我发现了另一个案子，所以我认为你们都错了。

这是我所拥有的:

/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../x86_64-suse-linux/bin/ld: eggtrayicon.o: undefined reference to symbol 'XFlush'
/usr/lib64/libX11.so.6: error adding symbols: DSO missing from command line

问题是，命令行中没有包含- lx11 -尽管libX11. exe文件。所以应该作为依赖项添加，因为在参数中还有GTK和GNOME库。

所以，对我来说，唯一的解释是，这条信息可能是为了帮助你，但它没有正确地做到这一点。这可能很简单:提供该符号的库没有添加到命令行。

请注意POSIX中有关链接的三个重要规则:

Dynamic libraries have defined dependencies, so only libraries from the top-dependency should be supplied in whatever order (although after the static libraries) Static libraries have just undefined symbols - it's up to you to know their dependencies and supply all of them in the command line The order in static libraries is always: requester first, provider follows. Otherwise you'll get undefined symbol message, just like when you forgot to add the library to the command line When you specify the library with -l<name>, you never know whether it will take lib<name>.so or lib<name>.a. The dynamic library is preferred, if found, and static libraries only can be enforced by compiler option - that's all. And whether you have any problems as above, it depends on whether you had static or dynamic libraries Well, sometimes the dependencies may be lacking in dynamic libraries :D

如果你正在使用CMake，有一些方法可以解决这个问题:

解决方案1:最优雅的一个

add_executable(...)
target_include_directories(...)
target_link_libraries(target_name pthread)

方案2:使用CMake find_package

find_package(Threads REQUIRED) # this will generate the flag for CMAKE_THREAD_LIBS_INIT

add_executable(...)
target_include_directories(...)
target_link_libraries(target_name ${CMAKE_THREAD_LIBS_INIT})

解决方案3:修改CMake标志

# e.g. with C++ 17, change to other version if you need
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17 -pthread")

我发现有时候链接程序抱怨的库并不是引起问题的那个库。也许有一个聪明的方法来解决问题，但这就是我所做的:

在link命令中注释掉所有链接的库。 清除所有的.o， .so等(通常Clean就足够了，但你可能想要运行一个递归的find + rm，或类似的东西)。 每次取消link命令中的一个库的注释，并根据需要重新排列顺序。

@peter karasev:我在CentOS7上的gcc 4.8.2 cmake项目中遇到了同样的问题。“target_link_libraries”部分中的库的顺序很重要。我猜cmake只是将列表原样传递给链接器，也就是说，它不会尝试并计算出正确的顺序。这是合理的——当你思考它时，cmake不知道正确的顺序是什么，直到链接成功完成。

我发现我也犯了同样的错误。我正在用lapack和blas编译代码。当我切换两个库的调用顺序时，错误就消失了。

"LAPACK_LIB = - lapack -lblas"工作的地方 "LAPACK_LIB = -lblas - lapack"给出了上面描述的错误。

我发现了另一个案子，所以我认为你们都错了。

这是我所拥有的:

/usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../x86_64-suse-linux/bin/ld: eggtrayicon.o: undefined reference to symbol 'XFlush'
/usr/lib64/libX11.so.6: error adding symbols: DSO missing from command line

问题是，命令行中没有包含- lx11 -尽管libX11. exe文件。所以应该作为依赖项添加，因为在参数中还有GTK和GNOME库。

所以，对我来说，唯一的解释是，这条信息可能是为了帮助你，但它没有正确地做到这一点。这可能很简单:提供该符号的库没有添加到命令行。

请注意POSIX中有关链接的三个重要规则:

Dynamic libraries have defined dependencies, so only libraries from the top-dependency should be supplied in whatever order (although after the static libraries) Static libraries have just undefined symbols - it's up to you to know their dependencies and supply all of them in the command line The order in static libraries is always: requester first, provider follows. Otherwise you'll get undefined symbol message, just like when you forgot to add the library to the command line When you specify the library with -l<name>, you never know whether it will take lib<name>.so or lib<name>.a. The dynamic library is preferred, if found, and static libraries only can be enforced by compiler option - that's all. And whether you have any problems as above, it depends on whether you had static or dynamic libraries Well, sometimes the dependencies may be lacking in dynamic libraries :D

错误信息取决于发行版/编译器版本:

Ubuntu漂亮的:

/usr/bin/ld: /mnt/root/ffmpeg-2.1.1//libavformat/libavformat.a(http.o): undefined reference to symbol 'inflateInit2_'
/lib/x86_64-linux-gnu/libz.so.1: error adding symbols: DSO missing from command line

Ubuntu Raring:(更多信息)

/usr/bin/ld: note: 'uncompress' is defined in DSO /lib/x86_64-linux-gnu/libz.so.1 so try adding it to the linker command line

解决方案:在链接阶段，您可能会在编译步骤中丢失一个库。在我的例子中，我在makefile / GCC标志中添加了'-lz'。

背景:DSO是一个动态共享对象或共享库。