From 2dde4f5d2906eab25625f6a260a2eb80be9ce572 Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Thu, 24 May 2012 10:59:48 -0700
Subject: [PATCH] spec: clarify evaluation order of "i, x[i] = range ..."

Part of fix for issue 3464.

R=golang-dev, rsc, mirtchovski, iant, r
CC=golang-dev
https://golang.org/cl/6246045
---
 doc/go_spec.html | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/doc/go_spec.html b/doc/go_spec.html
index 8cb257a59fb..78197351f28 100644
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of March 17, 2012",
+	"Subtitle": "Version of May 24, 2012",
 	"Path": "/ref/spec"
 }-->
 
@@ -3866,7 +3866,11 @@ x, _ = f()  // ignore second value returned by f()
 In the second form, the number of operands on the left must equal the number
 of expressions on the right, each of which must be single-valued, and the
 <i>n</i>th expression on the right is assigned to the <i>n</i>th
-operand on the left.  The assignment proceeds in two phases.
+operand on the left.
+</p>
+
+<p>
+The assignment proceeds in two phases.
 First, the operands of <a href="#Indexes">index expressions</a>
 and <a href="#Address_operators">pointer indirections</a>
 (including implicit pointer indirections in <a href="#Selectors">selectors</a>)
@@ -3885,13 +3889,20 @@ i, x[i] = 1, 2  // set i = 1, x[0] = 2
 i = 0
 x[i], i = 2, 1  // set x[0] = 2, i = 1
 
-x[0], x[0] = 1, 2  // set x[0] = 1, then x[0] = 2 (so x[0] = 2 at end)
+x[0], x[0] = 1, 2  // set x[0] = 1, then x[0] = 2 (so x[0] == 2 at end)
 
 x[1], x[3] = 4, 5  // set x[1] = 4, then panic setting x[3] = 5.
 
 type Point struct { x, y int }
 var p *Point
 x[2], p.x = 6, 7  // set x[2] = 6, then panic setting p.x = 7
+
+i = 2
+x = []int{3, 5, 7}
+for i, x[i] = range x {  // set i, x[2] = 0, x[0]
+	break
+}
+// after this loop, i == 0 and x == []int{3, 5, 3}
 </pre>
 
 <p>