fix(runtime): add remaining missing commentstrings

listen_addr cannot be NULL at this point.

runtime/doc/lua.txt

@@ -2230,6 +2230,12 @@ vim.tbl_count({t})                                           *vim.tbl_count()*
 vim.tbl_deep_extend({behavior}, {...})                 *vim.tbl_deep_extend()*
     Merges recursively two or more tables.
 
+    Only values that are empty tables or tables that are not |lua-list|s
+    (indexed by consecutive integers starting from 1) are merged recursively.
+    This is useful for merging nested tables like default and user
+    configurations where lists should be treated as literals (i.e., are
+    overwritten instead of merged).
+
     Parameters: ~
       • {behavior}  (`'error'|'keep'|'force'`) Decides what to do if a key is
                     found in more than one map:

runtime/doc/news.txt

@@ -214,9 +214,6 @@ These existing features changed their behavior.
   more emoji characters than before, including those encoded with multiple
   emoji codepoints combined with ZWJ (zero width joiner) codepoints.
 
-• |vim.tbl_deep_extend()| no longer ignores any values for which |vim.isarray()|
-  returns `true`.
-
 ==============================================================================
 REMOVED FEATURES                                                 *news-removed*
 

runtime/doc/options.txt

@@ -1129,9 +1129,9 @@ A jump table for the options with a short description can be found at |Q_op|.
 		list:{n}    Adds an additional indent for lines that match a
 			    numbered or bulleted list (using the
 			    'formatlistpat' setting).
-		list:-1	    Uses the length of a match with 'formatlistpat'
-			    for indentation.
 			    (default: 0)
+		list:-1	    Uses the width of a match with 'formatlistpat' for
+			    indentation.
 		column:{n}  Indent at column {n}. Will overrule the other
 			    sub-options. Note: an additional indent may be
 			    added for the 'showbreak' setting.

runtime/doc/windows.txt

@@ -53,11 +53,17 @@ active		  yes		 yes		  'a'
 hidden		  no		 yes		  'h'
 inactive	  no		 no		  ' '
 
-Note: All CTRL-W commands can also be executed with |:wincmd|, for those
-places where a Normal mode command can't be used or is inconvenient.
+							*buffer-reuse*
+Each buffer has a unique number and the number will not change within a Vim
+session.  The |bufnr()| and |bufname()| functions can be used to convert
+between a buffer name and the buffer number.  There is one exception: if a new
+empty buffer is created and it is not modified, the buffer will be re-used
+when loading another file into that buffer. This also means the buffer number
+will not change.
 
 The main Vim window can hold several split windows.  There are also tab pages
 |tab-page|, each of which can hold multiple windows.
+
 					*window-ID* *winid* *windowid*
 Each window has a unique identifier called the window ID.  This identifier
 will not change within a Vim session. The |win_getid()| and |win_id2tabwin()|
@@ -69,9 +75,6 @@ across tabs.  For most functions that take a window ID or a window number, the
 window number only applies to the current tab, while the window ID can refer
 to a window in any tab.
 
-Each buffer has a unique number and the number will not change within a Vim
-session.  The |bufnr()| and |bufname()| functions can be used to convert
-between a buffer name and the buffer number.
 
 ==============================================================================
 2. Starting Vim						*windows-starting*
@@ -468,6 +471,10 @@ These commands can also be executed with ":wincmd":
 			:exe nr .. "wincmd w"
 <		This goes to window "nr".
 
+Note: All CTRL-W commands can also be executed with |:wincmd|, for those
+places where a Normal mode command can't be used or is inconvenient (e.g.
+in a browser-based terminal).
+
 ==============================================================================
 5. Moving windows around				*window-moving*
 

runtime/ftplugin/arduino.lua

@@ -1,3 +1 @@
 vim.bo.commentstring = '// %s'
-
-vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl commentstring<'

runtime/ftplugin/c.lua

@@ -11,4 +11,4 @@ if vim.fn.isdirectory('/usr/include') == 1 then
   ]])
 end
 
-vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl path< commentstring< define< include<'
+vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl path<'

runtime/ftplugin/ch.lua

@@ -1,3 +1 @@
 vim.bo.commentstring = '// %s'
-
-vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl commentstring<'

runtime/ftplugin/d.lua

@@ -1,3 +1,3 @@
 vim.bo.commentstring = '// %s'
 
-vim.b.undo_ftplugin = (vim.b.undo_ftplugin or '') .. '\n setl commentstring<'
+vim.b.undo_ftplugin = 'setl commentstring<'

runtime/ftplugin/dart.lua

@@ -1,3 +0,0 @@
-vim.bo.commentstring = '// %s'
-
-vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl commentstring<'

runtime/ftplugin/glsl.lua

@@ -1,3 +1,3 @@
 vim.bo.commentstring = '// %s'
 
-vim.b.undo_ftplugin = (vim.b.undo_ftplugin or '') .. '\n setl commentstring<'
+vim.b.undo_ftplugin = 'setl commentstring<'

runtime/ftplugin/indent.lua

@@ -1,3 +1 @@
 vim.bo.commentstring = '// %s'
-
-vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl commentstring<'

runtime/ftplugin/objc.lua

@@ -1,3 +1 @@
 vim.bo.commentstring = '// %s'
-
-vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl commentstring<'

runtime/ftplugin/v.lua

@@ -1,3 +0,0 @@
-vim.bo.commentstring = '// %s'
-
-vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl commentstring<'

runtime/ftplugin/xs.lua

@@ -1,3 +1 @@
 vim.bo.commentstring = '// %s'
-
-vim.b.undo_ftplugin = vim.b.undo_ftplugin .. ' | setl commentstring<'

runtime/lua/tohtml.lua

@@ -1293,9 +1293,25 @@ local function opt_to_global_state(opt, title)
   local fonts = {}
   if opt.font then
     fonts = type(opt.font) == 'string' and { opt.font } or opt.font --[[@as (string[])]]
+    for i, v in pairs(fonts) do
+      fonts[i] = ('"%s"'):format(v)
+    end
   elseif vim.o.guifont:match('^[^:]+') then
-    table.insert(fonts, vim.o.guifont:match('^[^:]+'))
+    -- Example:
+    -- Input: "Font,Escape\,comma, Ignore space after comma"
+    -- Output: { "Font","Escape,comma","Ignore space after comma" }
+    local prev = ''
+    for name in vim.gsplit(vim.o.guifont:match('^[^:]+'), ',', { trimempty = true }) do
+      if vim.endswith(name, '\\') then
+        prev = prev .. vim.trim(name:sub(1, -2) .. ',')
+      elseif vim.trim(name) ~= '' then
+        table.insert(fonts, ('"%s%s"'):format(prev, vim.trim(name)))
+        prev = ''
+      end
+    end
   end
+  -- Generic family names (monospace here) must not be quoted
+  -- because the browser recognizes them as font families.
   table.insert(fonts, 'monospace')
   --- @type vim.tohtml.state.global
   local state = {

runtime/lua/vim/_meta/options.lua

@@ -558,9 +558,9 @@ vim.wo.bri = vim.wo.breakindent
 --- 	list:{n}    Adds an additional indent for lines that match a
 --- 		    numbered or bulleted list (using the
 --- 		    'formatlistpat' setting).
---- 	list:-1	    Uses the length of a match with 'formatlistpat'
---- 		    for indentation.
 --- 		    (default: 0)
+--- 	list:-1	    Uses the width of a match with 'formatlistpat' for
+--- 		    indentation.
 --- 	column:{n}  Indent at column {n}. Will overrule the other
 --- 		    sub-options. Note: an additional indent may be
 --- 		    added for the 'showbreak' setting.

runtime/lua/vim/lsp/inlay_hint.lua

@@ -77,12 +77,7 @@ function M.on_inlayhint(err, result, ctx, _)
     local col = position.character
     if col > 0 then
       local line = lines[position.line + 1] or ''
-      local ok, convert_result
-      ok, convert_result = pcall(util._str_byteindex_enc, line, col, client.offset_encoding)
-      if ok then
-        return convert_result
-      end
-      return math.min(#line, col)
+      return util._str_byteindex_enc(line, col, client.offset_encoding)
     end
     return col
   end

runtime/lua/vim/lsp/semantic_tokens.lua

@@ -140,12 +140,7 @@ local function tokens_to_ranges(data, bufnr, client, request)
     local function _get_byte_pos(col)
       if col > 0 then
         local buf_line = lines[line + 1] or ''
-        local ok, result
-        ok, result = pcall(util._str_byteindex_enc, buf_line, col, client.offset_encoding)
-        if ok then
-          return result
-        end
-        return math.min(#buf_line, col)
+        return util._str_byteindex_enc(buf_line, col, client.offset_encoding)
       end
       return col
     end

runtime/lua/vim/lsp/util.lua

@@ -147,6 +147,12 @@ end
 ---@param encoding string utf-8|utf-16|utf-32| defaults to utf-16
 ---@return integer byte (utf-8) index of `encoding` index `index` in `line`
 function M._str_byteindex_enc(line, index, encoding)
+  local len = vim.fn.strlen(line)
+  if index > len then
+    -- LSP spec: if character > line length, default to the line length.
+    -- https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#position
+    return len
+  end
   if not encoding then
     encoding = 'utf-16'
   end
@@ -166,7 +172,6 @@ function M._str_byteindex_enc(line, index, encoding)
 end
 
 local _str_utfindex_enc = M._str_utfindex_enc
-local _str_byteindex_enc = M._str_byteindex_enc
 
 --- Replaces text in a range with new text.
 ---
@@ -334,12 +339,7 @@ local function get_line_byte_from_position(bufnr, position, offset_encoding)
   -- character
   if col > 0 then
     local line = get_line(bufnr, position.line) or ''
-    local ok, result
-    ok, result = pcall(_str_byteindex_enc, line, col, offset_encoding)
-    if ok then
-      return result
-    end
-    return math.min(#line, col)
+    return M._str_byteindex_enc(line, col, offset_encoding or 'utf-16')
   end
   return col
 end
@@ -436,14 +436,15 @@ function M.apply_text_edits(text_edits, bufnr, offset_encoding)
         e.end_col = last_line_len
         has_eol_text_edit = true
       else
-        -- If the replacement is over the end of a line (i.e. e.end_col is out of bounds and the
+        -- If the replacement is over the end of a line (i.e. e.end_col is equal to the line length and the
         -- replacement text ends with a newline We can likely assume that the replacement is assumed
         -- to be meant to replace the newline with another newline and we need to make sure this
         -- doesn't add an extra empty line. E.g. when the last line to be replaced contains a '\r'
         -- in the file some servers (clangd on windows) will include that character in the line
         -- while nvim_buf_set_text doesn't count it as part of the line.
         if
-          e.end_col > last_line_len
+          e.end_col >= last_line_len
+          and text_edit.range['end'].character > e.end_col
           and #text_edit.newText > 0
           and string.sub(text_edit.newText, -1) == '\n'
         then
@@ -1795,17 +1796,9 @@ function M.locations_to_items(locations, offset_encoding)
       local row = pos.line
       local end_row = end_pos.line
       local line = lines[row] or ''
-      local line_len = vim.fn.strcharlen(line)
       local end_line = lines[end_row] or ''
-      local end_line_len = vim.fn.strcharlen(end_line)
-      -- LSP spec: if character > line length, default to the line length.
-      -- https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#position
-      local col = pos.character <= line_len
-          and M._str_byteindex_enc(line, pos.character, offset_encoding)
-        or line_len
-      local end_col = end_pos.character <= end_line_len
-          and M._str_byteindex_enc(end_line, end_pos.character, offset_encoding)
-        or end_line_len
+      local col = M._str_byteindex_enc(line, pos.character, offset_encoding)
+      local end_col = M._str_byteindex_enc(end_line, end_pos.character, offset_encoding)
 
       table.insert(items, {
         filename = filename,

runtime/lua/vim/shared.lua

@@ -354,6 +354,12 @@ function vim.tbl_isempty(t)
   return next(t) == nil
 end
 
+--- We only merge empty tables or tables that are not list-like (indexed by consecutive integers
+--- starting from 1)
+local function can_merge(v)
+  return type(v) == 'table' and (vim.tbl_isempty(v) or not vim.islist(v))
+end
+
 --- Recursive worker for tbl_extend
 --- @param behavior 'error'|'keep'|'force'
 --- @param deep_extend boolean
@@ -368,7 +374,7 @@ local function tbl_extend_rec(behavior, deep_extend, ...)
     local tbl = select(i, ...) --[[@as table<any,any>]]
     if tbl then
       for k, v in pairs(tbl) do
-        if deep_extend and type(v) == 'table' and type(ret[k]) == 'table' then
+        if deep_extend and can_merge(v) and can_merge(ret[k]) then
           ret[k] = tbl_extend_rec(behavior, true, ret[k], v)
         elseif behavior ~= 'force' and ret[k] ~= nil then
           if behavior == 'error' then
@@ -421,6 +427,11 @@ end
 
 --- Merges recursively two or more tables.
 ---
+--- Only values that are empty tables or tables that are not |lua-list|s (indexed by consecutive
+--- integers starting from 1) are merged recursively. This is useful for merging nested tables
+--- like default and user configurations where lists should be treated as literals (i.e., are
+--- overwritten instead of merged).
+---
 ---@see |vim.tbl_extend()|
 ---
 ---@generic T1: table

runtime/lua/vim/ui.lua

@@ -152,14 +152,14 @@ function M.open(path)
     else
       return nil, 'vim.ui.open: rundll32 not found'
     end
-  elseif vim.fn.executable('wslview') == 1 then
-    cmd = { 'wslview', path }
-  elseif vim.fn.executable('explorer.exe') == 1 then
-    cmd = { 'explorer.exe', path }
   elseif vim.fn.executable('xdg-open') == 1 then
     cmd = { 'xdg-open', path }
     opts.stdout = false
     opts.stderr = false
+  elseif vim.fn.executable('wslview') == 1 then
+    cmd = { 'wslview', path }
+  elseif vim.fn.executable('explorer.exe') == 1 then
+    cmd = { 'explorer.exe', path }
   else
     return nil, 'vim.ui.open: no handler found (tried: wslview, explorer.exe, xdg-open)'
   end

src/nvim/api/vim.c

@@ -28,6 +28,7 @@
 #include "nvim/cursor.h"
 #include "nvim/decoration.h"
 #include "nvim/drawscreen.h"
+#include "nvim/edit.h"
 #include "nvim/errors.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"

src/nvim/change.c

@@ -756,10 +756,8 @@ void ins_char_bytes(char *buf, size_t charlen)
     // put back when BS is used.  The bytes of a multi-byte character are
     // done the other way around, so that the first byte is popped off
     // first (it tells the byte length of the character).
-    replace_push(NUL);
-    for (size_t i = 0; i < oldlen; i++) {
-      i += (size_t)replace_push_mb(oldp + col + i) - 1;
-    }
+    replace_push_nul();
+    replace_push(oldp + col, oldlen);
   }
 
   char *newp = xmalloc(linelen + newlen - oldlen);
@@ -1137,12 +1135,10 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
     // on the line onto the replace stack.  We'll push any other characters
     // that might be replaced at the start of the next line (due to
     // autoindent etc) a bit later.
-    replace_push(NUL);      // Call twice because BS over NL expects it
-    replace_push(NUL);
+    replace_push_nul();      // Call twice because BS over NL expects it
+    replace_push_nul();
     p = saved_line + curwin->w_cursor.col;
-    while (*p != NUL) {
-      p += replace_push_mb(p);
-    }
+    replace_push(p, strlen(p));
     saved_line[curwin->w_cursor.col] = NUL;
   }
 
@@ -1691,13 +1687,13 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
     // stack, preceded by a NUL, so they can be put back when a BS is
     // entered.
     if (REPLACE_NORMAL(State)) {
-      replace_push(NUL);            // end of extra blanks
+      replace_push_nul();            // end of extra blanks
     }
     if (curbuf->b_p_ai || (flags & OPENLINE_DELSPACES)) {
       while ((*p_extra == ' ' || *p_extra == '\t')
              && !utf_iscomposing_first(utf_ptr2char(p_extra + 1))) {
         if (REPLACE_NORMAL(State)) {
-          replace_push(*p_extra);
+          replace_push(p_extra, 1);  // always ascii, len = 1
         }
         p_extra++;
         less_cols_off++;
@@ -1794,7 +1790,7 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
     // must be a NUL on the replace stack, for when it is deleted with BS
     if (REPLACE_NORMAL(State)) {
       for (colnr_T n = 0; n < curwin->w_cursor.col; n++) {
-        replace_push(NUL);
+        replace_push_nul();
       }
     }
     newcol += curwin->w_cursor.col;
@@ -1808,7 +1804,7 @@ bool open_line(int dir, int flags, int second_line_indent, bool *did_do_comment)
   // must be a NUL on the replace stack, for when it is deleted with BS.
   if (REPLACE_NORMAL(State)) {
     while (lead_len-- > 0) {
-      replace_push(NUL);
+      replace_push_nul();
     }
   }
 

src/nvim/edit.c

@@ -136,6 +136,8 @@ static TriState dont_sync_undo = kFalse;  // CTRL-G U prevents syncing undo
 
 static linenr_T o_lnum = 0;
 
