feat(cli): introduce DOOMPROFILELOAD{FILE,PATH} envvars

- Adds $DOOMPROFILELOADFILE: Controls where to read and write the
  profile loader. Changing this may be helpful for users on nix/guix,
  who have deployed Doom to a read-only location. This sets
  `doom-profile-load-file`.
- Changed profile load file's default location (used to be
  $EMACSDIR/profiles/init.el, is now $EMACSDIR/profiles/load.el). The
  gitignore was updated to reflect this.
- Adds $DOOMPROFILELOADPATH: A colon-delimited list of profile config
  files and directories (semi-colon on Windows) which dictate what Doom
  reads in order to discover your profiles. Config files are required to
  have an *.el extension. This sets `doom-profile-load-path`.
- Changes the nomenclature around this loader script. I used to refer to
  it as the profile bootstrapper. I'll now refer to it as the profile
  load file, and I've renamed `doom-profiles-bootstrap-file` to
  `doom-profile-load-file` to reflect this.
- The variables `doom-profile-dirs` and `doom-profile-config-files` were
  merged into doom-profile-load-path.
- Both envvars have also been documented in `doom help` (and
  $DOOMPROFILE's has been updated).

Ref: #6794

.gitignore

@@ -1,5 +1,5 @@
 # machine generated doom profiles or metadata
-/profiles/init.*el
+/profiles/*.el
 /.local*/
 
 # possible user config files

bin/doom

@@ -139,11 +139,24 @@ ENVIRONMENT VARIABLES:
     option also sets this variable.
 
   `$DOOMPROFILE'
-    (Not implemented yet) Which Doom profile to activate (default: \"current\").
+    Which Doom profile to activate (default: \"_@0\"). The `--profile' option
+    also sets this variable.
 
-  `$DOOMPROFILESDIR'
-    (Not implemented yet) Where to find or write generated Doom profiles
-    (default: `$EMACSDIR'/profiles).
+  `$DOOMPROFILELOADFILE'
+    Doom generates a profile loader script on 'doom sync' or 'doom profiles
+    sync'. By default, this file is written to and loaded from
+    $EMACSDIR/profiles/load.el. Set this envvar to change that. Note that this
+    envvar must be in scope for both interactive and non-interactive sessions
+    for it to be effective. This is especially useful for folks on Nix/Guix, who
+    have deployed Doom to a read-only directory.
+
+    Note: this file *must* end with a .el extension. It will be byte-compiled
+    after it is generated.
+
+  `$DOOMPROFILELOADPATH'
+    A colon-delimited (semi-colon on Windows) list of profile config files or
+    directories under which Doom will search for implicit profiles. See
+    `var:doom-profile-load-path' for its default value.
 
 EXIT CODES:
   0        Successful run

early-init.el

@@ -74,13 +74,18 @@
              (setq user-emacs-directory (expand-file-name init-dir))))
        ;; FIX: Discard the switch to prevent "invalid option" errors later.
        (push (cons "--profile" (lambda (_) (pop argv))) command-switch-alist)
-       ;; Running 'doom sync' will (re)generate a lightweight profile
-       ;; bootstrapper in $EMACSDIR/profiles/init.el, after reading
-       ;; $EMACSDIR/profiles.el, $DOOMDIR/profiles,
-       ;; $XDG_CONFIG_HOME/doom-profiles.el, and ~/.doom-profiles.el. All it
-       ;; needs is for `$DOOMPROFILE' to be set.
+       ;; Running 'doom sync' or 'doom profile sync' (re)generates a light
+       ;; profile loader in $EMACSDIR/profiles/load.el (or
+       ;; $DOOMPROFILELOADFILE), after reading `doom-profile-load-path'. This
+       ;; loader requires `$DOOMPROFILE' be set to function.
        (setenv "DOOMPROFILE" profile)
-       (or (load (expand-file-name (format "profiles/init.%d.elc" emacs-major-version)
+       (or (load (expand-file-name
+                  (format (let ((lfile (getenv-internal "DOOMPROFILELOADFILE")))
+                            (if lfile
+                                (concat (string-remove-suffix ".el" lfile)
+                                        ".%d.elc")
+                              "profiles/load.%d.elc"))
+                          emacs-major-version)
                   user-emacs-directory)
                  'noerror (not init-file-debug) 'nosuffix)
            (user-error "Profiles not initialized yet; run 'doom sync' first"))))

lisp/cli/profiles.el

@@ -38,17 +38,16 @@
   :benchmark t
   (let* ((old-profiles (doom-profiles-read doom-cli-known-profiles-file))
          (new-profiles (doom-profiles-autodetect))
-         (init-file doom-profiles-bootstrap-file)
-         (version (doom-file-read init-file :by 'read :noerror t))
+         (load-file doom-profile-load-file)
+         (version (doom-file-read load-file :by 'read :noerror t))
          (recreate? (or (not reload?) (doom-profiles-outdated-p))))
-    (unless (file-exists-p init-file)
-      (print! (warn "No profile manifest found. Generating one..."))
+    (unless (file-exists-p load-file)
+      (print! (warn "No profile loader found. Generating one..."))
       (print-group! (print! (start "Regenerating it...")))
       (setq recreate? t))
     (unless (equal (or version doom-version) doom-version)
-      (print! (warn "Detected version mismatch in profile manifest (%s != %s)"
-                    version
-                    doom-version))
+      (print! (warn "Detected version mismatch in profile loader (%s != %s)"
+                    version doom-version))
       (print! (start "Generating profile manifest..."))
       (setq recreate? t))
     (print-group!
@@ -70,9 +69,9 @@
               (dolist (p removed) (print! (item "Removed %S") (car p)))
               (dolist (p changed) (print! (item "Changed %S") (car p)))
               (doom-file-write doom-cli-known-profiles-file (list new-profiles) :mode #o600)
-              (doom-profiles-save new-profiles)
-              (print! (success "Regenerated profile bootstrapper: %s")
-                      (path doom-profiles-bootstrap-file)))))))))
+              (doom-profiles-save new-profiles load-file)
+              (print! (success "Regenerated profile loader: %s")
+                      (path load-file)))))))))
 
