我如何链接包含基于CMAKE定义的全局变量定义的条件类型/变量定义的库？
简介
我正在尝试使用 toulbar2 作为我的CMAKE项目中的C ++库，但是我有很多麻烦将其链接到我的主要可执行文件。
我在此处和其他类似网站上都发现了许多有关此主题的类似问题，但是它们都没有帮助我解决我的具体问题。我实际上尝试了所有事情，但我没有让它起作用，我希望你们中的一些人可以帮助我。
我正在运行Ubuntu 18.04，CMAKE版本3.23，在我的项目中，我正在使用标准C ++ 11。我是一名熟练的程序员，但我只是C ++和CMAKE的初学者/中级用户。
我已经尝试做的事情
我无法列出我的所有尝试，所以我只会提及我认为是我最好的尝试，以使您了解我可能做错了什么。
1）在我的第一次尝试中，我尝试使用与我导入的任何非标准库相同的方法，即使用find_package（）在cmakelists.txt中链接找到的库，并包含找到的include_dirs。但是，我很快意识到Toulbar2均未提供A find＆lt; tokage＆gt; .cmake或＆lt; name＆gt; config.cmake file。因此，这种方法无法正常工作。
2）我的第二次尝试是我认为使我最接近解决方案的尝试。您可以使用命令来轻松地将Toulbar2作为动态库来编译：cmake -dlibtb2 = on ..在您先前创建的假设 build> build> build>中。使用构造后，您的.so文件中的build> build/lib/linux。安装后，您可以使用命令find_library本身使Cmake本身找到此库。因此，我的cmakelists.txt最终看起来像这样：
[...]
find_library(TB2_LIBRARIES tb2)
if(TB2_LIBRARIES)
set(all_depends ${all_depends} ${TB2_LIBRARIES})
else(TB2_LIBRARIES)
add_compile_definitions("-DNO_TB2")
message("Compiling without Toulbar2, if you want to use it, please install it first")
endif(TB2_LIBRARIES)
[...]
target_link_libraries(main ${all_depends})
[...]
此代码在某种程度上起作用，这意味着cmake正确地找到了库并运行链接命令，但是，如果我尝试#include #include＆lt; toulbar2lib.hpp＆gt; 找不到标题。因此，我发现我应该告诉CMAKE在哪里可以找到该标头，所以我最终添加了一个
include_directories(/path/to/header/file's/directory)
，但是我还有另一个问题。找到标头，但是在编译时找不到许多标题中使用的名称。原因是在Toulbar2中，通过使用#IFDEF或#IFNDEF等预处理指令来有条件地定义某些变量/类型，并且依次通过在编译时通过CMAKE定义了这些条件中使用的全局变量。如果您对一个示例感兴趣，我可以提及提到的标头文件中使用的COPT类型。我看到这里的难题中缺少一块，但我无法弄清楚哪一个。由于我预先编译了库，这些定义在包含标头文件时应该存在，因为我正确地链接了包含这些定义的通讯库。
3）我的第三次尝试不如我提到的其他两个尝试优雅，但我拼命地试图找到解决方案。因此，我在项目中复制了整个Toulbar2克隆文件夹，并尝试将其添加为子目录，这意味着我的主cmakelists.txt包含该行：
add_subdirectory(toulbar2)
它提供cmakelists.txt < /code>也是如此，这样做应该没有问题。然后，我包括包含我需要的标头文件的Toulbar2的SRC目录，我应该没事。正确的？错误的。我遇到了与以前相同的问题（2），即当我尝试编译项目时，实际上并未定义一些有条件定义的变量/类型，即使副标题Toulbar2正确（无错误）。
我只想提到任何答案是欢迎的，但是，如果您可以帮助我找出一个优雅的解决方案（请参阅1或2），这将会更好，因为此代码将很快或以后发布。预先感谢您的帮助。
Introduction
I am trying to use Toulbar2 as a C++ library in my CMake project, however I am having much trouble linking it to my main executable.
