Merge #10433 from erw7/vim-8.1.0027

vim-patch:8.1.{27,32,36,69,70,71,91,92}

runtime/doc/eval.txt

@@ -2084,6 +2084,7 @@ ctxsize()			Number	return |context-stack| size
 cursor({lnum}, {col} [, {off}])
 				Number	move cursor to {lnum}, {col}, {off}
 cursor({list})			Number	move cursor to position in {list}
+debugbreak({pid})		Number  interrupt process being debugged
 deepcopy({expr} [, {noref}])	any	make a full copy of {expr}
 delete({fname} [, {flags}])	Number	delete the file or directory {fname}
 deletebufline({expr}, {first}[, {last}])
@@ -2280,6 +2281,10 @@ pathshorten({expr})		String	shorten directory names in a path
 pow({x}, {y})			Float	{x} to the power of {y}
 prevnonblank({lnum})		Number	line nr of non-blank line <= {lnum}
 printf({fmt}, {expr1}...)	String	format text
+prompt_addtext({buf}, {expr})	none	add text to a prompt buffer
+prompt_setcallback({buf}, {expr}) none	set prompt callback function
+prompt_setinterrupt({buf}, {text}) none	set prompt interrupt function
+prompt_setprompt({buf}, {text}) none	set prompt text
 pum_getpos()			Dict	position and size of pum if visible
 pumvisible()			Number	whether popup menu is visible
 pyeval({expr})			any	evaluate |Python| expression
@@ -2290,7 +2295,7 @@ range({expr} [, {max} [, {stride}]])
 readdir({dir} [, {expr}])	List	file names in {dir} selected by {expr}
 readfile({fname} [, {binary} [, {max}]])
 				List	get list of lines from file {fname}
-reg_executing()			Number	get the executing register name
+reg_executing()			String	get the executing register name
 reg_recording()			String	get the recording register name
 reltime([{start} [, {end}]])	List	get time value
 reltimefloat({time})		Float	turn the time value into a Float
@@ -3637,6 +3642,11 @@ exp({expr})						*exp()*
 			:echo exp(-1)
 <			0.367879
 
+debugbreak({pid})					*debugbreak()*
+		Specifically used to interrupt a program being debugged.  It
+		will cause process {pid} to get a SIGTRAP.  Behavior for other
+		processes is undefined. See |terminal-debugger|.
+		{Sends a SIGINT to a process {pid} other than MS-Windows}
 
 expand({expr} [, {nosuf} [, {list}]])				*expand()*
 		Expand wildcards and the following special keywords in {expr}.
@@ -4541,7 +4551,7 @@ getline({lnum} [, {end}])
 		from the current buffer.  Example: >
 			getline(1)
 <		When {lnum} is a String that doesn't start with a
-		digit, line() is called to translate the String into a Number.
+		digit, |line()| is called to translate the String into a Number.
 		To get the line under the cursor: >
 			getline(".")
 <		When {lnum} is smaller than 1 or bigger than the number of
@@ -6541,6 +6551,50 @@ printf({fmt}, {expr1} ...)				*printf()*
 		of "%" items.  If there are not sufficient or too many
 		arguments an error is given.  Up to 18 arguments can be used.
 
+prompt_setcallback({buf}, {expr})			*prompt_setcallback()*
+		Set prompt callback for buffer {buf} to {expr}.  When {expr}
+		is an empty string the callback is removed.  This has only
+		effect if {buf} has 'buftype' set to "prompt".
+
+		The callback is invoked when pressing Enter.  The current
+		buffer will always be the prompt buffer.  A new line for a
+		prompt is added before invoking the callback, thus the prompt
+		for which the callback was invoked will be in the last but one
+		line.
+		If the callback wants to add text to the buffer, it must
+		insert it above the last line, since that is where the current
+		prompt is.  This can also be done asynchronously.
+		The callback is invoked with one argument, which is the text
+		that was entered at the prompt.  This can be an empty string
+		if the user only typed Enter.
+		Example: >
+		   call prompt_setcallback(bufnr(''), function('s:TextEntered'))
+		   func s:TextEntered(text)
+		     if a:text == 'exit' || a:text == 'quit'
+		       stopinsert
+		       close
+		     else
+		       call append(line('$') - 1, 'Entered: "' . a:text . '"')
+		       " Reset 'modified' to allow the buffer to be closed.
+		       set nomodified
+		     endif
+		   endfunc
+
+prompt_setinterrupt({buf}, {expr})			*prompt_setinterrupt()*
+		Set a callback for buffer {buf} to {expr}.  When {expr} is an
+		empty string the callback is removed.  This has only effect if
+		{buf} has 'buftype' set to "prompt".
+
+		This callback will be invoked when pressing CTRL-C in Insert
+		mode.  Without setting a callback Vim will exit Insert mode,
+		as in any buffer.
+
+prompt_setprompt({buf}, {text})				*prompt_setprompt()*
+		Set prompt for buffer {buf} to {text}.  You most likely want
+		{text} to end in a space.
+		The result is only visible if {buf} has 'buftype' set to
+		"prompt".  Example: >
+			call prompt_setprompt(bufnr(''), 'command: ')
 
 pum_getpos()						*pum_getpos()*
  		If the popup menu (see |ins-completion-menu|) is not visible,

runtime/doc/nvim_terminal_emulator.txt

@@ -307,6 +307,23 @@ Other commands ~
 	     isn't one
 
 
+Prompt mode ~
+						*termdebug-prompt*
+When on MS-Windows, gdb will run in a buffer with 'buftype' set to "prompt".
+This works slightly differently:
+- The gdb window will be in Insert mode while typing commands.  Go to Normal
+  mode with <Esc>, then you can move around in the buffer, copy/paste, etc.
+  Go back to editing the gdb command with any command that starts Insert mode,
+  such as `a` or `i`.
+- The program being debugged will run in a separate window.  On MS-Windows
+  this is a new console window.  On Unix, if the |+terminal| feature is
+  available a Terminal window will be opened to run the debugged program in.
+
+						*termdebug_use_prompt*
+Prompt mode can be used even when the |+terminal| feature is present with: >
+	let g:termdebug_use_prompt = 1
+
+
 Communication ~
 						*termdebug-communication*
 There is another, hidden, buffer, which is used for Vim to communicate with

runtime/doc/options.txt

@@ -1093,6 +1093,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  nowrite	buffer will not be written
 	  quickfix	list of errors |:cwindow| or locations |:lwindow|
 	  terminal	|terminal-emulator| buffer
+	  prompt	buffer where only the last line can be edited, meant
+			to be used by a plugin, see |prompt-buffer|
 
