Add annotations for symbol-related types and interfaces

src/Compilers/CSharp/Portable/Binder/Semantics/SemanticFacts.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 Microsoft.CodeAnalysis.CSharp.Symbols;
@@ -19,7 +21,7 @@ internal partial class Symbol
         public static bool IsSymbolAccessible(
             Symbol symbol,
             NamedTypeSymbol within,
-            NamedTypeSymbol throughTypeOpt = null)
+            NamedTypeSymbol? throughTypeOpt = null)
         {
             if ((object)symbol == null)
             {
@@ -31,7 +33,7 @@ public static bool IsSymbolAccessible(
                 throw new ArgumentNullException(nameof(within));
             }
 
-            HashSet<DiagnosticInfo> useSiteDiagnostics = null;
+            HashSet<DiagnosticInfo>? useSiteDiagnostics = null;
             return AccessCheck.IsSymbolAccessible(
                 symbol,
                 within,
@@ -56,7 +58,7 @@ public static bool IsSymbolAccessible(
                 throw new ArgumentNullException(nameof(within));
             }
 
-            HashSet<DiagnosticInfo> useSiteDiagnostics = null;
+            HashSet<DiagnosticInfo>? useSiteDiagnostics = null;
             return AccessCheck.IsSymbolAccessible(symbol, within, ref useSiteDiagnostics);
         }
     }

src/Compilers/CSharp/Portable/Emitter/Model/ArrayTypeSymbolAdapter.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.Generic;
 using System.Collections.Immutable;
 using System.Reflection.Metadata;
@@ -52,16 +54,16 @@ void Cci.IReference.Dispatch(Cci.MetadataVisitor visitor)
         TypeDefinitionHandle Cci.ITypeReference.TypeDef => default(TypeDefinitionHandle);
         Cci.PrimitiveTypeCode Cci.ITypeReference.TypeCode => Cci.PrimitiveTypeCode.NotPrimitive;
 
-        Cci.ITypeDefinition Cci.ITypeReference.GetResolvedType(EmitContext context) => null;
-        Cci.IGenericMethodParameterReference Cci.ITypeReference.AsGenericMethodParameterReference => null;
-        Cci.IGenericTypeInstanceReference Cci.ITypeReference.AsGenericTypeInstanceReference => null;
-        Cci.IGenericTypeParameterReference Cci.ITypeReference.AsGenericTypeParameterReference => null;
-        Cci.INamespaceTypeDefinition Cci.ITypeReference.AsNamespaceTypeDefinition(EmitContext context) => null;
-        Cci.INamespaceTypeReference Cci.ITypeReference.AsNamespaceTypeReference => null;
-        Cci.INestedTypeDefinition Cci.ITypeReference.AsNestedTypeDefinition(EmitContext context) => null;
-        Cci.INestedTypeReference Cci.ITypeReference.AsNestedTypeReference => null;
-        Cci.ISpecializedNestedTypeReference Cci.ITypeReference.AsSpecializedNestedTypeReference => null;
-        Cci.ITypeDefinition Cci.ITypeReference.AsTypeDefinition(EmitContext context) => null;
-        Cci.IDefinition Cci.IReference.AsDefinition(EmitContext context) => null;
+        Cci.ITypeDefinition? Cci.ITypeReference.GetResolvedType(EmitContext context) => null;
+        Cci.IGenericMethodParameterReference? Cci.ITypeReference.AsGenericMethodParameterReference => null;
+        Cci.IGenericTypeInstanceReference? Cci.ITypeReference.AsGenericTypeInstanceReference => null;
+        Cci.IGenericTypeParameterReference? Cci.ITypeReference.AsGenericTypeParameterReference => null;
+        Cci.INamespaceTypeDefinition? Cci.ITypeReference.AsNamespaceTypeDefinition(EmitContext context) => null;
+        Cci.INamespaceTypeReference? Cci.ITypeReference.AsNamespaceTypeReference => null;
+        Cci.INestedTypeDefinition? Cci.ITypeReference.AsNestedTypeDefinition(EmitContext context) => null;
+        Cci.INestedTypeReference? Cci.ITypeReference.AsNestedTypeReference => null;
+        Cci.ISpecializedNestedTypeReference? Cci.ITypeReference.AsSpecializedNestedTypeReference => null;
+        Cci.ITypeDefinition? Cci.ITypeReference.AsTypeDefinition(EmitContext context) => null;
+        Cci.IDefinition? Cci.IReference.AsDefinition(EmitContext context) => null;
     }
 }

src/Compilers/CSharp/Portable/Emitter/Model/DynamicTypeSymbolAdapter.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.Reflection.Metadata;
 using Microsoft.CodeAnalysis.CSharp.Emit;
@@ -23,7 +25,7 @@ bool Cci.ITypeReference.IsValueType
             get { return false; }
         }
 
