CR feedback on the boxing reducing change.

Couple more places where boxing can be avoided (changeset 1211849)

Src/Compilers/CSharp/Source/Emitter/Model/GenericTypeInstanceReference.cs

@@ -4,6 +4,7 @@
 using Microsoft.CodeAnalysis.CSharp.Symbols;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Text;
+using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis.CSharp.Emit
 {
@@ -23,14 +24,16 @@ public sealed override void Dispatch(Microsoft.Cci.MetadataVisitor visitor)
             visitor.Visit((Microsoft.Cci.IGenericTypeInstanceReference)this);
         }
 
-        IEnumerable<Microsoft.Cci.ITypeReference> Microsoft.Cci.IGenericTypeInstanceReference.GetGenericArguments(Microsoft.CodeAnalysis.Emit.Context context)
+        ImmutableArray<Microsoft.Cci.ITypeReference> Microsoft.Cci.IGenericTypeInstanceReference.GetGenericArguments(Microsoft.CodeAnalysis.Emit.Context context)
         {
             PEModuleBuilder moduleBeingBuilt = (PEModuleBuilder)context.Module;
-
+            var builder = ArrayBuilder<Microsoft.Cci.ITypeReference>.GetInstance();
             foreach (TypeSymbol type in UnderlyingNamedType.TypeArgumentsNoUseSiteDiagnostics)
             {
-                yield return moduleBeingBuilt.Translate(type, syntaxNodeOpt: (CSharpSyntaxNode)context.SyntaxNodeOpt, diagnostics: context.Diagnostics);
+                builder.Add(moduleBeingBuilt.Translate(type, syntaxNodeOpt: (CSharpSyntaxNode)context.SyntaxNodeOpt, diagnostics: context.Diagnostics));
             }
+
+            return builder.ToImmutableAndFree();
         }
 
         Microsoft.Cci.INamedTypeReference Microsoft.Cci.IGenericTypeInstanceReference.GenericType

Src/Compilers/CSharp/Source/Emitter/Model/NamedTypeSymbolAdapter.cs

@@ -877,17 +877,18 @@ Cci.TypeMemberVisibility Cci.ITypeDefinitionMember.Visibility
             }
         }
 
-        IEnumerable<Cci.ITypeReference> Cci.IGenericTypeInstanceReference.GetGenericArguments(Microsoft.CodeAnalysis.Emit.Context context)
+        ImmutableArray<Cci.ITypeReference> Cci.IGenericTypeInstanceReference.GetGenericArguments(Microsoft.CodeAnalysis.Emit.Context context)
         {
             PEModuleBuilder moduleBeingBuilt = (PEModuleBuilder)context.Module;
-
+            var builder = ArrayBuilder<Microsoft.Cci.ITypeReference>.GetInstance();
             Debug.Assert(((Cci.ITypeReference)this).AsGenericTypeInstanceReference != null);
             foreach (TypeSymbol type in this.TypeArgumentsNoUseSiteDiagnostics)
             {
-                yield return moduleBeingBuilt.Translate(type,
-                                                        syntaxNodeOpt: (CSharpSyntaxNode)context.SyntaxNodeOpt,
-                                                        diagnostics: context.Diagnostics);
+                builder.Add(moduleBeingBuilt.Translate(type, syntaxNodeOpt: (CSharpSyntaxNode)context.SyntaxNodeOpt, diagnostics: context.Diagnostics));
             }
+
+            return builder.ToImmutableAndFree();
+
         }
 
         Cci.INamedTypeReference Cci.IGenericTypeInstanceReference.GenericType

Src/Compilers/CSharp/Source/Emitter/Model/PEModuleBuilder.cs

@@ -1185,7 +1185,12 @@ private static bool MustBeWrapped(ParameterSymbol param)
 
         private ImmutableArray<Cci.IParameterTypeInformation> TranslateAll(ImmutableArray<ParameterSymbol> @params)
         {
-            return @params.SelectAsArray(param => CreateParameterTypeInformationWrapper(param));
+            var builder = ArrayBuilder<Cci.IParameterTypeInformation>.GetInstance();
+            foreach(var param in @params)
+            {
+                builder.Add(CreateParameterTypeInformationWrapper(param));
+            }
+            return builder.ToImmutableAndFree();
         }
 
         private Cci.IParameterTypeInformation CreateParameterTypeInformationWrapper(ParameterSymbol param)

