Annotate ChangeTracking for nullability

Part of #19007

src/EFCore.InMemory/Query/Internal/InMemoryExpressionTranslatingExpressionVisitor.cs

@@ -1068,15 +1068,15 @@ protected override Expression VisitTypeBinary(TypeBinaryExpression typeBinaryExp
                     var valueComparer = discriminatorProperty.GetKeyValueComparer()!;
 
                     var equals = valueComparer.ExtractEqualsBody(
-                        boundProperty,
+                        boundProperty!,
                         Expression.Constant(derivedType.GetDiscriminatorValue(), discriminatorProperty.ClrType));
 
                     foreach (var derivedDerivedType in derivedType.GetDerivedTypes())
                     {
                         equals = Expression.OrElse(
                             equals,
                             valueComparer.ExtractEqualsBody(
-                                boundProperty,
+                                boundProperty!,
                                 Expression.Constant(derivedDerivedType.GetDiscriminatorValue(), discriminatorProperty.ClrType)));
                     }
 

src/EFCore/ChangeTracking/ArrayStructuralComparer.cs

@@ -3,6 +3,8 @@
 
 using System.Linq;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>

src/EFCore/ChangeTracking/CascadeTiming.cs

@@ -1,6 +1,8 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>

src/EFCore/ChangeTracking/ChangeTracker.cs

@@ -14,6 +14,8 @@
 using Microsoft.EntityFrameworkCore.Metadata.Internal;
 using Microsoft.EntityFrameworkCore.Utilities;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>
@@ -283,7 +285,7 @@ public virtual void TrackGraph(
                         return false;
                     }
 
-                    n.NodeState(n);
+                    n.NodeState!(n);
 
                     return n.Entry.State != EntityState.Detached;
                 });
@@ -321,7 +323,7 @@ public virtual void TrackGraph(
         /// <typeparam name="TState"> The type of the state object. </typeparam>
         public virtual void TrackGraph<TState>(
             [NotNull] object rootEntity,
-            [CanBeNull] TState state,
+            [CanBeNull] TState? state,
             [NotNull] Func<EntityEntryGraphNode<TState>, bool> callback)
         {
             Check.NotNull(rootEntity, nameof(rootEntity));
@@ -452,7 +454,7 @@ public virtual DebugView DebugView
         /// </summary>
         /// <returns> A string that represents the current object. </returns>
         [EditorBrowsable(EditorBrowsableState.Never)]
-        public override string ToString()
+        public override string? ToString()
             => base.ToString();
 
         /// <summary>
@@ -461,7 +463,7 @@ public override string ToString()
         /// <param name="obj"> The object to compare with the current object. </param>
         /// <returns> <see langword="true" /> if the specified object is equal to the current object; otherwise, <see langword="false" />. </returns>
         [EditorBrowsable(EditorBrowsableState.Never)]
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
             => base.Equals(obj);
 
         /// <summary>

src/EFCore/ChangeTracking/ChangeTrackerDebugStringOptions.cs

@@ -3,6 +3,8 @@
 
 using System;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>

src/EFCore/ChangeTracking/ChangeTrackerExtensions.cs

@@ -11,6 +11,8 @@
 using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Update;
 
+#nullable enable
+
 // ReSharper disable once CheckNamespace
 namespace Microsoft.EntityFrameworkCore
 {
@@ -53,8 +55,23 @@ private sealed class EntityEntryComparer : IComparer<InternalEntityEntry>
         {
             public static readonly EntityEntryComparer Instance = new();
 
