CMake链接错误（未定义引用） [英] CMake linking error (undefined reference to)

问题描述

我正在使用SSL-Vision软件。它有一个示例客户，我一直试图将其与整个项目分开。我找到了自己编辑客户端所需的资源，因此我只是从软件中复制了它们，并使用CMake来构建我的客户端。

下面的项目结构被简化，缩小了

 。 
├──CMakeLists.txt 
├──main.cc 
├──建立
│├──CMakeLists.txt 
│└──messages_ssl_ .. 。（.cc / .h，每个4个）
└──src 
├──CMakeLists.txt 
└──（其他子目录和源/标题）
  

./ CMakeLists.txt ：

  cmake_minimum_required（版本2.6）
项目（TestClient）
 
 find_package（需要PkgConfig）
 pkg_check_modules（QTCORE_PKG QtCore）
 include_directories （$ {QTCORE_PKG_INCLUDE_DIRS}）
 
 include（FindProtobuf）
 find_package（需要Protobuf）
 include_directories（$ {PROTOBUF_INCLUDE_DIRS}）
 
 find_package（PkgConfig REQUI ）
 pkg_check_modules（GLIB_PKG glib-2.0）
 include_directories（$ {GLIB_PKG_INCLUDE_DIRS}）
 
 include_directories（ src）
 add_subdirectory（src）
 
 include_directories（ build）
 add_subdirectory（build）
 
 
 add_executable（clientTest clientTest.cc） 
 
 target_link_libraries（clientTest robocup_ssl_client messages_robocup_ssl_detection.pb messages_robocup_ssl_geometry.pb messages_robocup_ssl_wrapper.pb messages_robocup_ssl_refbox_log.pb netraw robocup_ssl_c $ p $ c $ p $ c $ p $ c $ p $ c $ p code b 
 
  ./ build / CMakeLists.txt ：
  add_library（messages_robocup_ssl_detection .pb共享messages_robocup_ssl_detection.pb.cc）
 
 add_library（messages_robocup_ssl_refbox_log.pb SHARED messages_robocup_ssl_refbox_log.pb.cc）
 
 add_library（messages_robocup_ssl） b 
 $ b add_library（messages_robocup_ssl_wrapper.pb SHARED messages_robocup_ssl_wrapper.pb.cc）
  
可以是 messages_ssl _... 文件中缺少的 #include ，但它们都是自动生成的，似乎是
 
 
 
在 messages_robocup_ssl_detection.pb.h 和 messages_robocup_ssl_detection.pb.h 仅包含protobuf。
 
 
 
在 messages_robocup_ssl_refbox_log.pb.h ：
  #include messages_robocup_ssl_detection.pb.h 
 //其他protobuf包含
  
在 messages_robocup_ssl_wrapper.h ：
  #include messages_robocup_ssl_detection.pb.h 
 #include messages_robocup_ssl_geometry.pb.h 
 //其他protobuf包括
  
在每个.cc文件中仅包含其标头和其他probubuf库。
 
 
 
最后，当我制作时，会产生以下错误：
 链接CXX可执行文件clientTest 
 build / libmessages_robocup_ssl_wrapper.pb.so：未定义对 SSL_GeometryData :: ByteSize（）const的引用 
 build / libmessages_robocup_ssl_wrapper.pb.so：未定义对SSL_GeometryData :: MergeFrom（SSL_GeometryData const& '
构建/库ages_robocup_ssl_wrapper.pb.so：对`protobuf_AddDesc_messages_5frobocup_5fssl_5fgeometry_2eproto（）的未定义引用
 build / libmessages_robocup_ssl_wrapper.pb.so：对SSL_GeometryData.bbsso的未定义引用对`SSL_GeometryData :: SSL_GeometryData（）'的引用
 build / libmessages_robocup_ssl_wrapper.pb.so：对`SSL_GeometryData :: default_instance（）'的引用未定义:: SerializeWithCachedSizesToArray（unsigned char *）const'
 build / libmessages_robocup_ssl_wrapper.pb.so：未定义对`SSL_GeometryData :: MergePartialFromCodedStream（google :: protobuf :: io :: CodedInputStream *）'的引用
 collect2： ld返回1个退出状态
 make [2]：** [clientTest]错误1 
 make [1]：** [CMakeFiles / clientTest.dir / all]错误2 
 make：* * [all] Erro 2 
  
我已经尝试了一段时间。 
如果 libmessages_robocup_ssl_wrapper.pb.so 为什么在链接之前已经构建，它会显示错误？
解决方案
很可能是链接顺序。
 
 
 
看起来像 messages_robocup_ssl_wrapper.pb 取决于 messages_robocup_ssl_geometry.pb 。如果是这样，包装程序应该在链接行中的几何体之前。
  target_link_libraries（clientTest robocup_ssl_client 
 messages_robocup_ssl_detection.pb 
 messages_robocup_ssl_wrapper.pb 
 messages_robocup_ssl_geometry.pb 
 messages_robocup_ssl_refbox_log.pb 
 netraw 
 robocup_ssl_client 
 protobu 
 netraw 
 robocup_ssl_client 
 protobu b  
更好的是，让CMake照顾这样的依赖项。
 
 
 
如果添加... 
  target_link_libraries（messages_robocup_ssl_wrapper.pb 
 messages_robocup_ssl_geometry.pb）
  
然后，当 messages_robocup_ssl_wrapper.pb 为CMake时，CMake将自动保留该依赖项。指定为另一个的依赖项目标。如果这样做，则可以选择从 target_link_libraries（clientTest ...）调用中省略 messages_robocup_ssl_geometry.pb  
 
I am working with the SSL-Vision software. It has an example client that I've been trying to separate from the whole project. I found the sources needed to edit a client myself, so I just copied them from the software and used CMake to build my client.