+static kvec_t(char) replace_stack = KV_INITIAL_VALUE;
+
 static void insert_enter(InsertState *s)
 {
   s->did_backspace = true;
@@ -1618,9 +1620,8 @@ void undisplay_dollar(void)
 /// type == INDENT_SET   set indent to "amount"
 ///
 /// @param round               if true, round the indent to 'shiftwidth' (only with _INC and _Dec).
-/// @param replaced            replaced character, put on replace stack
 /// @param call_changed_bytes  call changed_bytes()
-void change_indent(int type, int amount, int round, int replaced, bool call_changed_bytes)
+void change_indent(int type, int amount, int round, bool call_changed_bytes)
 {
   int insstart_less;                    // reduction for Insstart.col
   colnr_T orig_col = 0;                 // init for GCC
@@ -1767,12 +1768,8 @@ void change_indent(int type, int amount, int round, int replaced, bool call_chan
       replace_join(0);              // remove a NUL from the replace stack
       start_col--;
     }
-    while (start_col < (int)curwin->w_cursor.col || replaced) {
-      replace_push(NUL);
-      if (replaced) {
-        replace_push(replaced);
-        replaced = NUL;
-      }
+    while (start_col < (int)curwin->w_cursor.col) {
+      replace_push_nul();
       start_col++;
     }
   }
@@ -2325,7 +2322,7 @@ int stop_arrow(void)
 static void stop_insert(pos_T *end_insert_pos, int esc, int nomove)
 {
   stop_redo_ins();
-  replace_flush();              // abandon replace stack
+  kv_destroy(replace_stack);  // abandon replace stack (reinitializes)
 
   // Save the inserted text for later redo with ^@ and CTRL-A.
   // Don't do it when "restart_edit" was set and nothing was inserted,
@@ -2802,57 +2799,51 @@ static bool echeck_abbr(int c)
 // that the NL replaced.  The extra one stores the characters after the cursor
 // that were deleted (always white space).
 
-static uint8_t *replace_stack = NULL;
-static ssize_t replace_stack_nr = 0;           // next entry in replace stack
-static ssize_t replace_stack_len = 0;          // max. number of entries
-
 /// Push character that is replaced onto the replace stack.
 ///
 /// replace_offset is normally 0, in which case replace_push will add a new
 /// character at the end of the stack.  If replace_offset is not 0, that many
 /// characters will be left on the stack above the newly inserted character.
 ///
-/// @param c character that is replaced (NUL is none)
-void replace_push(int c)
+/// @param str character that is replaced (NUL is none)
+/// @param len length of character in bytes
+void replace_push(char *str, size_t len)
 {
-  if (replace_stack_nr < replace_offset) {  // nothing to do
+  // TODO(bfredl): replace_offset is suss af, if we don't need it, this
+  // function is just kv_concat() :p
+  if (kv_size(replace_stack) < (size_t)replace_offset) {  // nothing to do
     return;
   }
 
-  if (replace_stack_len <= replace_stack_nr) {
-    replace_stack_len += 50;
-    replace_stack = xrealloc(replace_stack, (size_t)replace_stack_len);
-  }
-  uint8_t *p = replace_stack + replace_stack_nr - replace_offset;
+  kv_ensure_space(replace_stack, len);
+
+  char *p = replace_stack.items + kv_size(replace_stack) - replace_offset;
   if (replace_offset) {
-    memmove(p + 1, p, (size_t)replace_offset);
+    memmove(p + len, p, (size_t)replace_offset);
   }
-  *p = (uint8_t)c;
-  replace_stack_nr++;
+  memcpy(p, str, len);
+  kv_size(replace_stack) += len;
 }
 
-/// Push a character onto the replace stack.  Handles a multi-byte character in
-/// reverse byte order, so that the first byte is popped off first.
-///
-/// @return  the number of bytes done (includes composing characters).
-int replace_push_mb(char *p)
+/// push NUL as separator between entries in the stack
+void replace_push_nul(void)
 {
-  int l = utfc_ptr2len(p);
-
-  // TODO(bfredl): stop doing this insantity and instead use utf_head_off() when popping.
-  // or just keep a secondary array with char byte lenghts
-  for (int j = l - 1; j >= 0; j--) {
-    replace_push(p[j]);
-  }
-  return l;
+  replace_push("", 1);
 }
 
-/// Pop one item from the replace stack.
+/// Check top of replace stack, pop it if it was NUL
 ///
-/// @return -1 if stack is empty, replaced character or NUL otherwise
-static int replace_pop(void)
+/// when a non-NUL byte is found, use mb_replace_pop_ins() to
+/// pop one complete multibyte character.
+///
+/// @return -1 if stack is empty, last byte of char or NUL otherwise
+static int replace_pop_if_nul(void)
 {
-  return (replace_stack_nr == 0) ? -1 : (int)replace_stack[--replace_stack_nr];
+  int ch = (kv_size(replace_stack)) ? (uint8_t)kv_A(replace_stack, kv_size(replace_stack) - 1) : -1;
+  if (ch == NUL) {
+    kv_size(replace_stack)--;
+  }
+  return ch;
 }
 
 /// Join the top two items on the replace stack.  This removes to "off"'th NUL
@@ -2861,11 +2852,11 @@ static int replace_pop(void)
 /// @param off  offset for which NUL to remove
 static void replace_join(int off)
 {
-  for (ssize_t i = replace_stack_nr; --i >= 0;) {
-    if (replace_stack[i] == NUL && off-- <= 0) {
-      replace_stack_nr--;
-      memmove(replace_stack + i, replace_stack + i + 1,
-              (size_t)(replace_stack_nr - i));
+  for (ssize_t i = (ssize_t)kv_size(replace_stack); --i >= 0;) {
+    if (kv_A(replace_stack, i) == NUL && off-- <= 0) {
+      kv_size(replace_stack)--;
+      memmove(&kv_A(replace_stack, i), &kv_A(replace_stack, i + 1),
+              (kv_size(replace_stack) - (size_t)i));
       return;
     }
   }
@@ -2875,72 +2866,25 @@ static void replace_join(int off)
 /// before the cursor.  Can only be used in MODE_REPLACE or MODE_VREPLACE state.
 static void replace_pop_ins(void)
 {
-  int cc;
   int oldState = State;
 
   State = MODE_NORMAL;                       // don't want MODE_REPLACE here
-  while ((cc = replace_pop()) > 0) {
-    mb_replace_pop_ins(cc);
+  while ((replace_pop_if_nul()) > 0) {
+    mb_replace_pop_ins();
     dec_cursor();
   }
   State = oldState;
 }
 
-// Insert bytes popped from the replace stack. "cc" is the first byte.  If it
-// indicates a multi-byte char, pop the other bytes too.
-static void mb_replace_pop_ins(int cc)
+/// Insert multibyte char popped from the replace stack.
+///
+/// caller must already have checked the top of the stack is not NUL!!
+static void mb_replace_pop_ins(void)
 {
-  int n;
-  uint8_t buf[MB_MAXBYTES + 1];
-
-  if ((n = MB_BYTE2LEN(cc)) > 1) {
-    buf[0] = (uint8_t)cc;
-    for (int i = 1; i < n; i++) {
-      buf[i] = (uint8_t)replace_pop();
-    }
-    ins_bytes_len((char *)buf, (size_t)n);
-  } else {
-    ins_char(cc);
-  }
-
-  // Handle composing chars.
-  while (true) {
-    int c = replace_pop();
-    if (c == -1) {                // stack empty
-      break;
-    }
-    if ((n = MB_BYTE2LEN(c)) == 1) {
-      // Not a multi-byte char, put it back.
-      replace_push(c);
-      break;
-    }
-
-    buf[0] = (uint8_t)c;
-    assert(n > 1);
-    for (int i = 1; i < n; i++) {
-      buf[i] = (uint8_t)replace_pop();
-    }
-    // TODO(bfredl): by fixing replace_push_mb, upgrade to use
-    // the new composing algorithm
-    if (utf_iscomposing_legacy(utf_ptr2char((char *)buf))) {
-      ins_bytes_len((char *)buf, (size_t)n);
-    } else {
-      // Not a composing char, put it back.
-      for (int i = n - 1; i >= 0; i--) {
-        replace_push(buf[i]);
-      }
-      break;
-    }
-  }
-}
-
-// make the replace stack empty
-// (called when exiting replace mode)
-static void replace_flush(void)
-{
-  XFREE_CLEAR(replace_stack);
-  replace_stack_len = 0;
-  replace_stack_nr = 0;
+  int len = utf_head_off(&kv_A(replace_stack, 0),
+                         &kv_A(replace_stack, kv_size(replace_stack) - 1)) + 1;
+  kv_size(replace_stack) -= (size_t)len;
+  ins_bytes_len(&kv_A(replace_stack, kv_size(replace_stack)), (size_t)len);
 }
 
 // Handle doing a BS for one character.
@@ -2955,7 +2899,7 @@ static void replace_do_bs(int limit_col)
   colnr_T start_vcol;
   const int l_State = State;
 
-  int cc = replace_pop();
+  int cc = replace_pop_if_nul();
   if (cc > 0) {
     int orig_len = 0;
     int orig_vcols = 0;
@@ -2969,7 +2913,6 @@ static void replace_do_bs(int limit_col)
     if (l_State & VREPLACE_FLAG) {
       orig_len = get_cursor_pos_len();
     }
-    replace_push(cc);
     replace_pop_ins();
 
     if (l_State & VREPLACE_FLAG) {
@@ -3628,9 +3571,9 @@ static void ins_shift(int c, int lastc)
     if (lastc == '^') {
       old_indent = get_indent();        // remember curr. indent
     }
-    change_indent(INDENT_SET, 0, true, 0, true);
+    change_indent(INDENT_SET, 0, true, true);
   } else {
-    change_indent(c == Ctrl_D ? INDENT_DEC : INDENT_INC, 0, true, 0, true);
+    change_indent(c == Ctrl_D ? INDENT_DEC : INDENT_INC, 0, true, true);
   }
 
   if (did_ai && *skipwhite(get_cursor_line_ptr()) != NUL) {
@@ -3749,7 +3692,7 @@ static bool ins_bs(int c, int mode, int *inserted_space_p)
     // cc >= 0: NL was replaced, put original characters back
     cc = -1;
     if (State & REPLACE_FLAG) {
-      cc = replace_pop();           // returns -1 if NL was inserted
+      cc = replace_pop_if_nul();  // returns -1 if NL was inserted
     }
     // In replace mode, in the line we started replacing, we only move the
     // cursor.
@@ -3795,9 +3738,9 @@ static bool ins_bs(int c, int mode, int *inserted_space_p)
         // restore characters (blanks) deleted after cursor
         while (cc > 0) {
           colnr_T save_col = curwin->w_cursor.col;
-          mb_replace_pop_ins(cc);
+          mb_replace_pop_ins();
           curwin->w_cursor.col = save_col;
-          cc = replace_pop();
+          cc = replace_pop_if_nul();
         }
         // restore the characters that NL replaced
         replace_pop_ins();
@@ -3906,7 +3849,7 @@ static bool ins_bs(int c, int mode, int *inserted_space_p)
         } else {
           ins_str(" ");
           if ((State & REPLACE_FLAG)) {
-            replace_push(NUL);
+            replace_push_nul();
           }
         }
       }
@@ -4316,7 +4259,7 @@ static bool ins_tab(void)
     } else {
       ins_str(" ");
       if (State & REPLACE_FLAG) {            // no char replaced
-        replace_push(NUL);
+        replace_push_nul();
       }
     }
   }
@@ -4483,7 +4426,7 @@ bool ins_eol(int c)
   // character under the cursor.  Only push a NUL on the replace stack,
   // nothing to put back when the NL is deleted.
   if ((State & REPLACE_FLAG) && !(State & VREPLACE_FLAG)) {
-    replace_push(NUL);
+    replace_push_nul();
   }
 
   // In MODE_VREPLACE state, a NL replaces the rest of the line, and starts
@@ -4684,7 +4627,7 @@ static void ins_try_si(int c)
       i = get_indent();
       curwin->w_cursor = old_pos;
       if (State & VREPLACE_FLAG) {
-        change_indent(INDENT_SET, i, false, NUL, true);
+        change_indent(INDENT_SET, i, false, true);
       } else {
         set_indent(i, SIN_CHANGED);
       }

src/nvim/eval/funcs.c

@@ -7641,7 +7641,7 @@ static void get_xdg_var_list(const XDGVarType xdg, typval_T *rettv)
     return;
   }
   const void *iter = NULL;
-  const char *appname = get_appname();
+  const char *appname = get_appname(false);
   do {
     size_t dir_len;
     const char *dir;

src/nvim/ex_docmd.c

@@ -2500,15 +2500,13 @@ int parse_command_modifiers(exarg_T *eap, const char **errormsg, cmdmod_T *cmod,
     // ignore comment and empty lines
     if (*eap->cmd == '"') {
       // a comment ends at a NL
-      if (eap->nextcmd == NULL) {
-        eap->nextcmd = vim_strchr(eap->cmd, '\n');
-        if (eap->nextcmd != NULL) {
-          eap->nextcmd++;
-        }
+      eap->nextcmd = vim_strchr(eap->cmd, '\n');
+      if (eap->nextcmd != NULL) {
+        eap->nextcmd++;
       }
       return FAIL;
     }
-    if (eap->nextcmd == NULL && *eap->cmd == '\n') {
+    if (*eap->cmd == '\n') {
       eap->nextcmd = eap->cmd + 1;
       return FAIL;
     }

src/nvim/extmark.c

@@ -70,24 +70,19 @@ void extmark_set(buf_T *buf, uint32_t ns_id, uint32_t *idp, int row, colnr_T col
         extmark_del_id(buf, ns_id, id);
       } else {
         assert(marktree_itr_valid(itr));
-        bool invalid = mt_invalid(old_mark);
         if (old_mark.pos.row == row && old_mark.pos.col == col) {
           // not paired: we can revise in place
-          if (!invalid && mt_decor_any(old_mark)) {
-            // TODO(bfredl): conflict of concerns: buf_decor_remove() must process
-            // the buffer as if MT_FLAG_DECOR_SIGNTEXT is already removed, however
-            // marktree must precisely adjust the set of flags from the old set to the new
-            uint16_t save_flags = mt_itr_rawkey(itr).flags;
-            mt_itr_rawkey(itr).flags &= (uint16_t) ~MT_FLAG_DECOR_SIGNTEXT;
+          if (!mt_invalid(old_mark) && mt_decor_any(old_mark)) {
+            mt_itr_rawkey(itr).flags &= (uint16_t) ~MT_FLAG_EXTERNAL_MASK;
             buf_decor_remove(buf, row, row, col, mt_decor(old_mark), true);
-            mt_itr_rawkey(itr).flags = save_flags;
           }
-          marktree_revise_flags(buf->b_marktree, itr, flags);
+          mt_itr_rawkey(itr).flags |= flags;
           mt_itr_rawkey(itr).decor_data = decor.data;
+          marktree_revise_meta(buf->b_marktree, itr, old_mark);
           goto revised;
         }
         marktree_del_itr(buf->b_marktree, itr, false);
-        if (!invalid) {
+        if (!mt_invalid(old_mark)) {
           buf_decor_remove(buf, old_mark.pos.row, old_mark.pos.row, old_mark.pos.col,
                            mt_decor(old_mark), true);
         }
@@ -131,6 +126,7 @@ static void extmark_setraw(buf_T *buf, uint64_t mark, int row, colnr_T col, bool
   int row2 = 0;
   if (invalid) {
     mt_itr_rawkey(itr).flags &= (uint16_t) ~MT_FLAG_INVALID;
+    marktree_revise_meta(buf->b_marktree, itr, key);
   } else if (move && key.flags & MT_FLAG_DECOR_SIGNTEXT && buf->b_signcols.autom) {
     MTPos end = marktree_get_altpos(buf->b_marktree, key, NULL);
     row1 = MIN(end.row, MIN(key.pos.row, row));
@@ -394,6 +390,7 @@ void extmark_splice_delete(buf_T *buf, int l_row, colnr_T l_col, int u_row, coln
         } else {
           invalidated = true;
           mt_itr_rawkey(itr).flags |= MT_FLAG_INVALID;
+          marktree_revise_meta(buf->b_marktree, itr, mark);
           buf_decor_remove(buf, mark.pos.row, endpos.row, mark.pos.col, mt_decor(mark), false);
         }
       }

src/nvim/fileio.c

@@ -3264,18 +3264,12 @@ static void vim_mktempdir(void)
   char tmp[TEMP_FILE_PATH_MAXLEN];
   char path[TEMP_FILE_PATH_MAXLEN];
   char user[40] = { 0 };
-  char appname[40] = { 0 };
 
   os_get_username(user, sizeof(user));
   // Usernames may contain slashes! #19240
   memchrsub(user, '/', '_', sizeof(user));
   memchrsub(user, '\\', '_', sizeof(user));
 
