runtime(go): add 'keywordprg' and 'formatprg' to ftplugin

closes: #16804

Signed-off-by: Phạm Bình An <phambinhanctb2004@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/ftplugin/go.vim

@@ -3,6 +3,7 @@
 " Maintainer:	David Barnett (https://github.com/google/vim-ft-go)
 " Last Change:	2014 Aug 16
 " 2024 Jul 16 by Vim Project (add recommended indent style)
+" 2025 Mar 07 by Vim Project (add formatprg and keywordprg option #16804)
 
 if exists('b:did_ftplugin')
   finish
@@ -10,15 +11,39 @@ endif
 let b:did_ftplugin = 1
 
 setlocal formatoptions-=t
+setlocal formatprg=gofmt
 
 setlocal comments=s1:/*,mb:*,ex:*/,://
 setlocal commentstring=//\ %s
+setlocal keywordprg=:GoKeywordPrg
 
-let b:undo_ftplugin = 'setl fo< com< cms<'
+command! -buffer -nargs=* GoKeywordPrg call s:GoKeywordPrg()
+
+let b:undo_ftplugin = 'setl fo< com< cms< fp< kp<'
+                  \ . '| delcommand -buffer GoKeywordPrg'
 
 if get(g:, 'go_recommended_style', 1)
   setlocal noexpandtab softtabstop=0 shiftwidth=0
   let b:undo_ftplugin ..= ' | setl et< sts< sw<'
 endif
 
+if !exists('*' .. expand('<SID>') .. 'GoKeywordPrg')
+  func! s:GoKeywordPrg()
+    let temp_isk = &l:iskeyword
+    setl iskeyword+=.
+    try
+      let cmd = 'go doc -C ' . shellescape(expand('%:h')) . ' ' . shellescape(expand('<cword>'))
+      if has('nvim')
+        exe "term" cmd
+        startinsert
+        tmap <buffer> <Esc> <Cmd>call jobstop(&channel) <Bar> bdelete<CR>
+      else
+        exe '!' . cmd
+      endif
+    finally
+      let &l:iskeyword = temp_isk
+    endtry
+  endfunc
+endif
+
 " vim: sw=2 sts=2 et