refactor(window): lastwin_nofloating takes tp

src/nvim/api/win_config.c

@@ -680,17 +680,9 @@ static bool win_config_float_tp(win_T *win, const Dict(win_config) *config,
     // Check again, in case autocommands above moved windows to the same tabpage.
     if (win_tp != parent_tp) {
       win_remove(win, win_tp == curtab ? NULL : win_tp);
-      win_T *after;
-      if (parent_tp == curtab) {
-        after = lastwin_nofloating();
-      } else {
-        after = parent_tp->tp_lastwin;
-        while (after->w_floating) {
-          after = after->w_prev;
-        }
-      }
+      tabpage_T *append_tp = parent_tp == curtab ? NULL : parent_tp;
+      win_append(lastwin_nofloating(append_tp), win, append_tp);
 
-      win_append(after, win, parent_tp == curtab ? NULL : parent_tp);
       // If `win` was the curwin of its old tabpage, select a new curwin for it.
       if (win_tp != curtab && win_tp->tp_curwin == win) {
         win_tp->tp_curwin = win_float_find_altwin(win, win_tp);

src/nvim/arglist.c

@@ -1116,7 +1116,7 @@ static void do_arg_all(int count, int forceit, int keep_tabs)
   last_curwin = curwin;
   last_curtab = curtab;
   // lastwin may be aucmd_win
-  win_enter(lastwin_nofloating(), false);
+  win_enter(lastwin_nofloating(NULL), false);
 
   // Open up to "count" windows.
   arg_all_open_windows(&aall, count);

src/nvim/buffer.c

@@ -3692,7 +3692,7 @@ void ex_buffer_all(exarg_T *eap)
   // Don't execute Win/Buf Enter/Leave autocommands here.
   autocmd_no_enter++;
   // lastwin may be aucmd_win
-  win_enter(lastwin_nofloating(), false);
+  win_enter(lastwin_nofloating(NULL), false);
   autocmd_no_leave++;
   for (buf_T *buf = firstbuf; buf != NULL && open_wins < count; buf = buf->b_next) {
     // Check if this buffer needs a window

src/nvim/ex_getln.c

@@ -4062,7 +4062,7 @@ void compute_cmdrow(void)
   if (exmode_active || msg_scrolled != 0) {
     cmdline_row = Rows - 1;
   } else {
-    win_T *wp = lastwin_nofloating();
+    win_T *wp = lastwin_nofloating(NULL);
     cmdline_row = wp->w_winrow + wp->w_height
                   + wp->w_hsep_height + wp->w_status_height + global_stl_height();
   }

src/nvim/statusline.c

@@ -440,7 +440,7 @@ void win_redr_winbar(win_T *wp)
 void redraw_ruler(void)
 {
   static int did_ruler_col = -1;
-  win_T *wp = curwin->w_status_height == 0 ? curwin : lastwin_nofloating();
+  win_T *wp = curwin->w_status_height == 0 ? curwin : lastwin_nofloating(NULL);
   bool is_stl_global = global_stl_height() > 0;
 
   // Check if ruler should be drawn, clear if it was drawn before.

src/nvim/window.c

@@ -505,7 +505,7 @@ newwindow:
   // cursor to bottom-right window
   case 'b':
   case Ctrl_B:
-    win_goto(lastwin_nofloating());
+    win_goto(lastwin_nofloating(NULL));
     break;
 