-  // Appname may be a relative path, replace slashes to make it name-like.
-  xstrlcpy(appname, get_appname(), sizeof(appname));
-  memchrsub(appname, '/', '%', sizeof(appname));
-  memchrsub(appname, '\\', '%', sizeof(appname));
-
   // Make sure the umask doesn't remove the executable bit.
   // "repl" has been reported to use "0177".
   mode_t umask_save = umask(0077);
@@ -3283,14 +3277,15 @@ static void vim_mktempdir(void)
     // Expand environment variables, leave room for "/tmp/nvim.<user>/XXXXXX/999999999".
     expand_env((char *)temp_dirs[i], tmp, TEMP_FILE_PATH_MAXLEN - 64);
     if (!os_isdir(tmp)) {
+      if (strequal("$TMPDIR", temp_dirs[i])) {
+        WLOG("$TMPDIR tempdir not a directory (or does not exist): %s", tmp);
+      }
       continue;
     }
 
     // "/tmp/" exists, now try to create "/tmp/nvim.<user>/".
     add_pathsep(tmp);
-
-    xstrlcat(tmp, appname, sizeof(tmp));
-    xstrlcat(tmp, ".", sizeof(tmp));
+    xstrlcat(tmp, "nvim.", sizeof(tmp));
     xstrlcat(tmp, user, sizeof(tmp));
     os_mkdir(tmp, 0700);  // Always create, to avoid a race.
     bool owned = os_file_owned(tmp);

src/nvim/indent.c

@@ -891,7 +891,17 @@ int get_breakindent_win(win_T *wp, char *line)
           if (wp->w_briopt_list > 0) {
             prev_list += wp->w_briopt_list;
           } else {
-            prev_indent = (int)(*regmatch.endp - *regmatch.startp);
+            char *ptr = *regmatch.startp;
+            char *end_ptr = *regmatch.endp;
+            int indent = 0;
+            // Compute the width of the matched text.
+            // Use win_chartabsize() so that TAB size is correct,
+            // while wrapping is ignored.
+            while (ptr < end_ptr) {
+              indent += win_chartabsize(wp, ptr, indent);
+              MB_PTR_ADV(ptr);
+            }
+            prev_indent = indent;
           }
         }
         vim_regfree(regmatch.regprog);
@@ -1407,7 +1417,7 @@ void fixthisline(IndentGetter get_the_indent)
     return;
   }
 
-  change_indent(INDENT_SET, amount, false, 0, true);
+  change_indent(INDENT_SET, amount, false, true);
   if (linewhite(curwin->w_cursor.lnum)) {
     did_ai = true;  // delete the indent if the line stays empty
   }

src/nvim/main.c

@@ -266,7 +266,7 @@ int main(int argc, char **argv)
 
   if (argc > 1 && STRICMP(argv[1], "-ll") == 0) {
     if (argc == 2) {
-      print_mainerr(err_arg_missing, argv[1]);
+      print_mainerr(err_arg_missing, argv[1], NULL);
       exit(1);
     }
     nlua_run_script(argv, argc, 3);
@@ -357,10 +357,8 @@ int main(int argc, char **argv)
   assert(!ui_client_channel_id && !use_builtin_ui);
   // Nvim server...
 
-  int listen_rv = server_init(params.listen_addr);
-  if (listen_rv != 0) {
-    mainerr("Failed to --listen", listen_rv < 0
-            ? os_strerror(listen_rv) : (listen_rv == 1 ? "empty address" : NULL));
+  if (!server_init(params.listen_addr)) {
+    mainerr(IObuff, NULL, NULL);
   }
 
   TIME_MSG("expanding arguments");
@@ -1053,7 +1051,7 @@ static void command_line_scan(mparm_T *parmp)
     // "+" or "+{number}" or "+/{pat}" or "+{command}" argument.
     if (argv[0][0] == '+' && !had_minmin) {
       if (parmp->n_commands >= MAX_ARG_CMDS) {
-        mainerr(err_extra_cmd, NULL);
+        mainerr(err_extra_cmd, NULL, NULL);
       }
       argv_idx = -1;  // skip to next argument
       if (argv[0][1] == NUL) {
@@ -1074,7 +1072,7 @@ static void command_line_scan(mparm_T *parmp)
           parmp->no_swap_file = true;
         } else {
           if (parmp->edit_type > EDIT_STDIN) {
-            mainerr(err_too_many_args, argv[0]);
+            mainerr(err_too_many_args, argv[0], NULL);
           }
           parmp->had_stdin_file = true;
           parmp->edit_type = EDIT_STDIN;
@@ -1137,7 +1135,7 @@ static void command_line_scan(mparm_T *parmp)
           nlua_disable_preload = true;
         } else {
           if (argv[0][argv_idx]) {
-            mainerr(err_opt_unknown, argv[0]);
+            mainerr(err_opt_unknown, argv[0], NULL);
           }
           had_minmin = true;
         }
@@ -1211,7 +1209,7 @@ static void command_line_scan(mparm_T *parmp)
         break;
       case 'q':    // "-q" QuickFix mode
         if (parmp->edit_type != EDIT_NONE) {
-          mainerr(err_too_many_args, argv[0]);
+          mainerr(err_too_many_args, argv[0], NULL);
         }
         parmp->edit_type = EDIT_QF;
         if (argv[0][argv_idx]) {  // "-q{errorfile}"
@@ -1240,7 +1238,7 @@ static void command_line_scan(mparm_T *parmp)
         break;
       case 't':    // "-t {tag}" or "-t{tag}" jump to tag
         if (parmp->edit_type != EDIT_NONE) {
-          mainerr(err_too_many_args, argv[0]);
+          mainerr(err_too_many_args, argv[0], NULL);
         }
         parmp->edit_type = EDIT_TAG;
         if (argv[0][argv_idx]) {  // "-t{tag}"
@@ -1274,7 +1272,7 @@ static void command_line_scan(mparm_T *parmp)
       case 'c':    // "-c{command}" or "-c {command}" exec command
         if (argv[0][argv_idx] != NUL) {
           if (parmp->n_commands >= MAX_ARG_CMDS) {
-            mainerr(err_extra_cmd, NULL);
+            mainerr(err_extra_cmd, NULL, NULL);
           }
           parmp->commands[parmp->n_commands++] = argv[0] + argv_idx;
           argv_idx = -1;
@@ -1291,19 +1289,19 @@ static void command_line_scan(mparm_T *parmp)
         break;
 
       default:
-        mainerr(err_opt_unknown, argv[0]);
+        mainerr(err_opt_unknown, argv[0], NULL);
       }
 
       // Handle option arguments with argument.
       if (want_argument) {
         // Check for garbage immediately after the option letter.
         if (argv[0][argv_idx] != NUL) {
-          mainerr(err_opt_garbage, argv[0]);
+          mainerr(err_opt_garbage, argv[0], NULL);
         }
 
         argc--;
         if (argc < 1 && c != 'S') {  // -S has an optional argument
-          mainerr(err_arg_missing, argv[0]);
+          mainerr(err_arg_missing, argv[0], NULL);
         }
         argv++;
         argv_idx = -1;
@@ -1312,7 +1310,7 @@ static void command_line_scan(mparm_T *parmp)
         case 'c':    // "-c {command}" execute command
         case 'S':    // "-S {file}" execute Vim script
           if (parmp->n_commands >= MAX_ARG_CMDS) {
-            mainerr(err_extra_cmd, NULL);
+            mainerr(err_extra_cmd, NULL, NULL);
           }
           if (c == 'S') {
             char *a;
@@ -1343,7 +1341,7 @@ static void command_line_scan(mparm_T *parmp)
           if (strequal(argv[-1], "--cmd")) {
             // "--cmd {command}" execute command
             if (parmp->n_pre_commands >= MAX_ARG_CMDS) {
-              mainerr(err_extra_cmd, NULL);
+              mainerr(err_extra_cmd, NULL, NULL);
             }
             parmp->pre_commands[parmp->n_pre_commands++] = argv[0];
           } else if (strequal(argv[-1], "--listen")) {
@@ -1425,7 +1423,7 @@ scripterror:
 
       // Check for only one type of editing.
       if (parmp->edit_type > EDIT_STDIN) {
-        mainerr(err_too_many_args, argv[0]);
+        mainerr(err_too_many_args, argv[0], NULL);
       }
       parmp->edit_type = EDIT_FILE;
 
@@ -1472,7 +1470,7 @@ scripterror:
   }
 
   if (embedded_mode && (silent_mode || parmp->luaf)) {
-    mainerr(_("--embed conflicts with -es/-Es/-l"), NULL);
+    mainerr(_("--embed conflicts with -es/-Es/-l"), NULL, NULL);
   }
 
   // If there is a "+123" or "-c" command, set v:swapcommand to the first one.
@@ -2135,28 +2133,30 @@ static int execute_env(char *env)
   return OK;
 }
 
-/// Prints the following then exits:
-/// - An error message `errstr`
-/// - A string `str` if not null
+/// Prints a message of the form "{msg1}: {msg2}: {msg3}", then exits with code 1.
 ///
-/// @param errstr  string containing an error message
-/// @param str     string to append to the primary error message, or NULL
-static void mainerr(const char *errstr, const char *str)
+/// @param msg1  error message
+/// @param msg2  extra message, or NULL
+/// @param msg3  extra message, or NULL
+static void mainerr(const char *msg1, const char *msg2, const char *msg3)
   FUNC_ATTR_NORETURN
 {
-  print_mainerr(errstr, str);
+  print_mainerr(msg1, msg2, msg3);
   os_exit(1);
 }
 
-static void print_mainerr(const char *errstr, const char *str)
+static void print_mainerr(const char *msg1, const char *msg2, const char *msg3)
 {
   char *prgname = path_tail(argv0);
 
   signal_stop();              // kill us with CTRL-C here, if you like
 
-  fprintf(stderr, "%s: %s", prgname, _(errstr));
-  if (str != NULL) {
-    fprintf(stderr, ": \"%s\"", str);
+  fprintf(stderr, "%s: %s", prgname, _(msg1));
+  if (msg2 != NULL) {
+    fprintf(stderr, ": \"%s\"", msg2);
+  }
+  if (msg3 != NULL) {
+    fprintf(stderr, ": \"%s\"", msg3);
   }
   fprintf(stderr, _("\nMore info with \""));
   fprintf(stderr, "%s -h\"\n", prgname);

src/nvim/marktree.c

@@ -446,7 +446,7 @@ static MTNode *marktree_alloc_node(MarkTree *b, bool internal)
 // really meta_inc[kMTMetaCount]
 static void meta_describe_key_inc(uint32_t *meta_inc, MTKey *k)
 {
-  if (!mt_end(*k)) {
+  if (!mt_end(*k) && !mt_invalid(*k)) {
     meta_inc[kMTMetaInline] += (k->flags & MT_FLAG_DECOR_VIRT_TEXT_INLINE) ? 1 : 0;
     meta_inc[kMTMetaLines] += (k->flags & MT_FLAG_DECOR_VIRT_LINES) ? 1 : 0;
     meta_inc[kMTMetaSignHL] += (k->flags & MT_FLAG_DECOR_SIGNHL) ? 1 : 0;
@@ -774,14 +774,10 @@ uint64_t marktree_del_itr(MarkTree *b, MarkTreeIter *itr, bool rev)
   return other;
 }
 
-void marktree_revise_flags(MarkTree *b, MarkTreeIter *itr, uint16_t new_flags)
+void marktree_revise_meta(MarkTree *b, MarkTreeIter *itr, MTKey old_key)
 {
-  uint32_t meta_old[4];
-  meta_describe_key(meta_old, rawkey(itr));
-  rawkey(itr).flags &= (uint16_t) ~MT_FLAG_EXTERNAL_MASK;
-  rawkey(itr).flags |= new_flags;
-
-  uint32_t meta_new[4];
+  uint32_t meta_old[4], meta_new[4];
+  meta_describe_key(meta_old, old_key);
   meta_describe_key(meta_new, rawkey(itr));
 
   if (!memcmp(meta_old, meta_new, sizeof(meta_old))) {

src/nvim/mbyte.c

@@ -523,12 +523,14 @@ int utf_ptr2cells(const char *p_in)
 }
 
 /// Convert a UTF-8 byte sequence to a character number.
-/// Doesn't handle ascii! only multibyte and illegal sequences.
+/// Doesn't handle ascii! only multibyte and illegal sequences. ASCII (including NUL)
+/// are treated like illegal sequences.
 ///
 /// @param[in]  p      String to convert.
 /// @param[in]  len    Length of the character in bytes, 0 or 1 if illegal.
 ///
-/// @return Unicode codepoint. A negative value when the sequence is illegal.
+/// @return Unicode codepoint. A negative value when the sequence is illegal (or
+///         ASCII, including NUL).
 int32_t utf_ptr2CharInfo_impl(uint8_t const *p, uintptr_t const len)
   FUNC_ATTR_PURE FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
 {
@@ -1780,15 +1782,15 @@ int utf_head_off(const char *base_in, const char *p_in)
     start--;
   }
 
-  uint8_t cur_len = utf8len_tab[*start];
-  int32_t cur_code = utf_ptr2CharInfo_impl(start, (uintptr_t)cur_len);
-  if (cur_code < 0) {
+  const uint8_t last_len = utf8len_tab[*start];
+  int32_t cur_code = utf_ptr2CharInfo_impl(start, (uintptr_t)last_len);
+  if (cur_code < 0 || p - start >= last_len) {
     return 0;  // p must be part of an illegal sequence
   }
-  const uint8_t * const safe_end = start + cur_len;
+  const uint8_t * const safe_end = start + last_len;
 
   int cur_bc = utf8proc_get_property(cur_code)->boundclass;
-  if (always_break(cur_bc)) {
+  if (always_break(cur_bc) || start == base) {
     return (int)(p - start);
   }
 
@@ -1796,18 +1798,23 @@ int utf_head_off(const char *base_in, const char *p_in)
   const uint8_t *cur_pos = start;
   const uint8_t *const p_start = start;
 
-  if (start == base) {
-    return (int)(p - start);
-  }
+  while (true) {
+    if (start[-1] == NUL) {
+      break;
+    }
+
+    start--;
+    if (*start < 0x80) {  // stop on ascii, we are done
+      break;
+    }
 
-  start--;
-  while (*start >= 0x80) {  // stop on ascii, we are done
     while (start > base && (*start & 0xc0) == 0x80 && (cur_pos - start) < 6) {
       start--;
     }
 
-    int32_t prev_code = utf_ptr2CharInfo_impl(start, (uintptr_t)utf8len_tab[*start]);
-    if (prev_code < 0) {
+    int prev_len = utf8len_tab[*start];
+    int32_t prev_code = utf_ptr2CharInfo_impl(start, (uintptr_t)prev_len);
+    if (prev_code < 0 || prev_len < cur_pos - start) {
       start = cur_pos;  // start at valid sequence after invalid bytes
       break;
     }
@@ -1822,12 +1829,10 @@ int utf_head_off(const char *base_in, const char *p_in)
     cur_pos = start;
     cur_bc = prev_bc;
     cur_code = prev_code;
-
-    start--;
   }
 
   // hot path: we are already on the first codepoint of a sequence
-  if (start == p_start) {
+  if (start == p_start && last_len > p - start) {
     return (int)(p - start);
   }
 
@@ -2920,17 +2925,17 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     emsg(_(e_listreq));
     return;
   }
+
   const list_T *const l = argvars[0].vval.v_list;
-  if (tv_list_len(l) == 0) {
+  cw_interval_T *table = NULL;
+  const size_t table_size = (size_t)tv_list_len(l);
+  if (table_size == 0) {
     // Clearing the table.
-    xfree(cw_table);
-    cw_table = NULL;
-    cw_table_size = 0;
-    return;
+    goto update;
   }
 