 	This option is used together with 'bufhidden' and 'swapfile' to
 	specify special kinds of buffers.   See |special-buffers|.

runtime/pack/dist/opt/termdebug/plugin/termdebug.vim

@@ -37,7 +37,7 @@
 " For neovim compatibility, the vim specific calls were replaced with neovim
 " specific calls:
 "   term_start -> term_open
-"   term_sendkeys -> jobsend
+"   term_sendkeys -> chansend
 "   term_getline -> getbufline
 "   job_info && term_getjob -> using linux command ps to get the tty
 "   balloon -> nvim floating window
@@ -47,8 +47,6 @@
 " https://github.com/autozimu/LanguageClient-neovim/blob/0ed9b69dca49c415390a8317b19149f97ae093fa/autoload/LanguageClient.vim#L304
 "
 " Neovim terminal also works seamlessly on windows, which is why the ability
-" to use the prompt buffer was removed.
-"
 " Author: Bram Moolenaar
 " Copyright: Vim license applies, see ":help license"
 
@@ -57,6 +55,12 @@ if exists(':Termdebug')
   finish
 endif
 
+" The terminal feature does not work with gdb on win32.
+if !has('win32')
+  let s:way = 'terminal'
+else
+  let s:way = 'prompt'
+endif
 
 let s:keepcpo = &cpo
 set cpo&vim
@@ -138,7 +142,19 @@ func s:StartDebug_internal(dict)
     let s:vertical = 0
   endif
 
+  " Override using a terminal window by setting g:termdebug_use_prompt to 1.
+  let use_prompt = exists('g:termdebug_use_prompt') && g:termdebug_use_prompt
+  if !has('win32') && !use_prompt
+    let s:way = 'terminal'
+   else
+    let s:way = 'prompt'
+   endif
+
+  if s:way == 'prompt'
+    call s:StartDebug_prompt(a:dict)
+  else
     call s:StartDebug_term(a:dict)
+  endif
 endfunc
 
 " Use when debugger didn't start or ended.
@@ -214,11 +230,11 @@ func s:StartDebug_term(dict)
 
   " Set arguments to be run
   if len(proc_args)
-    call jobsend(s:gdb_job_id, 'set args ' . join(proc_args) . "\r")
+    call chansend(s:gdb_job_id, 'set args ' . join(proc_args) . "\r")
   endif
 
   " Connect gdb to the communication pty, using the GDB/MI interface
-  call jobsend(s:gdb_job_id, 'new-ui mi ' . commpty . "\r")
+  call chansend(s:gdb_job_id, 'new-ui mi ' . commpty . "\r")
 
   " Wait for the response to show up, users may not notice the error and wonder
   " why the debugger doesn't work.
@@ -275,6 +291,100 @@ func s:StartDebug_term(dict)
   call s:StartDebugCommon(a:dict)
 endfunc
 
+func s:StartDebug_prompt(dict)
+  " Open a window with a prompt buffer to run gdb in.
+  if s:vertical
+    vertical new
+  else
+    new
+  endif
+  let s:gdbwin = win_getid(winnr())
+  let s:promptbuf = bufnr('')
+  call prompt_setprompt(s:promptbuf, 'gdb> ')
+  set buftype=prompt
+  file gdb
+  call prompt_setcallback(s:promptbuf, function('s:PromptCallback'))
+  call prompt_setinterrupt(s:promptbuf, function('s:PromptInterrupt'))
+
+  if s:vertical
+    " Assuming the source code window will get a signcolumn, use two more
+    " columns for that, thus one less for the terminal window.
+    exe (&columns / 2 - 1) . "wincmd |"
+  endif
+
+  " Add -quiet to avoid the intro message causing a hit-enter prompt.
+  let gdb_args = get(a:dict, 'gdb_args', [])
+  let proc_args = get(a:dict, 'proc_args', [])
+
+  let cmd = [g:termdebugger, '-quiet', '--interpreter=mi2'] + gdb_args
+  "call ch_log('executing "' . join(cmd) . '"')
+
+  let s:gdbjob = jobstart(cmd, {
+	\ 'on_exit': function('s:EndPromptDebug'),
+	\ 'on_stdout': function('s:GdbOutCallback'),
+	\ })
+  if s:gdbjob == 0
+    echoerr 'invalid argument (or job table is full) while starting gdb job'
+    exe 'bwipe! ' . s:ptybuf
+    return
+  elseif s:gdbjob == -1
+    echoerr 'Failed to start the gdb job'
+    call s:CloseBuffers()
+    return
+  endif
+
+  " Interpret commands while the target is running.  This should usualy only
+  " be exec-interrupt, since many commands don't work properly while the
+  " target is running.
+  call s:SendCommand('-gdb-set mi-async on')
+  " Older gdb uses a different command.
+  call s:SendCommand('-gdb-set target-async on')
+
+  let s:ptybuf = 0
+  if has('win32')
+    " MS-Windows: run in a new console window for maximum compatibility
+    call s:SendCommand('set new-console on')
+  else
+    " Unix: Run the debugged program in a terminal window.  Open it below the
+    " gdb window.
+    execute 'new'
+    wincmd x | wincmd j
+    belowright let s:pty_job_id = termopen('tail -f /dev/null;#gdb program')
+    if s:pty_job_id == 0
+      echoerr 'invalid argument (or job table is full) while opening terminal window'
+      return
+    elseif s:pty_job_id == -1
+      echoerr 'Failed to open the program terminal window'
+      return
+    endif
+    let pty_job_info = nvim_get_chan_info(s:pty_job_id)
+    let s:ptybuf = pty_job_info['buffer']
+    let pty = pty_job_info['pty']
+    let s:ptywin = win_getid(winnr())
+    call s:SendCommand('tty ' . pty)
+
+    " Since GDB runs in a prompt window, the environment has not been set to
+    " match a terminal window, need to do that now.
+    call s:SendCommand('set env TERM = xterm-color')
+    call s:SendCommand('set env ROWS = ' . winheight(s:ptywin))
+    call s:SendCommand('set env LINES = ' . winheight(s:ptywin))
+    call s:SendCommand('set env COLUMNS = ' . winwidth(s:ptywin))
+    call s:SendCommand('set env COLORS = ' . &t_Co)
+    call s:SendCommand('set env VIM_TERMINAL = ' . v:version)
+  endif
+  call s:SendCommand('set print pretty on')
+  call s:SendCommand('set breakpoint pending on')
+  " Disable pagination, it causes everything to stop at the gdb
+  call s:SendCommand('set pagination off')
+
+  " Set arguments to be run
+  if len(proc_args)
+    call s:SendCommand('set args ' . join(proc_args))
+  endif
+
+  call s:StartDebugCommon(a:dict)
+  startinsert
+endfunc
 
