Annotate more compiler internal types

src/Compilers/Core/Portable/Binding/AbstractLookupSymbolsInfo.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -15,12 +17,12 @@ public struct ArityEnumerator : IEnumerator<int>
         {
             private int _current;
             private readonly int _low32bits;
-            private int[] _arities;
+            private int[]? _arities;
 
             private const int resetValue = -1;
             private const int reachedEndValue = int.MaxValue;
 
-            internal ArityEnumerator(int bitVector, HashSet<int> arities)
+            internal ArityEnumerator(int bitVector, HashSet<int>? arities)
             {
                 _current = resetValue;
                 _low32bits = bitVector;
@@ -39,7 +41,7 @@ internal ArityEnumerator(int bitVector, HashSet<int> arities)
 
             public void Dispose() => _arities = null;
 
-            object System.Collections.IEnumerator.Current => _current;
+            object? System.Collections.IEnumerator.Current => _current;
 
             public bool MoveNext()
             {
@@ -118,7 +120,7 @@ private struct UniqueSymbolOrArities : IArityEnumerable
             //   Then arityBitVectorOrUniqueArity is interpreted as a bitvector
             //   of arities for arities from zero to 31 and the HashSet contains
             //   arities of 32 or more.
-            private object _uniqueSymbolOrArities;
+            private object? _uniqueSymbolOrArities;
             private int _arityBitVectorOrUniqueArity;
 
             public UniqueSymbolOrArities(int arity, TSymbol uniqueSymbol)
@@ -181,12 +183,14 @@ private void AddArity(int arity)
                 hashSet.Add(arity);
             }
 
-            public void GetUniqueSymbolOrArities(out IArityEnumerable arities, out TSymbol uniqueSymbol)
+            public void GetUniqueSymbolOrArities(out IArityEnumerable? arities, out TSymbol? uniqueSymbol)
             {
                 if (this.HasUniqueSymbol)
                 {
                     arities = null;
+#nullable disable // Can '_uniqueSymbolOrArities' be null? https://github.com/dotnet/roslyn/issues/39166
                     uniqueSymbol = (TSymbol)_uniqueSymbolOrArities;
+#nullable enable
                 }
                 else
                 {
@@ -198,7 +202,7 @@ public void GetUniqueSymbolOrArities(out IArityEnumerable arities, out TSymbol u
             public ArityEnumerator GetEnumerator()
             {
                 Debug.Assert(!this.HasUniqueSymbol);
-                return new ArityEnumerator(_arityBitVectorOrUniqueArity, (HashSet<int>)_uniqueSymbolOrArities);
+                return new ArityEnumerator(_arityBitVectorOrUniqueArity, (HashSet<int>?)_uniqueSymbolOrArities);
             }
 
             public int Count
@@ -207,7 +211,7 @@ public int Count
                 {
                     Debug.Assert(!this.HasUniqueSymbol);
                     int count = BitArithmeticUtilities.CountBits(_arityBitVectorOrUniqueArity);
-                    var set = (HashSet<int>)_uniqueSymbolOrArities;
+                    var set = (HashSet<int>?)_uniqueSymbolOrArities;
                     if (set != null)
                     {
                         count += set.Count;
@@ -218,13 +222,13 @@ public int Count
             }
 
 #if DEBUG
-            internal TSymbol UniqueSymbol => _uniqueSymbolOrArities as TSymbol;
+            internal TSymbol? UniqueSymbol => _uniqueSymbolOrArities as TSymbol;
 #endif
         }
 
         private readonly IEqualityComparer<string> _comparer;
         private readonly Dictionary<string, UniqueSymbolOrArities> _nameMap;
-        internal string FilterName { get; set; }
+        internal string? FilterName { get; set; }
 
         protected AbstractLookupSymbolsInfo(IEqualityComparer<string> comparer)
         {
@@ -275,8 +279,8 @@ public void AddSymbol(TSymbol symbol, string name, int arity)
         /// <returns></returns>
         public bool TryGetAritiesAndUniqueSymbol(
             string name,
-            out IArityEnumerable arities,
-            out TSymbol uniqueSymbol)
+            out IArityEnumerable? arities,
+            out TSymbol? uniqueSymbol)
         {
             Debug.Assert(CanBeAdded(name));
 

src/Compilers/Core/Portable/CodeGen/ArrayMembers.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using Microsoft.CodeAnalysis.PooledObjects;
 using Roslyn.Utilities;
 using System;
@@ -324,14 +326,14 @@ protected virtual ImmutableArray<ArrayMethodParameterInfo> MakeParameters()
 
         public bool IsGeneric => false;
 
