How to Link Golang package to an existing C project (Using Go from C) on windows x86-64

Question

How to use Golang Generated libgolang.a from C code to build C executable: test.exe:

these commands makes executable binary 'test' in Ubuntu x86-64 and works fine (but not in Windows x86-64):

go build -buildmode c-archive -o libgolang.a
gcc -o test _main.c libgolang.a -lpthread

with:
this is main.go file:

package main

import "C"
import "fmt"

//export Add
func Add(a, b uint64) uint64 {
    return a + b
}

func main() {
    fmt.Println("Hi")
}

and this is _main.c file:

#include <stdio.h>
#include <stdint.h>
#include "libgolang.h"

int main()
{
    uint64_t a=10;
    uint64_t b=20;
    uint64_t c=Add(a,b);
    printf("%ld\n",c);
    return 0;
}

in Windows this command:

go build -buildmode c-archive -o libgolang.a

works fine and generates libgolang.a and libgolang.h files. libgolang.h:

/* Created by "go tool cgo" - DO NOT EDIT. */

/* package github.com/ARamazani/go/DLL */

/* Start of preamble from import "C" comments.  */




/* End of preamble from import "C" comments.  */


/* Start of boilerplate cgo prologue.  */

#ifndef GO_CGO_PROLOGUE_H
#define GO_CGO_PROLOGUE_H

typedef signed char GoInt8;
typedef unsigned char GoUint8;
typedef short GoInt16;
typedef unsigned short GoUint16;
typedef int GoInt32;
typedef unsigned int GoUint32;
typedef long long GoInt64;
typedef unsigned long long GoUint64;
typedef GoInt64 GoInt;
typedef GoUint64 GoUint;
typedef __SIZE_TYPE__ GoUintptr;
typedef float GoFloat32;
typedef double GoFloat64;
typedef float _Complex GoComplex64;
typedef double _Complex GoComplex128;

/*
  static assertion to make sure the file is being used on architecture
  at least with matching size of GoInt.
*/
typedef char _check_for_64_bit_pointer_matching_GoInt[sizeof(void*)==64/8 ? 1:-1];

typedef struct { const char *p; GoInt n; } GoString;
typedef void *GoMap;
typedef void *GoChan;
typedef struct { void *t; void *v; } GoInterface;
typedef struct { void *data; GoInt len; GoInt cap; } GoSlice;

#endif

/* End of boilerplate cgo prologue.  */

#ifdef __cplusplus
extern "C" {
#endif


extern GoUint64 Add(GoUint64 p0, GoUint64 p1);

#ifdef __cplusplus
}
#endif

but this command:

gcc -o test _main.c libgolang.a -lpthread

output:

libgolang.a(go.o):(.data+0x2150): undefined reference to `NtWaitForSingleObject'
libgolang.a(go.o):(.data+0x21b8): undefined reference to `WSAGetOverlappedResult'
libgolang.a(go.o):(.data+0x21d8): undefined reference to `timeBeginPeriod'
collect2.exe: error: ld returned 1 exit status

go version go1.7rc3 windows/amd64

I want to use this libgolang.a from C code to build C executable: test.exe

any workaround?

some useful links:

http://blog.ralch.com/tutorial/golang-sharing-libraries/
Using Go code in an existing C project
Using Go on existing C project

Answer 1

The Microsoft Windows always trick us!

But for production code my suggestion is use the optimization compile commands below:

go build -ldflags "-s -w" -buildmode c-archive -o libgolang.a

The parameter -ldflags "-s -w", will reduze the final file size.

The "libgolang.a" shrink from 4.295.562 to 1.994.554.

And the "test.exe" shrink from 3.430.485 to 1.715.561.

I guess this is a desired behavior!

Answer 2

Finally found at least one way:
using this file main.go:

package main

import "C"
import "fmt"

//export Add
func Add(a, b uint64) uint64 {
    return a + b
}

func main() {
    fmt.Println("Hi")
}

run this command:

go build -buildmode c-archive -o libgolang.a

to generate libgolang.a and libgolang.h then using _main.c:

#include <stdio.h>
#include <stdint.h>
#include "libgolang.h"

int main()
{
    uint64_t a=10;
    uint64_t b=20;
    uint64_t c=Add(a,b);
    printf("%ld\n",c);
    return 0;
}

this is the answer (this works for me):

gcc -o test _main.c libgolang.a -lWinMM -lntdll -lWS2_32

that test.exe created.

run:

test.exe

output:

30