---

yaml
---
r: 2197
b: refs/heads/master
c: 9edaa7d
h: refs/heads/master
i:
  2195: a326e0c
v: v3

Author: pcwalton

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9ab9bd9cc2dc97c2acc26849dd24b8989b76ea32
+refs/heads/master: 9edaa7dba3181ae68c60204e1e47a2d20e86236e

trunk/src/comp/middle/ty.rs

@@ -2362,9 +2362,15 @@ mod Unify {
 
         auto ures = unify_step(cx, expected, actual);
         alt (ures) {
-        case (ures_ok(?t)) {
+        case (ures_ok(?typ)) {
+            // Fast path: if there are no local variables, don't perform
+            // substitutions.
+            if (_vec.len[mutable UFind.node](cx.sets.nodes) == 0u) {
+                ret ures_ok(typ);
+            }
+
             auto set_types = unify_sets(cx);
-            auto t2 = substitute(cx, set_types, t);
+            auto t2 = substitute(cx, set_types, typ);
             ret ures_ok(t2);
         }
         case (_) { ret ures; }