Src/Compilers/CSharp/Source/Emitter/Model/SpecializedGenericNestedTypeInstanceReference.cs

@@ -4,6 +4,7 @@
 using Microsoft.CodeAnalysis.CSharp.Symbols;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Text;
+using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis.CSharp.Emit
 {
@@ -25,14 +26,17 @@ public sealed override void Dispatch(Microsoft.Cci.MetadataVisitor visitor)
             visitor.Visit((Microsoft.Cci.IGenericTypeInstanceReference)this);
         }
 
-        IEnumerable<Microsoft.Cci.ITypeReference> Microsoft.Cci.IGenericTypeInstanceReference.GetGenericArguments(Microsoft.CodeAnalysis.Emit.Context context)
+        ImmutableArray<Microsoft.Cci.ITypeReference> Microsoft.Cci.IGenericTypeInstanceReference.GetGenericArguments(Microsoft.CodeAnalysis.Emit.Context context)
         {
             PEModuleBuilder moduleBeingBuilt = (PEModuleBuilder)context.Module;
-
+            var builder = ArrayBuilder<Microsoft.Cci.ITypeReference>.GetInstance();
             foreach (TypeSymbol type in UnderlyingNamedType.TypeArgumentsNoUseSiteDiagnostics)
             {
-                yield return moduleBeingBuilt.Translate(type, syntaxNodeOpt: (CSharpSyntaxNode)context.SyntaxNodeOpt, diagnostics: context.Diagnostics);
+                builder.Add(moduleBeingBuilt.Translate(type, syntaxNodeOpt: (CSharpSyntaxNode)context.SyntaxNodeOpt, diagnostics: context.Diagnostics));
             }
+
+            return builder.ToImmutableAndFree();
+
         }
 
         Microsoft.Cci.INamedTypeReference Microsoft.Cci.IGenericTypeInstanceReference.GenericType

Src/Compilers/Core/Source/PEWriter/PeWriter.cs

@@ -1108,21 +1108,22 @@ private void CreateIndicesFor(ITypeDefinition typeDef, Queue<ITypeDefinition> ne
             return result;
         }
 
-        protected IEnumerable<IParameterDefinition> GetParametersToEmit(IMethodDefinition methodDef)
+        protected ImmutableArray<IParameterDefinition> GetParametersToEmit(IMethodDefinition methodDef)
         {
             if (methodDef.ParameterCount == 0 && !(methodDef.ReturnValueIsMarshalledExplicitly || IteratorHelper.EnumerableIsNotEmpty(methodDef.ReturnValueAttributes)))
             {
-                return SpecializedCollections.EmptyEnumerable<IParameterDefinition>();
+                return ImmutableArray<IParameterDefinition>.Empty;
             }
 
             return GetParametersToEmitCore(methodDef);
         }
 
-        private IEnumerable<IParameterDefinition> GetParametersToEmitCore(IMethodDefinition methodDef)
+        private ImmutableArray<IParameterDefinition> GetParametersToEmitCore(IMethodDefinition methodDef)
         {
+            var builder = ArrayBuilder<IParameterDefinition>.GetInstance();
             if (methodDef.ReturnValueIsMarshalledExplicitly || IteratorHelper.EnumerableIsNotEmpty(methodDef.ReturnValueAttributes))
             {
-                yield return new ReturnValueParameter(methodDef);
+                builder.Add(new ReturnValueParameter(methodDef));
             }
 
             foreach (IParameterDefinition parDef in methodDef.Parameters)
@@ -1133,9 +1134,11 @@ private IEnumerable<IParameterDefinition> GetParametersToEmitCore(IMethodDefinit
                     parDef.Name != String.Empty ||
                     IteratorHelper.EnumerableIsNotEmpty(parDef.GetAttributes(Context)))
                 {
-                    yield return parDef;
+                    builder.Add(parDef);
                 }
             }
+
+            return builder.ToImmutableAndFree();
         }
 
         private void CreateInitialAssemblyRefIndex()

