Use pattern matching

src/EditorFeatures/Core.Wpf/Interactive/InteractiveDocumentNavigationService.cs

@@ -32,15 +32,17 @@ public bool CanNavigateToPosition(Workspace workspace, DocumentId documentId, in
 
         public bool TryNavigateToSpan(Workspace workspace, DocumentId documentId, TextSpan textSpan, OptionSet options)
         {
-            var interactiveWorkspace = workspace as InteractiveWorkspace;
-            if (interactiveWorkspace == null)
+            using (var interactiveWorkspace = workspace as InteractiveWorkspace)
             {
-                Debug.Fail("InteractiveDocumentNavigationService called with incorrect workspace!");
-                return false;
-            }
+                if (interactiveWorkspace == null)
+                {
+                    Debug.Fail("InteractiveDocumentNavigationService called with incorrect workspace!");
+                    return false;
+                }
 
-            var textView = interactiveWorkspace.Window.TextView;
-            var document = interactiveWorkspace.CurrentSolution.GetDocument(documentId);
+                var textView = interactiveWorkspace.Window.TextView;
+                var document = interactiveWorkspace.CurrentSolution.GetDocument(documentId);
+            }
 
             var textSnapshot = document.GetTextSynchronously(CancellationToken.None).FindCorrespondingEditorTextSnapshot();
             if (textSnapshot == null)

src/EditorFeatures/Core/Extensibility/BraceMatching/AbstractDirectiveTriviaBraceMatcher.cs

@@ -28,8 +28,7 @@ internal abstract class AbstractDirectiveTriviaBraceMatcher<TDirectiveTriviaSynt
             var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
             var token = root.FindToken(position, findInsideTrivia: true);
 
-            var directive = token.Parent as TDirectiveTriviaSyntax;
-            if (directive == null)
+            if (!(token.Parent is TDirectiveTriviaSyntax directive))
             {
                 return null;
             }

src/Features/CSharp/Portable/CodeFixes/Iterator/CSharpAddYieldCodeFixProvider.cs

@@ -91,8 +91,7 @@ private bool TryGetMethodReturnType(SyntaxNode node, SemanticModel model, Cancel
         {
             methodReturnType = null;
             var symbol = model.GetEnclosingSymbol(node.Span.Start, cancellationToken);
-            var method = symbol as IMethodSymbol;
-            if (method == null || method.ReturnsVoid)
+            if (!(symbol is IMethodSymbol method) || method.ReturnsVoid)
             {
                 return false;
             }

src/Features/CSharp/Portable/ExtractMethod/CSharpMethodExtractor.CSharpCodeGenerator.cs

@@ -313,8 +313,7 @@ private OperationStatus CheckActiveStatements(IEnumerable<StatementSyntax> state
 
                 foreach (var statement in statements)
                 {
-                    var declarationStatement = statement as LocalDeclarationStatementSyntax;
-                    if (declarationStatement == null)
+                    if (!(statement is LocalDeclarationStatementSyntax declarationStatement))
                     {
                         // if given statement is not decl statement.
                         yield return statement;

src/Features/Core/Portable/ConvertAutoPropertyToFullProperty/AbstractConvertAutoPropertyToFullPropertyCodeRefactoringProvider.cs

@@ -41,8 +41,7 @@ public override async Task ComputeRefactoringsAsync(CodeRefactoringContext conte
 
             var semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
 
-            var propertySymbol = semanticModel.GetDeclaredSymbol(property) as IPropertySymbol;
-            if (propertySymbol == null)
+            if (!(semanticModel.GetDeclaredSymbol(property) is IPropertySymbol propertySymbol))
             {
                 return;
             }

src/Features/Core/Portable/Diagnostics/LiveDiagnosticUpdateArgsId.cs

@@ -26,8 +26,7 @@ public LiveDiagnosticUpdateArgsId(DiagnosticAnalyzer analyzer, object key, int k
 
         public override bool Equals(object obj)
         {
-            var other = obj as LiveDiagnosticUpdateArgsId;
-            if (other == null)
+            if (!(obj is LiveDiagnosticUpdateArgsId other))
             {
                 return false;
             }

src/VisualStudio/CSharp/Impl/CodeModel/CSharpCodeModelService.CodeModelEventCollector.cs

@@ -182,9 +182,8 @@ private bool CompareExpressions(ExpressionSyntax oldExpression, ExpressionSyntax
                         && CompareExpressions(oldBinaryExpression.Right, newBinaryExpression.Right);
                 }
 
