simplify some code

src/OmniSharp.Host/Endpoint/EndpointHandler.cs

@@ -106,9 +106,8 @@ public override Task<object> Handle(RequestPacket packet)
         public async Task<object> Process(RequestPacket packet, LanguageModel model, JToken requestObject)
         {
             var request = requestObject.ToObject<TRequest>();
-            if (request is Request && _updateBufferHandler.Value != null)
+            if (request is Request realRequest && _updateBufferHandler.Value != null)
             {
-                var realRequest = request as Request;
                 if (!string.IsNullOrWhiteSpace(realRequest.FileName) && (realRequest.Buffer != null || realRequest.Changes != null))
                 {
                     await _updateBufferHandler.Value.Process(packet, model, requestObject);

src/OmniSharp.Roslyn.CSharp/Services/Intellisense/IntellisenseService.cs

@@ -130,16 +130,12 @@ public async Task<IEnumerable<AutoCompleteResponse>> Handle(AutoCompleteRequest
 
         private IEnumerable<AutoCompleteResponse> MakeSnippetedResponses(AutoCompleteRequest request, ISymbol symbol, string completionText, bool preselect, bool isSuggestionMode)
         {
-            switch (symbol)
+            return symbol switch
             {
-                case IMethodSymbol methodSymbol:
-                    return MakeSnippetedResponses(request, methodSymbol, completionText, preselect, isSuggestionMode);
-                case INamedTypeSymbol typeSymbol:
-                    return MakeSnippetedResponses(request, typeSymbol, completionText, preselect, isSuggestionMode);
-
-                default:
-                    return new[] { MakeAutoCompleteResponse(request, symbol, completionText, preselect, isSuggestionMode) };
-            }
+                IMethodSymbol methodSymbol => MakeSnippetedResponses(request, methodSymbol, completionText, preselect, isSuggestionMode),
+                INamedTypeSymbol typeSymbol => MakeSnippetedResponses(request, typeSymbol, completionText, preselect, isSuggestionMode),
+                _ => new[] { MakeAutoCompleteResponse(request, symbol, completionText, preselect, isSuggestionMode) },
+            };
         }
 
         private IEnumerable<AutoCompleteResponse> MakeSnippetedResponses(AutoCompleteRequest request, IMethodSymbol methodSymbol, string completionText, bool preselect, bool isSuggestionMode)

src/OmniSharp.Roslyn.CSharp/Workers/Intellisense/ReturnTypeFormatter.cs

@@ -12,46 +12,17 @@ public static string GetReturnType(ISymbol symbol)
 
         private static ITypeSymbol GetReturnTypeSymbol(ISymbol symbol)
         {
-            var methodSymbol = symbol as IMethodSymbol;
-            if (methodSymbol != null)
+            return symbol switch
             {
-                if (methodSymbol.MethodKind != MethodKind.Constructor)
-                {
-                    return methodSymbol.ReturnType;
-                }
-            }
-
-            var propertySymbol = symbol as IPropertySymbol;
-            if (propertySymbol != null)
-            {
-                return propertySymbol.Type;
-            }
-
-            var localSymbol = symbol as ILocalSymbol;
-            if (localSymbol != null)
-            {
-                return localSymbol.Type;
-            }
-
-            var parameterSymbol = symbol as IParameterSymbol;
-            if (parameterSymbol != null)
-            {
-                return parameterSymbol.Type;
-            }
-
-            var fieldSymbol = symbol as IFieldSymbol;
-            if (fieldSymbol != null)
-            {
-                return fieldSymbol.Type;
-            }
-
-            var eventSymbol = symbol as IEventSymbol;
-            if (eventSymbol != null)
-            {
-                return eventSymbol.Type;
-            }
-
-            return null;
+                IMethodSymbol methodSymbol when methodSymbol.MethodKind != MethodKind.Constructor
+                        => methodSymbol.ReturnType,
+                IPropertySymbol propertySymbol => propertySymbol.Type,
+                ILocalSymbol localSymbol => localSymbol.Type,
+                IParameterSymbol parameterSymbol => parameterSymbol.Type,
+                IFieldSymbol fieldSymbol => fieldSymbol.Type,
+                IEventSymbol eventSymbol => eventSymbol.Type,
+                _ => null
+            };
         }
     }
 }

src/OmniSharp.Roslyn.CSharp/Workers/Intellisense/SnippetGenerator.cs

@@ -27,12 +27,10 @@ public string Generate(ISymbol symbol)
                 // only the containing type contains the type parameters
                 var parts = symbol.ContainingType.ToDisplayParts(_format);
                 RenderDisplayParts(symbol, parts);
-                parts = symbol.ToDisplayParts(_format);
                 RenderParameters(symbol as IMethodSymbol);
             }
             else
             {
-                var symbolKind = symbol.Kind;
                 if (symbol.Kind == SymbolKind.Method)
                 {
                     RenderMethodSymbol(symbol as IMethodSymbol);
@@ -154,8 +152,7 @@ private IEnumerable<ISymbol> ParameterTypes(IMethodSymbol methodSymbol)
 
         private IEnumerable<ISymbol> ExplodeTypes(ISymbol symbol)
         {
-            var typeSymbol = symbol as INamedTypeSymbol;
-            if (typeSymbol != null)
+            if (symbol is INamedTypeSymbol typeSymbol)
             {
                 var typeParams = typeSymbol.TypeArguments;
 

tests/TestUtility/DotNetCliVersion.cs

@@ -12,12 +12,12 @@ public static class DotNetCliVersionExtensions
     {
         public static string GetFolderName(this DotNetCliVersion dotNetCliVersion)
         {
-            switch (dotNetCliVersion)
+            return dotNetCliVersion switch
             {
-                case DotNetCliVersion.Current: return ".dotnet";
-                case DotNetCliVersion.Future: throw new InvalidOperationException("Test infrastructure does not support a future .NET Core SDK yet.");
-                default: throw new ArgumentException($"Unknown {nameof(dotNetCliVersion)}: {dotNetCliVersion}", nameof(dotNetCliVersion));
-            }
+                DotNetCliVersion.Current => ".dotnet",
+                DotNetCliVersion.Future => throw new InvalidOperationException("Test infrastructure does not support a future .NET Core SDK yet."),
+                _ => throw new ArgumentException($"Unknown {nameof(dotNetCliVersion)}: {dotNetCliVersion}", nameof(dotNetCliVersion)),
+            };
         }
     }
 }