---

yaml
---
r: 12189
b: refs/heads/master
c: b7b66b6
h: refs/heads/master
i:
  12187: e1265a6
v: v3

Author: brson

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: c0a99790cb5cf3ba54954b1b8f7c04f54c42f984
+refs/heads/master: b7b66b6cb3aa7b04d611f22d9d0029945e539db1
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 4a81779abd786ff22d71434c6d9a5917ea4cdfff
 refs/heads/try: 2898dcc5d97da9427ac367542382b6239d9c0bbf

trunk/src/libcore/str.rs

@@ -1504,7 +1504,9 @@ capacity, then no action is taken.
 * n - The number of bytes to reserve space for
 "]
 fn reserve(&s: str, n: uint) {
-    rustrt::str_reserve_shared(s, n);
+    if capacity(s) < n {
+        rustrt::str_reserve_shared(s, n);
+    }
 }
 
 #[doc = "

trunk/src/libcore/vec.rs

@@ -113,7 +113,10 @@ capacity, then no action is taken.
 * n - The number of elements to reserve space for
 "]
 fn reserve<T>(&v: [const T], n: uint) {
-    rustrt::vec_reserve_shared(sys::get_type_desc::<T>(), v, n);
+    // Only make the (slow) call into the runtime if we have to
+    if capacity(v) < n {
+        rustrt::vec_reserve_shared(sys::get_type_desc::<T>(), v, n);
+    }
 }
 
 #[doc = "