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Accepted
SGriffeth
Asked: 2024-04-08 03:14:02 +0800 CST

如何找到保存包路径的 cmake 变量

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假设我使用了 find_package(SDL REQUIRED)，现在我需要通过 target_link_libraries 链接到该库，要传递给 target_link_libraries 的变量名称是什么？一般来说，除了启发式猜测之外，还有其他方法可以找到这些变量吗？我尝试过 SDL_LIBRARY、SDL2_LIBRARY 和 SDL_LIBRARIES。我确实安装了 sdl2。

我本以为这会起作用，但它没有：

cmake_minimum_required(VERSION 3.10)
project(someProject)

# Find SDL2
find_package(SDL REQUIRED)
find_package(SDL_image REQUIRED)

# Include directories
include_directories(${SDL2_INCLUDE_DIRS} ${SDL2_IMAGE_INCLUDE_DIRS})

# Set source files
set(SOURCES main.cpp)

# Set executable
add_executable(someProject ${SOURCES})

# Link libraries
target_link_libraries(someProject ${SDL2_LIBRARIES} ${SDL2_IMAGE_LIBRARIES})

> CMake Error at
> /usr/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:230
> (message):   Could NOT find SDL (missing: SDL_LIBRARY SDL_INCLUDE_DIR)
> Call Stack (most recent call first):  
> /usr/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:600
> (_FPHSA_FAILURE_MESSAGE)   /usr/share/cmake/Modules/FindSDL.cmake:224
> (FIND_PACKAGE_HANDLE_STANDARD_ARGS)   CMakeLists.txt:5 (find_package)
> 
> 
> -- Configuring incomplete, errors occurred!
cmake

1 个回答

  1. Best Answer

    通常 是<MODULENAME>_LIBRARIES这样，SDL 也是如此。

    但这只是约定，您可能需要阅读相应的find_<MODULENAME>.cmake脚本（通常在 /usr/share/cmake/Modules、/usr/lib/cmake/version/Modules 或源树的一部分等位置）。遗憾的是，尤其是在连字符、大写和其他命名细微差别方面，这些 CMake 模块简直就是狂野西部。您要么从库作者那里获得良好的文档，要么需要阅读find_<MODULENAME>.cmake.

    也不是说您不应该使用在 CMake 中使用库的旧方法。而不是你的

    # Find SDL2
find_package(SDL REQUIRED)
find_package(SDL_image REQUIRED)

# Include directories
include_directories(${SDL2_INCLUDE_DIRS} ${SDL2_IMAGE_INCLUDE_DIRS})

# Set source files
set(SOURCES main.cpp)

# Set executable
add_executable(someProject ${SOURCES})

# Link libraries
target_link_libraries(someProject ${SDL2_LIBRARIES} ${SDL2_IMAGE_LIBRARIES})

    你应该只使用现代的 CMake，这会让事情变得简单。如果你只需要SDL2（而不是SDL2_image），那么你的整个发现和使用就变成这样：

    # Find SDL2, which has modern CMake bindings
find_package(SDL REQUIRED)

# SDL_image is legacy, so that's annoying, we have to fix things ourselves:
find_package(SDL_image REQUIRED)

# Set executable
add_executable(someProject main.cpp)

# Link libraries (I assume you want PRIVATE here, `someProject` is not supposed to export SDL targets/symbols)
target_link_libraries(someProject PRIVATE SDL::SDL)

    您不必自己设置包含目录，它们会自动设置，因为您将目标链接SDL::SDL到Find_SDL.cmake.

    然而，您需要SDL2_image（您确定吗？我认为现在它是 SDL 的一部分，但我可能是错的），而这并没有得到太多的喜爱，所以我们需要自己进行现代 CMake 设置。优点是我们只执行一次，从那时起，我们总是可以只使用我们设置的一次目标，而不必摆弄target_include_…东西。

    # Find SDL2, which has modern CMake bindings
find_package(SDL REQUIRED)

# SDL_image is legacy, so that's annoying, we have to fix things ourselves:
find_package(SDL_image REQUIRED)
if(NOT TARGET SDL::image)
  add_library(SDL::image INTERFACE IMPORTED)
  set_target_properties(SDL::image PROPERTIES
     INTERFACE_INCLUDE_DIRECTORIES "${SDL_IMAGE_INCLUDE_DIRS}"
     INTERFACE_LINK_LIBRARIES "${SDL_IMAGE_LIBRARIES}")
endif()

# Set executable
add_executable(someProject main.cpp)

# Link libraries 
target_link_libraries(someProject PRIVATE SDL::SDL SDL::image)

    就是这样; 无需记住多个变量名称，只需记住链接目标的名称：SDL::SDL以及我们自己的SDL::image.

    • 1

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