Cross-platform C++ playground

Introduction

This repo is for experimenting with building cross-platform C++ in Visual Studio (with an emphasis on module-based code) across Windows and Linux and across the big three C++ compilers: MSVC, GCC and Clang. It also functions as a useful testing ground for evaluating support of various different C++ features across the big three compilers. This repo was originally borne out of some experiments I did in my cpp-playground repo, before I realised this isn't just any other random experiment, but something worthwhile pursuing in a separate repo.

I intend to add CMake into the mix at some point, just to make things even more complicated.

Cross-compiling and building C++ with Visual Studio

Set up

This repo assumes you work on a Windows machine with WSL2 and that Visual Studio 2022 is your primary IDE. You'll need the Desktop development with C++ and the Linux and embedded development with C++ workloads. Building for Clang requires the C++ Clang Compiler for Windows and MSBuild Support for LLVM (clang-cl) toolset optional components.

Building for Clang

Visual Studio's Clang support requires installing the Clang components -- follow this for more info.

Building for Linux

• You need a WSL2 distro running on your machine. I use Ubuntu. You can list your WSL2 instances with wsl --list -v.
• Install the required tools for Visual Studio on your WSL2 VM: sudo apt install -y openssh-server build-essential gdb rsync make zip
• Enable SSH on the VM. Test locally with ssh -p 22 <username>@localhost.
• Configure Visual Studio to connect to the VM: TOOLS > Options > Cross Platform > Connection Manager.
• Install additional GCC/g++ versions if necessary (I use GCC-13/g++-13). Update the C++ Compiler option to point to the preferred compiler (and don't forget to change the language standard and enable additional flags like -fmodules-ts as appropriate for your compiler).
• You should be able to open the solution and build any one of the projects. If building for Linux, your WSL2 distro needs to be running (you can log into it with wsl ~ assuming you've set it as your default).

Notes

GCC's and Clang's support for C++20 modules is still a bit flaky and lags behind MSVC's support. In GCC-13, #including <chrono> appears to cause an ICE and GCC also appears to dislike it when a module implementation unit (e.g. somemodule.cpp) has the same name as its module interface unit (e.g. somemodule.ixx). I wasn't able to get modules behaving in Visual Studio with Clang, but I could build them by dropping to the x64 Native Tools Command Prompt for VS 2022 tool and following Rainer Grimm's instructions (linked below). One thing to note with Clang's implementation is the .cppm extension that gets compiled into a .pcm file.

Additional resources

• C++20: Module Support of the Big Three
• C++20: More Details about Module Support of the Big Three
• Clang/LLVM support in Visual Studio projects
• Walkthrough: Build and debug C++ with WSL 2 and Visual Studio 2022
• Tutorial: Create C++ cross-platform projects in Visual Studio
• C++ Compiler Support: useful to ensure features used in your cross-platform code align with your available compilers.
• C++ Standards Support in GCC
• C++ Support in Clang
• Microsoft C/C++ language conformance by Visual Studio version
• CMake's cxxmodules