 func s:StartDebugCommon(dict)
   " Sign used to highlight the line where the program has stopped.
@@ -316,21 +426,97 @@ endfunc
 " Send a command to gdb.  "cmd" is the string without line terminator.
 func s:SendCommand(cmd)
   "call ch_log('sending to gdb: ' . a:cmd)
-  call jobsend(s:comm_job_id, a:cmd . "\r")
+  if s:way == 'prompt'
+    call chansend(s:gdbjob, a:cmd . "\n")
+  else
+    call chansend(s:comm_job_id, a:cmd . "\r")
+  endif
 endfunc
 
 " This is global so that a user can create their mappings with this.
 func TermDebugSendCommand(cmd)
+  if s:way == 'prompt'
+    call chansend(s:gdbjob, a:cmd . "\n")
+  else
     let do_continue = 0
     if !s:stopped
       let do_continue = 1
+      if s:way == 'prompt'
+        " Need to send a signal to get the UI to listen.  Strangely this is only
+        " needed once.
+        call jobstop(s:gdbjob)
+      else
         call s:SendCommand('-exec-interrupt')
+      endif
       sleep 10m
     endif
-  call jobsend(s:gdb_job_id, a:cmd . "\r")
+    call chansend(s:gdb_job_id, a:cmd . "\r")
     if do_continue
       Continue
     endif
+  endif
+endfunc
+
+" Function called when entering a line in the prompt buffer.
+func s:PromptCallback(text)
+  call s:SendCommand(a:text)
+endfunc
+
+" Function called when pressing CTRL-C in the prompt buffer and when placing a
+" breakpoint.
+func s:PromptInterrupt()
+  if s:pid == 0
+    echoerr 'Cannot interrupt gdb, did not find a process ID'
+  else
+    "call ch_log('Interrupting gdb')
+    " Using job_stop(s:gdbjob, 'int') does not work.
+    call debugbreak(s:pid)
+  endif
+endfunc
+
+" Function called when gdb outputs text.
+func s:GdbOutCallback(job_id, msgs, event)
+  "call ch_log('received from gdb: ' . a:text)
+
+  " Drop the gdb prompt, we have our own.
+  " Drop status and echo'd commands.
+  call filter(a:msgs, { index, val ->
+        \ val !=# '(gdb)' && val !=# '^done' && val[0] !=# '&'})
+
+  let lines = []
+  let index = 0
+
+  for msg in a:msgs
+    if msg =~ '^^error,msg='
+      if exists('s:evalexpr')
+            \ && s:DecodeMessage(msg[11:])
+            \    =~ 'A syntax error in expression, near\|No symbol .* in current context'
+        " Silently drop evaluation errors.
+        call remove(a:msgs, index)
+        unlet s:evalexpr
+        continue
+      endif
+    elseif msg[0] == '~'
+      call add(lines, s:DecodeMessage(msg[1:]))
+      call remove(a:msgs, index)
+      continue
+    endif
+    let index += 1
+  endfor
+
+  let curwinid = win_getid(winnr())
+  call win_gotoid(s:gdbwin)
+
+  " Add the output above the current prompt.
+  for line in lines
+    call append(line('$') - 1, line)
+  endfor
+  if !empty(lines)
+    set modified
+  endif
+
+  call win_gotoid(curwinid)
+  call s:CommOutput(a:job_id, a:msgs, a:event)
 endfunc
 
 " Decode a message from gdb.  quotedText starts with a ", return the text up
@@ -396,6 +582,19 @@ func s:EndDebugCommon()
   au! TermDebug
 endfunc
 
+func s:EndPromptDebug(job_id, exit_code, event)
+  let curwinid = win_getid(winnr())
+  call win_gotoid(s:gdbwin)
+  close
+  if curwinid != s:gdbwin
+    call win_gotoid(curwinid)
+  endif
+
+  call s:EndDebugCommon()
+  unlet s:gdbwin
+  "call ch_log("Returning from EndPromptDebug()")
+endfunc
+
 func s:CommOutput(job_id, msgs, event)
 
   for msg in a:msgs
@@ -436,7 +635,11 @@ func s:InstallCommands()
   command Stop call s:SendCommand('-exec-interrupt')
 
   " using -exec-continue results in CTRL-C in gdb window not working
-  command Continue call jobsend(s:gdb_job_id, "continue\r")
+  if s:way == 'prompt'
+    command Continue call s:SendCommand('continue')
+  else
+    command Continue call chansend(s:gdb_job_id, "continue\r")
+  endif
 
   command -range -nargs=* Evaluate call s:Evaluate(<range>, <q-args>)
   command Gdb call win_gotoid(s:gdbwin)
@@ -494,7 +697,11 @@ func s:SetBreakpoint()
   let do_continue = 0
   if !s:stopped
     let do_continue = 1
+    if s:way == 'prompt'
+      call s:PromptInterrupt()
+    else
       call s:SendCommand('-exec-interrupt')
+    endif
     sleep 10m
   endif
   " Use the fname:lnum format, older gdb can't handle --source.

