From: Robert Griesemer <gri@golang.org>
Date: Wed, 27 Jan 2010 17:35:39 +0000 (-0800)
Subject: Clarify parsing of channel types.
X-Git-Tag: weekly.2010-01-27~14
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=1c369bd55fda993c2612452ec8e19dda2637106d;p=gostls13.git

Clarify parsing of channel types.

R=r, rsc
CC=golang-dev
https://golang.org/cl/194091
---

diff --git a/doc/go_spec.html b/doc/go_spec.html
index b5931c110e..3823876457 100644
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -1107,6 +1107,19 @@ SendChannel   = "chan" "&lt;-" ElementType .
 RecvChannel   = "&lt;-" "chan" ElementType .
 </pre>
 
+<p>
+To avoid a parsing ambiguity in cases such as <code>chan&lt;- chan int</code>,
+the Channel production's ElementType cannot be a RecvChannel.
+To construct such a type, parenthesize the RecvChannel first.
+</p>
+
+<pre>
+chan&lt;- chan int     // same as chan&lt;- (chan int)
+chan&lt;- &lt;-chan int   // same as chan&lt;- (&lt;-chan int)
+&lt;-chan &lt;-chan int   // same as &lt;-chan (&lt;-chan int)
+chan (&lt;-chan int)
+</pre>
+
 <p>
 Upon creation, a channel can be used both to send and to receive values.
 By conversion or assignment, a channel may be constrained only to send or
@@ -1126,7 +1139,6 @@ value can be made using the built-in function <code>make</code>,
 which takes the channel type and an optional capacity as arguments:
 </p>
 
-
 <pre>
 make(chan int, 100)
 </pre>