Merge branch '0.4' of https://github.com/bluss/arrayvec

* '0.4' of https://github.com/bluss/arrayvec:
  0.4.10
  FIX: Remove unused Copy/Clone for MaybeUninit
  FIX: Use repr(C) MaybeUninit after discussion with RalfJung

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "arrayvec"
-version = "0.4.9"
+version = "0.4.10"
 authors = ["bluss"]
 license = "MIT/Apache-2.0"
 

README.rst

@@ -22,6 +22,11 @@ __ https://docs.rs/arrayvec
 Recent Changes (arrayvec)
 -------------------------
 
+- 0.4.10
+
+  - Use ``repr(C)`` in the ``union`` version that was introduced in 0.4.9, to
+    allay some soundness concerns.
+
 - 0.4.9
 
   - Use ``union`` in the implementation on when this is detected to be supported

src/maybe_uninit.rs

@@ -6,18 +6,13 @@ use std::mem::ManuallyDrop;
 /// A combination of ManuallyDrop and “maybe uninitialized”;
 /// this wraps a value that can be wholly or partially uninitialized;
 /// it also has no drop regardless of the type of T.
-#[derive(Copy)]
+#[repr(C)] // for cast from self ptr to value
 pub union MaybeUninit<T> {
     empty: (),
     value: ManuallyDrop<T>,
 }
 // Why we don't use std's MaybeUninit on nightly? See the ptr method
 
-impl<T> Clone for MaybeUninit<T> where T: Copy
-{
-    fn clone(&self) -> Self { *self }
-}
-
 impl<T> MaybeUninit<T> {
     /// Create a new MaybeUninit with uninitialized interior
     pub unsafe fn uninitialized() -> Self {