I found many similar questions on this topic, both here and on other similar website, but none of them helped me with my specific issue. I tried literally everything and I did not menage to make it work, I was hoping that some of you may help me with that.
I am running Ubuntu 18.04, CMake version 3.23 and in my project I am using the standard C++11. I am a proficient programmer, but I am just an beginner/intermediate user of both C++ and CMake.
What I've already tried to do
I cannot list all my attempts, so I will only mention those I think are my best ones, to give you an idea of what I may be doing wrong.
1) In my first attempt, I tried to use the same approach I used for any non-standard library I imported, i.e. using find_package() in CMakeLists.txt to then link the found LIBRARIES and include the found INCLUDE_DIRS. However, I soon realised that Toulbar2 provides neither a Find<package>.cmake or <name>Config.cmake file. So, this approach could not work.
2) My second attempt is the one that in my opinion brought me the closest to the solution I hoped for. You can easily compile Toulbar2 as a dynamic library using the command: cmake -DLIBTB2=ON .. in an hypothetical build directory you previously created. After compiling with make you have your .so file in build/lib/Linux. After installation, you can make CMake find this library by itself using the command find_library. So, my CMakeLists.txt ended up looking like this:
[...]
find_library(TB2_LIBRARIES tb2)
if(TB2_LIBRARIES)
set(all_depends ${all_depends} ${TB2_LIBRARIES})
else(TB2_LIBRARIES)
add_compile_definitions("-DNO_TB2")
message("Compiling without Toulbar2, if you want to use it, please install it first")
endif(TB2_LIBRARIES)
[...]
target_link_libraries(main ${all_depends})
[...]
This code works to some extent, meaning that CMake correctly finds the library and runs the linking command, however if I try to #include <toulbar2lib.hpp> the header is not found. So I figured out I should have told CMake where to find that header, so I ended up adding a
include_directories(/path/to/header/file's/directory)
However, I still have another problem. The header is found, but a lot of names used in the header are not found at compilation time. The reason is that in Toulbar2 some variables/types are defined conditionally by using preprocessing directives like #ifdef or #ifndef, and in turn the global variables used in these conditions are defined through CMake at compilation time. If you are interested in an example, I can mention the Cost type that is used in the mentioned header file. I see that there's a piece missing in the puzzle here, but I cannot figure out which one. Since I pre-compiled the library those definitions should exist when I include the header file, because I am correctly linking the correspondent library that contains those definitions.
3) My third attempt is less elegant than the the other two I mentioned, but I was desperately trying to find a solution. So, I copied the whole toulbar2 cloned folder inside my project and I tried to add it as a subdirectory, meaning that my main CMakeLists.txt contains the line:
add_subdirectory(toulbar2)
It provides a CMakeLists.txt too, there should be no problem in doing it. Then I include the src directory of toulbar2, that contains the header file I need, and I should be okay. Right? Wrong. I got the same problem that I had before with (2), i.e. some variables/types conditionally defined were not actually defined when I tried to compile my project, even though the subproject toulbar2 was correctly (no errors) compiled.
I just wanted to mention that any answer is welcome, however if you could help me figure out an elegant solution (see 1 or 2) for this problem it would be way better, as this code is intended to be published soon or later. Thank you in advance for your help.
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评论（1）
解决方案2）看起来不错。您只需要添加以下汇编标志-dndebug -dboost -dlongdouble_prob -dlong_cost使用toulbar2lib.hpp编译项目时。请参阅github/toulbar2 readme.md如何在没有cmake的情况下编译这些标志（除了在这种情况下不应通过使用的wcspformatly）。
Solution 2) looks fine. You just need to add the following compilation flags -DNDEBUG -DBOOST -DLONGDOUBLE_PROB -DLONGLONG_COST when compiling your project with toulbar2lib.hpp. See github/toulbar2 README.md how to compile without cmake for those flags (except WCSPFORMATONLY that should not by used in this context).