[Group 1] Enable nullable annotations for `Microsoft.Extensions.Primi…

…tives` (#57395)

* Annotate src

* StringValues array is non-nullable

* Anotate ref

* Fix analizer error

* Update Equals implementation

* Result of IChangeToken.RegisterChangeCallback is nullable

* Revert "Result of IChangeToken.RegisterChangeCallback is nullable"

This reverts commit e005156.

* Dont use using in ref

* Commit to rerun CI

* Revert "Commit to rerun CI"

This reverts commit d7230db.

* StringValues can contain string?[]

* Equals [NotNullWhen(true)]

* text = null - retrun false

* text = null - retrun false (tests)

* Remove unneeded ?.

* IChangeToken can be null

* Update doc

* NullTokenDisposeShouldNotThrow

* _registeredCallbackProxy -> RegisteredCallbackProxy

* StringValues can be created from string?[]?

* Debug.Fail -> Assert.True(false)

src/libraries/Microsoft.Extensions.Primitives/ref/Microsoft.Extensions.Primitives.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);netcoreapp3.1;netstandard2.0;net461</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Microsoft.Extensions.Primitives.cs" />

src/libraries/Microsoft.Extensions.Primitives/src/CancellationChangeToken.cs

@@ -29,7 +29,7 @@ public CancellationChangeToken(CancellationToken cancellationToken)
         private CancellationToken Token { get; }
 
         /// <inheritdoc />
-        public IDisposable RegisterChangeCallback(Action<object> callback, object state)
+        public IDisposable RegisterChangeCallback(Action<object?> callback, object? state)
         {
 #if NETCOREAPP || NETSTANDARD2_1
             try

src/libraries/Microsoft.Extensions.Primitives/src/ChangeToken.cs

@@ -18,7 +18,7 @@ public static class ChangeToken
         /// <param name="changeTokenProducer">Produces the change token.</param>
         /// <param name="changeTokenConsumer">Action called when the token changes.</param>
         /// <returns></returns>
-        public static IDisposable OnChange(Func<IChangeToken> changeTokenProducer, Action changeTokenConsumer)
+        public static IDisposable OnChange(Func<IChangeToken?> changeTokenProducer, Action changeTokenConsumer)
         {
             if (changeTokenProducer == null)
             {
@@ -39,7 +39,7 @@ public static IDisposable OnChange(Func<IChangeToken> changeTokenProducer, Actio
         /// <param name="changeTokenConsumer">Action called when the token changes.</param>
         /// <param name="state">state for the consumer.</param>
         /// <returns></returns>
-        public static IDisposable OnChange<TState>(Func<IChangeToken> changeTokenProducer, Action<TState> changeTokenConsumer, TState state)
+        public static IDisposable OnChange<TState>(Func<IChangeToken?> changeTokenProducer, Action<TState> changeTokenConsumer, TState state)
         {
             if (changeTokenProducer == null)
             {
@@ -55,20 +55,20 @@ public static IDisposable OnChange<TState>(Func<IChangeToken> changeTokenProduce
 
         private sealed class ChangeTokenRegistration<TState> : IDisposable
         {
-            private readonly Func<IChangeToken> _changeTokenProducer;
+            private readonly Func<IChangeToken?> _changeTokenProducer;
             private readonly Action<TState> _changeTokenConsumer;
             private readonly TState _state;
-            private IDisposable _disposable;
+            private IDisposable? _disposable;
 
             private static readonly NoopDisposable _disposedSentinel = new NoopDisposable();
 
-            public ChangeTokenRegistration(Func<IChangeToken> changeTokenProducer, Action<TState> changeTokenConsumer, TState state)
+            public ChangeTokenRegistration(Func<IChangeToken?> changeTokenProducer, Action<TState> changeTokenConsumer, TState state)
             {
                 _changeTokenProducer = changeTokenProducer;
                 _changeTokenConsumer = changeTokenConsumer;
                 _state = state;
 
-                IChangeToken token = changeTokenProducer();
+                IChangeToken? token = changeTokenProducer();
 
                 RegisterChangeTokenCallback(token);
             }
@@ -80,7 +80,7 @@ private void OnChangeTokenFired()
                 //
                 // If the token changes after we take the token, then we'll process the update immediately upon
                 // registering the callback.
-                IChangeToken token = _changeTokenProducer();
+                IChangeToken? token = _changeTokenProducer();
 
                 try
                 {
@@ -93,14 +93,14 @@ private void OnChangeTokenFired()
                 }
             }
 
-            private void RegisterChangeTokenCallback(IChangeToken token)
+            private void RegisterChangeTokenCallback(IChangeToken? token)
             {
                 if (token is null)
                 {
                     return;
                 }
 