   // cursor to last accessed (previous) window
@@ -1158,7 +1158,7 @@ win_T *win_split_ins(int size, int flags, win_T *new_wp, int dir, frame_T *to_fl
     oldwin = firstwin;
   } else if (flags & WSP_BOT || curwin->w_floating) {
     // can't split float, use last nonfloating window instead
-    oldwin = lastwin_nofloating();
+    oldwin = lastwin_nofloating(NULL);
   } else {
     oldwin = curwin;
   }
@@ -4800,7 +4800,7 @@ static void tabpage_check_windows(tabpage_T *old_curtab)
     if (wp->w_floating) {
       if (wp->w_config.external) {
         win_remove(wp, old_curtab);
-        win_append(lastwin_nofloating(), wp, NULL);
+        win_append(lastwin_nofloating(NULL), wp, NULL);
       } else {
         ui_comp_remove_grid(&wp->w_grid_alloc);
       }
@@ -6237,7 +6237,7 @@ static void frame_setheight(frame_T *curfrp, int height)
       if (curfrp->fr_width != Columns) {
         room_cmdline = 0;
       } else {
-        win_T *wp = lastwin_nofloating();
+        win_T *wp = lastwin_nofloating(NULL);
         room_cmdline = Rows - (int)p_ch - global_stl_height()
                        - (wp->w_winrow + wp->w_height + wp->w_hsep_height + wp->w_status_height);
         room_cmdline = MAX(room_cmdline, 0);
@@ -7051,7 +7051,7 @@ void command_height(void)
   int old_p_ch = (int)curtab->tp_ch_used;
 
   // Find bottom frame with width of screen.
-  frame_T *frp = lastwin_nofloating()->w_frame;
+  frame_T *frp = lastwin_nofloating(NULL)->w_frame;
   while (frp->fr_width != Columns && frp->fr_parent != NULL) {
     frp = frp->fr_parent;
   }
@@ -7804,9 +7804,11 @@ void win_ui_flush(bool validate)
   msg_ui_flush();
 }
 
-win_T *lastwin_nofloating(void)
+/// @return last non-floating window in `tp`, or NULL for current tabpage.
+win_T *lastwin_nofloating(tabpage_T *tp)
 {
-  win_T *res = lastwin;
+  assert(tp != curtab || !tp);
+  win_T *res = tp ? tp->tp_lastwin : lastwin;
   while (res->w_floating) {
     res = res->w_prev;
   }

src/nvim/winfloat.c

@@ -46,7 +46,7 @@ win_T *win_new_float(win_T *wp, bool last, WinConfig fconfig, Error *err)
 {
   if (wp == NULL) {
     tabpage_T *tp = NULL;
-    win_T *tp_last = last ? lastwin : lastwin_nofloating();
+    win_T *tp_last = last ? lastwin : lastwin_nofloating(NULL);
     if (fconfig.window != 0) {
       assert(!last);
       win_T *parent_wp = find_window_by_handle(fconfig.window, err);
@@ -57,10 +57,7 @@ win_T *win_new_float(win_T *wp, bool last, WinConfig fconfig, Error *err)
       if (!tp) {
         return NULL;
       }
-      tp_last = tp == curtab ? lastwin : tp->tp_lastwin;
-      while (tp_last->w_floating && tp_last->w_prev) {
-        tp_last = tp_last->w_prev;
-      }
+      tp_last = lastwin_nofloating(tp == curtab ? NULL : tp);
     }
     wp = win_alloc(tp_last, false);
     win_init(wp, curwin, 0);
@@ -77,7 +74,7 @@ win_T *win_new_float(win_T *wp, bool last, WinConfig fconfig, Error *err)
   } else {
     assert(!last);
     assert(!wp->w_floating);
-    if (firstwin == wp && lastwin_nofloating() == wp) {
+    if (firstwin == wp && lastwin_nofloating(NULL) == wp) {
       // last non-float
       api_set_error(err, kErrorTypeException,
                     "Cannot change last window into float");
@@ -105,7 +102,7 @@ win_T *win_new_float(win_T *wp, bool last, WinConfig fconfig, Error *err)
     XFREE_CLEAR(wp->w_frame);
     win_comp_pos();  // recompute window positions
     win_remove(wp, NULL);
-    win_append(lastwin_nofloating(), wp, NULL);
+    win_append(lastwin_nofloating(NULL), wp, NULL);
   }
   wp->w_floating = true;
   wp->w_status_height = wp->w_p_stl && *wp->w_p_stl != NUL