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Last active Sep 26, 2020
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Installing gccEmacs (native-comp) with Nix

Nix

Adding the overlay and configuring cachix

Option 1: Adding the overlay to configuration.nix or home.nix

Add the nix-community overlay to your nixpkgs. You can add the following to your configuration.nix (NixOS, non-user specific) or to your home-manager's home.nix. Note in the case of the latter, this will not be available for installation via nix-env.

{
  nixpkgs.overlays = [
    (import (builtins.fetchTarball {
      url = https://github.com/nix-community/emacs-overlay/archive/master.tar.gz;
    }))
  ];
}

See nixos or home-manager options for more information on adding overlays.

Option 2: Add to the overlays directory

echo "import (builtins.fetchTarball {
      url = https://github.com/nix-community/emacs-overlay/archive/master.tar.gz;
    })" >> $HOME/.config/nixpkgs/overlays/emacs.nix

Optional: Add cachix support to avoid compilation

As this package is installed via an overlay, it is not built by the Hydra CI/CD pipeline that underlies nixpkgs. Instead, the binary is built by the nix-community hydra and pushed to Cachix. Follow the instructions here to add the nix-community cachix.

nix-env -iA cachix -f https://cachix.org/api/v1/install
cachix use nix-community

You will need to ensure that you are are installing the emacs overlay from the nixos-unstable unstable channel, not the nixpkgs-unstable channel. If you are using home-manager, you will need to set your default channel to nixos-unstable (you can do this on non-NixOS systems, the difference is that nixos-unstable lags behind nixpkgs-unstable due to requiring more comprehensive tests before deployment). Alternatively, you can separately import nixos-unstable import <nixos-unstable> { overlays = [ overlay1 overlay2 ]; } separately, and use a separate channel specifically for emacs.

Installing emacs

If you followed option 2, the following will work.

nix-env -iA nixpkgs.emacsGcc

More likely, you will want to declaratively install in your configuration.nix or home.nix.

Home-manager provides a handy module, you can also add extra packages such as vterm.

{
  programs.emacs = {
    enable = true;
    package = pkgs.emacsGcc;
    extraPackages = (epkgs: [ epkgs.vterm ] );
  };
}

Alternatively you can add something like the following to you configuration.nix system packages

{
emacsWithPackages = (pkgs.emacsPackagesGen pkgs.emacsGcc).emacsWithPackages (epkgs: ([epkgs.vterm]));
}

Notes

As of 2020-08-03 the above works on fedora/ubuntu/debian and under NixOS. If you get an immediate segfault upon starting emacs, please ensure that your font is appropriately configured.

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