src/nvim/buffer.c

@@ -763,6 +763,9 @@ static void free_buffer(buf_T *buf)
   unref_var_dict(buf->b_vars);
   aubuflocal_remove(buf);
   tv_dict_unref(buf->additional_data);
+  xfree(buf->b_prompt_text);
+  callback_free(&buf->b_prompt_callback);
+  callback_free(&buf->b_prompt_interrupt);
   clear_fmark(&buf->b_last_cursor);
   clear_fmark(&buf->b_last_insert);
   clear_fmark(&buf->b_last_change);
@@ -1876,6 +1879,10 @@ buf_T * buflist_new(char_u *ffname, char_u *sfname, linenr_T lnum, int flags)
     }
   }
 
+  buf->b_prompt_callback.type = kCallbackNone;
+  buf->b_prompt_interrupt.type = kCallbackNone;
+  buf->b_prompt_text = NULL;
+
   return buf;
 }
 
@@ -4824,6 +4831,12 @@ do_arg_all(
   xfree(opened);
 }
 
+// Return TRUE if "buf" is a prompt buffer.
+int bt_prompt(buf_T *buf)
+{
+    return buf != NULL && buf->b_p_bt[0] == 'p';
+}
+
 /*
  * Open a window for a number of buffers.
  */
@@ -5218,14 +5231,18 @@ bool bt_nofile(const buf_T *const buf)
   FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
 {
   return buf != NULL && ((buf->b_p_bt[0] == 'n' && buf->b_p_bt[2] == 'f')
-                         || buf->b_p_bt[0] == 'a' || buf->terminal);
+                         || buf->b_p_bt[0] == 'a'
+                         || buf->terminal
+                         || buf->b_p_bt[0] == 'p');
 }
 
 // Return true if "buf" is a "nowrite", "nofile" or "terminal" buffer.
 bool bt_dontwrite(const buf_T *const buf)
   FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
 {
-  return buf != NULL && (buf->b_p_bt[0] == 'n' || buf->terminal);
+  return buf != NULL && (buf->b_p_bt[0] == 'n'
+                         || buf->terminal
+                         || buf->b_p_bt[0] == 'p');
 }
 
 bool bt_dontwrite_msg(const buf_T *const buf)
@@ -5278,6 +5295,9 @@ char_u *buf_spname(buf_T *buf)
     if (buf->b_fname != NULL) {
       return buf->b_fname;
     }
+    if (bt_prompt(buf)) {
+      return (char_u *)_("[Prompt]");
+    }
     return (char_u *)_("[Scratch]");
   }
   if (buf->b_fname == NULL) {

src/nvim/buffer_defs.h

@@ -791,6 +791,12 @@ struct file_buffer {
                                 // are not used!  Use the B_SPELL macro to
                                 // access b_spell without #ifdef.
 
+  char_u *b_prompt_text;        // set by prompt_setprompt()
+  Callback b_prompt_callback;   // set by prompt_setcallback()
+  Callback b_prompt_interrupt;  // set by prompt_setinterrupt()
+  int b_prompt_insert;          // value for restart_edit when entering
+                                // a prompt buffer window.
+
   synblock_T b_s;               // Info related to syntax highlighting.  w_s
                                 // normally points to this, but some windows
                                 // may use a different synblock_T.

src/nvim/diff.c

@@ -2432,6 +2432,10 @@ void nv_diffgetput(bool put, size_t count)
   exarg_T ea;
   char buf[30];
 
+  if (bt_prompt(curbuf)) {
+    vim_beep(BO_OPER);
+    return;
+  }
   if (count == 0) {
     ea.arg = (char_u *)"";
   } else {

src/nvim/edit.c

@@ -574,6 +574,12 @@ static int insert_check(VimState *state)
     foldCheckClose();
   }
 
+  int cmdchar_todo = s->cmdchar;
+  if (bt_prompt(curbuf)) {
+    init_prompt(cmdchar_todo);
+    cmdchar_todo = NUL;
+  }
+
   // If we inserted a character at the last position of the last line in the
   // window, scroll the window one line up. This avoids an extra redraw.  This
   // is detected when the cursor column is smaller after inserting something.
@@ -817,6 +823,16 @@ static int insert_handle_key(InsertState *s)
       s->nomove = true;
       return 0;  // exit insert mode
     }
+    if (s->c == Ctrl_C && bt_prompt(curbuf)) {
+      if (invoke_prompt_interrupt()) {
+        if (!bt_prompt(curbuf)) {
+          // buffer changed to a non-prompt buffer, get out of
+          // Insert mode
+          return 0;
+        }
+        break;
+      }
+    }
 
     // when 'insertmode' set, and not halfway through a mapping, don't leave
     // Insert mode
@@ -1143,6 +1159,15 @@ check_pum:
       cmdwin_result = CAR;
       return 0;
     }
+    if (bt_prompt(curbuf)) {
+      invoke_prompt_callback();
+      if (!bt_prompt(curbuf)) {
+        // buffer changed to a non-prompt buffer, get out of
+        // Insert mode
+        return 0;
+      }
+      break;
+    }
     if (!ins_eol(s->c) && !p_im) {
       return 0;  // out of memory
     }
@@ -1569,6 +1594,52 @@ void edit_putchar(int c, int highlight)
   }
 }
 
