cmake未定义函数的引用 [英] cmake undefined reference to function

问题描述

下面的项目结构是一个简化的例子。我尝试将其归档到最小的文件大小以重现我的问题。

 。 
├──CMakeLists.txt 
├──subdir1 
│├──CMakeLists.txt 
│└──subsubdir1 
│├──CMakeLists.txt 
│├──Example.cpp 
│└──示例.h 
└──subdir2 
├──CMakeLists.txt 
├──main.cpp 
└──subsubdir1 
├──CMakeLists.txt 
├──ExampleCreator.cpp 
└──ExampleCreator.h 
  

./ CMakeLists.txt

  cmake_minimum_required（VERSION 2.8） 
 project（test）
 
宏（add_sources）
文件（RELATIVE_PATH _relPath$ {CMAKE_SOURCE_DIR}$ {CMAKE_CURRENT_SOURCE_DIR}）
 foreach（_src $ { ARGN}）
 if（_relPath）
 list（APPEND SRCS$ {_ relPath} / $ {_ src}）
 else（）
 list } 
 endif（）
 endforeach（）
 if（_relPath）
＃将SRCS传播到父目录
 set（SRCS $ {SRCS} PARENT_SCOPE）
 endif（）
 endmacro（）
 
 add_subdirectory（subdir1）
 add_subdirectory（subdir2）
 
 add_executable（test $ {SRCS}）
  

subdir1 / CMakeLists.txt

  add_subdirectory（subsubdir1）
  

subdir1 / subsubdir1 / CMakeLists.txt

  add_sources（Example.cpp）
  

subdir1 / subsubdir1 / Example.h

  #ifndef EXAMPLE_H 
 #define EXAMPLE_H 
 
 class Example 
 {
 public：
 Example（）; 
 virtual〜Example（）; 
}; 
 
 #endif 
  

subdir1 / subsubdir1 / Example.cpp

  #include< stdio.h> 
 #includeExample.h
 
 Example :: Example（）
 {
 printf（Inside Example constructor\\\
）; 
} 
 
示例::〜Example（）
 {
} 
  

subdir2 / CMakeLists.txt

  add_subdirectory（subsubdir1）
 add_sources cpp）
  

subdir2 / main.cpp

  #includesubsubdir1 / ExampleCreator.h
 
 int main（int argc，char ** argv）
 {
 ExampleCreator creator; 
 return 0; 
} 
  

subdir2 / subsubdir1 / CMakeLists.txt

  add_sources（ExampleCreator.cpp）
  

subdir2 / subsubdir1 / ExampleCreator.h

  #ifndef EXAMPLE_CREATOR_H 
 #define EXAMPLE_CREATOR_H 
 
 ExampleCreator 
 {
 public：
 ExampleCreator（）; 
 virtual〜ExampleCreator（）; 
}; 
 
 #endif 
  

subdir2 / subsubdir1 / ExampleCreator.cpp

  #includeExampleCreator.h
 #include../../subdir1/subsubdir1/Example.h
 
 ExampleCreator :: ExampleCreator（）
 {
示例* ex1 = new Example（）; 
} 
 
 ExampleCreator ::〜ExampleCreator（）
 {
} 
  

我希望这是一个非常简单的理解，如何CMake处理依赖关系。此编译没有错误，但在链接期间失败。下面的 make 输出显示 Example.cpp 甚至不编译，我不明白为什么。 p>

  user>：〜/ src / test / build $ make 
扫描目标测试的依赖关系
 [50％ ]构建CXX对象CMakeFiles / test.dir / subdir2 / subsubdir1 / ExampleCreator.cpp.o 
 [100％]构建CXX对象CMakeFiles / test.dir / subdir2 / main.cpp.o 
链接CXX可执行文件test 
 CMakeFiles / test.dir / subdir2 / subsubdir1 / ExampleCreator.cpp.o：在函数`ExampleCreator :: ExampleCreator（）'中：
 ExampleCreator.cpp :(。text + 0x2b）：undefined `example :: Example（）'
 collect2：ld返回1退出状态
 make [2]：*** [test]错误1 
 make [1]：*** [CMakeFiles /test.dir/all]错误2 
 make：*** [all]错误2 
  

所有的源都附加到根据 CMakeLists.txt 文件中的 SRCS 变量。那么，为什么 Example.cpp 得不到编译？或链接？ c code> subdir1 不会生成二进制文件。添加以下内容：

 项目（示例）
 add_library（Example Example.cpp）
  

而不是您的 add_sources 。之后，您需要告诉使用它来链接它的项目：

  TARGET_LINK_LIBRARIES（subdir2示例）
  

如果您的名称不同，请记录这些命令的功能。

The project structure below is a simplified example. I tried to boil it down to the minimal amount of files to reproduce my issue.

