When running foo.go on windows 8 64 bits it panics.

foo.c

#include "foo.h"

void bar(process_handle_t handle, bool *b, memory_region_t *region) {
    region->start_address = 100;
    *b = true;
}

void open_process(process_handle_t *handle) {
    *handle = 0x201;
}

foo.go

package main

// #include "foo.h"
// #cgo CFLAGS: -std=c99
import "C"

import "runtime"
import "fmt"

type process struct {
	handle C.process_handle_t
	pid    int
}

func main() {
	var b int = 3
	var p process
	C.open_process(&(p.handle))
	foo(p, b)
}

func foo(p process, a int) {
	fmt.Println(a)
	var isAvailable C.bool
	var region C.memory_region_t

	runtime.GC()
	//fmt.Println(isAvailable, region)
	C.bar(p.handle, &isAvailable, &region)
}

foo.h

#ifndef __FOO__
#define __FOO__

#include <windows.h>
#include <stdbool.h>
#include <stdlib.h>

typedef unsigned long long memory_address_t;
typedef HANDLE process_handle_t;

typedef struct {
    memory_address_t start_address;
    size_t length;
} memory_region_t;

void bar(process_handle_t handle, bool *b, memory_region_t *region);
void open_process(process_handle_t *handle);

#endif // __FOO__