PR feedback

src/Compilers/Core/Portable/Collections/SmallDictionary.cs

@@ -38,7 +38,8 @@ internal sealed class SmallDictionary<K, V> : IEnumerable<KeyValuePair<K, V>>
         private AvlNode? _root;
         public readonly IEqualityComparer<K> Comparer;
 
-        public static readonly SmallDictionary<K, V> Empty = new SmallDictionary<K, V>(EqualityComparer<K>.Default);
+        // https://github.com/dotnet/roslyn/issues/40344
+        public static readonly SmallDictionary<K, V> Empty = new SmallDictionary<K, V>(null!);
 
         public SmallDictionary() : this(EqualityComparer<K>.Default) { }
 
@@ -71,7 +72,7 @@ public bool TryGetValue(K key, [MaybeNullWhen(returnValue: false)] out V value)
         {
             if (_root != null)
             {
-                return TryGetValue(GetHashCode(key), key, out value);
+                return TryGetValue(GetHashCode(key), key, out value!);
             }
 
             value = default!;
@@ -88,7 +89,7 @@ public void Add(K key, V value)
             get
             {
                 V value;
-                if (!TryGetValue(key, out value))
+                if (!TryGetValue(key, out value!))
                 {
                     throw new KeyNotFoundException($"Could not find key {key}");
                 }
@@ -105,7 +106,7 @@ public void Add(K key, V value)
         public bool ContainsKey(K key)
         {
             V value;
-            return TryGetValue(key, out value);
+            return TryGetValue(key, out value!);
         }
 
         [Conditional("DEBUG")]
@@ -228,7 +229,7 @@ private bool TryGetValue(int hashCode, K key, [MaybeNullWhen(returnValue: false)
                 return true;
             }
 
-            return GetFromList(b.Next, key, out value);
+            return GetFromList(b.Next, key, out value!);
         }
 
         private bool GetFromList(Node? next, K key, [MaybeNullWhen(returnValue: false)] out V value)
@@ -527,7 +528,7 @@ public Enumerator(SmallDictionary<K, V> dict)
                         // left == right only if both are nulls
                         if (root.Left == root.Right)
                         {
-                            _next = dict._root;
+                            _next = root;
                         }
                         else
                         {
@@ -645,7 +646,7 @@ public Enumerator(SmallDictionary<K, V> dict)
                     // left == right only if both are nulls
                     if (root.Left == root.Right)
                     {
-                        _next = dict._root;
+                        _next = root;
                     }
                     else
                     {

src/Compilers/Core/Portable/ConstantValue.cs

@@ -31,7 +31,7 @@ internal enum ConstantValueTypeDiscriminator : byte
         DateTime,
     }
 
-    internal abstract partial class ConstantValue : IEquatable<ConstantValue>
+    internal abstract partial class ConstantValue : IEquatable<ConstantValue?>
     {
         public abstract ConstantValueTypeDiscriminator Discriminator { get; }
         internal abstract SpecialType SpecialType { get; }

src/Compilers/Core/Portable/Diagnostic/Diagnostic.DiagnosticWithProgrammaticSuppression.cs

@@ -40,10 +40,10 @@ public override string Id
                 get { return Descriptor.Id; }
             }
 
-            public override string? GetMessage(IFormatProvider? formatProvider = null)
+            public override string GetMessage(IFormatProvider? formatProvider = null)
                 => _originalUnsuppressedDiagnostic.GetMessage(formatProvider);
 
-            internal override IReadOnlyList<object>? Arguments
+            internal override IReadOnlyList<object?>? Arguments
             {
                 get { return _originalUnsuppressedDiagnostic.Arguments; }
             }

src/Compilers/Core/Portable/Diagnostic/Diagnostic.cs

@@ -36,7 +36,7 @@ public abstract partial class Diagnostic : IEquatable<Diagnostic?>, IFormattable
         public static Diagnostic Create(
             DiagnosticDescriptor descriptor,
             Location location,
-            params object[] messageArgs)
+            params object?[] messageArgs)
         {
             return Create(descriptor, location, null, null, messageArgs);
         }
@@ -57,7 +57,7 @@ public abstract partial class Diagnostic : IEquatable<Diagnostic?>, IFormattable
             DiagnosticDescriptor descriptor,
             Location location,
             ImmutableDictionary<string, string>? properties,
-            params object[]? messageArgs)
+            params object?[] messageArgs)
         {
             return Create(descriptor, location, null, properties, messageArgs);
         }
@@ -78,7 +78,7 @@ public abstract partial class Diagnostic : IEquatable<Diagnostic?>, IFormattable
             DiagnosticDescriptor descriptor,
             Location location,
             IEnumerable<Location>? additionalLocations,
-            params object[]? messageArgs)
+            params object?[] messageArgs)
         {
             return Create(descriptor, location, additionalLocations, properties: null, messageArgs: messageArgs);
         }
@@ -105,7 +105,7 @@ public abstract partial class Diagnostic : IEquatable<Diagnostic?>, IFormattable
             Location location,
             IEnumerable<Location>? additionalLocations,
             ImmutableDictionary<string, string>? properties,
-            params object[]? messageArgs)
+            params object?[] messageArgs)
         {
             return Create(descriptor, location, effectiveSeverity: descriptor.DefaultSeverity, additionalLocations, properties, messageArgs);
         }
@@ -134,7 +134,7 @@ public abstract partial class Diagnostic : IEquatable<Diagnostic?>, IFormattable
             DiagnosticSeverity effectiveSeverity,
             IEnumerable<Location>? additionalLocations,
             ImmutableDictionary<string, string>? properties,
-            params object[]? messageArgs)
+            params object?[] messageArgs)
         {
             if (descriptor == null)
             {
@@ -300,7 +300,7 @@ internal static Diagnostic Create(DiagnosticInfo info)
         /// <summary>
         /// Get the culture specific text of the message.
         /// </summary>
-        public abstract string? GetMessage(IFormatProvider? formatProvider = null);
+        public abstract string GetMessage(IFormatProvider? formatProvider = null);
 
