vim-patch:9.1.1779: completion: 'autocomplete' cannot be enabled per buffer (#35853)

Problem:  completion: 'autocomplete' cannot be enabled per buffer
          (Tomasz N)
Solution: Make 'autocomplete' global or local to buffer (Girish Palya)

fixes: vim/vim#18320
closes: vim/vim#18333

0208b3e80a

Co-authored-by: Girish Palya <girishji@gmail.com>

runtime/doc/options.txt

@@ -743,7 +743,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 
 			*'autocomplete'* *'ac'* *'noautocomplete'* *'noac'*
 'autocomplete' 'ac'	boolean	(default off)
-			global
+			global or local to buffer |global-local|
 	When on, Vim shows a completion menu as you type, similar to using
 	|i_CTRL-N|, but triggered automatically.  See |ins-autocompletion|.
 

runtime/lua/vim/_meta/options.lua

@@ -117,6 +117,8 @@ vim.go.acd = vim.go.autochdir
 --- @type boolean
 vim.o.autocomplete = false
 vim.o.ac = vim.o.autocomplete
+vim.bo.autocomplete = vim.o.autocomplete
+vim.bo.ac = vim.bo.autocomplete
 vim.go.autocomplete = vim.o.autocomplete
 vim.go.ac = vim.go.autocomplete
 

runtime/optwin.vim

@@ -1,7 +1,7 @@
 " These commands create the option window.
 "
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2025 Aug 23
+" Last Change:	2025 Sep 20
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " If there already is an option window, jump to that one.
@@ -736,6 +736,7 @@ if has("insert_expand")
   call append("$", "\t" .. s:local_to_buffer)
   call <SID>OptionL("cpt")
   call <SID>AddOption("autocomplete", gettext("automatic completion in insert mode"))
+  call append("$", "\t" .. s:global_or_local)
   call <SID>BinOptionG("ac", &ac)
   call <SID>AddOption("autocompletetimeout", gettext("initial decay timeout for 'autocomplete' algorithm"))
   call append("$", " \tset act=" . &act)