C++ cmake返回错误为；未定义对pthread“u create”的引用；

我正在尝试构建webrtc项目：

当我运行

cmake.

时，出现以下错误：

WEBRTCBUILD = Release
WEBRTCROOT = /home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer/../webrtc
WEBRTCDESKTOPCAPTURE= ON
CMAKE_CXX_COMPILER_ID=GNU
ALSA_FOUND = FALSE
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
WEBRTC_LIBRARY
    linked by target "webrtc-streamer" in directory /home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer

-- Configuring incomplete, errors occurred!
See also "/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer/CMakeFiles/CMakeOutput.log".
See also "/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer/CMakeFiles/CMakeError.log".

以及此后的内容“CMakeError.log”

确定pthread_create exist是否失败，输出如下：
更改目录：/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc streamer/CMakeFiles/CMakeTmp
运行构建命令：“/usr/bin/make”“cmTC_13271/fast”
/usr/bin/make-f CMakeFiles/cmTC_13271.dir/build.make CMakeFiles/cmTC_13271.dir/build
make[1]：输入目录“/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc streamer/CMakeFiles/CMakeTmp”
构建C对象cmakfiles/cmTC_13271.dir/CheckSymbolExists.C.o
/usr/bin/cc-fPIE-o CMakeFiles/cmtc13271.dir/CheckSymbolExists.c.o-c/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc streamer/CMakeFiles/CMakeTmp/CheckSymbolExists.c
链接C可执行文件cmTC_13271
/usr/bin/cmake-E cmake_link_脚本CMakeFiles/cmTC_13271.dir/link.txt--verbose=1
/usr/bin/cc cmakfiles/cmTC_13271.dir/CheckSymbolExists.c.o-o cmTC_13271-rdynamic
cmakfiles/cmTC_13271.dir/CheckSymbolExists.c.o:在函数“main”中：
CheckSymbolExists.c:（.text+0x1b）：未定义对“pthread_create”的引用
collect2:错误：ld返回了1个退出状态
CMakeFiles/cmTC_13271.dir/build.make:97:目标“cmTC_13271”的配方失败
make[1]：***[cmTC_13271]错误1
make[1]：离开目录“/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc streamer/CMakeFiles/CMakeTmp”
Makefile:126:目标“cmTC_13271/fast”的配方失败
make:**[cmTC_13271/fast]错误2
文件/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc streamer/CMakeFiles/CMakeTmp/CheckSymbolExists.c：
/* */
#包括
int main（int argc，字符**argv）
{
（无效）argv；
#ifndef pthread_创建
返回（（int*）（&pthread_create））[argc]；
#否则
（无效）argc；
返回0；
#恩迪夫
}

在CMakeLists.txt之后：

pthread库安装在我的ubuntu PC上，因为用-lpthread编译测试文件“test.c”不会出现问题

---

我缺少什么？

您需要将“pthread”添加到CMakeLists.txt中的“target\u link\u libraries”部分

[编辑]

正如@arrowd所建议的，正确的方法是使用“FindThreads”：

---

这是否回答了您的问题？从建议的副本中，特别是这个答案可能是相关的：@MarekR这不是关于将问题链接到pthread。这个问题是关于cmake的问题。我可以编译带有-lpthread的测试文件（.c），而不需要任何problem@MOHAMED您的错误是链接问题。第二条注释直接指向如何在cmake项目中修复它的答案（我提供了两份）。错误是没有找到

webrtc

library，它应该是

webrtc\u library

变量的值。

CMakeError.log

的内容与问题完全无关，您可以安全地将其从帖子中删除。具体来说，该行失败：。如中所述，WebRTC SDK应位于

。/WebRTC

目录下。一般来说，请确保您拥有它。正确的方法是使用

FindThreads

模块及其定义的变量。好的，谢谢您提供的信息，我不知怎么错过了。

Determining if the pthread_create exist failed with the following output:
Change Dir: /home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_13271/fast"
/usr/bin/make -f CMakeFiles/cmTC_13271.dir/build.make CMakeFiles/cmTC_13271.dir/build
make[1]: Entering directory '/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_13271.dir/CheckSymbolExists.c.o
/usr/bin/cc    -fPIE   -o CMakeFiles/cmTC_13271.dir/CheckSymbolExists.c.o   -c /home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_13271
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_13271.dir/link.txt --verbose=1
/usr/bin/cc       CMakeFiles/cmTC_13271.dir/CheckSymbolExists.c.o  -o cmTC_13271 -rdynamic 
CMakeFiles/cmTC_13271.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text+0x1b): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_13271.dir/build.make:97: recipe for target 'cmTC_13271' failed
make[1]: *** [cmTC_13271] Error 1
make[1]: Leaving directory '/home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_13271/fast' failed
make: *** [cmTC_13271/fast] Error 2

   
File /home/mohamed/Desktop/upwork/SoftwareExperts/test3/webrtc-streamer/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef pthread_create
  return ((int*)(&pthread_create))[argc];
#else
  (void)argc;
  return 0;
#endif
}