+// Return the effective prompt for the current buffer.
+char_u *prompt_text(void)
+{
+    if (curbuf->b_prompt_text == NULL) {
+      return (char_u *)"% ";
+    }
+    return curbuf->b_prompt_text;
+}
+
+// Prepare for prompt mode: Make sure the last line has the prompt text.
+// Move the cursor to this line.
+static void init_prompt(int cmdchar_todo)
+{
+  char_u *prompt = prompt_text();
+  char_u *text;
+
+  curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
+  text = get_cursor_line_ptr();
+  if (STRNCMP(text, prompt, STRLEN(prompt)) != 0) {
+    // prompt is missing, insert it or append a line with it
+    if (*text == NUL) {
+      ml_replace(curbuf->b_ml.ml_line_count, prompt, true);
+    } else {
+      ml_append(curbuf->b_ml.ml_line_count, prompt, 0, false);
+    }
+    curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
+    coladvance((colnr_T)MAXCOL);
+    changed_bytes(curbuf->b_ml.ml_line_count, 0);
+  }
+  if (cmdchar_todo == 'A') {
+    coladvance((colnr_T)MAXCOL);
+  }
+  if (cmdchar_todo == 'I' || curwin->w_cursor.col <= (int)STRLEN(prompt)) {
+    curwin->w_cursor.col = STRLEN(prompt);
+  }
+  // Make sure the cursor is in a valid position.
+  check_cursor();
+}
+
+// Return TRUE if the cursor is in the editable position of the prompt line.
+int prompt_curpos_editable(void)
+{
+    return curwin->w_cursor.lnum == curbuf->b_ml.ml_line_count
+        && curwin->w_cursor.col >= (int)STRLEN(prompt_text());
+}
+
 /*
  * Undo the previous edit_putchar().
  */
@@ -8161,10 +8232,14 @@ static void ins_mouse(int c)
     win_T   *new_curwin = curwin;
 
     if (curwin != old_curwin && win_valid(old_curwin)) {
-      /* Mouse took us to another window.  We need to go back to the
+      // Mouse took us to another window.  We need to go back to the
-       * previous one to stop insert there properly. */
+      // previous one to stop insert there properly.
       curwin = old_curwin;
       curbuf = curwin->w_buffer;
+      if (bt_prompt(curbuf)) {
+        // Restart Insert mode when re-entering the prompt buffer.
+        curbuf->b_prompt_insert = 'A';
+      }
     }
     start_arrow(curwin == old_curwin ? &tpos : NULL);
     if (curwin != new_curwin && win_valid(new_curwin)) {

src/nvim/eval.c

@@ -5152,6 +5152,10 @@ bool garbage_collect(bool testing)
     }
     // buffer ShaDa additional data
     ABORTING(set_ref_dict)(buf->additional_data, copyID);
+
+    // buffer callback functions
+    set_ref_in_callback(&buf->b_prompt_callback, copyID, NULL, NULL);
+    set_ref_in_callback(&buf->b_prompt_interrupt, copyID, NULL, NULL);
   }
 
   FOR_ALL_TAB_WINDOWS(tp, wp) {
@@ -7315,9 +7319,7 @@ dict_T *get_win_info(win_T *wp, int16_t tpnr, int16_t winnr)
   return dict;
 }
 
-/*
+// Find window specified by "vp" in tabpage "tp".
- * Find window specified by "vp" in tabpage "tp".
- */
 win_T *
 find_win_by_nr(
     typval_T *vp,
@@ -13687,3 +13689,51 @@ void ex_checkhealth(exarg_T *eap)
 
   xfree(buf);
 }
+
+void invoke_prompt_callback(void)
+{
+    typval_T rettv;
+    typval_T argv[2];
+    char_u *text;
+    char_u *prompt;
+    linenr_T lnum = curbuf->b_ml.ml_line_count;
+
+    // Add a new line for the prompt before invoking the callback, so that
+    // text can always be inserted above the last line.
+    ml_append(lnum, (char_u  *)"", 0, false);
+    curwin->w_cursor.lnum = lnum + 1;
+    curwin->w_cursor.col = 0;
+
+    if (curbuf->b_prompt_callback.type == kCallbackNone) {
+      return;
+    }
+    text = ml_get(lnum);
+    prompt = prompt_text();
+    if (STRLEN(text) >= STRLEN(prompt)) {
+      text += STRLEN(prompt);
+    }
+    argv[0].v_type = VAR_STRING;
+    argv[0].vval.v_string = vim_strsave(text);
+    argv[1].v_type = VAR_UNKNOWN;
+
+    callback_call(&curbuf->b_prompt_callback, 1, argv, &rettv);
+    tv_clear(&argv[0]);
+    tv_clear(&rettv);
+}
+
+// Return true When the interrupt callback was invoked.
+bool invoke_prompt_interrupt(void)
+{
+    typval_T rettv;
+    typval_T argv[1];
+
+    if (curbuf->b_prompt_interrupt.type == kCallbackNone) {
+      return false;
+    }
+    argv[0].v_type = VAR_UNKNOWN;
+
+    got_int = false;  // don't skip executing commands
+    callback_call(&curbuf->b_prompt_interrupt, 0, argv, &rettv);
+    tv_clear(&rettv);
+    return true;
+}

src/nvim/eval.lua

@@ -82,6 +82,7 @@ return {
     ctxset={args={1, 2}},
     ctxsize={},
     cursor={args={1, 3}},
+    debugbreak={args={1, 1}},
     deepcopy={args={1, 2}},
     delete={args={1,2}},
     deletebufline={args={2,3}},
@@ -243,6 +244,9 @@ return {
     pow={args=2},
     prevnonblank={args=1},
     printf={args=varargs(1)},
+    prompt_setcallback={args={2, 2}},
+    prompt_setinterrupt={args={2, 2}},
+    prompt_setprompt={args={2, 2}},
     pum_getpos={},
     pumvisible={},
     py3eval={args=1},

src/nvim/eval/funcs.c

@@ -1408,9 +1408,31 @@ static void f_cursor(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   rettv->vval.v_number = 0;
 }
 
-/*
+// "debugbreak()" function
- * "deepcopy()" function
+static void f_debugbreak(typval_T *argvars, typval_T *rettv, FunPtr fptr)
- */
+{
+  int pid;
+
+  rettv->vval.v_number = FAIL;
+  pid = (int)tv_get_number(&argvars[0]);
+  if (pid == 0) {
+    EMSG(_(e_invarg));
+  } else {
+#ifdef WIN32
+    HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, 0, pid);
+
+    if (hProcess != NULL) {
+      DebugBreakProcess(hProcess);
+      CloseHandle(hProcess);
+      rettv->vval.v_number = OK;
+    }
+#else
+    uv_kill(pid, SIGINT);
+#endif
+  }
+}
+
+// "deepcopy()" function
 static void f_deepcopy(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
   int noref = 0;
@@ -6076,6 +6098,76 @@ static void f_printf(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 }
 
