使用Conan 2.0安装的Catch2库在CMake中链接失败求助

问题复现 #

项目文件结构：

• add.hpp
• add-test.cpp
• CMakeLists.txt
• conanfile.txt
• build/

各文件内容：

add.hpp #

inline int add(int a, int b) { return a + b; }

add-test.cpp #

#include <catch2/catch_all.hpp>
#include "add.hpp"

TEST_CASE("testing add") {
    REQUIRE(add(1, 1) == 2);
}

conanfile.txt #

[requires]
catch2/3.3.1

[generators]
CMakeDeps
CMakeToolchain

原CMakeLists.txt #

cmake_minimum_required(VERSION 3.5)

project(add LANGUAGES CXX VERSION 0.0.0)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

set(CMAKE_TOOLCHAIN_FILE "build/conan_toolchain.cmake")
# Required to be set.
set(CMAKE_BUILD_TYPE "Debug")
# CMake can't find Conan packages without these two lines
list(APPEND CMAKE_MODULE_PATH ${CMAKE_BINARY_DIR})
list(APPEND CMAKE_PREFIX_PATH ${CMAKE_BINARY_DIR})

find_package(Catch2 REQUIRED)

include_directories(${Catch2_INCLUDE_DIR})

add_executable(add-test add-test.cpp)

target_link_libraries(add-test Catch2::Catch2WithMain)

Conan配置文件 #

[settings]
arch=x86_64
build_type=Release
compiler=gcc
compiler.cppstd=gnu17
compiler.libcxx=libstdc++11
compiler.version=12.2
os=Linux

构建命令 #

conan install . --output-folder=build --build=missing
cd build
cmake ..
cmake --build .

错误信息 #

构建时出现大量Catch2相关链接错误，例如：

/usr/bin/ld: CMakeFiles/add-test.dir/add-test.cpp.o: in function `Catch::BinaryExpr<int, int>::~BinaryExpr()':
/home/fungor/.conan2/p/catchff10ed8b5da5a/p/include/catch2/internal/catch_decomposer.hpp:73: undefined reference to `Catch::ITransientExpression::~ITransientExpression()'
...

问题原因 #

1. 构建类型不匹配：Conan安装依赖时使用Release构建类型（配置文件中build_type=Release），但CMake手动设置CMAKE_BUILD_TYPE=Debug，导致编译生成的目标文件（Debug）与链接的Catch2库（Release）构建类型不一致，符号无法匹配。
2. CMake配置错误：
   • CMAKE_TOOLCHAIN_FILE设置位置错误，必须在project命令之前，否则toolchain配置无法生效。
   • 手动设置CMAKE_BUILD_TYPE会覆盖ConanToolchain传递的构建类型，导致不一致。
   • include_directories(${Catch2_INCLUDE_DIR})属于冗余配置，find_package(Catch2 REQUIRED)后，Catch2::Catch2WithMain目标已包含头文件路径。

修复方案 #

1. 统一构建类型 #

确保Conan安装和CMake编译使用相同的构建类型，二选一即可：

选项A：改用Debug构建类型

修改Conan配置文件的build_type为Debug：

[settings]
arch=x86_64
build_type=Debug
compiler=gcc
compiler.cppstd=gnu17
compiler.libcxx=libstdc++11
compiler.version=12.2
os=Linux

选项B：改用Release构建类型

移除CMakeLists.txt中set(CMAKE_BUILD_TYPE "Debug")这一行，由ConanToolchain传递构建类型。

2. 修正CMakeLists.txt #

cmake_minimum_required(VERSION 3.5)

# 必须在project之前设置toolchain文件
set(CMAKE_TOOLCHAIN_FILE "${CMAKE_CURRENT_SOURCE_DIR}/build/conan_toolchain.cmake")

project(add LANGUAGES CXX VERSION 0.0.0)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# 移除手动设置的CMAKE_BUILD_TYPE，由ConanToolchain传递
# set(CMAKE_BUILD_TYPE "Debug")

list(APPEND CMAKE_MODULE_PATH ${CMAKE_BINARY_DIR})
list(APPEND CMAKE_PREFIX_PATH ${CMAKE_BINARY_DIR})

find_package(Catch2 REQUIRED)

# 移除冗余的include_directories
# include_directories(${Catch2_INCLUDE_DIR})

add_executable(add-test add-test.cpp)

target_link_libraries(add-test Catch2::Catch2WithMain)

3. 重新构建 #

清理旧构建文件后执行命令：

rm -rf build
conan install . --output-folder=build --build=missing
cd build
cmake ..
cmake --build .

验证 #

构建成功后运行测试：

./add-test

内容的提问来源于stack exchange，提问作者Fungor