[release/9.0] Add a null-check for "DataGridView" property before executing OnMouseUp in function OnMouseUpInternal (#12742)

Backport of #12701 to release/9.0


Customer Impact
Application crashes when the customer clicks on a DataGridView cell, where previously the content was selected.

Root Cause
    This issue is caused by PR Enable nullability in remaining DataGridViewCell members #10406. which removed the check whether the parent control is null before executing OnMouseUp when handling a MouseUp event. That fix moved the null check to the top of our MouseUp event handler. However, reference to the parent control can be set to null when this cell (or a row containing it) is cleared in the user-provided click event handler which is invoked in the middle of this method. We should restore the null check before accessing the parent DataGridView.

Author: github-actions[bot]

src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridViewCell.cs

@@ -3075,7 +3075,9 @@ internal void OnMouseUpInternal(DataGridViewCellMouseEventArgs e)
             DataGridView.OnCommonCellContentClick(e.ColumnIndex, e.RowIndex, e.Clicks > 1);
         }
 
-        if (e.ColumnIndex < DataGridView.Columns.Count && e.RowIndex < DataGridView.Rows.Count)
+        // Verify that the DataGridView is not null again, because a custom
+        // Click event handler may delete the cell and the reference to parent DataGridView.
+        if (DataGridView is not null && e.ColumnIndex < DataGridView.Columns.Count && e.RowIndex < DataGridView.Rows.Count)
         {
             OnMouseUp(e);
         }
@@ -3795,16 +3797,16 @@ public virtual void PositionEditingControl(
             isFirstDisplayedColumn,
             isFirstDisplayedRow);
 
-        if (DataGridView?.EditingControl is not null)
+        if (DataGridView?.EditingControl is { } editingControl)
         {
             if (setLocation)
             {
-                DataGridView.EditingControl.Location = new Point(editingControlBounds.X, editingControlBounds.Y);
+                editingControl.Location = new Point(editingControlBounds.X, editingControlBounds.Y);
             }
 
             if (setSize)
             {
-                DataGridView.EditingControl.Size = new Size(editingControlBounds.Width, editingControlBounds.Height);
+                editingControl.Size = new Size(editingControlBounds.Width, editingControlBounds.Height);
             }
         }
     }

src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/DataGridViewCellTests.cs

@@ -6603,6 +6603,32 @@ public void DataGridViewCell_OnContentClick_InvokeInternalRaiseAutomationNotific
             Times.Exactly(2));
     }
 
+    // Regression test for https://github.com/dotnet/winforms/issues/12692
+    [WinFormsFact]
+    public void DataGridViewCell_OnContentClick_ClearAndReAddCell_InvokeOnMouseUpInternal()
+    {
+        using SubDataGridViewCheckBoxCell cellTemplate = new();
+        using DataGridViewColumn column = new()
+        {
+            CellTemplate = cellTemplate
+        };
+
+        using DataGridView dataGridView = new();
+        dataGridView.Columns.Add(column);
+        var cell = (SubDataGridViewCheckBoxCell)dataGridView.Rows[0].Cells[0];
+
+        dataGridView.CellContentClick += new DataGridViewCellEventHandler((s, e) =>
+        {
+            DataGridView dataGridView = (DataGridView)s;
+            dataGridView.Rows.Clear();
+            dataGridView.Rows.Add();
+        });
+        // Set cell value to ensure it is properly formatted.
+        cell.Value = false;
+        Action act = () => cell.MouseClick(new DataGridViewCellMouseEventArgs(0, 0, 10, 10, new MouseEventArgs(MouseButtons.Left, 1, 10, 10, 0)));
+        act.Should().NotThrow();
+    }
+
     private class SubDataGridViewCheckBoxCell : DataGridViewCheckBoxCell
     {
         public SubDataGridViewCheckBoxCell()