+// "prompt_setcallback({buffer}, {callback})" function
+static void f_prompt_setcallback(typval_T *argvars,
+                                 typval_T *rettv, FunPtr fptr)
+{
+    buf_T *buf;
+    Callback prompt_callback = { .type = kCallbackNone };
+
+    if (check_secure()) {
+      return;
+    }
+    buf = tv_get_buf(&argvars[0], false);
+    if (buf == NULL) {
+      return;
+    }
+
+    if (argvars[1].v_type != VAR_STRING || *argvars[1].vval.v_string != NUL) {
+      if (!callback_from_typval(&prompt_callback, &argvars[1])) {
+        return;
+      }
+    }
+
+    callback_free(&buf->b_prompt_callback);
+    buf->b_prompt_callback = prompt_callback;
+}
+
+// "prompt_setinterrupt({buffer}, {callback})" function
+static void f_prompt_setinterrupt(typval_T *argvars,
+                                  typval_T *rettv, FunPtr fptr)
+{
+    buf_T *buf;
+    Callback interrupt_callback = { .type = kCallbackNone };
+
+    if (check_secure()) {
+      return;
+    }
+    buf = tv_get_buf(&argvars[0], false);
+    if (buf == NULL) {
+      return;
+    }
+
+    if (argvars[1].v_type != VAR_STRING || *argvars[1].vval.v_string != NUL) {
+      if (!callback_from_typval(&interrupt_callback, &argvars[1])) {
+        return;
+      }
+    }
+
+    callback_free(&buf->b_prompt_interrupt);
+    buf->b_prompt_interrupt= interrupt_callback;
+}
+
+// "prompt_setprompt({buffer}, {text})" function
+static void f_prompt_setprompt(typval_T *argvars,
+                               typval_T *rettv, FunPtr fptr)
+{
+    buf_T *buf;
+    const char_u *text;
+
+    if (check_secure()) {
+      return;
+    }
+    buf = tv_get_buf(&argvars[0], false);
+    if (buf == NULL) {
+      return;
+    }
+
+    text = (const char_u *)tv_get_string(&argvars[1]);
+    xfree(buf->b_prompt_text);
+    buf->b_prompt_text = vim_strsave(text);
+}
+
 // "pum_getpos()" function
 static void f_pum_getpos(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {

src/nvim/normal.c

@@ -3642,7 +3642,9 @@ static void nv_help(cmdarg_T *cap)
  */
 static void nv_addsub(cmdarg_T *cap)
 {
-  if (!VIsual_active && cap->oap->op_type == OP_NOP) {
+  if (bt_prompt(curbuf) && !prompt_curpos_editable()) {
+    clearopbeep(cap->oap);
+  } else if (!VIsual_active && cap->oap->op_type == OP_NOP) {
     prep_redo_cmd(cap);
     cap->oap->op_type = cap->cmdchar == Ctrl_A ? OP_NR_ADD : OP_NR_SUB;
     op_addsub(cap->oap, cap->count1, cap->arg);
@@ -5239,6 +5241,13 @@ static void nv_down(cmdarg_T *cap)
     // In the cmdline window a <CR> executes the command.
     if (cmdwin_type != 0 && cap->cmdchar == CAR) {
       cmdwin_result = CAR;
+    } else if (bt_prompt(curbuf) && cap->cmdchar == CAR
+               && curwin->w_cursor.lnum == curbuf->b_ml.ml_line_count) {
+      // In a prompt buffer a <CR> in the last line invokes the callback.
+      invoke_prompt_callback();
+      if (restart_edit == 0) {
+        restart_edit = 'a';
+      }
     } else {
       cap->oap->motion_type = kMTLineWise;
       if (cursor_down(cap->count1, cap->oap->op_type == OP_NOP) == false) {
@@ -5831,6 +5840,10 @@ static void nv_undo(cmdarg_T *cap)
 static void nv_kundo(cmdarg_T *cap)
 {
   if (!checkclearopq(cap->oap)) {
+    if (bt_prompt(curbuf)) {
+      clearopbeep(cap->oap);
+      return;
+    }
     u_undo((int)cap->count1);
     curwin->w_set_curswant = true;
   }
@@ -5844,8 +5857,13 @@ static void nv_replace(cmdarg_T *cap)
   char_u      *ptr;
   int had_ctrl_v;
 
-  if (checkclearop(cap->oap))
+  if (checkclearop(cap->oap)) {
     return;
+  }
+  if (bt_prompt(curbuf) && !prompt_curpos_editable()) {
+    clearopbeep(cap->oap);
+    return;
+  }
 
   /* get another character */
   if (cap->nchar == Ctrl_V) {
@@ -6182,7 +6200,11 @@ static void v_visop(cmdarg_T *cap)
  */
 static void nv_subst(cmdarg_T *cap)
 {
-  if (VIsual_active) {  /* "vs" and "vS" are the same as "vc" */
+  if (bt_prompt(curbuf) && !prompt_curpos_editable()) {
+    clearopbeep(cap->oap);
+    return;
+  }
+  if (VIsual_active) {  // "vs" and "vS" are the same as "vc"
     if (cap->cmdchar == 'S') {
       VIsual_mode_orig = VIsual_mode;
       VIsual_mode = 'V';
@@ -7120,11 +7142,16 @@ static void nv_tilde(cmdarg_T *cap)
 {
   if (!p_to
       && !VIsual_active
-      && cap->oap->op_type != OP_TILDE)
+      && cap->oap->op_type != OP_TILDE) {
+    if (bt_prompt(curbuf) && !prompt_curpos_editable()) {
+      clearopbeep(cap->oap);
+      return;
+    }
     n_swapchar(cap);
-  else
+  } else {
     nv_operator(cap);
   }
+}
 
 /*
  * Handle an operator command.
@@ -7136,6 +7163,12 @@ static void nv_operator(cmdarg_T *cap)
 
   op_type = get_op_type(cap->cmdchar, cap->nchar);
 
