Question

我正在创建一个简单的C ++项目来与CMake相处，但我做不正确，因此我的应用无法成功构建（链接）（注意：我对当前的CMake =版本3.14感兴趣）。它是这样组织的命令行计算器：

calculator/
  CMakeLists.txt
  application/
    CMakeLists.txt
    src/
      ...
  libraries/
    mymath/
      CMakeLists.txt
      include/
        mymath/
          mymath.h
      src/
        ...

要构建它，请手动执行：

1 - create static library: libmymath.a (yep, I'm on Linux)
2 - create object file: application.o
3 - link them together into: application (executable)

我已经从cmake.org上阅读了一些官方文档以及一些教程，但是无法用它们解决（顺便说一句，这些教程/帮助中有许多是新的，但是对于旧版本的cmake，如果没有，我可以找不到它们涵盖这种情况，或者实际上从头到尾都没有（这不是很先进，并且需要先有关于做事的知识，例如首先使用自己的功能扩展cmake等）。

我还查找了现有的cmake文件，但只发现了最近写的旧文件：C（例如googletest社区驱动的cmake文件）... 我的问好事π！在哪里？

我当前的CMakeLists.txt编写如下：

# top level CMakeLists.txt
cmake_minimum_required (VERSION 3.14.3)
project (calculator
    VERSION 1.0.0
    DESCRIPTION "nah"
    LANGUAGES CXX)

add_subdirectory(application)
add_subdirectory (library/mymath)

target_link_libraries (calculator-app mymath)

# application/CMakeLists.txt
cmake_minimum_required (VERSION 3.14)
project (calculator-app
    VERSION 1.0.0
    DESCRIPTION "simple arythmetic command-line calculator"
    LANGUAGES CXX)

add_executable (calculator-app)

target_sources (calculator-app PRIVATE
    ${PROJECT_SOURCE_DIR}/src/main.cpp
    ${PROJECT_SOURCE_DIR}/src/cli.cpp
    ${PROJECT_SOURCE_DIR}/src/expression.cpp)

# library/mymath/CMakeLists.txt
cmake_minimum_required (VERSION 3.14)
project (mymath
    VERSION 1.0.0
    DESCRIPTION "professional prod-ready heavly-opt math impl"
    LANGUAGES CXX)

add_library (mymath STATIC)

target_sources(mymath PUBLIC
    ${PROJECT_SOURCE_DIR}/src/add.cpp
    ${PROJECT_SOURCE_DIR}/src/sub.cpp
    ${PROJECT_SOURCE_DIR}/src/mul.cpp
    ${PROJECT_SOURCE_DIR}/src/div.cpp)

target_include_directories(mymath INTERFACE
    ${PROJECT_SOURCE_DIR}/include)

目前，它可以正常工作：

# being in calculator/
$ mkdir build
$ cd build
$ cmake ..

然后失败：

$ make

有错误：

Scanning dependencies of target mymath
[  7%] Building CXX object library/mymath/CMakeFiles/mymath.dir/src/add.cpp.o
[ 15%] Building CXX object library/mymath/CMakeFiles/mymath.dir/src/sub.cpp.o
[ 23%] Building CXX object library/mymath/CMakeFiles/mymath.dir/src/mul.cpp.o
[ 30%] Building CXX object library/mymath/CMakeFiles/mymath.dir/src/div.cpp.o
[ 38%] Linking CXX static library libmymath.a
[ 38%] Built target mymath
Scanning dependencies of target calculator-app
[ 46%] Building CXX object application/CMakeFiles/calculator-app.dir/src/main.cpp.o
[ 53%] Building CXX object application/CMakeFiles/calculator-app.dir/src/cli.cpp.o
[ 61%] Building CXX object application/CMakeFiles/calculator-app.dir/src/expression.cpp.o
[ 69%] Building CXX object application/CMakeFiles/calculator-app.dir/__/library/mymath/src/add.cpp.o
[ 76%] Building CXX object application/CMakeFiles/calculator-app.dir/__/library/mymath/src/sub.cpp.o
[ 84%] Building CXX object application/CMakeFiles/calculator-app.dir/__/library/mymath/src/mul.cpp.o
[ 92%] Building CXX object application/CMakeFiles/calculator-app.dir/__/library/mymath/src/div.cpp.o
[100%] Linking CXX executable calculator-app
/usr/bin/ld: CMakeFiles/calculator-app.dir/src/expression.cpp.o: in function `OperatorsMapping::load()':
expression.cpp:(.text+0x151): undefined reference to `mymath::add(int, int)'
/usr/bin/ld: expression.cpp:(.text+0x18a): undefined reference to `mymath::sub(int, int)'
/usr/bin/ld: expression.cpp:(.text+0x1c3): undefined reference to `mymath::mul(int, int)'
/usr/bin/ld: expression.cpp:(.text+0x1fc): undefined reference to `mymath::div(int, int)'
/usr/bin/ld: expression.cpp:(.text+0x235): undefined reference to `mymath::div(int, int)'
collect2: error: ld returned 1 exit status
make[2]: *** [application/CMakeFiles/calculator-app.dir/build.make:175: application/calculator-app] Error 1
make[1]: *** [CMakeFiles/Makefile2:91: application/CMakeFiles/calculator-app.dir/all] Error 2
make: *** [Makefile:84: all] Error 2

我尝试将顶级CMakeLists.txt文件与application /中的其中一个合并，并将库目录移至application /中，但是没有用。

我使用了错误的命令吗？还是可能造成结构不良？或者也许我还在以错误的方式思考cmake？

我很高兴发现这一点，并且我一定会感谢一些很好的教程，这些教程彻底地完成了现代cmake的常见工作：）。

如何在CMake> 3.0版中将静态库目标与可执行目标链接起来

0 个答案: