vim-patch:9.1.0147: Cannot keep a buffer focused in a window

Problem:  Cannot keep a buffer focused in a window
          (Amit Levy)
Solution: Add the 'winfixbuf' window-local option
          (Colin Kennedy)

fixes:  vim/vim#6445
closes: vim/vim#13903

vim/vim@2157035

N/A patch:
vim-patch:58f1e5c0893a

runtime/doc/message.txt

@@ -114,6 +114,13 @@ wiped out a buffer which contains a mark or is referenced in another way.
 You cannot have two buffers with exactly the same name.  This includes the
 path leading to the file.
 
+							*E1513* >
+  Cannot edit buffer. 'winfixbuf' is enabled
+
+If a window has 'winfixbuf' enabled, you cannot change that window's current
+buffer. You need to set 'nowinfixbuf' before continuing. You may use [!] to
+force the window to switch buffers, if your command supports it.
+
 							*E72*  >
   Close error on swap file
 

runtime/doc/news.txt

@@ -160,6 +160,8 @@ The following new APIs and features were added.
   • 'breakindent' performance is significantly improved for wrapped lines.
   • Cursor movement, insertion with [count] and |screenpos()| are now faster.
 
+• |'winfixbuf'| keeps a window focused onto a specific buffer
+
 • |vim.iter()| provides a generic iterator interface for tables and Lua
   iterators |for-in|.
 

runtime/doc/options.txt

@@ -6271,6 +6271,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 			"split" when both are present.
 	   uselast	If included, jump to the previously used window when
 			jumping to errors with |quickfix| commands.
+	If a window has 'winfixbuf' enabled, 'switchbuf' is currently not
+	applied to the split window.
 
 						*'synmaxcol'* *'smc'*
 'synmaxcol' 'smc'	number	(default 3000)
@@ -7170,6 +7172,15 @@ A jump table for the options with a short description can be found at |Q_op|.
 	Note: Do not confuse this with the height of the Vim window, use
 	'lines' for that.
 
+			*'winfixbuf'* *'wfb'* *'nowinfixbuf'* *'nowfb'*
+'winfixbuf' 'wfb'	boolean	(default off)
+			local to window
+	If enabled, the buffer and any window that displays it are paired.
+	For example, attempting to change the buffer with |:edit| will fail.
+	Other commands which change a window's buffer such as |:cnext| will
+	also skip any window with 'winfixbuf' enabled. However if a command
+	has an "!" option, a window can be forced to switch buffers.
+
 			*'winfixheight'* *'wfh'* *'nowinfixheight'* *'nowfh'*
 'winfixheight' 'wfh'	boolean	(default off)
 			local to window  |local-noglobal|

runtime/doc/quickref.txt

@@ -939,6 +939,7 @@ Short explanation of each option:		*option-list*
 'wildoptions'	  'wop'     specifies how command line completion is done
 'winaltkeys'	  'wak'     when the windows system handles ALT keys
 'window'	  'wi'	    nr of lines to scroll for CTRL-F and CTRL-B
+'winfixbuf'	  'wfb'     keep window focused on a single buffer
 'winfixheight'	  'wfh'     keep window height when opening/closing windows
 'winfixwidth'	  'wfw'     keep window width when opening/closing windows
 'winheight'	  'wh'	    minimum number of lines for the current window

runtime/doc/tagsrch.txt

@@ -402,17 +402,22 @@ If the tag is in the current file this will always work.  Otherwise the
 performed actions depend on whether the current file was changed, whether a !
 is added to the command and on the 'autowrite' option:
 
-  tag in       file	   autowrite			~
-current file  changed	!   option	  action	~
- ---------------------------------------------------------------------------
-    yes		 x	x     x	  goto tag
-    no		 no	x     x	  read other file, goto tag
-    no		yes    yes    x   abandon current file, read other file, goto
-				  tag
-    no		yes	no    on  write current file, read other file, goto
-				  tag
-    no		yes	no   off  fail
- ---------------------------------------------------------------------------
+  tag in       file	                autowrite			~
+current file  changed	!   winfixbuf   option	      action	~
+ -----------------------------------------------------------------------------
+    yes		x	x      no         x         goto tag
+    no		no	x      no         x         read other file, goto tag
+    no		yes	yes    no         x         abandon current file,
+						    read other file, goto tag
+    no		yes	no     no         on        write current file,
+						    read other file, goto tag
+    no		yes	no     no         off       fail
+    yes		x	yes    x          x         goto tag
+    no		no	no     yes        x         fail
+    no		yes	no     yes        x         fail
+    no		yes	no     yes        on        fail
+    no		yes	no     yes        off       fail
+ -----------------------------------------------------------------------------
 
