---

yaml
---
r: 32438
b: refs/heads/dist-snap
c: 3405c54
h: refs/heads/master
v: v3

Author: Elliott Slaughter

[refs]

@@ -7,6 +7,6 @@ refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
 refs/heads/try2: d0c6ce338884ee21843f4b40bf6bf18d222ce5df
 refs/heads/incoming: d9317a174e434d4c99fc1a37fd7dc0d2f5328d37
-refs/heads/dist-snap: 9ea4afe5daf359c7022057774f943645d0d32043
+refs/heads/dist-snap: 3405c548e8f65c9955dfc89188f3cd9db4432bba
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

branches/dist-snap/src/libcore/gc.rs

@@ -102,6 +102,12 @@ unsafe fn walk_gc_roots(mem: Memory, visitor: Visitor) {
                 match sp {
                   Some(sp_info) => {
                     for walk_safe_point(frame.fp, sp_info) |root, tydesc| {
+                        // Skip null pointers, which can occur when a
+                        // unique pointer has already been freed.
+                        if ptr::is_null(*root) {
+                            again;
+                        }
+
                         if ptr::is_null(tydesc) {
                             // Root is a generic box.
                             let refcount = **root;