-        Cci.ITypeDefinition Cci.ITypeReference.GetResolvedType(EmitContext context)
+        Cci.ITypeDefinition? Cci.ITypeReference.GetResolvedType(EmitContext context)
         {
             // dynamic can't be used in mscorlib, so the containing module is never the module being built
             return null;
@@ -39,17 +41,17 @@ TypeDefinitionHandle Cci.ITypeReference.TypeDef
             get { return default(TypeDefinitionHandle); }
         }
 
-        Cci.IGenericMethodParameterReference Cci.ITypeReference.AsGenericMethodParameterReference
+        Cci.IGenericMethodParameterReference? Cci.ITypeReference.AsGenericMethodParameterReference
         {
             get { return null; }
         }
 
-        Cci.IGenericTypeInstanceReference Cci.ITypeReference.AsGenericTypeInstanceReference
+        Cci.IGenericTypeInstanceReference? Cci.ITypeReference.AsGenericTypeInstanceReference
         {
             get { return null; }
         }
 
-        Cci.IGenericTypeParameterReference Cci.ITypeReference.AsGenericTypeParameterReference
+        Cci.IGenericTypeParameterReference? Cci.ITypeReference.AsGenericTypeParameterReference
         {
             get { return null; }
         }
@@ -59,28 +61,28 @@ Cci.INamespaceTypeReference Cci.ITypeReference.AsNamespaceTypeReference
             get { return this; }
         }
 
-        Cci.INamespaceTypeDefinition Cci.ITypeReference.AsNamespaceTypeDefinition(EmitContext context)
+        Cci.INamespaceTypeDefinition? Cci.ITypeReference.AsNamespaceTypeDefinition(EmitContext context)
         {
             // dynamic can't be used in mscorlib, so the containing module is never the module being built
             return null;
         }
 
-        Cci.INestedTypeReference Cci.ITypeReference.AsNestedTypeReference
+        Cci.INestedTypeReference? Cci.ITypeReference.AsNestedTypeReference
         {
             get { return null; }
         }
 
-        Cci.INestedTypeDefinition Cci.ITypeReference.AsNestedTypeDefinition(EmitContext context)
+        Cci.INestedTypeDefinition? Cci.ITypeReference.AsNestedTypeDefinition(EmitContext context)
         {
             return null;
         }
 
-        Cci.ISpecializedNestedTypeReference Cci.ITypeReference.AsSpecializedNestedTypeReference
+        Cci.ISpecializedNestedTypeReference? Cci.ITypeReference.AsSpecializedNestedTypeReference
         {
             get { return null; }
         }
 
-        Cci.ITypeDefinition Cci.ITypeReference.AsTypeDefinition(EmitContext context)
+        Cci.ITypeDefinition? Cci.ITypeReference.AsTypeDefinition(EmitContext context)
         {
             // dynamic can't be used in mscorlib, so the containing module is never the module being built
             return null;
@@ -91,7 +93,7 @@ void Cci.IReference.Dispatch(Cci.MetadataVisitor visitor)
             throw ExceptionUtilities.Unreachable;
         }
 
-        Cci.IDefinition Cci.IReference.AsDefinition(EmitContext context)
+        Cci.IDefinition? Cci.IReference.AsDefinition(EmitContext context)
         {
             // dynamic can't be used in mscorlib, so the containing module is never the module being built
             return null;

src/Compilers/CSharp/Portable/Emitter/Model/EventSymbolAdapter.cs

@@ -1,10 +1,13 @@
 // 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.Generic;
 using System.Diagnostics;
 using Microsoft.Cci;
 using Microsoft.CodeAnalysis.CSharp.Emit;
 using Microsoft.CodeAnalysis.Emit;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CSharp.Symbols
 {
@@ -18,14 +21,14 @@ internal partial class EventSymbol :
             CheckDefinitionInvariant();
 
             var addMethod = this.AddMethod;
-            Debug.Assert((object)addMethod != null);
+            RoslynDebug.Assert((object?)addMethod != null);
             if (addMethod.ShouldInclude(context))
             {
                 yield return addMethod;
             }
 
             var removeMethod = this.RemoveMethod;
-            Debug.Assert((object)removeMethod != null);
+            RoslynDebug.Assert((object?)removeMethod != null);
             if (removeMethod.ShouldInclude(context))
             {
                 yield return removeMethod;
@@ -37,8 +40,8 @@ Cci.IMethodReference Cci.IEventDefinition.Adder
             get
             {
                 CheckDefinitionInvariant();
-                MethodSymbol addMethod = this.AddMethod;
-                Debug.Assert((object)addMethod != null);
+                MethodSymbol? addMethod = this.AddMethod;
+                RoslynDebug.Assert((object?)addMethod != null);
                 return addMethod;
             }
         }
@@ -48,8 +51,8 @@ Cci.IMethodReference Cci.IEventDefinition.Remover
             get
             {
                 CheckDefinitionInvariant();
-                MethodSymbol removeMethod = this.RemoveMethod;
-                Debug.Assert((object)removeMethod != null);
+                MethodSymbol? removeMethod = this.RemoveMethod;
+                RoslynDebug.Assert((object?)removeMethod != null);
                 return removeMethod;
             }
         }
@@ -81,7 +84,7 @@ bool Cci.IEventDefinition.IsSpecialName
             }
         }
 
