fix(ALL): handle :%bdelete if a module has persistent scratch buffer

Details:
- For either performance or user convenience (less increasing of buffer
  ids), some modules create a helper scratch buffer once and reuse it
  whenever it is needed. Like 'mini.clue' and 'mini.notify' use one
  buffer to show its content. Or like 'mini.icons' and 'mini.notify'
  have specific buffers to enable certain kind of behavior.

  Those need to be handled (re-created and re-cached) if the user
  deletes all buffers. This was previously handled for `:%bwipeout`
  case, but not for `:%bdelete`. The difference is that `:bdelete` only
  unloads all buffers without actually deleting them. Among other
  things, this means that all their options are removed. In particular
  'buftype' option is reset making those buffers regular and not scratch
  (`buftype=nofile`) yet still unlisted ("invisible" to the user).

  This can have problematic side effects. Like if the intended scratch
  buffer is used to show text, it will become modified which has
  negative user effects (like `:quit` doesn't work since there are
  modified buffers).

- A solution is to handle buffer deletion not by checking with
  `nvim_buf_is_valid()`, but by a combination of `nvim_buf_is_loaded()`
  check and `pcall(nvim_buf_delete, buf_id, { force = true })` cleanup
  if the buffer is not loaded.

Resolve #2365

Author: echasnovski

lua/mini/animate.lua

@@ -1803,7 +1803,8 @@ H.make_openclose_step = function(action_type, win_id, config)
       end
 
       -- Empty buffer should always be valid (might have been closed by user command)
-      if H.empty_buf_id == nil or not vim.api.nvim_buf_is_valid(H.empty_buf_id) then
+      if H.empty_buf_id == nil or not vim.api.nvim_buf_is_loaded(H.empty_buf_id) then
+        pcall(vim.api.nvim_buf_delete, H.empty_buf_id, { force = true })
         H.empty_buf_id = vim.api.nvim_create_buf(false, true)
         H.set_buf_name(H.empty_buf_id, 'open-close-scratch')
       end

lua/mini/clue.lua

@@ -1719,7 +1719,8 @@ end
 -- Buffer ---------------------------------------------------------------------
 H.buffer_update = function()
   local buf_id = H.state.buf_id
-  if not H.is_valid_buf(buf_id) then
+  if not H.is_loaded_buf(buf_id) then
+    pcall(vim.api.nvim_buf_delete, buf_id, { force = true })
     buf_id = vim.api.nvim_create_buf(false, true)
     H.set_buf_name(buf_id, 'content')
   end
@@ -2008,6 +2009,8 @@ end
 
 H.is_valid_buf = function(buf_id) return type(buf_id) == 'number' and vim.api.nvim_buf_is_valid(buf_id) end
 
+H.is_loaded_buf = function(buf_id) return type(buf_id) == 'number' and vim.api.nvim_buf_is_loaded(buf_id) end
+
 H.is_valid_win = function(win_id) return type(win_id) == 'number' and vim.api.nvim_win_is_valid(win_id) end
 
 H.fit_to_width = function(text, width)

lua/mini/completion.lua

@@ -1762,8 +1762,10 @@ end
 
 -- Helpers for floating windows -----------------------------------------------
 H.ensure_buffer = function(cache, name)
-  if H.is_valid_buf(cache.bufnr) then return end
+  if H.is_loaded_buf(cache.bufnr) then return end
 
+  pcall(vim.api.nvim_buf_delete, cache.bufnr, { force = true })
+  cache.hl_filetype = nil
   local buf_id = vim.api.nvim_create_buf(false, true)
   cache.bufnr = buf_id
   H.set_buf_name(buf_id, name)
@@ -1840,7 +1842,7 @@ H.close_action_window = function(cache)
   cache.win_id = nil
 
   -- For some reason 'buftype' might be reset. Ensure that buffer is scratch.
-  if H.is_valid_buf(cache.bufnr) then vim.bo[cache.bufnr].buftype = 'nofile' end
+  if H.is_loaded_buf(cache.bufnr) then vim.bo[cache.bufnr].buftype = 'nofile' end
 end
 
