Cross-compile C++ for Windows from WSL2 using Clang/LLVM

A working example of a C++ project compiling for Windows from Ubuntu on WSL using Clang/LLVM.

Requirements

• Make
• Docker
• Windows 10
  • Build Tools for Visual Studio 2019
    • Install Desktop development with C++ (ID: Microsoft.VisualStudio.Workload.VCTools)
  • Windows Subsystem for Linux
    • Ubuntu on WSL
      • LLVM for Ubuntu
      • CMake for Ubuntu

Notes

• This example CMake C++ project is taken from Step 1 of the CMake Tutorial.

• The clang_windows_cross.cmake toolchain file was taken from a gist by HilmJulien, whom based it on WinMsvc.cmake toolchain file provided by LLVM.

• The version of your MSVC or Windows 10 SDK may differ depending on when you installed the Build Tools for Visual Studio 2019.

  To figure out what version you have installed check the following directories.

  $ make shell
  
  root@b69d7b2d42ef:/usr/bin# ls /opt/msvc/VC/Tools/MSVC
  14.29.30037
  
  root@b69d7b2d42ef:/usr/bin# ls /opt/msvc/Program\ Files/Windows\ Kits/10/Include
  10.0.19041.0

  Update the variables in clang_windows_cross.cmake appropriately.

Getting Started

1. Clone this repository (with submodules).

   git clone --recursive git@github.com:joshua-barnett/cross-compile-for-windows-from-wsl.git

2. Run make (has to be ran 3 times for CMake to pick up the dependencies).

   $ make
   docker build --tag windows-cpp-build-tools .
   [+] Building 0.1s (14/14) FINISHED                                                                                       
   => [internal] load build definition from Dockerfile                                                                0.0s
   => => transferring dockerfile: 38B                                                                                 0.0s
   => [internal] load .dockerignore                                                                                   0.0s
   => => transferring context: 2B                                                                                     0.0s
   => [internal] load metadata for docker.io/library/ubuntu:20.04@sha256:aba80b77e27148d99c034a987e7da3a287ed4553903  0.0s
   => https://raw.githubusercontent.com/mstorsjo/msvc-wine/84a46610378ef6118e60fc5d53a161f12e8d1b76/vsdownload.py     0.0s
   => [windows-cpp-build-tools 1/5] FROM docker.io/library/ubuntu:20.04@sha256:aba80b77e27148d99c034a987e7da3a287ed4  0.0s
   => CACHED [windows-cpp-build-tools 2/5] RUN apt-get update && apt-get install --yes --no-install-recommends pytho  0.0s
   => CACHED [windows-cpp-build-tools 3/5] WORKDIR /opt/msvc                                                          0.0s
   => CACHED [windows-cpp-build-tools 4/5] ADD https://raw.githubusercontent.com/mstorsjo/msvc-wine/84a46610378ef611  0.0s
   => CACHED [windows-cpp-build-tools 5/5] RUN PYTHONUNBUFFERED=1 python vsdownload.py --accept-license --only-unpac  0.0s
   => CACHED [cmake-llvm 2/5] COPY --from=windows-cpp-build-tools /opt/msvc /opt/msvc                                 0.0s
   => CACHED [cmake-llvm 3/5] RUN apt-get update && apt-get install --no-install-recommends --yes wget=1.20.3-1ubunt  0.0s
   => CACHED [cmake-llvm 4/5] RUN ln -s /usr/lib/llvm-12/bin/clang /usr/bin/clang-cl-12                               0.0s
   => CACHED [cmake-llvm 5/5] RUN mv /opt/msvc/Program Files/Windows Kits/10/Lib/10.0.19041.0/um/x64/kernel32.Lib /o  0.0s
   => exporting to image                                                                                              0.0s
   => => exporting layers                                                                                             0.0s
   => => writing image sha256:eeb938cf86b2cf7e80297eb42746f7672a0059996db9ff1f5b9733347f360a21                        0.0s
   => => naming to docker.io/library/windows-cpp-build-tools                                                          0.0s
   docker run --interactive --rm --tty --volume `pwd`:/usr/src --workdir /usr/src windows-cpp-build-tools make build
   mkdir -p Step1_build 
   wget -q -O - https://www.oxpal.com/downloads/uv-checker/checker-map_tho.png > Step1_build/hello_world.png
   cd Step1_build; cmake -Wno-dev -DCMAKE_MODULE_PATH=../cmake/sdl2 -DCMAKE_TOOLCHAIN_FILE=../clang_windows_cross.cmake ../Step1
   -- The C compiler identification is Clang 12.0.1 with MSVC-like command-line
   -- The CXX compiler identification is Clang 12.0.1 with MSVC-like command-line
   -- Detecting C compiler ABI info
   -- Detecting C compiler ABI info - done
   -- Check for working C compiler: /usr/bin/clang-cl-12 - skipped
   -- Detecting C compile features
   -- Detecting C compile features - done
   -- Detecting CXX compiler ABI info
   -- Detecting CXX compiler ABI info - done
   -- Check for working CXX compiler: /usr/bin/clang-cl-12 - skipped
   -- Detecting CXX compile features
   -- Detecting CXX compile features - done
   -- Found OpenGL: opengl32   
   -- Found SDL2: /usr/src/Step1_build/_deps/sdl2-src/lib/x64/SDL2.lib (found version "2.0.14") 
   -- Found SDL2main: /usr/src/Step1_build/_deps/sdl2-src/lib/x64/SDL2main.lib (found version "2.0.14") 
   -- Found SDL2_image: /usr/src/Step1_build/_deps/sdl2_image-src/lib/x64/SDL2_image.lib (found version "2.0.5") 
   -- Configuring done
   -- Generating done
   -- Build files have been written to: /usr/src/Step1_build
   cd Step1_build; cmake --build .
   make[1]: Entering directory '/usr/src/Step1_build'
   make[2]: Entering directory '/usr/src/Step1_build'
   make[3]: Entering directory '/usr/src/Step1_build'
   Scanning dependencies of target Tutorial
   make[3]: Leaving directory '/usr/src/Step1_build'
   make[3]: Entering directory '/usr/src/Step1_build'
   [ 50%] Building CXX object CMakeFiles/Tutorial.dir/tutorial.cxx.obj
   [100%] Linking CXX executable Tutorial.exe
   make[3]: Leaving directory '/usr/src/Step1_build'
   [100%] Built target Tutorial
   make[2]: Leaving directory '/usr/src/Step1_build'
   make[1]: Leaving directory '/usr/src/Step1_build'

3. Run the resulting Tutorial.exe executable in the Step1_build directory from Windows.