auto merge of #18368 : alexcrichton/rust/rollup, r=alexcrichton

3 files changed, 27 insertions, 7 deletions

diff --git a/src/libstd/ascii.rs b/src/libstd/ascii.rs
index 07be15486fd..c2e88bfdbcf 100644
--- a/src/libstd/ascii.rs
+++ b/src/libstd/ascii.rs
@@ -247,8 +247,7 @@ impl OwnedAsciiCast for String {
 
     #[inline]
     unsafe fn into_ascii_nocheck(self) -> Vec<Ascii> {
-        let v: Vec<u8> = mem::transmute(self);
-        v.into_ascii_nocheck()
+        self.into_bytes().into_ascii_nocheck()
     }
 }
 
@@ -260,7 +259,14 @@ impl OwnedAsciiCast for Vec<u8> {
 
     #[inline]
     unsafe fn into_ascii_nocheck(self) -> Vec<Ascii> {
-        mem::transmute(self)
+        let v = Vec::from_raw_parts(self.as_ptr() as *mut Ascii,
+                                    self.len(),
+                                    self.capacity());
+
+        // We forget `self` to avoid freeing it at the end of the scope
+        // Otherwise, the returned `Vec` would point to freed memory
+        mem::forget(self);
+        v
     }
 }
 
@@ -338,7 +344,16 @@ pub trait IntoBytes {
 
 impl IntoBytes for Vec<Ascii> {
     fn into_bytes(self) -> Vec<u8> {
-        unsafe { mem::transmute(self) }
+        unsafe {
+            let v = Vec::from_raw_parts(self.as_ptr() as *mut u8,
+                                        self.len(),
+                                        self.capacity());
+
+            // We forget `self` to avoid freeing it at the end of the scope
+            // Otherwise, the returned `Vec` would point to freed memory
+            mem::forget(self);
+            v
+        }
     }
 }
 
diff --git a/src/libstd/collections/hashmap/set.rs b/src/libstd/collections/hashmap/set.rs
index dde1f27c9a3..ca954679c1c 100644
--- a/src/libstd/collections/hashmap/set.rs
+++ b/src/libstd/collections/hashmap/set.rs
@@ -186,7 +186,7 @@ impl<T: Eq + Hash<S>, S, H: Hasher<S>> HashSet<T, H> {
     /// # Example
     ///
     /// This is a slightly silly example where we define the number's
-    /// parity as the equivilance class. It is important that the
+    /// parity as the equivalance class. It is important that the
     /// values hash the same, which is why we implement `Hash`.
     ///
     /// ```
diff --git a/src/libstd/io/mem.rs b/src/libstd/io/mem.rs
index f86ae05d623..dd4a3e05935 100644
--- a/src/libstd/io/mem.rs
+++ b/src/libstd/io/mem.rs
@@ -22,7 +22,7 @@ use slice;
 use slice::AsSlice;
 use vec::Vec;
 
-static BUF_CAPACITY: uint = 128;
+const BUF_CAPACITY: uint = 128;
 
 fn combine(seek: SeekStyle, cur: uint, end: uint, offset: i64) -> IoResult<u64> {
     // compute offset as signed and clamp to prevent overflow
@@ -71,7 +71,12 @@ impl MemWriter {
     /// the internal buffer.
     #[inline]
     pub fn with_capacity(n: uint) -> MemWriter {
-        MemWriter { buf: Vec::with_capacity(n) }
+        MemWriter::from_vec(Vec::with_capacity(n))
+    }
+    /// Create a new `MemWriter` that will append to an existing `Vec`.
+    #[inline]
+    pub fn from_vec(buf: Vec<u8>) -> MemWriter {
+        MemWriter { buf: buf }
     }
 
     /// Acquires an immutable reference to the underlying buffer of this