The project structure below is simplified, narrowing to the issue (I believe!).
.
├── CMakeLists.txt 
├── main.cc
├── build
│   ├── CMakeLists.txt
│   └── messages_ssl_... (.cc/.h, 4 each)
└── src
    ├── CMakeLists.txt
    └── (Other subdirs and sources/headers) 
./CMakeLists.txt:
cmake_minimum_required(VERSION 2.6)
project( TestClient )

find_package( PkgConfig REQUIRED )
pkg_check_modules( QTCORE_PKG QtCore )
include_directories( ${QTCORE_PKG_INCLUDE_DIRS} )

include(FindProtobuf)
find_package( Protobuf REQUIRED )
include_directories( ${PROTOBUF_INCLUDE_DIRS} )

find_package( PkgConfig REQUIRED )
pkg_check_modules( GLIB_PKG glib-2.0 ) 
include_directories( ${GLIB_PKG_INCLUDE_DIRS} )

include_directories( "src" ) 
add_subdirectory( src )

include_directories( "build" ) 
add_subdirectory( build )


add_executable( clientTest clientTest.cc )

target_link_libraries( clientTest robocup_ssl_client messages_robocup_ssl_detection.pb messages_robocup_ssl_geometry.pb messages_robocup_ssl_wrapper.pb messages_robocup_ssl_refbox_log.pb netraw robocup_ssl_client protobuf QtCore )
./build/CMakeLists.txt:
add_library( messages_robocup_ssl_detection.pb SHARED messages_robocup_ssl_detection.pb.cc )

add_library( messages_robocup_ssl_refbox_log.pb SHARED messages_robocup_ssl_refbox_log.pb.cc )

add_library( messages_robocup_ssl_geometry.pb SHARED messages_robocup_ssl_geometry.pb.cc )

add_library( messages_robocup_ssl_wrapper.pb SHARED messages_robocup_ssl_wrapper.pb.cc )
It could be a missing #include in the messages_ssl_... files, but they all are auto-generated and seems to be correct.

In messages_robocup_ssl_detection.pb.h and messages_robocup_ssl_detection.pb.h there are only protobuf includes.

In messages_robocup_ssl_refbox_log.pb.h:
#include "messages_robocup_ssl_detection.pb.h"
// Other protobuf includes
In messages_robocup_ssl_wrapper.h:
#include "messages_robocup_ssl_detection.pb.h"
#include "messages_robocup_ssl_geometry.pb.h"
// Other protobuf includes
In each .cc file is included only its header and other protobuf libs.

Finally, when I do make, the following error is generated:
Linking CXX executable clientTest
build/libmessages_robocup_ssl_wrapper.pb.so: undefined reference to `SSL_GeometryData::ByteSize() const'
build/libmessages_robocup_ssl_wrapper.pb.so: undefined reference to `SSL_GeometryData::MergeFrom(SSL_GeometryData const&)'
build/libmessages_robocup_ssl_wrapper.pb.so: undefined reference to `protobuf_AddDesc_messages_5frobocup_5fssl_5fgeometry_2eproto()'
build/libmessages_robocup_ssl_wrapper.pb.so: undefined reference to `SSL_GeometryData::Clear()'
build/libmessages_robocup_ssl_wrapper.pb.so: undefined reference to `SSL_GeometryData::SSL_GeometryData()'
build/libmessages_robocup_ssl_wrapper.pb.so: undefined reference to `SSL_GeometryData::default_instance()'
build/libmessages_robocup_ssl_wrapper.pb.so: undefined reference to `SSL_GeometryData::SerializeWithCachedSizesToArray(unsigned char*) const'
build/libmessages_robocup_ssl_wrapper.pb.so: undefined reference to `SSL_GeometryData::MergePartialFromCodedStream(google::protobuf::io::CodedInputStream*)'
collect2: ld returned 1 exit status
make[2]: ** [clientTest] Erro 1
make[1]: ** [CMakeFiles/clientTest.dir/all] Erro 2
make: ** [all] Erro 2
I've been trying to fix this for some time.
Why is the libmessages_robocup_ssl_wrapper.pb.so showing errors if it has already been built before the linkage?
解决方案
It could well be the linking order.

It looks like messages_robocup_ssl_wrapper.pb depends on messages_robocup_ssl_geometry.pb.  If so, wrapper should come before geometry in the link line.
target_link_libraries( clientTest robocup_ssl_client
                       messages_robocup_ssl_detection.pb
                       messages_robocup_ssl_wrapper.pb
                       messages_robocup_ssl_geometry.pb
                       messages_robocup_ssl_refbox_log.pb
                       netraw
                       robocup_ssl_client
                       protobuf
                       QtCore )
Even better, let CMake take care of dependencies like this.

If you add...
target_link_libraries( messages_robocup_ssl_wrapper.pb
                       messages_robocup_ssl_geometry.pb )
then CMake will automatically retain that dependency when messages_robocup_ssl_wrapper.pb is specified as a dependency of another target.  If you do this, then you can choose to omit messages_robocup_ssl_geometry.pb from the target_link_libraries( clientTest ... ) call.

                        
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