         /// <summary>
         /// Gets the default <see cref="DiagnosticSeverity"/> of the diagnostic's <see cref="DiagnosticDescriptor"/>.
@@ -466,9 +466,9 @@ internal Diagnostic WithProgrammaticSuppression(ProgrammaticSuppressionInfo prog
         // compatibility
         internal virtual int Code { get { return 0; } }
 
-        internal virtual IReadOnlyList<object>? Arguments
+        internal virtual IReadOnlyList<object?>? Arguments
         {
-            get { return SpecializedCollections.EmptyReadOnlyList<object>(); }
+            get { return SpecializedCollections.EmptyReadOnlyList<object?>(); }
         }
 
         /// <summary>

src/Compilers/Core/Portable/Diagnostic/Diagnostic_SimpleDiagnostic.cs

@@ -23,7 +23,7 @@ internal sealed class SimpleDiagnostic : Diagnostic
             private readonly int _warningLevel;
             private readonly Location _location;
             private readonly IReadOnlyList<Location> _additionalLocations;
-            private readonly object[] _messageArgs;
+            private readonly object?[] _messageArgs;
             private readonly ImmutableDictionary<string, string> _properties;
             private readonly bool _isSuppressed;
 
@@ -33,7 +33,7 @@ internal sealed class SimpleDiagnostic : Diagnostic
                 int warningLevel,
                 Location location,
                 IEnumerable<Location>? additionalLocations,
-                object[]? messageArgs,
+                object?[]? messageArgs,
                 ImmutableDictionary<string, string>? properties,
                 bool isSuppressed)
             {
@@ -48,7 +48,7 @@ internal sealed class SimpleDiagnostic : Diagnostic
                 _warningLevel = warningLevel;
                 _location = location ?? Location.None;
                 _additionalLocations = additionalLocations?.ToImmutableArray() ?? SpecializedCollections.EmptyReadOnlyList<Location>();
-                _messageArgs = messageArgs ?? Array.Empty<object>();
+                _messageArgs = messageArgs ?? Array.Empty<object?>();
                 _properties = properties ?? ImmutableDictionary<string, string>.Empty;
                 _isSuppressed = isSuppressed;
             }
@@ -59,7 +59,7 @@ internal sealed class SimpleDiagnostic : Diagnostic
                 int warningLevel,
                 Location location,
                 IEnumerable<Location>? additionalLocations,
-                object[]? messageArgs,
+                object?[]? messageArgs,
                 ImmutableDictionary<string, string>? properties,
                 bool isSuppressed = false)
             {
@@ -87,7 +87,7 @@ public override string Id
                 get { return _descriptor.Id; }
             }
 
-            public override string? GetMessage(IFormatProvider? formatProvider = null)
+            public override string GetMessage(IFormatProvider? formatProvider = null)
             {
                 if (_messageArgs.Length == 0)
                 {
@@ -107,7 +107,7 @@ public override string Id
                 }
             }
 
-            internal override IReadOnlyList<object> Arguments
+            internal override IReadOnlyList<object?> Arguments
             {
                 get { return _messageArgs; }
             }

src/Compilers/Core/Portable/Diagnostic/ExternalFileLocation.cs

@@ -11,7 +11,7 @@ namespace Microsoft.CodeAnalysis
     /// <summary>
     /// A program location in source code.
     /// </summary>
-    internal sealed class ExternalFileLocation : Location, IEquatable<ExternalFileLocation>
+    internal sealed class ExternalFileLocation : Location, IEquatable<ExternalFileLocation?>
     {
         private readonly TextSpan _sourceSpan;
         private readonly FileLinePositionSpan _lineSpan;

src/Compilers/Core/Portable/Diagnostic/LocalizableString.cs

@@ -21,7 +21,7 @@ public abstract partial class LocalizableString : IFormattable, IEquatable<Local
         /// <summary>
         /// Formats the value of the current instance using the optionally specified format. 
         /// </summary>
-        public string? ToString(IFormatProvider? formatProvider)
+        public string ToString(IFormatProvider? formatProvider)
         {
             try
             {
@@ -90,7 +90,7 @@ public bool Equals(LocalizableString? other)
         /// Provides the implementation of ToString. ToString will provide a default value
         /// if this method throws an exception.
         /// </summary>
-        protected abstract string? GetText(IFormatProvider? formatProvider);
+        protected abstract string GetText(IFormatProvider? formatProvider);
 
