Question

匿名嵌入，可让 go vet 检查到复制行为。

// sync/cond.go

// noCopy may be embedded into structs which must not be copied
// after the first use.
//
// See https://golang.org/issues/8005#issuecomment-190753527
// for details.
type noCopy struct{}

// Lock is a no-op used by -copylocks checker from `go vet`.
func (*noCopy) Lock()   {}
func (*noCopy) Unlock() {}

实际检查 Lock, Unlock 两个方法，所以自己实现一个也是可以的。

package main

import (
	"fmt"
)

type noCopy struct{}

func (*noCopy) Lock()   {}
func (*noCopy) Unlock() {}

// -----------------------

type X struct {
	noCopy
	a int
}

func main() {
	var x X
	a := x
	fmt.Println(a, x)
}

/*

$ go vet

19: assignment copies lock value to a: X
20: call of fmt.Println copies lock value: X

*/