Use switch expression

src/EditorFeatures/CSharp/AutomaticCompletion/AutomaticLineEnderCommandHandler.cs

@@ -151,18 +151,16 @@ protected override string GetEndingString(Document document, int position, Cance
         }
 
         private SyntaxNode ParseNode(SyntaxTree tree, SyntaxNode owningNode, string textToParse)
-        {
-            switch (owningNode)
+            => owningNode switch
             {
-                case BaseFieldDeclarationSyntax n: return SyntaxFactory.ParseCompilationUnit(WrapInType(textToParse), options: (CSharpParseOptions)tree.Options);
-                case BaseMethodDeclarationSyntax n: return SyntaxFactory.ParseCompilationUnit(WrapInType(textToParse), options: (CSharpParseOptions)tree.Options);
-                case BasePropertyDeclarationSyntax n: return SyntaxFactory.ParseCompilationUnit(WrapInType(textToParse), options: (CSharpParseOptions)tree.Options);
-                case StatementSyntax n: return SyntaxFactory.ParseStatement(textToParse, options: (CSharpParseOptions)tree.Options);
-                case UsingDirectiveSyntax n: return SyntaxFactory.ParseCompilationUnit(textToParse, options: (CSharpParseOptions)tree.Options);
-            }
-
-            return null;
-        }
+                BaseFieldDeclarationSyntax n => SyntaxFactory.ParseCompilationUnit(WrapInType(textToParse), options: (CSharpParseOptions)tree.Options),
+                BaseMethodDeclarationSyntax n => SyntaxFactory.ParseCompilationUnit(WrapInType(textToParse), options: (CSharpParseOptions)tree.Options),
+                BasePropertyDeclarationSyntax n => SyntaxFactory.ParseCompilationUnit(WrapInType(textToParse), options: (CSharpParseOptions)tree.Options),
+                StatementSyntax n => SyntaxFactory.ParseStatement(textToParse, options: (CSharpParseOptions)tree.Options),
+                UsingDirectiveSyntax n => SyntaxFactory.ParseCompilationUnit(textToParse, options: (CSharpParseOptions)tree.Options),
+
+                _ => (SyntaxNode)null,
+            };
 
         /// <summary>
         /// wrap field in type

src/EditorFeatures/CSharp/AutomaticCompletion/CSharpBraceCompletionSessionProvider.cs

@@ -68,25 +68,22 @@ protected override bool CheckCodeContext(Document document, int position, char o
         protected override IEditorBraceCompletionSession CreateEditorSession(Document document, int openingPosition, char openingBrace, CancellationToken cancellationToken)
         {
             var syntaxFactsService = document.GetLanguageService<ISyntaxFactsService>();
-            switch (openingBrace)
+            return openingBrace switch
             {
-                case BraceCompletionSessionProvider.CurlyBrace.OpenCharacter:
-                    return InterpolationCompletionSession.IsContext(document, openingPosition, cancellationToken)
-                        ? new InterpolationCompletionSession()
-                        : (IEditorBraceCompletionSession)new CurlyBraceCompletionSession(syntaxFactsService, _smartIndentationService, _undoManager);
+                BraceCompletionSessionProvider.CurlyBrace.OpenCharacter => InterpolationCompletionSession.IsContext(document, openingPosition, cancellationToken)
+                    ? new InterpolationCompletionSession()
+                    : (IEditorBraceCompletionSession)new CurlyBraceCompletionSession(syntaxFactsService, _smartIndentationService, _undoManager),
 
-                case BraceCompletionSessionProvider.DoubleQuote.OpenCharacter:
-                    return InterpolatedStringCompletionSession.IsContext(document, openingPosition, cancellationToken)
-                        ? new InterpolatedStringCompletionSession()
-                        : (IEditorBraceCompletionSession)new StringLiteralCompletionSession(syntaxFactsService);
+                BraceCompletionSessionProvider.DoubleQuote.OpenCharacter => InterpolatedStringCompletionSession.IsContext(document, openingPosition, cancellationToken)
+                    ? new InterpolatedStringCompletionSession()
+                    : (IEditorBraceCompletionSession)new StringLiteralCompletionSession(syntaxFactsService),
 
