go:linkname的用法

// src/os/proc.go 68行
func runtime_beforeExit() // implemented in runtime

// os_beforeExit is called from os.Exit(0).
//go:linkname os_beforeExit os.runtime_beforeExit
func os_beforeExit() {
    if raceenabled {
        racefini()
    }
}

$mkdir demo && cd demo

$go mod init demo

$mkdir hello
$mkdir link

$cd hello
// 函数签名
$vim hello.go
package hello

import (
    _ "demo/link"
)

func Hello()

// 函数体
$vim link.go
package link

import _ "unsafe"

//go:linkname helloWorld demo/hello.Hello
func helloWorld() {
    println("hello world!")
}

$cd demo
vim demo.go
package main

import (
    "demo/hello"
)

func main() {
    hello.Hello()
}

go run demo.go
# demo/hello
hello/hello.go:7:6: missing function body

$go run demo.go
hello world!