fix(dir): define "-" (up/parent) mapping earlier #40531

Problem:
The dir.lua "-" mapping cannot be easily overridden (because of autocmd
ordering).

Solution:
- Move it to defaults.lua.
- Also to be extra polite: fall back to builtin `-` motion if the user
  disabled the `dir.lua` plugin.

runtime/doc/vim_diff.txt

@@ -149,6 +149,7 @@ you never want any default mappings, call |:mapclear| early in your config.
 - <C-W> |i_CTRL-W-default|
 - <C-L> |CTRL-L-default|
 - & |&-default|
+- - |dir-mappings|
 - Q |v_Q-default|
 - @ |v_@-default|
 - # |v_#-default|

runtime/lua/vim/_core/defaults.lua

@@ -129,6 +129,13 @@ do
   --- See |&-default|
   vim.keymap.set('n', '&', ':&&<CR>', { desc = ':help &-default' })
 
+  vim.keymap.set('n', '-', function()
+    if vim.fn.maparg('<Plug>(nvim-dir-up)', 'n') ~= '' then
+      return '<Plug>(nvim-dir-up)'
+    end
+    return (vim.v.count == 0 and '' or vim.v.count) .. '-'
+  end, { expr = true, silent = true, desc = 'Open parent directory' })
+
   --- Use Q in Visual mode to execute a macro on each line of the selection. #21422
   --- This only make sense in linewise Visual mode. #28287
   ---

runtime/plugin/dir.lua

@@ -18,10 +18,6 @@ vim.keymap.set('n', '<Plug>(nvim-dir-reload)', function()
   require('nvim.dir')._reload()
 end, { silent = true, desc = 'Reload directory' })
 
-if vim.fn.mapcheck('-', 'n') == '' and vim.fn.hasmapto('<Plug>(nvim-dir-up)', 'n') == 0 then
-  vim.keymap.set('n', '-', '<Plug>(nvim-dir-up)', { silent = true, desc = 'Open parent directory' })
-end
-
 ---@param buf integer
 ---@param path string
 ---@return boolean

test/functional/plugin/dir_spec.lua

@@ -144,9 +144,9 @@ describe('nvim.dir', function()
     assert_directory(root)
   end)
 
-  it('maps - to open the parent directory of the current file', function()
+  it('maps - to open parent directories', function()
     make_fixture()
-    n.clear({ args_rm = { '-u' } })
+    n.clear({ args_rm = { '-u', '--cmd' } })
 
     edit(file)
     feed('-')
@@ -154,6 +154,14 @@ describe('nvim.dir', function()
 
     assert_directory(root)
     line_of('alpha.txt')
+
+    n.clear({ args_rm = { '--cmd' }, args = { '--noplugin' } })
+    api.nvim_buf_set_lines(0, 0, -1, false, { '  alpha', '  beta' })
+    api.nvim_win_set_cursor(0, { 2, 7 })
+    feed('-')
+
+    eq({ 1, 2 }, api.nvim_win_get_cursor(0))
+    eq(false, exec_lua([[return package.loaded['nvim.dir'] ~= nil]]))
   end)
 
   it('uses an absolute buffer name for a relative startup directory argument', function()