vim-patch:9.1.0049: Make "[Command Line]" a special buffer name

Problem:  E95 is possible if a buffer called "[Command Line]" already
          exists when opening the cmdwin. This can also happen if the
          cmdwin's buffer could not be deleted when closing.

Solution: Un-name the cmdwin buffer, and give it a special name instead,
          similar to what's done for quickfix buffers and for unnamed
          prompt and scratch buffers. As a result, BufFilePre/Post are
          no longer fired when opening the cmdwin. Add a "command" key
          to the dictionary returned by getbufinfo() to differentiate
          the cmdwin buffer instead. (Sean Dewar)

Cherry-pick test_normal changes from v9.0.0954.

1fb4103206

runtime/doc/builtin.txt

@@ -2079,6 +2079,8 @@ getbufinfo([{dict}])                                              *getbufinfo()*
 			bufnr		Buffer number.
 			changed		TRUE if the buffer is modified.
 			changedtick	Number of changes made to the buffer.
+			command		TRUE if the buffer belongs to the
+					command-line window |cmdwin|.
 			hidden		TRUE if the buffer is hidden.
 			lastused	Timestamp in seconds, like
 					|localtime()|, when the buffer was

runtime/lua/vim/_meta/vimfn.lua

@@ -2562,6 +2562,8 @@ function vim.fn.getbufinfo(buf) end
 ---   bufnr    Buffer number.
 ---   changed    TRUE if the buffer is modified.
 ---   changedtick  Number of changes made to the buffer.
+---   command    TRUE if the buffer belongs to the
+---       command-line window |cmdwin|.
 ---   hidden    TRUE if the buffer is hidden.
 ---   lastused  Timestamp in seconds, like
 ---       |localtime()|, when the buffer was

src/nvim/buffer.c

@@ -4012,6 +4012,9 @@ char *buf_spname(buf_T *buf)
     if (buf->b_fname != NULL) {
       return buf->b_fname;
     }
+    if (buf == cmdwin_buf) {
+      return _("[Command Line]");
+    }
     if (bt_prompt(buf)) {
       return _("[Prompt]");
     }
@@ -4129,6 +4132,7 @@ void wipe_buffer(buf_T *buf, bool aucmd)
 ///   - Always considered 'nomodified'
 ///
 /// @param bufnr     Buffer to switch to, or 0 to create a new buffer.
+/// @param bufname   Buffer name, or NULL.
 ///
 /// @see curbufIsChanged()
 ///
@@ -4138,9 +4142,11 @@ int buf_open_scratch(handle_T bufnr, char *bufname)
   if (do_ecmd((int)bufnr, NULL, NULL, NULL, ECMD_ONE, ECMD_HIDE, NULL) == FAIL) {
     return FAIL;
   }
-  apply_autocmds(EVENT_BUFFILEPRE, NULL, NULL, false, curbuf);
-  setfname(curbuf, bufname, NULL, true);
-  apply_autocmds(EVENT_BUFFILEPOST, NULL, NULL, false, curbuf);
+  if (bufname != NULL) {
+    apply_autocmds(EVENT_BUFFILEPRE, NULL, NULL, false, curbuf);
+    setfname(curbuf, bufname, NULL, true);
+    apply_autocmds(EVENT_BUFFILEPOST, NULL, NULL, false, curbuf);
+  }
   set_option_value_give_err(kOptBufhidden, STATIC_CSTR_AS_OPTVAL("hide"), OPT_LOCAL);
   set_option_value_give_err(kOptBuftype, STATIC_CSTR_AS_OPTVAL("nofile"), OPT_LOCAL);
   set_option_value_give_err(kOptSwapfile, BOOLEAN_OPTVAL(false), OPT_LOCAL);

src/nvim/eval.lua

@@ -3219,6 +3219,8 @@ M.funcs = {
       	bufnr		Buffer number.
       	changed		TRUE if the buffer is modified.
       	changedtick	Number of changes made to the buffer.
+      	command		TRUE if the buffer belongs to the
+      			command-line window |cmdwin|.
       	hidden		TRUE if the buffer is hidden.
       	lastused	Timestamp in seconds, like
       			|localtime()|, when the buffer was

src/nvim/eval/buffer.c

@@ -494,6 +494,7 @@ static dict_T *get_buffer_info(buf_T *buf)
   tv_dict_add_nr(dict, S_LEN("changed"), bufIsChanged(buf));
   tv_dict_add_nr(dict, S_LEN("changedtick"), buf_get_changedtick(buf));
   tv_dict_add_nr(dict, S_LEN("hidden"), buf->b_ml.ml_mfp != NULL && buf->b_nwindows == 0);
+  tv_dict_add_nr(dict, S_LEN("command"), buf == cmdwin_buf);
 
   // Get a reference to buffer variables
   tv_dict_add_dict(dict, S_LEN("variables"), buf->b_vars);

src/nvim/ex_getln.c

@@ -4345,7 +4345,7 @@ static int open_cmdwin(void)
 
   // Create empty command-line buffer.  Be especially cautious of BufLeave
   // autocommands from do_ecmd(), as cmdwin restrictions do not apply to them!
-  const int newbuf_status = buf_open_scratch(0, _("[Command Line]"));
+  const int newbuf_status = buf_open_scratch(0, NULL);
   const bool cmdwin_valid = win_valid(cmdwin_win);
   if (newbuf_status == FAIL || !cmdwin_valid || curwin != cmdwin_win || !win_valid(old_curwin)
       || !bufref_valid(&old_curbuf) || old_curwin->w_buffer != old_curbuf.br_buf) {

test/old/testdir/test_cmdwin.vim

@@ -192,4 +192,17 @@ func Test_cmdwin_interrupted()
   delfunc CheckInterrupted
 endfunc
 
+func Test_cmdwin_existing_bufname()
+  func CheckName()
+    call assert_equal(1, getbufinfo('')[0].command)
+    call assert_equal(0, getbufinfo('[Command Line]')[0].command)
+    call assert_match('#a\s*"\[Command Line\]"', execute('ls'))
+    call assert_match('%a\s*"\[Command Line\]"', execute('ls'))
+  endfunc
+  file [Command Line]
+  call feedkeys("q::call CheckName()\<CR>:q\<CR>", 'ntx')
+  0file
+  delfunc CheckName
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

test/old/testdir/test_normal.vim

@@ -3167,15 +3167,18 @@ endfunc
 func Test_normal50_commandline()
   CheckFeature timers
   CheckFeature cmdline_hist
+
   func! DoTimerWork(id)
-    call assert_equal('[Command Line]', bufname(''))
+    call assert_equal(1, getbufinfo('')[0].command)
+
     " should fail, with E11, but does fail with E23?
     "call feedkeys("\<c-^>", 'tm')
 
-    " should also fail with E11
+    " should fail with E11 - "Invalid in command-line window"
     call assert_fails(":wincmd p", 'E11')
-    " return from commandline window
-    call feedkeys("\<cr>")
+
+    " Return from commandline window.
+    call feedkeys("\<CR>", 't')
   endfunc
 
   let oldlang=v:lang
@@ -3188,7 +3191,9 @@ func Test_normal50_commandline()
   catch /E23/
     " no-op
   endtry
+
   " clean up
+  delfunc DoTimerWork
   set updatetime=4000
   exe "lang" oldlang
   bw!