+  if (bt_prompt(curbuf) && op_is_change(op_type)
+      && !prompt_curpos_editable()) {
+    clearopbeep(cap->oap);
+    return;
+  }
+
   if (op_type == cap->oap->op_type)         /* double operator works on lines */
     nv_lineop(cap);
   else if (!checkclearop(cap->oap)) {
@@ -7796,7 +7829,10 @@ static void nv_put_opt(cmdarg_T *cap, bool fix_indent)
       clearop(cap->oap);
       assert(cap->opcount >= 0);
       nv_diffgetput(true, (size_t)cap->opcount);
-    } else
+    } else {
+      clearopbeep(cap->oap);
+    }
+  } else if (bt_prompt(curbuf) && !prompt_curpos_editable()) {
     clearopbeep(cap->oap);
   } else {
     if (fix_indent) {
@@ -7809,8 +7845,9 @@ static void nv_put_opt(cmdarg_T *cap, bool fix_indent)
         ? BACKWARD : FORWARD;
     }
     prep_redo_cmd(cap);
-    if (cap->cmdchar == 'g')
+    if (cap->cmdchar == 'g') {
       flags |= PUT_CURSEND;
+    }
 
     if (VIsual_active) {
       /* Putting in Visual mode: The put text replaces the selected
@@ -7916,11 +7953,15 @@ static void nv_open(cmdarg_T *cap)
     clearop(cap->oap);
     assert(cap->opcount >= 0);
     nv_diffgetput(false, (size_t)cap->opcount);
-  } else if (VIsual_active) /* switch start and end of visual */
+  } else if (VIsual_active) {
+    // switch start and end of visual/
     v_swap_corners(cap->cmdchar);
-  else
+  } else if (bt_prompt(curbuf)) {
+    clearopbeep(cap->oap);
+  } else {
     n_opencmd(cap);
   }
+}
 
 // Calculate start/end virtual columns for operating in block mode.
 static void get_op_vcol(

src/nvim/ops.c

@@ -89,6 +89,10 @@ struct block_def {
 # include "ops.c.generated.h"
 #endif
 
+// Flags for third item in "opchars".
+#define OPF_LINES  1  // operator always works on lines
+#define OPF_CHANGE 2  // operator changes text
+
 /*
  * The names of operators.
  * IMPORTANT: Index must correspond with defines in vim.h!!!
@@ -96,36 +100,36 @@ struct block_def {
  */
 static char opchars[][3] =
 {
-  { NUL,    NUL, false },    // OP_NOP
+  { NUL, NUL, 0 },                       // OP_NOP
-  { 'd',    NUL, false },    // OP_DELETE
+  { 'd', NUL, OPF_CHANGE },              // OP_DELETE
-  { 'y',    NUL, false },    // OP_YANK
+  { 'y', NUL, 0 },                       // OP_YANK
-  { 'c',    NUL, false },    // OP_CHANGE
+  { 'c', NUL, OPF_CHANGE },              // OP_CHANGE
-  { '<',    NUL, true },     // OP_LSHIFT
+  { '<', NUL, OPF_LINES | OPF_CHANGE },  // OP_LSHIFT
-  { '>',    NUL, true },     // OP_RSHIFT
+  { '>', NUL, OPF_LINES | OPF_CHANGE },  // OP_RSHIFT
-  { '!',    NUL, true },     // OP_FILTER
+  { '!', NUL, OPF_LINES | OPF_CHANGE },  // OP_FILTER
-  { 'g',    '~', false },    // OP_TILDE
+  { 'g', '~', OPF_CHANGE },              // OP_TILDE
-  { '=',    NUL, true },     // OP_INDENT
+  { '=', NUL, OPF_LINES | OPF_CHANGE },  // OP_INDENT
-  { 'g',    'q', true },     // OP_FORMAT
+  { 'g', 'q', OPF_LINES | OPF_CHANGE },  // OP_FORMAT
-  { ':',    NUL, true },     // OP_COLON
+  { ':', NUL, OPF_LINES },               // OP_COLON
-  { 'g',    'U', false },    // OP_UPPER
+  { 'g', 'U', OPF_CHANGE },              // OP_UPPER
-  { 'g',    'u', false },    // OP_LOWER
+  { 'g', 'u', OPF_CHANGE },              // OP_LOWER
-  { 'J',    NUL, true },     // DO_JOIN
+  { 'J', NUL, OPF_LINES | OPF_CHANGE },  // DO_JOIN
-  { 'g',    'J', true },     // DO_JOIN_NS
+  { 'g', 'J', OPF_LINES | OPF_CHANGE },  // DO_JOIN_NS
-  { 'g',    '?', false },    // OP_ROT13
+  { 'g', '?', OPF_CHANGE },              // OP_ROT13
-  { 'r',    NUL, false },    // OP_REPLACE
+  { 'r', NUL, OPF_CHANGE },              // OP_REPLACE
-  { 'I',    NUL, false },    // OP_INSERT
+  { 'I', NUL, OPF_CHANGE },              // OP_INSERT
-  { 'A',    NUL, false },    // OP_APPEND
+  { 'A', NUL, OPF_CHANGE },              // OP_APPEND
-  { 'z',    'f', true },     // OP_FOLD
+  { 'z', 'f', OPF_LINES },               // OP_FOLD
-  { 'z',    'o', true },     // OP_FOLDOPEN
+  { 'z', 'o', OPF_LINES },               // OP_FOLDOPEN
-  { 'z',    'O', true },     // OP_FOLDOPENREC
+  { 'z', 'O', OPF_LINES },               // OP_FOLDOPENREC
-  { 'z',    'c', true },     // OP_FOLDCLOSE
+  { 'z', 'c', OPF_LINES },               // OP_FOLDCLOSE
-  { 'z',    'C', true },     // OP_FOLDCLOSEREC
+  { 'z', 'C', OPF_LINES },               // OP_FOLDCLOSEREC
-  { 'z',    'd', true },     // OP_FOLDDEL
+  { 'z', 'd', OPF_LINES },               // OP_FOLDDEL
-  { 'z',    'D', true },     // OP_FOLDDELREC
+  { 'z', 'D', OPF_LINES },               // OP_FOLDDELREC
-  { 'g',    'w', true },     // OP_FORMAT2
+  { 'g', 'w', OPF_LINES | OPF_CHANGE },  // OP_FORMAT2
-  { 'g',    '@', false },    // OP_FUNCTION
+  { 'g', '@', OPF_CHANGE },              // OP_FUNCTION
-  { Ctrl_A, NUL, false },    // OP_NR_ADD
+  { Ctrl_A, NUL, OPF_CHANGE },           // OP_NR_ADD
-  { Ctrl_X, NUL, false },    // OP_NR_SUB
+  { Ctrl_X, NUL, OPF_CHANGE },           // OP_NR_SUB
 };
 
