Fixing IndexOutOfRangeException throwing by DGV when disposing its DataSource

src/System.Windows.Forms/src/System/Windows/Forms/BindingNavigator.cs

@@ -767,6 +767,14 @@ private void OnBindingSourceStateChanged(object sender, EventArgs e)
             RefreshItemsInternal();
         }
 
+        /// <summary>
+        ///  Refresh tool strip items when the BindingSource is disposed.
+        /// </summary>
+        private void OnBindingSourceDisposed(object sender, EventArgs e)
+        {
+            BindingSource = null;
+        }
+
         /// <summary>
         ///  Refresh tool strip items when something changes in the BindingSource's list.
         /// </summary>
@@ -895,6 +903,7 @@ private void WireUpBindingSource(ref BindingSource oldBindingSource, BindingSour
                     oldBindingSource.DataSourceChanged -= new EventHandler(OnBindingSourceStateChanged);
                     oldBindingSource.DataMemberChanged -= new EventHandler(OnBindingSourceStateChanged);
                     oldBindingSource.ListChanged -= new ListChangedEventHandler(OnBindingSourceListChanged);
+                    oldBindingSource.Disposed -= new EventHandler(OnBindingSourceDisposed);
                 }
 
                 if (newBindingSource is not null)
@@ -905,6 +914,7 @@ private void WireUpBindingSource(ref BindingSource oldBindingSource, BindingSour
                     newBindingSource.DataSourceChanged += new EventHandler(OnBindingSourceStateChanged);
                     newBindingSource.DataMemberChanged += new EventHandler(OnBindingSourceStateChanged);
                     newBindingSource.ListChanged += new ListChangedEventHandler(OnBindingSourceListChanged);
+                    newBindingSource.Disposed += new EventHandler(OnBindingSourceDisposed);
                 }
 
                 oldBindingSource = newBindingSource;

src/System.Windows.Forms/src/System/Windows/Forms/DataGridView.Methods.cs

@@ -14861,6 +14861,14 @@ protected virtual void OnDataSourceChanged(EventArgs e)
             }
         }
 
+        /// <summary>
+        ///  Refresh items when the DataSource is disposed.
+        /// </summary>
+        private void OnDataSourceDisposed(object sender, EventArgs e)
+        {
+            DataSource = null;
+        }
+
         protected virtual void OnDefaultCellStyleChanged(EventArgs e)
         {
             if (e is DataGridViewCellStyleChangedEventArgs dgvcsce && !dgvcsce.ChangeAffectsPreferredSize)

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

@@ -2014,6 +2014,16 @@ public object DataSource
             {
                 if (value != DataSource)
                 {
+                    if (DataSource is Component oldDataSource)
+                    {
+                        oldDataSource.Disposed -= OnDataSourceDisposed;
+                    }
+
+                    if (value is Component newDataSource)
+                    {
+                        newDataSource.Disposed += OnDataSourceDisposed;
+                    }
+
                     CurrentCell = null;
                     if (DataConnection is null)
                     {

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

@@ -4,6 +4,7 @@
 
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Data;
 using System.Diagnostics;
 using Moq;
 using Xunit;
@@ -129,5 +130,86 @@ public void BindingNavigator_ConstructorBool()
             Assert.Equal(bn.AddNewItem, bn.Items[index++]);
             Assert.Equal(bn.DeleteItem, bn.Items[index++]);
         }
+
+        [WinFormsFact]
+        public void BindingNavigator_UpdatesItsItems_AfterDataSourceDisposing()
+        {
+            using BindingNavigator control = new BindingNavigator(true);
+            int rowsCount = 5;
+            BindingSource bindingSource = GetTestBindingSource(rowsCount);
+            control.BindingSource = bindingSource;
+
+            Assert.Equal("1", control.PositionItem.Text);
+            Assert.Equal($"of {rowsCount}", control.CountItem.Text);
+
+            bindingSource.Dispose();
+
+            // The BindingNavigator updates its PositionItem and CountItem values
+            // after its BindingSource is disposed
+            Assert.Equal("0", control.PositionItem.Text);
+            Assert.Equal("of 0", control.CountItem.Text);
+        }
+
+        [WinFormsFact]
+        public void BindingNavigator_BindingSource_IsNull_AfterDisposing()
+        {
+            using BindingNavigator control = new BindingNavigator();
+            BindingSource bindingSource = GetTestBindingSource(5);
+            control.BindingSource = bindingSource;
+
+            Assert.Equal(bindingSource, control.BindingSource);
+
+            bindingSource.Dispose();
+
+            Assert.Null(control.BindingSource);
+        }
+
+        [WinFormsFact]
+        public void BindingNavigator_BindingSource_IsActual_AfterOldOneIsDisposed()
+        {
+            using BindingNavigator control = new BindingNavigator(true);
+            int rowsCount1 = 3;
+            BindingSource bindingSource1 = GetTestBindingSource(rowsCount1);
+            int rowsCount2 = 5;
+            BindingSource bindingSource2 = GetTestBindingSource(rowsCount2);
+            control.BindingSource = bindingSource1;
+
+            Assert.Equal(bindingSource1, control.BindingSource);
+            Assert.Equal("1", control.PositionItem.Text);
+            Assert.Equal($"of {rowsCount1}", control.CountItem.Text);
+
+            control.BindingSource = bindingSource2;
+
+            Assert.Equal(bindingSource2, control.BindingSource);
+            Assert.Equal("1", control.PositionItem.Text);
+            Assert.Equal($"of {rowsCount2}", control.CountItem.Text);
+
+            bindingSource1.Dispose();
+
+            // bindingSource2 is actual for the BindingNavigator
+            // so it will contain correct PositionItem and CountItem values
+            // even after bindingSource1 is disposed.
+            // This test checks that Disposed events unsubscribed correctly
+            Assert.Equal(bindingSource2, control.BindingSource);
+            Assert.Equal("1", control.PositionItem.Text);
+            Assert.Equal($"of {rowsCount2}", control.CountItem.Text);
+        }
+
+        private BindingSource GetTestBindingSource(int rowsCount)
+        {
+            DataTable dt = new DataTable();
+            dt.Columns.Add("Name");
+            dt.Columns.Add("Age");
+
+            for (int i = 0; i < rowsCount; i++)
+            {
+                DataRow dr = dt.NewRow();
+                dr[0] = $"User{i}";
+                dr[1] = i * 3;
+                dt.Rows.Add(dr);
+            }
+
+            return new() { DataSource = dt };
+        }
     }
 }

