如何使用 CMake 将 Go 代码编译并链接到 C++

本篇文章给大家分享《如何使用 CMake 将 Go 代码编译并链接到 C++》，覆盖了Golang的常见基础知识，其实一个语言的全部知识点一篇文章是不可能说完的，但希望通过这些问题，让读者对自己的掌握程度有一定的认识(B 数)，从而弥补自己的不足，更好的掌握它。

我正在尝试将 go 代码编译到库中，然后使用 cmake 链接 c++ 和 lib。

我已经尝试过使用 gcc 制作共享库，如下 https://medium.com/swlh/build-and-use-go-packages-as-c-libraries-889eb0c19838。

go build -o cas.so -buildmode=c-shared cmd/c-mock-server/main.go
gcc -o main main.c ./cas.so

所以现在我需要创建共享库并使用 cmake 将其与 c++ 代码链接，但我真的不知道如何做到这一点

正确答案

在使用 cmake 之前构建项目结构：

# tree .
.
├── cmakelists.txt
├── go
│   ├── cmakelists.txt
│   ├── go.mod
│   └── module.go
└── test.cpp

文件

./cmakelists.txt

cmake_minimum_required(version 3.0)
project(test)

add_subdirectory(go)

set(target test)
set(srcs test.cpp)

add_executable(${target} ${srcs})
target_link_libraries(${target} goshim pthread)

./test.cpp

#include <iostream>
#include <string>
#include "go/module.h"

int main() {
    int res = add(1, 2);
    std::cout << res << std::endl;

    gostring str;
    str.p = "hello world";
    str.n = strlen(str.p);
    print(str);

    std::string s = "go-module";
    char *cstr = new char[s.length()+1];
    std::strcpy (cstr, s.c_str());

    cstr = strfxn(cstr);
    std::cout << cstr << std::endl;
    delete[] cstr;

    return 0;
}

./go/cmakelists.txt

cmake_minimum_required(version 3.0)
project(test_go)

set(target shim_go)

set(srcs module.go)
set(lib module.so)

add_custom_command(output ${cmake_current_binary_dir}/${lib}
  depends ${srcs}
  working_directory ${cmake_current_source_dir}
  command env gopath=${gopath} go build -buildmode=c-archive
  -o "${cmake_current_binary_dir}/${lib}"
  ${cmake_go_flags} ./...
  comment "building go library")

add_custom_target(${target} depends ${lib} ${header})
add_library(goshim static imported global)
add_dependencies(goshim ${target})
set_target_properties(goshim
  properties
  imported_location ${cmake_current_binary_dir}/${lib}
  interface_include_directories ${cmake_current_binary_dir})

./go/module.go

package main

import "c"

import (
    "sort"
    "fmt"
)

//export add
func add(a, b int) int {
    return a + b
}

//export sub
func sub(a, b int) int {
    return a - b
}

//export print
func print(str string) {
    fmt.printf("go prints: %s\n", str)
}

func strfxn(input string) string {
    return "hello " + input + " world"
}

//export strfxn
func strfxn(cinput *c.char) *c.char {
    // c data needs to be manually managed in memory.
    // but we will do it from c++.
    input := c.gostring(cinput)
    return c.cstring(strfxn(input))
}

//export sort
func sort(vals []int) {
    sort.ints(vals)
}

func main() {
    // we need the main function to make possible
    // cgo compiler to compile the package as c shared library
}

./go/go.mod

total 16
module demo/module

go 1.16

运行

# cmake .
-- The C compiler identification is AppleClang 12.0.0.12000032
-- The CXX compiler identification is AppleClang 12.0.0.12000032
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/demo

#  make
[ 33%] Building Go library
[ 33%] Built target shim_go
[ 66%] Building CXX object CMakeFiles/test.dir/test.cpp.o
[100%] Linking CXX executable test
[100%] Built target test

# ./test
3
Go prints: Hello World
Hello Go-Module World

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