链接时出现 CMake PUBLIC / INTERFACE 问题

Question

我在 CMake 和链接/编译我正在处理的项目的一部分方面遇到了问题。

目标的文件夹结构如下：

── sleeptimer
    ├── config
    │   └── sl_sleeptimer_config.h
    ├── inc
    │   └── sl_sleeptimer.h
    └── src
        ├── sl_sleeptimer.c
        ├── sl_sleeptimer_hal.h
        ├── sl_sleeptimer_hal_prortc.c
        ├── sl_sleeptimer_hal_rtc.c
        └── sl_sleeptimer_hal_rtcc.c

应添加此内容的 CMake 文件如下所示：

project(service)

add_library(${PROJECT_NAME}
        sleeptimer/src/sl_sleeptimer.c)

target_include_directories(${PROJECT_NAME} PUBLIC
        sleeptimer/config
        sleeptimer/inc
        sleeptimer/src)

target_link_libraries(${PROJECT_NAME} common_platform emlib)

但我在链接时遇到错误：

platform/service/libservice.a(sl_sleeptimer.c.obj): In function `sl_sleeptimer_init':
/mnt/c/Users/username/Downloads/_test/gecko_sdk/platform/service/sleeptimer/src/sl_sleeptimer.c:152: undefined reference to `sleeptimer_hal_init_timer'
/mnt/c/Users/username/Downloads/_test/gecko_sdk/platform/service/sleeptimer/src/sl_sleeptimer.c:153: undefined reference to `sleeptimer_hal_enable_int'
/mnt/c/Users/username/Downloads/_test/gecko_sdk/platform/service/sleeptimer/src/sl_sleeptimer.c:154: undefined reference to `sleeptimer_hal_get_timer_frequency'
platform/service/libservice.a(sl_sleeptimer.c.obj): In function `sl_sleeptimer_stop_timer':
/mnt/c/Users/username/Downloads/_test/gecko_sdk/platform/service/sleeptimer/src/sl_sleeptimer.c:313: undefined reference to `sleeptimer_hal_disable_int'
platform/service/libservice.a(sl_sleeptimer.c.obj): In function `sl_sleeptimer_get_tick_count':
/mnt/c/Users/username/Downloads/_test/gecko_sdk/platform/service/sleeptimer/src/sl_sleeptimer.c:428: undefined reference to `sleeptimer_hal_get_counter'
platform/service/libservice.a(sl_sleeptimer.c.obj): In function `set_comparator_for_next_timer':
/mnt/c/Users/username/Downloads/_test/gecko_sdk/platform/service/sleeptimer/src/sl_sleeptimer.c:1091: undefined reference to `sleeptimer_hal_enable_int'
/mnt/c/Users/username/Downloads/_test/gecko_sdk/platform/service/sleeptimer/src/sl_sleeptimer.c:1092: undefined reference to `sleeptimer_hal_set_compare'
platform/service/libservice.a(sl_sleeptimer.c.obj): In function `update_first_timer_delta':
/mnt/c/Users/username/Downloads/_test/gecko_sdk/platform/service/sleeptimer/src/sl_sleeptimer.c:1100: undefined reference to `sleeptimer_hal_get_counter'

所有未定义的函数都在sl_sleeptimer_hal.h 中声明。

我有点迷茫，因为我或多或少刚刚开始学习 make / CMake。

Answer 1

我认为问题在于您没有添加所有源文件。 我还添加了一些建议。默认为 PRIVATE，除非你知道你需要 PUBLIC/INTERFACE。

# Your project and your targets should never have the same name btw
project(SERVICE
 LANGUAGES C
)

add_library(service)

# Add all your source files
target_sources(service PRIVATE 
    sleeptimer/src/sl_sleeptimer.c
    sleeptimer/src/sl_sleeptimer_hal_prortc.c
    sleeptimer/src/sl_sleeptimer_hal_rtc.c
    sleeptimer/src/sl_sleeptimer_hal_rtcc.c
)

# EDIT:
# You probably want 1 or all of these to be PUBLIC depending on your circumstances.
target_include_directories(service 
# Clients don't need to know these include directories exist
PRIVATE
    sleeptimer/config
    sleeptimer/src

# Both service and clients that link against service need this include directory
PUBLIC
    sleeptimer/inc
)

target_link_libraries(service PRIVATE common_platform emlib)

编辑：

PRIVATE/INTERFACE/PUBLIC的基本解释：

PRIVATE 意味着只有目标服务可以看到它。 INTERFACE 表示只有链接到服务的目标才能看到它。 PUBLIC 是 PRIVATE/INTERFACE 的组合。

INTERFACE 通常只用于只有头文件的库，或者非常特殊的情况。

要获得真正深入的解释，我建议使用 Professional CMake： 实用指南 (https://crascit.com/professional-cmake/)