如何让CMake在Ubuntu上识别pthread？ [英] How to get CMake to recognize pthread on Ubuntu?

问题描述

如果我直接在命令行上编译g ++，我可以看到我需要的一切是：

If I compile on the command-line with g++ directly, I can see everything I need is there:

$ g++ -pthread test.cpp
$ ldd a.out
    linux-vdso.so.1 =>  (0x00007fffd05b3000)
    libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f4a1ba8d000)
    libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f4a1b870000)
    ...more...

然后我尝试为这个5行测试应用程序创建一个简单的cmake文件：

Then I try to create a simple cmake file for this 5-line test app:

$ cat CMakeLists.txt 
PROJECT ( Test CXX )
CMAKE_MINIMUM_REQUIRED ( VERSION 2.8 )
FIND_PACKAGE ( Threads REQUIRED )
ADD_EXECUTABLE ( test test.cpp )
TARGET_LINK_LIBRARIES ( test ${CMAKE_THREAD_LIBS_INIT} )

但是，我不知道为什么CMake找不到需要使用主题：

However, I cannot figure out why CMake doesn't find what it needs to use for Threads:

$ cd build/
$ cmake ..
CMake Error at /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:97 (MESSAGE):
  Could NOT find Threads (missing: Threads_FOUND)
Call Stack (most recent call first):
  /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:288 (_FPHSA_FAILURE_MESSAGE)
  /usr/share/cmake-2.8/Modules/FindThreads.cmake:166 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  CMakeLists.txt:4 (FIND_PACKAGE)
-- Configuring incomplete, errors occurred!

推荐答案

我可能失去了2个小时。这里是解决方案：

Oh, this was was a pain! I probably lost 2 hours on this. Here is the solution:

CMake使用短'C'应用程序测试/尝试的东西。如果CMakeLists.txt声明C ++用于项目，没有也列出C，那么这些短路测试中的一些错误地失败，并且cmake然后认为那些东西没有找到。

CMake uses short 'C' applications to test/try things. If the CMakeLists.txt states that C++ is used for the project, without also listing C, then some of those shorts tests incorrectly fail, and cmake then thinks those things aren't found.

解决方案是从这里改变CMakeLists的第一行：

The solution was to change the first line of CMakeLists from this:

PROJECT ( Test CXX )

...以包含C作为语言：

...to include C as a language:

PROJECT ( Test C CXX )

c> build ，重新创建它，然后一切工作：

Then delete build, recreate it, and everything then works:

rm -rf build
mkdir build
cd build
cmake ..

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