使用cmake构建错误:找不到-lpthreads

Question

我有一个在给定机器上顺利运行的c ++项目,现在我正在尝试使用相同的操作系统(Xubuntu 14.04)在另一个上编译它.

我已经安装了所有的依赖项,我使用cmake来构建项目,尽管它因以下错误而停止:

确定pthreads中是否存在函数pthread_create失败,输出如下:.../usr/bin/ld:找不到-lpthreads

包含编译器标志的cmakelists.txt行如下:

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O3 -lpthread -DNDEBUG -DEIGEN_MPL2_ONLY")
set(CMAKE_C_FLAGS_DEBUG "-g -O0 -Wall -lpthread -DEIGEN_MPL2_ONLY")
set(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS} -O3 -lpthread -I/usr/include/freetype2 -DNDEBUG -DEIGEN_MPL2_ONLY")
set(CMAKE_CXX_FLAGS_DEBUG "-g -O0 -Wall -lpthread -I/usr/include/freetype2 -DEIGEN_MPL2_ONLY")

我做了一些研究,已经尝试过以下方法:

-used -pthread/-threads/-thread/-lpthreads而不是-lpthread,它不能解决问题并使构建停止而不会找到以下包: find_package (Threads)

• 在上面的cmakelists行中更改了-lpthread的顺序,这会产生相同的错误
• 使用了不同的版本o gcc/g ++:试过4.4,4.6和4.8,没有任何改变
• 在/ usr/lib /中创建了一个指向libpthread.so的符号链接,没有任何更改

我会很感激一些帮助,因为我已经很想知道下一步该尝试什么.

编辑1

图书馆应该在哪里:

$ find /lib -name "*pthread*"
/lib/x86_64-linux-gnu/libpthread-2.19.so
/lib/x86_64-linux-gnu/libpthread.so.0

还发现了pthread_create:

$ nm /lib/x86_64-linux-gnu/libpthread.so.0 | grep "pthread_create"
0000000000008430 t __pthread_create_2_1
00000000000081430 T pthread_create@@GLIBC_2.2.5

我还验证了libpthread-stubs0和libc6-dev都存在.

编辑2

这是FindThreads.cmake文件内容的一部分,位于/usr/share/cmake-2.8/Modules/中:

if(CMAKE_HAVE_SPROC_H AND NOT CMAKE_THREAD_PREFER_PTHREAD)
  # We have sproc
  set(CMAKE_USE_SPROC_INIT 1)
else()
  # Do we have pthreads?
  CHECK_INCLUDE_FILES("pthread.h" CMAKE_HAVE_PTHREAD_H)
  if(CMAKE_HAVE_PTHREAD_H)

    #
    # We have pthread.h
    # Let's check for the library now.
    #
    set(CMAKE_HAVE_THREADS_LIBRARY)
    if(NOT THREADS_HAVE_PTHREAD_ARG)
      # Check if pthread functions are in normal C library
      CHECK_SYMBOL_EXISTS(pthread_create pthread.h CMAKE_HAVE_LIBC_CREATE)
      if(CMAKE_HAVE_LIBC_CREATE)
        set(CMAKE_THREAD_LIBS_INIT "")
        set(CMAKE_HAVE_THREADS_LIBRARY 1)
        set(Threads_FOUND TRUE)
      endif()

      if(NOT CMAKE_HAVE_THREADS_LIBRARY)
        # Do we have -lpthreads
        CHECK_LIBRARY_EXISTS(pthreads pthread_create "" CMAKE_HAVE_PTHREADS_CREATE)
        if(CMAKE_HAVE_PTHREADS_CREATE)
          set(CMAKE_THREAD_LIBS_INIT "-lpthreads")
          set(CMAKE_HAVE_THREADS_LIBRARY 1)
          set(Threads_FOUND TRUE)
        endif()