-                IDisposable registraton = token.RegisterChangeCallback(s => ((ChangeTokenRegistration<TState>)s).OnChangeTokenFired(), this);
+                IDisposable registraton = token.RegisterChangeCallback(s => ((ChangeTokenRegistration<TState>?)s)!.OnChangeTokenFired(), this);
 
                 SetDisposable(registraton);
             }
@@ -110,7 +110,7 @@ private void SetDisposable(IDisposable disposable)
                 // We don't want to transition from _disposedSentinel => anything since it's terminal
                 // but we want to allow going from previously assigned disposable, to another
                 // disposable.
-                IDisposable current = Volatile.Read(ref _disposable);
+                IDisposable? current = Volatile.Read(ref _disposable);
 
                 // If Dispose was called, then immediately dispose the disposable
                 if (current == _disposedSentinel)
@@ -120,7 +120,7 @@ private void SetDisposable(IDisposable disposable)
                 }
 
                 // Otherwise, try to update the disposable
-                IDisposable previous = Interlocked.CompareExchange(ref _disposable, disposable, current);
+                IDisposable? previous = Interlocked.CompareExchange(ref _disposable, disposable, current);
 
                 if (previous == _disposedSentinel)
                 {
@@ -129,7 +129,7 @@ private void SetDisposable(IDisposable disposable)
                 }
                 else if (previous == current)
                 {
-                    // We successfuly assigned the _disposable field to disposable
+                    // We successfully assigned the _disposable field to disposable
                 }
                 else
                 {
@@ -142,7 +142,7 @@ public void Dispose()
             {
                 // If the previous value is disposable then dispose it, otherwise,
                 // now we've set the disposed sentinel
-                Interlocked.Exchange(ref _disposable, _disposedSentinel).Dispose();
+                Interlocked.Exchange(ref _disposable, _disposedSentinel)?.Dispose();
             }
 
             private sealed class NoopDisposable : IDisposable

src/libraries/Microsoft.Extensions.Primitives/src/CompositeChangeToken.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Threading;
 
 namespace Microsoft.Extensions.Primitives
@@ -13,11 +14,14 @@ namespace Microsoft.Extensions.Primitives
     /// </summary>
     public class CompositeChangeToken : IChangeToken
     {
-        private static readonly Action<object> _onChangeDelegate = OnChange;
-        private readonly object _callbackLock = new object();
-        private CancellationTokenSource _cancellationTokenSource;
-        private bool _registeredCallbackProxy;
-        private List<IDisposable> _disposables;
+        private static readonly Action<object?> _onChangeDelegate = OnChange;
+        private readonly object _callbackLock = new();
+        private CancellationTokenSource? _cancellationTokenSource;
+        private List<IDisposable>? _disposables;
+
+        [MemberNotNullWhen(true, nameof(_cancellationTokenSource))]
+        [MemberNotNullWhen(true, nameof(_disposables))]
+        private bool RegisteredCallbackProxy { get; set; }
 
         /// <summary>
         /// Creates a new instance of <see cref="CompositeChangeToken"/>.
@@ -42,7 +46,7 @@ public CompositeChangeToken(IReadOnlyList<IChangeToken> changeTokens)
         public IReadOnlyList<IChangeToken> ChangeTokens { get; }
 
         /// <inheritdoc />
-        public IDisposable RegisterChangeCallback(Action<object> callback, object state)
+        public IDisposable RegisterChangeCallback(Action<object?> callback, object? state)
         {
             EnsureCallbacksInitialized();
             return _cancellationTokenSource.Token.Register(callback, state);
@@ -74,16 +78,18 @@ public bool HasChanged
         /// <inheritdoc />
         public bool ActiveChangeCallbacks { get; }
 
+        [MemberNotNull(nameof(_cancellationTokenSource))]
+        [MemberNotNull(nameof(_disposables))]
         private void EnsureCallbacksInitialized()
         {
-            if (_registeredCallbackProxy)
+            if (RegisteredCallbackProxy)
             {
                 return;
             }
 
             lock (_callbackLock)
             {
-                if (_registeredCallbackProxy)
+                if (RegisteredCallbackProxy)
                 {
                     return;
                 }
@@ -98,12 +104,14 @@ private void EnsureCallbacksInitialized()
                         _disposables.Add(disposable);
                     }
                 }
-                _registeredCallbackProxy = true;
+                RegisteredCallbackProxy = true;
             }
         }
 
-        private static void OnChange(object state)
+        private static void OnChange(object? state)
         {
+            Debug.Assert(state != null);
+
             var compositeChangeTokenState = (CompositeChangeToken)state;
             if (compositeChangeTokenState._cancellationTokenSource == null)
             {
@@ -121,13 +129,12 @@ private static void OnChange(object state)
                 }
             }
 