Src/Compilers/Core/Source/PEWriter/Types.cs

@@ -237,7 +237,7 @@ internal interface IGenericTypeInstanceReference : ITypeReference
         /// <summary>
         /// The type arguments that were used to instantiate this.GenericType in order to create this type.
         /// </summary>
-        IEnumerable<ITypeReference> GetGenericArguments(Microsoft.CodeAnalysis.Emit.Context context);
+        ImmutableArray<ITypeReference> GetGenericArguments(Microsoft.CodeAnalysis.Emit.Context context);
         // ^ ensures result.GetEnumerator().MoveNext(); // The collection is always non empty.
 
         /// <summary>

Src/Compilers/VisualBasic/Source/Emit/GenericTypeInstanceReference.vb

@@ -2,8 +2,10 @@
 
 Imports System
 Imports System.Collections.Generic
+Imports System.Collections.Immutable
 Imports System.Linq
 Imports System.Text
+Imports Microsoft.Cci
 Imports Microsoft.CodeAnalysis.Text
 Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
@@ -26,11 +28,15 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Emit
             visitor.Visit(DirectCast(Me, Microsoft.Cci.IGenericTypeInstanceReference))
         End Sub
 
-        Private Function IGenericTypeInstanceReferenceGetGenericArguments(context As Microsoft.CodeAnalysis.Emit.Context) As IEnumerable(Of Microsoft.Cci.ITypeReference) Implements Microsoft.Cci.IGenericTypeInstanceReference.GetGenericArguments
+        Private Function IGenericTypeInstanceReferenceGetGenericArguments(context As Microsoft.CodeAnalysis.Emit.Context) As ImmutableArray(Of Microsoft.Cci.ITypeReference) Implements Microsoft.Cci.IGenericTypeInstanceReference.GetGenericArguments
             Dim moduleBeingBuilt As PEModuleBuilder = DirectCast(context.Module, PEModuleBuilder)
 
-            Return From type In m_UnderlyingNamedType.TypeArgumentsNoUseSiteDiagnostics
-                   Select moduleBeingBuilt.Translate(type, syntaxNodeOpt:=DirectCast(context.SyntaxNodeOpt, VisualBasicSyntaxNode), diagnostics:=context.Diagnostics)
+            Dim builder = ArrayBuilder(Of ITypeReference).GetInstance()
+            For Each t In m_UnderlyingNamedType.TypeArgumentsNoUseSiteDiagnostics
+                builder.Add(moduleBeingBuilt.Translate(t, syntaxNodeOpt:=DirectCast(context.SyntaxNodeOpt, VisualBasicSyntaxNode), diagnostics:=context.Diagnostics))
+            Next
+
+            Return builder.ToImmutableAndFree
         End Function
 
         Private ReadOnly Property IGenericTypeInstanceReferenceGenericType As Microsoft.Cci.INamedTypeReference Implements Microsoft.Cci.IGenericTypeInstanceReference.GenericType

Src/Compilers/VisualBasic/Source/Emit/NamedTypeSymbolAdapter.vb

@@ -855,12 +855,16 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
             End Get
         End Property
 
-        Private Function IGenericTypeInstanceReferenceGetGenericArguments(context As Microsoft.CodeAnalysis.Emit.Context) As IEnumerable(Of ITypeReference) Implements IGenericTypeInstanceReference.GetGenericArguments
+        Private Function IGenericTypeInstanceReferenceGetGenericArguments(context As Microsoft.CodeAnalysis.Emit.Context) As ImmutableArray(Of ITypeReference) Implements IGenericTypeInstanceReference.GetGenericArguments
             Dim moduleBeingBuilt As PEModuleBuilder = DirectCast(context.Module, PEModuleBuilder)
             Debug.Assert((DirectCast(Me, ITypeReference)).AsGenericTypeInstanceReference IsNot Nothing)
 
