fix(win_close): remove float grid after closing buffer (#21551)

It is not safe to remove the float grid when autocommands can still be
triggered, as autocommands may use the float grid.

2 files changed, 50 insertions, 22 deletions

diff --git a/src/nvim/window.c b/src/nvim/window.c
index d026f4551a..fe771c52c6 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -2764,28 +2764,6 @@ int win_close(win_T *win, bool free_buf, bool force)
     }
   }
 
-  bool was_floating = win->w_floating;
-  if (ui_has(kUIMultigrid)) {
-    ui_call_win_close(win->w_grid_alloc.handle);
-  }
-
-  if (win->w_floating) {
-    ui_comp_remove_grid(&win->w_grid_alloc);
-    assert(first_tabpage != NULL);  // suppress clang "Dereference of NULL pointer"
-    if (win->w_float_config.external) {
-      for (tabpage_T *tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
-        if (tp == curtab) {
-          continue;
-        }
-        if (tp->tp_curwin == win) {
-          // NB: an autocmd can still abort the closing of this window,
-          // bur carring out this change anyway shouldn't be a catastrophe.
-          tp->tp_curwin = tp->tp_firstwin;
-        }
-      }
-    }
-  }
-
   // Fire WinClosed just before starting to free window-related resources.
   do_autocmd_winclosed(win);
   // autocmd may have freed the window already.
@@ -2831,6 +2809,28 @@ int win_close(win_T *win, bool free_buf, bool force)
   // let terminal buffers know that this window dimensions may be ignored
   win->w_closing = true;
 
+  bool was_floating = win->w_floating;
+  if (ui_has(kUIMultigrid)) {
+    ui_call_win_close(win->w_grid_alloc.handle);
+  }
+
+  if (win->w_floating) {
+    ui_comp_remove_grid(&win->w_grid_alloc);
+    assert(first_tabpage != NULL);  // suppress clang "Dereference of NULL pointer"
+    if (win->w_float_config.external) {
+      for (tabpage_T *tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
+        if (tp == curtab) {
+          continue;
+        }
+        if (tp->tp_curwin == win) {
+          // NB: an autocmd can still abort the closing of this window,
+          // bur carring out this change anyway shouldn't be a catastrophe.
+          tp->tp_curwin = tp->tp_firstwin;
+        }
+      }
+    }
+  }
+
   // Free the memory used for the window and get the window that received
   // the screen space.
   int dir;
diff --git a/test/functional/ui/float_spec.lua b/test/functional/ui/float_spec.lua
index bb09cfd504..ab87384194 100644
--- a/test/functional/ui/float_spec.lua
+++ b/test/functional/ui/float_spec.lua
@@ -8831,6 +8831,34 @@ describe('float window', function()
         ]]}
       end
     end)
+
+    describe('no crash after moving and closing float window #21547', function()
+      local function test_float_move_close(cmd)
+        local float_opts = {relative = 'editor', row = 1, col = 1, width = 10, height = 10}
+        meths.open_win(meths.create_buf(false, false), true, float_opts)
+        if multigrid then
+          screen:expect({float_pos = {[4] = {{id = 1001}, 'NW', 1, 1, 1, true}}})
+        end
+        command(cmd)
+        exec_lua([[
+          vim.api.nvim_win_set_config(0, {relative = 'editor', row = 2, col = 2})
+          vim.api.nvim_win_close(0, {})
+          vim.api.nvim_echo({{''}}, false, {})
+        ]])
+        if multigrid then
+          screen:expect({float_pos = {}})
+        end
+        assert_alive()
+      end
+
+      it('if WinClosed autocommand flushes UI', function()
+        test_float_move_close('autocmd WinClosed * ++once redraw')
+      end)
+
+      it('if closing buffer flushes UI', function()
+        test_float_move_close('autocmd BufWinLeave * ++once redraw')
+      end)
+    end)
   end
 
   describe('with ext_multigrid', function()