        # Ok, how about -lpthread
        CHECK_LIBRARY_EXISTS(pthread pthread_create "" CMAKE_HAVE_PTHREAD_CREATE)
        if(CMAKE_HAVE_PTHREAD_CREATE)
          set(CMAKE_THREAD_LIBS_INIT "-lpthread")
          set(CMAKE_HAVE_THREADS_LIBRARY 1)
          set(Threads_FOUND TRUE)
        endif()

        if(CMAKE_SYSTEM MATCHES "SunOS.*")
          # On sun also check for -lthread
          CHECK_LIBRARY_EXISTS(thread thr_create "" CMAKE_HAVE_THR_CREATE)
          if(CMAKE_HAVE_THR_CREATE)
            set(CMAKE_THREAD_LIBS_INIT "-lthread")
            set(CMAKE_HAVE_THREADS_LIBRARY 1)
            set(Threads_FOUND TRUE)
          endif()
        endif()
      endif()
    endif()

    if(NOT CMAKE_HAVE_THREADS_LIBRARY)
      # If we did not found -lpthread, -lpthread, or -lthread, look for -pthread
      if("THREADS_HAVE_PTHREAD_ARG" MATCHES "^THREADS_HAVE_PTHREAD_ARG")
        message(STATUS "Check if compiler accepts -pthread")
        try_run(THREADS_PTHREAD_ARG THREADS_HAVE_PTHREAD_ARG
          ${CMAKE_BINARY_DIR}
          ${CMAKE_ROOT}/Modules/CheckForPthreads.c
          CMAKE_FLAGS -DLINK_LIBRARIES:STRING=-pthread
          COMPILE_OUTPUT_VARIABLE OUTPUT)

        if(THREADS_HAVE_PTHREAD_ARG)
          if(THREADS_PTHREAD_ARG STREQUAL "2")
            set(Threads_FOUND TRUE)
            message(STATUS "Check if compiler accepts -pthread - yes")
          else()
            message(STATUS "Check if compiler accepts -pthread - no")
            file(APPEND
              ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
              "Determining if compiler accepts -pthread returned ${THREADS_PTHREAD_ARG} instead of 2. The compiler had the following output:\n${OUTPUT}\n\n")
          endif()
        else()
          message(STATUS "Check if compiler accepts -pthread - no")
          file(APPEND
            ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
            "Determining if compiler accepts -pthread failed with the following output:\n${OUTPUT}\n\n")
        endif()

      endif()

      if(THREADS_HAVE_PTHREAD_ARG)
        set(Threads_FOUND TRUE)
        set(CMAKE_THREAD_LIBS_INIT "-pthread")
      endif()

    endif()
  endif()
endif()

编辑3

使用最小的Cmakelists.txt如下:

cmake_minimum_required (VERSION 2.4)
find_package(Threads)

其中产生了以下输出:

-- Looking for include file pthread.h
-- Looking for include file pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found.
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE 

Answer 1

运行cmake时发生了问题。虽然，在这种情况下，cmake 不是问题，错误是无声的，与 -lpthreads 相关的错误/警告是唯一写入 cmake 错误日志文件的内容，尽管这并没有引起任何问题。我已经完成了 cmakelists.txt 的最小版本并开始逐行测试它，直到我发现哪个包导致它停止：最后我发现它是版本不匹配......

提示：搜索实际的错误信息

通常，您会查找最后一条错误消息。然而，这种（通常有用的）策略在这种情况下会误入歧途。

您正在查看的是CMakeCache.txt、CMakeOutput.log或CMakeError.log。怎么会？当配置阶段的某些宏或测试失败时，CMake 会“帮助”将这些文件转储到输出。不幸的是，这些文件可能有数千行长，并且通常包含许多 "*** Error: xyz"条目，用于各种配置检查。 " -lpthreads"的一个偶然碰巧是日志中的最后一个......

解决方案：从顶部查看日志，确定配置检查的部分，找到点之前的最后一次配置检查，CMake 识别失败并转储其日志。您也可以尝试搜索文本“ Configuring incomplete, errors occurred!”

通常，您会在那里找到非常精确的实际错误消息，或者至少您会找到最后调用的宏或函数的名称/路径，这使您可以查明实​​际出了什么问题。

Answer 2

在 Ubuntu 18.04.1 LTS 上，此安装为我提供了所需的所有文件：

apt -y install libboost-tools-dev libboost-thread1.62-dev magics++

/usr/lib/x86_64-linux-gnu/libpthread.a
/usr/lib/x86_64-linux-gnu/libpthread.so
/usr/lib/x86_64-linux-gnu/libpthread_nonshared.a

之后不再出现错误“/usr/bin/ld: 找不到 -lpthreads”