---

yaml
---
r: 174775
b: refs/heads/snap-stage3
c: a7525bc
h: refs/heads/master
i:
  174773: f050381
  174771: 93bd3ac
  174767: 80abcb5
v: v3

Author: Aatch

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: a0f86de49748b472d4d189d9688b0d856c000914
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 9bbfd681c9fa47f462a89e8f5eedd3fa2a5de2e7
+refs/heads/snap-stage3: a7525bc4c8eb8507a5c248d29286e77133217cf3
 refs/heads/try: 08f6380a9f0b866796080094f44fe25ea5636547
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d

branches/snap-stage3/src/liballoc/rc.rs

@@ -909,6 +909,8 @@ trait RcBoxPtr<T> {
     fn inc_strong(&self) {
         let strong = self.strong();
         // The reference count is always at least one unless we're about to drop the type
+        // This allows the bulk of the destructor to be omitted in cases where we know that
+        // the reference count must be > 0.
         unsafe { assume(strong > 0); }
         self.inner().strong.set(strong + 1);
     }
@@ -917,6 +919,8 @@ trait RcBoxPtr<T> {
     fn dec_strong(&self) {
         let strong = self.strong();
         // The reference count is always at least one unless we're about to drop the type
+        // This allows the bulk of the destructor to be omitted in cases where we know that
+        // the reference count must be > 0
         unsafe { assume(strong > 0); }
         self.inner().strong.set(strong - 1);
     }
@@ -936,7 +940,9 @@ impl<T> RcBoxPtr<T> for Rc<T> {
     fn inner(&self) -> &RcBox<T> {
         unsafe {
             // Safe to assume this here, as if it weren't true, we'd be breaking
-            // the contract anyway
+            // the contract anyway.
+            // This allows the null check to be elided in the destructor if we
+            // manipulated the reference count in the same function.
             assume(!self._ptr.is_null());
             &(**self._ptr)
         }
@@ -949,6 +955,8 @@ impl<T> RcBoxPtr<T> for Weak<T> {
         unsafe {
             // Safe to assume this here, as if it weren't true, we'd be breaking
             // the contract anyway
+            // This allows the null check to be elided in the destructor if we
+            // manipulated the reference count in the same function.
             assume(!self._ptr.is_null());
             &(**self._ptr)
         }