-        public Cci.IMethodDefinition GetResolvedMethod(EmitContext context) => null;
+        public Cci.IMethodDefinition? GetResolvedMethod(EmitContext context) => null;
 
         public ImmutableArray<Cci.IParameterTypeInformation> ExtraParameters
             => ImmutableArray<Cci.IParameterTypeInformation>.Empty;
 
-        public Cci.IGenericMethodInstanceReference AsGenericMethodInstanceReference => null;
+        public Cci.IGenericMethodInstanceReference? AsGenericMethodInstanceReference => null;
 
-        public Cci.ISpecializedMethodReference AsSpecializedMethodReference => null;
+        public Cci.ISpecializedMethodReference? AsSpecializedMethodReference => null;
 
         public Cci.CallingConvention CallingConvention => Cci.CallingConvention.HasThis;
 
@@ -356,7 +358,7 @@ public Cci.ITypeReference GetContainingType(EmitContext context)
         public void Dispatch(Cci.MetadataVisitor visitor)
             => visitor.Visit(this);
 
-        public Cci.IDefinition AsDefinition(EmitContext context)
+        public Cci.IDefinition? AsDefinition(EmitContext context)
             => null;
 
         public override string ToString()

src/Compilers/Core/Portable/CodeGen/ClosureDebugInfo.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Diagnostics;
 using Roslyn.Utilities;
@@ -24,7 +26,7 @@ public bool Equals(ClosureDebugInfo other)
                    ClosureId.Equals(other.ClosureId);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is ClosureDebugInfo && Equals((ClosureDebugInfo)obj);
         }

src/Compilers/Core/Portable/CodeGen/CompilationTestData.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using Microsoft.CodeAnalysis.Emit;
 using Microsoft.DiaSymReader;
 using System;
@@ -29,16 +31,16 @@ public MethodData(ILBuilder ilBuilder, IMethodSymbol method)
         public readonly ConcurrentDictionary<IMethodSymbol, MethodData> Methods = new ConcurrentDictionary<IMethodSymbol, MethodData>();
 
         // The emitted module.
-        public CommonPEModuleBuilder Module;
+        public CommonPEModuleBuilder? Module;
 
-        public Func<ISymWriterMetadataProvider, SymUnmanagedWriter> SymWriterFactory;
+        public Func<ISymWriterMetadataProvider, SymUnmanagedWriter>? SymWriterFactory;
 
         public ILBuilder GetIL(Func<IMethodSymbol, bool> predicate)
         {
             return Methods.Single(p => predicate(p.Key)).Value.ILBuilder;
         }
 
-        private ImmutableDictionary<string, MethodData> _lazyMethodsByName;
+        private ImmutableDictionary<string, MethodData>? _lazyMethodsByName;
 
         // Returns map indexed by name for those methods that have a unique name.
         public ImmutableDictionary<string, MethodData> GetMethodsByName()

src/Compilers/Core/Portable/CodeGen/DebugDocumentProvider.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  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.CodeAnalysis.CodeGen
 {
     internal delegate Cci.DebugSourceDocument DebugDocumentProvider(string path, string basePath);

src/Compilers/Core/Portable/CodeGen/DebugId.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Diagnostics;
 using Roslyn.Utilities;
@@ -43,7 +45,7 @@ public bool Equals(DebugId other)
                 && this.Generation == other.Generation;
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is DebugId && Equals((DebugId)obj);
         }

src/Compilers/Core/Portable/CodeGen/DynamicAnalysisMethodBodyData.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System.Collections.Immutable;
 using System.Diagnostics;
 

src/Compilers/Core/Portable/CodeGen/EmitState.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Diagnostics;
 using Microsoft.CodeAnalysis.Text;

src/Compilers/Core/Portable/CodeGen/ILBuilderConversions.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Diagnostics;
 using System.Reflection.Metadata;

