better code for a copy loop

R=rsc
https://golang.org/cl/152046

diff --git a/src/pkg/container/vector/vector.go b/src/pkg/container/vector/vector.go
index 714312be487771496eb2c7f6a98fbb0bf916c1cd..0a4db3b1f9849426a17452a22f545ec957190b50 100644 (file)
--- a/src/pkg/container/vector/vector.go
+++ b/src/pkg/container/vector/vector.go
@@ -19,8 +19,8 @@ type Vector struct {
 
 
 func copy(dst, src []Element) {
-       for i := 0; i < len(src); i++ {
-               dst[i] = src[i]
+       for i, x := range src {
+               dst[i] = x
        }
 }