revert: "fix(window): :close crash with autocmd, floats and tabpage" (#27796)

This reverts PR #27793.

On second thought, this solution may still crash, because it can leave a
window with a NULL buffer if there are autocommand windows or if closing
a floating window fails. It also makes close_last_window_tabpage() more
complicated, so revert it.

src/nvim/window.c

@@ -2539,47 +2539,21 @@ bool can_close_in_cmdwin(win_T *win, Error *err)
   return true;
 }
 
-/// Close the possibly last non-floating window in a tab page.
+/// Close the possibly last window in a tab page.
 ///
 /// @param  win          window to close
 /// @param  free_buf     whether to free the window's current buffer
-/// @param  force        close floating windows even if they are modified
 /// @param  prev_curtab  previous tabpage that will be closed if "win" is the
 ///                      last window in the tabpage
 ///
-/// @return false if there are other non-floating windows and nothing is done, true otherwise.
+/// @return false if there are other windows and nothing is done, true otherwise.
-static bool close_last_window_tabpage(win_T *win, bool free_buf, bool force, tabpage_T *prev_curtab)
+static bool close_last_window_tabpage(win_T *win, bool free_buf, tabpage_T *prev_curtab)
   FUNC_ATTR_NONNULL_ARG(1)
 {
-  if (!one_window(win)) {
+  if (!ONE_WINDOW) {
     return false;
   }
 
-  if (lastwin->w_floating && one_window(win)) {
-    if (is_aucmd_win(lastwin)) {
-      emsg(_("E814: Cannot close window, only autocmd window would remain"));
-      return true;
-    }
-
-    if (force || can_close_floating_windows()) {
-      // close the last window until the there are no floating windows
-      while (lastwin->w_floating) {
-        // `force` flag isn't actually used when closing a floating window.
-        if (win_close(lastwin, free_buf, true) == FAIL) {
-          // If closing the window fails give up, to avoid looping forever.
-          return true;
-        }
-      }
-    } else {
-      emsg(e_floatonly);
-      return true;
-    }
-
-    if (!win_valid_any_tab(win)) {
-      return true;  // window already closed by autocommands
-    }
-  }
-
   buf_T *old_curbuf = curbuf;
 
   Terminal *term = win->w_buffer ? win->w_buffer->terminal : NULL;
@@ -2675,11 +2649,33 @@ int win_close(win_T *win, bool free_buf, bool force)
     emsg(_(e_autocmd_close));
     return FAIL;
   }
+  if (lastwin->w_floating && one_window(win)) {
+    if (is_aucmd_win(lastwin)) {
+      emsg(_("E814: Cannot close window, only autocmd window would remain"));
+      return FAIL;
+    }
+    if (force || can_close_floating_windows()) {
+      // close the last window until the there are no floating windows
+      while (lastwin->w_floating) {
+        // `force` flag isn't actually used when closing a floating window.
+        if (win_close(lastwin, free_buf, true) == FAIL) {
+          // If closing the window fails give up, to avoid looping forever.
+          return FAIL;
+        }
+      }
+      if (!win_valid_any_tab(win)) {
+        return FAIL;  // window already closed by autocommands
+      }
+    } else {
+      emsg(e_floatonly);
+      return FAIL;
+    }
+  }
 
   // When closing the last window in a tab page first go to another tab page
   // and then close the window and the tab page to avoid that curwin and
   // curtab are invalid while we are freeing memory.
-  if (close_last_window_tabpage(win, free_buf, force, prev_curtab)) {
+  if (close_last_window_tabpage(win, free_buf, prev_curtab)) {
     return FAIL;
   }
 
@@ -2774,7 +2770,7 @@ int win_close(win_T *win, bool free_buf, bool force)
   // Autocommands may have closed the window already, or closed the only
   // other window or moved to another tab page.
   if (!win_valid(win) || (!win->w_floating && last_window(win))
-      || close_last_window_tabpage(win, free_buf, force, prev_curtab)) {
+      || close_last_window_tabpage(win, free_buf, prev_curtab)) {
     return FAIL;
   }
 

test/functional/ui/float_spec.lua

@@ -893,7 +893,7 @@ describe('float window', function()
       assert_alive()
     end)
 
-    it('does not crash if BufUnload makes it the only non-float in tabpage', function()
+    pending('does not crash if BufUnload makes it the only non-float in tabpage', function()
       exec([[
         tabnew
         let g:buf = bufnr()
@@ -909,10 +909,9 @@ describe('float window', function()
       assert_alive()
     end)
 
-    it('does not crash if WinClosed from floating windows closes it', function()
+    it('does not crash if WinClosed from floating window closes it', function()
       exec([[
         tabnew
-        let g:buf = bufnr()
         new
         let s:win = win_getid()
         call nvim_win_set_config(s:win,