CGo C++ test

cmylib.cc

// mylib.c
#include "mylib.hh"
#include "cmylib.h"

Foo FooInit()
{
  cxxFoo * ret = new cxxFoo(1);
  return (void*)ret;
}
void FooFree(Foo f)
{
  cxxFoo * foo = (cxxFoo*)f;
  delete foo;
}
void FooBar(Foo f)
{
  cxxFoo * foo = (cxxFoo*)f;
  foo->Bar();
}

cmylib.h

// mylib.h
#ifdef __cplusplus
extern "C" {
#endif

typedef void* Foo;
Foo FooInit(void);
void FooFree(Foo);
void FooBar(Foo);

#ifdef __cplusplus
}
#endif

go.mod

module example.com/test

go 1.18

lib-mylib.cc

#include <iostream>

#include "mylib.hh"

void cxxFoo::Bar(void){ std::cout << "hello\n"; }

lib-mylib.hh

class cxxFoo {
public:
  int a;
  cxxFoo(int _a):a(_a){};
  ~cxxFoo(){};
  void Bar();
};

main.go

package main

// #cgo LDFLAGS: -Llib -lmylib_a
// #cgo CPPFLAGS: -Ilib
// #include "cmylib.h"
import "C"

import (
	"unsafe"
)

type GoFoo struct {
     foo C.Foo
}
func New() (GoFoo) {
     var ret GoFoo;
     ret.foo = C.FooInit()
     return ret
}
func (f GoFoo) Free(){
     C.FooFree(C.Foo(unsafe.Pointer(f.foo)))
}
func (f GoFoo) Bar(){
     C.FooBar(C.Foo(unsafe.Pointer(f.foo)))
}

func main() {
    mylib := New()
    mylib.Bar()
    mylib.Free()
}

running.txt

$ cd lib
lib$ g++ -c -o mylib.o mylib.cc 
lib$ ar -crs libmylib_a.a mylib.o
lib$ cd ..
$ go run .
hello