Use stdlib and rand with Node native module (node-gyp)

Question

This is just an example of the problem.

Let's say I have utils.cc

#include "../headers/utils/utils.h"

double sum()
{
    double result = 1 + 1;
    return result;
}

double multisum(int n)
{
    double result = 0;
    for (int i = 0; i < n; i++)
    {
        result += rand();
    }
    return result;
}

and this file that uses it

#include "../headers/modules/sum.h"
#include "../headers/utils.h"

/* HELPERS DECLARATION */

static void ReturnResult(int result, const FunctionCallbackInfo<Value> &args);

/* EXPORTED IMPLEMENTATION */

void Sum(const FunctionCallbackInfo<Value> &args)
{
    double result = sum();
    ReturnResult(result, args);
}
void Multisum1e7(const FunctionCallbackInfo<Value> &args)
{
    int result = multisum(1e7);
    ReturnResult(result, args);
}

/* HELPERS IMPLEMENTATION */

static void ReturnResult(double result, const FunctionCallbackInfo<Value> &args)
{
    Isolate *isolate = args.GetIsolate();
    args.GetReturnValue().Set(Number::New(isolate, result));
}

These functions are then exported with <node.h>.

The problem is in the rand() function. The code compiles (I have included stdlib in the code) and this is the binding.gyp:

{
  "targets": [
    {
      "target_name": "addon",
      "sources": [
        "addon/main.cc",
        "addon/utils.cc",
        "addon/modules/sum.cc"
      ]
    }
  ]
}

But at runtime I got this error:

node: symbol lookup error: /xxx/build/Release/addon.node: undefined symbol: _ZL12ReturnResultiRKN2v820FunctionCallbackInfoINS_5ValueEEE

That disappears if I don't use rand();

Answer 1

You forward declare your helper function like this:

static void ReturnResult(int result, const FunctionCallbackInfo<Value> &args);
//                       ^^^

but then implement it like this:

static void ReturnResult(double result, const FunctionCallbackInfo<Value> &args)
//                       ^^^^^^

So fix whichever one is wrong and your problem should go away.

---

You might like to know about demangler.com. That would have told you that the mangled symbol in your linker error corresponds to:

ReturnResult(int, v8::FunctionCallbackInfo<v8::Value> const&)

which I imagine would have been helpful.