From: Russ Cox <rsc@golang.org>
Date: Fri, 27 Jan 2012 21:11:17 +0000 (-0500)
Subject: reflect: add comment about Type.Field allocation
X-Git-Tag: weekly.2012-02-07~249
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=c4303aa59ff4c6ddb350a7d670e455426c16962b;p=gostls13.git

reflect: add comment about Type.Field allocation

R=golang-dev, bradfitz, r
CC=golang-dev
https://golang.org/cl/5586044
---

diff --git a/src/pkg/reflect/type.go b/src/pkg/reflect/type.go
index 15b32efe37..0acee9e434 100644
--- a/src/pkg/reflect/type.go
+++ b/src/pkg/reflect/type.go
@@ -789,6 +789,14 @@ func (t *structType) Field(i int) (f StructField) {
 		f.Tag = StructTag(*p.tag)
 	}
 	f.Offset = p.offset
+
+	// NOTE(rsc): This is the only allocation in the interface
+	// presented by a reflect.Type.  It would be nice to avoid,
+	// at least in the common cases, but we need to make sure
+	// that misbehaving clients of reflect cannot affect other
+	// uses of reflect.  One possibility is CL 5371098, but we
+	// postponed that ugliness until there is a demonstrated
+	// need for the performance.  This is issue 2320.
 	f.Index = []int{i}
 	return
 }