 
 ;;

lisp/doom-profiles.el

@@ -8,31 +8,37 @@
 ;;; Variables
 
 ;;; File/directory variables
-(defvar doom-profiles-dir doom-data-dir
+(defvar doom-profiles-generated-dir doom-data-dir
   "Where generated profiles are kept.
 
 Profile directories are in the format {data-profiles-dir}/$NAME/@/$VERSION, for
 example: '~/.local/share/doom/_/@/0/'")
 
-(defvar doom-profile-dirs
-  (list (file-name-concat doom-user-dir "profiles")
-        (file-name-concat doom-emacs-dir "profiles"))
-  "A list of directories to search for implicit Doom profiles in.")
-
-(defvar doom-profile-config-files
+(defvar doom-profile-load-path
+  (if-let (path (getenv-internal "DOOMPROFILELOADPATH"))
+      (mapcar #'expand-file-name (split-string-and-unquote path path-separator))
     (list (file-name-concat doom-user-dir "profiles.el")
           (file-name-concat doom-emacs-dir "profiles.el")
           (expand-file-name "doom-profiles.el" (or (getenv "XDG_CONFIG_HOME") "~/.config"))
-        (expand-file-name "~/.doom-profiles.el"))
-  "A list of potential locations for a profiles.el file.
+          (expand-file-name "~/.doom-profiles.el")
+          (file-name-concat doom-user-dir "profiles")
+          (file-name-concat doom-emacs-dir "profiles")))
+  "A list of profile config files or directories that house implicit profiles.
 
-`doom-profiles-initialize' will load and merge all profiles defined in the above
-files, and will write a summary profiles.el to the first entry in this
-variable.")
+`doom-profiles-initialize' loads and merges all profiles defined in the above
+files/directories, then writes a profile load script to
+`doom-profile-load-file'.
 
-(defvar doom-profiles-bootstrap-file
-  (file-name-concat doom-emacs-dir (format "profiles/init.el" emacs-major-version))
-  "Where Doom writes its interactive profile bootstrap script.")
+Can be changed externally by setting $DOOMPROFILELOADPATH to a colon-delimited
+list of paths or profile config files (semi-colon delimited on Windows).")
+
+(defvar doom-profile-load-file
+  (if-let (loader (getenv-internal "DOOMPROFILELOADFILE"))
+      (expand-file-name loader doom-emacs-dir)
+    (file-name-concat doom-emacs-dir (format "profiles/load.el" emacs-major-version)))
+  "Where Doom writes its interactive profile loader script.
+
+Can be changed externally by setting $DOOMPROFILELOADFILE.")
 
 (defvar doom-profile-init-file-name (format "init.%d.el" emacs-major-version)
   "TODO")
@@ -113,21 +119,23 @@ run.")
                           :key #'car)))))))
     (nreverse profiles)))
 
-(defun doom-profiles-autodetect ()
+(defun doom-profiles-autodetect (&optional _internal?)
   "Return all known profiles as a nested alist.
 
-This reads all profiles in `doom-profile-config-files', then reads implicit profiles
-living in `doom-profile-dirs', then caches them in `doom--profiles'. If RELOAD?
-is non-nil, refresh the cache."
-  (doom-profiles-read doom-profile-config-files
-                      doom-profile-dirs))
+This reads all profile configs and directories in `doom-profile-load-path', then
+caches them in `doom--profiles'. If RELOAD? is non-nil, refresh the cache."
+  (doom-profiles-read doom-profile-load-path
+                      ;; TODO: Add in v3
+                      ;; (if internal? doom-profiles-generated-dir)
+                      ))
 
 (defun doom-profiles-outdated-p ()
-  "Return non-nil if files in `doom-profile-loader-file' are outdated."
-  (cl-loop for file in doom-profile-config-files
-           if (or (not (file-exists-p doom-profiles-bootstrap-file))
-                  (file-newer-than-file-p file doom-profiles-bootstrap-file)
-                  (not (equal (doom-file-read doom-profiles-bootstrap-file :by 'read)
+  "Return non-nil if files in `doom-profile-load-file' are outdated."
+  (cl-loop for path in doom-profile-load-path
+           when (string-suffix-p path ".el")
+           if (or (not (file-exists-p doom-profile-load-file))
+                  (file-newer-than-file-p path doom-profile-load-file)
+                  (not (equal (doom-file-read doom-profile-load-file :by 'read)
                               doom-version)))
            return t))
 
@@ -153,7 +161,7 @@ is non-nil, refresh the cache."
 (defun doom-profiles-save (profiles &optional file)
   "Generate a profile bootstrapper for Doom to load at startup."
   (unless file
-    (setq file doom-profiles-bootstrap-file))
+    (setq file doom-profile-load-file))
   (doom-file-write
    file (let ((profilesym (make-symbol "profile"))
               (deferredsym (make-symbol "deferred-vars")))