 -- Utilities ------------------------------------------------------------------
@@ -1853,7 +1855,7 @@ end
 
 H.set_buf_name = function(buf_id, name) vim.api.nvim_buf_set_name(buf_id, 'minicompletion://' .. buf_id .. '/' .. name) end
 
-H.is_valid_buf = function(buf_id) return type(buf_id) == 'number' and vim.api.nvim_buf_is_valid(buf_id) end
+H.is_loaded_buf = function(buf_id) return type(buf_id) == 'number' and vim.api.nvim_buf_is_loaded(buf_id) end
 
 H.is_valid_win = function(win_id) return type(win_id) == 'number' and vim.api.nvim_win_is_valid(win_id) end
 

lua/mini/icons.lua

@@ -2209,7 +2209,8 @@ H.filetype_match = function(filename)
   -- (needed because the function in many ambiguous cases prefers to return
   -- nothing if there is no buffer supplied)
   local buf_id = H.scratch_buf_id
-  if buf_id == nil or not vim.api.nvim_buf_is_valid(buf_id) then
+  if buf_id == nil or not vim.api.nvim_buf_is_loaded(buf_id) then
+    pcall(vim.api.nvim_buf_delete, buf_id, { force = true })
     buf_id = vim.api.nvim_create_buf(false, true)
     H.set_buf_name(buf_id, 'filetype-match-scratch')
     H.scratch_buf_id = buf_id

lua/mini/map.lua

@@ -552,7 +552,8 @@ MiniMap.open = function(opts)
 
   -- Open buffer and window
   local buf_id = MiniMap.current.buf_data.map
-  if buf_id == nil or not vim.api.nvim_buf_is_valid(buf_id) then
+  if buf_id == nil or not vim.api.nvim_buf_is_loaded(buf_id) then
+    pcall(vim.api.nvim_buf_delete, buf_id, { force = true })
     buf_id = H.create_map_buffer()
     MiniMap.current.buf_data.map = buf_id
   end

lua/mini/notify.lua

@@ -483,7 +483,7 @@ MiniNotify.refresh = function()
 
   -- Refresh buffer
   local buf_id = H.cache.buf_id
-  if not H.is_valid_buf(buf_id) then buf_id = H.buffer_create() end
+  if not H.is_loaded_buf(buf_id) then buf_id = H.buffer_create(buf_id) end
   H.buffer_refresh(buf_id, notif_arr)
 
   -- Refresh window
@@ -746,7 +746,8 @@ H.lsp_progress_handler = function(err, result, ctx, config)
 end
 
 -- Buffer ---------------------------------------------------------------------
-H.buffer_create = function()
+H.buffer_create = function(prev_buf_id)
+  pcall(vim.api.nvim_buf_delete, prev_buf_id, { force = true })
   local buf_id = vim.api.nvim_create_buf(false, true)
   H.set_buf_name(buf_id, 'content')
   vim.bo[buf_id].filetype = 'mininotify'
@@ -903,14 +904,15 @@ end
 
 H.set_buf_name = function(buf_id, name) vim.api.nvim_buf_set_name(buf_id, 'mininotify://' .. buf_id .. '/' .. name) end
 
-H.is_valid_buf = function(buf_id) return type(buf_id) == 'number' and vim.api.nvim_buf_is_valid(buf_id) end
+H.is_loaded_buf = function(buf_id) return type(buf_id) == 'number' and vim.api.nvim_buf_is_loaded(buf_id) end
 
 H.is_valid_win = function(win_id) return type(win_id) == 'number' and vim.api.nvim_win_is_valid(win_id) end
 
 H.is_win_in_tabpage = function(win_id) return vim.api.nvim_win_get_tabpage(win_id) == vim.api.nvim_get_current_tabpage() end
 