-                case BraceCompletionSessionProvider.Bracket.OpenCharacter: return new BracketCompletionSession(syntaxFactsService);
-                case BraceCompletionSessionProvider.Parenthesis.OpenCharacter: return new ParenthesisCompletionSession(syntaxFactsService);
-                case BraceCompletionSessionProvider.SingleQuote.OpenCharacter: return new CharLiteralCompletionSession(syntaxFactsService);
-                case BraceCompletionSessionProvider.LessAndGreaterThan.OpenCharacter: return new LessAndGreaterThanCompletionSession(syntaxFactsService);
-                default:
-                    throw ExceptionUtilities.UnexpectedValue(openingBrace);
-            }
+                BraceCompletionSessionProvider.Bracket.OpenCharacter => new BracketCompletionSession(syntaxFactsService),
+                BraceCompletionSessionProvider.Parenthesis.OpenCharacter => new ParenthesisCompletionSession(syntaxFactsService),
+                BraceCompletionSessionProvider.SingleQuote.OpenCharacter => new CharLiteralCompletionSession(syntaxFactsService),
+                BraceCompletionSessionProvider.LessAndGreaterThan.OpenCharacter => new LessAndGreaterThanCompletionSession(syntaxFactsService),
+                _ => throw ExceptionUtilities.UnexpectedValue(openingBrace),
+            };
         }
     }
 }

src/EditorFeatures/TestUtilities/Diagnostics/AbstractUserDiagnosticTest.cs

@@ -129,22 +129,14 @@ protected Document GetDocumentAndAnnotatedSpan(TestWorkspace workspace, out stri
                 return null;
             }
 
-            switch (annotation)
+            return annotation switch
             {
-                case "FixAllInDocument":
-                    return FixAllScope.Document;
-
-                case "FixAllInProject":
-                    return FixAllScope.Project;
-
-                case "FixAllInSolution":
-                    return FixAllScope.Solution;
-
-                case "FixAllInSelection":
-                    return FixAllScope.Custom;
-            }
-
-            throw new InvalidProgramException("Incorrect FixAll annotation in test");
+                "FixAllInDocument" => FixAllScope.Document,
+                "FixAllInProject" => FixAllScope.Project,
+                "FixAllInSolution" => FixAllScope.Solution,
+                "FixAllInSelection" => FixAllScope.Custom,
+                _ => throw new InvalidProgramException("Incorrect FixAll annotation in test"),
+            };
         }
 
         internal async Task<(ImmutableArray<Diagnostic>, ImmutableArray<CodeAction>, CodeAction actionToInvoke)> GetDiagnosticAndFixesAsync(

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

@@ -101,15 +101,12 @@ private SyntaxList<StatementSyntax> GetStatementsFromContainer(SyntaxNode node)
                     Contract.ThrowIfNull(node);
                     Contract.ThrowIfFalse(node.IsStatementContainerNode());
 
-                    switch (node)
+                    return node switch
                     {
-                        case BlockSyntax blockNode:
-                            return blockNode.Statements;
-                        case SwitchSectionSyntax switchSectionNode:
-                            return switchSectionNode.Statements;
-                    }
-
-                    return Contract.FailWithReturn<SyntaxList<StatementSyntax>>("unknown statements container!");
+                        BlockSyntax blockNode => blockNode.Statements,
+                        SwitchSectionSyntax switchSectionNode => switchSectionNode.Statements,
+                        _ => Contract.FailWithReturn<SyntaxList<StatementSyntax>>("unknown statements container!"),
+                    };
                 }
 
                 protected override SyntaxNode GetFirstStatementOrInitializerSelectedAtCallSite()

src/VisualStudio/Core/Def/Implementation/ProjectSystem/MiscellaneousFilesWorkspace.cs