 - If the tag is in the current file, the command will always work.
 - If the tag is in another file and the current file was not changed, the
@@ -428,6 +433,8 @@ current file  changed	!   option	  action	~
   the changes, use the ":w" command and then use ":tag" without an argument.
   This works because the tag is put on the stack anyway.  If you want to lose
   the changes you can use the ":tag!" command.
+- If the tag is in another file and the window includes 'winfixbuf', the
+  command will fail. If the tag is in the same file then it may succeed.
 
 							*tag-security*
 Note that Vim forbids some commands, for security reasons.  This works like

runtime/optwin.vim

@@ -444,6 +444,7 @@ if has("statusline")
   call <SID>AddOption("statusline", gettext("alternate format to be used for a status line"))
   call <SID>OptionG("stl", &stl)
 endif
+call append("$", "\t" .. s:local_to_window)
 call <SID>AddOption("equalalways", gettext("make all windows the same size when adding/removing windows"))
 call <SID>BinOptionG("ea", &ea)
 call <SID>AddOption("eadirection", gettext("in which direction 'equalalways' works: \"ver\", \"hor\" or \"both\""))
@@ -452,6 +453,8 @@ call <SID>AddOption("winheight", gettext("minimal number of lines used for the c
 call append("$", " \tset wh=" . &wh)
 call <SID>AddOption("winminheight", gettext("minimal number of lines used for any window"))
 call append("$", " \tset wmh=" . &wmh)
+call <SID>AddOption("winfixbuf", gettext("keep window focused on a single buffer"))
+call <SID>OptionG("wfb", &wfb)
 call <SID>AddOption("winfixheight", gettext("keep the height of the window"))
 call append("$", "\t" .. s:local_to_window)
 call <SID>BinOptionL("wfh")

src/nvim/api/vim.c

@@ -876,6 +876,11 @@ void nvim_set_current_buf(Buffer buffer, Error *err)
     return;
   }
 
+  if (curwin->w_p_wfb) {
+    api_set_error(err, kErrorTypeException, "%s", e_winfixbuf_cannot_go_to_buffer);
+    return;
+  }
+
   try_start();
   int result = do_buffer(DOBUF_GOTO, DOBUF_FIRST, FORWARD, buf->b_fnum, 0);
   if (!try_end(err) && result == FAIL) {

src/nvim/api/window.c

@@ -61,6 +61,12 @@ void nvim_win_set_buf(Window window, Buffer buffer, Error *err)
   if (!win || !buf) {
     return;
   }
+
+  if (win->w_p_wfb) {
+    api_set_error(err, kErrorTypeException, "%s", e_winfixbuf_cannot_go_to_buffer);
+    return;
+  }
+
   if (win == cmdwin_win || win == cmdwin_old_curwin || buf == cmdwin_buf) {
     api_set_error(err, kErrorTypeException, "%s", e_cmdwin);
     return;

src/nvim/arglist.c

@@ -623,6 +623,8 @@ void ex_argument(exarg_T *eap)
 /// Edit file "argn" of the argument lists.
 void do_argfile(exarg_T *eap, int argn)
 {
+  bool is_split_cmd = *eap->cmd == 's';
+
   int old_arg_idx = curwin->w_arg_idx;
 
   if (argn < 0 || argn >= ARGCOUNT) {
@@ -637,10 +639,16 @@ void do_argfile(exarg_T *eap, int argn)
     return;
   }
 
+  if (!is_split_cmd
+      && (&ARGLIST[argn])->ae_fnum != curbuf->b_fnum
+      && !check_can_set_curbuf_forceit(eap->forceit)) {
+    return;
+  }
+
   setpcmark();
 