 H.is_textlock = function()
-  if not H.is_valid_buf(H.cache.textlock_buf_id) then
+  if not H.is_loaded_buf(H.cache.textlock_buf_id) then
+    pcall(vim.api.nvim_buf_delete, H.cache.textlock_buf_id, { force = true })
     H.cache.textlock_buf_id = vim.api.nvim_create_buf(false, true)
     H.set_buf_name(H.cache.textlock_buf_id, 'textlock-check-scratch')
   end

tests/test_animate.lua

@@ -2497,6 +2497,32 @@ T['Open']['triggers done event'] = function()
   eq(child.lua_get('_G.inside_done_event'), true)
 end
 
+T['Open']['handles deleting all buffers'] = function()
+  child.bo.modified = false
+  local validate = function()
+    child.cmd('topleft vertical new')
+    sleep(small_time)
+
+    -- Special helper buffer should be always present and work as expected
+    local helper_buf_id, ref_pattern = nil, '^minianimate://%d+/open%-close%-scratch$'
+    for _, buf_id in ipairs(child.api.nvim_list_bufs()) do
+      if string.find(child.api.nvim_buf_get_name(buf_id), ref_pattern) ~= nil then helper_buf_id = buf_id end
+    end
+    eq(type(helper_buf_id), 'number')
+    eq(child.api.nvim_get_option_value('modified', { buf = helper_buf_id }), false)
+
+    sleep(3 * step_time + small_time)
+  end
+
+  validate()
+
+  child.cmd('%bwipeout')
+  validate()
+
+  child.cmd('%bdelete')
+  validate()
+end
+
 T['Open']['respects `vim.{g,b}.minianimate_disable`'] = new_set({
   parametrize = { { 'g' }, { 'b' } },
 }, {

tests/test_clue.lua

@@ -1790,6 +1790,31 @@ T['Showing keys']['does not trigger unnecessary events'] = function()
   eq(child.lua_get('_G.n_events'), vim.NIL)
 end
 
+T['Showing keys']['handles deleting all buffers'] = function()
+  make_test_map('n', '<Space>aa')
+  load_module({ triggers = { { mode = 'n', keys = '<Space>' } }, window = { delay = 0 } })
+
+  local validate = function()
+    type_keys(' ')
+    type_keys('<Esc>')
+
+    -- Special helper buffer should be always present and work as expected
+    local helper_buf_id, ref_pattern = nil, '^miniclue://%d+/content$'
+    for _, buf_id in ipairs(child.api.nvim_list_bufs()) do
+      if string.find(child.api.nvim_buf_get_name(buf_id), ref_pattern) ~= nil then helper_buf_id = buf_id end
+    end
+    eq(type(helper_buf_id), 'number')
+    eq(child.api.nvim_get_option_value('modified', { buf = helper_buf_id }), false)
+  end
+
+  validate()
+
+  child.cmd('%bwipeout')
+  validate()
+  child.cmd('%bdelete')
+  validate()
+end
+
 T['Showing keys']['respects `vim.b.miniclue_config`'] = function()
   make_test_map('n', '<Space>a')
   load_module({ triggers = { { mode = 'n', keys = '<Space>' } }, window = { delay = 0 } })

tests/test_completion.lua

@@ -128,6 +128,17 @@ local validate_single_floating_win = function(opts)
   end
 end
 
+local validate_helper_buf = function(name_suffix)
+  -- Special helper buffer should be always present and work as expected
+  local helper_buf_id, ref_pattern = nil, '^minicompletion://%d+/' .. vim.pesc(name_suffix) .. '$'
+  for _, buf_id in ipairs(child.api.nvim_list_bufs()) do
+    if string.find(child.api.nvim_buf_get_name(buf_id), ref_pattern) then helper_buf_id = buf_id end
+  end
+  eq(type(helper_buf_id), 'number')
+  eq(child.api.nvim_get_option_value('modified', { buf = helper_buf_id }), false)
+  return helper_buf_id
+end
+
 -- Time constants
 local default_completion_delay, default_info_delay, default_signature_delay = 100, 100, 50
 local small_time = helpers.get_time_const(10)
@@ -1875,6 +1886,32 @@ T['Information window']['handles outdated scheduled showing'] = function()
   eq(child.cmd_capture('messages'), '')
 end
 
