fix(surround): adjust s-><Nop> mapping to respect buf+global mappings

Details:
- Although using `vim.fn.maparg()` is concise, it is not a reliable
  source of data about whether or not there is a global mapping.
  In case there is a buffer-local mapping, it can not return information
  about the global mapping.

  Resort to manual iteration through `nvim_get_keymap()` array to deduce
  if there is a mapping with a target LHS.

Author: echasnovski

lua/mini/surround.lua

@@ -2265,10 +2265,17 @@ H.map = function(mode, lhs, rhs, opts)
   if lhs == '' then return end
   opts = vim.tbl_deep_extend('force', { silent = true }, opts or {})
   vim.keymap.set(mode, lhs, rhs, opts)
-  local no_global_s_mapping = vim.fn.maparg('s', mode, false, true).buffer ~= 0
+  local no_global_s_mapping = not H.has_global_mapping(mode, 's')
   if no_global_s_mapping and lhs:find('^s.') ~= nil then vim.keymap.set(mode, 's', '<Nop>') end
 end
 
+H.has_global_mapping = function(mode, lhs)
+  for _, map in ipairs(vim.api.nvim_get_keymap(mode)) do
+    if map.lhs == lhs then return true end
+  end
+  return false
+end
+
 H.get_line_cols = function(line_num) return vim.fn.getline(line_num):len() end
 
 H.string_find = function(s, pattern, init)

tests/test_surround.lua

@@ -248,8 +248,22 @@ T['setup()']['properly handles `config.mappings`'] = function()
   end
   -- - NOTE: `nvim_get_keymap()` return `rhs=''` if it is mapped to `<Nop>`
   --   For absent mapping it would have been `nil`
+  eq(get_global_mapping('n', 's').rhs, '')
   eq(get_global_mapping('x', 's').rhs, '')
-  eq(get_global_mapping('x', 's').rhs, '')
+
+  -- - Should work when there are both buffer-local and global mappings
+  make_clean_state()
+  child.cmd('nmap          s <Cmd>echo 1<CR>')
+  child.cmd('nmap <buffer> s <Cmd>echo 10<CR>')
+  child.cmd('xmap          s <Cmd>echo 2<CR>')
+  child.cmd('xmap <buffer> s <Cmd>echo 20<CR>')
+
+  load_module()
+
+  eq(child.fn.maparg('s', 'n'), '<Cmd>echo 10<CR>')
+  eq(child.fn.maparg('s', 'x'), '<Cmd>echo 20<CR>')
+  eq(get_global_mapping('n', 's').rhs, '<Cmd>echo 1<CR>')
+  eq(get_global_mapping('x', 's').rhs, '<Cmd>echo 2<CR>')
 end
 
 T['update_n_lines()'] = new_set({