vim-patch:9.1.0047: issues with temp curwin/buf while cmdwin is open

Problem:  Things that temporarily change/restore curwin/buf (e.g:
          win_execute, some autocmds) may break assumptions that
          curwin/buf is the cmdwin when "cmdwin_type != 0", causing
          issues.

Solution: Expose the cmdwin's real win/buf and check that instead. Also
          try to ensure these variables are NULL if "cmdwin_type == 0",
          allowing them to be used directly in most cases without
          checking cmdwin_type. (Sean Dewar)

Reset and save `cmdwin_old_curwin` in a similar fashion.
Apply suitable changes for API functions and add Lua tests.

https://github.com/vim/vim/commit/988f74311c26ea9917e84fbae608de226dba7e5f

12 files changed, 37 insertions, 13 deletions

diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index eea9b54a5c..4bd8f551db 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1022,7 +1022,7 @@ Integer nvim_open_term(Buffer buffer, Dict(open_term) *opts, Error *err)
     return 0;
   }
 
-  if (cmdwin_type != 0 && buf == curbuf) {
+  if (buf == cmdwin_buf) {
     api_set_error(err, kErrorTypeException, "%s", e_cmdwin);
     return 0;
   }
diff --git a/src/nvim/api/win_config.c b/src/nvim/api/win_config.c
index ccbd341fd2..6df86683c1 100644
--- a/src/nvim/api/win_config.c
+++ b/src/nvim/api/win_config.c
@@ -181,7 +181,7 @@ Window nvim_open_win(Buffer buffer, Boolean enter, Dict(float_config) *config, E
   if (!buf) {
     return 0;
   }
-  if (cmdwin_type != 0 && (enter || buf == curbuf)) {
+  if ((cmdwin_type != 0 && enter) || buf == cmdwin_buf) {
     api_set_error(err, kErrorTypeException, "%s", e_cmdwin);
     return 0;
   }
diff --git a/src/nvim/api/window.c b/src/nvim/api/window.c
index 00126c64f1..4ac7e47832 100644
--- a/src/nvim/api/window.c
+++ b/src/nvim/api/window.c
@@ -61,7 +61,7 @@ void nvim_win_set_buf(Window window, Buffer buffer, Error *err)
   if (!win || !buf) {
     return;
   }
-  if (cmdwin_type != 0 && (win == curwin || win == cmdwin_old_curwin || buf == curbuf)) {
+  if (win == cmdwin_win || win == cmdwin_old_curwin || buf == cmdwin_buf) {
     api_set_error(err, kErrorTypeException, "%s", e_cmdwin);
     return;
   }
diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index 0dd8d6398b..0b88c307c7 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -1219,7 +1219,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int col_rows, s
     statuscol.draw = true;
     statuscol.sattrs = wlv.sattrs;
     statuscol.foldinfo = foldinfo;
-    statuscol.width = win_col_off(wp) - (cmdwin_type != 0 && wp == curwin);
+    statuscol.width = win_col_off(wp) - (wp == cmdwin_win);
     statuscol.use_cul = use_cursor_line_highlight(wp, lnum);
     statuscol.sign_cul_id = statuscol.use_cul ? sign_cul_attr : 0;
     statuscol.num_attr = sign_num_attr > 0 ? syn_id2attr(sign_num_attr) : 0;
@@ -1511,7 +1511,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int col_rows, s
 
       assert(wlv.off == 0);
 