-            public int Compare(InternalEntityEntry x, InternalEntityEntry y)
+            public int Compare(InternalEntityEntry? x, InternalEntityEntry? y)
             {
+                if (ReferenceEquals(x, y))
+                {
+                    return 0;
+                }
+
+                if (x is null)
+                {
+                    return -1;
+                }
+
+                if (y is null)
+                {
+                    return 1;
+                }
+
                 var result = StringComparer.InvariantCulture.Compare(x.EntityType.Name, y.EntityType.Name);
                 if (result != 0)
                 {

src/EFCore/ChangeTracking/CollectionEntry.cs

@@ -13,6 +13,8 @@
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Metadata.Internal;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>
@@ -27,7 +29,7 @@ namespace Microsoft.EntityFrameworkCore.ChangeTracking
     /// </summary>
     public class CollectionEntry : NavigationEntry
     {
-        private ICollectionLoader _loader;
+        private ICollectionLoader? _loader;
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -81,9 +83,9 @@ private void LocalDetectChanges()
         ///     the change tracker is aware of the change and <see cref="ChangeTracker.DetectChanges" /> is not required
         ///     for the context to detect the change.
         /// </summary>
-        public new virtual IEnumerable CurrentValue
+        public new virtual IEnumerable? CurrentValue
         {
-            get => (IEnumerable)base.CurrentValue;
+            get => (IEnumerable?)base.CurrentValue;
             [param: CanBeNull] set => base.CurrentValue = value;
         }
 
@@ -254,14 +256,14 @@ public override IQueryable Query()
         }
 
         private void EnsureInitialized()
-            => Metadata.GetCollectionAccessor().GetOrCreate(InternalEntry.Entity, forMaterialization: true);
+            => Metadata.GetCollectionAccessor()!.GetOrCreate(InternalEntry.Entity, forMaterialization: true);
 
         /// <summary>
         ///     The <see cref="EntityEntry" /> of an entity this navigation targets.
         /// </summary>
         /// <param name="entity"> The entity to get the entry for. </param>
         /// <value> An entry for an entity that this navigation targets. </value>
-        public virtual EntityEntry FindEntry([NotNull] object entity)
+        public virtual EntityEntry? FindEntry([NotNull] object entity)
         {
             var entry = GetInternalTargetEntry(entity);
             return entry == null
@@ -276,9 +278,9 @@ public virtual EntityEntry FindEntry([NotNull] object entity)
         ///     doing so can result in application failures when updating to a new Entity Framework Core release.
         /// </summary>
         [EntityFrameworkInternal]
-        protected virtual InternalEntityEntry GetInternalTargetEntry([NotNull] object entity)
+        protected virtual InternalEntityEntry? GetInternalTargetEntry([NotNull] object entity)
             => CurrentValue == null
-                || !Metadata.GetCollectionAccessor().Contains(InternalEntry.Entity, entity)
+                || !Metadata.GetCollectionAccessor()!.Contains(InternalEntry.Entity, entity)
                     ? null
                     : InternalEntry.StateManager.GetOrCreateEntry(entity, Metadata.TargetEntityType);
 

src/EFCore/ChangeTracking/CollectionEntry`.cs

@@ -8,6 +8,8 @@
 using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Metadata;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>
@@ -62,7 +64,7 @@ public CollectionEntry([NotNull] InternalEntityEntry internalEntry, [NotNull] IN
         ///     the change tracker is aware of the change and <see cref="ChangeTracker.DetectChanges" /> is not required
         ///     for the context to detect the change.
         /// </summary>
-        public new virtual IEnumerable<TRelatedEntity> CurrentValue
+        public new virtual IEnumerable<TRelatedEntity>? CurrentValue
         {
             get => this.GetInfrastructure().GetCurrentValue<IEnumerable<TRelatedEntity>>(Metadata);
             [param: CanBeNull] set => base.CurrentValue = value;
@@ -90,7 +92,7 @@ public CollectionEntry([NotNull] InternalEntityEntry internalEntry, [NotNull] IN
         /// </summary>
         /// <param name="entity"> The entity to get the entry for. </param>
         /// <value> An entry for an entity that this navigation targets. </value>
-        public new virtual EntityEntry<TRelatedEntity> FindEntry([NotNull] object entity)
+        public new virtual EntityEntry<TRelatedEntity>? FindEntry([NotNull] object entity)
         {
             var entry = GetInternalTargetEntry(entity);
             return entry == null

