From 3298300ddf45a0792b4d8ea5e05f0fbceec4c9f9 Mon Sep 17 00:00:00 2001
From: Meng Zhuo <mengzhuo1203@gmail.com>
Date: Thu, 10 Dec 2020 09:52:52 +0800
Subject: text/template: error on range over send channel
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template range require channel contains RecvDir
if recv on send only channel will raise an panic.

Fixes #43065

Change-Id: Ie0ea70ce60e074bf8c9f2378e07ef1d4c41dc38f
Reviewed-on: https://go-review.googlesource.com/c/go/+/276532
Trust: Meng Zhuo <mzh@golangcn.org>
Run-TryBot: Meng Zhuo <mzh@golangcn.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
---
 src/text/template/exec.go | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'src/text/template/exec.go')

diff --git a/src/text/template/exec.go b/src/text/template/exec.go
index 7ac5175006..19154fc640 100644
--- a/src/text/template/exec.go
+++ b/src/text/template/exec.go
@@ -373,6 +373,10 @@ func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) {
 		if val.IsNil() {
 			break
 		}
+		if val.Type().ChanDir() == reflect.SendDir {
+			s.errorf("range over send-only channel %v", val)
+			break
+		}
 		i := 0
 		for ; ; i++ {
 			elem, ok := val.Recv()
-- 
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