         /// <summary>
         /// Provides the implementation of GetHashCode. GetHashCode will provide a default value

src/Compilers/Core/Portable/InternalUtilities/TextKeyedCache.cs

@@ -113,8 +113,7 @@ public void Free()
 
         #endregion // Poolable
 
-        [return: MaybeNull]
-        internal T FindItem(char[] chars, int start, int len, int hashCode)
+        internal T? FindItem(char[] chars, int start, int len, int hashCode)
         {
             // get direct element reference to avoid extra range checks
             ref var localSlot = ref _localTable[LocalIdxFromHash(hashCode)];

src/Compilers/Core/Portable/TreeDumper.cs

@@ -111,7 +111,7 @@ private void DoDumpCompact(TreeDumperNode node, string indent)
         public static string DumpXML(TreeDumperNode root, string? indent = null)
         {
             var dumper = new TreeDumper();
-            dumper.DoDumpXML(root, string.Empty, string.IsNullOrEmpty(indent) ? string.Empty : indent!);
+            dumper.DoDumpXML(root, string.Empty, indent ?? string.Empty);
             return dumper._sb.ToString();
         }
 
@@ -216,7 +216,7 @@ public TreeDumperNode(string text, object? value, IEnumerable<TreeDumperNode>? c
 
         public TreeDumperNode(string text) : this(text, null, null) { }
         public object? Value { get; }
-        public string? Text { get; }
+        public string Text { get; }
         public IEnumerable<TreeDumperNode> Children { get; }
         public TreeDumperNode this[string child]
         {

src/Features/Core/Portable/EditAndContinue/EditSession.cs

@@ -346,7 +346,7 @@ internal async Task<ImmutableArray<ActiveStatementExceptionRegions>> GetBaseActi
 
                     case CommittedSolution.DocumentState.OutOfSync:
                         var descriptor = EditAndContinueDiagnosticDescriptors.GetDescriptor(EditAndContinueErrorCode.DocumentIsOutOfSyncWithDebuggee);
-                        outOfSyncDiagnostics.Add(Diagnostic.Create(descriptor, Location.Create(document.FilePath!, textSpan: default, lineSpan: default), new[] { document.FilePath! }));
+                        outOfSyncDiagnostics.Add(Diagnostic.Create(descriptor, Location.Create(document.FilePath!, textSpan: default, lineSpan: default), new[] { document.FilePath }));
                         continue;
 
                     default:

src/Workspaces/Core/Portable/Shared/Extensions/LocationExtensions.cs

@@ -3,22 +3,29 @@
 #nullable enable
 
 using System.Threading;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.Shared.Extensions
 {
     internal static class LocationExtensions
     {
+        public static SyntaxTree GetSourceTreeOrThrow(this Location location)
+        {
+            Contract.ThrowIfNull(location.SourceTree);
+            return location.SourceTree;
+        }
+
         public static SyntaxToken FindToken(this Location location, CancellationToken cancellationToken)
-            => location.SourceTree!.GetRoot(cancellationToken).FindToken(location.SourceSpan.Start);
+            => location.GetSourceTreeOrThrow().GetRoot(cancellationToken).FindToken(location.SourceSpan.Start);
 
         public static SyntaxNode FindNode(this Location location, CancellationToken cancellationToken)
-            => location.SourceTree!.GetRoot(cancellationToken).FindNode(location.SourceSpan);
+            => location.GetSourceTreeOrThrow().GetRoot(cancellationToken).FindNode(location.SourceSpan);
 
         public static SyntaxNode FindNode(this Location location, bool getInnermostNodeForTie, CancellationToken cancellationToken)
-            => location.SourceTree!.GetRoot(cancellationToken).FindNode(location.SourceSpan, getInnermostNodeForTie: getInnermostNodeForTie);
+            => location.GetSourceTreeOrThrow().GetRoot(cancellationToken).FindNode(location.SourceSpan, getInnermostNodeForTie: getInnermostNodeForTie);
 
         public static SyntaxNode FindNode(this Location location, bool findInsideTrivia, bool getInnermostNodeForTie, CancellationToken cancellationToken)
-            => location.SourceTree!.GetRoot(cancellationToken).FindNode(location.SourceSpan, findInsideTrivia, getInnermostNodeForTie);
+            => location.GetSourceTreeOrThrow().GetRoot(cancellationToken).FindNode(location.SourceSpan, findInsideTrivia, getInnermostNodeForTie);
 
         public static bool IsVisibleSourceLocation(this Location loc)
         {