 /*
@@ -169,7 +173,13 @@ int get_op_type(int char1, int char2)
  */
 int op_on_lines(int op)
 {
-  return opchars[op][2];
+  return opchars[op][2] & OPF_LINES;
+}
+
+// Return TRUE if operator "op" changes text.
+int op_is_change(int op)
+{
+    return opchars[op][2] & OPF_CHANGE;
 }
 
 /*

src/nvim/option.c

@@ -299,7 +299,8 @@ static char *(p_scbopt_values[]) =    { "ver", "hor", "jump", NULL };
 static char *(p_debug_values[]) =     { "msg", "throw", "beep", NULL };
 static char *(p_ead_values[]) =       { "both", "ver", "hor", NULL };
 static char *(p_buftype_values[]) =   { "nofile", "nowrite", "quickfix",
-                                        "help", "acwrite", "terminal", NULL };
+                                        "help", "acwrite", "terminal",
+                                        "prompt", NULL };
 
 static char *(p_bufhidden_values[]) = { "hide", "unload", "delete",
                                         "wipe", NULL };
@@ -7091,6 +7092,9 @@ static int check_opt_wim(void)
  */
 bool can_bs(int what)
 {
+  if (what == BS_START && bt_prompt(curbuf)) {
+    return false;
+  }
   switch (*p_bs) {
     case '2':       return true;
     case '1':       return what != BS_START;

src/nvim/undo.c

@@ -2971,7 +2971,10 @@ static char_u *u_save_line(linenr_T lnum)
 bool bufIsChanged(buf_T *buf)
   FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
 {
-  return !bt_dontwrite(buf) && (buf->b_changed || file_ff_differs(buf, true));
+  // In a "prompt" buffer we do respect 'modified', so that we can control
+  // closing the window by setting or resetting that option.
+  return  (!bt_dontwrite(buf) || bt_prompt(buf))
+    && (buf->b_changed || file_ff_differs(buf, true));
 }
 
 // Return true if any buffer has changes.  Also buffers that are not written.

test/functional/legacy/prompt_buffer_spec.lua

@@ -0,0 +1,153 @@
+local helpers = require('test.functional.helpers')(after_each)
+local Screen = require('test.functional.ui.screen')
+local feed= helpers.feed
+local source = helpers.source
+local clear = helpers.clear
+local feed_command = helpers.feed_command
+
+describe('prompt buffer', function()
+  local screen
+
+  before_each(function()
+    clear()
+    screen = Screen.new(25, 10)
+    screen:attach()
+    source([[
+      func TextEntered(text)
+        if a:text == "exit"
+          set nomodified
+          stopinsert
+          close
+        else
+          call append(line("$") - 1, 'Command: "' . a:text . '"')
+          set nomodfied
+          call timer_start(20, {id -> TimerFunc(a:text)})
+        endif
+      endfunc
+
+      func TimerFunc(text)
+        call append(line("$") - 1, 'Result: "' . a:text .'"')
+      endfunc
+    ]])
+    feed_command("set noshowmode | set laststatus=0")
+    feed_command("call setline(1, 'other buffer')")
+    feed_command("new")
+    feed_command("set buftype=prompt")
+    feed_command("call prompt_setcallback(bufnr(''), function('TextEntered'))")
+  end)
+
+  after_each(function()
+    screen:detach()
+  end)
+
+  it('works', function()
+    screen:expect([[
+      ^                         |
+      ~                        |
+      ~                        |
+      ~                        |
+      [Prompt]                 |
+      other buffer             |
+      ~                        |
+      ~                        |
+      ~                        |
+                               |
+    ]])
+    feed("i")
+    feed("hello\n")
+    screen:expect([[
+      % hello                  |
+      Command: "hello"         |
+      Result: "hello"          |
+      % ^                       |
+      [Prompt] [+]             |
+      other buffer             |
+      ~                        |
+      ~                        |
+      ~                        |
+                               |
+    ]])
+    feed("exit\n")
+    screen:expect([[
+      ^other buffer             |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+                               |
+    ]])
+  end)
+
+  it('editing', function()
+    screen:expect([[
+      ^                         |
+      ~                        |
+      ~                        |
+      ~                        |
+      [Prompt]                 |
+      other buffer             |
+      ~                        |
+      ~                        |
+      ~                        |
+                               |
+    ]])
+    feed("i")
+    feed("hello<BS><BS>")
+    screen:expect([[
+      % hel^                    |
+      ~                        |
+      ~                        |
+      ~                        |
+      [Prompt] [+]             |
+      other buffer             |
+      ~                        |
+      ~                        |
+      ~                        |
+                               |
+    ]])
+    feed("<Left><Left><Left><BS>-")
+    screen:expect([[
+      % -^hel                   |
+      ~                        |
+      ~                        |
+      ~                        |
+      [Prompt] [+]             |
+      other buffer             |
+      ~                        |
+      ~                        |
+      ~                        |
+                               |
+    ]])
+    feed("<End>x")
+    screen:expect([[
+      % -helx^                  |
+      ~                        |
+      ~                        |
+      ~                        |
+      [Prompt] [+]             |
+      other buffer             |
+      ~                        |
+      ~                        |
+      ~                        |
+                               |
+    ]])
+    feed("<C-U>exit\n")
+    screen:expect([[
+      ^other buffer             |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+      ~                        |
+                               |
+    ]])
+  end)
+
+end)