src/Compilers/Core/Portable/CodeGen/ILBuilderEmit.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
@@ -240,7 +242,7 @@ internal void EmitStringSwitchJumpTable(
             KeyValuePair<ConstantValue, object>[] caseLabels,
             object fallThroughLabel,
             LocalOrParameter key,
-            LocalDefinition keyHash,
+            LocalDefinition? keyHash,
             SwitchStringJumpTableEmitter.EmitStringCompareAndBranch emitStringCondBranchDelegate,
             SwitchStringJumpTableEmitter.GetStringHashCode computeStringHashcodeDelegate)
         {

src/Compilers/Core/Portable/CodeGen/ILEmitStyle.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  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.CodeAnalysis.CodeGen
 {
     internal enum ILEmitStyle : byte

src/Compilers/Core/Portable/CodeGen/ILOpCodeExtensions.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Diagnostics;
 using System.Reflection.Metadata;

src/Compilers/Core/Portable/CodeGen/ITokenDeferral.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis.CodeGen

src/Compilers/Core/Portable/CodeGen/ItemTokenMap.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using Microsoft.CodeAnalysis.PooledObjects;

src/Compilers/Core/Portable/CodeGen/LabelInfo.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using Microsoft.CodeAnalysis.Text;
 
 namespace Microsoft.CodeAnalysis.CodeGen
@@ -17,7 +19,7 @@ private struct LabelInfo
             //if a label is marked before any branches to the label have been seen
             //the stack is considered to be 0.
             internal readonly int stack;
-            internal readonly BasicBlock bb;
+            internal readonly BasicBlock? bb;
 
             /// <summary>
             /// Sometimes we need to know if a label is targeted by conditional branches.
@@ -37,14 +39,14 @@ internal LabelInfo(int stack, bool targetOfConditionalBranches)
             /// <summary>
             /// Used when label is marked to the code.
             /// </summary>
-            internal LabelInfo(BasicBlock bb, int stack, bool targetOfConditionalBranches)
+            internal LabelInfo(BasicBlock? bb, int stack, bool targetOfConditionalBranches)
             {
                 this.stack = stack;
                 this.bb = bb;
                 this.targetOfConditionalBranches = targetOfConditionalBranches;
             }
 
-            internal LabelInfo WithNewTarget(BasicBlock bb)
+            internal LabelInfo WithNewTarget(BasicBlock? bb)
             {
                 return new LabelInfo(bb, this.stack, this.targetOfConditionalBranches);
             }

src/Compilers/Core/Portable/CodeGen/LambdaDebugInfo.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Diagnostics;
 using Roslyn.Utilities;
@@ -49,7 +51,7 @@ public bool Equals(LambdaDebugInfo other)
                 && LambdaId.Equals(other.LambdaId);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is LambdaDebugInfo && Equals((LambdaDebugInfo)obj);
         }

src/Compilers/Core/Portable/CodeGen/LocalConstantDefinition.cs

@@ -1,9 +1,12 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Reflection.Metadata;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CodeGen
 {
@@ -20,8 +23,8 @@ public LocalConstantDefinition(
             ImmutableArray<bool> dynamicTransformFlags,
             ImmutableArray<string> tupleElementNames)
         {
-            Debug.Assert(!string.IsNullOrEmpty(name));
-            Debug.Assert(compileTimeValue != null);
+            RoslynDebug.Assert(!RoslynString.IsNullOrEmpty(name));
+            RoslynDebug.Assert(compileTimeValue != null);
 
             Name = name;
             Location = location;
@@ -59,7 +62,7 @@ public ImmutableArray<Cci.ICustomModifier> CustomModifiers
 
         public int SlotIndex => -1;
 
-        public byte[] Signature => null;
+        public byte[]? Signature => null;
 
         public LocalSlotDebugInfo SlotInfo
             => new LocalSlotDebugInfo(SynthesizedLocalKind.UserDefined, LocalDebugId.None);

src/Compilers/Core/Portable/CodeGen/LocalDebugId.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Diagnostics;
 using Roslyn.Utilities;
@@ -72,7 +74,7 @@ public override int GetHashCode()
             return Hash.Combine(SyntaxOffset, Ordinal);
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is LocalDebugId && Equals((LocalDebugId)obj);
         }