-        Cci.IMethodReference Cci.IEventDefinition.Caller
+        Cci.IMethodReference? Cci.IEventDefinition.Caller
         {
             get
             {

src/Compilers/CSharp/Portable/Emitter/Model/FieldSymbolAdapter.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;
 using Microsoft.CodeAnalysis.CodeGen;
@@ -38,12 +40,12 @@ Cci.ITypeReference Cci.IFieldReference.GetType(EmitContext context)
             }
         }
 
-        Cci.IFieldDefinition Cci.IFieldReference.GetResolvedField(EmitContext context)
+        Cci.IFieldDefinition? Cci.IFieldReference.GetResolvedField(EmitContext context)
         {
             return ResolvedFieldImpl((PEModuleBuilder)context.Module);
         }
 
-        private Cci.IFieldDefinition ResolvedFieldImpl(PEModuleBuilder moduleBeingBuilt)
+        private Cci.IFieldDefinition? ResolvedFieldImpl(PEModuleBuilder moduleBeingBuilt)
         {
             Debug.Assert(this.IsDefinitionOrDistinct());
 
@@ -56,7 +58,7 @@ private Cci.IFieldDefinition ResolvedFieldImpl(PEModuleBuilder moduleBeingBuilt)
             return null;
         }
 
-        Cci.ISpecializedFieldReference Cci.IFieldReference.AsSpecializedFieldReference
+        Cci.ISpecializedFieldReference? Cci.IFieldReference.AsSpecializedFieldReference
         {
             get
             {
@@ -101,7 +103,7 @@ void Cci.IReference.Dispatch(Cci.MetadataVisitor visitor)
             }
         }
 
-        Cci.IDefinition Cci.IReference.AsDefinition(EmitContext context)
+        Cci.IDefinition? Cci.IReference.AsDefinition(EmitContext context)
         {
             PEModuleBuilder moduleBeingBuilt = (PEModuleBuilder)context.Module;
 
@@ -124,14 +126,14 @@ bool Cci.IFieldReference.IsContextualNamedEntity
             }
         }
 
-        MetadataConstant Cci.IFieldDefinition.GetCompileTimeValue(EmitContext context)
+        MetadataConstant? Cci.IFieldDefinition.GetCompileTimeValue(EmitContext context)
         {
             CheckDefinitionInvariant();
 
             return GetMetadataConstantValue(context);
         }
 
-        internal MetadataConstant GetMetadataConstantValue(EmitContext context)
+        internal MetadataConstant? GetMetadataConstantValue(EmitContext context)
         {
             // A constant field of type decimal is not treated as a compile time value in CLR,
             // so check if it is a metadata constant, not just a constant to exclude decimals.
@@ -233,7 +235,7 @@ internal virtual bool IsMarshalledExplicitly
             }
         }
 
-        Cci.IMarshallingInformation Cci.IFieldDefinition.MarshallingInformation
+        Cci.IMarshallingInformation? Cci.IFieldDefinition.MarshallingInformation
         {
             get
             {

src/Compilers/CSharp/Portable/Emitter/Model/NamespaceSymbolAdapter.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.CSharp.Symbols
 {
     internal partial class NamespaceSymbol : Cci.INamespace

src/Compilers/CSharp/Portable/Emitter/Model/ParameterSymbolAdapter.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.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
@@ -56,20 +58,20 @@ ushort Cci.IParameterListEntry.Index
         /// <summary>
         /// Gets constant value to be stored in metadata Constant table.
         /// </summary>
-        MetadataConstant Cci.IParameterDefinition.GetDefaultValue(EmitContext context)
+        MetadataConstant? Cci.IParameterDefinition.GetDefaultValue(EmitContext context)
         {
             CheckDefinitionInvariant();
             return this.GetMetadataConstantValue(context);
         }
 
-        internal MetadataConstant GetMetadataConstantValue(EmitContext context)
+        internal MetadataConstant? GetMetadataConstantValue(EmitContext context)
         {
             if (!HasMetadataConstantValue)
             {
                 return null;
             }
 
-            ConstantValue constant = this.ExplicitDefaultConstantValue;
+            ConstantValue constant = this.ExplicitDefaultConstantValue!;
             TypeSymbol type;
             if (constant.SpecialType != SpecialType.None)
             {
@@ -156,7 +158,7 @@ bool Cci.IParameterDefinition.IsOut
             }
         }
 
-        Cci.IMarshallingInformation Cci.IParameterDefinition.MarshallingInformation
+        Cci.IMarshallingInformation? Cci.IParameterDefinition.MarshallingInformation
         {
             get
             {
@@ -206,7 +208,7 @@ void Cci.IReference.Dispatch(Cci.MetadataVisitor visitor)
 #endif
         }
 
-        Cci.IDefinition Cci.IReference.AsDefinition(EmitContext context)
+        Cci.IDefinition? Cci.IReference.AsDefinition(EmitContext context)
         {
             Debug.Assert(this.IsDefinitionOrDistinct());