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https://github.com/jcf/home-manager-restart-emacs


https://github.com/jcf/home-manager-restart-emacs

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README 

        
#+title: Home Manager + restart-emacs

#+startup: content



Double-wrapping Emacs causes problems accessing packages, native compilation,

and restarting Emacs. This double-wrapping problem occurs when one uses the

=with*= functions more than once when producing an Emacs derivation.



Home Manager uses =emacsPackagesFor= and =emacsWithPackages= to build a final

package that shows up on one's machine, and when one uses those same mechanisms

to configure Emacs via Home Manager, double-wrapping will occur.



I am only using Home Manager's options to configure Emacs and running into

issues when restarting, where I see an invocation directory missing the

=with-packages= suffix.



* Contents                                                              :TOC:

- [[#restartemacs][=restart=emacs=]]

- [[#home-manager][Home Manager]]

- [[#emacs-wrapper][Emacs wrapper]]

- [[#nix-store][Nix store]]

  - [[#everything-emacs][Everything Emacs]]

- [[#references][References]]



* =restart=emacs=

Emacs has the ability the restart itself via =restart-emacs=.



#+begin_src emacs-lisp

(defun restart-emacs ()

  "Kill the current Emacs process and start a new one.

This goes through the same shutdown procedure as

`save-buffers-kill-emacs', but instead of killing Emacs and

exiting, it re-executes Emacs (using the same command line

arguments as the running Emacs)."

  (interactive)

  (save-buffers-kill-emacs nil t))

#+end_src



=save-buffers-kill-emacs= eventually calls =kill-emacs= with the =restart=

argument. The lengthy implementation of =kill-emacs=, implemented in C,

ultimately executes the original Emacs process by combining

=initial_emacs_executable=.



#+begin_src c

DEFUN ("kill-emacs", Fkill_emacs, Skill_emacs, 0, 2, "P",

       doc: /* Exit the Emacs job and kill it.

If ARG is an integer, return ARG as the exit program code.

If ARG is a string, stuff it as keyboard input.

Any other value of ARG, or ARG omitted, means return an

exit code that indicates successful program termination.



If RESTART is non-nil, instead of just exiting at the end, start a new

Emacs process, using the same command line arguments as the currently

running Emacs process.



This function is called upon receipt of the signals SIGTERM

or SIGHUP, and upon SIGINT in batch mode.



The value of `kill-emacs-hook', if not void, is a list of functions

(of no args), all of which are called before Emacs is actually

killed.  */

       attributes: noreturn)

  (Lisp_Object arg, Lisp_Object restart)

{

  int exit_code;



#ifndef WINDOWSNT

  /* Do some checking before shutting down Emacs, because errors

     can't be meaningfully reported afterwards.  */

  if (!NILP (restart))

    {

      /* This is very unlikely, but it's possible to execute a binary

	 (on some systems) with no argv.  */

      if (initial_argc < 1)

	error ("No command line arguments known; unable to re-execute Emacs");



      /* Check that the binary hasn't gone away.  */

      if (!initial_emacs_executable)

	error ("Unknown Emacs executable");



      if (!file_access_p (initial_emacs_executable, F_OK))

	error ("Emacs executable \"%s\" can't be found", initial_argv[0]);

    }

#endif



#ifdef HAVE_LIBSYSTEMD

  /* Notify systemd we are shutting down, but only if we have notified

     it about startup.  */

  if (daemon_type == -1)

    sd_notify(0, "STOPPING=1");

#endif /* HAVE_LIBSYSTEMD */



  /* Fsignal calls emacs_abort () if it sees that waiting_for_input is

     set.  */

  waiting_for_input = 0;

  if (!NILP (find_symbol_value (Qkill_emacs_hook)))

    {

      if (noninteractive)

	safe_run_hooks (Qkill_emacs_hook);

      else

	call1 (Qrun_hook_query_error_with_timeout, Qkill_emacs_hook);

    }



#ifdef HAVE_X_WINDOWS

  /* Transfer any clipboards we own to the clipboard manager.  */

  x_clipboard_manager_save_all ();

#endif



  shut_down_emacs (0, (STRINGP (arg) && !feof (stdin)) ? arg : Qnil);



#ifdef HAVE_NS

  ns_release_autorelease_pool (ns_pool);

#endif



  /* If we have an auto-save list file,

     kill it because we are exiting Emacs deliberately (not crashing).

