cpp-mod-mgr

A tool for using import std; with cross-platform C++ code

TODO: Document how this tool works (after I've published it...)

I've been trying out C++23 and modules (including import std;) across GCC, Clang (on Mac!), and MSVC. Currently, it appears to be working on MacOX with LLVM 22 (custom installed using HomeBrew), Linux (Debian) with a 'from source' build of GCC 16.1, and Windows 11 with Visual Studio 2026 compilers.

There's a single big mess that the import std; work leaves as an exersize for the user: How to manage the vendor-specific "Binary Module Interface" (BMI) files. So, since I got the basics working, I'm adding a per-user BMI cache so that, as long as you've got the correct compiler installed, you shouldn't have to do anything else. I'm going to put them in ${Platform Cache Location}/cpp.module.cache.

I have looked at the initial CMake support, but it's clearly experimental, and I really didn't like the idea of sticking some awful GUID in my build system to do this stuff. So I wrote a bunch of code, instead, because that's clearly the better way to go :/

Here are details:

| | | | ----- | ----------------------------------------------------------- | | MacOS | Using a custom Clang | | Linux | Using a custom GCC | | Win11 | Using import std |

Here's some documentation I've found useful to get this up and going:

• Modern C++ Modules Practice
• C++ Modules an CMake
• CMake C++ Module docs

Other notes:

• Putting #include's above imports, even in the 'global module fragent' section, seems like the right thing to get compilers to stop whining. I think this mostly eliminates the value of import std; but it does allow decent compatibility with non-module (read "all") external libraries.

What's in this repo

| Folder | Contents | | ------------------ | ------------------------------------------------------------------ | | src | The Typescript code for the module manager | | testing | CMake & C++ code | | docs | Documentation for the custom build stuff | | build | The bundled javascript code (exists after you run bun run build) | | node_modules | This is where javascript external dependencies get installed |