   // Note: use list_T instead of listitem_T so that TV_LIST_ITEM_NEXT can be used properly below.
-  const list_T **ptrs = xmalloc(sizeof(const list_T *) * (size_t)tv_list_len(l));
+  const list_T **ptrs = xmalloc(sizeof(const list_T *) * table_size);
 
   // Check that all entries are a list with three numbers, the range is
   // valid and the cell width is valid.
@@ -2982,12 +2987,12 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   });
 
   // Sort the list on the first number.
-  qsort((void *)ptrs, (size_t)tv_list_len(l), sizeof(const list_T *), tv_nr_compare);
+  qsort((void *)ptrs, table_size, sizeof(const list_T *), tv_nr_compare);
 
-  cw_interval_T *table = xmalloc(sizeof(cw_interval_T) * (size_t)tv_list_len(l));
+  table = xmalloc(sizeof(cw_interval_T) * table_size);
 
   // Store the items in the new table.
-  for (item = 0; item < tv_list_len(l); item++) {
+  for (item = 0; (size_t)item < table_size; item++) {
     const list_T *const li_l = ptrs[item];
     const listitem_T *lili = tv_list_first(li_l);
     const varnumber_T n1 = TV_LIST_ITEM_TV(lili)->vval.v_number;
@@ -3006,10 +3011,12 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 
   xfree((void *)ptrs);
 
+update:
+  ;
   cw_interval_T *const cw_table_save = cw_table;
   const size_t cw_table_size_save = cw_table_size;
   cw_table = table;
-  cw_table_size = (size_t)tv_list_len(l);
+  cw_table_size = table_size;
 
   // Check that the new value does not conflict with 'listchars' or
   // 'fillchars'.

src/nvim/msgpack_rpc/server.c

@@ -11,12 +11,14 @@
 #include "nvim/event/socket.h"
 #include "nvim/garray.h"
 #include "nvim/garray_defs.h"
+#include "nvim/globals.h"
 #include "nvim/log.h"
 #include "nvim/main.h"
 #include "nvim/memory.h"
 #include "nvim/msgpack_rpc/server.h"
 #include "nvim/os/os.h"
 #include "nvim/os/stdpaths_defs.h"
+#include "nvim/types_defs.h"
 
 #define MAX_CONNECTIONS 32
 #define ENV_LISTEN "NVIM_LISTEN_ADDRESS"  // deprecated
@@ -27,36 +29,30 @@ static garray_T watchers = GA_EMPTY_INIT_VALUE;
 # include "msgpack_rpc/server.c.generated.h"
 #endif
 
-/// Initializes the module
+/// Initializes resources, handles `--listen`, starts the primary server at v:servername.
 ///
-/// @returns 0: success, 1: validation error, 2: already listening, -errno: failed to bind/listen.
-int server_init(const char *listen_addr)
+/// @returns true on success, false on fatal error (message stored in IObuff)
+bool server_init(const char *listen_addr)
 {
+  bool ok = true;
   bool must_free = false;
+  TriState user_arg = kTrue;  // User-provided --listen arg.
   ga_init(&watchers, sizeof(SocketWatcher *), 1);
 
   // $NVIM_LISTEN_ADDRESS (deprecated)
   if ((!listen_addr || listen_addr[0] == '\0') && os_env_exists(ENV_LISTEN)) {
+    user_arg = kFalse;  // User-provided env var.
     listen_addr = os_getenv(ENV_LISTEN);
   }
 
   if (!listen_addr || listen_addr[0] == '\0') {
+    user_arg = kNone;  // Autogenerated server address.
     listen_addr = server_address_new(NULL);
     must_free = true;
   }
 
-  if (!listen_addr) {
-    abort();  // Cannot happen.
-  }
-
   int rv = server_start(listen_addr);
 
-  if (os_env_exists(ENV_LISTEN)) {
-    // Unset $NVIM_LISTEN_ADDRESS, it's a liability hereafter. It is "input only", it must not be
-    // leaked to child jobs or :terminal.
-    os_unsetenv(ENV_LISTEN);
-  }
-
   // TODO(justinmk): this is for logging_spec. Can remove this after nvim_log #7062 is merged.
   if (os_env_exists("__NVIM_TEST_LOG")) {
     ELOG("test log message");
@@ -66,7 +62,28 @@ int server_init(const char *listen_addr)
     xfree((char *)listen_addr);
   }
 
-  return rv;
+  if (rv == 0 || user_arg == kNone) {
+    // The autogenerated servername can fail if the user has a broken $XDG_RUNTIME_DIR. #30282
+    // But that is not fatal (startup will continue, logged in $NVIM_LOGFILE, empty v:servername).
+    goto end;
+  }
+
+  (void)snprintf(IObuff, IOSIZE,
+                 user_arg ==
+                 kTrue ? "Failed to --listen: %s: \"%s\""
+                       : "Failed $NVIM_LISTEN_ADDRESS: %s: \"%s\"",
+                 rv < 0 ? os_strerror(rv) : (rv == 1 ? "empty address" : "?"),
+                 listen_addr);
+  ok = false;
+
+end:
+  if (os_env_exists(ENV_LISTEN)) {
+    // Unset $NVIM_LISTEN_ADDRESS, it's a liability hereafter. It is "input only", it must not be
+    // leaked to child jobs or :terminal.
+    os_unsetenv(ENV_LISTEN);
+  }
+
+  return ok;
 }
 
 /// Teardown a single server
@@ -97,17 +114,19 @@ void server_teardown(void)
 /// - Windows: "\\.\pipe\<name>.<pid>.<counter>"
 /// - Other: "/tmp/nvim.user/xxx/<name>.<pid>.<counter>"
 char *server_address_new(const char *name)
+  FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_RET
 {
   static uint32_t count = 0;
   char fmt[ADDRESS_MAX_SIZE];
-  const char *appname = get_appname();
 #ifdef MSWIN
+  (void)get_appname(true);
   int r = snprintf(fmt, sizeof(fmt), "\\\\.\\pipe\\%s.%" PRIu64 ".%" PRIu32,
-                   name ? name : appname, os_get_pid(), count++);
+                   name ? name : NameBuff, os_get_pid(), count++);
 #else
   char *dir = stdpaths_get_xdg_var(kXDGRuntimeDir);
+  (void)get_appname(true);
   int r = snprintf(fmt, sizeof(fmt), "%s/%s.%" PRIu64 ".%" PRIu32,
-                   dir, name ? name : appname, os_get_pid(), count++);
+                   dir, name ? name : NameBuff, os_get_pid(), count++);
   xfree(dir);
 #endif
   if ((size_t)r >= sizeof(fmt)) {

src/nvim/ops.c

@@ -306,7 +306,7 @@ void shift_line(bool left, bool round, int amount, int call_changed_bytes)
 
   // Set new indent
   if (State & VREPLACE_FLAG) {
-    change_indent(INDENT_SET, count, false, NUL, call_changed_bytes);
+    change_indent(INDENT_SET, count, false, call_changed_bytes);
   } else {
     set_indent(count, call_changed_bytes ? SIN_CHANGED : 0);
   }

src/nvim/options.lua

@@ -761,9 +761,9 @@ return {
         	list:{n}    Adds an additional indent for lines that match a
         		    numbered or bulleted list (using the
         		    'formatlistpat' setting).
-        	list:-1	    Uses the length of a match with 'formatlistpat'
-        		    for indentation.
         		    (default: 0)
+        	list:-1	    Uses the width of a match with 'formatlistpat' for
+        		    indentation.
         	column:{n}  Indent at column {n}. Will overrule the other
         		    sub-options. Note: an additional indent may be
         		    added for the 'showbreak' setting.

src/nvim/os/stdpaths.c

@@ -63,22 +63,32 @@ static const char *const xdg_defaults[] = {
 #endif
 };
 
-/// Get the value of $NVIM_APPNAME or "nvim" if not set.
+/// Gets the value of $NVIM_APPNAME, or "nvim" if not set.
+///
+/// @param namelike Write "name-like" value (no path separators) in `NameBuff`.
 ///
 /// @return $NVIM_APPNAME value
-const char *get_appname(void)
+const char *get_appname(bool namelike)
 {
   const char *env_val = os_getenv("NVIM_APPNAME");
   if (env_val == NULL || *env_val == NUL) {
     env_val = "nvim";
   }
+
+  if (namelike) {
+    // Appname may be a relative path, replace slashes to make it name-like.
+    xstrlcpy(NameBuff, env_val, sizeof(NameBuff));
+    memchrsub(NameBuff, '/', '-', sizeof(NameBuff));
+    memchrsub(NameBuff, '\\', '-', sizeof(NameBuff));
+  }
+
   return env_val;
 }
 
 /// Ensure that APPNAME is valid. Must be a name or relative path.
 bool appname_is_valid(void)
 {
-  const char *appname = get_appname();
+  const char *appname = get_appname(false);
   if (path_is_absolute(appname)
       // TODO(justinmk): on Windows, path_is_absolute says "/" is NOT absolute. Should it?
       || strequal(appname, "/")
@@ -193,7 +203,7 @@ char *get_xdg_home(const XDGVarType idx)
   FUNC_ATTR_WARN_UNUSED_RESULT
 {
   char *dir = stdpaths_get_xdg_var(idx);
-  const char *appname = get_appname();
+  const char *appname = get_appname(false);
   size_t appname_len = strlen(appname);
   assert(appname_len < (IOSIZE - sizeof("-data")));
 

src/nvim/runtime.c

@@ -1559,7 +1559,7 @@ static inline char *add_env_sep_dirs(char *dest, const char *const val, const ch
     return dest;
   }
   const void *iter = NULL;
-  const char *appname = get_appname();
+  const char *appname = get_appname(false);
   const size_t appname_len = strlen(appname);
   do {
     size_t dir_len;
@@ -1626,7 +1626,7 @@ static inline char *add_dir(char *dest, const char *const dir, const size_t dir_
     if (!after_pathsep(dest - 1, dest)) {
       *dest++ = PATHSEP;
     }
-    const char *appname = get_appname();
+    const char *appname = get_appname(false);
     size_t appname_len = strlen(appname);
     assert(appname_len < (IOSIZE - sizeof("-data")));
     xmemcpyz(IObuff, appname, appname_len);
@@ -1697,7 +1697,7 @@ char *runtimepath_default(bool clean_arg)
   size_t config_len = 0;
   size_t vimruntime_len = 0;
   size_t libdir_len = 0;
-  const char *appname = get_appname();
+  const char *appname = get_appname(false);
   size_t appname_len = strlen(appname);
   if (data_home != NULL) {
     data_len = strlen(data_home);

src/nvim/textformat.c

@@ -400,7 +400,7 @@ void internal_format(int textwidth, int second_indent, int flags, bool format_on
         }
         if (second_indent >= 0) {
           if (State & VREPLACE_FLAG) {
-            change_indent(INDENT_SET, second_indent, false, NUL, true);
+            change_indent(INDENT_SET, second_indent, false, true);
           } else if (leader_len > 0 && second_indent - leader_len > 0) {
             int padding = second_indent - leader_len;
 

test/functional/api/vim_spec.lua

@@ -3201,7 +3201,7 @@ describe('API', function()
   end)
 
   describe('nvim_get_runtime_file', function()
-    local p = n.alter_slashes
+    local p = t.fix_slashes
     it('can find files', function()
       eq({}, api.nvim_get_runtime_file('bork.borkbork', false))
       eq({}, api.nvim_get_runtime_file('bork.borkbork', true))
@@ -3210,36 +3210,36 @@ describe('API', function()
       local val = api.nvim_get_runtime_file('autoload/remote/*.vim', true)
       eq(2, #val)
       if endswith(val[1], 'define.vim') then
-        ok(endswith(val[1], p 'autoload/remote/define.vim'))
-        ok(endswith(val[2], p 'autoload/remote/host.vim'))
+        ok(endswith(p(val[1]), 'autoload/remote/define.vim'))
+        ok(endswith(p(val[2]), 'autoload/remote/host.vim'))
       else
-        ok(endswith(val[1], p 'autoload/remote/host.vim'))
-        ok(endswith(val[2], p 'autoload/remote/define.vim'))
+        ok(endswith(p(val[1]), 'autoload/remote/host.vim'))
+        ok(endswith(p(val[2]), 'autoload/remote/define.vim'))
       end
       val = api.nvim_get_runtime_file('autoload/remote/*.vim', false)
       eq(1, #val)
       ok(
-        endswith(val[1], p 'autoload/remote/define.vim')
-          or endswith(val[1], p 'autoload/remote/host.vim')
+        endswith(p(val[1]), 'autoload/remote/define.vim')
+          or endswith(p(val[1]), 'autoload/remote/host.vim')
       )
 
       val = api.nvim_get_runtime_file('lua', true)
       eq(1, #val)
-      ok(endswith(val[1], p 'lua'))
+      ok(endswith(p(val[1]), 'lua'))
 
       val = api.nvim_get_runtime_file('lua/vim', true)
       eq(1, #val)
-      ok(endswith(val[1], p 'lua/vim'))
+      ok(endswith(p(val[1]), 'lua/vim'))
     end)
 
     it('can find directories', function()
       local val = api.nvim_get_runtime_file('lua/', true)
       eq(1, #val)
-      ok(endswith(val[1], p 'lua/'))
+      ok(endswith(p(val[1]), 'lua/'))
 
       val = api.nvim_get_runtime_file('lua/vim/', true)
       eq(1, #val)
-      ok(endswith(val[1], p 'lua/vim/'))
+      ok(endswith(p(val[1]), 'lua/vim/'))
 
       eq({}, api.nvim_get_runtime_file('foobarlang/', true))
     end)

test/functional/autocmd/dirchanged_spec.lua

@@ -9,7 +9,7 @@ local request = n.request
 local is_os = t.is_os
 
 describe('autocmd DirChanged and DirChangedPre', function()
-  local curdir = vim.uv.cwd():gsub('\\', '/')
+  local curdir = t.fix_slashes(vim.uv.cwd())
   local dirs = {
     curdir .. '/Xtest-functional-autocmd-dirchanged.dir1',
     curdir .. '/Xtest-functional-autocmd-dirchanged.dir2',

test/functional/core/fileio_spec.lua

@@ -321,11 +321,11 @@ end)
 describe('tmpdir', function()
   local tmproot_pat = [=[.*[/\\]nvim%.[^/\\]+]=]
   local testlog = 'Xtest_tmpdir_log'
-  local os_tmpdir
+  local os_tmpdir ---@type string
 
   before_each(function()
     -- Fake /tmp dir so that we can mess it up.
-    os_tmpdir = vim.uv.fs_mkdtemp(vim.fs.dirname(t.tmpname(false)) .. '/nvim_XXXXXXXXXX')
+    os_tmpdir = assert(vim.uv.fs_mkdtemp(vim.fs.dirname(t.tmpname(false)) .. '/nvim_XXXXXXXXXX'))
   end)
 
   after_each(function()
@@ -414,15 +414,4 @@ describe('tmpdir', function()
     rm_tmpdir()
     eq('E5431: tempdir disappeared (3 times)', api.nvim_get_vvar('errmsg'))
   end)
-
-  it('$NVIM_APPNAME relative path', function()
-    clear({
-      env = {
-        NVIM_APPNAME = 'a/b',
-        NVIM_LOG_FILE = testlog,
-        TMPDIR = os_tmpdir,
-      },
-    })
-    matches([=[.*[/\\]a%%b%.[^/\\]+]=], fn.tempname())
-  end)
 end)

test/functional/core/server_spec.lua

@@ -41,6 +41,21 @@ describe('server', function()
     end
   end)
 
+  it('broken $XDG_RUNTIME_DIR is not fatal #30282', function()
+    clear {
+      args_rm = { '--listen' },
+      env = { NVIM_LOG_FILE = testlog, XDG_RUNTIME_DIR = '/non-existent-dir/subdir//' },
+    }
+
+    if is_os('win') then
+      -- Windows pipes have a special namespace and thus aren't decided by $XDG_RUNTIME_DIR.
+      matches('nvim', api.nvim_get_vvar('servername'))
+    else
+      eq('', api.nvim_get_vvar('servername'))
+      t.assert_log('Failed to start server%: no such file or directory', testlog, 100)
+    end
+  end)
+
   it('serverstart(), serverstop() does not set $NVIM', function()
     clear()
     local s = eval('serverstart()')
@@ -139,7 +154,7 @@ describe('server', function()
     clear_serverlist()
 
