C ++ CMake将可执行文件链接到第三方依赖共享库时未定义的引用 [英] C++ CMake undefined reference when linking an executable to a third party dependant shared library

问题描述

我阅读了很多相关主题（例如 1 ， 2 ， 3 ），但是没有找到我自己的答案，所以这里。

我有一个CMake项目生成和可执行，让说x。我创建了一个名为a.so的共享库，它依赖于其他名为b.so的共享库。我想在x中使用a。

这里是我简化的xCMakelists.txt：

  SET（ROOT_DIR $ {CMAKE_CURRENT_SOURCE_DIR}）
 
 LINK_DIRECTORIES（$ {ROOT_DIR} / lib / a / bin /）＃包含liba.so 
 
 INCLUDE_DIRECTORIES（$ {ROOT_DIR} / lib / a / include /）＃包含a标头
 
 ADD_EXECUTABLE（x $ {SOURCE}）
 
 TARGET_LINK_LIBRARIES （xa）
  

x编译输出extract：

$ b b

 链接CXX可执行文件../bin/x 
 / usr / bin / cmake -E cmake_link_script CMakeFiles / x.dir / link.txt --verbose = 1 
 / usr / lib64 / ccache / c ++ -std = c ++ 0x CMakeFiles / x.dir / src / main /Main.cpp.o 
 ... -L /.../ lib / a / bin -rdynamic -la -Wl，-rpath，/ ... / lib / a / bin 
  

a和b做编译。

问题是当我想编译x我在链接时得到错误：未定义的引用'function name'。
我试图链接到b，但它仍然不工作。

这里b相同的错误...

 链接CXX可执行文件../bin/x 
 / usr / bin / cmake  - E cmake_link_script CMakeFiles / x.dir / link.txt --verbose = 1 
 / usr / lib64 / ccache / c ++ -std = c ++ 0x CMakeFiles / x.dir / src / main 
 / Main .cpp.o -o ../bin/x -L /.../lib/b/bin -L/.../lib/a/bin 
 -rdynamic -lb -la -Wl， - rpath，/ ... / lib / b / bin：/.../ lib / a / bin 
  

这里是错误输出：

  $ make 
 [20％]目标的自动moc x 
链接CXX可执行文件../bin/x 
 /.../lib/b/bin/b.so：未定义对`snd_pcm_sw_params_set_start_threshold'的引用
 /.../lib/b/bin/ b.so：未定义对`snd_seq_delete_simple_port'的引用
 /.../lib/b/bin/b.so：未定义对`snd_pcm_info_set_device'的引用
 /.../lib/b/bin/ b.so：未定义引用`snd_pcm_sw_params'
 /.../lib/b/bin/b.so：未定义对`snd_pcm_sw_params_set_silence_threshold'的引用
 /.../lib/b/bin/ b.so：未定义引用`snd_pcm_hw_params_any'
 /.../lib/b/bin/b.so：未定义对`snd_seq_drain_output'的引用
 /.../lib/b/bin/ b.so：未定义引用`snd_ctl_pcm_next_device'
 
 ... 
 
 collect2：错误：ld返回1退出状态
 CMakeFiles / x.dir / build。 make：163：目标'../bin/x'失败的食谱
 make [2]：*** [../bin/x]错误1 
 CMakeFiles / Makefile2：60：recipe for目标'CMakeFiles / x.dir / all'失败
 make [1]：*** [CMakeFiles / x.dir / all]错误2 
 Makefile：76：目标'all'失败的食谱
 make：*** [all]错误2 
  

我看不到什么问题，我现在很困惑，因为我尝试了很多事情来让事情工作...但没有工作。

有什么想法吗？

谢谢！

解决方案

我问过上面的注释中的错误输出，因为它可以帮助搜索未定义的符号/参考。

因此，看来你的b.so找不到ALSA库。如果您使用 CMake 3.0 （和更高版本），您可以通过

添加到 CMakeLists.txt b $ b

，并可将 $ {ALSA_INCLUDE_DIR} 附加到include路径和 $ {ALSA_LIBRARY} 到您的链接器路径。

I read a lot of related topics (like 1, 2, 3) but did not find the answer by myself so here I am.

I have a CMake project that builds and executable, let say "x". I created a shared library named "a.so" that depends on other shared library called "b.so". I want to use "a" in "x".

Here is my simplified "x" CMakelists.txt:

SET(ROOT_DIR ${CMAKE_CURRENT_SOURCE_DIR})

LINK_DIRECTORIES(${ROOT_DIR}/lib/a/bin/) # contains liba.so

INCLUDE_DIRECTORIES(${ROOT_DIR}/lib/a/include/) # contains "a" headers

ADD_EXECUTABLE(x ${SOURCE})

TARGET_LINK_LIBRARIES(x a)

"x" compilation output extract:

Linking CXX executable ../bin/x
/usr/bin/cmake -E cmake_link_script CMakeFiles/x.dir/link.txt --verbose=1
/usr/lib64/ccache/c++   -std=c++0x    CMakeFiles/x.dir/src/main /Main.cpp.o 
 ... -L/.../lib/a/bin -rdynamic  -la  -Wl,-rpath,/.../lib/a/bin 

"a" and "b" do compile.

The problem is when I want to compile x I get errors when linking: undefined reference to 'function name'. I tried to link against "b" too but it's still not working.

Here "b" also appears but I get the same error...

Linking CXX executable ../bin/x
/usr/bin/cmake -E cmake_link_script CMakeFiles/x.dir/link.txt --verbose=1 
/usr/lib64/ccache/c++   -std=c++0x    CMakeFiles/x.dir/src/main 
/Main.cpp.o -o ../bin/x  -L/.../lib/b/bin -L/.../lib/a/bin 
-rdynamic -lb -la -Wl,-rpath,/.../lib/b/bin:/.../lib/a/bin 

Here is the error output:

 $ make
 [ 20%] Automatic moc for target x
 Linking CXX executable ../bin/x
 /.../lib/b/bin/b.so: undefined reference to `snd_pcm_sw_params_set_start_threshold'
 /.../lib/b/bin/b.so: undefined reference to `snd_seq_delete_simple_port'
 /.../lib/b/bin/b.so: undefined reference to `snd_pcm_info_set_device'
 /.../lib/b/bin/b.so: undefined reference to `snd_pcm_sw_params'
 /.../lib/b/bin/b.so: undefined reference to `snd_pcm_sw_params_set_silence_threshold'
 /.../lib/b/bin/b.so: undefined reference to `snd_pcm_hw_params_any'
 /.../lib/b/bin/b.so: undefined reference to `snd_seq_drain_output'
 /.../lib/b/bin/b.so: undefined reference to `snd_ctl_pcm_next_device'

 ...

 collect2: error: ld returned 1 exit status
 CMakeFiles/x.dir/build.make:163: recipe for target '../bin/x' failed
 make[2]: *** [../bin/x] Error 1
 CMakeFiles/Makefile2:60: recipe for target 'CMakeFiles/x.dir/all' failed
 make[1]: *** [CMakeFiles/x.dir/all] Error 2
 Makefile:76: recipe for target 'all' failed
 make: *** [all] Error 2

I don't see what's wrong and I'm now confused as I tried many things to get the thing working... but nothing worked.

Any idea?

Thanks!

解决方案

I asked you for the error output in the comments above, because it can help to search the undefined symbols/references.

So, it seems that your b.so cannot find the ALSA library. If you use CMake 3.0 (and up) you can add it to your CMakeLists.txt via

find_package( ALSA )

and can append ${ALSA_INCLUDE_DIR} to your include path and ${ALSA_LIBRARY} to your linker path.

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