如何让CMake找到OpenMP_C、OpenMP_CXX等？

Question

我对终端的工作相当陌生，我正在尝试使用cmake为一个涉及公共交通路线的项目配置构建。当我尝试进行构建时，我在终端中得到了以下响应：

$ cmake ..
-- Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS OpenMP_C_LIB_NAMES) 
-- Could NOT find OpenMP_CXX (missing: OpenMP_CXX_FLAGS OpenMP_CXX_LIB_NAMES) 
-- Could NOT find OpenMP (missing: OpenMP_C_FOUND OpenMP_CXX_FOUND) 
CMake Warning at CMakeLists.txt:33 (message):
  Configuring without OpenMP!


CMake Error at src/CMakeLists.txt:13 (add_subdirectory):
  The source directory

    /Users/ericbush/Desktop/the-one/toolkit/gtfs/pfaedle/src/cppgtfs

  does not contain a CMakeLists.txt file.


CMake Error at src/CMakeLists.txt:14 (add_subdirectory):
  The source directory

    /Users/ericbush/Desktop/the-one/toolkit/gtfs/pfaedle/src/configparser

  does not contain a CMakeLists.txt file.


-- Configuring incomplete, errors occurred!
See also "/Users/ericbush/Desktop/the-one/toolkit/gtfs/pfaedle/build/CMakeFiles/CMakeOutput.log".
See also "/Users/ericbush/Desktop/the-one/toolkit/gtfs/pfaedle/build/CMakeFiles/CMakeError.log".

下面是我认为是来自CMakeLists.txt文件的相关代码：

find_package(OpenMP)

if (OPENMP_FOUND)
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
endif()


# set compiler flags, see http://stackoverflow.com/questions/7724569/debug-vs-release-in-cmake
if(OPENMP_FOUND)
    set(CMAKE_CXX_FLAGS            "-fopenmp -Ofast -fno-signed-zeros -fno-trapping-math -Wall -Wno-format-extra-args -Wextra -Wformat-nonliteral -Wformat-security -Wformat=2 -Wextra -Wno-implicit-fallthrough -pedantic")
else()
    message(WARNING "Configuring without OpenMP!")
    set(CMAKE_CXX_FLAGS            "-Ofast -fno-signed-zeros -fno-trapping-math -Wall -Wno-format-extra-args -Wextra -Wformat-nonliteral -Wformat-security -Wformat=2 -Wextra -Wno-implicit-fallthrough -pedantic")
endif()
set(CMAKE_CXX_FLAGS_DEBUG          "-Og -g -DLOGLEVEL=3 -DPFAEDLE_DBG=1")
set(CMAKE_CXX_FLAGS_MINSIZEREL     "${CMAKE_CXX_FLAGS} -DLOGLEVEL=2")
set(CMAKE_CXX_FLAGS_RELEASE        "${CMAKE_CXX_FLAGS} -DLOGLEVEL=2")
set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS} -g -DLOGLEVEL=3")

我在这个和其他网站上发现了一些类似的问题，但我仍然在努力理解这个问题，因为我以前从未使用过cmake，而且，正如前面提到的，我对终端的工作有些陌生。我非常感谢任何关于错误消息实际告诉我的信息，或者任何关于我可以采取的步骤/我可以尝试解决问题的建议。我正在Mac上工作，如果有人想知道的话。

Answer 1

为了让编译器看到OpenMP，您可能需要在cmake命令中设置以下选项(对于位于/opt/local中的依赖项)：

cmake .. -DOpenMP_C_FLAGS=-fopenmp=lomp -DOpenMP_CXX_FLAGS=-fopenmp=lomp -DOpenMP_C_LIB_NAMES="libomp" -DOpenMP_CXX_LIB_NAMES="libomp" -DOpenMP_libomp_LIBRARY="/opt/local/lib/libomp.dylib" -DOpenMP_CXX_FLAGS="-Xpreprocessor -fopenmp /opt/local/lib/libomp.dylib -I/opt/local/include" -DOpenMP_CXX_LIB_NAMES="libomp" -DOpenMP_C_FLAGS="-Xpreprocessor -fopenmp /opt/local/lib/libomp.dylib -I/opt/local/include"

缺少的两个CMakeLists.txt位于src/的git子模块中，要下载子模块，请使用cd将其下载到根phaedle目录，然后发出以下命令：

git submodule update --init --recursive

编辑:这个问题现在在master中得到了修复。