     Do it after shut_down_emacs, which does an auto-save.  */

  if (STRINGP (Vauto_save_list_file_name))

    {

      Lisp_Object listfile;

      listfile = Fexpand_file_name (Vauto_save_list_file_name, Qnil);

      unlink (SSDATA (listfile));

    }



#ifdef HAVE_NATIVE_COMP

  eln_load_path_final_clean_up ();

#endif



  if (!NILP (restart))

    {

      turn_on_atimers (false);

#ifdef WINDOWSNT

      if (w32_reexec_emacs (initial_cmdline, initial_wd) < 0)

#else

      initial_argv[0] = initial_emacs_executable;

      if (execvp (*initial_argv, initial_argv) < 1)

#endif

	emacs_perror ("Unable to re-execute Emacs");

    }



  if (FIXNUMP (arg))

    exit_code = (XFIXNUM (arg) < 0

		 ? XFIXNUM (arg) | INT_MIN

		 : XFIXNUM (arg) & INT_MAX);

  else

    exit_code = EXIT_SUCCESS;

  exit (exit_code);

}

#+end_src



* Home Manager

When one manages one's Emacs with Home Manager and Nix, it's necessary to wrap

Emacs to install packages like =vterm= where compiling external dependencies

causes issues.



A minimal Emacs configuration with Home Manager might look like this:



#+begin_src nix

programs.emacs = {

  enable = true;



  package = pkgs.emacs-unstable-pgtk;



  extraPackages = epkgs: [epkgs.vterm];



  overrides = final: prev: {

    # `emacs-28` patches are compatible with `emacs-29`.

    #

    # Where a compatible path exists, there is a symlink upstream to keep

    # things clean, but GitHub doesn't follow symlinks to generate the

    # responses we need (instead GitHub returns the target of the symlink).

    patches =

      (prev.patches or [])

      ++ [

        # Fix OS window role (needed for window managers like yabai)

        (pkgs.fetchpatch {

          url = "https://raw.githubusercontent.com/d12frosted/homebrew-emacs-plus/master/patches/emacs-28/fix-window-role.patch";

          sha256 = "0c41rgpi19vr9ai740g09lka3nkjk48ppqyqdnncjrkfgvm2710z";

        })

        # Use poll instead of select to get file descriptors

        (pkgs.fetchpatch {

          url = "https://raw.githubusercontent.com/d12frosted/homebrew-emacs-plus/master/patches/emacs-29/poll.patch";

          sha256 = "0j26n6yma4n5wh4klikza6bjnzrmz6zihgcsdx36pn3vbfnaqbh5";

        })

        # Enable rounded window with no decoration

        (pkgs.fetchpatch {

          url = "https://raw.githubusercontent.com/d12frosted/homebrew-emacs-plus/master/patches/emacs-29/round-undecorated-frame.patch";

          sha256 = "0x187xvjakm2730d1wcqbz2sny07238mabh5d97fah4qal7zhlbl";

        })

        # Make Emacs aware of OS-level light/dark mode

        (pkgs.fetchpatch {

          url = "https://raw.githubusercontent.com/d12frosted/homebrew-emacs-plus/master/patches/emacs-28/system-appearance.patch";

          sha256 = "14ndp2fqqc95s70fwhpxq58y8qqj4gzvvffp77snm2xk76c1bvnn";

        })

      ];

  };

};

#+end_src



With this configuration, one can get their hands on the generated Emacs package

(say for setting up aliases or automating addition to one's Dock on macOS) using

Home Manager's configuration.



#+begin_src nix

config.home-manager.users.${username}.programs.emacs.finalPackage;

#+end_src



In my case, that looks something like this:



#+begin_example

$ nix repl --extra-experimental-features 'flakes repl-flake' .

nix-repl> darwinConfigurations.max.config.home-manager.users.jcf.programs.emacs.finalPackage.outPath

#+end_example



At the time of writing, my =outPath= is:



#+name: emacs

#+begin_example

/nix/store/q9aj7679vid9l5hxlr5dm1bssgskrgxh-emacs-unstable-with-packages-29.2

#+end_example



* Emacs wrapper

The package we've installed comes with a wrapper script that starts Emacs with

things like packages and user configuration available.



Looking at the generated wrapper script, the final =exec= uses an Emacs package

without the =-with-packages= suffix.



#+begin_src sh :var emacs=emacs :results output verbatim :wrap src sh :exports both

tail -1 "$(tr -d "\n" <<< $emacs)/Applications/Emacs.app/Contents/MacOS/.Emacs-wrapped"

#+end_src



#+results:

#+begin_src sh

exec /nix/store/wmpm0b7avcdspqw4dhhb05dign2mwp4s-emacs-unstable-29.2/Applications/Emacs.app/Contents/MacOS/Emacs "$@"

#+end_src



The problem seems to be that this wrapper script launches a version of Emacs

without the =-with-packages= suffix in the name.



