From 2f03857017ce9a6fa619c4747039f72eeaea002a Mon Sep 17 00:00:00 2001
From: Benjamin Saunders <ben.e.saunders@gmail.com>
Date: Mon, 24 Sep 2018 18:04:57 -0700
Subject: [PATCH] Introduce Unit::from_ref_unchecked

---
 src/base/unit.rs | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/base/unit.rs b/src/base/unit.rs
index b49bc83c..2b466c04 100644
--- a/src/base/unit.rs
+++ b/src/base/unit.rs
@@ -16,7 +16,7 @@ use alga::linear::NormedSpace;
 /// A wrapper that ensures the underlying algebraic entity has a unit norm.
 ///
 /// Use `.as_ref()` or `.unwrap()` to obtain the underlying value by-reference or by-move.
-#[repr(C)]
+#[repr(transparent)]
 #[derive(Eq, PartialEq, Clone, Hash, Debug, Copy)]
 pub struct Unit<T> {
     value: T,
@@ -104,13 +104,17 @@ impl<T: NormedSpace> Unit<T> {
 
 impl<T> Unit<T> {
     /// Wraps the given value, assuming it is already normalized.
-    ///
-    /// This function is not safe because `value` is not verified to be actually normalized.
     #[inline]
     pub fn new_unchecked(value: T) -> Self {
         Unit { value: value }
     }
 
+    /// Wraps the given reference, assuming it is already normalized.
+    #[inline]
+    pub fn from_ref_unchecked<'a>(value: &'a T) -> &'a Self {
+        unsafe { mem::transmute(value) }
+    }
+
     /// Retrieves the underlying value.
     #[inline]
     pub fn unwrap(self) -> T {