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Build Custom Emacs from Git from Emacs
;;; build-emacs.el --- Build custom Emacs from sources -*- lexical-binding: t; -*-
;; Copyright (C) 2022 Arthur Miller
;; Author: Arthur Miller <>
;; Keywords: tools
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <>.
;;; Commentary:
;; Backup of my personal script to (re)build Emacs from within Emacs.
;; It will automatically pull emacs sources from git, apply custom patches,
;; and install a symlink to newly build Emacs in ~/.config/.
;; This is very opinionated and personal setup, don't use for anything but
;; inspriation :) or use on your own risk.
;; Run from the source directory; don't install Emacs. Add symlink/src and
;; symlink/lib-src to the PATH (for emacs and emacs-client executable). Symlink
;; is installed by the script in ~/.config/ directory (no sudo pass required).
;; It will create a worktree for a new build for the purpose of keeping the git
;; repository clean of any accidental changes so we can "git pull" without
;; git asking for eventual intervention in case of unstashed changes etc.
;; The old build is not removed automatically; for the reason of not being left
;; with buggy setup in case of breaking changes and alike. Symlink will
;; be changed, because in most of cases, new Emacs works, but just in case;
;; symlink is easy to revert to previous build. Harddrive space is cheap; I
;; typically execute emacs-clean-auto-worktrees after I have built Emacs several
;; times.
;; Worktrees also let us have several branches checked out at the same time, and
;; I do have some custom patches I use in my build. Those are placed in
;; "patches" directory and applied automatically at build time. Custom patched
;; worktrees are not removed by emacs-clean-auto-worktrees.
;; Typically use emacs-build-async. For debugging purposes use
;; emacs-build. Modify configuration to suit your needs. There are also some
;; hardcoded make option, modifty for your needs if used.
;; This is work in progress, done by me from time to time, when I get annoyed by
;; having to repeat som actions on each time I compile Emacs. This is not
;; actively developed!
;; Shell script should be able to bootstrap too, without need to have working
;; Emacs, and certainly less verbose then an elisp program, but stepping through
;; the code is indispensible when debugging. If someone finds this interesting
;; and translates to a shell script, please let me know.
;;; Code:
(defvar emacs-cflags-dbg "-gddb3 -O0 -march=native")
(defvar emacs-cflags-opt "-O2 -march=native")
(defvar emacs-configs
'(("default-with-native" "--with-native-compilation")
(defvar build-log "*build-log*")
(defun build-log ()
(and (get-buffer build-log)
(kill-buffer build-log))
(generate-new-buffer "*build-log*")
(with-current-buffer build-log
(read-only-mode -1)
(defun git (&rest args)
(apply #'call-process "git" nil build-log nil args))
(defun emq (&rest args)
(apply #'call-process "emacs" nil build-log nil "-Q" args))
(defun make (&rest args)
(apply #'call-process "make" nil build-log nil args))
(defun lns (&rest args)
(apply #'call-process "ln" nil build-log nil "-s" args))
(defun autogen (&rest args)
(apply #'call-process (expand-file-name "./") nil build-log nil args))
(defun configure (&rest args)
(apply #'call-process (expand-file-name "./configure") nil build-log nil args))
(defun git-root (&optional directory)
"Find git root in a git project.
If DIRECTORY is not given, return git root of DEFAULT-DIRECTORY.
This should correctly find git root even for worktrees placed outside of a git
repository as well as in subdirectories in main git repository."
(let* ((directory (expand-file-name (or directory default-directory)))
(git-dir (locate-dominating-file directory ".git"))
(git-file (and git-dir (expand-file-name ".git" git-dir))))
(if (and git-file (file-directory-p git-file))
(and git-file
(insert-file-contents-literally git-file)
(when (search-forward "gitdir: " nil t)
(let ((beg (point))
(end (search-forward ".git" nil t)))
(buffer-substring-no-properties beg (- end 4)))))))))
(defun autobuildp (name)
(catch 'auto
(dolist (build emacs-configs)
(if (string-match-p (car build) name)
(throw 'auto t)))))
(defun dirp (string) (= ?/ (aref string 0)))
(defun emacs-clean-auto-worktrees ()
"Remove auto-generated worktrees from configs. This will remove ALL but
the current one."
(let ((git-root (git-root source-directory))
(currtree (file-truename (expand-file-name "~/.config/emacs/"))))
(when git-root
(cd git-root)
(let ((out
(shell-command-to-string "git worktree list"))))))
(dolist (tree out)
(unless (string-match-p tree currtree)
(let ((worktree (expand-file-name
(concat "../" (file-name-nondirectory tree)))))
(message "Removing: %s" worktree)
;; these builds are not used for patching; all changes are misstakes
(git "worktree" "remove" "--force" worktree))))))))
(defun emacs-download-and-build (configname)
(let* ((config (assoc configname emacs-configs))
(build-name (car config))
(config (cdr config))
(git-root (git-root source-directory))
(format "../%s-%s" build-name (format-time-string "%y%m%d-%H%M%S")))
(status "Emacs build failed.")
(build-log (build-log)))
(cd git-root)
(git "pull")
(git "worktree" "add" worktree)
(when (file-directory-p worktree)
(let* ((worktree (concat worktree "/"))
(link (expand-file-name "~/.config/emacs"))
(target (expand-file-name "src/emacs" worktree)))
(cd worktree)
(let ((patches (directory-files "../patches/" t "patch" t)))
(dolist (patch patches) (git "apply" patch)))
(apply #'configure config)
(make "bootstrap" "-j8")
(make "-j8")
(when (file-executable-p target)
(if (file-exists-p link) (delete-file link))
(lns (expand-file-name worktree) link))))
(with-current-buffer build-log
(goto-char (point-max))
(insert status)
(write-file (concat (file-name-nondirectory worktree) ".log")))))
(defun emacs-patch (&optional patch-name)
"Add new Emacs patch."
(interactive "sPatch name: ")
(message "Patch name %s" patch-name)
(let ((pwd default-directory)
(worktree (format "../%s" patch-name))
(path (expand-file-name patch-name))
(git-root (git-root source-directory)))
(when (file-exists-p path)
(error "A worktree with this name already exists"))
(cd git-root)
(git "worktree" "add" worktree)
(cd worktree)
(message "Succesfully changed to %s directory." worktree)))
(defun emacs-remove-patch (&optional patch-name)
"Remove an Emacs patch."
(interactive "sPatch name: ")
(message "Patch name %s" patch-name)
(let ((pwd default-directory)
(wname (format "../%s" patch-name))
(wdir (expand-file-name (format "../%s/" patch-name)))
(path (expand-file-name patch-name))
(git-root (git-root source-directory)))
(unless (file-exists-p wname)
(error "A worktree with this name does not exist"))
(cd git-root)
(git "worktree" "remove" "--force" wname)
(if (equal pwd wdir) (cd "..") (cd pwd))
(message "%s removed." patch-name)))
(defun emacs-build ()
(completing-read "Configuration: " emacs-configs)))
(defun emacs-build-async ()
(setenv "CFLAGS" emacs-cflags-opt)
(let* ((config (completing-read "Configuration: " emacs-configs))
(concat "emacs -Q --batch -l "
"~/repos/emsrc/build-emacs.el "
"--eval '(emacs-download-and-build \"" config "\")'")))
(generate-new-buffer "*build-errors*")
(generate-new-buffer "*build-emacs*"))))
(provide 'build-emacs)
;;; build-emacs.el ends here
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