CMake的static_directory问题与静态库（在Mac OS X上） [英] CMake's link_directories issue with static library (on Mac OS X)

问题描述

我在/ PATH目录中有一个静态库，当我试图使用 link_directories 的库如下：

I have a static library in /PATH directory, and when I tried to use the library with link_directories as follows:

link_directories(/PATH)
target_link_libraries(CppHello libHelloLib.a)

我有一个错误消息：

ld: library not found for -lHelloLib
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[3]: *** [/PATH] Error 1
make[2]: *** [CMakeFiles/CppHello.dir/all] Error 2
make[1]: *** [CMakeFiles/CppHello.dir/rule] Error 2

相反，我必须指定如下路径才能使其工作：

Instead, I had to specify the path as follows to make it work:

target_link_libraries(CppHello /PATH/libHelloLib.a)

可能有什么问题？这是Cmake在Mac OS X上的问题，或者我只是错过了什么？

What might be wrong? Is this an issue with Cmake on Mac OS X, or did I just miss something?

推荐答案

在 link_directories（） >创建可执行文件： link_directories 仅影响在其后创建的目标： https://cmake.org/cmake/help/v3.4/command/link_directories.html 。结果是，将正确的 -lHelloLib 标志添加到目标，但是lib搜索路径未更新为 -L / PATH 。

You call link_directories() after creating executable: link_directories affects only on targets, created after it: https://cmake.org/cmake/help/v3.4/command/link_directories.html. The result is that the correct -lHelloLib flag is added to the target, but the lib search path isn't updated with a -L/PATH flag.

在创建任何目标之前，请调用 link_directories（）

Instead put the call to link_directories() before you create any targets.

自从3.3版本CMake文档 target_link_libraries 明确指定了它接受的链接的哪种类型的项目。其中：

Since 3.3 version CMake documentation for target_link_libraries explicitely specifies, which kind of items for link it accepts. Among them:

• 库文件的完整路径


• >
  

• A full path to a library file
• A plain library name

因此，您应该指定库文件的完整路径或 / strong>，没有文件扩展名（ .a ）和前缀（ lib ）。在这种情况下，错误信息显示，CMake试图处理甚至只有文件名库，但没有成功（某种类型的未定义行为）。

So, you should specify either full path to the library file, or only name for the library, without file's extension(.a) and prefix(lib). Error message in you case shows, that CMake has tried to handle even filename-only library, but without success(some sort of Undefined Behaviour).

虽然以前的CMake版本没有记录这个命令清楚，他们可能遵循相同的约定。

While previous versions of CMake doesn't document this command so clear, they, probably, follow same convention.

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