在Golang包中编译CGO文件

Question

I am trying to use CGO to bundle C files with a Golang package. Following instructions here:

https://karthikkaranth.me/blog/calling-c-code-from-go/

http://akrennmair.github.io/golang-cgo-slides/#1

https://golang.org/cmd/cgo/

I am getting this error:

# main 
src/main/main.go:16:8: could not determine kind of name for C.free 
src/main/main.go:23:10: could not determine kind of name for C.greet

here is the structure:

main.go just looks like:

package main

// #cgo CFLAGS: -g -Wall
// #include <stdlib.h>
// #include "genericc/greeter.h"

import "C"

import (
    "fmt"
    "unsafe"
)

func main() {
    name := C.CString("Gopher")
    defer C.free(unsafe.Pointer(name))

    year := C.int(2018)

    ptr := C.malloc(C.sizeof_char * 1024)
    defer C.free(unsafe.Pointer(ptr))

    size := C.greet(name, year, (*C.char)(ptr))

    b := C.GoBytes(ptr, size)
    fmt.Println(string(b))
}

and I run test.sh to build it:

#!/usr/bin/env bash

dir="$(cd `dirname "$0"` && pwd)"
export GOPATH="$dir"

cd "$dir"

export CGOFILES=main
go install main

but when I run the bash script I get that error.