+T['Information window']['handles deleting all buffers'] = function()
+  local validate = function()
+    new_buffer()
+    mock_lsp()
+    validate_info_win(default_info_delay)
+    local helper_buf_id = validate_helper_buf('item-info')
+
+    -- Should highlight with attached markdown tree-sitter parser
+    child.lua('_G.helper_buf_id = ' .. helper_buf_id)
+    eq(child.lua_get('vim.treesitter.get_parser(_G.helper_buf_id, "markdown") ~= nil', { helper_buf_id }), true)
+
+    child.ensure_normal_mode()
+    for _, buf_id in ipairs(child.api.nvim_list_bufs()) do
+      child.api.nvim_set_option_value('modified', false, { buf = buf_id })
+    end
+  end
+
+  validate()
+
+  child.cmd('%bwipeout')
+  validate()
+
+  child.cmd('%bdelete')
+  validate()
+end
+
 T['Information window']['respects `vim.{g,b}.minicompletion_disable`'] = new_set({
   parametrize = { { 'g' }, { 'b' } },
 }, {
@@ -2154,15 +2191,30 @@ T['Signature help']['is closed when forced outside of Insert mode'] = new_set(
   }
 )
 
-T['Signature help']['handles all buffer wipeout'] = function()
-  validate_signature_win(default_signature_delay)
-  child.ensure_normal_mode()
+T['Signature help']['handles deleting all buffers'] = function()
+  local validate = function()
+    new_buffer()
+    child.bo.filetype = 'aaa'
+    mock_lsp()
+    validate_signature_win(default_signature_delay)
+    local helper_buf_id = validate_helper_buf('signature-help')
 
-  child.cmd('%bw!')
-  new_buffer()
-  mock_lsp()
+    -- Should highlight with custom syntax
+    eq(child.api.nvim_get_option_value('syntax', { buf = helper_buf_id }), 'aaa')
 
-  validate_signature_win(default_signature_delay)
+    child.ensure_normal_mode()
+    for _, buf_id in ipairs(child.api.nvim_list_bufs()) do
+      child.api.nvim_set_option_value('modified', false, { buf = buf_id })
+    end
+  end
+
+  validate()
+
+  child.cmd('%bwipeout')
+  validate()
+
+  child.cmd('%bdelete')
+  validate()
 end
 
 T['Signature help']['respects `vim.{g,b}.minicompletion_disable`'] = new_set({

tests/test_icons.lua

@@ -653,16 +653,28 @@ T['get()']['can be used without `setup()`'] = function()
   eq(child.lua_get('{ require("mini.icons").get("default", "file") }'), { '󰈔', 'MiniIconsGrey', false })
 end
 
-T['get()']['can be used after deleting all buffers'] = function()
+T['get()']['handles deleting all buffers'] = function()
   -- As `vim.filetype.match()` requries a buffer to be more useful, make sure
-  -- that this cached buffer is persistent
+  -- that there is a persistent helper buffer
+  local validate = function()
+    local helper_buf_id, ref_pattern = nil, '^miniicons://%d+/filetype%-match%-scratch$'
+    for _, buf_id in ipairs(child.api.nvim_list_bufs()) do
+      if string.find(child.api.nvim_buf_get_name(buf_id), ref_pattern) ~= nil then helper_buf_id = buf_id end
+    end
+    eq(type(helper_buf_id), 'number')
+    eq(child.api.nvim_get_option_value('modified', { buf = helper_buf_id }), false)
+  end
+
   eq(get('file', 'hello.xpm'), { '󰍹', 'MiniIconsYellow', false })
-  -- The helper scratch buffer should be properly named
-  eq(child.api.nvim_buf_get_name(2), 'miniicons://2/filetype-match-scratch')
+  validate()
 
   child.cmd('%bwipeout')
   eq(get('file', 'hello.tcsh'), { '', 'MiniIconsAzure', false })
-  eq(child.api.nvim_buf_get_name(3), 'miniicons://3/filetype-match-scratch')
+  validate()
+
+  child.cmd('%bdelete')
+  eq(get('file', 'hello.zsh'), { '', 'MiniIconsGreen', false })
+  validate()
 end
 
 T['get()']['uses width one glyphs'] = function()