     -- Address without slashes is a "name" which is appended to a generated path. #8519
-    matches([[.*[/\\]xtest1%.2%.3%.4[^/\\]*]], fn.serverstart('xtest1.2.3.4'))
+    matches([[[/\\]xtest1%.2%.3%.4[^/\\]*]], fn.serverstart('xtest1.2.3.4'))
     clear_serverlist()
 
     eq('Vim:Failed to start server: invalid argument', pcall_err(fn.serverstart, '127.0.0.1:65536')) -- invalid port
@@ -175,56 +190,79 @@ describe('server', function()
 end)
 
 describe('startup --listen', function()
+  -- Tests Nvim output when failing to start, with and without "--headless".
+  -- TODO(justinmk): clear() should have a way to get stdout if Nvim fails to start.
+  local function _test(args, env, expected)
+    local function run(cmd)
+      return n.exec_lua(function(cmd_, env_)
+        return vim
+          .system(cmd_, {
+            text = true,
+            env = vim.tbl_extend(
+              'force',
+              -- Avoid noise in the logs; we expect failures for these tests.
+              { NVIM_LOG_FILE = testlog },
+              env_ or {}
+            ),
+          })
+          :wait()
+      end, cmd, env) --[[@as vim.SystemCompleted]]
+    end
+
+    local cmd = vim.list_extend({ n.nvim_prog, '+qall!', '--headless' }, args)
+    local r = run(cmd)
+    eq(1, r.code)
+    matches(expected, (r.stderr .. r.stdout):gsub('\\n', ' '))
+
+    if is_os('win') then
+      return -- On Windows, output without --headless is garbage.
+    end
+    table.remove(cmd, 3) -- Remove '--headless'.
+    assert(not vim.tbl_contains(cmd, '--headless'))
+    r = run(cmd)
+    eq(1, r.code)
+    matches(expected, (r.stderr .. r.stdout):gsub('\\n', ' '))
+  end
+
   it('validates', function()
     clear { env = { NVIM_LOG_FILE = testlog } }
-
-    -- Tests args with and without "--headless".
-    local function _test(args, expected)
-      local function run(cmd)
-        return n.exec_lua(function(cmd_)
-          return vim
-            .system(cmd_, {
-              text = true,
-              env = {
-                -- Avoid noise in the logs; we expect failures for these tests.
-                NVIM_LOG_FILE = testlog,
-              },
-            })
-            :wait()
-        end, cmd) --[[@as vim.SystemCompleted]]
-      end
-
-      local cmd = vim.list_extend({ n.nvim_prog, '+qall!', '--headless' }, args)
-      local r = run(cmd)
-      eq(1, r.code)
-      matches(expected, (r.stderr .. r.stdout):gsub('\\n', ' '))
-
-      if is_os('win') then
-        return -- On Windows, output without --headless is garbage.
-      end
-      table.remove(cmd, 3) -- Remove '--headless'.
-      assert(not vim.tbl_contains(cmd, '--headless'))
-      r = run(cmd)
-      eq(1, r.code)
-      matches(expected, (r.stderr .. r.stdout):gsub('\\n', ' '))
-    end
+    local in_use = n.eval('v:servername') ---@type string Address already used by another server.
 
     t.assert_nolog('Failed to start server', testlog, 100)
     t.assert_nolog('Host lookup failed', testlog, 100)
 
-    _test({ '--listen' }, 'nvim.*: Argument missing after: "%-%-listen"')
-    _test({ '--listen2' }, 'nvim.*: Garbage after option argument: "%-%-listen2"')
-    _test({ '--listen', n.eval('v:servername') }, 'nvim.*: Failed to %-%-listen: ".* already .*"')
-    _test({ '--listen', '/' }, 'nvim.*: Failed to %-%-listen: ".*"')
+    _test({ '--listen' }, nil, 'nvim.*: Argument missing after: "%-%-listen"')
+    _test({ '--listen2' }, nil, 'nvim.*: Garbage after option argument: "%-%-listen2"')
+    _test(
+      { '--listen', in_use },
+      nil,
+      ('nvim.*: Failed to %%-%%-listen: [^:]+ already [^:]+: "%s"'):format(vim.pesc(in_use))
+    )
+    _test({ '--listen', '/' }, nil, 'nvim.*: Failed to %-%-listen: [^:]+: "/"')
     _test(
       { '--listen', 'https://example.com' },
-      ('nvim.*: Failed to %%-%%-listen: "%s"'):format(
+      nil,
+      ('nvim.*: Failed to %%-%%-listen: %s: "https://example.com"'):format(
         is_os('mac') and 'unknown node or service' or 'service not available for socket type'
       )
     )
 
     t.assert_log('Failed to start server', testlog, 100)
     t.assert_log('Host lookup failed', testlog, 100)
+
+    _test(
+      {},
+      { NVIM_LISTEN_ADDRESS = in_use },
+      ('nvim.*: Failed $NVIM_LISTEN_ADDRESS: [^:]+ already [^:]+: "%s"'):format(vim.pesc(in_use))
+    )
+    _test({}, { NVIM_LISTEN_ADDRESS = '/' }, 'nvim.*: Failed $NVIM_LISTEN_ADDRESS: [^:]+: "/"')
+    _test(
+      {},
+      { NVIM_LISTEN_ADDRESS = 'https://example.com' },
+      ('nvim.*: Failed $NVIM_LISTEN_ADDRESS: %s: "https://example.com"'):format(
+        is_os('mac') and 'unknown node or service' or 'service not available for socket type'
+      )
+    )
   end)
 
   it('sets v:servername, overrides $NVIM_LISTEN_ADDRESS', function()
@@ -235,6 +273,6 @@ describe('startup --listen', function()
 
     -- Address without slashes is a "name" which is appended to a generated path. #8519
     clear({ args = { '--listen', 'test-name' } })
-    matches([[.*[/\\]test%-name[^/\\]*]], api.nvim_get_vvar('servername'))
+    matches([[[/\\]test%-name[^/\\]*]], api.nvim_get_vvar('servername'))
   end)
 end)

test/functional/core/startup_spec.lua

@@ -27,7 +27,6 @@ local sleep = vim.uv.sleep
 local startswith = vim.startswith
 local write_file = t.write_file
 local api = n.api
-local alter_slashes = n.alter_slashes
 local is_os = t.is_os
 local dedent = t.dedent
 local tbl_map = vim.tbl_map
@@ -40,22 +39,15 @@ local testlog = 'Xtest-startupspec-log'
 describe('startup', function()
   it('--clean', function()
     clear()
-    ok(
-      string.find(
-        alter_slashes(api.nvim_get_option_value('runtimepath', {})),
-        fn.stdpath('config'),
-        1,
-        true
-      ) ~= nil
+    matches(
+      vim.pesc(t.fix_slashes(fn.stdpath('config'))),
+      t.fix_slashes(api.nvim_get_option_value('runtimepath', {}))
     )
+
     clear('--clean')
     ok(
-      string.find(
-        alter_slashes(api.nvim_get_option_value('runtimepath', {})),
-        fn.stdpath('config'),
-        1,
-        true
-      ) == nil
+      not t.fix_slashes(api.nvim_get_option_value('runtimepath', {}))
+        :match(vim.pesc(t.fix_slashes(fn.stdpath('config'))))
     )
   end)
 

test/functional/editor/mode_insert_spec.lua

@@ -351,4 +351,97 @@ describe('insert-mode', function()
       eq(2, api.nvim_win_get_cursor(0)[1])
     end)
   end)
+
+  it('backspace after replacing multibyte chars', function()
+    local screen = Screen.new(30, 3)
+    screen:attach()
+    api.nvim_buf_set_lines(0, 0, -1, true, { 'test ȧ̟̜̝̅̚m̆̉̐̐̇̈ å' })
+    feed('^Rabcdefghi')
+    screen:expect([[
+      abcdefghi^                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<bs>')
+    screen:expect([[
+      abcdefgh^å                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<bs>')
+    screen:expect([[
+      abcdefg^ å                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<bs>')
+    screen:expect([[
+      abcdef^m̆̉̐̐̇̈ å                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<bs>')
+    screen:expect([[
+      abcde^ȧ̟̜̝̅̚m̆̉̐̐̇̈ å                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<bs>')
+    screen:expect([[
+      abcd^ ȧ̟̜̝̅̚m̆̉̐̐̇̈ å                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<esc>')
+
+    api.nvim_buf_set_lines(0, 0, -1, true, { 'wow 🧑‍🌾🏳️‍⚧️x' })
+    feed('^Rabcd')
+
+    screen:expect([[
+      abcd^🧑‍🌾🏳️‍⚧️x                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('e')
+    screen:expect([[
+      abcde^🏳️‍⚧️x                      |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('f')
+    screen:expect([[
+      abcdef^x                       |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<bs>')
+    screen:expect([[
+      abcde^🏳️‍⚧️x                      |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<bs>')
+    screen:expect([[
+      abcd^🧑‍🌾🏳️‍⚧️x                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+
+    feed('<bs>')
+    screen:expect([[
+      abc^ 🧑‍🌾🏳️‍⚧️x                     |
+      {1:~                             }|
+      {5:-- REPLACE --}                 |
+    ]])
+  end)
 end)

test/functional/ex_cmds/mksession_spec.lua

@@ -170,7 +170,7 @@ describe(':mksession', function()
     skip(is_os('win'), 'causes rmdir() to fail')
 
     local cwd_dir = fn.fnamemodify('.', ':p:~'):gsub([[[\/]*$]], '')
-    cwd_dir = cwd_dir:gsub([[\]], '/') -- :mksession always uses unix slashes.
+    cwd_dir = t.fix_slashes(cwd_dir) -- :mksession always uses unix slashes.
     local session_path = cwd_dir .. '/' .. session_file
 
     command('cd ' .. tab_dir)

test/functional/lua/uri_spec.lua

@@ -217,7 +217,7 @@ describe('URI methods', function()
         ]],
         file
       )
-      local expected_uri = 'file:///' .. file:gsub('\\', '/')
+      local expected_uri = 'file:///' .. t.fix_slashes(file)
       eq(expected_uri, exec_lua(test_case))
       os.remove(file)
     end)

test/functional/lua/vim_spec.lua

@@ -1071,42 +1071,28 @@ describe('lua stdlib', function()
     ]])
     )
 
-    -- Fix github issue #23654
     ok(exec_lua([[
-      local a = { sub = { [1] = 'a' } }
-      local b = { sub = { b = 'a' } }
+      local a = { sub = { 'a', 'b' } }
+      local b = { sub = { 'b', 'c' } }
       local c = vim.tbl_deep_extend('force', a, b)
-      return vim.deep_equal(c, { sub = { [1] = 'a', b = 'a' } })
+      return vim.deep_equal(c, { sub = { 'b', 'c' } })
     ]]))
 
-    matches(
-      'invalid "behavior": nil',
-      pcall_err(
-        exec_lua,
-        [[
-        return vim.tbl_deep_extend()
-      ]]
-      )
-    )
+    matches('invalid "behavior": nil', pcall_err(exec_lua, [[return vim.tbl_deep_extend()]]))
 
     matches(
       'wrong number of arguments %(given 1, expected at least 3%)',
-      pcall_err(
-        exec_lua,
-        [[
-        return vim.tbl_deep_extend("keep")
-      ]]
-      )
+      pcall_err(exec_lua, [[return vim.tbl_deep_extend("keep")]])
     )
 
     matches(
       'wrong number of arguments %(given 2, expected at least 3%)',
-      pcall_err(
-        exec_lua,
-        [[
-        return vim.tbl_deep_extend("keep", {})
-      ]]
-      )
+      pcall_err(exec_lua, [[return vim.tbl_deep_extend("keep", {})]])
+    )
+
+    matches(
+      'after the second argument%: expected table, got number',
+      pcall_err(exec_lua, [[return vim.tbl_deep_extend("keep", {}, 42)]])
     )
   end)
 

test/functional/options/autochdir_spec.lua

@@ -22,7 +22,7 @@ describe("'autochdir'", function()
   end)
 
   it('is not overwritten by getwinvar() call #17609', function()
-    local curdir = vim.uv.cwd():gsub('\\', '/')
+    local curdir = t.fix_slashes(vim.uv.cwd())
     local dir_a = curdir .. '/Xtest-functional-options-autochdir.dir_a'
     local dir_b = curdir .. '/Xtest-functional-options-autochdir.dir_b'
     mkdir(dir_a)

test/functional/options/defaults_spec.lua

@@ -23,7 +23,6 @@ local insert = n.insert
 local neq = t.neq
 local mkdir = t.mkdir
 local rmdir = n.rmdir
-local alter_slashes = n.alter_slashes
 local tbl_contains = vim.tbl_contains
 local expect_exit = n.expect_exit
 local check_close = n.check_close
@@ -262,7 +261,7 @@ describe('startup defaults', function()
           NVIM_LOG_FILE = '', -- Empty is invalid.
         },
       })
-      eq(xdgstatedir .. '/log', string.gsub(eval('$NVIM_LOG_FILE'), '\\', '/'))
+      eq(xdgstatedir .. '/log', t.fix_slashes(eval('$NVIM_LOG_FILE')))
     end)
 
     it('defaults to stdpath("log")/log if invalid', function()
@@ -273,7 +272,7 @@ describe('startup defaults', function()
           NVIM_LOG_FILE = '.', -- Any directory is invalid.
         },
       })
-      eq(xdgstatedir .. '/log', string.gsub(eval('$NVIM_LOG_FILE'), '\\', '/'))
+      eq(xdgstatedir .. '/log', t.fix_slashes(eval('$NVIM_LOG_FILE')))
       -- Avoid "failed to open $NVIM_LOG_FILE" noise in test output.
       expect_exit(command, 'qall!')
     end)
@@ -383,69 +382,69 @@ describe('XDG defaults', function()
 
