Remove the "def" indentation heuristic

* lisp/emacs-lisp/lisp-mode.el (lisp-indent-function): Don't
indent function calls with names that that start with "def"
specially (bug#43329).

etc/NEWS

@@ -164,6 +164,26 @@ Emacs buffers, like indentation and the like.  The new ert function
 
 * Incompatible Lisp Changes in Emacs 29.1
 
+---
+** 'def' indentation changes.
+In 'emacs-lisp-mode', forms with a symbol with a name that start with
+"def" have been automatically indented as if they were 'defun'-like
+forms, for instance:
+
+  (defzot 1
+    2 3)
+
+This heuristic has now been removed, and all functions/macros that
+want to be indented this way have to be marked with
+
+  (declare (indent defun))
+
+or the like.  If the function/macro definition itself can't be
+changed, the indentation can also be adjusted by saying something
+like:
+
+  (put 'defzot 'lisp-indent-function 'defun)
+
 ---
 ** The 'inhibit-changing-match-data' variable is now obsolete.
 Instead, functions like 'string-match' and 'looking-at' now take an

lisp/emacs-lisp/lisp-mode.el

@@ -1220,9 +1220,6 @@ Lisp function does not specify a special indentation."
                                        'lisp-indent-function)
 			 (get (intern-soft function) 'lisp-indent-hook)))
 	(cond ((or (eq method 'defun)
-		   (and (null method)
-			(> (length function) 3)
-			(string-match "\\`def" function))
                    ;; Check whether we are in flet-like form.
                    (lisp--local-defform-body-p state))
 	       (lisp-indent-defform state indent-point))

test/lisp/progmodes/elisp-mode-resources/elisp-indents.erts

@@ -57,3 +57,17 @@ Name: defvar-keymap
   :foo bar
   "\r" #'eww-follow-link)
 =-=-=
+
+Name: def-indent1
+
+=-=
+(defzot-does-not-exist 1
+                       2 3)
+=-=-=
+
+Name: def-indent2
+
+=-=
+(define-keymap 1
+  2 3)
+=-=-=