   // split window or create new tab page first
-  if (*eap->cmd == 's' || cmdmod.cmod_tab != 0) {
+  if (is_split_cmd || cmdmod.cmod_tab != 0) {
     if (win_split(0, 0) == FAIL) {
       return;
     }

src/nvim/buffer.c

@@ -1305,6 +1305,12 @@ int do_buffer(int action, int start, int dir, int count, int forceit)
     }
     return FAIL;
   }
+
+  if (action == DOBUF_GOTO && buf != curbuf && !check_can_set_curbuf_forceit(forceit)) {
+    // disallow navigating to another buffer when 'winfixbuf' is applied
+    return FAIL;
+  }
+
   if ((action == DOBUF_GOTO || action == DOBUF_SPLIT) && (buf->b_flags & BF_DUMMY)) {
     // disallow navigating to the dummy buffer
     semsg(_(e_nobufnr), count);

src/nvim/buffer_defs.h

@@ -139,6 +139,8 @@ typedef struct {
 #define w_ve_flags w_onebuf_opt.wo_ve_flags  // flags for 'virtualedit'
   OptInt wo_nuw;
 #define w_p_nuw w_onebuf_opt.wo_nuw    // 'numberwidth'
+  int wo_wfb;
+#define w_p_wfb w_onebuf_opt.wo_wfb    // 'winfixbuf'
   int wo_wfh;
 #define w_p_wfh w_onebuf_opt.wo_wfh    // 'winfixheight'
   int wo_wfw;

src/nvim/ex_cmds.c

@@ -2008,6 +2008,10 @@ static int check_readonly(int *forceit, buf_T *buf)
 ///           GETFILE_OPEN_OTHER for successfully opening another file.
 int getfile(int fnum, char *ffname_arg, char *sfname_arg, bool setpm, linenr_T lnum, bool forceit)
 {
+  if (!check_can_set_curbuf_forceit(forceit)) {
+    return GETFILE_ERROR;
+  }
+
   char *ffname = ffname_arg;
   char *sfname = sfname_arg;
   bool other;

src/nvim/ex_cmds.lua

@@ -812,7 +812,7 @@ module.cmds = {
   },
   {
     command = 'drop',
-    flags = bit.bor(FILES, CMDARG, NEEDARG, ARGOPT, TRLBAR),
+    flags = bit.bor(BANG, FILES, CMDARG, NEEDARG, ARGOPT, TRLBAR),
     addr_type = 'ADDR_NONE',
     func = 'ex_drop',
   },

src/nvim/ex_cmds2.c

@@ -444,6 +444,27 @@ int buf_write_all(buf_T *buf, bool forceit)
 /// ":argdo", ":windo", ":bufdo", ":tabdo", ":cdo", ":ldo", ":cfdo" and ":lfdo"
 void ex_listdo(exarg_T *eap)
 {
+  if (curwin->w_p_wfb) {
+    if ((eap->cmdidx == CMD_ldo || eap->cmdidx == CMD_lfdo) && !eap->forceit) {
+      // Disallow :ldo if 'winfixbuf' is applied
+      semsg("%s", e_winfixbuf_cannot_go_to_buffer);
+      return;
+    }
+
+    if (win_valid(prevwin)) {
+      // Change the current window to another because 'winfixbuf' is enabled
+      curwin = prevwin;
+    } else {
+      // Split the window, which will be 'nowinfixbuf', and set curwin to that
+      exarg_T new_eap = {
+        .cmdidx = CMD_split,
+        .cmd = "split",
+        .arg = "",
+      };
+      ex_splitview(&new_eap);
+    }
+  }
+
   char *save_ei = NULL;
 
   // Temporarily override SHM_OVER and SHM_OVERALL to avoid that file

src/nvim/ex_docmd.c

@@ -5334,6 +5334,10 @@ static void ex_resize(exarg_T *eap)
 /// ":find [+command] <file>" command.
 static void ex_find(exarg_T *eap)
 {
+  if (!check_can_set_curbuf_forceit(eap->forceit)) {
+    return;
+  }
+
   char *file_to_find = NULL;
   char *search_ctx = NULL;
   char *fname = find_file_in_path(eap->arg, strlen(eap->arg),
@@ -5364,6 +5368,14 @@ static void ex_find(exarg_T *eap)
 /// ":edit", ":badd", ":balt", ":visual".
 static void ex_edit(exarg_T *eap)
 {
+  // Exclude commands which keep the window's current buffer
+  if (eap->cmdidx != CMD_badd
+      && eap->cmdidx != CMD_balt
+      // All other commands must obey 'winfixbuf' / ! rules
+      && !check_can_set_curbuf_forceit(eap->forceit)) {
+    return;
+  }
+
   do_exedit(eap, NULL);
 }
 
