VS Code Linux Devcontainer中C项目（GoogleTest+CMake）构建错误排查

项目背景 #

在VS Code的Linux开发容器（Devcontainer）中搭建集成GoogleTest与CMake的C项目，已将googletest仓库克隆到项目内的googletest文件夹中。

开发容器Dockerfile #

FROM mcr.microsoft.com/devcontainers/cpp:0-ubuntu-22.04

ARG REINSTALL_CMAKE_VERSION_FROM_SOURCE="3.22.2"

# Optionally install the cmake for vcpkg
COPY ./reinstall-cmake.sh /tmp/

RUN if [ "${REINSTALL_CMAKE_VERSION_FROM_SOURCE}" != "none" ]; then \
        chmod +x /tmp/reinstall-cmake.sh && /tmp/reinstall-cmake.sh ${REINSTALL_CMAKE_VERSION_FROM_SOURCE}; \
    fi \
    && rm -f /tmp/reinstall-cmake.sh

# Add googletest and cmake 
RUN apt-get update && sudo apt-get update && sudo apt-get install -y build-essential libgtest-dev

CMakeLists.txt #

cmake_minimum_required(VERSION 3.14)
project(Piscine-42)

# GoogleTest requires at least C++14
set(CMAKE_CXX_STANDARD 14)
# set for C 
set(CMAKE_C_STANDARD 99)

add_subdirectory(googletest) # add googletest subdirectory

include_directories(googletest/include) # this is so we can #include <gtest/gtest.h>

add_executable(test_return_one test_return_one.cpp) # add this executable

target_link_libraries(test_return_one PRIVATE gtest) # link google test to this executable

被测代码 #

return_one.c

#include "return_one.h"

int return_one(void)
{
    return (1);
}

return_one.h

#include "return_one.h"

int return_one(void)
{
    return (1);
}

测试代码 #

test_return_one.cpp

#include "gtest/gtest.h"
extern "C" {
#include "return_one.h"
}

TEST(t_return_one, returns_1)
{
    EXPECT_EQ(1,return_one());  
}

int main(int argc, char **argv)
{
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}

构建错误信息 #

使用VS Code的CMake-tools扩展构建时出现以下错误：

[main] Building folder: Piscine-42 test_return_one
[build] Starting build
[proc] Executing command: /usr/local/bin/cmake --build /workspaces/Piscine-42/build --config Debug --target test_return_one --
[build] [1/1 100% :: 0.266] Linking CXX executable test_return_one
[build] FAILED: test_return_one 
[build] : && /usr/bin/g++ -g  CMakeFiles/test_return_one.dir/test_return_one.cpp.o -o test_return_one  lib/libgtest.a && :
[build] /usr/bin/ld: CMakeFiles/test_return_one.dir/test_return_one.cpp.o: in function `t_return_one_returns_1_Test::TestBody()':
[build] /workspaces/Piscine-42/test_return_one.cpp:9: undefined reference to `return_one'
[build] collect2: error: ld returned 1 exit status
[build] ninja: build stopped: subcommand failed.
[proc] The command: /usr/local/bin/cmake --build /workspaces/Piscine-42/build --config Debug --target test_return_one -- exited with code: 1 and signal: null
[build] Build finished with exit code 1

解决方法 #

问题根源 #

1. 链接阶段未找到return_one函数的实现：当前CMake仅编译了测试代码test_return_one.cpp，未将被测的return_one.c加入构建目标，导致链接时缺失函数实现。
2. 头文件循环引用：return_one.h中包含自身，会引发重复定义问题。

具体修复步骤 #

1. 修复头文件循环引用
   修改return_one.h，添加头文件保护防止重复包含：

#ifndef RETURN_ONE_H
#define RETURN_ONE_H

int return_one(void);

#endif

2. 修改CMakeLists.txt，加入被测代码
   将被测C代码编译为静态库，再与测试可执行文件链接，修改后的配置如下：

cmake_minimum_required(VERSION 3.14)
project(Piscine-42)

# GoogleTest requires at least C++14
set(CMAKE_CXX_STANDARD 14)
set(CMAKE_C_STANDARD 99)

# 添加googletest子目录
add_subdirectory(googletest)

# 将被测代码编译为静态库
add_library(return_one_lib STATIC return_one.c)

# 包含头文件目录
include_directories(
    googletest/include
    ${PROJECT_SOURCE_DIR}
)

# 创建测试可执行文件
add_executable(test_return_one test_return_one.cpp)

# 链接测试库与被测库
target_link_libraries(test_return_one PRIVATE gtest return_one_lib)

3. 重新构建项目
   在VS Code中执行CMake: Configure重新生成构建配置，再执行CMake: Build即可完成构建。

内容的提问来源于stack exchange，提问作者ThrowsError