refactor(lib): replace doom-debugger with advice

Writing a debugger for Elisp is too much hassle. `debug` itself isn't
very customizable without a *lot* of boilerplate, so instead of writing
my own, it's more effective to advise debug instead. Certainly, I don't
do anything with it yet, but I will soon.

lisp/doom-cli.el

@@ -21,12 +21,7 @@
 
   ;; UX: Ensure errors are sufficiently verbose from this point on.
   (when (setq init-file-debug (getenv-internal "DEBUG"))
-    (setq debug-on-error t
+    (setq debug-on-error t))
-          doom-print-level 'debug)
-    (message "Debug mode enabled"))
-
-  ;; FIX: All output via `message' should be seen as debug output.
-  (setq doom-print-message-level 'debug)
 
   ;; HACK: Load `cl' and site files manually to prevent polluting logs and
   ;;   stdout with deprecation and/or file load messages.
@@ -70,7 +65,7 @@
   ;; more presentable, and write them to a file. Cleaner backtraces are better
   ;; UX than the giant wall of text the default debugger throws up.
   (doom-require 'doom-lib 'debug)
-  (setq debugger #'doom-debugger)
+  (if init-file-debug (doom-debug-mode +1))
 
   ;; Then load the rest of Doom's libs eagerly, since autoloads may not be
   ;; generated/loaded yet.

lisp/lib/debug.el

@@ -7,13 +7,13 @@
 
 ;;;###autoload
 (defvar doom-debug-variables
-  '(;; Doom variables
+  `(;; Doom variables
     (doom-print-level . debug)
+    (doom-print-message-level . info)
 
     ;; Emacs variables
     async-debug
     debug-on-error
-    (debugger . doom-debugger)
     garbage-collection-messages
     gcmh-verbose
     init-file-debug
@@ -84,10 +84,29 @@ symbol and CDR is the value to set it to when `doom-debug-mode' is activated.")
 
 
 ;;
-;;; Custom debuggers
+;;; Custom debugger
+
+;; HACK: I advise `debug' instead of changing `debugger' to hide the debugger
+;;   itself from the backtrace. Doing it manually would require reimplementing
+;;   most of `debug', which is a lot of unnecessary work, when I only want to
+;;   decorate the original one slightly.
+(defadvice! doom-debugger-a (fn &rest args)
+  :around #'debug
+  ;; Without `doom-debug-mode', be as vanilla as possible.
+  (if (not doom-debug-mode)
+      (apply fn args)
+    ;; Work around Emacs's heuristic (in eval.c) for detecting errors in the
+    ;; debugger, which would run this handler again on subsequent calls. Taken
+    ;; from `ert--run-test-debugger'.
+    (if (and noninteractive (fboundp 'doom-cli-debugger))
+        (apply #'doom-cli-debugger args)
+      ;; TODO: Write backtraces to file
+      ;; TODO: Write backtrace to a buffer in case recursive error interupts the
+      ;;   debugger (happens more often than it should).
+      (apply fn args))))
 
 (autoload 'backtrace-get-frames "backtrace")
-
+;;;###autoload
 (defun doom-backtrace ()
   "Return a stack trace as a list of `backtrace-frame' objects."
   ;; (let* ((n 0)
@@ -134,23 +153,6 @@ symbol and CDR is the value to set it to when `doom-debug-mode' is activated.")
               backtrace))
       file)))
 
-(defun doom-debugger (&rest args)
-  "Enter `debugger' in interactive sessions, `doom-cli-debugger' otherwise.
-
-Writes backtraces to file and ensures the backtrace is recorded, so the user can
-always access it."
-  (let ((backtrace (doom-backtrace)))
-    ;; Work around Emacs's heuristic (in eval.c) for detecting errors in the
-    ;; debugger, which would run this handler again on subsequent calls. Taken
-    ;; from `ert--run-test-debugger'.
-    (cl-incf num-nonmacro-input-events)
-    (if (and noninteractive (fboundp 'doom-cli-debugger))
-        (apply #'doom-cli-debugger args)
-      ;; TODO Write backtraces to file
-      ;; TODO Write backtrace to a buffer in case recursive error interupts the
-      ;;   debugger (happens more often than it should).
-      (apply #'debug args))))
-
 
 ;;
 ;;; Time-stamped *Message* logs

lisp/lib/print.el

@@ -125,14 +125,14 @@ Accepts `ansi' and `text-properties'. `nil' means don't render styles at all.")
 (defvar doom-print-logging-level 'debug
   "The default logging level used by `doom-log'/`doom-print'.")
 
-(defvar doom-print-message-level 'info
+(defvar doom-print-message-level (if noninteractive 'debug 'info)
   "The default logging level used by `message'.")
 
 (defvar doom-print--levels
   '(debug    ; the system is thinking out loud
     info     ; a FYI; to keep you posted
     warning  ; a dismissable issue that may have reprecussions later
-    error))  ; functionality has been disabled by misbehavior
+    error))  ; functionality has been disabled/broken by misbehavior
 
 (dotimes (i (length doom-print--levels))
   (put (nth i doom-print--levels) 'level i))