From 9bbfd681c9fa47f462a89e8f5eedd3fa2a5de2e7 Mon Sep 17 00:00:00 2001
From: James Miller <james@aatch.net>
Date: Wed, 21 Jan 2015 09:35:24 +1300
Subject: [PATCH] Add assumptions that the pointer is non-null

---
 src/liballoc/rc.rs | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 0f2a11cc1dba..837d709e8820 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -933,12 +933,26 @@ fn weak(&self) -> uint { self.inner().weak.get() }
 
 impl<T> RcBoxPtr<T> for Rc<T> {
     #[inline(always)]
-    fn inner(&self) -> &RcBox<T> { unsafe { &(**self._ptr) } }
+    fn inner(&self) -> &RcBox<T> {
+        unsafe {
+            // Safe to assume this here, as if it weren't true, we'd be breaking
+            // the contract anyway
+            assume(!self._ptr.is_null());
+            &(**self._ptr)
+        }
+    }
 }
 
 impl<T> RcBoxPtr<T> for Weak<T> {
     #[inline(always)]
-    fn inner(&self) -> &RcBox<T> { unsafe { &(**self._ptr) } }
+    fn inner(&self) -> &RcBox<T> {
+        unsafe {
+            // Safe to assume this here, as if it weren't true, we'd be breaking
+            // the contract anyway
+            assume(!self._ptr.is_null());
+            &(**self._ptr)
+        }
+    }
 }
 
 #[cfg(test)]