Emacs derivation out path:



#+begin_example

/nix/store/q9aj7679vid9l5hxlr5dm1bssgskrgxh-emacs-unstable-with-packages-29.2

#+end_example



In the wrapper script, we execute a different Emacs derivation:



#+begin_example

/nix/store/wmpm0b7avcdspqw4dhhb05dign2mwp4s-emacs-unstable-29.2

#+end_example



* Nix store

** Everything Emacs

#+begin_src sh :results output list :exports both

fd --type directory --max-depth 1 'emacs-' /nix/store

#+end_src



#+results:

#+begin_example

- /nix/store/awnky7y0plbwqaq8hnmh8gcypzdwypzj-emacs-unstable-with-packages-29.2/

- /nix/store/25a8ihlnwdalc7sr35mlzbrr4bgfbkna-emacs-28.2/

- /nix/store/qjgpw70kwz140wrj7lk2pils9mnnfcac-emacs-vterm-20230417.424/

- /nix/store/zjv8h8hiixkxvz60xsmr6ds1q2rih2b6-emacs-packages-deps/

- /nix/store/xclpf9yyqzjfdwjbay17q85adiqmdwgj-emacs-vterm-20230417.424/

- /nix/store/vs9w294n6gm0mqdy3l59qjhw0k2b42ks-emacs-unstable-29.2/

- /nix/store/vlw849n0qpagqh0126d9mkyjz2l05mvw-emacs-packages-deps/

- /nix/store/xj5b3ng8dwbfcp6dv4lnnqi1c7k4qavx-emacs-unstable-with-packages-29.1.90/

- /nix/store/h9b1yj25ipw8wm8anm7fbi8rqc1w7vn9-emacs-unstable-29.1.90/

- /nix/store/q9aj7679vid9l5hxlr5dm1bssgskrgxh-emacs-unstable-with-packages-29.2/

- /nix/store/qhh1aa95id3jzqvxj169v61l4l7ycq72-emacs-unstable-29.2/

- /nix/store/4iraqrh9ylgkasclhf1bdn6g1ax8yai5-emacs-vterm-20230417.424/

- /nix/store/sfcz6812wwfl9l0060gf1l48176j1x75-emacs-vterm-20230417.424/

- /nix/store/18xc5gqydknqwl6fz89c0dnvcf24d3wa-emacs-unstable-with-packages-29.1.90/

- /nix/store/5f66cav1zv6xcdv8bblydm6az4whgfcx-emacs-packages-deps/

- /nix/store/6g5hxdxllqv3xy6ih530hgh04yf8wmlp-emacs-packages-deps/

- /nix/store/nax7zyq8hznfc8x66kamybrmidacvmk9-emacs-packages-deps/

- /nix/store/vi4cr17hfz9l5b8x0k6qa521k33pn80r-emacs-unstable-with-packages-29.2/

- /nix/store/wmpm0b7avcdspqw4dhhb05dign2mwp4s-emacs-unstable-29.2/

- /nix/store/qijacydwqch29a3vzkcxmbcnqsak7j7c-emacs-packages-deps/

- /nix/store/4d324ihqqh0yh54wszs7j0g2cjb5j8id-emacs-pgtk-29.1/

- /nix/store/hjqjdcdwymvwl65x58y87zq7mdldinpr-emacs-unstable-with-packages-29.2/

- /nix/store/plxbh95byi46aly8gsjk2yrnykx5whxj-emacs-vterm-20230417.424/

- /nix/store/n36m91f7mg2sb6ja93impyvlcxxk7zw7-emacs-packages-deps/

- /nix/store/zw9j2zm4gbbqynwasaaf2vc8jvzl0rp8-emacs-unstable-29.1.90/

- /nix/store/cxd0vqwxjkrr5d1s2s72kygkxkjh3pcn-emacs-vterm-20230417.424/

- /nix/store/50ngyajnf7zk6cj9b4r7648dhy1kdvvq-emacs-unstable-with-packages-with-packages-29.2/

- /nix/store/l80jsxbmgvqvjzbg656mxvzj8lp3vla2-emacs-pgtk-with-packages-29.1/

- /nix/store/r30zr2df02is7qk4g7lnzlsmfkzwsbpj-emacs-unstable-with-packages-29.2/

#+end_example



* References

- https://github.com/NixOS/nixpkgs/issues/145302

- https://github.com/NixOS/nixpkgs/issues/267548#issuecomment-1833505396

- https://github.com/nix-community/emacs-overlay/issues/386

- https://github.com/nix-community/emacs-overlay/issues/388#issuecomment-1933320497

- https://github.com/progfolio/elpaca/issues/251#issuecomment-1933386074