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

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
@@ -11,6 +11,7 @@
 using System.Numerics;
 using static System.Windows.Forms.Metafiles.DataHelpers;
 using static Interop;
+using System.Data;
 
 namespace System.Windows.Forms.Tests
 {
@@ -2801,6 +2802,92 @@ public void DataGridView_OnRowHeadersWidthSizeModeChanged_NullE_ThrowsNullRefere
             Assert.Throws<NullReferenceException>(() => control.OnRowHeadersWidthSizeModeChanged(null));
         }
 
+        [WinFormsFact]
+        public void DataGridView_UpdatesItsItems_AfterDataSourceDisposing()
+        {
+            using DataGridView control = new DataGridView();
+            int rowsCount = 5;
+            BindingSource bindingSource = GetTestBindingSource(rowsCount);
+            BindingContext context = new BindingContext();
+            context.Add(bindingSource, bindingSource.CurrencyManager);
+            control.BindingContext = context;
+            control.DataSource = bindingSource;
+
+            // The TestBindingSource table contains 2 columns
+            Assert.Equal(2, control.Columns.Count);
+            // The TestBindingSource table contains some rows + 1 new DGV row (because AllowUserToAddRows is true)
+            Assert.Equal(rowsCount + 1, control.Rows.Count);
+
+            bindingSource.Dispose();
+
+            // The DataGridView updates its Rows and Columns collections after its DataSource is disposed
+            Assert.Empty(control.Columns);
+            Assert.Empty(control.Rows);
+        }
+
+        [WinFormsFact]
+        public void DataGridView_DataSource_IsNull_AfterDisposing()
+        {
+            using DataGridView control = new DataGridView();
+            BindingSource bindingSource = GetTestBindingSource(5);
+            control.DataSource = bindingSource;
+
+            Assert.Equal(bindingSource, control.DataSource);
+
+            bindingSource.Dispose();
+
+            Assert.Null(control.DataSource);
+        }
+
+        [WinFormsFact]
+        public void DataGridView_DataSource_IsActual_AfterOldOneIsDisposed()
+        {
+            using DataGridView control = new DataGridView();
+            int rowsCount1 = 3;
+            BindingSource bindingSource1 = GetTestBindingSource(rowsCount1);
+            int rowsCount2 = 5;
+            BindingSource bindingSource2 = GetTestBindingSource(rowsCount2);
+            BindingContext context = new BindingContext();
+            context.Add(bindingSource1, bindingSource1.CurrencyManager);
+            control.BindingContext = context;
+            control.DataSource = bindingSource1;
+
+            Assert.Equal(bindingSource1, control.DataSource);
+            Assert.Equal(2, control.Columns.Count);
+            Assert.Equal(rowsCount1 + 1, control.Rows.Count); // + 1 is the new DGV row
+
+            control.DataSource = bindingSource2;
+
+            Assert.Equal(bindingSource2, control.DataSource);
+            Assert.Equal(2, control.Columns.Count);
+            Assert.Equal(rowsCount2 + 1, control.Rows.Count); // + 1 is the new DGV row
+
+            bindingSource1.Dispose();
+
+            // bindingSource2 is actual for the DataGridView so it will contain correct Rows and Columns counts
+            // even after bindingSource1 is disposed. This test checks that Disposed events unsubscribed correctly
+            Assert.Equal(bindingSource2, control.DataSource);
+            Assert.Equal(2, control.Columns.Count);
+            Assert.Equal(rowsCount2 + 1, control.Rows.Count); // + 1 is the new DGV row
+        }
+
+        private BindingSource GetTestBindingSource(int rowsCount)
+        {
+            DataTable dt = new DataTable();
+            dt.Columns.Add("Name");
+            dt.Columns.Add("Age");
+
+            for (int i = 0; i < rowsCount; i++)
+            {
+                DataRow dr = dt.NewRow();
+                dr[0] = $"User{i}";
+                dr[1] = i * 3;
+                dt.Rows.Add(dr);
+            }
+
+            return new() { DataSource = dt };
+        }
+
         private class SubDataGridViewCell : DataGridViewCell
         {
         }