.
├── CMakeLists.txt
├── subdir1
│   ├── CMakeLists.txt
│   └── subsubdir1
│       ├── CMakeLists.txt
│       ├── Example.cpp
│       └── Example.h
└── subdir2
    ├── CMakeLists.txt
    ├── main.cpp
    └── subsubdir1
        ├── CMakeLists.txt
        ├── ExampleCreator.cpp
        └── ExampleCreator.h

./CMakeLists.txt

cmake_minimum_required(VERSION 2.8)
project(test)

macro(add_sources)
    file (RELATIVE_PATH _relPath "${CMAKE_SOURCE_DIR}" "${CMAKE_CURRENT_SOURCE_DIR}")
    foreach (_src ${ARGN})
        if (_relPath)
            list (APPEND SRCS "${_relPath}/${_src}")
        else()
            list (APPEND SRCS "${_src}")
        endif()
    endforeach()
    if (_relPath)
        # propagate SRCS to parent directory
        set (SRCS ${SRCS} PARENT_SCOPE)
    endif()
endmacro()

add_subdirectory(subdir1)
add_subdirectory(subdir2)

add_executable(test ${SRCS})

subdir1/CMakeLists.txt

add_subdirectory(subsubdir1)

subdir1/subsubdir1/CMakeLists.txt

add_sources(Example.cpp)

subdir1/subsubdir1/Example.h

#ifndef EXAMPLE_H
#define EXAMPLE_H

class Example
{
public:
    Example();
    virtual ~Example();
};

#endif

subdir1/subsubdir1/Example.cpp

#include <stdio.h>
#include "Example.h"

Example::Example()
{
    printf("Inside Example constructor\n");
}

Example::~Example()
{
}

subdir2/CMakeLists.txt

add_subdirectory(subsubdir1)
add_sources(main.cpp)

subdir2/main.cpp

#include "subsubdir1/ExampleCreator.h"

int main(int argc, char** argv)
{
    ExampleCreator creator;
    return 0;
}

subdir2/subsubdir1/CMakeLists.txt

add_sources(ExampleCreator.cpp)

subdir2/subsubdir1/ExampleCreator.h

#ifndef EXAMPLE_CREATOR_H
#define EXAMPLE_CREATOR_H

class ExampleCreator
{
public:
    ExampleCreator();
    virtual ~ExampleCreator();
};

#endif

subdir2/subsubdir1/ExampleCreator.cpp

#include "ExampleCreator.h"
#include "../../subdir1/subsubdir1/Example.h"

ExampleCreator::ExampleCreator()
{
    Example* ex1 = new Example();
}

ExampleCreator::~ExampleCreator()
{
}

I'm hoping this is a really simple lack of understanding of how CMake handles dependencies. This compiles without error, but fails during linking. The make output below shows that Example.cpp isn't even compiling and I don't understand why.

user>:~/src/test/build$ make
Scanning dependencies of target test
[ 50%] Building CXX object CMakeFiles/test.dir/subdir2/subsubdir1/ExampleCreator.cpp.o
[100%] Building CXX object CMakeFiles/test.dir/subdir2/main.cpp.o
Linking CXX executable test
CMakeFiles/test.dir/subdir2/subsubdir1/ExampleCreator.cpp.o: In function `ExampleCreator::ExampleCreator()':
ExampleCreator.cpp:(.text+0x2b): undefined reference to `Example::Example()'
collect2: ld returned 1 exit status
make[2]: *** [test] Error 1
make[1]: *** [CMakeFiles/test.dir/all] Error 2
make: *** [all] Error 2

All the sources are appended to the SRCS variable in the root CMakeLists.txt file from what I can tell. So, why isn't Example.cpp getting compiled? or linked?

解决方案

The directory subdir1 doesn't generate a binary. Add this:

project(Example)
add_library(Example Example.cpp)

instead of your add_sources. After this, you need to tell the project that uses it to link against it:

TARGET_LINK_LIBRARIES(subdir2 Example)

If your names differ, document yourself on the functionalities of these commands.

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