c++ - CMake:将依赖项添加到 IMPORTED 库

Question

我有一个供应商提供的库存档，我已将其导入到我的项目中:

add_library(
    lib_foo 
    STATIC 
    IMPORTED GLOBAL
    )

set_target_properties(
    lib_foo 
    PROPERTIES IMPORTED_LOCATION             
    "${CMAKE_CURRENT_LIST_DIR}/vendor/foo.a"
    )

set_target_properties(
    lib_foo 
    PROPERTIES INTERFACE_INCLUDE_DIRECTORIES 
    "${CMAKE_CURRENT_LIST_DIR}/vendor"
    )

当我尝试使用此库链接应用程序时，出现undefined reference to 'pthread_atfork' 链接器错误:

/usr/lib/libtcmalloc_minimal.a(libtcmalloc_minimal_internal_la-static_vars.o):
    In function `SetupAtForkLocksHandler':
    /tmp/gperftools-2.4/src/static_vars.cc:119: 
        undefined reference to `pthread_atfork'
        ../vendor/foo.a(platformLib.o): In function `foo::Thread::Impl::join()':

因此 vendor/foo.a 依赖于 pthread。

我尝试了 target_link_libraries(lib_foo pthread) 但它不起作用，因为 lib_foo 是一个IMPORTED 目标，而不是一个内置目标

CMake Error at libfoo/CMakeLists.txt:41 (target_link_libraries):
  Attempt to add link library "pthread" to target "lib_foo"
  which is not built in this directory.

问题:

如何将 pthread 链接到 lib_foo，或者指定依赖于 lib_foo 的目标也依赖于 pthread ?

Answer 1

IMPORTED_LINK_INTERFACE_LIBRARIES:

您可以设置一个额外的目标属性，IMPORTED_LINK_INTERFACE_LIBRARIES

Transitive link interface of an IMPORTED target.

Set this to the list of libraries whose interface is included when an IMPORTED library target is linked to another target.

The libraries will be included on the link line for the target.

Unlike the LINK_INTERFACE_LIBRARIES property, this property applies to all imported target types, including STATIC libraries.

set_target_properties(lib_foo 
    PROPERTIES IMPORTED_LINK_INTERFACE_LIBRARIES 
    pthread
    )

-pthread 编译器标志:

但是，在这种特殊情况中，pthread 链接问题，可以通过将-pthread 添加到您的编译器标志

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread" )

来自 man gcc:

-pthread Adds support for multithreading with the pthreads library. This option sets flags for both the preprocessor and linker.

它会导致文件用-D_REENTRANT 编译，并用-lpthread 链接。在其他平台上，这可能会有所不同。使用 -pthread 以获得大多数可移植性。

See this question for more information