chore: godoc border style

autoload/go/doc.vim

@@ -6,6 +6,8 @@
 let s:cpo_save = &cpo
 set cpo&vim
 
+scriptencoding utf-8
+
 let s:buf_nr = -1
 
 function! go#doc#OpenBrowser(...) abort
@@ -61,10 +63,14 @@ function! s:GodocView(newposition, position, content) abort
     if exists('*popup_atcursor') && exists('*popup_clear')
       call popup_clear()
 
+      let borderchars = ['-', '|', '-', '|', '+', '+', '+', '+']
+      if &encoding == "utf-8"
+        let borderchars = ['─', '│', '─', '│', '┌', '┐', '┘', '└']
+      endif
       call popup_atcursor(split(a:content, '\n'), {
             \ 'padding': [1, 1, 1, 1],
-            \ 'borderchars': ['-','|','-','|','+','+','+','+'],
-            \ "border": [1, 1, 1, 1],
+            \ 'borderchars': get(g:, 'go_doc_popup_border', borderchars),
+            \ 'border': [1, 1, 1, 1],
             \ })
     elseif has('nvim') && exists('*nvim_open_win')
       let lines = split(a:content, '\n')

doc/vim-go.txt

@@ -1465,6 +1465,14 @@ Use this option to use the popup-window for |K| and |:GoDoc|, rather than the
   let g:go_doc_popup_window = 0
 <
 
+                                                     *'g:go_doc_popup_border'*
+
+Use this option to custome border chars of the popup-window for |K|
+and |:GoDoc|, Default is empty. Example usage, set the border as rounded:
+>
+  let g:go_doc_popup_border = ['─', '│', '─', '│', '╭', '╮', '╯', '╰']
+<
+
                                                              *'g:go_def_mode'*
 
 Use this option to define the command to be used for |:GoDef|. By default
@@ -1486,7 +1494,7 @@ other packages. Valid options are `gopls` and `guru`. By default it's `gopls`.
 <
                                                       *'g:go_implements_mode'*
 
-Use this option to define the command to be used for |:GoImplements|. 
+Use this option to define the command to be used for |:GoImplements|.
 The Implements feature in gopls is still new and being worked upon.
 Valid options are `gopls` and `guru`. By default it's `guru`.
 >