src/EFCore/ChangeTracking/EntityEntry.cs

@@ -18,6 +18,8 @@
 using Microsoft.EntityFrameworkCore.Update;
 using Microsoft.EntityFrameworkCore.Utilities;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>
@@ -33,7 +35,7 @@ namespace Microsoft.EntityFrameworkCore.ChangeTracking
     public class EntityEntry : IInfrastructure<InternalEntityEntry>
     {
         private static readonly int _maxEntityState = Enum.GetValues(typeof(EntityState)).Cast<int>().Max();
-        private IEntityFinder _finder;
+        private IEntityFinder? _finder;
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -146,7 +148,7 @@ public virtual MemberEntry Member([NotNull] string propertyName)
                 return new PropertyEntry(InternalEntry, propertyName);
             }
 
-            var navigation = (INavigationBase)InternalEntry.EntityType.FindNavigation(propertyName)
+            var navigation = (INavigationBase?)InternalEntry.EntityType.FindNavigation(propertyName)
                 ?? InternalEntry.EntityType.FindSkipNavigation(propertyName);
             if (navigation != null)
             {
@@ -176,7 +178,7 @@ public virtual NavigationEntry Navigation([NotNull] string propertyName)
         {
             Check.NotEmpty(propertyName, nameof(propertyName));
 
-            var navigation = (INavigationBase)InternalEntry.EntityType.FindNavigation(propertyName)
+            var navigation = (INavigationBase?)InternalEntry.EntityType.FindNavigation(propertyName)
                 ?? InternalEntry.EntityType.FindSkipNavigation(propertyName);
 
             if (navigation != null)
@@ -345,7 +347,7 @@ public virtual PropertyValues OriginalValues
         ///     </para>
         /// </summary>
         /// <returns> The store values, or null if the entity does not exist in the database. </returns>
-        public virtual PropertyValues GetDatabaseValues()
+        public virtual PropertyValues? GetDatabaseValues()
         {
             var values = Finder.GetDatabaseValues(InternalEntry);
 
@@ -372,7 +374,7 @@ public virtual PropertyValues GetDatabaseValues()
         ///     or <see langword="null" /> if the entity does not exist in the database.
         /// </returns>
         /// <exception cref="OperationCanceledException"> If the <see cref="CancellationToken"/> is canceled. </exception>
-        public virtual async Task<PropertyValues> GetDatabaseValuesAsync(CancellationToken cancellationToken = default)
+        public virtual async Task<PropertyValues?> GetDatabaseValuesAsync(CancellationToken cancellationToken = default)
         {
             var values = await Finder.GetDatabaseValuesAsync(InternalEntry, cancellationToken)
                 .ConfigureAwait(false);
@@ -413,7 +415,7 @@ public virtual void Reload()
         public virtual async Task ReloadAsync(CancellationToken cancellationToken = default)
             => Reload(await GetDatabaseValuesAsync(cancellationToken).ConfigureAwait(false));
 
-        private void Reload(PropertyValues storeValues)
+        private void Reload(PropertyValues? storeValues)
         {
             if (storeValues == null)
             {
@@ -463,7 +465,7 @@ public virtual DebugView DebugView
         /// <param name="obj"> The object to compare with the current object. </param>
         /// <returns> <see langword="true" /> if the specified object is equal to the current object; otherwise, <see langword="false" />. </returns>
         [EditorBrowsable(EditorBrowsableState.Never)]
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
             => base.Equals(obj);
 
         /// <summary>

src/EFCore/ChangeTracking/EntityEntryEventArgs.cs

@@ -6,6 +6,8 @@
 using Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
 using Microsoft.EntityFrameworkCore.Infrastructure;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>
@@ -14,7 +16,7 @@ namespace Microsoft.EntityFrameworkCore.ChangeTracking
     public class EntityEntryEventArgs : EventArgs
     {
         private readonly InternalEntityEntry _internalEntityEntry;
-        private EntityEntry _entry;
+        private EntityEntry? _entry;
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to

src/EFCore/ChangeTracking/EntityEntryGraphNode.cs

@@ -8,6 +8,10 @@
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Utilities;
 