-      if (cmdwin_type != 0 && wp == curwin) {
+      if (wp == cmdwin_win) {
         // Draw the cmdline character.
         draw_col_fill(&wlv, schar_from_ascii(cmdwin_type), 1, win_hl_attr(wp, HLF_AT));
       }
diff --git a/src/nvim/eval/window.c b/src/nvim/eval/window.c
index b621cec5f4..b8aa0c9641 100644
--- a/src/nvim/eval/window.c
+++ b/src/nvim/eval/window.c
@@ -755,7 +755,7 @@ void f_win_gettype(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     rettv->vval.v_string = xstrdup("preview");
   } else if (wp->w_floating) {
     rettv->vval.v_string = xstrdup("popup");
-  } else if (wp == curwin && cmdwin_type != 0) {
+  } else if (wp == cmdwin_win) {
     rettv->vval.v_string = xstrdup("command");
   } else if (bt_quickfix(wp->w_buffer)) {
     rettv->vval.v_string = xstrdup((wp->w_llist_ref != NULL ? "loclist" : "quickfix"));
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 373ff8feda..41d8e5d914 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -2305,10 +2305,19 @@ int do_ecmd(int fnum, char *ffname, char *sfname, exarg_T *eap, linenr_T newlnum
     // If the current buffer was empty and has no file name, curbuf
     // is returned by buflist_new(), nothing to do here.
     if (buf != curbuf) {
+      // Should only be possible to get here if the cmdwin is closed, or
+      // if it's opening and its buffer hasn't been set yet (the new
+      // buffer is for it).
+      assert(cmdwin_buf == NULL);
+
       const int save_cmdwin_type = cmdwin_type;
+      win_T *const save_cmdwin_win = cmdwin_win;
+      win_T *const save_cmdwin_old_curwin = cmdwin_old_curwin;
 
       // BufLeave applies to the old buffer.
       cmdwin_type = 0;
+      cmdwin_win = NULL;
+      cmdwin_old_curwin = NULL;
 
       // Be careful: The autocommands may delete any buffer and change
       // the current buffer.
@@ -2324,7 +2333,11 @@ int do_ecmd(int fnum, char *ffname, char *sfname, exarg_T *eap, linenr_T newlnum
       const bufref_T save_au_new_curbuf = au_new_curbuf;
       set_bufref(&au_new_curbuf, buf);
       apply_autocmds(EVENT_BUFLEAVE, NULL, NULL, false, curbuf);
+
       cmdwin_type = save_cmdwin_type;
+      cmdwin_win = save_cmdwin_win;
+      cmdwin_old_curwin = save_cmdwin_old_curwin;
+
       if (!bufref_valid(&au_new_curbuf)) {
         // New buffer has been deleted.
         delbuf_msg(new_name);  // Frees new_name.
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 2c5c291216..f49652fc92 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -4326,9 +4326,10 @@ static int open_cmdwin(void)
   // Don't let quitting the More prompt make this fail.
   got_int = false;
 
-  // Set "cmdwin_type" before any autocommands may mess things up.
+  // Set "cmdwin_..." variables before any autocommands may mess things up.
   cmdwin_type = get_cmdline_type();
   cmdwin_level = ccline.level;
+  cmdwin_win = curwin;
   cmdwin_old_curwin = old_curwin;
 
   // Create empty command-line buffer.
@@ -4337,9 +4338,12 @@ static int open_cmdwin(void)
     win_close(curwin, true, false);
     ga_clear(&winsizes);
     cmdwin_type = 0;
+    cmdwin_win = NULL;
     cmdwin_old_curwin = NULL;
     return Ctrl_C;
   }
+  cmdwin_buf = curbuf;
+
   // Command-line buffer has bufhidden=wipe, unlike a true "scratch" buffer.
   set_option_value_give_err(kOptBufhidden, STATIC_CSTR_AS_OPTVAL("wipe"), OPT_LOCAL);
   curbuf->b_p_ma = true;
@@ -4434,6 +4438,8 @@ static int open_cmdwin(void)
 
   cmdwin_type = 0;
   cmdwin_level = 0;
+  cmdwin_buf = NULL;
+  cmdwin_win = NULL;
   cmdwin_old_curwin = NULL;
 
   exmode_active = save_exmode;
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index f0cc9dba74..a06e9fe542 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -752,6 +752,8 @@ EXTERN bool km_startsel INIT( = false);
 EXTERN int cmdwin_type INIT( = 0);    ///< type of cmdline window or 0
 EXTERN int cmdwin_result INIT( = 0);  ///< result of cmdline window or 0
 EXTERN int cmdwin_level INIT( = 0);   ///< cmdline recursion level
+EXTERN buf_T *cmdwin_buf INIT( = NULL);  ///< buffer of cmdline window or NULL
+EXTERN win_T *cmdwin_win INIT( = NULL);  ///< window of cmdline window or NULL
 EXTERN win_T *cmdwin_old_curwin INIT( = NULL);  ///< curwin before opening cmdline window or NULL
 
