cfunc.c

void ACFunction() {
  printf("ACFunction()\n");
  AGoFunction();
}

cfunc.h

void ACFunction();
extern void AGoFunction();

error.txt

# command-line-arguments
Undefined symbols for architecture x86_64:
  "_ACFunction", referenced from:
      __cgo_4032a8ce2271_Cfunc_ACFunction in wiki.cgo2.o
     (maybe you meant: __cgo_4032a8ce2271_Cfunc_ACFunction)
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status

wiki.go

package main

import "fmt"

/*
#include <stdio.h>
#include "cfunc.h"
*/
import "C"

//export AGoFunction
func AGoFunction() {
  fmt.Println("AGoFunction()")
}

func Example() {
  C.ACFunction()
}

func main() {
  fmt.Println("starting")
  Example()
  fmt.Println("ending")
}