe {
-        ptr::copy_nonoverlapping(v.as_mut_ptr(), &*buf_dat, len);
+        ptr::copy_nonoverlapping(&*buf_dat, v.as_mut_ptr(), len);
     }
 
     // increment the pointer, returning the old pointer.

trunk/src/libcollections/string.rs

@@ -592,8 +592,8 @@ impl String {
         let ch = self.char_at(idx);
         let next = idx + ch.len_utf8();
         unsafe {
-            ptr::copy(self.vec.as_mut_ptr().offset(idx as isize),
-                      self.vec.as_ptr().offset(next as isize),
+            ptr::copy(self.vec.as_ptr().offset(next as isize),
+                      self.vec.as_mut_ptr().offset(idx as isize),
                       len - next);
             self.vec.set_len(len - (next - idx));
         }
@@ -622,11 +622,11 @@ impl String {
         let amt = ch.encode_utf8(&mut bits).unwrap();
 
         unsafe {
-            ptr::copy(self.vec.as_mut_ptr().offset((idx + amt) as isize),
-                      self.vec.as_ptr().offset(idx as isize),
+            ptr::copy(self.vec.as_ptr().offset(idx as isize),
+                      self.vec.as_mut_ptr().offset((idx + amt) as isize),
                       len - idx);
-            ptr::copy(self.vec.as_mut_ptr().offset(idx as isize),
-                      bits.as_ptr(),
+            ptr::copy(bits.as_ptr(),
+                      self.vec.as_mut_ptr().offset(idx as isize),
                       amt);
             self.vec.set_len(len + amt);
         }
@@ -1019,27 +1019,44 @@ impl AsRef<str> for String {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> From<&'a str> for String {
+    #[inline]
     fn from(s: &'a str) -> String {
         s.to_string()
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a> From<&'a str> for Cow<'a, str> {
+    #[inline]
+    fn from(s: &'a str) -> Cow<'a, str> {
+        Cow::Borrowed(s)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a> From<String> for Cow<'a, str> {
+    #[inline]
+    fn from(s: String) -> Cow<'a, str> {
+        Cow::Owned(s)
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl Into<Vec<u8>> for String {
     fn into(self) -> Vec<u8> {
         self.into_bytes()
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
+#[unstable(feature = "into_cow", reason = "may be replaced by `convert::Into`")]
 impl IntoCow<'static, str> for String {
     #[inline]
     fn into_cow(self) -> Cow<'static, str> {
         Cow::Owned(self)
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
+#[unstable(feature = "into_cow", reason = "may be replaced by `convert::Into`")]
 impl<'a> IntoCow<'a, str> for &'a str {
     #[inline]
     fn into_cow(self) -> Cow<'a, str> {

trunk/src/libcollections/vec.rs

@@ -260,16 +260,17 @@ impl<T> Vec<T> {
 
     /// Creates a vector by copying the elements from a raw pointer.
     ///
-    /// This function will copy `elts` contiguous elements starting at `ptr` into a new allocation
-    /// owned by the returned `Vec<T>`. The elements of the buffer are copied into the vector
-    /// without cloning, as if `ptr::read()` were called on them.
+    /// This function will copy `elts` contiguous elements starting at `ptr`
+    /// into a new allocation owned by the returned `Vec<T>`. The elements of
+    /// the buffer are copied into the vector without cloning, as if
+    /// `ptr::read()` were called on them.
     #[inline]
     #[unstable(feature = "collections",
                reason = "may be better expressed via composition")]
     pub unsafe fn from_raw_buf(ptr: *const T, elts: usize) -> Vec<T> {
         let mut dst = Vec::with_capacity(elts);
         dst.set_len(elts);
-        ptr::copy_nonoverlapping(dst.as_mut_ptr(), ptr, elts);
+        ptr::copy_nonoverlapping(ptr, dst.as_mut_ptr(), elts);
         dst
     }
 
@@ -288,8 +289,9 @@ impl<T> Vec<T> {
         self.cap
     }
 
-    /// Reserves capacity for at least `additional` more elements to be inserted in the given
-    /// `Vec<T>`. The collection may reserve more space to avoid frequent reallocations.
+    /// Reserves capacity for at least `additional` more elements to be inserted
+    /// in the given `Vec<T>`. The collection may reserve more space to avoid
+    /// frequent reallocations.
     ///
     /// # Panics
     ///
@@ -541,7 +543,7 @@ impl<T> Vec<T> {
                 let p = self.as_mut_ptr().offset(index as isize);
                 // Shift everything over to make space. (Duplicating the
                 // `index`th element into two consecutive places.)
-                ptr::copy(p.offset(1), &*p, len - index);
+                ptr::copy(&*p, p.offset(1), len - index);
                 // Write it in, overwriting the first copy of the `index`th
                 // element.
                 ptr::write(&mut *p, element);
@@ -579,7 +581,7 @@ impl<T> Vec<T> {
                 ret = ptr::read(ptr);
 
                 // Shift everything down to fill in that spot.
-                ptr::copy(ptr, &*ptr.offset(1), len - index - 1);
+                ptr::copy(&*ptr.offset(1), ptr, len - index - 1);
             }
             self.set_len(len - 1);
             ret
@@ -721,8 +723,8 @@ impl<T> Vec<T> {
         let len = self.len();
         unsafe {
             ptr::copy_nonoverlapping(
-                self.get_unchecked_mut(len),
                 other.as_ptr(),
+                self.get_unchecked_mut(len),
                 other.len());
         }
 
@@ -1042,8 +1044,8 @@ impl<T> Vec<T> {
             other.set_len(other_len);
 
             ptr::copy_nonoverlapping(
-                other.as_mut_ptr(),
                 self.as_ptr().offset(at as isize),
+                other.as_mut_ptr(),
                 other.len());
         }
         other