如何告诉 CMake 在 Windows 上使用 Clang?

问题描述

我有一个使用 CMake 构建的 C++ 项目.我通常在 OSX 上构建，但现在我也在尝试让 Windows 版本也能正常工作.出于兼容性原因，我想在 Windows 上使用 Clang.

I have a C++ project that builds using CMake. I usually build on OSX but now I am trying to get a Windows version working too. I would like to use Clang on Windows for compatibility reasons.

我从 LLVM 安装了预编译的 Clang 3.8 二进制文件:

I installed the pre-compiled Clang 3.8 binary from LLVM:

C:Program FilesLLVMinclang.exe
C:Program FilesLLVMinclang++.exe

它也安装在我的 PATH 上:

It is also installed on my PATH:

>clang++
clang++.exe: error: no input files

我有两个问题:

1. 当我调用 cmake --build 时，如何告诉 CMake 使用 clang++?
2. 如何在构建 CMake 配置的编译器之前检查?

1. How do I tell CMake to use clang++ when I call cmake --build?
2. How can I check before building which compiler CMake is configured with?

推荐答案

除了 Clang 编译器本身之外，您还需要一个适用于 Windows 的构建/链接环境.

You also need - in addition to the Clang compilers itself - an build/link environment for Windows.

最新的 CMake 3.6 版本确实在 Windows 上集成了多个受支持的 Clang 构建环境(例如 Visual Studio、Cygwin；请参阅 发行说明).

The latest CMake 3.6 builds do have several integrated supported Clang build environments on Windows (e.g. Visual Studio, Cygwin; see Release Notes).

我刚刚用

• LLVM-3.9.0-r273898-win32.exe 来自 http://llvm.org/builds/
• cmake-3.6.0-rc4-win64-x64.msi 来自 https://cmake.org/download/
• Microsoft VS2015 社区版 14.0.23107.0 版

全部安装到其标准路径，并在全局 PATH 环境中使用它们的 bin 目录.

All installed to their standard paths with their bin directories in the global PATH environment.

您需要知道的部分是使用 CMake -T"LLVM-vs2014" 命令行选项设置正确的工具集.在配置过程中，CMake 会告诉你它找到/采用了哪个编译器.

The part you need to know is setting the right toolset with the CMake -T"LLVM-vs2014" command line option. During the configuration process CMake will let you know which compiler it has found/taken.

CMakeLists.txt

cmake_minimum_required(VERSION 3.6)

project(HelloWorld)

file(
    WRITE main.cpp 
        "#include <iostream>
"
        "int main() { std::cout << "Hello World!" << std::endl; return 0; }"
)
add_executable(${PROJECT_NAME} main.cpp)

Windows 控制台

...> mkdir VS2015
...> cd VS2015
...VS2015> cmake -G"Visual Studio 14 2015" -T"LLVM-vs2014" ..
-- The C compiler identification is Clang 3.9.0
-- The CXX compiler identification is Clang 3.9.0
-- Check for working C compiler: C:/Program Files (x86)/LLVM/msbuild-bin/cl.exe
-- Check for working C compiler: C:/Program Files (x86)/LLVM/msbuild-bin/cl.exe -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files (x86)/LLVM/msbuild-bin/cl.exe
-- Check for working CXX compiler: C:/Program Files (x86)/LLVM/msbuild-bin/cl.exe -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: .../VS2015
...VS2015> cmake --build . 
Microsoft (R)-Buildmodul, Version 14.0.23107.0
[...]
...VS2015> DebugHelloWorld.exe
Hello World!

安装提示

请注意，我在设置过程中已将 LLVM 添加到我的搜索路径中:

Please note that I have added LLVM to my search paths during setup:

并且您可以在任何 VS 项目的属性页面中交叉检查可用的平台工具集":

And you can crosscheck the available "Platform Toolsets" in any VS project's property page:

参考资料

• 什么是-D定义告诉Cmake在哪里可以找到nmake?
• Clang 链接器?
• 使用 CMake 在 GCC 和 Clang/LLVM 之间切换

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