使用GCC(MinGW32)编译依赖静态库的DLL遇链接错误求助

我有一个CGO生成的静态库libsecondary.a，想基于它生成动态库，要求在DLL_PROCESS_ATTACH事件中调用libsecondary.h里导出的OnProcessInit()函数。

我用了这条编译命令：

x86_64-w64-mingw32 -shared -L. -lsecondary -static-libgcc -static-libstdc++ -static .\dllmain.c

但编译失败，错误提示：

dllmain.c:(.text+0x9b): undefined reference to `OnProcessInit'

相关文件内容 #

头文件libsecondary.h

/* Code generated by cmd/cgo; DO NOT EDIT. */

/* package command-line-arguments */


#line 1 "cgo-builtin-export-prolog"

#include <stddef.h>

#ifndef GO_CGO_EXPORT_PROLOGUE_H
#define GO_CGO_EXPORT_PROLOGUE_H

#ifndef GO_CGO_GOSTRING_TYPEDEF
typedef struct { const char *p; ptrdiff_t n; } _GoString_;
#endif

#endif

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




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


/* Start of boilerplate cgo prologue.  */
#line 1 "cgo-gcc-export-header-prolog"

#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_t GoUintptr;
typedef float GoFloat32;
typedef double GoFloat64;
#ifdef _MSC_VER
#include <complex.h>
typedef _Fcomplex GoComplex64;
typedef _Dcomplex GoComplex128;
#else
typedef float _Complex GoComplex64;
typedef double _Complex GoComplex128;
#endif

/*
  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];

#ifndef GO_CGO_GOSTRING_TYPEDEF
typedef _GoString_ GoString;
#endif
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 __declspec(dllexport) void OnProcessInit();
#ifdef __cplusplus
}
#endif

dllmain.c文件

#include <windows.h>
#include <stdio.h>
#include "libsecondary.h"

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved)
{
    switch (fdwReason)
    {
    case DLL_PROCESS_ATTACH:
        printf("It works i guess");
        OnProcessInit();
        break;
    case DLL_THREAD_ATTACH:
        break;
    case DLL_THREAD_DETACH:
        break;
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

生成静态库的Go代码（用go build -buildmode=c-archive编译）

package main
import "C"
import (
    "unsafe"
    "syscall"
)

//export OnProcessInit
func OnProcessInit() {
    const (
        NULL  = 0
        MB_OK = 0
    )
    caption := "Hola"
    title := "desdegoo"
    ret, _, _ := syscall.NewLazyDLL("user32.dll").NewProc("MessageBoxW").Call(
        uintptr(NULL),
        uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(caption))),
        uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(title))),
        uintptr(MB_OK))
    if ret != 1 {
        return
    }
    return 
}
func main() {}

核心原因：链接库的顺序错误 #

MinGW链接器是按从左到右的顺序处理依赖的，你把静态库-lsecondary放在了源文件dllmain.c前面，导致链接器处理库的时候还不知道需要OnProcessInit这个符号，后续处理源文件时自然找不到该符号的定义。

修复步骤 #

1. 调整编译命令的参数顺序：把源文件dllmain.c放在链接库参数-lsecondary之前，让链接器先处理源文件，明确需要哪些符号，再从静态库中查找对应的定义。同时注意命令里要加上-gcc后缀，否则可能调用的不是编译器工具：

   x86_64-w64-mingw32-gcc -shared -L. -static-libgcc -static-libstdc++ -static .\dllmain.c -lsecondary
   

2. 额外注意事项：

   • 确保libsecondary.a和libsecondary.h都在当前目录下，或者用-L指定正确的库路径。
   • Go生成的C静态库依赖Go运行时，-static参数会把相关依赖静态链接进去，避免运行时找不到Go的动态库。

内容的提问来源于stack exchange，提问作者Cuervo