-            Return From type In Me.TypeArgumentsNoUseSiteDiagnostics
-                   Select moduleBeingBuilt.Translate(type, syntaxNodeOpt:=DirectCast(context.SyntaxNodeOpt, VisualBasicSyntaxNode), diagnostics:=context.Diagnostics)
+            Dim builder = ArrayBuilder(Of ITypeReference).GetInstance()
+            For Each t In Me.TypeArgumentsNoUseSiteDiagnostics
+                builder.Add(moduleBeingBuilt.Translate(t, syntaxNodeOpt:=DirectCast(context.SyntaxNodeOpt, VisualBasicSyntaxNode), diagnostics:=context.Diagnostics))
+            Next
+
+            Return builder.ToImmutableAndFree
         End Function
 
         Private ReadOnly Property IGenericTypeInstanceReferenceGenericType As INamedTypeReference Implements IGenericTypeInstanceReference.GenericType

Src/Compilers/VisualBasic/Source/Emit/SpecializedGenericNestedTypeInstanceReference.vb

@@ -2,8 +2,10 @@
 
 Imports System
 Imports System.Collections.Generic
+Imports System.Collections.Immutable
 Imports System.Linq
 Imports System.Text
+Imports Microsoft.Cci
 Imports Microsoft.CodeAnalysis.Text
 Imports Microsoft.CodeAnalysis.VisualBasic.Symbols
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
@@ -28,11 +30,15 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Emit
             visitor.Visit(DirectCast(Me, Microsoft.Cci.IGenericTypeInstanceReference))
         End Sub
 
-        Private Function IGenericTypeInstanceReferenceGetGenericArguments(context As Microsoft.CodeAnalysis.Emit.Context) As IEnumerable(Of Microsoft.Cci.ITypeReference) Implements Microsoft.Cci.IGenericTypeInstanceReference.GetGenericArguments
+        Private Function IGenericTypeInstanceReferenceGetGenericArguments(context As Microsoft.CodeAnalysis.Emit.Context) As ImmutableArray(Of Microsoft.Cci.ITypeReference) Implements Microsoft.Cci.IGenericTypeInstanceReference.GetGenericArguments
             Dim moduleBeingBuilt As PEModuleBuilder = DirectCast(context.Module, PEModuleBuilder)
 
-            Return From type In m_UnderlyingNamedType.TypeArgumentsNoUseSiteDiagnostics
-                   Select moduleBeingBuilt.Translate(type, syntaxNodeOpt:=DirectCast(context.SyntaxNodeOpt, VisualBasicSyntaxNode), diagnostics:=context.Diagnostics)
+            Dim builder = ArrayBuilder(Of ITypeReference).GetInstance()
+            For Each t In m_UnderlyingNamedType.TypeArgumentsNoUseSiteDiagnostics
+                builder.Add(moduleBeingBuilt.Translate(t, syntaxNodeOpt:=DirectCast(context.SyntaxNodeOpt, VisualBasicSyntaxNode), diagnostics:=context.Diagnostics))
+            Next
+
+            Return builder.ToImmutableAndFree
         End Function
 
         Private ReadOnly Property IGenericTypeInstanceReferenceGenericType As Microsoft.Cci.INamedTypeReference Implements Microsoft.Cci.IGenericTypeInstanceReference.GenericType

Src/Compilers/VisualBasic/Source/Emit/SymbolTranslator.vb

@@ -433,7 +433,11 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Emit
         End Function
 
         Private Function TranslateAll(params As ImmutableArray(Of ParameterSymbol)) As ImmutableArray(Of Microsoft.Cci.IParameterTypeInformation)
-            Return params.SelectAsArray(Function(param) CreateParameterTypeInformationWrapper(param))
+            Dim builder = ArrayBuilder(Of Microsoft.Cci.IParameterTypeInformation).GetInstance()
+            For Each param In params
+                builder.Add(CreateParameterTypeInformationWrapper(param))
+            Next
+            Return builder.ToImmutableAndFree
         End Function
 
         Private Function CreateParameterTypeInformationWrapper(param As ParameterSymbol) As Cci.IParameterTypeInformation