如何指定 OBJECT 库的导入依赖项? [英] How to specify imported dependencies of an OBJECT library?

问题描述

我有一个 OBJECT 库 objlib，它链接到主要目标 maintarget.objlib 有一个依赖库，比如 ZLIB.如果我们使用旧的 _* 变量，那么这很容易:

I have an OBJECT library objlib which is linked into the main target maintarget. The objlib has a dependent library, say, ZLIB. If we're using the legacy <package-name>_* variables then it's easy:

add_library(objlib OBJECT ...)
target_include_directories(objlib ${ZLIB_INCLUDE_DIRS})
...
add_executable(maintarget $<TARGET_OBJECTS:objlib>)
target_link_libraries(maintarget ${ZLIB_LIBRARIES})

但我想将依赖项用作 IMPORTED 库，因为它更简洁(以及创建配置模块的便捷方式，即使用 install(EXPORT ...)，就是这样做的).

But I want to use the dependency as an IMPORTED library because it's more concise (and the convenient way to create config modules, that is, using install(EXPORT ...), does just that).

以下代码不起作用，因为 target_link_libraries 不能与 OBJECT 库一起使用:

The following code does not work because target_link_libraries cannot be used with an OBJECT library:

add_library(objlib OBJECT ...)
target_link_libraries(objlib ZLIB::ZLIB)

将 ZLIB::ZLIB 链接到 maintarget 也不起作用，objlib 没有获得包含目录:

Linking ZLIB::ZLIB to maintarget does not work either, objlib does not get the include directories:

add_library(objlib OBJECT ...)
...
add_executable(maintarget $<TARGET_OBJECTS:objlib>)
target_link_libraries(maintarget ZLIB::ZLIB)

使用中间 INTERFACE 库 (objlib-wrapper) 进行黑客攻击也不起作用.

Hacking with an intermediate INTERFACE library (objlib-wrapper) does not work either.

唯一有效的是查询 IMPORTED 库的属性并重新生成通常在 _* 变量中可用的信息.这是一个令人讨厌的解决方法.

The only thing that works is to query the IMPORTED library's properties and regenerate the information normally available in the <package-name>_* variables. Which is a nasty workaround.

有更好的方法吗?

推荐答案

从 CMake 3.12 开始，您现在可以在对象库上使用 target_link_libraries 来获取使用要求.

As of CMake 3.12, you can now use target_link_libraries on object libraries to get usage requirements.

使用 3.12，您提到的这种方法应该可行:

Using 3.12, this approach that you mentioned should work:

add_library(objlib OBJECT ...)
target_link_libraries(objlib ZLIB::ZLIB)

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