       eq(
         (
-          (
+          t.fix_slashes(
             root_path
-            .. ('/x'):rep(4096)
-            .. '/nvim'
-            .. ','
-            .. root_path
-            .. ('/a'):rep(2048)
-            .. '/nvim'
-            .. ','
-            .. root_path
-            .. ('/b'):rep(2048)
-            .. '/nvim'
-            .. (',' .. root_path .. '/c/nvim')
-            .. ','
-            .. root_path
-            .. ('/X'):rep(4096)
-            .. '/'
-            .. data_dir
-            .. '/site'
-            .. ','
-            .. root_path
-            .. ('/A'):rep(2048)
-            .. '/nvim/site'
-            .. ','
-            .. root_path
-            .. ('/B'):rep(2048)
-            .. '/nvim/site'
-            .. (',' .. root_path .. '/C/nvim/site')
-            .. ','
-            .. vimruntime
-            .. ','
-            .. libdir
-            .. (',' .. root_path .. '/C/nvim/site/after')
-            .. ','
-            .. root_path
-            .. ('/B'):rep(2048)
-            .. '/nvim/site/after'
-            .. ','
-            .. root_path
-            .. ('/A'):rep(2048)
-            .. '/nvim/site/after'
-            .. ','
-            .. root_path
-            .. ('/X'):rep(4096)
-            .. '/'
-            .. data_dir
-            .. '/site/after'
-            .. (',' .. root_path .. '/c/nvim/after')
-            .. ','
-            .. root_path
-            .. ('/b'):rep(2048)
-            .. '/nvim/after'
-            .. ','
-            .. root_path
-            .. ('/a'):rep(2048)
-            .. '/nvim/after'
-            .. ','
-            .. root_path
-            .. ('/x'):rep(4096)
-            .. '/nvim/after'
-          ):gsub('\\', '/')
+              .. ('/x'):rep(4096)
+              .. '/nvim'
+              .. ','
+              .. root_path
+              .. ('/a'):rep(2048)
+              .. '/nvim'
+              .. ','
+              .. root_path
+              .. ('/b'):rep(2048)
+              .. '/nvim'
+              .. (',' .. root_path .. '/c/nvim')
+              .. ','
+              .. root_path
+              .. ('/X'):rep(4096)
+              .. '/'
+              .. data_dir
+              .. '/site'
+              .. ','
+              .. root_path
+              .. ('/A'):rep(2048)
+              .. '/nvim/site'
+              .. ','
+              .. root_path
+              .. ('/B'):rep(2048)
+              .. '/nvim/site'
+              .. (',' .. root_path .. '/C/nvim/site')
+              .. ','
+              .. vimruntime
+              .. ','
+              .. libdir
+              .. (',' .. root_path .. '/C/nvim/site/after')
+              .. ','
+              .. root_path
+              .. ('/B'):rep(2048)
+              .. '/nvim/site/after'
+              .. ','
+              .. root_path
+              .. ('/A'):rep(2048)
+              .. '/nvim/site/after'
+              .. ','
+              .. root_path
+              .. ('/X'):rep(4096)
+              .. '/'
+              .. data_dir
+              .. '/site/after'
+              .. (',' .. root_path .. '/c/nvim/after')
+              .. ','
+              .. root_path
+              .. ('/b'):rep(2048)
+              .. '/nvim/after'
+              .. ','
+              .. root_path
+              .. ('/a'):rep(2048)
+              .. '/nvim/after'
+              .. ','
+              .. root_path
+              .. ('/x'):rep(4096)
+              .. '/nvim/after'
+          )
         ),
-        (api.nvim_get_option_value('runtimepath', {})):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('runtimepath', {}))
       )
       command('set runtimepath&')
       command('set backupdir&')
@@ -454,85 +453,85 @@ describe('XDG defaults', function()
       command('set viewdir&')
       eq(
         (
-          (
+          t.fix_slashes(
             root_path
-            .. ('/x'):rep(4096)
-            .. '/nvim'
-            .. ','
-            .. root_path
-            .. ('/a'):rep(2048)
-            .. '/nvim'
-            .. ','
-            .. root_path
-            .. ('/b'):rep(2048)
-            .. '/nvim'
-            .. (',' .. root_path .. '/c/nvim')
-            .. ','
-            .. root_path
-            .. ('/X'):rep(4096)
-            .. '/'
-            .. data_dir
-            .. '/site'
-            .. ','
-            .. root_path
-            .. ('/A'):rep(2048)
-            .. '/nvim/site'
-            .. ','
-            .. root_path
-            .. ('/B'):rep(2048)
-            .. '/nvim/site'
-            .. (',' .. root_path .. '/C/nvim/site')
-            .. ','
-            .. vimruntime
-            .. ','
-            .. libdir
-            .. (',' .. root_path .. '/C/nvim/site/after')
-            .. ','
-            .. root_path
-            .. ('/B'):rep(2048)
-            .. '/nvim/site/after'
-            .. ','
-            .. root_path
-            .. ('/A'):rep(2048)
-            .. '/nvim/site/after'
-            .. ','
-            .. root_path
-            .. ('/X'):rep(4096)
-            .. '/'
-            .. data_dir
-            .. '/site/after'
-            .. (',' .. root_path .. '/c/nvim/after')
-            .. ','
-            .. root_path
-            .. ('/b'):rep(2048)
-            .. '/nvim/after'
-            .. ','
-            .. root_path
-            .. ('/a'):rep(2048)
-            .. '/nvim/after'
-            .. ','
-            .. root_path
-            .. ('/x'):rep(4096)
-            .. '/nvim/after'
-          ):gsub('\\', '/')
+              .. ('/x'):rep(4096)
+              .. '/nvim'
+              .. ','
+              .. root_path
+              .. ('/a'):rep(2048)
+              .. '/nvim'
+              .. ','
+              .. root_path
+              .. ('/b'):rep(2048)
+              .. '/nvim'
+              .. (',' .. root_path .. '/c/nvim')
+              .. ','
+              .. root_path
+              .. ('/X'):rep(4096)
+              .. '/'
+              .. data_dir
+              .. '/site'
+              .. ','
+              .. root_path
+              .. ('/A'):rep(2048)
+              .. '/nvim/site'
+              .. ','
+              .. root_path
+              .. ('/B'):rep(2048)
+              .. '/nvim/site'
+              .. (',' .. root_path .. '/C/nvim/site')
+              .. ','
+              .. vimruntime
+              .. ','
+              .. libdir
+              .. (',' .. root_path .. '/C/nvim/site/after')
+              .. ','
+              .. root_path
+              .. ('/B'):rep(2048)
+              .. '/nvim/site/after'
+              .. ','
+              .. root_path
+              .. ('/A'):rep(2048)
+              .. '/nvim/site/after'
+              .. ','
+              .. root_path
+              .. ('/X'):rep(4096)
+              .. '/'
+              .. data_dir
+              .. '/site/after'
+              .. (',' .. root_path .. '/c/nvim/after')
+              .. ','
+              .. root_path
+              .. ('/b'):rep(2048)
+              .. '/nvim/after'
+              .. ','
+              .. root_path
+              .. ('/a'):rep(2048)
+              .. '/nvim/after'
+              .. ','
+              .. root_path
+              .. ('/x'):rep(4096)
+              .. '/nvim/after'
+          )
         ),
-        (api.nvim_get_option_value('runtimepath', {})):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('runtimepath', {}))
       )
       eq(
         '.,' .. root_path .. ('/X'):rep(4096) .. '/' .. state_dir .. '/backup//',
-        (api.nvim_get_option_value('backupdir', {}):gsub('\\', '/'))
+        t.fix_slashes(api.nvim_get_option_value('backupdir', {}))
       )
       eq(
         root_path .. ('/X'):rep(4096) .. '/' .. state_dir .. '/swap//',
-        (api.nvim_get_option_value('directory', {})):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('directory', {}))
       )
       eq(
         root_path .. ('/X'):rep(4096) .. '/' .. state_dir .. '/undo//',
-        (api.nvim_get_option_value('undodir', {})):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('undodir', {}))
       )
       eq(
         root_path .. ('/X'):rep(4096) .. '/' .. state_dir .. '/view//',
-        (api.nvim_get_option_value('viewdir', {})):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('viewdir', {}))
       )
     end)
   end)
@@ -574,26 +573,26 @@ describe('XDG defaults', function()
       local vimruntime, libdir = vimruntime_and_libdir()
       eq(
         (
-          (
+          t.fix_slashes(
             '$XDG_DATA_HOME/nvim'
-            .. ',$XDG_DATA_DIRS/nvim'
-            .. ',$XDG_CONFIG_HOME/'
-            .. data_dir
-            .. '/site'
-            .. ',$XDG_CONFIG_DIRS/nvim/site'
-            .. ','
-            .. vimruntime
-            .. ','
-            .. libdir
-            .. ',$XDG_CONFIG_DIRS/nvim/site/after'
-            .. ',$XDG_CONFIG_HOME/'
-            .. data_dir
-            .. '/site/after'
-            .. ',$XDG_DATA_DIRS/nvim/after'
-            .. ',$XDG_DATA_HOME/nvim/after'
-          ):gsub('\\', '/')
+              .. ',$XDG_DATA_DIRS/nvim'
+              .. ',$XDG_CONFIG_HOME/'
+              .. data_dir
+              .. '/site'
+              .. ',$XDG_CONFIG_DIRS/nvim/site'
+              .. ','
+              .. vimruntime
+              .. ','
+              .. libdir
+              .. ',$XDG_CONFIG_DIRS/nvim/site/after'
+              .. ',$XDG_CONFIG_HOME/'
+              .. data_dir
+              .. '/site/after'
+              .. ',$XDG_DATA_DIRS/nvim/after'
+              .. ',$XDG_DATA_HOME/nvim/after'
+          )
         ),
-        (api.nvim_get_option_value('runtimepath', {})):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('runtimepath', {}))
       )
       command('set runtimepath&')
       command('set backupdir&')
@@ -602,8 +601,47 @@ describe('XDG defaults', function()
       command('set viewdir&')
       eq(
         (
-          (
+          t.fix_slashes(
             '$XDG_DATA_HOME/nvim'
+              .. ',$XDG_DATA_DIRS/nvim'
+              .. ',$XDG_CONFIG_HOME/'
+              .. data_dir
+              .. '/site'
+              .. ',$XDG_CONFIG_DIRS/nvim/site'
+              .. ','
+              .. vimruntime
+              .. ','
+              .. libdir
+              .. ',$XDG_CONFIG_DIRS/nvim/site/after'
+              .. ',$XDG_CONFIG_HOME/'
+              .. data_dir
+              .. '/site/after'
+              .. ',$XDG_DATA_DIRS/nvim/after'
+              .. ',$XDG_DATA_HOME/nvim/after'
+          )
+        ),
+        t.fix_slashes(api.nvim_get_option_value('runtimepath', {}))
+      )
+      eq(
+        ('.,$XDG_CONFIG_HOME/' .. state_dir .. '/backup//'),
+        t.fix_slashes(api.nvim_get_option_value('backupdir', {}))
+      )
+      eq(
+        ('$XDG_CONFIG_HOME/' .. state_dir .. '/swap//'),
+        t.fix_slashes(api.nvim_get_option_value('directory', {}))
+      )
+      eq(
+        ('$XDG_CONFIG_HOME/' .. state_dir .. '/undo//'),
+        t.fix_slashes(api.nvim_get_option_value('undodir', {}))
+      )
+      eq(
+        ('$XDG_CONFIG_HOME/' .. state_dir .. '/view//'),
+        t.fix_slashes(api.nvim_get_option_value('viewdir', {}))
+      )
+      command('set all&')
+      eq(
+        t.fix_slashes(
+          '$XDG_DATA_HOME/nvim'
             .. ',$XDG_DATA_DIRS/nvim'
             .. ',$XDG_CONFIG_HOME/'
             .. data_dir
@@ -619,63 +657,24 @@ describe('XDG defaults', function()
             .. '/site/after'
             .. ',$XDG_DATA_DIRS/nvim/after'
             .. ',$XDG_DATA_HOME/nvim/after'
-          ):gsub('\\', '/')
         ),
-        (api.nvim_get_option_value('runtimepath', {})):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('runtimepath', {}))
       )
       eq(
         ('.,$XDG_CONFIG_HOME/' .. state_dir .. '/backup//'),
-        api.nvim_get_option_value('backupdir', {}):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('backupdir', {}))
       )
       eq(
         ('$XDG_CONFIG_HOME/' .. state_dir .. '/swap//'),
-        api.nvim_get_option_value('directory', {}):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('directory', {}))
       )
       eq(
         ('$XDG_CONFIG_HOME/' .. state_dir .. '/undo//'),
-        api.nvim_get_option_value('undodir', {}):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('undodir', {}))
       )
       eq(
         ('$XDG_CONFIG_HOME/' .. state_dir .. '/view//'),
-        api.nvim_get_option_value('viewdir', {}):gsub('\\', '/')
-      )
-      command('set all&')
-      eq(
-        (
-          '$XDG_DATA_HOME/nvim'
-          .. ',$XDG_DATA_DIRS/nvim'
-          .. ',$XDG_CONFIG_HOME/'
-          .. data_dir
-          .. '/site'
-          .. ',$XDG_CONFIG_DIRS/nvim/site'
-          .. ','
-          .. vimruntime
-          .. ','
-          .. libdir
-          .. ',$XDG_CONFIG_DIRS/nvim/site/after'
-          .. ',$XDG_CONFIG_HOME/'
-          .. data_dir
-          .. '/site/after'
-          .. ',$XDG_DATA_DIRS/nvim/after'
-          .. ',$XDG_DATA_HOME/nvim/after'
-        ):gsub('\\', '/'),
-        (api.nvim_get_option_value('runtimepath', {})):gsub('\\', '/')
-      )
-      eq(
-        ('.,$XDG_CONFIG_HOME/' .. state_dir .. '/backup//'),
-        api.nvim_get_option_value('backupdir', {}):gsub('\\', '/')
-      )
-      eq(
-        ('$XDG_CONFIG_HOME/' .. state_dir .. '/swap//'),
-        api.nvim_get_option_value('directory', {}):gsub('\\', '/')
-      )
-      eq(
-        ('$XDG_CONFIG_HOME/' .. state_dir .. '/undo//'),
-        api.nvim_get_option_value('undodir', {}):gsub('\\', '/')
-      )
-      eq(
-        ('$XDG_CONFIG_HOME/' .. state_dir .. '/view//'),
-        api.nvim_get_option_value('viewdir', {}):gsub('\\', '/')
+        t.fix_slashes(api.nvim_get_option_value('viewdir', {}))
       )
       eq(nil, (fn.tempname()):match('XDG_RUNTIME_DIR'))
     end)
@@ -915,7 +914,7 @@ describe('stdpath()', function()
     assert_alive() -- Check for crash. #8393
   end)
 
-  it('supports $NVIM_APPNAME', function()
+  it('$NVIM_APPNAME', function()
     local appname = 'NVIM_APPNAME_TEST' .. ('_'):rep(106)
     clear({ env = { NVIM_APPNAME = appname, NVIM_LOG_FILE = testlog } })
     eq(appname, fn.fnamemodify(fn.stdpath('config'), ':t'))
@@ -939,7 +938,7 @@ describe('stdpath()', function()
         local child = vim.fn.jobstart({ vim.v.progpath, '--clean', '--headless', '--listen', 'x', '+qall!' }, { env = { NVIM_APPNAME = %q } })
         return vim.fn.jobwait({ child }, %d)[1]
       ]],
-        alter_slashes(testAppname),
+        testAppname,
         3000
       )
       eq(expected_exitcode, exec_lua(lua_code))
@@ -957,24 +956,43 @@ describe('stdpath()', function()
     test_appname('a/b\\c', 0)
   end)
 
+  it('$NVIM_APPNAME relative path', function()
+    local tmpdir = t.tmpname(false)
+    t.mkdir(tmpdir)
+
+    clear({
+      args_rm = { '--listen' },
+      env = {
+        NVIM_APPNAME = 'relative/appname',
+        NVIM_LOG_FILE = testlog,
+        TMPDIR = tmpdir,
+      },
+    })
+
+    t.matches(vim.pesc(tmpdir), t.fix_slashes(fn.tempname()))
+    t.assert_nolog('tempdir', testlog, 100)
+    t.assert_nolog('TMPDIR', testlog, 100)
+    t.matches([=[[/\\]relative%-appname.[^/\\]+]=], api.nvim_get_vvar('servername'))
+  end)
+
   describe('returns a String', function()
     describe('with "config"', function()
       it('knows XDG_CONFIG_HOME', function()
         clear({
           env = {
-            XDG_CONFIG_HOME = alter_slashes('/home/docwhat/.config'),
+            XDG_CONFIG_HOME = '/home/docwhat/.config',
           },
         })
-        eq(alter_slashes('/home/docwhat/.config/nvim'), fn.stdpath('config'))
+        eq('/home/docwhat/.config/nvim', t.fix_slashes(fn.stdpath('config')))
       end)
 
       it('handles changes during runtime', function()
         clear({ env = {
-          XDG_CONFIG_HOME = alter_slashes('/home/original'),
+          XDG_CONFIG_HOME = '/home/original',
         } })
-        eq(alter_slashes('/home/original/nvim'), fn.stdpath('config'))
-        command("let $XDG_CONFIG_HOME='" .. alter_slashes('/home/new') .. "'")
-        eq(alter_slashes('/home/new/nvim'), fn.stdpath('config'))
+        eq('/home/original/nvim', t.fix_slashes(fn.stdpath('config')))
+        command("let $XDG_CONFIG_HOME='/home/new'")
+        eq('/home/new/nvim', t.fix_slashes(fn.stdpath('config')))
       end)
 
       it("doesn't expand $VARIABLES", function()
@@ -984,32 +1002,32 @@ describe('stdpath()', function()
             VARIABLES = 'this-should-not-happen',
           },
         })
-        eq(alter_slashes('$VARIABLES/nvim'), fn.stdpath('config'))
+        eq('$VARIABLES/nvim', t.fix_slashes(fn.stdpath('config')))
       end)
 
       it("doesn't expand ~/", function()
         clear({ env = {
-          XDG_CONFIG_HOME = alter_slashes('~/frobnitz'),
+          XDG_CONFIG_HOME = '~/frobnitz',
         } })
-        eq(alter_slashes('~/frobnitz/nvim'), fn.stdpath('config'))
+        eq('~/frobnitz/nvim', t.fix_slashes(fn.stdpath('config')))
       end)
     end)
 
     describe('with "data"', function()
       it('knows XDG_DATA_HOME', function()
         clear({ env = {
-          XDG_DATA_HOME = alter_slashes('/home/docwhat/.local'),
+          XDG_DATA_HOME = '/home/docwhat/.local',
         } })
-        eq(alter_slashes('/home/docwhat/.local/' .. datadir), fn.stdpath('data'))
+        eq('/home/docwhat/.local/' .. datadir, t.fix_slashes(fn.stdpath('data')))
       end)
 
       it('handles changes during runtime', function()
         clear({ env = {
-          XDG_DATA_HOME = alter_slashes('/home/original'),
+          XDG_DATA_HOME = '/home/original',
         } })
-        eq(alter_slashes('/home/original/' .. datadir), fn.stdpath('data'))
-        command("let $XDG_DATA_HOME='" .. alter_slashes('/home/new') .. "'")
-        eq(alter_slashes('/home/new/' .. datadir), fn.stdpath('data'))
+        eq('/home/original/' .. datadir, t.fix_slashes(fn.stdpath('data')))
+        command("let $XDG_DATA_HOME='/home/new'")
+        eq('/home/new/' .. datadir, t.fix_slashes(fn.stdpath('data')))
       end)
 
       it("doesn't expand $VARIABLES", function()
@@ -1019,14 +1037,14 @@ describe('stdpath()', function()
             VARIABLES = 'this-should-not-happen',
           },
         })
-        eq(alter_slashes('$VARIABLES/' .. datadir), fn.stdpath('data'))
+        eq('$VARIABLES/' .. datadir, t.fix_slashes(fn.stdpath('data')))
       end)
 
       it("doesn't expand ~/", function()
         clear({ env = {
-          XDG_DATA_HOME = alter_slashes('~/frobnitz'),
+          XDG_DATA_HOME = '~/frobnitz',
         } })
-        eq(alter_slashes('~/frobnitz/' .. datadir), fn.stdpath('data'))
+        eq('~/frobnitz/' .. datadir, t.fix_slashes(fn.stdpath('data')))
       end)
     end)
 
