bug#10772: 24.0.93; [patch] Convert tcl-auto-fill-mode to use define-minor-mode

[npostavs]

Xue Fuqiao <xfq@gnu.org> writes:

> +(define-obsolete-function-alias tcl-auto-fill-mode
> +  auto-fill-mode "24.4")

I think making this an alias breaks backwards compatibility needlessly.
I propose just marking it obsolete without changing it:

>From dd1ba59961cc216422349716fcfc62e656076500 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Sat, 1 Apr 2017 21:02:50 -0400
Subject: [PATCH v1] Make tcl-auto-fill-mode obsolete (Bug#10772)

* lisp/progmodes/tcl.el (tcl-auto-fill-mode): Declare obsolete.
* etc/NEWS: Announce it.
---
 etc/NEWS              | 5 +++++
 lisp/progmodes/tcl.el | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 7972511f7a..cbd388b216 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1306,6 +1306,11 @@ window changed size when 'window-size-change-functions' 
are run.
 *** The semantics of 'mouse-autoselect-window' has changed slightly.
 For details see the section "Mouse Window Auto-selection" in the Elisp
 manual.
+
+---
+** 'tcl-auto-fill-mode' is now declared obsolete.  It's functionality
+can be replicated simply by setting 'comment-auto-fill-only-comments'.
+
 
 * Changes in Emacs 26.1 on Non-Free Operating Systems
 
diff --git a/lisp/progmodes/tcl.el b/lisp/progmodes/tcl.el
index 902a5aace0..de0cd50911 100644
--- a/lisp/progmodes/tcl.el
+++ b/lisp/progmodes/tcl.el
@@ -353,8 +353,6 @@ (defvar tcl-mode-hook nil
     Quotes all \"#\" characters that don't correspond to actual
     Tcl comments.  (Useful when editing code not originally created
     with this mode).
-  `tcl-auto-fill-mode'
-    Auto-filling of Tcl comments.
 
 Add functions to the hook with `add-hook':
 
@@ -1413,6 +1411,9 @@ (defun tcl-restart-with-file (file &optional and-go)
 
 (defun tcl-auto-fill-mode (&optional arg)
   "Like `auto-fill-mode', but sets `comment-auto-fill-only-comments'."
+  (declare
+   (obsolete
+    "Use `auto-fill-mode' with `comment-auto-fill-only-comments'." "26.1"))
   (interactive "P")
   (auto-fill-mode arg)
   (if auto-fill-function
-- 
2.11.1