+using CA = System.Diagnostics.CodeAnalysis;
+
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>
@@ -22,7 +26,7 @@ namespace Microsoft.EntityFrameworkCore.ChangeTracking
     public class EntityEntryGraphNode : IInfrastructure<InternalEntityEntry>
     {
         private readonly InternalEntityEntry _entry;
-        private readonly InternalEntityEntry _sourceEntry;
+        private readonly InternalEntityEntry? _sourceEntry;
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -34,8 +38,8 @@ public class EntityEntryGraphNode : IInfrastructure<InternalEntityEntry>
         [EntityFrameworkInternal]
         public EntityEntryGraphNode(
             [NotNull] InternalEntityEntry entry,
-            [CanBeNull] InternalEntityEntry sourceEntry,
-            [CanBeNull] INavigationBase inboundNavigation)
+            [CanBeNull] InternalEntityEntry? sourceEntry,
+            [CanBeNull] INavigationBase? inboundNavigation)
         {
             Check.NotNull(entry, nameof(entry));
 
@@ -53,7 +57,7 @@ public EntityEntryGraphNode(
         ///         See <see cref="M:ChangeTracker.TrackGraph" /> for information on how graph nodes are used.
         ///     </para>
         /// </summary>
-        public virtual EntityEntry SourceEntry
+        public virtual EntityEntry? SourceEntry
             => _sourceEntry == null ? null : new EntityEntry(_sourceEntry);
 
         /// <summary>
@@ -64,7 +68,7 @@ public virtual EntityEntry SourceEntry
         ///         See <see cref="M:ChangeTracker.TrackGraph" /> for information on how graph nodes are used.
         ///     </para>
         /// </summary>
-        public virtual INavigationBase InboundNavigation { get; }
+        public virtual INavigationBase? InboundNavigation { get; }
 
         /// <summary>
         ///     <para>

src/EFCore/ChangeTracking/EntityEntryGraphNode`.cs

@@ -8,6 +8,8 @@
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Utilities;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>
@@ -26,9 +28,9 @@ public class EntityEntryGraphNode<TState> : EntityEntryGraphNode
         [EntityFrameworkInternal]
         public EntityEntryGraphNode(
             [NotNull] InternalEntityEntry entry,
-            [CanBeNull] TState state,
-            [CanBeNull] InternalEntityEntry sourceEntry,
-            [CanBeNull] INavigationBase inboundNavigation)
+            [CanBeNull] TState? state,
+            [CanBeNull] InternalEntityEntry? sourceEntry,
+            [CanBeNull] INavigationBase? inboundNavigation)
             : base(entry, sourceEntry, inboundNavigation)
         {
             NodeState = state;
@@ -37,7 +39,7 @@ public EntityEntryGraphNode(
         /// <summary>
         ///     Gets or sets state that will be available to all nodes that are visited after this node.
         /// </summary>
-        public virtual TState NodeState { get; [param: CanBeNull] set; }
+        public virtual TState? NodeState { get; [param: CanBeNull] set; }
 
         /// <summary>
         ///     Creates a new node for the entity that is being traversed next in the graph.

src/EFCore/ChangeTracking/EntityEntry`.cs

@@ -12,6 +12,8 @@
 using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.Utilities;
 
+#nullable enable
+
 namespace Microsoft.EntityFrameworkCore.ChangeTracking
 {
     /// <summary>
@@ -155,7 +157,7 @@ public virtual PropertyEntry<TEntity, TProperty> Property<TProperty>(
             return new PropertyEntry<TEntity, TProperty>(InternalEntry, propertyName);
         }
 
-        private static void ValidateType<TProperty>(IProperty property)
+        private static void ValidateType<TProperty>(IProperty? property)
         {
             if (property != null
                 && property.ClrType != typeof(TProperty))