本征cmake要求使用“ target_link_libraries”即使仅模板 [英] Eigen cmake requires "target_link_libraries" even though it's template-only

问题描述

在Eigen库的官方cmake文档中，它需要以下行：$code> target_link_libraries（例如Eigen3 :: Eigen）。我尝试删除该行，但是随后编译将失败，并显示未找到本征。

In Eigen library's official cmake doc, it requires the line target_link_libraries (example Eigen3::Eigen). I have tried removing that line, but then the compilation would fail with "Eigen not found".

这直接与另一个StackOverflow问题中的讨论相矛盾：在我的Cmake项目中使用Eigen Lib吗？

This directly contradicts the discussion in another StackOverflow question: Using Eigen Lib in my Cmake project?

我不明白为什么Eigen需要 target_link_libraries 即使是仅模板的库？就像上面的StackOverflow问题一样，我假设我只需要包含Eigen标头（ include_directories（）），它就可以直接使用。没错

I don't understand why Eigen would need target_link_libraries even though it's a template-only library? Just like the above StackOverflow question, I'd assume I only have to include the Eigen headers (include_directories()) and it should work out of the box. It doesn't.

推荐答案

啊，我现在知道发生了什么：CMake中有一个称为接口库的概念实际上并没有建立一个库二进制文件。它是专为像Eigen这样的仅模板库而设计的。

Ah now I know what's going on: there's a concept called "interface library" in CMake that doesn't actually build a library binary. It is designed precisely for template-only libraries like Eigen.

参考文献：
- https://cmake.org/cmake/help/latest/command/add_library.html#interface-libraries
- http://mariobadr.com/creating-a-header-only-library-with-cmake.html

希望这可以帮助其他挣扎cmake的人！

Hope this helps other souls struggling with cmake!

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