@@ -6670,7 +6682,7 @@ static void ex_checkpath(exarg_T *eap)
 {
   find_pattern_in_path(NULL, 0, 0, false, false, CHECK_PATH, 1,
                        eap->forceit ? ACTION_SHOW_ALL : ACTION_SHOW,
-                       1, (linenr_T)MAXLNUM);
+                       1, (linenr_T)MAXLNUM, eap->forceit);
 }
 
 /// ":psearch"
@@ -6729,7 +6741,7 @@ static void ex_findpat(exarg_T *eap)
   if (!eap->skip) {
     find_pattern_in_path(eap->arg, 0, strlen(eap->arg), whole, !eap->forceit,
                          *eap->cmd == 'd' ? FIND_DEFINE : FIND_ANY,
-                         n, action, eap->line1, eap->line2);
+                         n, action, eap->line1, eap->line2, eap->forceit);
   }
 }
 

src/nvim/globals.h

@@ -971,6 +971,9 @@ EXTERN const char e_val_too_large[] INIT(= N_("E1510: Value too large: %s"));
 EXTERN const char e_undobang_cannot_redo_or_move_branch[]
 INIT(= N_("E5767: Cannot use :undo! to redo or move to a different undo branch"));
 
+EXTERN const char e_winfixbuf_cannot_go_to_buffer[]
+INIT(= N_("E1513: Cannot edit buffer. 'winfixbuf' is enabled"));
+
 EXTERN const char e_trustfile[] INIT(= N_("E5570: Cannot update trust file: %s"));
 
 EXTERN const char e_unknown_option2[] INIT(= N_("E355: Unknown option: %s"));

src/nvim/insexpand.c

@@ -3027,7 +3027,7 @@ static void get_next_include_file_completion(int compl_type)
                        ((compl_type == CTRL_X_PATH_DEFINES
                          && !(compl_cont_status & CONT_SOL))
                         ? FIND_DEFINE : FIND_ANY),
-                       1, ACTION_EXPAND, 1, MAXLNUM);
+                       1, ACTION_EXPAND, 1, MAXLNUM, false);
 }
 
 /// Get the next set of words matching "compl_pattern" in dictionary or

src/nvim/normal.c

@@ -3896,6 +3896,10 @@ static void nv_gotofile(cmdarg_T *cap)
     return;
   }
 
+  if (!check_can_set_curbuf_disabled()) {
+    return;
+  }
+
   char *ptr = grab_file_name(cap->count1, &lnum);
 
   if (ptr != NULL) {
@@ -4232,7 +4236,8 @@ static void nv_brackets(cmdarg_T *cap)
                            (cap->cmdchar == ']'
                             ? curwin->w_cursor.lnum + 1
                             : 1),
-                           MAXLNUM);
+                           MAXLNUM,
+                           false);
       xfree(ptr);
       curwin->w_set_curswant = true;
     }

src/nvim/option.c

@@ -4629,6 +4629,8 @@ void *get_varp_from(vimoption_T *p, buf_T *buf, win_T *win)
     return &(win->w_p_rnu);
   case PV_NUW:
     return &(win->w_p_nuw);
+  case PV_WFB:
+    return &(win->w_p_wfb);
   case PV_WFH:
     return &(win->w_p_wfh);
   case PV_WFW:

src/nvim/options.lua

@@ -8406,6 +8406,8 @@ return {
         		"split" when both are present.
            uselast	If included, jump to the previously used window when
         		jumping to errors with |quickfix| commands.
+        If a window has 'winfixbuf' enabled, 'switchbuf' is currently not
+        applied to the split window.
       ]=],
       expand_cb = 'expand_set_switchbuf',
       full_name = 'switchbuf',
@@ -9816,6 +9818,23 @@ return {
       type = 'number',
       varname = 'p_window',
     },
+    {
+      abbreviation = 'wfb',
+      defaults = { if_true = false },
+      desc = [=[
+        If enabled, the buffer and any window that displays it are paired.
+        For example, attempting to change the buffer with |:edit| will fail.
+        Other commands which change a window's buffer such as |:cnext| will
+        also skip any window with 'winfixbuf' enabled. However if a command
+        has an "!" option, a window can be forced to switch buffers.
+      ]=],
+      full_name = 'winfixbuf',
+      pv_name = 'p_wfb',
+      redraw = { 'current_window' },
+      scope = { 'window' },
+      short_desc = N_('pin a window to a specific buffer'),
+      type = 'boolean',
+    },
     {
       abbreviation = 'wfh',
       defaults = { if_true = false },