support GFU inside nameof for C# and VB

***NO_CI***
 (changeset 1371266)

Src/Workspaces/CSharp/Portable/Extensions/ContextQuery/SyntaxTreeExtensions.cs

@@ -2075,7 +2075,7 @@ public static bool IsLabelContext(this SyntaxTree syntaxTree, int position, Canc
             return false;
         }
 
-        public static bool IsNameOfContext(this SyntaxTree syntaxTree, int position, SemanticModel semanticModelOpt, CancellationToken cancellationToken)
+        public static bool IsNameOfContext(this SyntaxTree syntaxTree, int position, SemanticModel semanticModelOpt = null, CancellationToken cancellationToken = default(CancellationToken))
         {
             var token = syntaxTree.FindTokenOnLeftOfPosition(position, cancellationToken);
             token = token.GetPreviousTokenIfTouchingWord(position);

Src/Workspaces/CSharp/Portable/Extensions/ISemanticModelExtensions.cs

@@ -60,42 +60,42 @@ private static void DecomposeName(ExpressionSyntax expression, out ExpressionSyn
         {
             switch (expression.CSharpKind())
             {
-                case SyntaxKind.SimpleMemberAccessExpression:
-                case SyntaxKind.PointerMemberAccessExpression:
-                    var max = (MemberAccessExpressionSyntax)expression;
-                    qualifier = max.Expression;
-                    name = max.Name.Identifier.ValueText;
-                    arity = max.Name.Arity;
-                    break;
-                case SyntaxKind.QualifiedName:
-                    var qn = (QualifiedNameSyntax)expression;
-                    qualifier = qn.Left;
-                    name = qn.Right.Identifier.ValueText;
-                    arity = qn.Arity;
-                    break;
-                case SyntaxKind.AliasQualifiedName:
-                    var aq = (AliasQualifiedNameSyntax)expression;
-                    qualifier = aq.Alias;
-                    name = aq.Name.Identifier.ValueText;
-                    arity = aq.Name.Arity;
-                    break;
-                case SyntaxKind.GenericName:
-                    var gx = (GenericNameSyntax)expression;
-                    qualifier = null;
-                    name = gx.Identifier.ValueText;
-                    arity = gx.Arity;
-                    break;
-                case SyntaxKind.IdentifierName:
-                    var nx = (IdentifierNameSyntax)expression;
-                    qualifier = null;
-                    name = nx.Identifier.ValueText;
-                    arity = 0;
-                    break;
-                default:
-                    qualifier = null;
-                    name = null;
-                    arity = 0;
-                    break;
+            case SyntaxKind.SimpleMemberAccessExpression:
+            case SyntaxKind.PointerMemberAccessExpression:
+                var max = (MemberAccessExpressionSyntax)expression;
+                qualifier = max.Expression;
+                name = max.Name.Identifier.ValueText;
+                arity = max.Name.Arity;
+                break;
+            case SyntaxKind.QualifiedName:
+                var qn = (QualifiedNameSyntax)expression;
+                qualifier = qn.Left;
+                name = qn.Right.Identifier.ValueText;
+                arity = qn.Arity;
+                break;
+            case SyntaxKind.AliasQualifiedName:
+                var aq = (AliasQualifiedNameSyntax)expression;
+                qualifier = aq.Alias;
+                name = aq.Name.Identifier.ValueText;
+                arity = aq.Name.Arity;
+                break;
+            case SyntaxKind.GenericName:
+                var gx = (GenericNameSyntax)expression;
+                qualifier = null;
+                name = gx.Identifier.ValueText;
+                arity = gx.Arity;
+                break;
+            case SyntaxKind.IdentifierName:
+                var nx = (IdentifierNameSyntax)expression;
+                qualifier = null;
+                name = nx.Identifier.ValueText;
+                arity = 0;
+                break;
+            default:
+                qualifier = null;
+                name = null;
+                arity = 0;
+                break;
             }
         }
 
@@ -163,9 +163,9 @@ private static bool CanBindToken(SyntaxToken token)
             // Add more token kinds if necessary;
             switch (token.CSharpKind())
             {
-                case SyntaxKind.CommaToken:
-                case SyntaxKind.DelegateKeyword:
-                    return false;
+            case SyntaxKind.CommaToken:
+            case SyntaxKind.DelegateKeyword:
+                return false;
             }
 
             return true;
@@ -315,7 +315,10 @@ public static ISet<INamespaceSymbol> GetUsingNamespacesInScope(this SemanticMode
             TypeSyntax type,
             CancellationToken cancellationToken)
         {
-            type = GetOutermostType(type);
+            if (type != null)
+            {
+                type = GetOutermostType(type);
+            }
 