@@ -1034,19 +1052,19 @@ describe('stdpath()', function()
       it('knows XDG_STATE_HOME', function()
         clear({
           env = {
-            XDG_STATE_HOME = alter_slashes('/home/docwhat/.local'),
+            XDG_STATE_HOME = '/home/docwhat/.local',
           },
         })
-        eq(alter_slashes('/home/docwhat/.local/' .. statedir), fn.stdpath('state'))
+        eq('/home/docwhat/.local/' .. statedir, t.fix_slashes(fn.stdpath('state')))
       end)
 
       it('handles changes during runtime', function()
         clear({ env = {
-          XDG_STATE_HOME = alter_slashes('/home/original'),
+          XDG_STATE_HOME = '/home/original',
         } })
-        eq(alter_slashes('/home/original/' .. statedir), fn.stdpath('state'))
-        command("let $XDG_STATE_HOME='" .. alter_slashes('/home/new') .. "'")
-        eq(alter_slashes('/home/new/' .. statedir), fn.stdpath('state'))
+        eq('/home/original/' .. statedir, t.fix_slashes(fn.stdpath('state')))
+        command("let $XDG_STATE_HOME='" .. '/home/new' .. "'")
+        eq('/home/new/' .. statedir, t.fix_slashes(fn.stdpath('state')))
       end)
 
       it("doesn't expand $VARIABLES", function()
@@ -1056,14 +1074,14 @@ describe('stdpath()', function()
             VARIABLES = 'this-should-not-happen',
           },
         })
-        eq(alter_slashes('$VARIABLES/' .. statedir), fn.stdpath('state'))
+        eq('$VARIABLES/' .. statedir, t.fix_slashes(fn.stdpath('state')))
       end)
 
       it("doesn't expand ~/", function()
         clear({ env = {
-          XDG_STATE_HOME = alter_slashes('~/frobnitz'),
+          XDG_STATE_HOME = '~/frobnitz',
         } })
-        eq(alter_slashes('~/frobnitz/' .. statedir), fn.stdpath('state'))
+        eq('~/frobnitz/' .. statedir, t.fix_slashes(fn.stdpath('state')))
       end)
     end)
 
@@ -1071,19 +1089,19 @@ describe('stdpath()', function()
       it('knows XDG_CACHE_HOME', function()
         clear({
           env = {
-            XDG_CACHE_HOME = alter_slashes('/home/docwhat/.cache'),
+            XDG_CACHE_HOME = '/home/docwhat/.cache',
           },
         })
-        eq(alter_slashes('/home/docwhat/.cache/nvim'), fn.stdpath('cache'))
+        eq('/home/docwhat/.cache/nvim', t.fix_slashes(fn.stdpath('cache')))
       end)
 
       it('handles changes during runtime', function()
         clear({ env = {
-          XDG_CACHE_HOME = alter_slashes('/home/original'),
+          XDG_CACHE_HOME = '/home/original',
         } })
-        eq(alter_slashes('/home/original/nvim'), fn.stdpath('cache'))
-        command("let $XDG_CACHE_HOME='" .. alter_slashes('/home/new') .. "'")
-        eq(alter_slashes('/home/new/nvim'), fn.stdpath('cache'))
+        eq('/home/original/nvim', t.fix_slashes(fn.stdpath('cache')))
+        command("let $XDG_CACHE_HOME='" .. '/home/new' .. "'")
+        eq('/home/new/nvim', t.fix_slashes(fn.stdpath('cache')))
       end)
 
       it("doesn't expand $VARIABLES", function()
@@ -1093,14 +1111,14 @@ describe('stdpath()', function()
             VARIABLES = 'this-should-not-happen',
           },
         })
-        eq(alter_slashes('$VARIABLES/nvim'), fn.stdpath('cache'))
+        eq('$VARIABLES/nvim', t.fix_slashes(fn.stdpath('cache')))
       end)
 
       it("doesn't expand ~/", function()
         clear({ env = {
-          XDG_CACHE_HOME = alter_slashes('~/frobnitz'),
+          XDG_CACHE_HOME = '~/frobnitz',
         } })
-        eq(alter_slashes('~/frobnitz/nvim'), fn.stdpath('cache'))
+        eq('~/frobnitz/nvim', t.fix_slashes(fn.stdpath('cache')))
       end)
     end)
   end)
@@ -1114,6 +1132,7 @@ describe('stdpath()', function()
           HOMEDRIVE = 'C:',
           HOMEPATH = '\\Users\\docwhat',
           LOCALAPPDATA = 'C:\\Users\\docwhat\\AppData\\Local',
+          NVIM_LOG_FILE = testlog,
           TEMP = 'C:\\Users\\docwhat\\AppData\\Local\\Temp',
           TMPDIR = 'C:\\Users\\docwhat\\AppData\\Local\\Temp',
           TMP = 'C:\\Users\\docwhat\\AppData\\Local\\Temp',
@@ -1124,6 +1143,7 @@ describe('stdpath()', function()
           HOMEDRIVE = 'HOMEDRIVE-should-be-ignored',
           HOMEPATH = 'HOMEPATH-should-be-ignored',
           LOCALAPPDATA = 'LOCALAPPDATA-should-be-ignored',
+          NVIM_LOG_FILE = testlog,
           TEMP = 'TEMP-should-be-ignored',
           TMPDIR = 'TMPDIR-should-be-ignored',
           TMP = 'TMP-should-be-ignored',
@@ -1147,12 +1167,18 @@ describe('stdpath()', function()
       describe(msg, function()
         it('set via system', function()
           set_paths_via_system(env_var_name, paths)
-          eq(expected_paths, fn.stdpath(stdpath_arg))
+          eq(expected_paths, t.fix_slashes(fn.stdpath(stdpath_arg)))
+          if not is_os('win') then
+            assert_log('$TMPDIR tempdir not a directory.*TMPDIR%-should%-be%-ignored', testlog, 100)
+          end
         end)
 
         it('set at runtime', function()
           set_paths_at_runtime(env_var_name, paths)
-          eq(expected_paths, fn.stdpath(stdpath_arg))
+          eq(expected_paths, t.fix_slashes(fn.stdpath(stdpath_arg)))
+          if not is_os('win') then
+            assert_log('$TMPDIR tempdir not a directory.*TMPDIR%-should%-be%-ignored', testlog, 100)
+          end
         end)
       end)
     end
@@ -1163,10 +1189,10 @@ describe('stdpath()', function()
         'config_dirs',
         'XDG_CONFIG_DIRS',
         {
-          alter_slashes('/home/docwhat/.config'),
+          t.fix_slashes('/home/docwhat/.config'),
         },
         {
-          alter_slashes('/home/docwhat/.config/nvim'),
+          t.fix_slashes('/home/docwhat/.config/nvim'),
         }
       )
 
@@ -1175,12 +1201,12 @@ describe('stdpath()', function()
         'config_dirs',
         'XDG_CONFIG_DIRS',
         {
-          alter_slashes('/home/docwhat/.config'),
-          alter_slashes('/etc/config'),
+          t.fix_slashes('/home/docwhat/.config'),
+          t.fix_slashes('/etc/config'),
         },
         {
-          alter_slashes('/home/docwhat/.config/nvim'),
-          alter_slashes('/etc/config/nvim'),
+          t.fix_slashes('/home/docwhat/.config/nvim'),
+          t.fix_slashes('/etc/config/nvim'),
         }
       )
 
@@ -1190,25 +1216,25 @@ describe('stdpath()', function()
         'XDG_CONFIG_DIRS',
         { '$HOME', '$TMP' },
         {
-          alter_slashes('$HOME/nvim'),
-          alter_slashes('$TMP/nvim'),
+          t.fix_slashes('$HOME/nvim'),
+          t.fix_slashes('$TMP/nvim'),
         }
       )
 
       behaves_like_dir_list_env("doesn't expand ~/", 'config_dirs', 'XDG_CONFIG_DIRS', {
-        alter_slashes('~/.oldconfig'),
-        alter_slashes('~/.olderconfig'),
+        t.fix_slashes('~/.oldconfig'),
+        t.fix_slashes('~/.olderconfig'),
       }, {
-        alter_slashes('~/.oldconfig/nvim'),
-        alter_slashes('~/.olderconfig/nvim'),
+        t.fix_slashes('~/.oldconfig/nvim'),
+        t.fix_slashes('~/.olderconfig/nvim'),
       })
     end)
 
     describe('with "data_dirs"', function()
       behaves_like_dir_list_env('knows XDG_DATA_DIRS with one path', 'data_dirs', 'XDG_DATA_DIRS', {
-        alter_slashes('/home/docwhat/.data'),
+        t.fix_slashes('/home/docwhat/.data'),
       }, {
-        alter_slashes('/home/docwhat/.data/nvim'),
+        t.fix_slashes('/home/docwhat/.data/nvim'),
       })
 
       behaves_like_dir_list_env(
@@ -1216,12 +1242,12 @@ describe('stdpath()', function()
         'data_dirs',
         'XDG_DATA_DIRS',
         {
-          alter_slashes('/home/docwhat/.data'),
-          alter_slashes('/etc/local'),
+          t.fix_slashes('/home/docwhat/.data'),
+          t.fix_slashes('/etc/local'),
         },
         {
-          alter_slashes('/home/docwhat/.data/nvim'),
-          alter_slashes('/etc/local/nvim'),
+          t.fix_slashes('/home/docwhat/.data/nvim'),
+          t.fix_slashes('/etc/local/nvim'),
         }
       )
 
@@ -1231,17 +1257,17 @@ describe('stdpath()', function()
         'XDG_DATA_DIRS',
         { '$HOME', '$TMP' },
         {
-          alter_slashes('$HOME/nvim'),
-          alter_slashes('$TMP/nvim'),
+          t.fix_slashes('$HOME/nvim'),
+          t.fix_slashes('$TMP/nvim'),
         }
       )
 
       behaves_like_dir_list_env("doesn't expand ~/", 'data_dirs', 'XDG_DATA_DIRS', {
-        alter_slashes('~/.oldconfig'),
-        alter_slashes('~/.olderconfig'),
+        t.fix_slashes('~/.oldconfig'),
+        t.fix_slashes('~/.olderconfig'),
       }, {
-        alter_slashes('~/.oldconfig/nvim'),
-        alter_slashes('~/.olderconfig/nvim'),
+        t.fix_slashes('~/.oldconfig/nvim'),
+        t.fix_slashes('~/.olderconfig/nvim'),
       })
     end)
   end)

test/functional/plugin/lsp_spec.lua

@@ -3607,21 +3607,21 @@ describe('LSP', function()
             range = {
               ['end'] = {
                 character = 8,
-                line = 9,
+                line = 3,
               },
               start = {
                 character = 6,
-                line = 9,
+                line = 3,
               },
             },
             selectionRange = {
               ['end'] = {
                 character = 8,
-                line = 9,
+                line = 3,
               },
               start = {
                 character = 6,
-                line = 9,
+                line = 3,
               },
             },
             uri = 'file:///home/jiangyinzuo/hello.cpp',
@@ -3651,21 +3651,21 @@ describe('LSP', function()
             range = {
               ['end'] = {
                 character = 8,
-                line = 8,
+                line = 2,
               },
               start = {
                 character = 6,
-                line = 8,
+                line = 2,
               },
             },
             selectionRange = {
               ['end'] = {
                 character = 8,
-                line = 8,
+                line = 2,
               },
               start = {
                 character = 6,
-                line = 8,
+                line = 2,
               },
             },
             uri = 'file:///home/jiangyinzuo/hello.cpp',
@@ -3679,7 +3679,15 @@ describe('LSP', function()
         })
         local client_id = vim.lsp.start({ name = 'dummy', cmd = server.cmd })
         local handler = require 'vim.lsp.handlers'['typeHierarchy/subtypes']
-        handler(nil, clangd_response, { client_id = client_id, bufnr = 1 })
+        local bufnr = vim.api.nvim_get_current_buf()
+        vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, {
+          'class B : public A{};',
+          'class C : public B{};',
+          'class D1 : public C{};',
+          'class D2 : public C{};',
+          'class E : public D1, D2 {};',
+        })
+        handler(nil, clangd_response, { client_id = client_id, bufnr = bufnr })
         return vim.fn.getqflist()
       end)
 
@@ -3689,7 +3697,7 @@ describe('LSP', function()
           col = 7,
           end_col = 0,
           end_lnum = 0,
-          lnum = 10,
+          lnum = 4,
           module = '',
           nr = 0,
           pattern = '',
@@ -3703,7 +3711,7 @@ describe('LSP', function()
           col = 7,
           end_col = 0,
           end_lnum = 0,
-          lnum = 9,
+          lnum = 3,
           module = '',
           nr = 0,
           pattern = '',
@@ -3763,7 +3771,15 @@ describe('LSP', function()
         })
         local client_id = vim.lsp.start({ name = 'dummy', cmd = server.cmd })
         local handler = require 'vim.lsp.handlers'['typeHierarchy/subtypes']
-        handler(nil, jdtls_response, { client_id = client_id, bufnr = 1 })
+        local bufnr = vim.api.nvim_get_current_buf()
+        vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, {
+          'package mylist;',
+          '',
+          'public class MyList {',
+          ' static class Inner extends MyList{}',
+          '~}',
+        })
+        handler(nil, jdtls_response, { client_id = client_id, bufnr = bufnr })
         return vim.fn.getqflist()
       end)
 
@@ -3840,21 +3856,21 @@ describe('LSP', function()
             range = {
               ['end'] = {
                 character = 8,
-                line = 9,
+                line = 3,
               },
               start = {
                 character = 6,
-                line = 9,
+                line = 3,
               },
             },
             selectionRange = {
               ['end'] = {
                 character = 8,
-                line = 9,
+                line = 3,
               },
               start = {
                 character = 6,
-                line = 9,
+                line = 3,
               },
             },
             uri = 'file:///home/jiangyinzuo/hello.cpp',
@@ -3884,21 +3900,21 @@ describe('LSP', function()
             range = {
               ['end'] = {
                 character = 8,
-                line = 8,
+                line = 2,
               },
               start = {
                 character = 6,
-                line = 8,
+                line = 2,
               },
             },
             selectionRange = {
               ['end'] = {
                 character = 8,
-                line = 8,
+                line = 2,
               },
               start = {
                 character = 6,
-                line = 8,
+                line = 2,
               },
             },
             uri = 'file:///home/jiangyinzuo/hello.cpp',
@@ -3912,7 +3928,16 @@ describe('LSP', function()
         })
         local client_id = vim.lsp.start({ name = 'dummy', cmd = server.cmd })
         local handler = require 'vim.lsp.handlers'['typeHierarchy/supertypes']
-        handler(nil, clangd_response, { client_id = client_id, bufnr = 1 })
+        local bufnr = vim.api.nvim_get_current_buf()
+        vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, {
+          'class B : public A{};',
+          'class C : public B{};',
+          'class D1 : public C{};',
+          'class D2 : public C{};',
+          'class E : public D1, D2 {};',
+        })
+
+        handler(nil, clangd_response, { client_id = client_id, bufnr = bufnr })
         return vim.fn.getqflist()
       end)
 
