runtime: Set b:undo_ftplugin where missing (#12943)

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/ftplugin/hare.vim

@@ -2,26 +2,34 @@
 " Language: Hare
 " Maintainer: Amelia Clarke <me@rsaihe.dev>
 " Previous Maintainer: Drew DeVault <sir@cmpwn.com>
-" Last Updated: 2022-09-21
+" Last Updated: 2022-09-28
+"               2023 Aug 28 by Vim Project (undo_ftplugin)
 
-" Only do this when not done yet for this buffer
 if exists('b:did_ftplugin')
   finish
 endif
-
-" Don't load another plugin for this buffer
 let b:did_ftplugin = 1
 
-setlocal noexpandtab
-setlocal tabstop=8
-setlocal shiftwidth=0
-setlocal softtabstop=0
-setlocal textwidth=80
-setlocal commentstring=//\ %s
+" Formatting settings.
+setlocal formatoptions-=t formatoptions+=croql/
 
-" Set 'formatoptions' to break comment lines but not other lines,
-" and insert the comment leader when hitting <CR> or using "o".
-setlocal fo-=t fo+=croql
+" Miscellaneous.
+setlocal comments=://
+setlocal commentstring=//\ %s
+setlocal suffixesadd=.ha
+
+let b:undo_ftplugin = "setl cms< com< fo< sua<"
+
+" Hare recommended style.
+if get(g:, "hare_recommended_style", 1)
+  setlocal noexpandtab
+  setlocal shiftwidth=8
+  setlocal softtabstop=0
+  setlocal tabstop=8
+  setlocal textwidth=80
+  let b:undo_ftplugin ..= " | setl et< sts< sw< ts< tw<"
+endif
 
 compiler hare
-" vim: tabstop=2 shiftwidth=2 expandtab
+
+" vim: et sw=2 sts=2 ts=8