我正在尝试使用FetchContent下载SDL2的预构建开发库。
因此,它们随后可以由FindSDL2.cmake模块拾取。
然而,目前我发现find_package在库下载之前就被执行了,这导致在定位SDL2时第一次干净的CMake构建失败。
但是,在第二次运行时,由于预构建库已经被缓存,因此SDL2位于第二次运行时。
关于如何确保在调用find_package之前已下载这些预构建库的任何建议
我的CMakeLists.txt文件。
cmake_minimum_required(VERSION 3.19.2)
project(racer VERSION 0.1.0)
# Racer
file(GLOB SOURCES src/*.cpp)
add_executable(${PROJECT_NAME} ${SOURCES})
# OpenGL
find_package(OpenGL REQUIRED)
target_include_directories(${PROJECT_NAME} PRIVATE ${OPENGL_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
# FindSDL2 Modules
list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/sdl2)
# Fetch Content Module
include(FetchContent)
# Visual C++
## SDL2
FetchContent_Declare(
SDL2
URL https://www.libsdl.org/release/SDL2-devel-2.0.14-VC.zip
URL_MD5 2b521c5ec247955dc342235d06ebd874
)
FetchContent_MakeAvailable(SDL2)
set(SDL2_PATH ${sdl2_SOURCE_DIR})
find_package(SDL2 REQUIRED)
target_include_directories(${PROJECT_NAME} PRIVATE ${SDL2_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARIES})
add_custom_command(TARGET racer POST_BUILD
COMMAND ${CMAKE_COMMAND} -E copy_directory
${sdl2_SOURCE_DIR}/lib/x64
$<TARGET_FILE_DIR:racer>)第一次运行日志。
[main] Configuring folder: racer
[proc] Executing command: "C:\Program Files\CMake\bin\cmake.EXE" --no-warn-unused-cli -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE -DCMAKE_BUILD_TYPE:STRING=Debug "-DCMAKE_C_COMPILER:FILEPATH=C:\Program Files\LLVM\bin\clang.exe" "-DCMAKE_CXX_COMPILER:FILEPATH=C:\Program Files\LLVM\bin\clang++.exe" -Hc:/Users/Josh/projects/racer -Bc:/Users/Josh/projects/racer/build -G "Unix Makefiles"
[cmake] Not searching for unused variables given on the command line.
[cmake] -- The C compiler identification is Clang 12.0.0 with GNU-like command-line
[cmake] -- The CXX compiler identification is Clang 12.0.0 with GNU-like command-line
[cmake] -- Detecting C compiler ABI info
[cmake] -- Detecting C compiler ABI info - done
[cmake] -- Check for working C compiler: C:/Program Files/LLVM/bin/clang.exe - skipped
[cmake] -- Detecting C compile features
[cmake] -- Detecting C compile features - done
[cmake] -- Detecting CXX compiler ABI info
[cmake] -- Detecting CXX compiler ABI info - done
[cmake] -- Check for working CXX compiler: C:/Program Files/LLVM/bin/clang++.exe - skipped
[cmake] -- Detecting CXX compile features
[cmake] -- Detecting CXX compile features - done
[cmake] -- Found OpenGL: opengl32
[cmake] CMake Error at C:/Program Files/CMake/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:218 (message):
[cmake] Could NOT find SDL2 (missing: SDL2_LIBRARY SDL2_INCLUDE_DIR)
[cmake] Call Stack (most recent call first):
[cmake] C:/Program Files/CMake/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:582 (_FPHSA_FAILURE_MESSAGE)
[cmake] cmake/sdl2/FindSDL2.cmake:313 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
[cmake] CMakeLists.txt:29 (find_package)
[cmake]
[cmake]
[cmake] -- Configuring incomplete, errors occurred!
[cmake] See also "C:/Users/Josh/projects/racer/build/CMakeFiles/CMakeOutput.log".
[cmake] See also "C:/Users/Josh/projects/racer/build/CMakeFiles/CMakeError.log".第二次运行日志(不清除build目录)。
[main] Configuring folder: racer
[proc] Executing command: "C:\Program Files\CMake\bin\cmake.EXE" --no-warn-unused-cli -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE -DCMAKE_BUILD_TYPE:STRING=Debug "-DCMAKE_C_COMPILER:FILEPATH=C:\Program Files\LLVM\bin\clang.exe" "-DCMAKE_CXX_COMPILER:FILEPATH=C:\Program Files\LLVM\bin\clang++.exe" -Hc:/Users/Josh/projects/racer -Bc:/Users/Josh/projects/racer/build -G "Unix Makefiles"
[cmake] Not searching for unused variables given on the command line.
[cmake] -- Found SDL2: C:/Users/Josh/projects/racer/build/_deps/sdl2-src/lib/x64/SDL2.lib (found version "2.0.14")
[cmake] CMake Warning (dev) at C:/Program Files/CMake/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:426 (message):
[cmake] The package name passed to `find_package_handle_standard_args` (SDL2main)
[cmake] does not match the name of the calling package (SDL2). This can lead to
[cmake] problems in calling code that expects `find_package` result variables
[cmake] (e.g., `_FOUND`) to follow a certain pattern.
[cmake] Call Stack (most recent call first):
[cmake] cmake/sdl2/FindSDL2.cmake:318 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
[cmake] CMakeLists.txt:29 (find_package)
[cmake] This warning is for project developers. Use -Wno-dev to suppress it.
[cmake]
[cmake] -- Found SDL2main: C:/Users/Josh/projects/racer/build/_deps/sdl2-src/lib/x64/SDL2main.lib (found version "2.0.14")
[cmake] -- Configuring done
[cmake] -- Generating done
[cmake] -- Build files have been written to: C:/Users/Josh/projects/racer/build发布于 2021-06-24 08:09:59
我认为您需要在第一个project()调用之前做好所有的FetchContent工作。然后在调用project()之后调用find_package()。
文档中没有明确介绍,但是有一个指定使用工具链文件的示例,即使工具链文件是通过FetchContent下载的:https://cmake.org/cmake/help/latest/module/FetchContent.html#examples
未经测试,但可能:
cmake_minimum_required(VERSION 3.19.2)
# Fetch Content Module
include(FetchContent)
# Visual C++
## SDL2
FetchContent_Declare(
SDL2
URL https://www.libsdl.org/release/SDL2-devel-2.0.14-VC.zip
URL_MD5 2b521c5ec247955dc342235d06ebd874
)
FetchContent_MakeAvailable(SDL2)
set(SDL2_PATH ${sdl2_SOURCE_DIR})
project(racer VERSION 0.1.0)
# Racer
file(GLOB SOURCES src/*.cpp)
add_executable(${PROJECT_NAME} ${SOURCES})
# OpenGL
find_package(OpenGL REQUIRED)
target_include_directories(${PROJECT_NAME} PRIVATE ${OPENGL_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} ${OPENGL_LIBRARIES})
# FindSDL2 Modules
list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/sdl2)
find_package(SDL2 REQUIRED)
target_include_directories(${PROJECT_NAME} PRIVATE ${SDL2_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARIES})
add_custom_command(TARGET racer POST_BUILD
COMMAND ${CMAKE_COMMAND} -E copy_directory
${sdl2_SOURCE_DIR}/lib/x64
$<TARGET_FILE_DIR:racer>)https://stackoverflow.com/questions/67356549
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