             // Interesting cases based on 3.5.4 Accessibility constraints in the language spec.
             // If any of the below hold, then we will override the default accessibility if the

Src/Workspaces/CSharp/Portable/LanguageServices/CSharpSemanticFactsService.cs

@@ -262,5 +262,10 @@ public bool IsAssignableTo(ITypeSymbol fromSymbol, ITypeSymbol toSymbol, Compila
                 toSymbol != null &&
                 ((CSharpCompilation)compilation).ClassifyConversion(fromSymbol, toSymbol).IsImplicit;
         }
+
+        public bool IsNameOfContext(SemanticModel semanticModel, int position, CancellationToken cancellationToken)
+        {
+            return semanticModel.SyntaxTree.IsNameOfContext(position, semanticModel, cancellationToken);
+        }
     }
 }
\ No newline at end of file

Src/Workspaces/Core/Portable/LanguageServices/SemanticsFactsService/ISemanticFactsService.cs

@@ -48,6 +48,7 @@ internal interface ISemanticFactsService : ILanguageService
         bool IsGlobalStatementContext(SemanticModel semanticModel, int position, CancellationToken cancellationToken);
         bool IsLabelContext(SemanticModel semanticModel, int position, CancellationToken cancellationToken);
         bool IsAttributeNameContext(SemanticModel semanticModel, int position, CancellationToken cancellationToken);
+        bool IsNameOfContext(SemanticModel semanticModel, int position, CancellationToken cancellationToken);
 
         /// <summary>
         /// True if a write is performed to the given expression.  Note: reads may also be performed

Src/Workspaces/VisualBasic/Portable/Extensions/ContextQuery/SyntaxTreeExtensions.vb

@@ -447,6 +447,26 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Extensions.ContextQuery
             Return token.IsChildToken(Of SimpleAsClauseSyntax)(Function(asClause) asClause.AsKeyword)
         End Function
 
+        <Extension()>
+        Public Function IsNameOfContext(syntaxTree As SyntaxTree, position As Integer, token As SyntaxToken, Optional cancellationToken As CancellationToken = Nothing) As Boolean
+            ' first do quick exit check
+            If syntaxTree.IsInPreprocessorDirectiveContext(position, cancellationToken) OrElse
+               syntaxTree.IsInInactiveRegion(position, cancellationToken) OrElse
+               syntaxTree.IsEntirelyWithinComment(position, cancellationToken) OrElse
+               syntaxTree.IsEntirelyWithinStringOrCharLiteral(position, cancellationToken) Then
+
+                Return False
+            End If
+
+            Contract.Requires(token = syntaxTree.GetTargetToken(position, cancellationToken))
+
+            If token.IsChildToken(Of NameOfExpressionSyntax)(Function(importAliasClause) importAliasClause.OpenParenToken) Then
+                Return True
+            End If
+
+            Return False
+        End Function
+
         <Extension()>
         Friend Function IsSingleLineStatementContext(syntaxTree As SyntaxTree, position As Integer, cancellationToken As CancellationToken) As Boolean
             Dim targetToken = syntaxTree.GetTargetToken(position, cancellationToken)

Src/Workspaces/VisualBasic/Portable/LanguageServices/VisualBasicSemanticFactsService.vb

@@ -245,5 +245,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Public Function IsAssignableTo(fromSymbol As ITypeSymbol, toSymbol As ITypeSymbol, compilation As Compilation) As Boolean Implements ISemanticFactsService.IsAssignableTo
             Return fromSymbol IsNot Nothing AndAlso toSymbol IsNot Nothing AndAlso DirectCast(compilation, VisualBasicCompilation).ClassifyConversion(fromSymbol, toSymbol).IsWidening
         End Function
+
+        Public Function IsNameOfContext(semanticModel As SemanticModel, position As Integer, cancellationToken As CancellationToken) As Boolean Implements ISemanticFactsService.IsNameOfContext
+            Dim token = semanticModel.SyntaxTree.GetTargetToken(position, cancellationToken)
+            Return semanticModel.SyntaxTree.IsNameOfContext(position, token, cancellationToken)
+        End Function
     End Class
 End Namespace
\ No newline at end of file