From f8376a55b06304bd24612d10812cf8ada29a5c84 Mon Sep 17 00:00:00 2001
From: Dmitri Shuralyov <dmitshur@golang.org>
Date: Fri, 23 Oct 2020 03:46:19 +0000
Subject: [PATCH] sync: document that Once must not be copied

Fixes #42160.

Change-Id: I9bf8b6f0bf1eccd3ab32cbd94c812f768746d291
Reviewed-on: https://go-review.googlesource.com/c/go/+/264557
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
---
 src/sync/once.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/sync/once.go b/src/sync/once.go
index ca04408224..bf4b80c867 100644
--- a/src/sync/once.go
+++ b/src/sync/once.go
@@ -9,6 +9,8 @@ import (
 )
 
 // Once is an object that will perform exactly one action.
+//
+// A Once must not be copied after first use.
 type Once struct {
 	// done indicates whether the action has been performed.
 	// It is first in the struct because it is used in the hot path.
-- 
2.50.0