-                if (oldExpression is AssignmentExpressionSyntax)
+                if (oldExpression is AssignmentExpressionSyntax oldAssignmentExpression)
                 {
-                    var oldAssignmentExpression = (AssignmentExpressionSyntax)oldExpression;
                     var newAssignmentExpression = (AssignmentExpressionSyntax)newExpression;
 
                     return CompareExpressions(oldAssignmentExpression.Left, newAssignmentExpression.Left)

src/VisualStudio/CSharp/Impl/CodeModel/CSharpCodeModelService.cs

@@ -1163,9 +1163,7 @@ private EnvDTE.vsCMAccess GetDefaultAccessibility(SyntaxNode node)
 
         public override SyntaxNode SetAccess(SyntaxNode node, EnvDTE.vsCMAccess newAccess)
         {
-            var member = node as MemberDeclarationSyntax;
-
-            if (member == null)
+            if (!(node is MemberDeclarationSyntax member))
             {
                 throw Exceptions.ThrowEFail();
             }

src/VisualStudio/CSharp/Impl/Debugging/CSharpProximityExpressionsService.Worker.cs

@@ -98,8 +98,7 @@ private BlockSyntax GetImmediatelyContainingBlock()
 
             private bool IsFirstBlockStatement()
             {
-                var parentBlockOpt = _parentStatement.Parent as BlockSyntax;
-                return parentBlockOpt != null && parentBlockOpt.Statements.FirstOrDefault() == _parentStatement;
+                return _parentStatement.Parent is BlockSyntax parentBlockOpt && parentBlockOpt.Statements.FirstOrDefault() == _parentStatement;
             }
 
             private void AddCurrentDeclaration()

src/VisualStudio/Core/Def/Implementation/ProjectSystem/Legacy/AbstractLegacyProject.cs

@@ -207,8 +207,7 @@ protected void RemoveFile(string filename)
 
         protected void RefreshBinOutputPath()
         {
-            var storage = Hierarchy as IVsBuildPropertyStorage;
-            if (storage == null)
+            if (!(Hierarchy is IVsBuildPropertyStorage storage))
             {
                 return;
             }

src/VisualStudio/Core/Impl/Options/Style/NamingPreferences/NamingStyleOptionPageControl.xaml.cs

@@ -121,8 +121,7 @@ private void SetFocusToSelectedRow()
         {
             if (CodeStyleMembers.SelectedIndex >= 0)
             {
-                var row = CodeStyleMembers.ItemContainerGenerator.ContainerFromIndex(CodeStyleMembers.SelectedIndex) as DataGridRow;
-                if (row == null)
+                if (!(CodeStyleMembers.ItemContainerGenerator.ContainerFromIndex(CodeStyleMembers.SelectedIndex) is DataGridRow row))
                 {
                     CodeStyleMembers.ScrollIntoView(CodeStyleMembers.SelectedItem);
                     row = CodeStyleMembers.ItemContainerGenerator.ContainerFromIndex(CodeStyleMembers.SelectedIndex) as DataGridRow;

src/Workspaces/CSharp/Portable/CodeGeneration/CSharpSyntaxGenerator.cs

@@ -2201,8 +2201,7 @@ public override SyntaxNode GetType(SyntaxNode declaration)
 
         private static TypeSyntax NotVoid(TypeSyntax type)
         {
-            var pd = type as PredefinedTypeSyntax;
-            return pd != null && pd.Keyword.IsKind(SyntaxKind.VoidKeyword) ? null : type;
+            return type is PredefinedTypeSyntax pd && pd.Keyword.IsKind(SyntaxKind.VoidKeyword) ? null : type;
         }
 
         public override SyntaxNode WithType(SyntaxNode declaration, SyntaxNode type)
@@ -2383,8 +2382,7 @@ public override IReadOnlyList<SyntaxNode> GetSwitchSections(SyntaxNode switchSta
 
         public override SyntaxNode InsertSwitchSections(SyntaxNode switchStatement, int index, IEnumerable<SyntaxNode> switchSections)
         {
-            var statement = switchStatement as SwitchStatementSyntax;
-            if (statement == null)
+            if (!(switchStatement is SwitchStatementSyntax statement))
             {
                 return switchStatement;
             }

src/Workspaces/CSharp/Portable/Indentation/CSharpIndentationService.Indenter.cs

@@ -344,8 +344,7 @@ private IndentationResult GetIndentationForQueryExpression(SyntaxToken token)
                 }
 
                 // find query body that has a token that is a first token on the line
-                var queryBody = queryExpressionClause.Parent as QueryBodySyntax;
-                if (queryBody == null)
+                if (!(queryExpressionClause.Parent is QueryBodySyntax queryBody))
                 {
                     return GetIndentationOfToken(firstToken);
                 }

src/Workspaces/CSharp/Portable/Utilities/SpeculationAnalyzer.cs

@@ -114,9 +114,8 @@ public static SemanticModel CreateSpeculativeSemanticModelForNode(SyntaxNode nod
                 semanticModel = semanticModel.ParentModel;
             }
 
-            var statementNode = nodeToSpeculate as StatementSyntax;
             SemanticModel speculativeModel;
-            if (statementNode != null)
+            if (nodeToSpeculate is StatementSyntax statementNode)
             {
                 semanticModel.TryGetSpeculativeSemanticModel(position, statementNode, out speculativeModel);
                 return speculativeModel;