将两个库与CMake连接起来

Question

档案结构：

CMakeLists.txt
src/
    evolution.cpp
    evolution.h
    main.cpp
    helpers/
        disposable.h
    engine/
        game.h
        game.cpp

CMakeLists.txt：

cmake_minimum_required(VERSION 3.17)
project(evolution)

add_library(helpers
    src/helpers/disposable.h)
set_target_properties(helpers PROPERTIES LINKER_LANGUAGE CXX)

add_library(engine
    src/engine/game.h
    src/engine/game.cpp)

add_executable(evolution src/main.cpp)

target_link_libraries(evolution engine helpers)

Game类(game.h)继承自Diposable (disposable.h)，但我无法在game.h文件中使用简单的#include "disposable.h"构建项目。

如何配置CMake，使engine库能够看到helpers库？

CMake错误：

[ 20%] Building CXX object CMakeFiles/engine.dir/src/engine/game.cpp.o
In file included from /home/shane/projects/evolution/src/engine/game.cpp:1:
/home/shane/projects/evolution/src/engine/game.h:4:10: fatal error: disposable.h: No such file or directory
    4 | #include "disposable.h"
      |          ^~~~~~~~~~~~~~
compilation terminated.

Answer 1

向项目添加标头只会帮助IDE找到标头。它不会改变构建指令。相反，您需要将target_include_directories()与INTERFACE或PUBLIC部分一起使用，以获取链接到该部分的任何库，从而将包含目录添加到自身。

目前，您的帮助程序库更像是一个接口。要使这个最小的示例正常工作，请执行以下操作：

cmake_minimum_required(VERSION 3.17)
project(evolution)

add_library(helpers INTERFACE) # INTERFACE is good for header-only libraries
target_include_directories(helpers INTERFACE src/helpers) 

add_library(engine
    src/engine/game.h
    src/engine/game.cpp)

add_executable(evolution src/main.cpp)

target_link_libraries(evolution engine helpers)

现在包含角括号：#include <disposable.h>

如果您的库变得更复杂(不仅仅是头文件)，那么用源替换INTERFACE中的add_library。要使helpers库和链接到它的任何库都可以使用目录，请将INTERFACE更改为target_include_directories中的PUBLIC。

cmake_minimum_required(VERSION 3.17)
project(evolution)

add_library(helpers src/helpers/helper.cpp)
target_include_directories(helpers PUBLIC src/helpers)

add_library(engine
    src/engine/game.h
    src/engine/game.cpp)

add_executable(evolution src/main.cpp)

target_link_libraries(evolution engine helpers)