@@ -402,16 +402,7 @@ protected override void Dispose(bool finalize)
         }
 
         public override bool CanApplyChange(ApplyChangesKind feature)
-        {
-            switch (feature)
-            {
-                case ApplyChangesKind.ChangeDocument:
-                    return true;
-
-                default:
-                    return false;
-            }
-        }
+            => feature == ApplyChangesKind.ChangeDocument;
 
         protected override void ApplyDocumentTextChanged(DocumentId documentId, SourceText newText)
         {

src/VisualStudio/Core/Impl/CodeModel/FileCodeModel_Events.cs

@@ -212,19 +212,13 @@ private object GetParentElementForCodeModelEvent(CodeModelEvent codeModelEvent)
         }
 
         private EnvDTE.CodeElement GetParameterElementForCodeModelEvent(CodeModelEvent codeModelEvent, object parentElement)
-        {
-            switch (parentElement)
+            => parentElement switch
             {
-                case EnvDTE.CodeDelegate parentDelegate:
-                    return GetParameterElementForCodeModelEvent(codeModelEvent, parentDelegate.Parameters, parentElement);
-                case EnvDTE.CodeFunction parentFunction:
-                    return GetParameterElementForCodeModelEvent(codeModelEvent, parentFunction.Parameters, parentElement);
-                case EnvDTE80.CodeProperty2 parentProperty:
-                    return GetParameterElementForCodeModelEvent(codeModelEvent, parentProperty.Parameters, parentElement);
-            }
-
-            return null;
-        }
+                EnvDTE.CodeDelegate parentDelegate => GetParameterElementForCodeModelEvent(codeModelEvent, parentDelegate.Parameters, parentElement),
+                EnvDTE.CodeFunction parentFunction => GetParameterElementForCodeModelEvent(codeModelEvent, parentFunction.Parameters, parentElement),
+                EnvDTE80.CodeProperty2 parentProperty => GetParameterElementForCodeModelEvent(codeModelEvent, parentProperty.Parameters, parentElement),
+                _ => null,
+            };
 
         private EnvDTE.CodeElement GetParameterElementForCodeModelEvent(CodeModelEvent codeModelEvent, EnvDTE.CodeElements parentParameters, object parentElement)
         {

src/VisualStudio/Core/SolutionExplorerShim/DiagnosticItem/BaseDiagnosticItem.BrowseObject.cs

@@ -127,21 +127,14 @@ public BaseDiagnosticItem DiagnosticItem
             }
 
             private string MapDiagnosticSeverityToText(DiagnosticSeverity severity)
-            {
-                switch (severity)
+                => severity switch
                 {
-                    case DiagnosticSeverity.Hidden:
-                        return SolutionExplorerShim.Hidden;
-                    case DiagnosticSeverity.Info:
-                        return SolutionExplorerShim.Info;
-                    case DiagnosticSeverity.Warning:
-                        return SolutionExplorerShim.Warning;
-                    case DiagnosticSeverity.Error:
-                        return SolutionExplorerShim.Error_;
-                    default:
-                        throw ExceptionUtilities.UnexpectedValue(severity);
-                }
-            }
+                    DiagnosticSeverity.Hidden => SolutionExplorerShim.Hidden,
+                    DiagnosticSeverity.Info => SolutionExplorerShim.Info,
+                    DiagnosticSeverity.Warning => SolutionExplorerShim.Warning,
+                    DiagnosticSeverity.Error => SolutionExplorerShim.Error_,
+                    _ => throw ExceptionUtilities.UnexpectedValue(severity),
+                };
 
             private string MapReportDiagnosticToText(ReportDiagnostic report)
             {

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

@@ -2765,19 +2765,13 @@ public override SyntaxNode InsertAccessors(SyntaxNode declaration, int index, IE
         }
 
         private static AccessorListSyntax GetAccessorList(SyntaxNode declaration)
-        {
-            switch (declaration.Kind())
+            => declaration.Kind() switch
             {
-                case SyntaxKind.PropertyDeclaration:
-                    return ((PropertyDeclarationSyntax)declaration).AccessorList;
-                case SyntaxKind.IndexerDeclaration:
-                    return ((IndexerDeclarationSyntax)declaration).AccessorList;
-                case SyntaxKind.EventDeclaration:
-                    return ((EventDeclarationSyntax)declaration).AccessorList;
-                default:
-                    return null;
-            }
-        }
+                SyntaxKind.PropertyDeclaration => ((PropertyDeclarationSyntax)declaration).AccessorList,
+                SyntaxKind.IndexerDeclaration => ((IndexerDeclarationSyntax)declaration).AccessorList,
+                SyntaxKind.EventDeclaration => ((EventDeclarationSyntax)declaration).AccessorList,
+                _ => null,
+            };
 
         private static bool CanHaveAccessors(SyntaxNode declaration)
         {