 EXTERN char no_lines_msg[] INIT( = N_("--No lines in buffer--"));
diff --git a/src/nvim/mouse.c b/src/nvim/mouse.c
index b3f651296f..c0a928416d 100644
--- a/src/nvim/mouse.c
+++ b/src/nvim/mouse.c
@@ -1326,18 +1326,18 @@ retnomove:
                 && !sep_line_offset
                 && (wp->w_p_rl
                     ? col < wp->w_width_inner - fdc
-                    : col >= fdc + (cmdwin_type == 0 && wp == curwin ? 0 : 1))
+                    : col >= fdc + (wp != cmdwin_win ? 0 : 1))
                 && (flags & MOUSE_MAY_STOP_VIS)))) {
       end_visual_mode();
       redraw_curbuf_later(UPD_INVERTED);  // delete the inversion
     }
-    if (cmdwin_type != 0 && wp != curwin) {
+    if (cmdwin_type != 0 && wp != cmdwin_win) {
       // A click outside the command-line window: Use modeless
       // selection if possible.  Allow dragging the status lines.
       sep_line_offset = 0;
       row = 0;
       col += wp->w_wincol;
-      wp = curwin;
+      wp = cmdwin_win;
     }
     // Only change window focus when not clicking on or dragging the
     // status line.  Do change focus when releasing the mouse button
diff --git a/src/nvim/move.c b/src/nvim/move.c
index a7380577c4..a303d1757f 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -760,7 +760,7 @@ int win_col_off(win_T *wp)
 {
   return ((wp->w_p_nu || wp->w_p_rnu || *wp->w_p_stc != NUL)
           ? (number_width(wp) + (*wp->w_p_stc == NUL)) : 0)
-         + ((cmdwin_type == 0 || wp != curwin) ? 0 : 1)
+         + ((wp != cmdwin_win) ? 0 : 1)
          + win_fdccol_count(wp) + (wp->w_scwidth * SIGN_WIDTH);
 }
 
diff --git a/src/nvim/textformat.c b/src/nvim/textformat.c
index 64cccf5f3f..bfe3ed5972 100644
--- a/src/nvim/textformat.c
+++ b/src/nvim/textformat.c
@@ -763,7 +763,7 @@ int comp_textwidth(bool ff)
     // The width is the window width minus 'wrapmargin' minus all the
     // things that add to the margin.
     textwidth = curwin->w_width_inner - (int)curbuf->b_p_wm;
-    if (cmdwin_type != 0) {
+    if (curbuf == cmdwin_buf) {
       textwidth -= 1;
     }
     textwidth -= win_fdccol_count(curwin);
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 23779d1e7b..112ac8bf3b 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -2485,7 +2485,7 @@ bool can_close_in_cmdwin(win_T *win, Error *err)
   FUNC_ATTR_NONNULL_ALL
 {
   if (cmdwin_type != 0) {
-    if (win == curwin) {
+    if (win == cmdwin_win) {
       cmdwin_result = Ctrl_C;
       return false;
     } else if (win == cmdwin_old_curwin) {
@@ -3030,6 +3030,9 @@ void win_free_all(void)
 {
   // avoid an error for switching tabpage with the cmdline window open
   cmdwin_type = 0;
+  cmdwin_buf = NULL;
+  cmdwin_win = NULL;
+  cmdwin_old_curwin = NULL;
 
   while (first_tabpage->tp_next != NULL) {
     tabpage_close(true);