@@ -3922,7 +3947,7 @@ describe('LSP', function()
           col = 7,
           end_col = 0,
           end_lnum = 0,
-          lnum = 10,
+          lnum = 4,
           module = '',
           nr = 0,
           pattern = '',
@@ -3936,7 +3961,7 @@ describe('LSP', function()
           col = 7,
           end_col = 0,
           end_lnum = 0,
-          lnum = 9,
+          lnum = 3,
           module = '',
           nr = 0,
           pattern = '',
@@ -3996,7 +4021,15 @@ describe('LSP', function()
         })
         local client_id = vim.lsp.start({ name = 'dummy', cmd = server.cmd })
         local handler = require 'vim.lsp.handlers'['typeHierarchy/supertypes']
-        handler(nil, jdtls_response, { client_id = client_id, bufnr = 1 })
+        local bufnr = vim.api.nvim_get_current_buf()
+        vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, {
+          'package mylist;',
+          '',
+          'public class MyList {',
+          ' static class Inner extends MyList{}',
+          '~}',
+        })
+        handler(nil, jdtls_response, { client_id = client_id, bufnr = bufnr })
         return vim.fn.getqflist()
       end)
 

test/functional/plugin/tohtml_spec.lua

@@ -136,6 +136,50 @@ local function run_tohtml_and_assert(screen, func)
   screen:expect({ grid = expected.grid, attr_ids = expected.attr_ids })
 end
 
+---@param guifont boolean
+local function test_generates_html(guifont, expect_font)
+  insert([[line]])
+  exec('set termguicolors')
+  local bg = fn.synIDattr(fn.hlID('Normal'), 'bg#', 'gui')
+  local fg = fn.synIDattr(fn.hlID('Normal'), 'fg#', 'gui')
+  local tmpfile = t.tmpname()
+
+  exec_lua(
+    [[
+    local guifont, outfile = ...
+    local html = (guifont
+      and require('tohtml').tohtml(0,{title="title"})
+      or require('tohtml').tohtml(0,{title="title",font={ "dumyfont","anotherfont" }}))
+    vim.fn.writefile(html, outfile)
+    vim.cmd.split(outfile)
+  ]],
+    guifont,
+    tmpfile
+  )
+
+  local out_file = api.nvim_buf_get_name(api.nvim_get_current_buf())
+  eq({
+    '<!DOCTYPE html>',
+    '<html>',
+    '<head>',
+    '<meta charset="UTF-8">',
+    '<title>title</title>',
+    ('<meta name="colorscheme" content="%s"></meta>'):format(api.nvim_get_var('colors_name')),
+    '<style>',
+    ('* {font-family: %s,monospace}'):format(expect_font),
+    ('body {background-color: %s; color: %s}'):format(bg, fg),
+    '</style>',
+    '</head>',
+    '<body style="display: flex">',
+    '<pre>',
+    'line',
+    '',
+    '</pre>',
+    '</body>',
+    '</html>',
+  }, fn.readfile(out_file))
+end
+
 describe(':TOhtml', function()
   --- @type test.functional.ui.screen
   local screen
@@ -146,41 +190,16 @@ describe(':TOhtml', function()
     exec('colorscheme default')
   end)
 
-  it('expected internal html generated', function()
-    insert([[line]])
-    exec('set termguicolors')
-    local bg = fn.synIDattr(fn.hlID('Normal'), 'bg#', 'gui')
-    local fg = fn.synIDattr(fn.hlID('Normal'), 'fg#', 'gui')
-    exec_lua [[
-    local outfile = vim.fn.tempname() .. '.html'
-    local html = require('tohtml').tohtml(0,{title="title",font="dumyfont"})
-    vim.fn.writefile(html, outfile)
-    vim.cmd.split(outfile)
-    ]]
-    local out_file = api.nvim_buf_get_name(api.nvim_get_current_buf())
-    eq({
-      '<!DOCTYPE html>',
-      '<html>',
-      '<head>',
-      '<meta charset="UTF-8">',
-      '<title>title</title>',
-      ('<meta name="colorscheme" content="%s"></meta>'):format(api.nvim_get_var('colors_name')),
-      '<style>',
-      '* {font-family: dumyfont,monospace}',
-      ('body {background-color: %s; color: %s}'):format(bg, fg),
-      '</style>',
-      '</head>',
-      '<body style="display: flex">',
-      '<pre>',
-      'line',
-      '',
-      '</pre>',
-      '</body>',
-      '</html>',
-    }, fn.readfile(out_file))
+  it('generates html with given font', function()
+    test_generates_html(false, '"dumyfont","anotherfont"')
   end)
 
-  it('expected internal html generated from range', function()
+  it("generates html, respects 'guifont'", function()
+    exec_lua [[vim.o.guifont='Font,Escape\\,comma, Ignore space after comma']]
+    test_generates_html(true, '"Font","Escape,comma","Ignore space after comma"')
+  end)
+
+  it('generates html from range', function()
     insert([[
     line1
     line2
@@ -218,7 +237,7 @@ describe(':TOhtml', function()
     }, fn.readfile(out_file))
   end)
 
-  it('highlight attributes generated', function()
+  it('generates highlight attributes', function()
     --Make sure to uncomment the attribute in `html_syntax_match()`
     exec('hi LINE guisp=#00ff00 gui=' .. table.concat({
       'bold',

test/functional/terminal/buffer_spec.lua

@@ -342,7 +342,7 @@ describe(':terminal buffer', function()
     command('wincmd p')
 
     -- cwd will be inserted in a file URI, which cannot contain backs
-    local cwd = fn.getcwd():gsub('\\', '/')
+    local cwd = t.fix_slashes(fn.getcwd())
     local parent = cwd:match('^(.+/)')
     local expected = '\027]7;file://host' .. parent
     api.nvim_chan_send(term, string.format('%s\027\\', expected))

test/functional/testnvim.lua

@@ -14,8 +14,7 @@ local is_os = t.is_os
 local ok = t.ok
 local sleep = uv.sleep
 
---- This module uses functions from the context of the test session, i.e. in the context of the
---- nvim being tests.
+--- Functions executing in the current nvim session/process being tested.
 local M = {}
 
 local runtime_set = 'set runtimepath^=./build/lib/nvim/'
@@ -903,26 +902,6 @@ function M.missing_provider(provider)
   assert(false, 'Unknown provider: ' .. provider)
 end
 
---- @param obj string|table
---- @return any
-function M.alter_slashes(obj)
-  if not is_os('win') then
-    return obj
-  end
-  if type(obj) == 'string' then
-    local ret = obj:gsub('/', '\\')
-    return ret
-  elseif type(obj) == 'table' then
-    --- @cast obj table<any,any>
-    local ret = {} --- @type table<any,any>
-    for k, v in pairs(obj) do
-      ret[k] = M.alter_slashes(v)
-    end
-    return ret
-  end
-  assert(false, 'expected string or table of strings, got ' .. type(obj))
-end
-
 local load_factor = 1
 if t.is_ci() then
   -- Compute load factor only once (but outside of any tests).

test/functional/ui/decorations_spec.lua

@@ -5641,6 +5641,19 @@ l5
     ]])
     eq("Invalid 'sign_text'", pcall_err(api.nvim_buf_set_extmark, 0, ns, 5, 0, {sign_text='❤️x'}))
   end)
+
+  it('auto signcolumn hides with invalidated sign', function()
+    api.nvim_set_option_value('signcolumn', 'auto', {})
+    api.nvim_buf_set_extmark(0, ns, 0, 0, {sign_text='S1', invalidate=true})
+    feed('ia<cr>b<esc>dd')
+    screen:expect({
+      grid = [[
+        ^a                                                 |
+        {1:~                                                 }|*8
+                                                          |
+      ]]
+    })
+  end)
 end)
 
 describe('decorations: virt_text', function()

test/functional/vimscript/fnamemodify_spec.lua

@@ -7,11 +7,10 @@ local fnamemodify = n.fn.fnamemodify
 local getcwd = n.fn.getcwd
 local command = n.command
 local write_file = t.write_file
-local alter_slashes = n.alter_slashes
 local is_os = t.is_os
 
 local function eq_slashconvert(expected, got)
-  eq(alter_slashes(expected), alter_slashes(got))
+  eq(t.fix_slashes(expected), t.fix_slashes(got))
 end
 
 describe('fnamemodify()', function()

test/old/testdir/test_breakindent.vim

@@ -837,18 +837,73 @@ func Test_breakindent20_list()
 	\ ]
   let lines = s:screen_lines2(1, 9, 20)
   call s:compare_lines(expect, lines)
+
+  " check with TABs
+  call setline(1, ["\t1.\tCongress shall make no law",
+        \ "\t2.) Congress shall make no law",
+        \ "\t3.] Congress shall make no law"])
+  setl tabstop=4 list listchars=tab:<->
+  norm! 1gg
+  redraw!
+  let expect = [
+	\ "<-->1.<>Congress    ",
+	\ "        shall make  ",
+	\ "        no law      ",
+	\ "<-->2.) Congress    ",
+	\ "        shall make  ",
+	\ "        no law      ",
+	\ "<-->3.] Congress    ",
+	\ "        shall make  ",
+	\ "        no law      ",
+	\ ]
+  let lines = s:screen_lines2(1, 9, 20)
+  call s:compare_lines(expect, lines)
+
+  setl tabstop=2 nolist
+  redraw!
+  let expect = [
+	\ "  1.  Congress      ",
+	\ "      shall make no ",
+	\ "      law           ",
+	\ "  2.) Congress      ",
+	\ "      shall make no ",
+	\ "      law           ",
+	\ "  3.] Congress      ",
+	\ "      shall make no ",
+	\ "      law           ",
+	\ ]
+  let lines = s:screen_lines2(1, 9, 20)
+  call s:compare_lines(expect, lines)
+
+  setl tabstop& list listchars=space:_
+  redraw!
+  let expect = [
+	\ "^I1.^ICongress_     ",
+	\ "      shall_make_no_",
+	\ "      law           ",
+	\ "^I2.)_Congress_     ",
+	\ "      shall_make_no_",
+	\ "      law           ",
+	\ "^I3.]_Congress_     ",
+	\ "      shall_make_no_",
+	\ "      law           ",
+	\ ]
+  let lines = s:screen_lines2(1, 9, 20)
+  call s:compare_lines(expect, lines)
+
   " check formatlistpat indent with different list levels
-  let &l:flp = '^\s*\*\+\s\+'
+  let &l:flp = '^\s*\(\*\|•\)\+\s\+'
+  setl list&vim listchars&vim
   %delete _
   call setline(1, ['* Congress shall make no law',
-        \ '*** Congress shall make no law',
+        \ '••• Congress shall make no law',
         \ '**** Congress shall make no law'])
   norm! 1gg
   redraw!
   let expect = [
 	\ "* Congress shall    ",
 	\ "  make no law       ",
-	\ "*** Congress shall  ",
+	\ "••• Congress shall  ",
 	\ "    make no law     ",
 	\ "**** Congress shall ",
 	\ "     make no law    ",
@@ -864,7 +919,7 @@ func Test_breakindent20_list()
   let expect = [
 	\ "* Congress shall    ",
 	\ "> make no law       ",
-	\ "*** Congress shall  ",
+	\ "••• Congress shall  ",
 	\ ">   make no law     ",
 	\ "**** Congress shall ",
 	\ ">    make no law    ",
@@ -880,7 +935,7 @@ func Test_breakindent20_list()
   let expect = [
 	\ "* Congress shall    ",
 	\ ">   make no law     ",
-	\ "*** Congress shall  ",
+	\ "••• Congress shall  ",
 	\ ">     make no law   ",
 	\ "**** Congress shall ",
 	\ ">      make no law  ",

test/old/testdir/test_utf8.vim

@@ -228,6 +228,9 @@ func Test_setcellwidths()
     call setcellwidths([[0x2103, 0x2103, 2]])
     redraw
     call assert_equal(19, wincol())
+    call setcellwidths([])
+    redraw
+    call assert_equal((aw == 'single') ? 10 : 19, wincol())
   endfor
   set ambiwidth& isprint&
 
@@ -252,15 +255,21 @@ func Test_setcellwidths()
 
   call assert_fails('call setcellwidths([[0x33, 0x44, 2]])', 'E1114:')
 
-  set listchars=tab:--\\u2192
+  set listchars=tab:--\\u2192 fillchars=stl:\\u2501
   call assert_fails('call setcellwidths([[0x2192, 0x2192, 2]])', 'E834:')
-
-  set fillchars=stl:\\u2501
   call assert_fails('call setcellwidths([[0x2501, 0x2501, 2]])', 'E835:')
 
+  call setcellwidths([[0x201c, 0x201d, 1]])
+  set listchars& fillchars& ambiwidth=double
+
+  set listchars=nbsp:\\u201c fillchars=vert:\\u201d
+  call assert_fails('call setcellwidths([])', 'E834:')
   set listchars&
+  call assert_fails('call setcellwidths([])', 'E835:')
   set fillchars&
+
   call setcellwidths([])
+  set ambiwidth&
   bwipe!
 endfunc
 

test/testutil.lua

@@ -16,7 +16,7 @@ local function shell_quote(str)
   return str
 end
 
---- This module uses functions from the context of the test runner.
+--- Functions executing in the context of the test runner (not the current nvim test session).
 --- @class test.testutil
 local M = {
   paths = Paths,
@@ -42,6 +42,29 @@ function M.isdir(path)
   return stat.type == 'directory'
 end
 
+--- (Only on Windows) Replaces yucky "\\" slashes with delicious "/" slashes in a string, or all
+--- string values in a table (recursively).
+---
+--- @param obj string|table
+--- @return any
+function M.fix_slashes(obj)
+  if not M.is_os('win') then
+    return obj
+  end
+  if type(obj) == 'string' then
+    local ret = obj:gsub('\\', '/')
+    return ret
+  elseif type(obj) == 'table' then
+    --- @cast obj table<any,any>
+    local ret = {} --- @type table<any,any>
+    for k, v in pairs(obj) do
+      ret[k] = M.fix_slashes(v)
+    end
+    return ret
+  end
+  assert(false, 'expected string or table of strings, got ' .. type(obj))
+end
+
 --- @param ... string|string[]
 --- @return string
 function M.argss_to_cmd(...)

test/unit/mbyte_spec.lua

@@ -4,7 +4,6 @@ local itp = t.gen_itp(it)
 local ffi = t.ffi
 local eq = t.eq
 local to_cstr = t.to_cstr
-local ok = t.ok
 
 local lib = t.cimport(
   './src/nvim/mbyte.h',
@@ -302,7 +301,10 @@ describe('mbyte', function()
       local mb_glyphs = {}
       while pos < len do
         local clen = lib.utfc_ptr2len(cstr + pos)
-        ok(clen > 0) -- otherwise we get stuck
+        if clen == 0 then
+          eq(0, string.byte(str, pos + 1)) -- only NUL bytes can has length zery
+          clen = 1 -- but skip it, otherwise we get stuck
+        end
         if clen > 1 then
           table.insert(mb_glyphs, string.sub(str, pos + 1, pos + clen))
         end
@@ -325,13 +327,18 @@ describe('mbyte', function()
     -- stylua doesn't like ZWJ chars..
     -- stylua: ignore start
     check('hej och hå 🧑‍🌾!', { 'å', '🧑‍🌾' })
-    -- emoji only (various kinds of combinations, use g8 to see them)
+
+    -- emoji (various kinds of combinations, use g8 to see them)
     check("🏳️‍⚧️🧑‍🌾❤️😂🏴‍☠️", {"🏳️‍⚧️", "🧑‍🌾", "❤️", "😂", "🏴‍☠️"})
     check('🏳️‍⚧️xy🧑‍🌾\r❤️😂å🏴‍☠️€', { '🏳️‍⚧️', '🧑‍🌾', '❤️', '😂', 'å', '🏴‍☠️', '€' })
+    check('🏳️‍⚧️\000🧑‍🌾\000❤️\000😂\000å\000🏴‍☠️\000€', { '🏳️‍⚧️', '🧑‍🌾', '❤️', '😂', 'å', '🏴‍☠️', '€' })
+    check('\195🏳️‍⚧️\198🧑‍🌾\165❤️\168\195😂\255🏴‍☠️\129€\165', { '🏳️‍⚧️', '🧑‍🌾', '❤️', '😂', '🏴‍☠️', '€' })
 
     check('🇦🅱️ 🇦🇽 🇦🇨🇦 🇲🇽🇹🇱',{'🇦', '🅱️', '🇦🇽', '🇦🇨', '🇦', '🇲🇽', '🇹🇱'})
     check('🏴󠁧󠁢󠁳󠁣󠁴󠁿🏴󠁧󠁢󠁷󠁬󠁳󠁿', {'🏴󠁧󠁢󠁳󠁣󠁴󠁿', '🏴󠁧󠁢󠁷󠁬󠁳󠁿'})
 
+    check('å\165ü\195aëq\168β\000\169本\255', {'å', 'ü', 'ë', 'β', '本'})
+
     lib.p_arshape = true -- default
     check('سلام', { 'س', 'لا', 'م' })
     lib.p_arshape = false