Overview

emacs-module-rs provides high-level Rust binding and tools to write Emacs’s dynamic modules. It is easy to use if you know either Rust or Emacs.

It currently supports:

• Stable Rust (latest stable recommended; 1.87 minimum).
• Emacs 25 or above, built with module support.
• Linux, macOS, FreeBSD, Windows.

Setting up

• Make sure your Emacs was compiled with module support. Check that module-file-suffix is not nil, and the function module-load is defined.
  • On macOS, the recommended installation method is MacPorts (emacs-app and emacs-mac-app).
  • On Windows, use either an official GNU build, or MSYS2’s package: pacman -S mingw-w64-ucrt-x86_64-emacs.
• Install the Rust toolchain with rustup.
  • On Windows, use the stable-gnu toolchain. Build in the MSYS2 shell that matches the C runtime (CRT) of your Emacs:
    • MINGW64 (mingw-w64-x86_64-toolchain) for official GNU builds, which use MSVCRT.
    • UCRT64 (mingw-w64-ucrt-x86_64-toolchain) for official -UCRT64 builds (Emacs 31+) and MSYS2’s package, which use UCRT.

Notes

• When the optional feature bindgen is enabled, the raw binding will be generated from emacs-module.h at build time. You will also need to install clang. (This is recommended only for troubleshooting.) For example, on Windows:

  # In Powershell
  scoop install llvm
  
  $env:LIBCLANG_PATH = "$(scoop prefix llvm)\bin"
  cargo build --all
  

Known Issues

There is a bug (see issue #1) with Emacs 26 on Linux that prevents it from loading any dynamic modules (even those written in C), if:

• Emacs is built without thread support.
• The OS is Ubuntu 16.04 (Xenial).