-            List<IDisposable> disposables = compositeChangeTokenState._disposables;
+            List<IDisposable>? disposables = compositeChangeTokenState._disposables;
             Debug.Assert(disposables != null);
             for (int i = 0; i < disposables.Count; i++)
             {
                 disposables[i].Dispose();
             }
-
         }
     }
 }

src/libraries/Microsoft.Extensions.Primitives/src/IChangeToken.cs

@@ -28,6 +28,6 @@ public interface IChangeToken
         /// <param name="callback">The <see cref="Action{Object}"/> to invoke.</param>
         /// <param name="state">State to be passed into the callback.</param>
         /// <returns>An <see cref="IDisposable"/> that is used to unregister the callback.</returns>
-        IDisposable RegisterChangeCallback(Action<object> callback, object state);
+        IDisposable RegisterChangeCallback(Action<object?> callback, object? state);
     }
 }

src/libraries/Microsoft.Extensions.Primitives/src/Microsoft.Extensions.Primitives.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);netcoreapp3.1;netstandard2.0;net461</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <EnableDefaultItems>true</EnableDefaultItems>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <!-- Use targeting pack references instead of granular ones in the project file. -->

src/libraries/Microsoft.Extensions.Primitives/src/StringSegment.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 
 namespace Microsoft.Extensions.Primitives
@@ -76,11 +77,12 @@ public StringSegment(string buffer, int offset, int length)
         /// <summary>
         /// Gets the value of this segment as a <see cref="string"/>.
         /// </summary>
-        public string Value => HasValue ? Buffer.Substring(Offset, Length) : null;
+        public string? Value => HasValue ? Buffer.Substring(Offset, Length) : null;
 
         /// <summary>
         /// Gets whether this <see cref="StringSegment"/> contains a valid value.
         /// </summary>
+        [MemberNotNullWhen(true, nameof(Buffer))]
         public bool HasValue => Buffer != null;
 
         /// <summary>
@@ -188,7 +190,7 @@ public static int Compare(StringSegment a, StringSegment b, StringComparison com
         /// </summary>
         /// <param name="obj">An object to compare with this object.</param>
         /// <returns><see langword="true" /> if the current object is equal to the other parameter; otherwise, <see langword="false" />.</returns>
-        public override bool Equals(object obj)
+        public override bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is StringSegment segment && Equals(segment);
         }
@@ -239,7 +241,7 @@ public static bool Equals(StringSegment a, StringSegment b, StringComparison com
         /// </summary>
         /// <param name="text">The <see cref="string"/> to compare with the current <see cref="StringSegment"/>.</param>
         /// <returns><see langword="true" /> if the specified <see cref="string"/> is equal to the current <see cref="StringSegment"/>; otherwise, <see langword="false" />.</returns>
-        public bool Equals(string text)
+        public bool Equals([NotNullWhen(true)] string? text)
         {
             return Equals(text, StringComparison.Ordinal);
         }
@@ -250,15 +252,12 @@ public bool Equals(string text)
         /// <param name="text">The <see cref="string"/> to compare with the current <see cref="StringSegment"/>.</param>
         /// <param name="comparisonType">One of the enumeration values that specifies the rules to use in the comparison.</param>
         /// <returns><see langword="true" /> if the specified <see cref="string"/> is equal to the current <see cref="StringSegment"/>; otherwise, <see langword="false" />.</returns>
-        /// <exception cref="ArgumentNullException">
-        /// <paramref name="text"/> is <see langword="null" />.
-        /// </exception>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public bool Equals(string text, StringComparison comparisonType)
+        public bool Equals([NotNullWhen(true)] string? text, StringComparison comparisonType)
         {
             if (text == null)
             {
-                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.text);
+                return false;
             }
 
             if (!HasValue)
@@ -681,7 +680,8 @@ private static void CheckStringComparison(StringComparison comparisonType)
 
         // Methods that do no return (i.e. throw) are not inlined
         // https://github.com/dotnet/coreclr/pull/6103
-        private static void ThrowInvalidArguments(string buffer, int offset, int length)
+        [DoesNotReturn]
+        private static void ThrowInvalidArguments(string? buffer, int offset, int length)
         {
             // Only have single throw in method so is marked as "does not return" and isn't inlined to caller
             throw GetInvalidArgumentsException();
@@ -707,6 +707,7 @@ Exception GetInvalidArgumentsException()
             }
         }
 
+        [DoesNotReturn]
         private void ThrowInvalidArguments(int offset, int length, ExceptionArgument offsetOrStart)
         {
             throw GetInvalidArgumentsException(HasValue);
@@ -733,7 +734,7 @@ Exception GetInvalidArgumentsException(bool hasValue)
         }
 
         /// <inheritdoc />
-        bool IEquatable<string>.Equals(string other)
+        bool IEquatable<string>.Equals(string? other)
         {
             // Explicit interface implementation for IEquatable<string> because
             // the interface's Equals method allows null strings, which we return